Green tea is second only to water as the most consumed beverage in the world. It has been used medicinally for centuries in India and China. Green tea is prepared by picking, lightly steaming and allowing the leaves to dry whereas black tea is fermented before drying. Fermentation can destroy some of the active components of black tea. The active constituents in green tea are powerful antioxidants called polyphenols (catechins) and flavonols. Tannins in tea are large polyphenol molecules and form the bulk of the active compounds in green tea, while catechins make up nearly 90% of the tannins. Several catechins are present in significant quantities and account for the bulk of research: epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (ECG) and epigallocatechin gallate EGCG. EGCG accounts for 10-50% of the total catechin content and appears to be the most powerful of the catechins; its antioxidant activity about 25-100 times more potent than vitamins C and E. One cup of green tea may provide 10-40mg of polyphenols and has antioxidant activity greater than a serving of broccoli, spinach, carrots or strawberries. Research shows that green tea may have be anti-atherogenic by reducing cholesterol & triglycerides; reduce blood clotting; enhance immune function; enhance weight loss; and be anti-cancenogenic.

Theoretically, the high antioxidant activity of green tea makes it beneficial by protecting the body from oxidative damage due to free radicals. Diseases that are association with free radical damage include cancer, heart disease, suppressed immune function, and accelerated aging.

In the laboratory, green tea is an effective antioxidant. It can protect against experimentally induced DNA damage; and slow or halt the initiation and progression of cancerous tumor growth. There is also evidence from some studies that green tea provides significant immunoprotective qualities, particularly in the case of cancer patients undergoing radiation or chemotherapy. White blood cell count appears to be maintained more effectively in cancer patients consuming green tea compared to non-supplemented patients

There may also be an anti-obesity action of green tea. In one study, mice receiving green tea in their diets had a significant suppression of food intake, body weight gain and fat tissue accumulation. Also, levels of cholesterol and triglycerides were lower in mice receiving the green tea diet and leptin levels in serum showed a decrease with green tea treatments – indicating that green tea may have a direct effect reducing body weight.

Dosage: Typical dosage recommendations are for 125-500mg/day – preferably of an extract standardized to at least 60% polyphenols and/or EGCG as a marker compound (this should be equivalent to 4-10 cups of brewed green tea).

Side Effects: Green tea consumption of as much as 20 cups per day has not been associated with any significant side effects. In high doses, teas that contain caffeine may lead to restlessness, insomnia, and tachycardia. Decaffeinated versions of green tea and green tea extracts are available – but the amounts of phenolic/catechin compounds can vary between extracts.

(Source: www.supplementwatch.com)

Research Overview

Green Tea:
1. Prevents tumor growth and metastasis
2. May be used to control H pylori gastric disease
3. May be an effective therapy in treating human papilloma virus (HPV) cervical lesions
4. Protects normal cells from the radiation of cancer cells
5. Is a powerful antioxidant
6. May be used as an anti-inflammatory for the skin
7. Reduces risk of breast cancer
8. Reduces risk of lung cancer
9. Reduces risk of cancer in alcohol drinkers
10. Reduces risk of cancer in cigarette smokers
11. Reduces the risk of cancer from proximity to PCP pollutants
12. Used in treatment for cervical cancer
13. Protects prostate from tumor development
14. Protects bladder from tumor development
15. Protects from gastric atrophy during fasting
16. Diminishes lipid peroxidation in the brain
17. May be used to treat skin tumors
18. Control growth of myelogenic leukemia cells
19. May prevent atherosclerosis
20. Is a free radical scavenger
21. May prevent Parkinson’s disease
22. May be used to treat periodontal disease
23. Halts development of breast cancer tumors
24. May help prevent cataracts
25. May be effective in treating neurodegenerative diseases
26. Is beneficial in the treatment of diabetes
27. May prevent liver damage from alcohol
28. May prevent cancer of the mouth
29. Reduces inflammation in arthritis
30. Lowers total cholesterol levels
31. Prevents ishemic cardiac damage
32. May prevent Alzheimer's disease
33. May be used to treat baldness
34. May control obesity
35. Reduces risk of colon cancer

Green Tea Abstracts (292)

1. J Agric Food Chem. 2003 Oct 22;51(22):6627-34.

A Combination of Tea (Camellia senensis) Catechins Is Required for Optimal Inhibition of Induced CYP1A Expression by Green Tea Extract.

Williams SN, Pickwell GV, Quattrochi LC.

Department of Medicine, Section of Medical Toxicology, University of Colorado Health Sciences Center, Denver, Colorado 80262.

It was previously demonstrated that the commercial green tea extract Polyphenon 100 (P100), and to a lesser extent (-)-epigallocatechin-3-gallate (EGCG), partially antagonizes 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced transcription of human CYP1A1 (Williams, S. N.; Shih, H.; Guenette, D. K.; Brackney, W.; Denison, M. S.; Pickwell, G. V.; Quattrochi, L. C. Chem.-Biol. Interact. 2000, 128, 211-229). Here, P100 is compared to a reconstituted mixture of the four major tea catechins (referred to as P100R) to determine whether inhibition was due to additional polyphenols in the extract or from synergistic interactions among the tea catechins. It was found that cotreatment of cells with TCDD and either P100 or P100R inhibited TCDD-induced CYP1A promoter-driven luciferase reporter activity (HepG2 cells) and CYP1A expression (HepG2 and primary human hepatocytes), similarly. These results indicate that modulation of human CYP1A expression by P100 can be attributed entirely to the combination of the four tea catechins. These findings may be important in the evaluation of future chemoprevention strategies using green tea and single catechin agents.

2. Biochem Biophys Res Commun. 2003 Oct 24;310(3):715-719.

Suppression of Helicobacter pylori-induced gastritis by green tea extract in Mongolian gerbils.

Matsubara S, Shibata H, Ishikawa F, Yokokura T, Takahashi M, Sugimura T, Wakabayashi K.

Cancer Prevention Basic Research Project, National Cancer Center Research Institute, 1-1, Tsukiji 5-chome, Chuo-ku, 104-0045, Tokyo, Japan

Since urease of Helicobacter pylori is essential for its colonization, we focused attention on foodstuffs which inhibit the activity of this enzyme. Among plant-derived 77 foodstuff samples tested, some tea and rosemary extracts were found to clearly inhibit H. pylori urease in vitro. In particular, green tea extract (GTE) showed the strongest inhibition of H. pylori urease, with an IC(50) value of 13microg/ml. Active principles were identified to be catechins, the hydroxyl group of 5(')-position appearing important for urease inhibition. Furthermore, when H. pylori-inoculated Mongolian gerbils were given GTE in drinking water at the concentrations of 500, 1000, and 2000ppm for 6 weeks, gastritis and the prevalence of H. pylori-infected animals were suppressed in a dose-dependent manner. Since the acquisition by H. pylori of resistance to antibiotics has become a serious problem, tea and tea catechins may be very safe resources to control H. pylori-associated gastroduodenal diseases.

3. Cell Mol Life Sci. 2003 Aug;60(8):1760-3.

Green tea epigallocatechin-3-gallate is an inhibitor of mammalian histidine decarboxylase.

Rodriguez-Caso C, Rodriguez-Agudo D, Sanchez-Jimenez F, Medina MA.

Department of Molecular Biology and Biochemistry, Faculty of Sciences, University of Malaga, Malaga, Spain.

(-)-epigallocatechin-3-gallate, an antiproliferative and antiangiogenic component of green tea, has been reported to inhibit dopa decarboxylase. In this report,we show that this compound also inhibits histidine decarboxylase, the enzymic activity responsible for histamine biosynthesis. This inhibition was proved by a double approach, activity measurements and UV-Vis spectra of enzyme-bound pyridoxal-5'-phosphate. At 0.1 mM (-)-epi-gallocatechin-3-gallate, histidine decarboxylase activity was inhibited by more than 60% and the typical spectrum of the internal aldimine form shifted to a stable major maximum at 345 nm, suggesting that the compound causes a stable change in the structure of the holoenzyme.Since histamine release is one of the primary events in many inflammatory responses, a new potential application of (-)-epigallocatechin-3-gallate in prevention or treatment of inflammatory processes is suggested by these data.

4. Eur J Cancer Prev. 2003 Oct;12(5):391-5.

Effects of green tea on carcinogen-induced hepatic CYP1As in C57BL/6 mice.

Yang M, Yoshikawa M, Arashidani K, Kawamoto T.

Department of Preventive Medicine/Cancer Research Institute, Seoul National University College of Medicine, 28 Yongon-Dong Chongno-Gu, 110-799 Seoul, Korea.

SUMMARY: Green tea (GT) drinking showed chemopreventive effects on various cancers. In addition, inhibition of CYP1A activity by green tea components-polyphenols-has been suggested as a chemoprevention against carcinogens that were bioactivated by CYP1As. Therefore, any changes in hepatic CYP1As may be considered as a biomarker for GT chemoprevention and clarify whether whole GT is chemopreventive for the population who are exposed to CYP1A specifically-bioactivated carcinogens. In this study, we investigated the changes in CYP1A levels by pre- and concurrent GT drinking against a CYP1A-inducing carcinogen, 3-methylcholanthrene (MC), in aryl hydrocarbon receptor responsive C57 BL/6 mice. We found that GT drinking itself induced hepatic CYP1As and enhanced MC-induced ethoxyresorufin-O-demethylase (EROD) activity (P<0.05). However, our studies of CYP1A monoclonal antibody and western blots revealed that the enhanced hepatic EROD activity by GT did not come from CYP1As. Therefore, our results suggest that GT may work to biotransform CYP1A inducing carcinogens into non-carcinogenic metabolites by modulation of other microsomal enzymes rather than CYP1As. In addition, the mechanism of GT chemoprevention may be different from that of GT components, such as polyphenols that reduce CYP1As activity.

5. Eur J Cancer Prev. 2003 Oct;12(5):383-90.

Protective effects of green tea extracts (polyphenon E and EGCG) on human cervical lesions.

Ahn WS, Yoo J, Huh SW, Kim CK, Lee JM, Namkoong SE, Bae SM, Lee IP.

Department of Obstetrics and Gynaecology.

SUMMARY: We investigated clinical efficacy of green tea extracts (polyphenon E; poly E and (-)-epigallocatechin-3-gallate [EGCG]) delivered in a form of ointment or capsule in patients with human papilloma virus (HPV) infected cervical lesions. Fifty-one patients with cervical lesions (chronic cervicitis, mild dysplasia, moderate dysplasia and severe dysplasia) were divided into four groups, as compared with 39 untreated patients as a control. Poly E ointment was applied locally to 27 patients twice a week. For oral delivery, a 200 mg of poly E or EGCG capsule was taken orally every day for eight to 12 weeks. In the study, 20 out of 27 patients (74%) under poly E ointment therapy showed a response. Six out of eight patients under poly E ointment plus poly E capsule therapy (75%) showed a response, and three out of six patients (50%) under poly E capsule therapy showed a response. Six out of 10 patients (60%) under EGCG capsule therapy showed a response. Overall, a 69% response rate (35/51) was noted for treatment with green tea extracts, as compared with a 10% response rate (4/39) in untreated controls (P<0.05). Thus, the data collected here demonstrated that green tea extracts in a form of ointment and capsule are effective for treating cervical lesions, suggesting that green tea extracts can be a potential therapy regimen for patients with HPV infected cervical lesions.

6. Phytomedicine. 2003;10(6-7):517-22.

Hydroxyl radical and hypochlorous acid scavenging activity of small centaury (Centaurium erythraea) infusion. A comparative study with green tea (Camellia sinensis).

Valentao P, Fernandes E, Carvalho F, Andrade PB, Seabra RM, Bastos ML.

CEQUP/Servico de Farmacognosia, Faculdade de Farmacia, Universidade do Porto, Porto, Portugal.

Small centaury (Centaurium erythraea Rafin.) is a herbal species with a long use in traditional medicine due to its digestive, stomachic, tonic, depurative, sedative and antipyretic properties. This species is reported to contain considerable amounts of polyphenolic compounds, namely xanthones and phenolic acids as the main constituents. Although the antiradicalar activity of some pure polyphenolic compounds is already known, it remains unclear how a complex mixture obtained from plant extracts functions against reactive oxygen species. Thus, the ability of small centaury infusion to act as a scavenger of the reactive oxygen species hydroxyl radical and hypochlorous acid was studied and compared with that of green tea (Camellia sinensis L.). Hydroxyl radical was generated in the presence of Fe3+-EDTA, ascorbate and H2O2 (Fenton system) and monitored by evaluating hydroxyl radical-induced deoxyribose degradation. The reactivity towards hypochlorous acid was determined by measuring the inhibition of hypochlorous acid-induced 5-thio-2-nitrobenzoic acid oxidation to 5,5'-dithiobis(2-nitrobenzoic acid). The obtained results demonstrate that small centaury infusion exhibits interesting antioxidant properties, expressed both by its capacity to effectively scavenge hydroxyl radical and hypochlorous acid, although with a lower activity against the second than that observed for green tea. Green tea exhibited a dual effect at the hydroxyl radical scavenging assay, stimulating deoxyribose degradation at lower dosages.

7. Phytomedicine. 2003;10(6-7):494-8.

Enhancement of neutral endopeptidase activity in SK-N-SH cells by green tea extract.

Melzig MF, Janka M.

Institut fur Pharmazie, Freie Universitat Berlin, Germany. melzig@zedat.fu-berlin.de

Green tea extract (EFLA85942) is able to induce specifically the neutral endopeptidase (NEP) activity and to inhibit the proliferation of SK-N-SH cells; the angiotensin-converting enzyme (ACE) activity is not influenced under the same conditions. The treatment of the cells with arabinosylcytosine and green tea extract results in a strong enhancement of cellular NEP activity whereas cellular ACE activity was not changed significantly, indicating a green tea extract-specific regulation of NEP expression. Because of its role in the degradation of amyloid beta peptides this enzyme induction of NEP by long term treatment with green tea extract may have a beneficial effect regarding the prevention of forming amyloid plaques.

8. Br J Pharmacol. 2003 Oct;140(3):487-499. Epub 2003 Aug 26.

Interactions of androgens, green tea catechins and the antiandrogen flutamide with the external glucose-binding site of the human erythrocyte glucose transporter GLUT1.

Naftalin RJ, Afzal I, Cunningham P, Halai M, Ross C, Salleh N, Milligan SR.

New Hunt's House, King's College London, Guys Campus, London SE1 1UL.

This study investigates the effects of androgens, the antiandrogen flutamide and green tea catechins on glucose transport inhibition in human erythrocytes. These effects may relate to the antidiabetogenic effects of green tea. Testosterone, 4-androstene-3,17-dione, dehydroepiandrosterone (DHEA) and DHEA-3-acetate inhibit glucose exit from human erythrocytes with half-maximal inhibitions (Ki) of 39.2+/-8.9, 29.6+/-3.7, 48.1+/-10.2 and 4.8+/-0.98 microm, respectively. The antiandrogen flutamide competitively relieves these inhibitions and of phloretin. Dehydrotestosterone has no effect on glucose transport, indicating the differences between androgen interaction with GLUT1 and human androgen receptor (hAR). Green tea catechins also inhibit glucose exit from erythrocytes. Epicatechin 3-gallate (ECG) has a Ki ECG of 0.14+/-0.01 microm, and epigallocatechin 3-gallate (EGCG) has a Ki EGCG of 0.97+/-0.13 microm. Flutamide reverses these effects. Androgen-screening tests show that the green tea catechins do not act genomically. The high affinities of ECG and EGCG for GLUT1 indicate that this might be their physiological site of action. There are sequence homologies between GLUT1 and the ligand-binding domain (LBD) of hAR containing the amino-acid triads Arg 126, Thr 30 and Asn 288, and Arg 126, Thr 30 and Asn 29, with similar 3D topology to the polar groups binding 3-keto and 17-beta OH steroid groups in hAR LBD. These triads are appropriately sited for competitive inhibition of glucose import at the external opening of the hydrophilic pore traversing GLUT1.British Journal of Pharmacology (2003) 140, 487-499. doi:10.1038/sj.bjp.0705460

9. Clin Cancer Res. 2003 Aug 15;9(9):3312-9.

Pharmacokinetics and safety of green tea polyphenols after multiple-dose administration of epigallocatechin gallate and polyphenon E in healthy individuals.

Chow HH, Cai Y, Hakim IA, Crowell JA, Shahi F, Brooks CA, Dorr RT, Hara Y, Alberts DS.

Arizona Cancer Center, The University of Arizona, Tucson, Arizona 85724, USA.

PURPOSE: Green tea and green tea polyphenols have been shown to possess cancer preventive activities in preclinical model systems. In preparation for future green tea intervention trials, we have conducted a clinical study to determine the safety and pharmacokinetics of green tea polyphenols after 4 weeks of daily p.o. administration of epigallocatechin gallate (EGCG) or Polyphenon E (a defined, decaffeinated green tea polyphenol mixture). In an exploratory fashion, we have also determined the effect of chronic green tea polyphenol administration on UV-induced erythema response. EXPERIMENTAL DESIGN: Healthy participants with Fitzpatric skin type II or III underwent a 2-week run-in period and were randomly assigned to receive one of the five treatments for 4 weeks: 800 mg EGCG once/day, 400 mg EGCG twice/day, 800 mg EGCG as Polyphenon E once/day, 400 mg EGCG as Polyphenon E twice/day, or a placebo once/day (8 subjects/group). Samples were collected and measurements performed before and after the 4-week treatment period for determination of safety, pharmacokinetics, and biological activity of green tea polyphenol treatment. RESULTS: Adverse events reported during the 4-week treatment period include excess gas, upset stomach, nausea, heartburn, stomach ache, abdominal pain, dizziness, headache, and muscle pain. All of the reported events were rated as mild events. For most events, the incidence reported in the polyphenol-treated groups was not more than that reported in the placebo group. No significant changes were observed in blood counts and blood chemistry profiles after repeated administration of green tea polyphenol products. There was a >60% increase in the area under the plasma EGCG concentration-time curve after 4 weeks of green tea polyphenol treatment at a dosing schedule of 800 mg once daily. No significant changes were observed in the pharmacokinetics of EGCG after repeated green tea polyphenol treatment at a regimen of 400 mg twice daily. The pharmacokinetics of the conjugated metabolites of epigallocatechin and epicatechin were not affected by repeated green tea polyphenol treatment. Four weeks of green tea polyphenol treatment at the selected dose and dosing schedule did not provide protection against UV-induced erythema. CONCLUSIONS: We conclude that it is safe for healthy individuals to take green tea polyphenol products in amounts equivalent to the EGCG content in 8-16 cups of green tea once a day or in divided doses twice a day for 4 weeks. There is a >60% increase in the systemic availability of free EGCG after chronic green tea polyphenol administration at a high daily bolus dose (800 mg EGCG or Polyphenon E once daily).

10. Clin Exp Allergy. 2003 Sep;33(9):1252-5.

Green tea-induced asthma: relationship between immunological reactivity, specific and non-specific bronchial responsiveness.

Shirai T, Reshad K, Yoshitomi A, Chida K, Nakamura H, Taniguchi M.

Department of Internal Medicine, Fujinomiya City General Hospital, Fujinomiya, Japan. fmyhsp@lilac.ocn.ne.jp

BACKGROUND: The relationships between immunological reactivity and bronchial responsiveness to allergen and non-specific bronchial responsiveness are unclear in occupational asthma caused by low molecular weight substances. OBJECTIVE: We assessed the above relationships in green tea-induced asthma, an occupational asthma of green tea factory workers, in which epigallocatechin gallate (EGCg), a low molecular weight component of green tea leaves, is the causative agent. METHODS: Subjects consisted of 21 patients suspected of having green tea-induced asthma, on whom skin test and inhalation challenge with EGCg were performed. The skin sensitivity or end-point titration to EGCg as a measure of immunological reactivity, together with the provocative concentrations causing a 20% or greater fall in forced expiratory volume in 1 s (PC20) of EGCg and methacholine, were determined. RESULTS: We found that 11 patients had green tea-induced asthma, with immediate asthmatic reactions in eight and dual asthmatic reactions in three. We also found that 11 of 13 patients (85%) with immunological reactivity and bronchial hyper-responsiveness to methacholine experienced an asthmatic reaction and that no subject without immunological reactivity reacted. There were significant correlations among skin sensitivity, EGCg PC20 and methacholine PC20. Multiple linear regression analysis showed the relationship: log (EGCg PC20)=0.42 log (skin sensitivity)+1.17 log (methacholine PC20)+0.93 (r=0.796, P<0.05). CONCLUSION: It is concluded that bronchial responsiveness to EGCg can be highly satisfactorily predicted by skin sensitivity to EGCg and bronchial responsiveness to methacholine.

11. J Pharmacol Exp Ther. 2003 Oct;307(1):230-6. Epub 2003 Sep 03.

Green tea polyphenol causes differential oxidative environments in tumor versus normal epithelial cells.

Yamamoto T, Hsu S, Lewis J, Wataha J, Dickinson D, Singh B, Bollag WB, Lockwood P, Ueta E, Osaki T, Schuster G.

Kochi Medical School, Japan.

Green tea polyphenols (GTPPs) are considered beneficial to human health, especially as chemopreventive agents. Recently, cytotoxic reactive oxygen species (ROS) were identified in tumor and certain normal cell cultures incubated with high concentrations of the most abundant GTPP, (-)-epigallocatechin-3-gallate (EGCG). If EGCG also provokes the production of ROS in normal epithelial cells, it may preclude the topical use of EGCG at higher doses. The current study examined the oxidative status of normal epithelial, normal salivary gland, and oral carcinoma cells treated with EGCG, using ROS measurement and catalase and superoxide dismutase activity assays. The results demonstrated that high concentrations of EGCG induced oxidative stress only in tumor cells. In contrast, EGCG reduced ROS in normal cells to background levels. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and 5-bromodeoxyuridine incorporation data were also compared between the two oral carcinoma cell lines treated by EGCG, which suggest that a difference in the levels of endogenous catalase activity may play an important role in reducing oxidative stress provoked by EGCG in tumor cells. It is concluded that pathways activated by GTPPs or EGCG in normal epithelial versus tumor cells create different oxidative environments, favoring either normal cell survival or tumor cell destruction. This finding may lead to applications of naturally occurring polyphenols to enhance the effectiveness of chemo/radiation therapy to promote cancer cell death while protecting normal cells.

12. Biol Pharm Bull. 2003 Sep;26(9):1235-8.

Inhibitory effect of green tea polyphenols on membrane-type 1 matrix metalloproteinase, MT1-MMP.

Oku N, Matsukawa M, Yamakawa S, Asai T, Yahara S, Hashimoto F, Akizawa T.

Department of Medical Biochemistry and COE Program in the 21st Century, University of Shizuoka, School of Pharmaceutical Sciences.

Matrix metalloproteinases (MMPs), especially membrane-type 1 matrix metalloproteinase (MT1-MMP), which generates an active form of MMP-2 from proMMP-2, are deeply involved in angiogenesis as well as in tumor cell migration and metastasis. To obtain a specific inhibitor for MT1-MMP, we screened a number of natural and synthetic compounds using recombinant human MMP-2, MMP-7, and soluble MT1-MMP in a fluorogenic peptide cleavage assay. (-)-Epigallocatechin 3-O-gallate (EGCG) followed by (-)-epigallocatechin 3,5-di-O-gallate and epitheaflagallin 3-O-gallate, was found to have potent and distinct inhibitory activity against MT1-MMP. Therefore, we investigated the effect of EGCG on the suppression of MMP-2 activation as determined by gelatin zymography, and observed that the active form of MMP-2 in the conditioned medium of human umbilical vein endothelial cells was decreased in the presence of EGCG. The results suggest the possibility that tea polyphenols suppress tumor growth through the suppression of angiogenesis.

13. Sichuan Da Xue Xue Bao Yi Xue Ban. 2003 Apr;34(2):303-5.

[Protective effects of green tea on mice with the irradiating damage induced by gamma-ray]

[Article in Chinese]

Wang Z, Zeng L, Xiao Y, Lu S, Gao X.

Department of Nutrition and Food Hygiene, West China School of Public Health, Sichuan University, Chengdu 610041, China.

OBJECTIVE: To evaluate the protective effects of green tea on mice with the irradiating damage induced by 60Co-gamma-ray. METHODS: Thirty-five mice were divided into normal control group, irradiating control group and three experiment groups. The mice of the experiment groups drank in water soluble extractives of green tea (1.25%, 2.5%, 5%) for two weeks. Then all animals were irradiated by 60Co-gamma-ray except those of the normal control group. The animals of three experiment groups continued drinking the water soluble extractives of green tea for one week, after that all mice of the five groups were killed. The levels of malondiadehyde (MDA) and the activities of superoxide dismutase (SOD) in serums, the optical density (OD) value of DNA and the number of karyota of femur, the frequency of micronuclei in polychromatophilic erythrocytes of bone marrow in mice of all groups were measured. RESULTS: Compared with the measurements in the irradiating control group, the level of MDA in serums and the frequency of micronuclei in polychromatophilic erythrocytes of bone marrow in the three experiment groups were decreased significantly (P < 0.05), while the activities of SOD in serums, the OD value of DNA and the number of karyota of femur in mice of the three experiment groups were increased significantly (P < 0.05). CONCLUSION: The water soluble extractives of green tea have protective effects on mice with the irradiating damage induced by gamma-ray.

14. Int J Cancer. 2003 Oct 10;106(6):871-8.

Green tea catechins inhibit VEGF-induced angiogenesis in vitro through suppression of VE-cadherin phosphorylation and inactivation of Akt molecule.

Tang FY, Nguyen N, Meydani M.

Vascular Biology Laboratory, JM USDA-Human Nutrition Research Center on Aging at Tufts University, Boston, MA 02111, USA.

Studies have indicated that the consumption of green tea is associated with a reduced risk of developing certain forms of cancer and angiogenesis. The mechanism of inhibition of angiogenesis by green tea or its catechins, however, has not been well-established. Vascular endothelial (VE)-cadherin, an adhesive molecule located at the site of intercellular contact, is involved in cell-cell recognition during vascular morphogenesis. The extracellular domain of VE-cadherin mediates initial cell adhesion, whereas the cytosolic tail binding with beta-catenin is required for interaction with the cytoskeleton and junctional strength. Therefore, the cadherin-catenin adhesion system is implicated in cell recognition, differentiation, growth and migration of capillary endothelium. Using tube formation of human microvascular endothelial cells (HMVEC) in culture as an in vitro model of angiogenesis, we reported that vascular endothelial growth factor (VEGF)-induced tube formation is inhibited by anti-VE-cadherin antibody and dose-dependently by green tea catechins. We also demonstrated here that inhibition of tube formation by epigallocatechin gallate (EGCG), one of the green tea catechins, is in part mediated through suppression of VE-cadherin tyrosine phosphorylation and inhibition of Akt activation during VEGF-induced tube formation. These findings indicate that VE-cadherin and Akt, known downstream proteins in VEGFR-2-mediated cascade, are the new-targeted proteins by which green tea catechins inhibit angiogenesis. Copyright 2003 Wiley-Liss, Inc.

15. J Urol. 2003 Sep;170(3):773-6.

Inhibition of bladder tumor growth by the green tea derivative epigallocatechin-3-gallate.

Kemberling JK, Hampton JA, Keck RW, Gomez MA, Selman SH.

Department of Urology, Medical College of Ohio, 3065 Arlington Avenue, Dowling Hall 2170, Toledo, OH 43614-5807, USA.

PURPOSE: We evaluated the green tea derivative epigallocatechin-3-gallate (EGCG) as an intravesical agent for the prevention of transitional cell tumor implantation. MATERIALS AND METHODS: In vitro studies were performed in the AY-27 rat transitional cell cancer and the L1210 mouse leukemia cell lines. Cells were exposed to increasing concentrations of EGCG for 30 minutes to 48 hours. Surviving cell colonies were then determined. A DNA ladder assay was performed in the 2 cell lines. Fisher 344 rats were used for in vivo studies with an intravesical tumor implantation model. Group 1 (12 rats) served as a control (tumor implantation and medium wash only). In group 2 (28 rats) 200 microM EGCG were instilled intravesically 30 minutes after tumor implantation. Rats were sacrificed 3 weeks following treatment. Gross and histological analyses were then performed on the bladders. RESULTS: At 6.0 x 104 cells per 100 mm dish a time dose dependent response was observed. After 2 hours of treatment with EGCG 100% cell lethality of the AY-27 cell line occurred at concentrations greater than 100 microM. Strong banding on the DNA ladder assay was seen with the L1210 mouse leukemia cell line. Only weak banding patterns were found in the AY-27 cell line treated with EGCG (100 and 200 microM) for 24 hours. All 12 controls were successfully implanted with tumors. In group 2 (EGCG instillation) 18 of the 28 animals (64%) were free of tumor (Fisher's exact test p = 0.001). CONCLUSIONS: The clonal assays showed a time dose related response to EGCG. Intravesical instillation of EGCG inhibits the growth of AY-27 rat transitional cells implanted in this model.

16. J Neurochem. 2003 Sep;86(5):1189-200.

Green tea polyphenols enhance sodium nitroprusside-induced neurotoxicity in human neuroblastoma SH-SY5Y cells.

Zhang Y, Zhao B.

Laboratory of Visual Information Processing, Institute of Biophysics, Academia Sinica, 15 Datun Road, Chaoyang District, Beijing 100101, China.

Oxidative stress is a main mediator in nitric oxide (NO) -induced neurotoxicity and has been implicated in the pathogenesis of many neurodegenerative disorders. Green tea polyphenols are usually expected as potent chemo-preventive agents due to their ability of scavenging free radicals and chelating metal ions. However, not all the actions of green tea polyphenols are necessarily beneficial. In the present study, we demonstrated that higher-concentration green tea ployphenols significantly enhanced the neurotoxicity by treatment of sodium nitroprusside (SNP), a nitric oxide donor. SNP induced apoptosis in human neuroblastoma SH-SY5Y cells in a concentration and time-dependent manner, as estimated by cell viability assessment, FACScan analysis and DNA fragmentation assay, whereas treatment with green tea polyphenols alone had no effect on cell viability. Pre-treatment with lower-dose green tea polyphenols (50 and 100 microm) had only a slightly deleterious effect in the presence of SNP, while higher-dose green tea polyphenols (200 and 500 microm) synergistically damaged the cells severely. Further research showed that co-incubation of green tea polyphenols and SNP caused loss of mitochondrial membrane potential, depletion of intracellular GSH and accumulation of reactive oxygen species, and exacerbated NO-induced neuronal apoptosis via a Bcl-2 sensitive pathway.

17. Brain Res Bull. 2003 Aug 30;61(4):399-406.

Effects of delayed administration of (-)-epigallocatechin gallate, a green tea polyphenol on the changes in polyamine levels and neuronal damage after transient forebrain ischemia in gerbils.

Lee SY, Kim CY, Lee JJ, Jung JG, Lee SR.

Department of Pharmacology, Kyungpook National University, 700-422 Taegu, South Korea.

(-)-Epigallocatechin gallate has a potent antioxidant property and can reduce free radical-induced lipid peroxidation as a green tea polyphenol. In previous study, systemic administration of (-)-epigallocatechin gallate immediately after ischemia has been shown to inhibit the hippocampal neuronal damage in the gerbil model of global ischemia. Polyamines are thought to be important in the generation of brain edema and neuronal cell damage associated with various types of excitatory neurotoxicity. We examined the effects of delayed administration of (-)-epigallocatechin gallate on the changes in polyamine levels and neuronal damage after transient global ischemia in gerbils. To produce transient global ischemia, both common carotid arteries were occluded for 3 min with micro-clips. The gerbils were treated with (-)-epigallocatechin gallate (50 mg/kg, i.p.) at 1 or 3 h after ischemia. The polyamines; putrescine, spermidine, and spermine levels were examined using high performance liquid chromatography in the cerebral cortex and hippocampus 24 h after ischemia. Putrescine levels in the cerebral cortex and hippocampus were increased significantly after ischemia and the delayed administrations of (-)-epigallocatechin gallate (1 or 3 h after ischemia) attenuated the increases. Only minor changes were noted in the spermidine and spermine levels after ischemia. In histology, neuronal injuries in the hippocampal CA1 regions were evaluated quantitatively 5 days after ischemia. (-)-Epigallocatechin gallate administered 1 h or 3 after ischemia significantly reduced hippocampal neuronal damage. The present results show that the delayed administrations of (-)-epigallocatechin gallate inhibit the transient global ischemia-induced increase of putrescine levels in the cerebral cortex and hippocampus. (-)-Epigallocatechin gallate is neuroprotective against neuronal damage even when administered up to 3 h after global ischemia. These findings suggest that (-)-epigallocatechin gallate may be promising in the acute treatment of stroke.

18. Recent Results Cancer Res. 2003;163:165-71; discussion 264-6.

Chemoprevention of nonmelanoma skin cancer: experience with a polyphenol from green tea.

Linden KG, Carpenter PM, McLaren CE, Barr RJ, Hite P, Sun JD, Li KT, Viner JL, Meyskens FL.

Department of Dermatology, University of California, Irvine, 101 The City Drive, Orange, CA 92868, USA.

Nonmelanoma skin cancer is extremely common and is increasing in incidence. It would be very useful to have forms of therapy that would prevent precancerous changes from going on to form cancer, or to reverse the precancerous changes. Epidemiologic evidence in humans, in vitro studies on human cells, and clinical experiments in animals have identified polyphenol compounds found in tea to be possibly useful in reducing the incidence of various cancers, including skin cancer. To examine the potential for a polyphenol from green tea, epigallocatechin gallate, to act as a chemopreventive agent for nonmelanoma skin cancer, a randomized, double-blind, placebo-controlled phase II clinical trial of topical epigallocatechin gallate in the prevention of nonmelanoma skin cancer was performed.

19. FASEB J. 2003 Oct;17(13):1913-5. Epub 2003 Aug 01.

Dual mechanisms of green tea extract (EGCG)-induced cell survival in human epidermal keratinocytes.

Chung JH, Han JH, Hwang EJ, Seo JY, Cho KH, Kim KH, Youn JI, Eun HC.

Department of Dermatology, Seoul National University College of Medicine, and Laboratory of Cutaneous Aging Research, Clinical Research Institute, Seoul National University Hospital, Seoul, Korea.

Beneficial effects attributed to green tea, such as its anticancer and antioxidant properties, may be mediated by (-)-epigallocatechin-3-gallate (EGCG). In this study, the effects of EGCG on cell proliferation and UV-induced apoptosis were investigated in normal epidermal keratinocytes. When topically applied to aged human skin, EGCG stimulated the proliferation of epidermal keratinocytes, which increased the epidermal thickness. In addition, this topical application also inhibited the UV-induced apoptosis of epidermal keratinocytes. EGCG was found to increase the phosphorylation of Bad protein at the Ser112 and Ser136. Moreover, EGCG-induced Erk phosphorylation was found to be critical for the phosphorylation of Ser112 in Bad protein, and the EGCG-induced activation of the Akt pathway was found to be involved in the phosphorylation of Ser136. Furthermore, EGCG increased Bcl-2 expression but decreased Bax expression, causing an increase in the Bcl-2-to-Bax ratio. In addition, we demonstrate the differential growth inhibitory effects of EGCG on cancer cells. In conclusion, this study demonstrates that EGCG promotes keratinocyte survival and inhibits the UV-induced apoptosis via two mechanisms: by phosphorylating Ser112 and Ser136 of Bad protein through Erk and Akt pathways, respectively, and by increasing the Bcl-2-to-Bax ratio. Moreover, these two proposed mechanisms of EGCG-induced cell proliferation may differ kinetically to promote keratinocyte survival.

20. Biochem Biophys Res Commun. 2003 Aug 15;308(1):64-7.

Effect of green tea polyphenols on angiogenesis induced by an angiogenin-like protein.

Maiti TK, Chatterjee J, Dasgupta S.

Department of Chemistry, Indian Institute of Technology, Kharagpur 721302, West Bengal, India.

Angiogenesis is a fundamental process by which new blood vessels are formed. The angiogenesis process is induced by several growth factors. Among them angiogenin is the most potent blood vessel inducer known. In this paper, we have investigated the effect of green tea polyphenols, mainly the catechins, on an angiogenin-like protein induced angiogenesis process. The angiogenin-like protein was isolated from goat serum and the effect of green tea components was tested by the chicken chorioallantoic membrane (CAM) assay. The results show that green tea components are capable of reducing the vascularization on CAM that is induced by the angiogenin-like protein.

21. Eur J Epidemiol. 2003;18(5):401-5.

Relation of coffee, green tea, and caffeine intake to gallstone disease in middle-aged Japanese men.

Ishizuk H, Eguchi H, Oda T, Ogawa S, Nakagawa K, Honjo S, Kono S.

Department of Preventive Medicine, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan.

A possible protective effect of coffee or caffeine intake in the formation of gallstones has been suggested in some epidemiological studies. We examined the relation of coffee, green tea, and caffeine intake to gallstone disease in middle-aged Japanese men, distinguishing known gallstones from unknown diagnosed gallstones. Study subjects were 174 cases of gallstones as determined by ultrasonography, 104 cases of postcholecystectomy, and 6889 controls of normal gallbladder in the total of 7637 men who received a health examination at four hospitals of the Self-Defense Forces (SDF). Of the 174 cases of prevalent gallstones, 50 had been aware of having gallstones. Previously diagnosed gallstones and postcholecystectomy were combined as known gallstone disease. The consumption of coffee and green tea was ascertained by a self-administered questionnaire, and caffeine intake was estimated. Statistical adjustment was done for body mass index, smoking, alcohol use, rank in the SDF, and hospital. Coffee and caffeine intake were associated each with a statistically significant increase in the prevalence odds of known gallstone disease, but unrelated to newly diagnosed gallstones. Adjusted odds ratios of known gallstone disease were 1.7 (95% confidence interval [CI] 1.1-2.8) for coffee consumption of five cups or more per day vs. no consumption and 2.2 (95% CI: 1.3-3.7) for caffeine intake of 300 mg/day or more vs. less than 100 mg/day. The consumption of green-tea showed no material association with either unknown gallstones or known gallstone disease. The findings do not support a hypothesis that coffee drinking may be protective against gallstone formation.

22. Nutr Cancer. 2003;45(2):226-35.

Catechin content of 18 teas and a green tea extract supplement correlates with the antioxidant capacity.

Henning SM, Fajardo-Lira C, Lee HW, Youssefian AA, Go VL, Heber D.

UCLA Center for Human Nutrition, School of Medicine, Warren Hall 14-166, 900 Veteran Avenue, Los Angeles, CA 90095, USA. shenning@mednet.ucla.edu

Our literature review of currently available data in the area of tea and cancer prevention demonstrated that there is more conclusive evidence for the chemopreventive effect of green tea compared with black tea. We suggest that this is due to a large variation of the flavanol content in tea, which is not taken into consideration in most of the epidemiological studies. It was the purpose of this study to determine the flavanol content of various teas and tea products and to correlate it with their radical scavenging activity. A modified oxygen radical absorbance capacity (ORAC) assay at pH 5.5 was utilized. The total flavavol content varied from 21.2 to 103.2 mg/g for regular teas and from 4.6 to 39.0 mg/g for decaffeinated teas. The ORAC value varied from 728 to 1686 trolox equivalents/g tea for regular teas and from 507 to 845 trolox equivalents/g for decaffeinated teas. There was a significant correlation of flavanol content to ORAC value (r = 0.79, P = 0.0001) for the teas and green tea extract. The large variation in flavanol content and ORAC value among various brands and types of tea provides critical information for investigators using tea in studies of nutrition and cancer prevention.

23. Zhonghua Yu Fang Yi Xue Za Zhi. 2003 May;37(3):171-3.

[Study on the protective effect of green tea on gastric, liver and esophageal cancers]

[Article in Chinese]

Mu LN, Zhou XF, Ding BG, Wang RH, Zhang ZF, Jiang QW, Yu SZ.

School of Public Health, Fudan University, Shanghai 200032, China.

OBJECTIVE: To assess the protective effect of drinking green tea on the development of gastric, liver and esophageal cancers. METHODS: A population based study was conducted in Taixing, Jiangsu province, including 206, 204, 218 cases, respectively, and 415 population controls. RESULTS: Green tea decreased the development of gastric cancer risk by 40%. Dose-response relationships were observed between the length of time, concentration and quantity of green tea drinking and its protective effects on gastric cancer. For individuals who drink green tea for more than 250 g per month, the risk of gastric cancer reduced about 60%. Green tea might have protective effect on liver cancer. However, no protective effect of green tea was observed on esophageal cancer. CONCLUSION: Green tea drinking might be a protective factor for gastric cancer. However, the protective effects of green tea on liver and esophageal cancer were not obvious.

24. Drugs Aging. 2003;20(10):711-21.

Potential therapeutic properties of green tea polyphenols in Parkinson's disease.

Pan T, Jankovic J, Le W.

Department of Neurology, Baylor College of Medicine, Houston, Texas 77030, USA.

Tea is one of the most frequently consumed beverages in the world. It is rich in polyphenols, a group of compounds that exhibit numerous biochemical activities. Green tea is not fermented and contains more catechins than black tea or oolong tea. Although clinical evidence is still limited, the circumstantial data from several recent studies suggest that green tea polyphenols may promote health and reduce disease occurrence, and possibly protect against Parkinson's disease and other neurodegenerative diseases.Green tea polyphenols have demonstrated neuroprotectant activity in cell cultures and animal models, such as the prevention of neurotoxin-induced cell injury. The biological properties of green tea polyphenols reported in the literature include antioxidant actions, free radical scavenging, iron-chelating properties, (3)H-dopamine and (3)H-methyl-4-phenylpyridine uptake inhibition, catechol-O-methyltransferase activity reduction, protein kinase C or extracellular signal-regulated kinases signal pathway activation, and cell survival/cell cycle gene modulation. All of these biological effects may benefit patients with Parkinson's disease.Despite numerous studies in recent years, the understanding of the biological activities and health benefits of green tea polyphenols is still very limited. Further in-depth studies are needed to investigate the safety and efficacy of green tea in humans and to determine the different mechanisms of green tea in neuroprotection.

25. Curr Drug Targets Immune Endocr Metabol Disord. 2003 Sep;3(3):234-42.

Skin photoprotection by green tea: antioxidant and immunomodulatory effects.

Katiyar SK.

Department of Dermatology, University of Alabama at Birmingham, Birmingham, AL 35294, USA. skatiyar@uab.edu

Because of a characteristic aroma and health benefits, green tea is consumed worldwide as a popular beverage. The epicatechin derivatives, commonly called polyphenols, present in green tea possess antioxidant, anti-inflammatory and anti-carcinogenic properties. The major and most highly chemopreventive constituent in green tea responsible for the biochemical or pharmacological effects is (-)-epigallocatechin-3-gallate (EGCG). Epidemiological, clinical and biological studies have implicated that solar ultraviolet (UV) light is a complete carcinogen and repeated exposure can lead to the development of various skin disorders including melanoma and nonmelanoma skin cancers. We and others have shown that topical treatment or oral consumption of green tea polyphenols (GTP) inhibit chemical carcinogen- or UV radiation-induced skin carcinogenesis in different laboratory animal models. Topical treatment of GTP and EGCG or oral consumption of GTP resulted in prevention of UVB-induced inflammatory responses, immunosuppression and oxidative stress, which are the biomarkers of several skin disease states. Topical application of GTP and EGCG prior to exposure of UVB protects against UVB-induced local as well as systemic immune suppression in laboratory animals, which was associated with the inhibition of UVB-induced infiltration of inflammatory leukocytes. Prevention of UVB-induced suppression of immune responses by EGCG was also associated with the reduction in immunosuppressive cytokine interleukin (IL)-10 production at UV irradiated skin and draining lymph nodes, whereas IL-12 production was significantly enhanced in draining lymph nodes. Antioxidant and anti-inflammatory effects of green tea were also observed in human skin. Treatment of EGCG to human skin resulted in the inhibition of UVB-induced erythema, oxidative stress and infiltration of inflammatory leukocytes. We also showed that treatment of GTP to human skin prevents UVB-induced cyclobutane pyrimidine dimers formation, which are considered to be mediators of UVB-induced immune suppression and skin cancer induction. The in vitro and in vivo animal and human studies suggest that green tea polyphenols are photoprotective in nature, and can be used as pharmacological agents for the prevention of solar UVB light-induced skin disorders including photoaging, melanoma and nonmelanoma skin cancers after more clinical trials in humans.

26. Chem Res Toxicol. 2003 Jul;16(7):865-72.

Identification of potential aryl hydrocarbon receptor antagonists in green tea.

Palermo CM, Hernando JI, Dertinger SD, Kende AS, Gasiewicz TA.

Department of Environmental Medicine, University of Rochester, Rochester, New York 14642, USA.

Previous investigations have implicated green tea to exert chemopreventive effects in animal models of chemical carcinogenesis, including polycyclic aryl hydrocarbon-induced cancers. In an effort to understand the compound(s) responsible for this protection, the effects of green tea extracts (GTE) and individual green tea catechins on aryl hydrocarbon receptor (AhR) gene induction were determined. Green tea (GT) was organically extracted and subsequently fractionated by column chromatography. The chemical composition of each fraction was determined by NMR. Several fractions inhibited tetrachlorodibenzo-p-dioxin-induced transcription of a dioxin responsive element-dependent luciferase reporter in stably transfected mouse hepatoma cells in a concentration-dependent manner. To determine the GT component(s) responsible for the observed effects, individual catechins were tested in the luciferase reporter system at concentrations found within the active fractions. Of the catechins tested, epigallocatechingallate (EGCG) and epigallocatechin (EGC) were the most potent antagonists, with IC(50) values of 60 and 100 microM, respectively. Re-creation of the active fractions using commercially available catechins further confirmed the identification of EGCG and EGC as the active AhR antagonists in green tea. These data suggest that EGCG and EGC are capable of altering AhR transcription and are responsible for most, if not all, of the AhR antagonist activity of GTE.

27. Life Sci. 2003 Aug 8;73(12):1479-89.

Action of green tea catechin on bone metabolic disorder in chronic cadmium-poisoned rats.

Choi JH, Rhee IK, Park KY, Park KY, Kim JK, Rhee SJ.

Department of Food Science and Nutrition, Catholic University of Daegu, 712-702, South Korea.

The purpose of this study was to investigate the effects of green tea catechin on bone metabolic disorders and its mechanism in chronic cadmium-poisoned rats. Sprague-Dawley male rats weighing 100+/-10 g were randomly assigned to one control group and three cadmium-poisoned groups. The cadmium groups included a catechin free diet (Cd-0C) group, a 0.25% catechin diet (Cd-0.25C) group and a 0.5% catechin diet (Cd-0.5C) group according to their respective levels of catechin supplement. After 20 weeks, the deoxypyridinoline and crosslink values measured in urine were significantly increased in the Cd-0C group. Cadmium intoxication seemed to lead to an increase in bone resorption. In the catechin supplemented group (Cd-0.5C group), these urinary bone resorption marks, were decreased. The serum osteocalcin content in the cadmium-poisoned group was significantly increased as compared with the control group. In the catechin supplemented group serum osteocalcin content values were lower than the control group. The cadmium-intoxicated group (Cd-0C group), had lower bone mineral density than the control group (total body, vertebra, pelvis, tibia and femur). The catechin supplement increased bone mineral density to about the same as the control group. Bone mineral content showed a similar trend to total bone mineral density. Therefore, the bone mineral content of the Cd-0C group at the 20th week was significantly lower than the control group. The catechin supplemented group (Cd-0.5C group) was about the same as the control group. The cause of decreasing bone mineral density and bone mineral content by cadmium poisoning was due to the fast bone turnover rate, where bone resorption occurred at a higher rate than bone formation. The green tea catechin aided in normalizing bone metabolic disorders in bone mineral density, bone mineral content and bone calcium content caused by chronic cadmium intoxication.

28. Ann N Y Acad Sci. 2003 May;993:351-61; discussion 387-93.

Gene and protein expression profiles of anti- and pro-apoptotic actions of dopamine, R-apomorphine, green tea polyphenol (-)-epigallocatechine-3-gallate, and melatonin.

Weinreb O, Mandel S, Youdim MB.

Eve Topf, Haifa, Israel.

Significant evidence has been provided to support the hypothesis that oxidant stress may be responsible for degeneration of dopaminergic neurons in the substantia nigra pars compacta in Parkinson's disease. Dopamine (DA), R-apomorphine (R-APO), green tea polyphenol (-)-epigallocatechine-3-gallate (EGCG), and melatonin are neuroprotective and radical scavenger compounds. The aim of this study was to establish the mechanism of the concentration-dependent neuroprotective and pro-apoptotic action of these drugs via gene expression and protein determination. cDNA microarrays provide new prospects to study and identify various mechanisms of drug action. We employed this technique for the study reported in this paper. Total RNA was extracted from SH-SY5Y cells exposed to low neuroprotective and high toxic concentrations of the drugs, followed by synthesis of cDNA, and hybridization to a microarray membrane related to apoptosis, survival, and cell cycle pathways. We demonstrated a concentration and time-dependent correlation between R-APO, DA, EGCG, and melatonin in modulation of cell survival/cell death-related gene pathways. The results were confirmed by quantitative real-time PCR and protein profiles. Unlike the effects of low concentrations (1-10 micro M), where an antiapoptotic response was manifest, a proapoptotic pattern of gene expression was observed at high toxic concentrations (50-500 micro M) of the antioxidants (e.g., increase in caspases, fas, and gadd45). Our results have provided novel insights into the gene mechanisms involved in both the neuroprotective and proapoptotic activities of neuroprotective drugs. We have shown that DA, R-APO, EGCG, and melatonin exhibit similar gene expression and protein profiles.

29. Life Sci. 2003 Aug 1;73(11):1383-92.

Stimulatory effect of oral administration of green tea and caffeine on locomotor activity in SKH-1 mice.

Michna L, Lu YP, Lou YR, Wagner GC, Conney AH.

Joint Graduate Program in Toxicology, Rutgers, The State University of New Jersey and The University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway, NJ, USA.

Administration of green tea or caffeine was shown previously to inhibit ultraviolet B light-induced carcinogenesis in SKH-1 mice, and this effect was associated with a reduction in dermal fat. In the present study, oral administration of 0.6% green tea (6 mg tea solids/ml) or 0.04% caffeine (0.4 mg/ml; equivalent to the amount of caffeine in 0.6% green tea) as the sole source of drinking fluid to SKH-1 mice for 15 weeks increased total 24 hr locomotor activity by 47 and 24%, respectively (p<0.0001). Oral administration of 0.6% decaffeinated green tea (6 mg tea solids/ml) for 15 weeks increased locomotor activity by 9% (p<0.05). The small increase in locomotor activity observed in mice treated with decaffeinated green tea may have resulted from the small amounts of caffeine still remaining in decaffeinated green tea solutions (0.047 mg/ml). The stimulatory effects of orally administered green tea and caffeine on locomotor activity were paralleled by a 38 and 23% increase, respectively, in the dermal muscle layer thickness. In addition, treatment of the mice with 0.6% green tea or 0.04% caffeine for 15 weeks decreased the weight of the parametrial fat pad by 29 and 43%, respectively, and the thickness of the dermal fat layer was decreased by 51 and 47%, respectively. These results indicate that oral administration of green tea or caffeine to SKH-1 mice increases locomotor activity and muscle mass and decreases fat stores. The stimulatory effect of green tea and caffeine administration on locomotor activity described here may contribute to the effects of green tea and caffeine to decrease fat stores and to inhibit carcinogenesis induced by UVB in SKH-1 mice.

30. Life Sci. 2003 Jul 25;73(10):1299-313.

Green tea extract inhibits angiogenesis of human umbilical vein endothelial cells through reduction of expression of VEGF receptors.

Kojima-Yuasa A, Hua JJ, Kennedy DO, Matsui-Yuasa I.

Department of Food and Human Health Sciences, Graduate School of Human Life Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan. kojma@life.osaka-cu.ac.jp

Epidemiological and animal studies have indicated that consumption of green tea is associated with a reduced risk of developing certain forms of cancer. However, the inhibitory mechanism of green tea in angiogenesis, an important process in tumor growth, has not been well established. In the present study, green tea extract (GTE) was tested for its ability to inhibit cell viability, cell proliferation, cell cycle dynamics, vascular endothelial growth factor (VEGF) and expression of VEGF receptors fms-like tyrosine kinase (Flt-1) and fetal liver kinase-1/Kinase insert domain containing receptor (Flk-1/KDR) in vitro using human umbilical vein endothelial cells (HUVECs). GTE in culture media did not affect cell viability but significantly reduced cell proliferation dose-dependently and caused a dose-dependent accumulation of cells in the G1 phase. The decrease of the expression of Flt-1 and KDR/Flk-1 in HUVEC by GTE was detected with immunohistochemical and Western blotting methods. These results suggest that GTE may have preventive effects on tumor angiogenesis and metastasis through reduction of expression of VEGF receptors.

31. Int J Cancer. 2003 Sep 10;106(4):574-9.

Green tea and risk of breast cancer in Asian Americans.

Wu AH, Yu MC, Tseng CC, Hankin J, Pike MC.

Department of Preventive Medicine, University of Southern California, Keck School of Medicine, Los Angeles, CA, USA. annawu@hsc.usc.edu

There is substantial in vitro and in vivo evidence implicating tea polyphenols as chemopreventive agents against various cancers. However, epidemiologic data obtained from mainly Western populations are not supportive of a protective role of tea, mainly black tea, in the etiology of breast cancer. Much less is known about the relationship between green tea and breast cancer risk. During 1995-1998, we conducted a population-based, case-control study of breast cancer among Chinese, Japanese and Filipino women in Los Angeles County and successfully interviewed 501 breast cancer patients and 594 control subjects. Detailed information on menstrual and reproductive factors; dietary habits, including intake of black and green tea; and other lifestyle factors was collected. Risk of breast cancer was not related to black tea consumption. In contrast, green tea drinkers showed a significantly reduced risk of breast cancer, and this was maintained after adjusting for age, specific Asian ethnicity, birthplace, age at menarche, parity, menopausal status, use of menopausal hormones, body size and intake of total calories and black tea. Compared to women who did not drink green tea regularly (i.e., less than once a month), there was a significant trend of decreasing risk with increasing amount of green tea intake, adjusted odds ratios being 1.00, 0.71 (95% confidence interval [CI] 0.51-0.99) and 0.53 (95% CI 0.35-0.78), respectively, in association with no, 0-85.7 and >85.7 ml of green tea per day. The significant inverse association between risk of breast cancer and green tea intake remained after further adjustment for other potential confounders, including smoking; alcohol, coffee and black tea intake; family history of breast cancer; physical activity; and intake of soy and dark green vegetables. While both green tea and soy intake had significant, independent protective effects on breast cancer risk, the benefit of green tea was primarily observed among subjects who were low soy consumers. Similarly, the protective effect of soy was primarily observed among subjects who were nondrinkers of green tea. In summary, our results point to an important role of both green tea and soy intake in relation to breast cancer risk in Asian-American women. Copyright 2003 Wiley-Liss, Inc.

32. J Nutr. 2003 Jul;133(7 Suppl):2417S-2424S.

Molecular targets for green tea in prostate cancer prevention.

Adhami VM, Ahmad N, Mukhtar H.

Department of Dermatology, University of Wisconsin, Madison, WI 53706, USA.

Prostate cancer (PCa) is the most frequently diagnosed malignancy and the second leading cause of cancer-related deaths in American males. For these reasons, it is necessary to intensify our efforts for better understanding and development of novel treatment and chemopreventive approaches for this disease. In recent years, green tea has gained considerable attention as an agent that could reduce the risk of several cancer types. The cancer-chemopreventive effects of green tea appear to be mediated by the polyphenolic constituents present therein. Based on geographical observations that suggest that the incidence of PCa is lower in Japanese and Chinese populations that consume green tea on a regular basis, we hypothesized that green tea and/or its constituents could be effective for chemoprevention of PCa. To investigate this hypothesis, we initiated a program for the chemoprevention of PCa by green tea. In cell-culture systems that employ human PCa cells DU145 (androgen insensitive) and LNCaP (androgen sensitive), we found that the major polyphenolic constituent (-)-epigallocatechin-3-gallate (EGCG) of green tea induces 1) apoptosis, 2) cell-growth inhibition, and 3) cyclin kinase inhibitor WAF-1/p21-mediated cell-cycle dysregulation. More recently, using a cDNA microarray, we found that EGCG treatment of LNCaP cells results in 1) induction of genes that functionally exhibit growth-inhibitory effects, and 2) repression of genes that belong to the G-protein signaling network. In animal studies that employ a transgenic adenocarcinoma of the mouse prostate (TRAMP), which is a model that mimics progressive forms of human prostatic disease, we observed that oral infusion of a polyphenolic fraction isolated from green tea (GTP) at a human achievable dose (equivalent to 6 cups of green tea/d) significantly inhibits PCa development and metastasis. We extended these studies and more recently observed increased expression of genes related to angiogenesis such as vascular endothelial growth factor (VEGF) and those related to metastasis such as matrix metalloproteinases (MMP)-2 and MMP-9 in prostate cancer of TRAMP mice. Oral feeding of GTP as the sole source of drinking fluid to TRAMP mice results in significant inhibition of VEGF, MMP-2 and MMP-9. These data suggest that there are multiple targets for PCa chemoprevention by green tea and highlight the need for further studies to identify novel pathways that may be modulated by green tea or its polyphenolic constituents that could be further exploited for prevention and/or treatment of PCa.

33. FEBS Lett. 2003 Jul 10;546(2-3):265-70.

Complex effects of different green tea catechins on human platelets.

Lill G, Voit S, Schror K, Weber AA.

Institut fur Pharmakologie und Klinische Pharmakologie, Universitatsklinikum Dusseldorf, Moorenstr 5, D-40225 Dusseldorf, Germany.

Epigallocatechin gallate (EGCG), a major component of green tea, has been previously shown to inhibit platelet aggregation. The effects of other green tea catechins on platelet function are not known. Pre-incubation with EGCG concentration-dependently inhibited thrombin-induced aggregation and phosphorylation of p38 mitogen-activated protein kinase and extracellular signal-regulated kinases-1/2. In contrast EGCG stimulated tyrosine phosphorylation of platelet proteins, including Syk and SLP-76 but inhibited phosphorylation of focal adhesion kinase. Other catechins did not inhibit platelet aggregation. Interestingly, when EGCG was added to stirred platelets, a tyrosine kinase-dependent stimulation of platelet aggregation was observed. The two other catechins containing a galloyl group in the 3' position (catechin gallate, epicatechin gallate) also stimulated platelet aggregation, while catechins without a galloyl group (catechin, epicatechin) or the catechin with a galloyl group in the 2' position (epigallocatechin) did not.

34. Arch Intern Med. 2003 Jun 23;163(12):1448-53.

Cholesterol-lowering effect of a theaflavin-enriched green tea extract: a randomized controlled trial.

Maron DJ, Lu GP, Cai NS, Wu ZG, Li YH, Chen H, Zhu JQ, Jin XJ, Wouters BC, Zhao J. Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA. david.maron@vanderbilt.edu

BACKGROUND: Tea consumption has been associated with decreased cardiovascular risk, but potential mechanisms of benefit are ill-defined. While epidemiologic studies suggest that drinking multiple cups of tea per day lowers low-density lipoprotein cholesterol (LDL-C), previous trials of tea drinking and administration of green tea extract have failed to show any impact on lipids and lipoproteins in humans. Our objective was to study the impact of a theaflavin-enriched green tea extract on the lipids and lipoproteins of subjects with mild to moderate hypercholesterolemia. METHODS: Double-blind, randomized, placebo-controlled, parallel-group trial set in outpatient clinics in 6 urban hospitals in China. A total of 240 men and women 18 years or older on a low-fat diet with mild to moderate hypercholesterolemia were randomly assigned to receive a daily capsule containing theaflavin-enriched green tea extract (375 mg) or placebo for 12 weeks. Main outcome measures were mean percentage changes in total cholesterol, LDL-C, high-density lipoprotein cholesterol (HDL-C), and triglyceride levels compared with baseline. RESULTS: After 12 weeks, the mean +/- SEM changes from baseline in total cholesterol, LDL-C, HDL-C, and triglyceride levels were -11.3% +/- 0.9% (P =.01), -16.4% +/- 1.1% (P =.01), 2.3% +/- 2.1% (P =.27), and 2.6% +/- 3.5% (P =.47), respectively, in the tea extract group. The mean levels of total cholesterol, LDL-C, HDL-C, and triglycerides did not change significantly in the placebo group. No significant adverse events were observed. CONCLUSION: The theaflavin-enriched green tea extract we studied is an effective adjunct to a low-saturated-fat diet to reduce LDL-C in hypercholesterolemic adults and is well tolerated.

35. Anticancer Res. 2003 Mar-Apr;23(2B):1533-9.

Green tea polyphenol targets the mitochondria in tumor cells inducing caspase 3-dependent apoptosis.

Hsu S, Lewis J, Singh B, Schoenlein P, Osaki T, Athar M, Porter AG, Schuster G.

Department of Oral Biology and Maxillofacial Pathology, School of Dentistry, AD1443. Medical College of Georgia, Augusta, GA 30912-1126, USA. shsu@mail.mcg.edu

Induction of apoptosis by green tea polyphenols has been observed in various tumor cell systems, but whether green tea polyphenol-induced apoptosis requires caspase 3 for execution has not been confirmed. We previously reported that green tea polyphenol-induced apoptosis involved Apaf-1 accumulation and caspase 3 activation in the cytosol. In the current study, tumor cells either with deleted caspase 3 gene or expressing wild-type caspase 3 were treated with increasing concentrations of green tea polyphenol(s), followed by morphological analysis and caspase 3 activity assay. The caspase 3 null parental cell line was further examined in comparison with a well-characterized, caspase 3 wild type oral carcinoma cell line by MTT assay and BrdU incorporation assay. The results demonstrated that, while the mitochondrial function gradually declined to insignificant levels, caspase 3 null cells did not undergo apoptosis, which suggested that green tea polyphenol-induced apoptosis is a mitochondria-targeted, caspase 3-executed mechanism.

36. Zhonghua Liu Xing Bing Xue Za Zhi. 2003 Mar;24(3):192-5.

[A case-control study on drinking green tea and decreasing risk of cancers in the alimentary canal among cigarette smokers and alcohol drinkers]

[Article in Chinese]

Mu LN, Zhou XF, Ding BG, Wang RH, Zhang ZF, Chen CW, Wei GR, Zhou XM, Jiang QW, Yu SZ.

School of Public Health, Fudan University, Shanghai 200032, China.

OBJECTIVE: To explore the role of green tea in decreasing the risks of gastric cancer, liver cancer, esophageal cancer among alcohol drinkers or cigarette smokers. METHODS: A population based case-control study was conducted in Taixing, Jiangsu province. RESULTS: In Taixing city, identified cases of stomach, liver and esophageal cancers were chosen with informed consent. The numbers were 206, 204, 218 respectively. Controls were chosen from normal population having lived in the area for longer than 10 years, also with informed consent. Green tea drinking seemed to have decreased 81%, 78%, 39% risk for the development of gastric cancer, liver cancer and esophageal cancer among alcohol drinkers. It might also have decreased 16%, 43%, 31% on the risks of developing the three kinds of cancers among cigarette smokers. Interaction assessment showed that drinking green tea could significantly decrease the risk of gastric cancer and liver cancer among alcohol drinkers, with ORs of interaction item 0.23 (95% CI: 0.10 - 0.55) and 0.25 (95% CI: 0.11 - 0.57) respectively. CONCLUSION: Habit of drinking green tea seemed to have significant protective effects on the development of both gastric and liver cancer among alcohol drinkers while, green tea also having some protective effect on esophageal cancer among alcohol drinkers and on three kinds of cancers among cigarette smokers.

37. Arch Dermatol Res. 2003 Jul;295(3):112-6. Epub 2003 Jun 13.

Comparative effects of polyphenols from green tea (EGCG) and soybean (genistein) on VEGF and IL-8 release from normal human keratinocytes stimulated with the proinflammatory cytokine TNFalpha.

Trompezinski S, Denis A, Schmitt D, Viac J.

INSERM U 346, Clinique Dermatologique, Hopital E. Herriot, 69437 Lyon, France.

In skin inflammation, vascular endothelial growth factor (VEGF) and IL-8 play an important role and are produced by activated keratinocytes. Recently, some polyphenols have been reported to exhibit antiinflammatory and antiangiogenic properties. We therefore evaluated the effects of green tea, its major component epigallocatechin-3-gallate (EGCG) and an isoflavone derived from soybean (genistein) on the release of VEGF and IL-8 by activated normal human keratinocytes (NHK). NHK cultured in defined medium were stimulated for 48 h with the proinflammatory cytokine TNFalpha with the addition or not of different concentrations of polyphenols. Levels of VEGF and IL-8 were measured in cell supernatants by enzyme-linked immunosorbent assays. The different constituents tested inhibited keratinocyte proliferation without inducing apoptosis. They reduced in a dose-dependent manner the basal release and the upregulation of VEGF in NHK. Green tea and EGCG were also potent inhibitors of IL-8 release by TNFalpha-stimulated NHK, whereas genistein exerted only minor effects. These results underline the divergent pathways involved in the downregulation of VEGF and IL-8 by polyphenols in activated keratinocytes. They also suggest that polyphenols may contribute to moderate inflammatory processes in skin diseases associated with angiogenesis.

38. Carcinogenesis. 2003 Jun;24(6):1105-9. Epub 2003 Apr 24.

Prevention of dual promoting effects of pentachlorophenol, an environmental pollutant, on diethylnitrosamine-induced hepato- and cholangiocarcinogenesis in mice by green tea infusion.

Umemura T, Kai S, Hasegawa R, Kanki K, Kitamura Y, Nishikawa A, Hirose M.

Division of Pathology, National Institute of Health Sciences, 1-18-1, Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan. umemura@nihs.go.jp

In order to explore a possibility that the custom of drinking green tea infusion is efficacious for reducing the carcinogenic risk of environmental exposure to pentachlorophenol (PCP), we examined the effects in a hepato- and cholangiocarcinogenesis model in mice exposed to diethylnitrosamine (DEN). In the first experiment, groups of 15 male mice were initially treated with DEN at a dose of 20 p.p.m. in the drinking water for the first 8 weeks followed by a 4 week recovery interval by PCP at concentrations of 0 (basal diet), 300 or 600 p.p.m. in the diet for 23 weeks. Further groups of animals were treated with DEN and PCP in the same manner and received 2% green tea infusion (GT) instead of the drinking water from week 10 until death. PCP exposure at the high dose promoted DEN-induced hepatocarcinogenesis, and also caused progression of cystic hyperplasias of the intrahepatic bile ducts to cholangiocellular tumors. Co-administration of GT was able to prevent the increases of incidences and multiplicities of DEN-induced hepatocellular tumors and also arrest the progression of cholangiocellular tumors. In the second experiment, co-treatment with GT in the drinking water from 1 week before 300 or 600 p.p.m. PCP treatment in the diet to the end of the experiment at week 3 in B6C3F1 male mice suppressed increases of serum ALT activities, 8-oxodeoxyguanosine levels in liver DNA and bromodeoxyuridine labeling indices of hepatocytes and intrahepatic biliary epithelial cells induced by PCP. These findings suggest that regular intake of green tea may reduce the carcinogenic risk posed by an environmental pollutant, PCP, presumably due to effects on oxidative stress.

39. DNA Cell Biol. 2003 Mar;22(3):217-24.

A major constituent of green tea, EGCG, inhibits the growth of a human cervical cancer cell line, CaSki cells, through apoptosis, G(1) arrest, and regulation of gene expression.

Ahn WS, Huh SW, Bae SM, Lee IP, Lee JM, Namkoong SE, Kim CK, Sin JI.

Department of Obstetrics and Gynecology, College of Medicine, The Catholic University of Korea, Seoul, Korea.

A constituent of green tea, (-)-epigallocatechin-3-gallate (EGCG) has been known to possess antiproliferative properties. In this study, we investigated the anticancer effects of EGCG in human papillomavirus (HPV)-16 associated cervical cancer cell line, CaSki cells. The growth inhibitory mechanism(s) and regulation of gene expression by EGCG were also evaluated. EGCG showed growth inhibitory effects in CaSki cells in a dose-dependent fashion, with an inhibitory dose (ID)(50) of approximately 35 microM. When CaSki cells were further tested for EGCG-induced apoptosis, apoptotic cells were significantly observed after 24 h at 100 microM EGCG. In contrast, an insignificant induction of apoptotic cells was observed at 35 microM EGCG. However, cell cycles at the G1 phase were arrested at 35 microM EGCG, suggesting that cell cycle arrests might precede apoptosis. When CaSki cells were tested for their gene expression using 384 cDNA microarray, an alteration in the gene expression was observed by EGCG treatment. EGCG downregulated the expression of 16 genes over time more than twofold. In contrast, EGCG upregulated the expression of four genes more than twofold, suggesting a possible gene regulatory role of EGCG. This data supports that EGCG can inhibit cervical cancer cell growth through induction of apoptosis and cell cycle arrest as well as regulation of gene expression in vitro. Furthermore, in vivo antitumor effects of EGCG were also observed. Thus, EGCG likely provides an additional option for a new and potential drug approach for cervical cancer patients.

40. J Biochem (Tokyo). 2003 May;133(5):571-6.

Inhibitory effects of green tea catechins on the activity of human matrix metalloproteinase 7 (matrilysin).

Oneda H, Shiihara M, Inouye K.

Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.

Inhibitory effects of green tea catechins and their derivatives on the matrilysin-catalyzed hydrolysis of a synthetic substrate, (7-methoxycoumarin-4-yl)acetyl-L-Pro-L-Leu-Gly-L-Leu-[N(3)-(2,4-dinitrophenyl)-L -2,3-diamino-propionyl]-L-Ala-L-Arg-NH(2) [MOCAc-PLGL(Dpa)AR], were examined. The 10 catechins examined were classified into three groups according to their inhibition potency. Catechins with a galloyl group at the 3 position, including a major component of green tea catechin, (-)-epigallo-3-catechin gallate [(-)-EGCG], were the most potent inhibitors and inhibited matrilysin in a non-competitive manner with K(i) values of 0.47-1.65 micro M. The inhibitory potency of (-)-EGCG was not influenced by the presence of an inhibitor, ZnCl(2), suggesting that the inhibitions of matrilysin by (-)-EGCG and by ZnCl(2) might be independent of each other. The inhibitory effects of green tea catechins suggest that a high intake of green tea might be effective for the prevention of tumor metastasis and invasion in which matrilysin is concerned.

41. Nutrition. 2003 Jun;19(6):536-40.

Effect of green tea in the prevention and reversal of fasting-induced intestinal mucosal damage.

Asfar S, Abdeen S, Dashti H, Khoursheed M, Al-Sayer H, Mathew T, Al-Bader A.

Department of Surgery, Faculty of Medicine, Kuwait University, PO Box 24923, Safat 13110, Kuwait. sami@hsc.kuniv.edu.kw

OBJECTIVE: Epidemiologic studies have suggested that high consumption of green tea protects against the development of chronic active gastritis and decreases the risk of stomach cancer. The effect of green tea on the intestinal mucosa was not studied previously, so we examined the effects of green tea on the intestinal mucosa of fasting rats in a controlled experimental setting. METHODS: Two sets of experiments were performed. In the recovery set, rats were fasted for 3 d, after which they were allowed free access to water, black tea, green tea, or vitamin E for 7 d. On day 8, the animals were killed, and small bowels were removed for histologic examination. In the pretreatment set, rats were allowed a normal diet, but the water supply was replaced with green tea, black tea, or vitamin E for 14 d. They were subsequently fasted for 3 d. On day 4, the rats were killed, and small bowels were removed for histologic examination. RESULTS: In the recovery set, fasting for 3 d caused shortening of villi, atrophy, and fragmentation of mucosal villous architecture, with a significant (P < 0.0001) reduction in the length and surface area of the villi. Ingestion of green tea and, to a lesser extent, vitamin E for 7 d helped in the recovery of villi to normal. In the pretreatment set, drinking green tea, black tea, or vitamin E for 14 d before fasting protected intestinal mucosa from damage. CONCLUSION: The mucosal and villous atrophy induced by fasting was reverted to normal by the ingestion of green tea and, to a lesser extent, vitamin E. Black tea ingestion had no effect. In addition, ingestion of black tea, green tea, and vitamin E before fasting protected the intestinal mucosa against atrophy.

42. Carcinogenesis. 2003 May;24(5):927-36.

Treatment of green tea polyphenols in hydrophilic cream prevents UVB-induced oxidation of lipids and proteins, depletion of antioxidant enzymes and phosphorylation of MAPK proteins in SKH-1 hairless mouse skin.

Vayalil PK, Elmets CA, Katiyar SK.

Department of Dermatology, University of Alabama at Birmingham, 1670 University Blvd, Volker Hall 557, 35294, USA.

The use of botanical supplements has received immense interest in recent years to protect human skin from adverse biological effects of solar ultraviolet (UV) radiation. The polyphenols from green tea are one of them and have been shown to prevent photocarcinogenesis in animal models but their mechanism of photoprotection is not well understood. To determine the mechanism of photoprotection in in vivo mouse model, topical treatment of polyphenols from green tea (GTP) or its most chemopreventive constituent (-)-epigallocatechin-3-gallate (EGCG) (1 mg/cm(2) skin area) in hydrophilic ointment USP before single (180 mJ/cm(2)) or multiple UVB exposures (180 mJ/cm(2), daily for 10 days) resulted in significant prevention of UVB-induced depletion of antioxidant enzymes such as glutathione peroxidase (78-100%, P < 0.005-0.001), catalase (51-92%, P < 0.001) and glutathione level (87-100%, P < 0.005). Treatment of EGCG or GTP also inhibited UVB-induced oxidative stress when measured in terms of lipid peroxidation (76-95%, P < 0.001), and protein oxidation (67-75%, P > 0.001). Further, to delineate the inhibition of UVB-induced oxidative stress with cell signaling pathways, treatment of EGCG to mouse skin resulted in marked inhibition of a single UVB irradiation-induced phosphorylation of ERK1/2 (16-95%), JNK (46-100%) and p38 (100%) proteins of MAPK family in a time-dependent manner. Identical photoprotective effects of EGCG or GTP were also observed against multiple UVB irradiation-induced phosphorylation of the proteins of MAPK family in vivo mouse skin. Photoprotective efficacy of GTP given in drinking water (d.w.) (0.2%, w/v) was also determined and compared with that of topical treatment of EGCG and GTP. Treatment of GTP in d.w. also significantly prevented single or multiple UVB irradiation-induced depletion of antioxidant enzymes (44-61%, P < 0.01-0.001), oxidative stress (33-71%, P < 0.01) and phosphorylation of ERK1/2, JNK and p38 proteins of MAPK family but the photoprotective efficacy was comparatively less than that of topical treatments of EGCG and GTP. Lesser photoprotective efficacy of GTP in d.w. in comparison with topical application may be due to its less bioavailability in skin target cells. Together, for the first time a cream based formulation of green tea polyphenols was tested in this study to explore the possibility of its use for the humans, and the data obtained from this in vivo study further suggest that GTP could be useful in attenuation of solar UVB light-induced oxidative stress-mediated and MAPK-caused skin disorders in humans.

43. Exp Mol Med. 2003 Apr 30;35(2):136-9.

Epigallocatechin gallate, a constituent of green tea, suppresses cytokine-induced pancreatic beta-cell damage.

Han MK.

Department of Microbiology, Chonbuk National University Medical School and Institute for Medical Sciences, Jeonju 560-756, Korea.

Cytokines produced by immune cells infiltrating pancreatic islets have been implicated as one of the important mediators of beta-cell destruction in insulin-dependent diabetes mellitus. In this study, the protective effects of epigallocatechin gallate (EGCG) on cytokine-induced beta-cell destruction were investigated. EGCG effectively protected IL-1beta and IFN-gamma-mediated cytotoxicity in insulinoma cell line (RINm5F). EGCG induced a significant reduction in IL-1beta and IFN-gamma-induced nitric oxide (NO) production and reduced levels of the inducible form of NO synthase (iNOS) mRNA and protein levels on RINm5F cells. The molecular mechanism by which EGCG inhibited iNOS gene expression appeared to involve the inhibition of NF-kappaB activation. These findings revealed EGCG as a possible therapeutic agent for the prevention of diabetes mellitus progression.

44. Oral Microbiol Immunol. 2003 Jun;18(3):192-5.

Inhibitory effects of green tea catechins on protein tyrosine phosphatase in Prevotella intermedia.

Okamoto M, Leung KP, Ansai T, Sugimoto A, Maeda N.

Department of Oral Bacteriology, Tsurumi University School of Dental Medicine, Yokohama, Japan.

Members of the Prevotella intermedia group possess protein tyrosine phosphatase (PTPase). The purpose of this study was to investigate the effects of catechin derivatives from Japanese green tea on the activity of PTPase in P. intermedia and related organisms. Multilocus enzyme electrophoresis of alkaline phosphatase derived from P. intermedia, Prevotella nigrescens, Prevotella pallens and Porphyromonas gingivalis revealed a species-specific migration pattern. Among the tea catechin derivatives tested, (-)-epigallocatechin gallate (EGCg), similar to orthovanadate, a specific inhibitor for PTPase, was effective in inhibiting the PTPase activity in P. intermedia at 0.5 microm, and related species at 5 microm. The results suggested that the inhibitory effect observed is due to the presence of galloyl moiety in the structure. In contrast, neither the green tea catechins nor orthovanadate inhibited the phosphatase activity in P. gingivalis, suggesting that this organism possessed a different family of alkaline phosphatase.

45. Phytother Res. 2003 May;17(5):566-7.

Superoxide dismutase activity enhanced by green tea inhibits lipid accumulation in 3T3-L1 cells.

Mori M, Hasegawa N.

Department of Food and Nutrition, Nagoya Bunri College, Nagoya, Japan.

We studied the effect of powdered green tea on intracellular superoxide dismutase activity in the adipose conversion of 3T3-L1 cells. By the 14 days of culture with insulin, the triglyceride concentration was increased. When powdered green tea and insulin were added simultaneously, the increased triglyceride content was decreased (p < 0.05), and the superoxide dismutase activities were significantly enhanced (p < 0.05). These data suggest that green tea may have an antilipogenic activity due to its radical scavenging activity mechanism. Copyright 2003 John Wiley & Sons, Ltd.

46. Phytother Res. 2003 May;17(5):477-80.

Powdered green tea has antilipogenic effect on Zucker rats fed a high-fat diet.

Hasegawa N, Yamda N, Mori M.

Department of Food and Nutrition, Nagoya Bunri College, Nagoya, Japan. hsgwn@nagoya-bunri.ac.jp

The effect of powdered green tea on the lipid metabolism was studied in male Zucker rats fed a 50% sucrose diet containing 15% butter. The oral treatment of 130 mg powdered green tea per day depressed body weight increase and various adipose tissue weights but food intake was unaffected. The treatment also slightly increased the plasma triglycerides. These effects were likely mediated by the inhibition of lipogenesis in the adipose tissues. The experimental group had a higher concentration of liver total lipid, triglycerides and plasma protein, and lower liver weights than the controls. This may be due to lipid deposition in the liver because of the reduction in adipose tissue weights. It was found that powdered green tea lowered the plasma total cholesterol but liver total cholesterol was unaffected. The results indicate that the hypocholesterolemic activity of powdered green tea might be due to the inhibition of the synthesis of cholesterol in the liver. Copyright 2003 John Wiley & Sons, Ltd.

47. J Agric Food Chem. 2003 May 21;51(11):3379-81.

Effect of selenium on the yield and quality of green tea leaves harvested in early spring.

Hu Q, Xu J, Pang G.

Laboratory of Food Processing and Quality Control, College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, People's Republic of China.

Foliar applications of a fertilizer of selenite or selenate were carried out to determine the influence of selenium on the yield and quality of green tea leaves harvested in early spring. Numbers of sprouts and the yield were significantly increased by the application of selenium. The sweetness and aroma of green tea leaves were also significantly enhanced, and bitterness was significantly decreased by the application of selenium. However, no significant differences were found in sweetness, bitterness, and aroma between tea leaves fertilized with selenite and selenate. Se concentration was significantly increased by selenium fertilization, and tea enriched by sodium selenate had a significantly higher selenium content than did tea enriched by sodium selenite. Total amino acid and vitamin C contents were significantly enhanced by the application of selenium. Tea polyphenol contents were significantly decreased by fertilization with selenium. The marked difference of tea polyphenols was also found between applications of selenite and selenate.

48. Antiviral Res. 2003 Apr;58(2):167-73.

Inhibition of adenovirus infection and adenain by green tea catechins.

Weber JM, Ruzindana-Umunyana A, Imbeault L, Sircar S.

Departement de Microbiologie et d'Infectiologie, Faculte de Medecine, Universite de Sherbrooke, Que, Sherbrooke, Canada J1H 5N4. joseph.weber@usherbrooke.ca

Green tea catechins have been reported to inhibit proteases involved in cancer metastasis and infection by influenza virus and HIV. To date there are no effective anti-adenoviral therapies. Consequently, we studied the effect of green tea catechins, and particularly the predominant component, epigallocatechin-3-gallate (EGCG), on adenovirus infection and the viral protease adenain, in cell culture. Adding EGCG (100 microM) to the medium of infected cells reduced virus yield by two orders of magnitude, giving and IC(50) of 25 microM and a therapeutic index of 22 in Hep2 cells. The agent was the most effective when added to the cells during the transition from the early to the late phase of viral infection suggesting that EGCG inhibits one or more late steps in virus infection. One of these steps appears to be virus assembly because the titer of infectious virus and the production of physical particles was much more affected than the synthesis of virus proteins. Another step might be the maturation cleavages carried out by adenain. Of the four catechins tested on adenain, EGCG was the most inhibitory with an IC(50) of 109 microM, compared with an IC(50) of 714 microM for PCMB, a standard cysteine protease inhibitor. EGCG and different green teas inactivated purified adenovirions with IC(50) of 250 and 245-3095, respectively. We conclude that the anti-adenoviral activity of EGCG manifests itself through several mechanisms, both outside and inside the cell, but at effective drug concentrations well above that reported in the serum of green tea drinkers.

49. Arch Pharm Res. 2003 Mar;26(3):214-23.

Comparison of green tea extract and epigallocatechin gallate on blood pressure and contractile responses of vascular smooth muscle of rats.

Lim DY, Lee ES, Park HG, Kim BC, Hong SP, Lee EB.

Department of Pharmacology, College of Medicine, Chosun University, Gwangju 501-759, Korea. dylim@chosun.ac.kr

The present study was conducted to investigate the effects of green tea extract (GTE) on arteral blood pressure and contractile responses of isolated aortic strips of the normotensive rats and to establish the mechanism of action. The phenylephrine (10(-8) approximately 10(-5) M)-induced contractile responses were greatly inhibited in the presence of GTE (0.3 approximately 1.2 mg/mL) in a dose-dependent fashion. Also, high potassium (3.5 x 10(-2) approximately 5.6 x 10(-2) M)-induced contractile responses were depressed in the presence of 0.6 approximately 1.2 mg/mL of GTE, but not affected in low concentration of GTE (0.3 mg/mL). However, epigallocatechin gallate (EGCG, 4 approximately 12 microg/mL) did not affect the contractile responses evoked by phenylephrine and high K+. GTE (5 approximately 20 mg/kg) given into a femoral vein of the normotensive rat produced a dose-dependent depressor response, which is transient. Interestingly, the infusion of a moderate dose of GTE (10 mg/kg/30 min) made a significant reduction in pressor responses induced by intravenous norepinephrine. However, EGCG (1 mg/kg/30 min) did not affect them. Collectively, these results obtained from the present study demonstrate that intravenous GTE causes a dose-dependent depressor action in the anesthetized rat at least partly through the blockade of adrenergic alpha1-receptors. GTE also causes the relaxation in the isolated aortic strips of the rat via the blockade of adrenergic alpha1-receptors, in addition to the unknown direct mechanism. It seems that there is a big difference in the vascular effect between GTE and EGCG.

50. Phytother Res. 2003 Apr;17(4):358-63.

DNA degradation by water extract of green tea in the presence of copper ions: implications for anticancer properties.

Malik A, Azam S, Hadi N, Hadi SM.

Department of Biochemistry, Faculty of Life Science, AMU, Aligarh, India.

In recent years a number of reports have documented the chemopreventive effect of green tea consumption on various types of cancers such as those of bladder, prostate, esophagus and stomach. This property is attributed to the presence in green tea of polyphenols known as catechins. These include epigallocatechin-3-gallate, epigallocatechin and epicatechin. In addition to their antioxidant properties plant derived polyphenolics are also capable of oxidative DNA damage particularly in the presence of transition metal ions. We have recently proposed a mechanism for cytotoxic action of plant-derived polyphenols against cancer cells that involves mobilization of endogenous copper and consequent prooxidant action. In partial support of the idea, in the present paper we show that water extract of green tea is considerably more efficient than black tea extract in DNA cleavage in the presence of copper ions. Green tea extract also shows a higher rate of Cu(II) reduction and consequent hydroxyl radical formation. Cu(II) reduction is presumably accompanied by the formation of 'oxidized species' of tea polyphenols, which in turn also appear to catalyze the reduction of Cu(II) leading to redox cycling of copper ions. The results are discussed in relation to the structural differences between polyphenols of green and black tea. Copyright 2003 John Wiley & Sons, Ltd.

51. Thromb Haemost. 2003 May;89(5):866-74.

Green tea epigallocatechin-3-gallate inhibits platelet signalling pathways triggered by both proteolytic and non-proteolytic agonists.

Deana R, Turetta L, Donella-Deana A, Dona M, Maria Brunati A, De Michiel L, Garbisa S.

Department of Biological Chemistry and Institute of the Neuroscience of the Italian National Research Council (CNR), University of Padova, Italy, E-mail: arianna.donella@unipd.it

Epigallocatechin-3-gallate (EGCG), a component of green tea, inhibits human platelet aggregation and cytosolic [Ca(2+)](c) increases more strongly when these processes are induced by thrombin than by the non-proteolytic thrombin receptor activating peptide (TRAP), thromboxane mimetic U46619, or fluoroaluminate. In line with the previously demonstrated EGCG anti-proteolytic activity, a marked inhibition on aggregation is obtained by pre-incubation of thrombin with EGCG prior to addition to cellular suspension. The catechin also reduces cellular Ca(2+) influx following thapsigargin-induced calcium emptying of endoplasmic reticulum, and the agonist-promoted cellular protein tyrosine phosphorylation. Both tyrosine kinases Syk and Lyn, immuno-precipitated from stimulated platelets, are greatly inhibited upon cellular pre-incubation with EGCG, which also inhibits the in vitro auto-phosphorylation and exogenous activity of these two enzymes purified from rat spleen. Both thrombin-induced aggregation and [Ca(2+)](c) increase are reduced in platelets from rats that drank green tea solutions. It is concluded that EGCG inhibits platelet activation, by hindering the thrombin proteolytic activity, and by reducing the agonist-induced [Ca(2+)](c) increase through inhibition of Syk and Lyn activities.

52. J Immunol. 2003 Apr 15;170(8):4335-41.

Neutrophil restraint by green tea: inhibition of inflammation, associated angiogenesis, and pulmonary fibrosis.

Dona M, Dell'Aica I, Calabrese F, Benelli R, Morini M, Albini A, Garbisa S.

Department of Experimental Biomedical Sciences, Medical School of Padova, Padova, Italy.

Neutrophils play an essential role in host defense and inflammation, but the latter may trigger and sustain the pathogenesis of a range of acute and chronic diseases. Green tea has been claimed to exert anti-inflammatory properties through unknown molecular mechanisms. We have previously shown that the most abundant catechin of green tea, (-)epigallocatechin-3-gallate (EGCG), strongly inhibits neutrophil elastase. Here we show that 1) micromolar EGCG represses reactive oxygen species activity and inhibits apoptosis of activated neutrophils, and 2) dramatically inhibits chemokine-induced neutrophil chemotaxis in vitro; 3) both oral EGCG and green tea extract block neutrophil-mediated angiogenesis in vivo in an inflammatory angiogenesis model, and 4) oral administration of green tea extract enhances resolution in a pulmonary inflammation model, significantly reducing consequent fibrosis. These results provide molecular and cellular insights into the claimed beneficial properties of green tea and indicate that EGCG is a potent anti-inflammatory compound with therapeutic potential.

53. Curr Med Chem Anti-Canc Agents. 2002 Jul;2(4):441-63.

Green tea catechins as novel antitumor and antiangiogenic compounds.

Demeule M, Michaud-Levesque J, Annabi B, Gingras D, Boivin D, Jodoin J, Lamy S, Bertrand Y, Beliveau R.

Laboratoire de Medecine Moleculaire, UQAM-Hocric;pital Sainte-Justine, Montreal, Canada.

The concept of cancer prevention by use of naturally occuring substances that could be included in the diet is under investigation as a practical approach towards reducing cancer incidence, and therefore the mortality and morbidity associated with this disease. Tea, which is the most popularly consumed beverage aside from water, has been particularly associated with decreased risk of various proliferative diseases such as cancer and atherosclerosis in humans. Various studies have provided evidence that polyphenols are the strongest biologically active agents in green tea. Green tea polyphenols (GTPs) mainly consist of catechins (3-flavanols), of which (-)-epigallocatechin gallate is the most abundant and the most extensively studied. Recent observations have raised the possibility that green tea catechins, in addition to their antioxidative properties, also affect the molecular mechanisms involved in angiogenesis, extracellular matrix degradation, regulation of cell death and multidrug resistance. This article will review the effects and the biological activities of green tea catechins in relation to these mechanisms, each of which plays a crucial role in the development of cancer in humans. The extraction of polyphenols from green tea, as well as their bioavailability, are also discussed since these two important parameters affect blood and tissue levels of the GTPs and consequently their biological activities. In addition, general perspectives on the application of dietary GTPs as novel antiangiogenic and antitumor compounds are also presented.

54. Kidney Int. 2003 May;63(5):1785-90.

Effect of green tea extract on cardiac hypertrophy following 5/6 nephrectomy in the rat.

Priyadarshi S, Valentine B, Han C, Fedorova OV, Bagrov AY, Liu J, Periyasamy SM, Kennedy D, Malhotra D, Xie Z, Shapiro JI.

The Department of Medicine, Medical College of Ohio, Toledo, Ohio 43614, USA.

BACKGROUND: Left ventricular hypertrophy commonly complicates chronic renal failure. We have observed that at least one pathway of left ventricular hypertrophy appears to involve signaling through reactive oxygen species (ROS). Green tea is a substance that appears to have substantial antioxidant activity, yet is safe and is currently widely used. We, therefore, studied whether green tea supplementation could attenuate the development of left ventricular hypertrophy in an animal model of chronic renal failure. METHODS: Male Sprague-Dawley rats were subjected to sham or remnant kidney surgery and given green tea extract (0.1% and 0.25%) or plain drinking water for the next 4 weeks. Heart weight, body weight, and cardiac Na-K-ATPase activity were measured at the end of this period. To further test our hypothesis, we performed studies in cardiac myocytes isolated from adult male Sprague-Dawley rats. We measured the generation of ROS using the oxidant sensitive dye dichlorofluorescein (DCF) as well as (3H)phenylalanine incorporation following exposure to cardiac glycosides with and without green tea extract. RESULTS: Administration of green tea extract at 0.25% resulted in attenuation of left ventricular hypertrophy, hypertension, and preserved cardiac Na-K-ATPase activity in rats subjected to remnant kidney surgery (all P < 0.01). In subsequent studies performed in isolated cardiac myocytes, both ouabain and marinobufagenin (MBG) were both found to increase ROS production and (3H)phenylalanine incorporation at concentrations substantially below their inhibitor concentration (IC) 50 for the sodium pump. Addition of green tea extract prevented increases in ROS production as well as (3H)phenylalanine incorporation in these isolated cardiac myocytes. CONCLUSION: Green tea extract appears to block the development of cardiac hypertrophy in experimental renal failure. Some of this effect may be related to the attenuation of hypertension, but a direct effect on cardiac myocyte ROS production and growth was also identified. Clinical studies of green tea extract in chronic renal failure patients may be warranted.

55. Phytother Res. 2003 Mar;17(3):206-9.

Protective effect of green tea polyphenol (-)-epigallocatechin gallate and other antioxidants on lipid peroxidation in gerbil brain homogenates.

Lee SR, Im KJ, Suh SI, Jung JG.

Department of Pharmacology, School of Medicine and Brain Research Institute, Keimyung University, Taegu, South Korea. srlee@dsmc.or.kr

The aim of this study was to compare the protective effects of green tea polyphenol (-)-epigallocatechin gallate (EGCG) and other well-known antioxidants on the lipid peroxidation in gerbil brain homogenates. Oxidative stress was induced by H2O2 (10 mM) or ferrous ammonium sulfate (5 microM) and lipid peroxidation was studied. Hydrogen peroxide and ferrous ions are capable of oxidizing a wide range of substrates and causing biological damage. The reaction, referred to as the Fenton process, is complex and can generate both hydroxyl radicals and higher oxidation states of the iron. Thiobarbituric acid-reactive substances (TBA-RS) were used as a marker of lipid peroxidation. EGCG, trolox, lipoic acid, and melatonin reduced H2O2- or ferrous ion-induced lipid peroxidation in a concentration-dependent manner. In reducing the H2O2-induced lipid peroxidation, IC50 values of antioxidants were as follows: EGCG (0.66 microM), trolox (37.08 microM), lipoic acid (7.88 mM), and melatonin (19.11 mM). In reducing the ferrous ion-induced lipid peroxidation, IC50 values of antioxidants were as follows: EGCG (3.32 microM), trolox (75.65 microM), lipoic acid (7.63 mM), and melatonin (15.48 mM). Under the in vitro conditions of this experiment, EGCG was the most potent antioxidant in inhibiting H2O2 or ferrous ion-induced lipid peroxidation in the gerbil brain homogenates. Copyright 2003 John Wiley & Sons, Ltd.

56. FASEB J. 2003 May;17(8):952-4. Epub 2003 Mar 28.

Neuroprotection and neurorescue against Abeta toxicity and PKC-dependent release of nonamyloidogenic soluble precursor protein by green tea polyphenol (-)-epigallocatechin-3-gallate.

Levites Y, Amit T, Mandel S, Youdim MB.

Eve Topf and USA National Parkinson Foundation, Centers of Excellence for Neurodegenerative Diseases Research, Technion Faculty of Medicine, Haifa, Israel.

Green tea extract and its main polyphenol constituent (-)-epigallocatechin-3-gallate (EGCG) possess potent neuroprotective activity in cell culture and mice model of Parkinson's disease. The central hypothesis guiding this study is that EGCG may play an important role in amyloid precursor protein (APP) secretion and protection against toxicity induced by beta-amyloid (Abeta). The present study shows that EGCG enhances (approximately 6-fold) the release of the non-amyloidogenic soluble form of the amyloid precursor protein (sAPPalpha) into the conditioned media of human SH-SY5Y neuroblastoma and rat pheochromocytoma PC12 cells. sAPPalpha release was blocked by the hydroxamic acid-based metalloprotease inhibitor Ro31-9790, which indicated mediation via alpha-secretase activity. Inhibition of protein kinase C (PKC) with the inhibitor GF109203X, or by down-regulation of PKC, blocked the EGCG-induced sAPPalpha secretion, suggesting the involvement of PKC. Indeed, EGCG induced the phosphorylation of PKC, thus identifying a novel PKC-dependent mechanism of EGCG action by activation of the non-amyloidogenic pathway. EGCG is not only able to protect, but it can rescue PC12 cells against the beta-amyloid (Abeta) toxicity in a dose-dependent manner. In addition, administration of EGCG (2 mg/kg) to mice for 7 or 14 days significantly decreased membrane-bound holoprotein APP levels, with a concomitant increase in sAPPalpha levels in the hippocampus. Consistently, EGCG markedly increased PKCalpha and PKC in the membrane and the cytosolic fractions of mice hippocampus. Thus, EGCG has protective effects against Abeta-induced neurotoxicity and regulates secretory processing of non-amyloidogenic APP via PKC pathway.

57. J Agric Food Chem. 2003 Apr 9;51(8):2421-5.

Influence of green tea polyphenol in rats with arginine-induced renal failure.

Yokozawa T, Cho EJ, Nakagawa T.

Institute of Natural Medicine, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama 930-0194, Japan. yokozawa@ms.toyama-mpu.ac.jp

To determine whether green tea polyphenol ameliorates the pathological conditions induced by excessive dietary arginine, green tea polyphenol was administered to rats at a daily dose of 50 or 100 mg/kg body weight for 30 days with a 2% w/w arginine diet. In arginine-fed control rats, urinary and/or serum levels of guanidino compounds, nitric oxide (NO), urea, protein, and glucose increased significantly, while the renal activities of the oxygen species-scavenging enzymes superoxide dismutase (SOD) and catalase decreased, compared with casein-fed rats. However, rats given green tea polyphenol showed significant and dose-dependent decreases in serum levels of creatinine (Cr) and urea nitrogen and urinary excretion of Cr, and they exerted a slight reduction of nitrite plus nitrate, indicating that green tea polyphenol reduced the production of uremic toxins and NO. In addition, in arginine-fed rats the urinary urea, protein, and glucose level increases were reversed by the administration of green tea polyphenol. Moreover, in rats given green tea polyphenol the SOD and catalase activities suppressed by excessive arginine administration increased dose-dependently, implying the biological defense system was augmented as a result of free radical scavenging. These results suggest that green tea polyphenol would ameliorate renal failure induced by excessive dietary arginine by decreasing uremic toxin, and NO production and increasing radical-scavenging enzyme activity.

58. J Pharmacol Exp Ther. 2003 Jul;306(1):29-34. Epub 2003 Mar 27.

Green tea polyphenols induce differentiation and proliferation in epidermal keratinocytes.

Hsu S, Bollag WB, Lewis J, Huang Q, Singh B, Sharawy M, Yamamoto T, Schuster G.

Department of Oral Biology and Maxillofacial Pathology, School of Dentistry, AD1443. Medical College of Georgia, Augusta, GA 30912-1126, USA. shsu@mail.mcg.edu

The most abundant green tea polyphenol, epigallocatechin-3-gallate (EGCG), was found to induce differential effects between tumor cells and normal cells. Nevertheless, how normal epithelial cells respond to the polyphenol at concentrations for which tumor cells undergo apoptosis is undefined. The current study tested exponentially growing and aged primary human epidermal keratinocytes in response to EGCG or a mixture of the four major green tea polyphenols. EGCG elicited cell differentiation with associated induction of p57/KIP2 within 24 h in growing keratinocytes, measured by the expression of keratin 1, filaggrin, and transglutaminase activity. Aged keratinocytes, which exhibited low basal cellular activities after culturing in growth medium for up to 25 days, renewed DNA synthesis and activated succinate dehydrogenase up to 37-fold upon exposure to either EGCG or the polyphenols. These results suggest that tea polyphenols may be used for treatment of wounds or certain skin conditions characterized by altered cellular activities or metabolism.

59. Mutat Res. 2003 Feb-Mar;523-524:33-41.

Anticlastogenic, antigenotoxic and apoptotic activity of epigallocatechin gallate: a green tea polyphenol.

Roy M, Chakrabarty S, Sinha D, Bhattacharya RK, Siddiqi M.

Department of Environmental Carcinogenesis and Toxicology, Chittaranjan National Cancer Institute, 37 SP Mukherjee Road, Kolkata 700 026, India.

Modulation of events characteristic of carcinogenesis or of cancer cells is being emphasized as a rational strategy to control cancer. Green tea polyphenol epigallocatechin gallate (EGCG) has been shown to be highly active as a cancer chemopreventive agent. Certain cellular and molecular events relevant to carcinogenesis are also modified by EGCG. The present investigation was carried out to examine the effects of EGCG on the cytogenetic change and DNA damage induced by toxicant H(2)O(2) and carcinogen N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in Chinese hamster V-79 cells in culture. Cytogenetic change as evident by the formation of micronuclei and DNA damage in the form of comet tail length during single cell gel electrophoresis was found to be significantly suppressed by EGCG in a dose dependent manner. Cells preincubated with EGCG were protected from subsequent damage by the genotoxic agents. Apoptosis, a highly organized physiological mechanism to eliminate injured or abnormal cells, is also implicated in multistage carcinogenesis. Initiated cells, cells at promotional stage or fully transformed cells can be eliminated through apoptosis. It was observed that EGCG suppressed growth and proliferation of K-562 cells derived from human chronic myelogenic leukemia. Morphological features of treated cells and characteristic DNA fragmentation revealed that the cytotoxicity was due to induction of apoptosis. This was mediated by activation of caspase 3 and caspase 8. Results show that EGCG not only protects normal cells against genotoxic hazard but also eliminate cancer cells through induction of apoptosis. Copyright 2002 Elsevier Science B.V.

60. Cancer. 2003 Mar 15;97(6):1442-6.

A phase II trial of green tea in the treatment of patients with androgen independent metastatic prostate carcinoma.

Jatoi A, Ellison N, Burch PA, Sloan JA, Dakhil SR, Novotny P, Tan W, Fitch TR, Rowland KM, Young CY, Flynn PJ.

Mayo Clinic and Mayo Foundation, Rochester, Minnesota 55905, USA. jatoi.aminah@mayo.edu

BACKGROUND: Recent laboratory and epidemiologic studies have suggested that green tea has antitumor effects in patients with prostate carcinoma. This Phase II trial explored green tea's antineoplastic effects in patients with androgen independent prostate carcinoma. METHODS: This study, which was conducted by the North Central Cancer Treatment Group, evaluated 42 patients who were asymptomatic and had manifested, progressive prostate specific antigen (PSA) elevation with hormone therapy. Continued use of luteinizing hormone-releasing hormone agonist was permitted; however, patients were ineligible if they had received other treatments for their disease in the preceding 4 weeks or if they had received a long-acting antiandrogen therapy in the preceding 6 weeks. Patients were instructed to take 6 grams of green tea per day orally in 6 divided doses. Each dose contained 100 calories and 46 mg of caffeine. Patients were monitored monthly for response and toxicity. RESULTS: Tumor response, defined as a decline >/= 50% in the baseline PSA value, occurred in a single patient, or 2% of the cohort (95% confidence interval, 1-14%). This one response was not sustained beyond 2 months. At the end of the first month, the median change in the PSA value from baseline for the cohort increased by 43%. Green tea toxicity, usually Grade 1 or 2, occurred in 69% of patients and included nausea, emesis, insomnia, fatigue, diarrhea, abdominal pain, and confusion. However, six episodes of Grade 3 toxicity and one episode of Grade 4 toxicity also occurred, with the latter manifesting as severe confusion. CONCLUSIONS: Green tea carries limited antineoplastic activity, as defined by a decline in PSA levels, among patients with androgen independent prostate carcinoma. Copyright 2003 American Cancer Society.DOI 10.1002/cncr.11200

61. Int J Urol. 2003 Mar;10(3):160-6.

Preventive effects of urinary bladder tumors induced by N-butyl-N-(4-hydroxybutyl)-nitrosamine in rat by green tea leaves.

Sato D, Matsushima M.

Second Department of Urology, Toho University of Medicine, Tokyo, Japan. sai2uro@oha.toho-u.ac.jp

BACKGROUND: Recently, the anticarcinogenic effects of green tea have been studied in sites other than the urinary tract. Although the incidence of bladder cancer has increased, responses to therapy have been limited. The present work examined the preventive effects of green tea against bladder tumors induced in rats by the carcinogen, N-butyl-N-(4-hydroxybutyl)-nitrosamine(BBN). METHODS: From week 5 to week 9, all the groups were exposed to 0.05% BBN in the drinking water for 5 weeks. Rats were divided into four groups. Group 1 was fed a CE-2 diet and tap water for the entire experimental period and served as the control group. Group 2 was fed the green tea leaves after carcinogen exposure. Groups 3 and 4 received green tea leaves before carcinogen exposure. All rats were killed and examined at 44 weeks. RESULTS: Green tea leaves prevented the growth of BBN-induced urinary bladder tumors when given before the carcinogen. CONCLUSION: Green tea may inhibit tumor initiation in the bladder.

62. J Biomed Sci. 2003 Mar-Apr;10(2):219-27.

Green Tea Constituent (-)-Epigallocatechin-3-Gallate Inhibits Hep G2 Cell Proliferation and Induces Apoptosis through p53-Dependent and Fas-Mediated Pathways.

Kuo PL, Lin CC.

Graduate Institute of Natural Products, Kaohsiung Medical University, Kaohsiung, Taiwan, ROC.

(-)-Epigallocatechin-3-gallate (EGCG) is a polyphenolic compound found in green tea. It has been reported to possess a wide range of pharmacological properties, and is one of the most promising chemopreventive agents for cancer. To provide a better understanding of the preventive effect of EGCG on liver cancer, we examined EGCG for its effect on proliferation and cell cycle progression in a human liver cancer cell line, Hep G2. The results showed that EGCG inhibited the proliferation of Hep G2 by inducing apoptosis and blocking cell cycle progression in the G1 phase. ELISA showed that EGCG significantly increased the expression of p53 and p21/WAF1 protein, and this contributed to cell cycle arrest. An enhancement in Fas/APO-1 and its two form ligands, membrane-bound Fas ligand (mFasL) and soluble Fas ligand (sFasL), as well as Bax protein, was responsible for the apoptotic effect induced by EGCG. Taken together, our study suggests that the induction of p53 and the activity of the Fas/FasL apoptotic system play major roles in the antiproliferative activity of EGCG in Hep G2 cells. Copyright 2003 National Science Council, ROC and S. Karger AG, Basel

63. Oncogene. 2003 Feb 20;22(7):1035-44.

Inhibition of ultraviolet B-mediated activation of nuclear factor kappaB in normal human epidermal keratinocytes by green tea Constituent (-)-epigallocatechin-3-gallate.

Afaq F, Adhami VM, Ahmad N, Mukhtar H.

Department of Dermatology, University of Wisconsin, Madison, WI 53706, USA.

Epigallocatechin-3-gallate (EGCG), the major constituent of green tea, possesses significant anti-inflammatory and cancer chemopreventive properties. Studies have shown the photochemopreventive effects of green tea and EGCG in cell culture, animal models, and human skin. The molecular mechanism(s) of photochemopreventive effects of EGCG are incompletely understood. We recently showed that EGCG treatment of the normal human epidermal keratinocytes (NHEK) inhibits ultraviolet (UV)B-mediated activation of the mitogen-activated protein kinase (MAPK) pathway. In this study, we evaluated the effect of EGCG on UVB-mediated modulation of the nuclear factor kappa B (NF-kappaB) pathway, which is known to play a critical role in a variety of physiological functions and is involved in inflammation and development of cancer. Immunoblot analysis demonstrated that the treatment of NHEK with EGCG (10-40 microM) for 24 h resulted in a significant inhibition of UVB (40 mJ/cm(2))-mediated degradation and phosphorylation of IkappaBalpha and activation of IKKalpha, in a dose-dependent manner. UVB-mediated degradation and phosphorylation of IkappaBalpha and activation of IKKalpha was also observed in a time-dependent protocol (15 and 30 min, 1, 2, 3, 6, 12 h post-UVB exposure). Employing immunoblot analysis, enzyme-linked immunosorbent assay, and gel shift assay, we demonstrate that EGCG treatment of the cells resulted in a significant dose- and time-dependent inhibition of UVB-mediated activation and nuclear translocation of a NF-kappaB/p65. Our data suggest that EGCG protects against the adverse effects of UV radiation via modulations in NF-kappaB pathway, and provide a molecular basis for the photochemopreventive effect of EGCG.

64. FASEB J. 2003 Apr;17(6):702-4. Epub 2003 Feb 05.

Green tea polyphenol epigallocatechin-3 gallate induces apoptosis of proliferating vascular smooth muscle cells via activation of p53.

Hofmann CS, Sonenshein GE.

Department of Biochemistry, Boston University School of Medicine, Massachusetts 02118, USA.

Green tea polyphenols (GTPs), which possess antioxidant properties, have been shown to inhibit the development of atherosclerotic lesions. Epigallocatechin-3-gallate (EGCG), the most abundant GTP, displays antiproliferative effects in a variety of cell types. Here, we examined the effects of GTPs on aortic smooth muscle cell (SMC) proliferation. Treatment with a GTP mixture or EGCG at a dose of 40 to 50 microg/ml slowed SMC growth, while at a higher dose of 80 microg/ml EGCG also induced cell death as judged by TUNEL assay. Apoptosis was mainly observed in proliferating SMCs in subconfluent cultures; whereas at higher confluency, cell viability was largely unaffected. Treatment with 80 microg/ml EGCG induced the tumor suppressor p53, which was functional as judged by activation of the target cyclin-dependent kinase inhibitor p21CIP1. Inhibition of p53 activity with a dominant negative mutant reduced cell death. The increase in p53 protein was due to increased stability. EGCG also induced functional nuclear factor-kappaB (NF-kappaB) complexes, and inhibition of this activity reduced the extent of cell death. Thus, EGCG inhibits growth and induces death of SMCs in a p53- and NF-kappaB-dependent manner. These results provide evidence for a new molecular mechanism whereby green tea polyphenols inhibit SMC proliferation and function to prevent the development of atherosclerosis.

65. Yan Ke Xue Bao. 2000 Sep;16(3):194-8.

Growth inhibition, induction of apoptosis by green tea constituent (-)-epigallocatechin-3-gallate in cultured rabbit lens epithelial cells.

Huang W, Li S, Zeng J, Liu Y, Wu M, Zhang M.

Zhongshan Ophthalmic Center, Sun Yat-sen University of Medical Sciences, Guangzhou 510060, China.

PURPOSE: To evaluate effect of green tea extract (-)-Epigallocatechin-3-gallate (EGCG) in cultured rabbit lens epithelial cells in order to pave a new way to postcapsular opacity (PCO) prevention. METHODS: Cell survival rate was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) coloimetric assay. Cell apoptosis was detected by electron microscopy, Hochest 33258 stain and flow cytometer. DNA fragment was detected using agarose gel electrophoresis. RESULT: Proliferation of the cultured rabbit lens epithelia cells was inhibited by EGCG in a dose and time dependent manner. Morphologic study showed that the cells became shrunk, round shaped with their nuclei condensed and broken. Apoptotic bodies were also seen under electron microscope and in Hochest 33258 stain assay 24 hours after EGCG was added to the medium. DNA ladders were shown in agarose gel electrophoresis. In flow cytometry assay, apoptosis peak was also evident. CONCLUSION: Green Tea Constituent(-)-Epigallocatechin-3-gallate could inhibit cultured rabbit lens epithelial cells proliferation by inducing their apoptosis in the concentration used by us, which indicates that it is possible to prevent PCO by using herb extract.

66. Anticancer Res. 2002 Nov-Dec;22(6C):4115-20.

Induction of p57 is required for cell survival when exposed to green tea polyphenols.

Hsu S, Yu FS, Lewis J, Singh B, Borke J, Osaki T, Athar M, Schuster G.

Department of Oral Biology and Maxillofacial Pathology, School of Dentistry, AD1443, Medical College of Georgia, Augusta, GA 30912-1126, USA. shsu@mail.mcg.edu

Green tea polyphenols (catechins) are known to induce cell death in many types of tumor cells, but how normal epithelial cells survive in the presence of polyphenols is unknown. We recently reported that green tea polyphenols potently induced a cyclin-dependent kinase inhibitor, p57/(KIP2), only in normal human epithelial cells. In this study, we investigated the correlation between p57 expression and survival/apoptosis by Western blot analysis, caspase 3 assays and morphological analysis. It was demonstrated that, in the cells that lack p57 induction, green tea polyphenols induced Apaf-1 expression along with caspase 3 activation, leading to apoptosis. In contrast, cells with polyphenol-inducible p57 maintained constant levels of Apaf-1 and proliferating cell nuclear antigen (PCNA), with basal caspase 3 activity. Retroviral-transfected, p57-expressing oral carcinoma cells showed significant resistance to green tea polyphenol-induced apoptosis. Our results suggest that p57/KIP2 is a determinant pro-survival factor for cell protection from green tea polyphenol-induced apoptosis.

67. J Biochem Mol Biol. 2003 Jan 31;36(1):66-77.

Signal transduction pathways: targets for green and black tea polyphenols.

Park AM, Dong Z.

The Hormel Institute, University of Minnesota, Austin, MN 55912, USA.

Tea is one of the most popular beverages consumed in the world and has been demonstrated to have anti-cancer activity in animal models. Research findings suggest that the polyphenolic compounds, (-)-epigallocatechin-3-gallate found primarily in green tea, and theaflavin-3,3'-digallate, a major component of black tea, are the two most effective anti-cancer factors found in tea. Several mechanisms to explain the chemopreventive effects of tea have been presented but others and we suggest that tea components target specific cell-signaling pathways responsible for regulating cellular proliferation or apoptosis. These pathways include signal transduction pathways leading to activator protein-1 (AP-1) and/or nuclear factor kappa B (NF-kappaB). AP-1 and NF-kappaB are transcription factors that are known to be extremely important in tumor promoterinduced cell transformation and tumor promotion, and both are influenced differentially by the MAP kinase pathways. The purpose of this brief review is to present recent research data from other and our laboratory focusing on the tea-induced cellular signal transduction events associated with the MAP kinase, AP-1, and NF-kappaB pathways.

68. Clin Exp Pharmacol Physiol. 2003 Jan-Feb;30(1-2):88-95.

Green tea catechins evoke a phasic contraction in rat aorta via H2O2-mediated multiple-signalling pathways.

Shen JZ, Zheng XF, Wei EQ, Kwan CY.

Department of Pharmacology, School of Medicine, Zhejiang University, Hubin Campus, Hangzhou, People's Republic of China.

1. The contractile effects of tea polyphenols (TP) and its four principle catechins, namely (-)-epicatechin (EC), (-)-epicatechin-3-gallate (ECG), (-)-epigallocatechin (EGC) and (-)-epigallocatechin-3-gallate (EGCG), on rat aorta contractility were investigated using the isometric tension recording technique. 2. At concentrations of 5-100 mg/L, TP evoked phasic contraction of rat aorta in a concentration-dependent but endothelium-independent manner. Of the four catechins tested, EGCG and EGC (3-300 micromol/L), but not EC and ECG, mimicked the contractile response to TP, suggesting that the epigallol moiety in the B ring may be associated with the contractile effect. 3. Contractions in response to EGCG and EGC were not affected by several endogenous vasoconstrictor receptor antagonists, but could be abolished by 10 micro mol/L BAPTA-AM, a membrane-permeable Ca2+ chelator, or attenuated by removal of extracellular Ca2+, suggesting the involvement of both intracellular and extracellular Ca2+ in evoking the contraction. 4. Pretreatment with non-selective Ca2+ channel antagonists mefenamic acid (10 micro mol/L), tetrandrine (30 micro mol/L) and SKF 96365 (30 micromol/L), but not nifedipine (1 micromol/L), the selective inhibitor of voltage-dependent Ca2+ channels, inhibited the contractile responses to EGC and EGCG, indicating the involvement of Ca2+ influx via non-voltage dependent Ca2+ channels. 5. Several intracellular Ca2+ channel modulators, including procaine (5 mmol/L), dantrolene (30 micromol/L) and 2-amino ethoxydiphenyl borate (50 micromol/L; an inositol 1,4,5-trisphosphate receptor inhibitor), also inhibited EGCG- and EGC-induced contractions, thus suggesting a role of intracellular Ca2+ release in these contractions. 6. Both EGCG- and EGC-induced contractions were depressed, to different degrees, by inhibitors of several receptor-coupled enzymes, including phospholipase C, protein kinase C, phospholipase A2 and tyrosine kinase. Furthermore, both EGCG- and EGC-induced contractions were completely abolished by catalase, but not by superoxide dismutase or mannitol/dimethyl sulphoxide. 7. Taken together, these data show, for the first time, that TP and its related catechins that contain an epigallol structure in the B ring, as in EGCG and EGC, exert direct contractile effects on rat aortic smooth muscle via a H2O2-mediated pathway.

69. Anticancer Res. 2002 Nov-Dec;22(6A):3373-8.

Induction of apoptosis by the green tea flavonol (-)-epigallocatechin-3-gallate in human endothelial ECV 304 cells.

Yoo HG, Shin BA, Park JC, Kim HS, Kim WJ, Chay KO, Ahn BW, Park RK, Ellis LM, Jung YD.

Chonnam University Research Institute of Medical Sciences, Chonnam National University Medical School, Kwangju, Korea.

We have previously shown that treatment with (-)-epigallocatechin-3-gallate (EGCG) inhibited vascularity and tumor growth in human colon cancer xenografts in nude mice (Jung et al: Br J Cancer 84, 2001). In this study, we examined whether endothelial cell death by EGCG is mediated by apoptosis and which molecular mechanisms are involved in this process. EGCG was found to suppress cell growth and induce apoptosis largely through mitochondrial depolarization, activation of caspase-3 and cleavage of DNA fragmentation factor-45 in human endothelial ECV 304 cells. The induction of apoptosis by EGCG was confirmed by cleaved and condensed nuclear chromatin and DNA hypoploidy. These results suggest that EGCG may exert at least part of its anticancer effect by inhibiting angiogenesis through inducing endothelial apoptosis.

70. Cancer Detect Prev. 2002;26(6):411-8.

Modification of lung cancer susceptibility by green tea extract as measured by the comet assay.

Zhang H, Spitz MR, Tomlinson GE, Schabath MB, Minna JD, Wu X.

Department of Epidemiology, The University of Texas M.D. Anderson Cancer Center Box 189 1515 Holcombe Blvd, Houston, TX 77030, USA

Green tea is widely consumed throughout the world and is known to possess various beneficial properties that may affect carcinogen metabolism, free radical scavenging, or formation of DNA adducts. Therefore, it is plausible that green tea extract may modify BPDE-induced DNA damage. In this report, we utilized the comet assay to (1) evaluate BPDE-induced DNA damage as a potential marker of cancer susceptibility and (2) assess the ability of green tea to modify BPDE-induced DNA damage. DNA damage in individual comet cells was quantified by (1) visually measuring the proportion of cells exhibiting migration versus those without and (2) the length of damaged DNA migration (comet tail). We detected a dose-response between BDPE concentration and mean comet tail length in EBV-immortalized lymphoblastiod (lymphoid) cell lines. As the concentration of BPDE increased from 0.5 to 3 microM, the length of the mean comet tail length increased proportionally in the 3590P (derived from a healthy subject) and 3640P (derived from a patient with head and neck cancer) cell lines. In separate experiments using lymphoid cells from 21 lung cancer cases and 12 healthy subjects, the mean comet tail length was significantly higher in the lung cancer cases (80.19 +/- 15.55) versus the healthy subjects (59.94 +/- 14.23) (P < 0.01). Similar findings were observed when analyzing the mean percentage of comet induced cells (84.57 +/- 8.85 and 69.04 +/- 12.50, respectively) (P < 0.01). When green tea extract was added in conjunction with BPDE, there was a notable reduction of the mean comet tail length (13.29 +/- 0.97) as compared to BPDE treatment alone (80.19 +/- 15.55) (P < 0.01) in lung cancer cases. There were no statistical differences between the baseline (no treatments) (12.74 +/- 0.63) and the green tea extract treatment (13.06 +/- 0.97) (P = 0.21). These data suggest the modification of lung cancer susceptibility by the green tea extract. Similar results were observed for the percentage of induced comet cells and the statistical trends were similar for the 12 healthy subjects. This preliminary study demonstrated that the detection of BPDE-induced DNA damage via the comet assay may be a useful biologic marker of lung cancer susceptibility. The differential effects in BPDE-induced DNA damage between lung cancer cases and healthy subjects suggests predisposed cancer susceptibility to lung cancer risk. This reports also demonstrated the chemopreventive effects of green tea extract on BPDE-induced DNA damage. These observations provide further support for the application of the comet assay in molecular epidemiologic studies.

71. Biol Pharm Bull. 2002 Dec;25(12):1513-8.

Neuroprotective effects of the green tea components theanine and catechins.

Kakuda T.

Central Research Institute, Itoen, Ltd, Shuzuoka, Japan.

The neuroprotective effects of theanine and catechins contained in green tea are discussed. Although the death of cultured rat cortical neurons was induced by the application of glutamic acid, this neuronal death was suppressed with exposure to theanine. The death of hippocampal CA1 pyramidal neurons caused by transient forebrain ischemia in the gerbil was inhibited with the ventricular preadministration of theanine. The neuronal death of the hippocampal CA3 region by kainate was also prevented by the administration of theanine. Theanine has a higher binding capacity for the AMPA/kainate receptors than for NMDA receptors, although the binding capacity in all cases is markedly less than that of glutamic acid. The results of the present study suggest that the mechanism of the neuroprotective effect of theanine is related not only to the glutamate receptor but also to other mechanisms such as the glutamate transporter, although further studies are needed. One of the onset mechanisms for arteriosclerosis, a major factor in ischemic cerebrovascular disease, is probably the oxidative alteration of low-density lipoprotein (LDL) by active oxygen species. The oxidative alterations of LDL were shown to be prevented by tea catechins. Scavenging of *O(2)(-) was also exhibited by tea catechins. The neuroprotective effects of theanine and catechins contained in green tea are a focus of considerable attention, and further studies are warranted.

72. Life Sci. 2003 Jan 17;72(9):1073-83.

Effects of green tea polyphenols on dopamine uptake and on MPP+ -induced dopamine neuron injury.

Pan T, Fei J, Zhou X, Jankovic J, Le W.

Department of Neurology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.

As antioxidants, polyphenols are considered to be potentially useful in preventing chronic diseases in man, including Parkinson's disease (PD), a disease involving dopamine (DA) neurons. Our studies have demonstrated that polyphenols extracted from green tea (GT) can inhibit the uptake of 3H-dopamine (3H-DA) and 1-methyl-4-phenylpyridinium (MPP(+)) by DA transporters (DAT) and partially protect embryonic rat mesencephalic dopaminergic (DAergic) neurons from MPP(+)-induced injury. The inhibitory effects of GT polyphenols on 3H-DA uptake were determined in DAT-pCDNA3-transfected Chinese Hamster Ovary (DAT-CHO) cells and in striatal synaptosomes of C57BL/6 mice in vitro and in vivo. The inhibitory effects on 3H-MPP(+) uptake were determined in primary cultures of embryonic rat mesencephalic DAergic cells. Inhibition of uptake for both 3H-DA and 3H-MPP(+) was dose-dependent in the presence of polyphenols. Incubation with 50 microM MPP(+) resulted in a significant loss of tyrosine-hydroxylase (TH)-positive cells in the primary embryonic mesencephalic cultures, while pretreatment with polyphenols (10 to 30 microg/ml) or mazindol (10 microM), a classical DAT inhibitor, significantly attenuated MPP(+)-induced loss of TH-positive cells. These results suggest that GT polyphenols have inhibitory effects on DAT, through which they block MPP(+) uptake and protect DAergic neurons against MPP(+)-induced injury.

73. Asia Pac J Clin Nutr. 2002;11(4):292-7.

Effect of green tea catechin on arachidonic acid cascade in chronic cadmium-poisoned rats.

Choi JH, Chang HW, Rhee SJ.

Department of Food Science and Nutrition, Catholic University of Daegu, Kyongsan-si, Korea.

The purpose of this study was to investigate the effect of green tea catechin on the cyclooxygenase and lipoxygenase pathways in chronic cadmium-poisoned rats. Sprague-Dawley male rats weighing 100 +/- 10 g were randomly assigned to one normal and three cadmium-poisoned groups. The cadmium groups were classified as catechin-free diet group (Cd-0C), 0.25% catechin diet group (Cd-0.25C) and 0.5% catechin diet group (Cd-0.5C), in accordance with the level of catechin supplement. The phospholipase A2 activity was remarkably increased 117% in the Cd-0C group and 60% in the Cd-0.25C group compared with the normal group, and the level in the Cd-0.5C group was the same as the normal group. Activity of platelet cyclooxygenase increased 284% in the Cd-0C group, 147% in the Cd-0.25C group and 193% in the Cd-0.5C group. The synthesis of platelet thromboxane A2 (TXA2) increased 157% in the Cd-0C group and 105% in the Cd-0.25C group, compared with the normal group. The Cd-0.5C group showed the same level as the normal group. Prostacyclin (PGI2) formation in the aorta decreased 24% in the Cd-0C group and 18% in the Cd-0.25C group. The ratio of PGI2/TXA2, the thrombocyte synthesis index, decreased 70% in the Cd-0C group and 59% in the Cd-0.25C group. The activity of 5'-lipoxygenase in the polymorphonuclear leukocyte was increased 40% in the Cd-0C group as compared with the normal group. Catechin-supplemented Cd-0.25C and Cd-0.5C groups showed the level of the normal group. In this study, the observed content of leukotriene B4, which induces the inflammatory process, increased 54% in the Cd-0C group, and in catechin-supplemented groups, showed the same level as in the normal group. The serum peroxide value increased 60% in the Cd-0C group compared with the normal group; but in the Cd-0.5C group, it showed the level of the normal group. These results indicate that chronic cadmium poisoning in rats accelerates arachidonic acid metabolism. Inhibition of arachidonic acid metabolism due to catechin supplementation, however, decreases platelet aggregation and inflammatory action. In conclusion, it would appear that green tea catechin supplementation in chronic cadmium-poisoned rats inhibits the arachidonic acid cascade by regulating the activity of phospholipase A2.

74. Antivir Chem Chemother. 2002 Jul;13(4):223-9.

Antiviral properties of prodelphinidin B-2 3'-O-gallate from green tea leaf.

Cheng HY, Lin CC, Lin TC.

Graduate Institute of Pharmaceutical Science, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, Taiwan, Republic of China.

Prodelphinidin B-2 3-O-gallate, a proanthocyanidin gallate isolated from green tea leaf, was investigated for its anti-herpes simplex virus type 2 properties in vitro. Prodelphinidin B-2 3'-O-gallate exhibited antiviral activity with IC50 of 5.0 +/-1.0 microM and 1.6 +/-0.3 pM for XTT and plaque reduction (PRA) assays, respectively. Cytotoxicity assay had shown that prodelphinidin B-2 3'-O-gallate possessed cytotoxic effect toward Vero cell at concentration higher than its IC50. The 50% cytotoxic concentration for cell growth (CC50) was 33.3 +/- 3.7 microM. Thus, the selectivity index (SI) (ratio of IC50 to CC50) for XTT assay and PRA was 6.7 and 20.8, respectively. Prodelphinidin B-2 3'-O-gallate significantly reduced viral infectivity at concentrations 10 microM or more. Result of time-of-addition studies suggested that prodelphinidin B-2 3'-O-gallate affected the late stage of HSV-2 infection. In addition, it was also shown to inhibit the virus from attaching and penetrating into the cell. Thus, prodelphinidin B-2 3'-O-gallate was concluded to possess antiviral activity with mechanism of inhibiting viral attachment and penetration, and disturbing the late stage of viral infection.

75. Atherosclerosis. 2003 Jan;166(1):23-30.

Green tea catechins inhibit the cultured smooth muscle cell invasion through the basement barrier.

Maeda K, Kuzuya M, Cheng XW, Asai T, Kanda S, Tamaya-Mori N, Sasaki T, Shibata T, Iguchi A.

Department of Geriatrics, Nagoya University Graduate School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya 466-8550, Japan.

Epidemiological studies suggest that green tea consumption is associated with a reduced risk of cardiovascular disease. Antioxidative properties of green tea flavonoids, catechins, have been believed to be involved in the antiatherogenic effect of green tea, since catechins inhibit low density lipoprotein oxidation. The migration of vascular smooth muscle cells (SMCs) from the tunica media to the subendothelial region is a key event in the development and progression of atherosclerosis and post-angioplasty vascular remodeling. Matrix metalloproteinases (MMPs) play a key role in these processes of SMC migration. In the present study, we investigated the effect of catechins on the gelatinolytic activity of MMP-2 that was derived from cultured bovine aortic SMCs. We also investigated the effect of catechins on the SMC invasion through the reconstituted basement membrane barrier. A major constituent of green tea catechins, (-)-epigallocatechin gallate (EGCG), inhibited the gelatinolytic activity of MMP-2 and concanavalin A (ConA)-induced pro-MMP-2 activation without the influence of membrane-type MMP expression in SMCs. EGCG also inhibited the SMC invasion through the basement membrane barrier in a concentration-dependent manner without any influence of SMC migration across the basement membrane protein thin-coated filter. The antagonistic effects of other catechins, namely (-)-epigallocatechin (EGC) and (-)-epicatechin gallate (ECG), on gelatinolytic activity of MMP-2, ConA-induced pro-MMP-2 activation, or PDGF-BB-directed SMC invasion were much less pronounced than those of EGCG. Also, (+)-catechin and (-)-epicatechin failed to show any effect. These findings may suggest that the anti-invasive and anti-metalloproteinase activities involve at least part of the anti-atherogenic action of catechin in accordance with the antioxidant properties of catechin.

76. J Periodontal Res. 2002 Dec;37(6):433-8.

Improvement of periodontal status by green tea catechin using a local delivery system: a clinical pilot study.

Hirasawa M, Takada K, Makimura M, Otake S.

Department of Microbiology, Nihon University School of Dentistry at Matsudo, Matsudo, Chiba Japan. masahira@mascat.nihon-u.ac.jp

The purpose of this study was to determine the usefulness of green tea catechin for the improvement of periodontal disease. The minimum inhibitory concentration (MIC) and bactericidal activity of green tea catechin against black-pigmented, Gram-negative anaerobic rods (BPR) were measured. Hydroxypropylcellulose strips containing green tea catechin as a slow release local delivery system were applied in pockets in patients once a week for 8 weeks. The clinical, enzymatic and microbiological effects of the catechin were determined. Green tea catechin showed a bactericidal effect against Porphyromonas gingivalis and Prevotella spp. in vitro with an MIC of 1.0 mg/ml. In the in vivo experiment, the pocket depth (PD) and the proportion of BPR were markedly decreased in the catechin group with mechanical treatment at week 8 compared with the baseline with significant difference. In contrast, PD and BPR were similar to the baseline and the value at the end of the experimental period in the placebo sites of scaled groups. The peptidase activities in the gingival fluid were maintained at lower levels during the experimental period in the test sites, while it reached 70% of that at baseline in the placebo sites. No morbidity was observed in the placebo and catechin groups without mechanical treatment. Green tea catechin showed a bactericidal effect against BPR and the combined use of mechanical treatment and the application of green tea catechin using a slow release local delivery system was effective in improving periodontal status.

77. Breast Cancer Res Treat. 2002 Dec;76(3):195-201.

(-)-Epigallocatechin (EGC) of green tea induces apoptosis of human breast cancer cells but not of their normal counterparts.

Vergote D, Cren-Olive C, Chopin V, Toillon RA, Rolando C, Hondermarck H, Le Bourhis X.

Laboratoire de Biologic du Developpement (UPRES-EA 1033), Universite des Sciences et Technologies de Lille, Villeneuve d'Ascq, France.

(-)-Epigallocatechin (EGC), one of green tea polyphenols, has been shown to inhibit growth of cancer cells. However its mechanism of action is poorly known. We show here that EGC strongly inhibited the growth of breast cancer cell lines (MCF-7 and MDA-MB-231) but not that of normal breast epithelial cells. The inhibition of breast cancer cell growth was due to an induction of apoptosis, without any change in cell cycle progression. MCF-7 cells are known to express a wild-type p53 whereas MDA-MB-231 cells express a mutated p53. The fact that EGC induced apoptosis in both these cell lines suggests that the EGC-triggered apoptosis is independent of p53 status. Moreover, neutralizing antibodies against the death receptor Fas and inhibitors of caspases, such as caspase-8 and -10, efficiently inhibited the EGC-triggered apoptosis. In addition, immunoblotting revealed that EGC treatment was correlated with a decrease in Bcl-2 and an increase in Bax level. These results suggest that EGC-triggered apoptosis in breast cancer cells requires Fas signaling.

78. Yakugaku Zasshi. 2002 Nov;122(11):995-9.

[Glutamate transporter mediated increase of antitumor activity by theanine, an amino acid in green tea]

[Article in Japanese]

Sadzuka Y, Yamashita Y, Kishimoto S, Fukushima S, Takeuchi Y, Sonobe T.

University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Japan. sadzuka@u-shizuoka-ken.ac.jp

We have confirmed that theanine, a major amino acid in green tea, enhances the antitumor activity of doxorubicin (DOX) without an increase in DOX-induced side effects. We believe that the action of theanine is due to decreases in glutamate uptake via inhibition of the glutamate transporter, intracellular glutathione (GSH) synthesis, GS-DOX conjugate level, and subsequent extracellular transport of GS-DOX by the MRP5/GS-X pump. To increase the clinical usefulness of theanine, we examined its effects on the antitumor activity of cisplatin and irinotecan (CPT-11), which a known to be transported by the efflux system related to MRP. Cisplatin decreased tumor volume in M5076 tumor-bearing mice. Furthermore, the combination of theanine with cisplatin increased the decrease in tumor volume as compared with the cisplatin-alone group. Tumor volume in the CPT-11-alone group did not show a decrease, but the combination of theanine with CPT-11 significantly reduced tumor volume. The concentration of cisplatin in the tumor was significantly increased by combination with theanine, and thus we assume that it correlated with the enhancement on the antitumor activity of theanine. On the other hand, changes in drug concentrations with theanine were not observed in normal tissues, but rather it is indicated that theanine tends to reduce their concentrations. Therefore theanine enhances the antitumor activity not only of DOX but also of cisplatin or CPT-11.

79. Int J Cancer. 2002 Dec 10;102(5):439-44.

The green tea polyphenol, epigallocatechin-3-gallate, protects against the oxidative cellular and genotoxic damage of UVA radiation.

Tobi SE, Gilbert M, Paul N, McMillan TJ.

Department of Biological Sciences, Institute of Environmental and Natural Sciences, Lancaster University, Lancaster, United Kingdom.

A number of biological activities have been ascribed to the major green tea polyphenol epigallocatechin-3-gallate (EGCG) to explain its chemopreventive properties. Its antioxidant properties emerge as a potentially important mode of action. We have examined the effect of EGCG treatment on the damaging oxidative effects of UVA radiation in a human keratinocyte line (HaCaT). Using the ROS-sensitive probes dihydrorhodamine 123 (DHR) and 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA), we detected a reduction in fluorescence in UVA-irradiated (100 kJ/m(2)) cells in the case of the former but not the latter probe after a 24-hr treatment with EGCG (e.g., 14%, [p < 0.05] after 10 microM EGCG). In the absence of UVA, however, both DHR and DCFH detected a pro-oxidant effect of EGCG at the highest concentration used of 50 microM. Measurements of DNA damage in UVA-exposed cells using the single cell gel electrophoresis assay (comet assay) also showed the protective effects of EGCG. A concentration of 10 microM EGCG decreased the level of DNA single strand breaks and alkali-labile sites to 62% of the level observed in non-EGCG, irradiated cells (p < 0.001) with a 5-fold higher concentration producing little further effect. Correspondingly, EGCG ablated the mutagenic effects of UVA (500 kJ/m(2)) reducing an induced hypoxanthine-guanine phosphoribosyl transferase (HPRT) mutant frequency of (3.39 +/- 0.73) x 10(-6) to spontaneous levels (1.09 +/- 0.19) x 10(-6). Despite having an antiproliferative effect in the absence of UVA, EGCG also served to protect against the cytotoxic effects of UVA radiation. Our data demonstrate the ability of EGCG to modify endpoints directly relevant to the carcinogenic process in skin. Copyright 2002 Wiley-Liss, Inc.

80. Int J Oncol. 2002 Dec;21(6):1307-15.

Bioactivity of well-defined green tea extracts in multicellular tumor spheroids.

Mueller-Klieser W, Schreiber-Klais S, Walenta S, Kreuter MH.

Institute of Physiology and Pathophysiology, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany. wolfgang.mueller-klieser@uni-mainz.de

The effect of green tea extracts (GTE) of a reproducible, well-defined composition on cellular viability, proliferation, and antioxidant defense was investigated in multicellular spheroids derived from WiDr human colon adenocarcinoma cells. The maximum GTE concentration investigated, i.e. 100 micro g GTE/ml, was equivalent to the plasma concentration commonly measured in humans drinking 6-10 cups of green tea per day. This GTE concentration lead to a substantial retardation of spheroid volume growth with diameters reaching only half the size of untreated aggregates. Flow cytometric analysis and immunocytochemistry showed an enhanced accumulation of cells in G2/M and in the non-proliferating compartment, respectively. The emergence of central necrosis occurred at larger spheroid diameters compared to control conditions leading to a significant increase (p<0.05) in the thickness of the viable cell rim (mean +/- SD) from 240+/-49.9 micro m to 294+/-69.5 micro m. This was associated with an elevation of the intracellular GSH concentration and, thus, of cellular antioxidant defense, as shown by HPLC analysis. A considerable toxicity, however, was found at these GTE levels in single cells. Cells did not adhere to culture dishes nor did they aggregate to form spheroids when plated as a suspension with GTE already in the culture medium. The findings show that green tea constituents interfere with early phases of tumorigenesis at a cellular level, e.g., by reducing cell-substratum and cell-cell interaction, enhancing G2/M arrest, and retarding spheroid volume growth. The differences in GTE effects between single cells and cell spheroids underline the importance of inclusion of spheroids in pharmaco-/toxicological testing.

81. Life Sci. 2002 Dec 6;72(3):257-68.

Anti-proliferative and differentiation-inducing activities of the green tea catechin epigallocatechin-3-gallate (EGCG) on the human eosinophilic leukemia EoL-1 cell line.

Lung HL, Ip WK, Wong CK, Mak NK, Chen ZY, Leung KN.

Department of Biochemistry, The Chinese University of Hong Kong, Shatin, China.

A novel approach for the treatment of leukemia is the differentiation therapy in which immature leukemia cells are induced to attain a mature phenotype when exposed to differentiation inducers, either alone or in combinations with other chemotherapeutic or chemopreventive drugs. Over the past decade, numerous studies indicated that green tea catechins (GTC) could suppress the growth and induce apoptosis on a number of human cancer cell lines. However, the differentiation-inducing activity of GTC on human tumors remains poorly understood. In the present study, the effect of the major GTC epigallocatechin-3-gallate (EGCG) on the proliferation and differentiation of a human eosinophilc leukemic cell line, EoL-1, was examined. Our results showed that EGCG suppressed the proliferation of the EoL-1 cells in a dose-dependent manner, with an estimated IC(50) value of 31.5 microM. On the other hand, EGCG at a concentration of 40 microM could trigger the EoL-1 cells to undergo morphological differentiation into mature eosinophil-like cells. Using RT-PCR and flow cytometry, it was found that EGCG upregulated the gene and protein expression of two eosinophil-specific granule proteins, the major basic protein (MBP) and eosinophil peroxidase (EPO), in EoL-1 cells. Taken together, our findings suggest that EGCG can exhibit anti-leukemic activity on a human eosinophilic cell line EoL-1 by suppressing the proliferation and by inducing the differentiation of the leukemia cells.

82. Chem Phys Lipids. 2002 Dec;120(1-2):109-17.

Antioxidant effects of green tea polyphenols on free radical initiated peroxidation of rat liver microsomes.

Cai YJ, Ma LP, Hou LF, Zhou B, Yang L, Liu ZL.

National Laboratory of Applied Organic Chemistry, Lanzhou University, Gansu 730000, Lanzhou, People's Republic of China

Antioxidative effects of the principal polyphenolic components extracted from green tea leaves, i.e. (-)-epicatechin (EC), (-)-epicatechin gallate (ECG), (-)-epigallocatechin gallate (EGCG), (-)-epigallocatechin (EGC), and gallic acid (GA), against free radical initiated peroxidation of rat liver microsomes were studied. The peroxidation was initiated by a water-soluble azo compound 2,2'-azobis(2-amidinopropane hydrochloride (AAPH). The reaction kinetics was monitored by oxygen uptake and formation of malondialdehyde (MDA). Kinetic analysis of the antioxidation process demonstrates that these green tea polyphenols (GOHs), especially EC and ECG which bear ortho-dihydroxyl functionality, are good antioxidants for microsomal peroxidation. The antioxidant synergism of these GOHs with the endogenous alpha-tocopherol (TOH) (vitamin E) is also discussed.

83. Food Chem Toxicol. 2002 Dec;40(12):1745-50.

Direct scavenging of nitric oxide and superoxide by green tea.

Nakagawa T, Yokozawa T.

Institute of Natural Medicine, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Japan.

In the present study, we investigated the free radical scavenging effects of green tea extract and green tea tannin mixture and its components using a nitric oxide (NO) and superoxide (O(2)(-)) generating system in vitro. Green tea extract showed direct scavenging activity against NO and O(2)(-) and green tea tannin mixture, at the same concentration, showed high scavenging activity. Comparison of the activities of seven pure compounds isolated from green tea tannin mixture showed that (-)-epigallocatechin 3-O-gallate (EGCg), (-)-gallocatechin 3-O-gallate (GCg) and (-)-epicatechin 3-O-gallate (ECg) had higher scavenging activities than (-)-epigallocatechin (EGC), (+)-gallocatechin (GC), (-)-epicatechin (EC) and (+)-catechin (C), showing the importance of the structure of flavan-3-ol linked to gallic acid for this activity. Among the gallate-free tannins, EGC and GC were more effective O(2)(-) scavengers than EC and C, indicating the O-trihydroxy structure in the B ring is an important determinant of such activity. However, this structure did not affect the NO scavenging activity. These findings confirm that green tea tannin has excellent antioxidant properties, which may be involved in the beneficial effect of this compound.

84. J Ethnopharmacol. 2002 Nov;83(1-2):109-16.

Anti-diabetic activity of green tea polyphenols and their role in reducing oxidative stress in experimental diabetes.

M C S, K S, Kuttan R.

Amala Cancer Research Centre, Amala Nagar,Trichur 680 553, Kerala, India.

An aqueous solution of green tea polyphenols (GTP) was found to inhibit lipid peroxidation (LP), scavenge hydroxyl and superoxide radicals in vitro. Concentration needed for 50% inhibition of superoxide, hydroxyl and LP radicals were 10, 52.5 and 136 micro g/ml, respectively. Administration of GTP (500 mg/kg b.wt.) to normal rats increased glucose tolerance significantly (P<0.005) at 60 min. GTP was also found to reduce serum glucose level in alloxan diabetic rats significantly at a dose level of 100 mg/kg b.wt. Continued daily administration (15 days) of the extract 50, 100 mg/kg b.wt. produced 29 and 44% reduction in the elevated serum glucose level produced by alloxan administration. Elevated hepatic and renal enzymes produced by alloxan were found to be reduced (P<0.001) by GTP. The serum LP levels which was increased by alloxan and was reduced by significantly (P<0.001) by the administration of 100 mg/kg b.wt. of GTP. Decreased liver glycogen, after alloxan administration showed a significant (P<0.001) increase after GTP treatment. GTP treated group showed increased antioxidant potential as seen from improvements in superoxide dismutase and glutathione levels. However catalase, LP and glutathione peroxidase levels were unchanged. These results indicate that alterations in the glucose utilizing system and oxidation status in rats increased by alloxan were partially reversed by the administration of the glutamate pyruvate transaminase.

85. Zhonghua Yu Fang Yi Xue Za Zhi. 2002 Jul;36(4):243-6.

[Green tea extracts protected against carbon tetrachloride-induced chronic liver damage and cirrhosis]

[Article in Chinese]

Xiao J, Lu R, Shen X, Wu M.

Department of Hutyition and Food Hygiene, School of Health, Fudan University, Shanghai 200032, China.

OBJECTIVE: Using the carbon tetrachloride liver cirrhosis rat model, the protective effect of the green tea extractive (GTE) on the liver cirrhosis was studied. METHODS: Male SD rats were randomly divided into three groups: normal group, GTE group and cirrhosis group. The GTE group and the cirrhosis group were injected subcutanuously 2 times/wk over 9 weeks with 40% CCl(4). In the second and the ninth week, the rats were sacrificed to measure MDA and hydroxyproline concentrations and TGF-beta(1) mRNA expression in liver tissue, as well as to conduct histological examination on various organs. RESULTS: Compared with the cirrhosis group, the MDA and the hydroxyproline concentrations in the GTE group were significantly reduced (P < 0.05). The liver necrosis and cirrhosis were extenuated in the GTE group by means of histologic examination. The expression of the TGF-beta(1) mRNA was reduced significantly in the GTE group. CONCLUSION: Dietary supplementation of GTE can protect against CCl(4)-induced liver damage and cirrhosis in rats.

86. Cancer Lett. 2002 Dec 15;188(1-2):163-70.

Lack of inhibitory effects of green tea catechins in 1,2-dimetylhydrazine-induced rat intestinal carcinogenesis model: comparison of the different formulations, administration routes and doses.

Hirose M, Yamaguchi T, Mizoguchi Y, Akagi K, Futakuchi M, Shirai T.

Division of Pathology, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, 158-8501, Tokyo, Japan. m-hirose@nihs.go.jp

Differences in the modifying effects of green tea catechins (GTC) on intestinal carcinogenesis by different formulations, doses and administration routes were investigated in male rats pretreated with 1,2-dimethylhydrazine (DMH). One hundred and eighty nine F344 male rats received subcutaneous injections of DMH at 40 mg/kg body weight twice a week for 3 weeks. Three days after completion of the carcinogen treatment, they were divided into nine groups. Each was administered a different source of 0.1% or 0.01% of GTC (Mitsui Norin Co. (M) or Taiyo Kagaku Co. (T)) either in the diet (D) or the drinking water (W), or basal diet and tap water alone without GTC for 33 weeks and then killed for autopsy. The survival rate tended to be lower with 0.01% MGTC (W) group than in the other groups. In the large intestine, although the multiplicity and/or incidences of adenomas showed tendencies for dose-dependent decrease in all GTC groups, and the average volumes of tumors tended to be decrease dose-dependently in the MGTC (W) and TGTC (W) groups, the multiplicity of carcinomas did not show such a trend, rather being significantly increased in the 0.01% MGTC (D) and 0.1% TGTC (W) groups. In the small intestine, the incidence and the multiplicity of tumors in all GTC treated groups had a tendency to decrease. On the other hand, the volume of tumors was increased with statistical significance in the 0.01% MGTC (W) and 0.1% TGTC (W) groups. Thus it can be concluded that GTC does not exert chemopreventive effects on intestinal carcinogenesis irrespective of its formulation, dose or route of administration.

87. Cancer Lett. 2002 Dec 15;188(1-2):9-13.

Green tea: cancer preventive beverage and/or drug.

Fujiki H, Suganuma M, Imai K, Nakachi K.

Department of Biochemistry, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, 770-8514, Tokushima, Japan. hfujiki@ph.bunri-u.ac.jp

Green tea and (-)-epigallocatechin gallate (EGCG) are now acknowledged cancer preventives in Japan and has made it possible for us to establish the concept of a cancer preventive beverage. For the general population, we recommend 10 cups of green tea daily supplemented with green tea tablets. For cancer patients following treatment, we here present new evidence that green tea and a cancer preventive drug, sulindac, have synergistic preventive effects. An approach to develop green tea capsules as a cancer preventive drug in the US is discussed, aiming at taking full advantage of this cancer preventive beverage.

88. Amino Acids. 2002;22(2):131-43.

The specific anti-cancer activity of green tea (-)-epigallocatechin-3-gallate (EGCG).

Wang YC, Bachrach U.

Department of Molecular Biology, Hebrew University-Hadassah Medical School, Jerusalem, Israel.

The effect of the green tea polyphenol-(-)epigallocatechin-3-gallate (EGCG) was tested in cultures of normal and transformed NIH-pATM ras fibroblasts. In this system transformation can be induced at will by the addition of dexamethasone, which induces the expression of H- ras by activating the mammary tumor virus long terminal repeat (MMTV-LTR) promoter. This facilitates a reliable comparison of the susceptibility of normal and transformed cells to EGCG. It has been shown that EGCG inhibited the growth of transformed but not of the normal fibroblasts. In an attempt to elucidate the mode of the preferential inhibitory activity of EGCG, its effect on growth promoting factors has been examined. The level of ornithine decarboxylase (ODC, EC 4.1.1.17), which is a signal for cellular proliferation, was reduced by EGCG in the transformed but not in the normal cells. EGCG also showed strong inhibition of tyrosine kinase and mitogen-activated protein kinase (MAPK) activities, without affecting the kinases in the normal cells. Similarly, EGCG also preferentially decreased the levels of the oncogenes Ras and Jun in transformed cell. EGCG preferentially induced apoptosis in the transformed fibroblasts. In vitro chemosensitivity tests demonstrated that EGCG inhibited the proliferation of leukemic cells. These findings suggest that EGCG has a therapeutic potential in the combat against cancer.

89. Mol Med. 2002 Jul;8(7):382-92.

Synthetic analogs of green tea polyphenols as proteasome inhibitors.

Smith DM, Wang Z, Kazi A, Li LH, Chan TH, Dou QP.

Drug Discovery Program, H Lee Moffitt Cancer Center & Research Institute, Departments of Interdisciplinary Oncology and Biochemistry & Molecular Biology, College of Medicine,University of South Florida, Tampa, FL 33612-9497, USA.

BACKGROUND: Animal, epidemiological and clinical studies have demonstrated the anti-tumor activity of pharmacological proteasome inhibitors and the cancer-preventive effects of green tea consumption. Previously, one of our laboratories reported that natural ester bond-containing green tea polyphenols (GTPs), such as (-)-epigallocatechin-3-gallate [(-)-EGCG] and (-)-gallocatechin-3-gallate [(-)-GCG], are potent and specific proteasome inhibitors. Another of our groups, for the first time, was able to enantioselectively synthesize (-)-EGCG as well as other analogs of this natural GTP. Our interest in designing and developing novel synthetic GTPs as proteasome inhibitors and potential cancer-preventive agents prompted our current study. MATERIALS AND METHODS: GTP analogs, (+)-EGCG, (+)-GCG, and a fully benzyl-protected (+)-EGCG [Bn-(+)-EGCG], were prepared by enantioselective synthesis. Inhibition of the proteasome or calpain (as a control) activities under cell-free conditions were measured by fluorogenic substrate assay. Inhibition of intact tumor cell proteasome activity was measured by accumulation of some proteasome target proteins (p27, I kappa B-alpha and Bax) using Western blot analysis. Inhibition of tumor cell proliferation and induction of apoptosis by synthetic GTPs were determined by G(1) arrest and caspase activation, respectively. Finally, inhibition of the transforming activity of human prostate cancer cells by synthetic GTPs was measured by a colony formation assay. RESULTS: (+)-EGCG and (+)-GCG potently and specifically inhibit the chymotrypsin-like activity of purified 20S proteasome and the 26S proteasome in tumor cell lysates, while Bn-(+)-EGCG does not. Treatment of leukemic Jurkat T or prostate cancer LNCaP cells with either (+)-EGCG or (+)-GCG accumulated p27 and IkappaB-alpha proteins, associated with an increased G(1) population. (+)-EGCG treatment also accumulated the pro-apoptotic Bax protein and induced apoptosis in LNCaP cells expressing high basal levels of Bax, but not prostate cancer DU-145 cells with low Bax expression. Finally, synthetic GTPs significantly inhibited colony formation by LNCaP cancer cells. CONCLUSIONS: Enantiomeric analogs of natural GTPs, (+)-EGCG and (+)-GCG, are able to potently and specifically inhibit the proteasome both, in vitro and in vivo, while protection of the hydroxyl groups on (+)-EGCG renders the compound completely inactive.

90. Neurotoxicology. 2002 Sep;23(3):289-300.

Differential modulation of growth and glutathione metabolism in cultured rat astrocytes by 4-hydroxynonenal and green tea polyphenol, epigallocatechin-3-gallate.

Ahmed I, John A, Vijayasarathy C, Robin MA, Raza H.

Department of Anatomy, Faculty of Medicine and Health Sciences, UAE University, Al Ain, United Arab Emirates.

Oxidative stress has been implicated in the pathogenesis of cancer and prominent neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. Apoptosis and cell cycle deregulation appear to be the mode of cell death in these disorders. Green tea polyphenol, epigallocatechin-3-gallate (EGCG) has been shown to be a potent antiinflammatory, apoptotic and cancer chemopreventive agent. 4-Hydroxynonenal (HNE), a by-product of lipid peroxidation (LPO), has been reported to induce apoptosis and inhibit growth in many cell systems including neuroglial cultures. We have studied both the dose and time dependent effects of HNE and EGCG on the viability of primary astrocyte cell cultures prepared from neonatal rats. HNE was found to be cytotoxic at a higher dose (0.1 mM) and markedly reduced (up to 80%) the astrocyte viability while EGCG did not appear to be cytotoxic under similar conditions. In addition, we have also studied the alterations in glutathione (GSH) and LPO levels and the activities of GSH metabolizing enzymes after treatment with HNE and EGCG. A 40% decrease in GSH level and a moderate increase in LPO were observed in HNE treated cells suggesting an increase in oxidative stress. HNE treatment caused a 50% decrease in GSH reductase and a 35% increase in GSH peroxidase activities. Although HNE treatment did not lead to any significant alterations in GSH-S-transferase (GST) activity, an increased expression of GST isoenzymes was seen following the exposure to HNE. EGCG treatment caused a significant increase in LPO even in the presence of elevated GSH content. In contrast to HNE, EGCG treatment resulted in a significant decrease (50%) in the activity and expression of GSTs. Treatment of astrocyte cultures with HNE, resulted in a severe impairment in mitochondrial respiration as measured by MTT exclusion assay, while treatment with EGCG had no effect on mitochondrial respiratory activity. Both HNE and EGCG were found to initiate apoptosis in astrocytes as measured by DNA fragmentation assay. However, HNE seems to be a stronger apoptotic and cytotoxic agent than EGCG. These results suggest that HNE and EGCG differentially modulate oxidative stress and regulate the growth and survival of astrocytes.

91. Drug Metab Dispos. 2002 Nov;30(11):1246-9.

Contribution of presystemic hepatic extraction to the low oral bioavailability of green tea catechins in rats.

Cai Y, Anavy ND, Chow HH.

College of Pharmacy, University of Arizona, Tucson, Arizona 85724, USA.

Green tea and green tea catechins have been shown to possess potent cancer-preventive activities in rodent cancer models. At present, epidemiological evidence of the protective effect of green tea consumption against the development of human cancers is not conclusive. Oral bioavailability of green tea catechins has been shown to be low in animals and possibly in humans. This study is designed to determine the contribution of first-pass hepatic elimination to the low oral bioavailability of green tea catechins. Green tea catechin mixture was dosed to rats by intravenous or intraportal infusion. Blood samples were collected after dosing and analyzed using high-performance liquid chromatography with the coulometric electrode array detection system. The systemic clearance of epigallocatechin gallate (EGCG), epigallocatechin (EGC), and epicatechin (EC) was 8.9, 6.3, and 9.4 ml/min, respectively. The steady state volume of distribution (V(ss)) of EGCG, EGC, and EC was 432, 220, and 187 ml, respectively. We found that high percentage of green tea catechins escaped first-pass hepatic elimination, with 87.0, 108.3, and 94.9% of EGCG, EGC, and EC, respectively, available in the systemic blood following intraportal infusion. Our results suggest that factors within the gastrointestinal tract such as limited membrane permeability, transporter mediated intestinal secretion, or gut wall metabolism may contribute more significantly to the low oral bioavailability of green tea catechins.

92. Cancer Epidemiol Biomarkers Prev. 2002 Oct;11(10 Pt 1):1025-32.

Pharmacokinetics of tea catechins after ingestion of green tea and (-)-epigallocatechin-3-gallate by humans: formation of different metabolites and individual variability.

Lee MJ, Maliakal P, Chen L, Meng X, Bondoc FY, Prabhu S, Lambert G, Mohr S, Yang CS.

Laboratory for Cancer Research, College of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854-8020, USA.

Green tea and tea polyphenols have been studied extensively as cancer chemopreventive agents in recent years. The bioavailability and metabolic fate of tea polyphenols in humans, however, are not clearly understood. In this report, the pharmacokinetic parameters of (-)-epigallocatechin-3-gallate (EGCG), (-)-epigallocatechin (EGC), and (-)-epicatechin (EC) were analyzed after administration of a single oral dose of green tea or decaffeinated green tea (20 mg tea solids/kg) or EGCG (2 mg/kg) to eight subjects. The plasma and urine levels of total EGCG, EGC, and EC (free plus conjugated forms) were quantified by HPLC coupled to an electrochemical detector. The plasma concentration time curves of the catechins were fitted in a one-compartment model. The maximum plasma concentrations of EGCG, EGC, and EC in the three repeated experiments with green tea were 77.9 +/- 22.2, 223.4 +/- 35.2, and 124.03 +/- 7.86 ng/ml, respectively, and the corresponding AUC values were 508.2 +/- 227, 945.4 +/- 438.4, and 529.5 +/- 244.4 ng x h x ml(-1), respectively. The time needed to reach the peak concentrations was in the range of 1.3-1.6 h. The elimination half-lives were 3.4 +/- 0.3, 1.7 +/- 0.4, and 2.0 +/- 0.4 h, respectively. Considerable interindividual differences and variations between repeated experiments in the pharmacokinetic parameters were noted. Significant differences in these pharmacokinetic parameters were not observed when EGCG was given in decaffeinated green tea or in pure form. In the plasma, EGCG was mostly present in the free form, whereas EGC and EC were mostly in the conjugated form. Over 90% of the total urinary EGC and EC, almost all in the conjugated forms, were excreted between 0 and 8 h. Substantial amounts of 4'-O-methyl EGC, at levels higher than EGC, were detected in the urine and plasma. The plasma level of 4'-O-methyl EGC peaked at 1.7 +/- 0.5 h with a half life of 4.4 +/- 1.1 h. Two ring-fission metabolites, (-)-5-(3',4',5'-trihydroxyphenyl)-gamma-valerolactone (M4) and (-)-5-(3',4'-dihydroxyphenyl)-valerolactone (M6), appeared in significant amounts after 3 h and peaked at 8-15 h in the urine as well as in the plasma. These results may be useful for designing the dose and dose frequency in intervention studies with tea and for development of biomarkers of tea consumption.

93. Free Radic Biol Med. 2002 Oct 15;33(8):1097-105.

Green tea polyphenol epigallocatechin-3-gallate inhibits the IL-1 beta-induced activity and expression of cyclooxygenase-2 and nitric oxide synthase-2 in human chondrocytes.

Ahmed S, Rahman A, Hasnain A, Lalonde M, Goldberg VM, Haqqi TM.

Department of Orthopedics, Case Western Reserve University, Cleveland, OH 44106-4946, USA.

We have previously shown that green tea polyphenols inhibit the onset and severity of collagen II-induced arthritis in mice. In the present study, we report the pharmacological effects of green tea polyphenol epigallocatechin-3-gallate (EGCG), on interleukin-1 beta (IL-1 beta)-induced expression and activity of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in human chondrocytes derived from osteoarthritis (OA) cartilage. Stimulation of human chondrocytes with IL-1 beta (5 ng/ml) for 24 h resulted in significantly enhanced production of nitric oxide (NO) and prostaglandin E(2) (PGE(2)) when compared to untreated controls (p <.001). Pretreament of human chondrocytes with EGCG showed a dose-dependent inhibition in the production of NO and PGE(2) by 48% and 24%, respectively, and correlated with the inhibition of iNOS and COX-2 activities (p <.005). In addition, IL-1 beta-induced expression of iNOS and COX-2 was also markedly inhibited in human chondrocytes pretreated with EGCG (p <.001). Parallel to these findings, EGCG also inhibited the IL-1 beta-induced LDH release in chondrocytes cultures. Overall, the study suggests that EGCG affords protection against IL-1 beta-induced production of catabolic mediators NO and PGE(2) in human chondrocytes by regulating the expression and catalytic activity of their respective enzymes. Furthermore, our results also indicate that ECGC may be of potential therapeutic value for inhibiting cartilage resorption in arthritic joints.

94. Ophthalmic Res. 2002 Jul-Aug;34(4):258-63.

Green tea (Camellia sinensis) protects against selenite-induced oxidative stress in experimental cataractogenesis.

Gupta SK, Halder N, Srivastava S, Trivedi D, Joshi S, Varma SD.

Department of Pharmacology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India. skgup@hotmail.com

Cataract is the leading cause of blindness worldwide. It is a multifactorial disease primarily associated with oxidative stress produced by free radicals. The protection offered by various antioxidants in cataract development is well established. Polyphenolic compounds present in green tea (Camellia sinensis) are reported to possess antioxidant property in various pathological conditions. The present study was undertaken to evaluate the anticataract potential of green tea leaf (GTL) extract in the development of lens opacification. Enucleated rat lenses were randomly divided into normal, control and treated groups and incubated for 24 h at 37 degrees C. Oxidative stress was induced by sodium selenite in the culture medium of the two groups (except the normal group). The medium of the treated group was additionally supplemented with GTL extract. After incubation, lenses were subjected to glutathione and malondialdehyde estimation. Enzyme activity of superoxide dismutase, catalase and glutathione peroxidase was also measured in different sets of the experiment. In vivo cataract was induced in 9-day-old rat pups of both control and treated groups by a single subcutaneous injection of sodium selenite. The treated pups were injected GTL extract intraperitoneally prior to selenite challenge and continued for 2 consecutive days thereafter. Cataract incidence was evaluated on 16th postnatal day by slit lamp examination. There was positive modulation of biochemical parameters in the organ culture study. Green tea was also found to reduce the incidence of selenite cataract in vivo. The results suggest that green tea possesses significant anticataract potential and acts primarily by preserving the antioxidant defense system. Copyright 2002 S. Karger AG, Basel

95. Inflammation. 2002 Oct;26(5):233-41.

A green tea-derived polyphenol, epigallocatechin-3-gallate, inhibits IkappaB kinase activation and IL-8 gene expression in respiratory epithelium.

Chen PC, Wheeler DS, Malhotra V, Odoms K, Denenberg AG, Wong HR.

Division of Critical Care Medicine, Children's Hospital Medical Center and Children's Hospital Research Foundation, Cincinnati, OH 45244, USA.

Interleukin-8 (IL-8) is a principle neutrophil chemoattractant and activator in humans. There is interest in developing novel pharmacological inhibitors of IL-8 gene expression as a means for modulating inflammation in disease states such as acute lung injury. Herein we determined the effects of epigallocatechin-3-gallate (EGCG), a green tea-derived polyphenol, on tumor necrosis factor-alpha (TNF-alpha)-mediated expression of the IL-8 gene in A549 cells. EGCG inhibited TNF-alpha-mediated IL-8 gene expression in a dose response manner, as measured by ELISA and Northern blot analysis. This effect appears to primarily involve inhibition of IL-8 transcription because EGCG inhibited TNF-alpha-mediated activation of the IL-8 promoter in cells transiently transfected with an IL-8 promoter-luciferase reporter plasmid. In addition, EGCG inhibited TNF-alpha-mediated activation of IkappaB kinase and subsequent activation of the IkappaB alpha/NF-kappaB pathway. We conclude that EGCG is a potent inhibitor of IL-8 gene expression in vitro. The proximal mechanism of this effect involves, in part, inhibition of IkappaB kinase activation.

96. Biochem Biophys Res Commun. 2002 Sep 20;297(2):412-8.

Elevation of P-glycoprotein function by a catechin in green tea.

Wang EJ, Barecki-Roach M, Johnson WW.

Drug Metabolism and Pharmacokinetics, Schering-Plough Research Institute, Lafayette, NJ 07848, USA.

The ABC transporter P-glycoprotein (P-gp) exerts a critical role in the systemic disposition of and exposure to lipophilic and amphipathic drugs, carcinogens, toxins, and other xenobiotics. The ability of P-gp to transfer a wide variety of structurally unrelated compounds from the cell interior across the membrane bilayer remains intriguing. Since dietary chemicals in green tea (and several other foods) appear to exert anticarcinogenic effects by an unknown mechanism, the constituents are frequently studied for interactions with various biomacromolecules as well as cytotoxins or isolated cells. We characterized several green tea catechins for their interaction with P-gp and their specific effects on P-gp export activity of several marker substrates. Some of these compounds inhibit the active efflux of the fluorescent markers LDS-751 (LDS) and rhodamine 123 (Rho) with low potency. Remarkably, others of these catechins facilitate the P-gp-mediated transport of LDS without affecting daunorubicin (DNR) transport or Rho. Moreover, (-)epicatechin, though an inhibitor of Rho transport, can significantly enhance the active net transport of another P-gp marker substrate, LDS. This result indicates that (-)epicatechin may bind to and activate an allosteric site that enhances P-gp overall function or efficiency. Such a mechanism of heterotropic allosteric enhancement of P-gp could serve as chemoprotective to many cells and contribute to the purported anticarcinogenic effect of green tea consumption.

97. Asia Pac J Clin Nutr. 2002;11(3):232-6.

Effects of green tea catechin on prostaglandin synthesis of renal glomerular and renal dysfunction in streptozotocin-induced diabetic rats.

Rhee SJ, Kim MJ, Kwag OG.

Department of Food Science and Nutrition, Catholic University of Daegu, Gyungsan-si, Gyungbuk, Korea. sjrhee@cataegu.ac.kr

The purpose of the present study was to investigate the effects of green tea catechin on prostaglandin synthesis of renal glomerular and renal dysfunction in rats with streptozotocin-induced diabetes. Sprague-Dawley rats weighing 100 +/- 10 g were randomly assigned to one normal group and three groups with streptozotocin-induced diabetes. The diabetic groups were classified to a catechin-free diet (DM group), a 0.25% catechin diet (DM-0.25C group) and a 0.5% catechin diet (DM-0.5C group) according to the levels of catechin supplement in their diet. The animals were maintained on an experimental diet for 4 weeks. At this point, they were injected with streptozotocin to induce diabetes. They were killed on the sixth day. The catechin supplementation groups (DM-0.25C, DM-0.SC groups) showed a decrease in thromboxane A2 synthesis but an increase in prostacyclin synthesis, compared to the DM group. The ratio of prostacyclin/thromboxane A2 was 53.3% and 38.1% lower in the DM and DM-0.25C groups, respectively, than in the normal group. The ratio in the DM-0.5C group did not differ from that in the normal group. The glomerular filtration rate in catechin feeding groups (DM-0.25C and DM-0.5C groups) was maintained at the normal level. The urinary beta2-microglobulin content in the DM-0.5C group was significantly lower than that in the normal group. On the sixth day after induction of diabetes, the urinary microalbumin content in the DM, DM-0.25C and DM-0.5C groups had increased 5.40, 4.02, 3.87 times, respectively, compared with the normal group. In conclusion, kidney function appears to be improved by green tea catechin supplementation due to its antithrombotic action, which in turn controls the arachidonic acid cascade system.

98. Biol Pharm Bull. 2002 Sep;25(9):1238-40.

Activity-guided fractionation of green tea extract with antiproliferative activity against human stomach cancer cells.

Kinjo J, Nagao T, Tanaka T, Nonaka G, Okawa M, Nohara T, Okabe H.

kinjojun@fukuoka-u.ac.jp

Epidemiological studies have suggested that the consumption of green tea provides protection against stomach cancer. Fractionation of green tea extract, guided by antiproliferative activity against human stomach cancer (MK-1) cells, has resulted in the isolation of six active flavan-3-ols, epicatechin (EC), epigallocatechin (EGC), epigallocatechin gallate (EGCg), gallocatechin (GC), epicatechin gallate (ECg), gallocatechin gallate (GCg), together with inactive glycosides of kaempferol and quercetin. Among the six active flavan-3-ols, EGCg and GCg showed the highest activity, EGC, GC, ECg followed next, and the activity of EC was lowest. These data suggest that the presence of the three adjacent hydroxyl groups (pyrogallol or galloyl group) in the molecule would be a key factor for enhancing the activity. Since reactive oxygen species play an important role in cell death induction, radical scavenging activity was evaluated using the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical. The order of scavenging activity was ECg > or = EGCg > or = EGC > or = GC > or = EC. The compounds having a galloyl moiety showed more potent activity. The contribution of the pyrogallol moiety in the B-ring to the scavenging activity seemed to be less than that of the galloyl moiety.

99. Am J Physiol Gastrointest Liver Physiol. 2002 Oct;283(4):G957-64.

Prevention of hepatic ischemia-reperfusion injury by green tea extract.

Zhong Z, Froh M, Connor HD, Li X, Conzelmann LO, Mason RP, Lemasters JJ, Thurman RG.

Department of Cell and Developmental Biology, University of North Carolina at Chapel Hill, 27599, USA.

These experiments were designed to determine whether green tea extract (GTE), which contains polyphenolic free radical scavengers, prevents ischemia-reperfusion injury to the liver. Rats were fed a powdered diet containing 0-0.3% GTE starting 5 days before hepatic warm ischemia and reperfusion. Free radicals in bile were trapped with the spin-trapping reagent alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN) and measured using electron spin resonance spectroscopy. Hepatic ischemia-reperfusion increased transaminase release and caused pathological changes including focal necrosis and hepatic leukocyte infiltration in the liver. Transaminase release was diminished by over 85% and pathological changes were almost totally blocked by 0.1% dietary GTE. Ischemia-reperfusion increased 4-POBN/radical adducts in bile nearly twofold, an effect largely blocked by GTE. Epicatechin, one of the major green tea polyphenols, gave similar protection as GTE. In addition, hepatic ischemia-reperfusion activated NF-kappa B and increased TNF-alpha mRNA and protein expression. These effects were all blocked by GTE. Taken together, these results demonstrate that GTE scavenges free radicals in the liver after ischemiareoxygenation, thus preventing formation of toxic cytokines. Therefore, GTE could prove to be effective in decreasing hepatic injury in disease states where ischemia-reperfusion occurs.

100. Mutat Res. 2002 Sep;512(1):37-65.

Comparative antimutagenic and anticlastogenic effects of green tea and black tea: a review.

Gupta S, Saha B, Giri AK.

Division of Human Genetics and Genomics, Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Jadavpur, Calcutta 700 032, India.

Tea is the most popular beverage next to water, consumed by over two-thirds of the world's population. It is processed in different ways in different parts of the world to give green, black or oolong tea. Experimental studies have demonstrated the significant antimutagenic and anticlastogenic effects of both green and black tea and its polyphenols in multiple mutational assays. In the present review, we have attempted to evaluate and update the comparative antimutagenic and anticlastogenic effects of green tea, black tea and their polyphenols in different test systems, based on available literature. Existing reports have suggested that the protective effects of black tea is as good as green tea, however, more studies on black tea and its polyphenols are needed before a final conclusion can be made.

101. Mol Cell Biochem. 2002 Jul;236(1-2):173-81.

Protective effect of green tea extract against the erythrocytic oxidative stress injury during mycobacterium tuberculosis infection in mice.

Guleria RS, Jain A, Tiwari V, Misra MK.

Department of Microbiology, K. G's. Medical College, Lucknow, UP, India.

The present study has been undertaken to monitor the extent of oxidative stress in mice infected with M tuberculosis and the role of crude green tea extract in repairing the oxidative damage. The mice were divided into three groups of 9 each; normal, infected-untreated and infected-treated. The infected group of animals exhibited significant enhancement of erythrocytic catalase and glutathione peroxidase activities along with elevated levels of erythrocytic total thiols and plasma lipid peroxidation as compared to normal animals. The infected group also exhibited significantly decreased activity of superoxide dismutase and levels of glutathione in erythrocytes. Upon oral administration of green tea extract for seven days the oxidative stress parameters were reverted back to near normal levels as evidenced by a fall in catalase, glutathione peroxidase, total thiol and extent of lipid peroxidation with concomitant increase in the levels of SOD and reduced glutathione in infected animals. The findings thus, portray that there is a high oxidative stress during early stages of tuberculosis and antioxidants such as green tea extract, can play a vital role by reducing stress through adjuvant therapy.

102. Redox Rep. 2002;7(3):171-7.

Protective effects of green tea polyphenols and their major component, (-)-epigallocatechin-3-gallate (EGCG), on 6-hydroxydopamine-induced apoptosis in PC12 cells.

Nie G, Cao Y, Zhao B.

Laboratory of Visual Information Processing, Department of Molecular and Cell Biophysics, Institute of Biophysics, Academia Sinica, 15 Datun Road, Chaoyang District, Beijing 100101, P.R. China.

Green tea polyphenols exert a wide range of biochemical and pharmacological effects, and have been shown to possess antimutagenic and anticarcinogenic properties. Oxidative stress is involved in the pathogenesis of Parkinson's disease. However, although green tea polyphenols may be expected to inhibit the progression of Parkinson's disease on the basis of their known antioxidant activity, this has not previously been established. In the present study, we evaluated the neuroprotective effects of green tea polyphenols in the Parkinson's disease pathological cell model. The results show that the natural antioxidants have significant inhibitory effects against apoptosis induced by oxidative stress. 6-Hydroxydopamine (6-OHDA)-induced apoptosis in catecholaminergic PC12 cells was chosen as the in vitro model of Parkinson's disease in our study. Apoptotic characteristics of PC12 cells were assessed by MTT assay, flow cytometry, fluorescence microscopy and DNA fragmentation. Green tea polyphenols and their major component, EGCG at a concentration of 200 microM, exert significant protective effects against 6-OHDA-induced PC12 cell apoptosis. EGCG is more effective than the mixture of green tea polyphenols. The antioxidant function of green tea polyphenols may account for this neuroprotective effect. The present study supports the notion that green tea polyphenols have the potential to be effective as neuropreventive agents for the treatment of neurodegenerative diseases.

103. Br J Cancer. 2002 Jul 29;87(3):309-13.

A prospective study of stomach cancer death in relation to green tea consumption in Japan.

Hoshiyama Y, Kawaguchi T, Miura Y, Mizoue T, Tokui N, Yatsuya H, Sakata K, Kondo T, Kikuchi S, Toyoshima H, Hayakawa N, Tamakoshi A, Ohno Y, Yoshimura T; Japan Collaborative Cohort Study Group.

Department of Public Health, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa, Tokyo 142-8555, Japan. yhkiss@med.showa-u.ac.jp

To evaluate whether green tea consumption provides protection against stomach cancer death, relative risks were calculated using Cox proportional hazards regression analysis in the Japan Collaborative Study for Evaluation of Cancer Risk, sponsored by the Ministry of Health and Welfare (JACC Study). The study was based on 30 370 men and 42 481 women aged 40-79. After adjustment for age, smoking status, history of peptic ulcer, family history of stomach cancer along with certain dietary items, the risks associated with drinking one or two, three or four, five to nine, and 10 or more cups of green tea per day, relative to those of drinking less than one cup per day, were 1.6 (95% CI: 0.9-2.9), 1.1 (95% CI: 0.6-1.9), 1.0 (95% CI: 0.5-2.0), and 1.0 (95% CI: 0.5-2.0), respectively, in men (P for trend=0.669), and 1.1 (95% CI: 0.5-2.5), 1.0 (95% CI: 0.5-2.5), 0.8 (95% CI: 0.4-1.6), and 0.8 (95% CI: 0.3-2.1), respectively, in women (P for trend=0.488). We found no inverse association between green tea consumption and the risk of stomach cancer death. Copyright 2002 Cancer Research UK

104. Biochem Biophys Res Commun. 2002 Aug 23;296(3):584-8.

Inhibition of beta-catenin/Tcf activity by white tea, green tea, and epigallocatechin-3-gallate (EGCG): minor contribution of H(2)O(2) at physiologically relevant EGCG concentrations.

Dashwood WM, Orner GA, Dashwood RH.

Linus Pauling Institute, Oregon State University, Corvallis, OR 97331-6512, USA.

Epigallocatechin-3-gallate (EGCG) is the major polyphenol present in white tea and green tea. Recently, it was reported that the addition of EGCG and other tea polyphenols to cell culture media, minus cells, generated significant levels of H(2)O(2), with the corollary that this might represent an "artifact" in cell culture studies which seek to examine the chemopreventive mechanisms of tea. We show here that in cell growth media with and without serum, and in growth media containing human embryonic kidney 293 (HEK293) cells plus serum, physiologically relevant concentrations of EGCG (< or =25 microM) generated H(2)O(2) with a peak concentration of the order of 10-12 microM. However, addition of 20 microM H(2)O(2) directly to HEK293 cells transiently transfected with wild-type or mutant beta-catenin constructs and TCF-4 had no significant effect on beta-catenin/TCF-4 reporter activity or beta-catenin expression levels. In contrast, 2-25 microM EGCG inhibited beta-catenin/TCF-4 reporter activity in a concentration-dependent fashion and there was a concomitant reduction in beta-catenin protein levels in the cell lysates without changes in TCF-4 expression. The inhibition of reporter activity was recapitulated by white tea and green tea, each tested at a 25 microM EGCG equivalent concentration in the assay, and this was unaffected by the addition of exogenous catalase. The results indicate that physiologically relevant concentrations of tea and EGCG inhibit beta-catenin/TCF-4 reporter activity in HEK293 cells due to reduced expression of beta-catenin and that this is unlikely to be an artifact of H(2)O(2) generation under the assay conditions used here. These data are consistent with the findings from in vivo studies, showing the suppression of intestinal polyps by tea, via an apparent down-regulation of beta-catenin and Wnt target genes.

105. Int J Oncol. 2002 Sep;21(3):487-91.

Inhibition of fibroblast growth factors by green tea.

Sartippour MR, Heber D, Zhang L, Beatty P, Elashoff D, Elashoff R, Go VL, Brooks MN.

Department of Surgery, Division of Oncology, University of California-Los Angeles, Los Angeles, CA 90095, USA.

Investigators have shown that green tea may decrease the risk of cancer. It is widely accepted that the main active component of green tea is EGCG (epigallocatechin-3-gallate). In our previous study, we examined the effect of green tea on breast cancer growth and endothelial cells both in in vitro assays and in animal models. Our data show that both mixed green tea extract (GTE) as well as its individual catechin components are effective in inhibiting breast cancer and endothelial cell proliferation in vitro, and that GTE suppresses breast cancer xenograft size and decreases the tumor blood vessel density in vivo. In the present study, we further demonstrate that 40 microg/ml GTE or EGCG can decrease the levels of the angiogenic factor bFGF (basic fibroblast growth factor) levels in the cells. This phenomenon is observed in both human umbilical vein endothelial cells (HUVECs) and in human breast cancer cells MDA-MB231. This effect is dose dependent. Furthermore, GTE and EGCG decrease the transcript levels of bFGF and aFGF (acidic fibroblast growth factor) in HUVECs and MDA-MB231 cells. Our findings suggest that the inhibition of the angiogenic fibroblast growth factors could account for one of the mechanisms of green tea's actions. Since cancer is angiogenesis dependent, this may partially explain the antineoplastic effects associated with green tea consumption.

106. J Epidemiol. 2002 May;12(3):191-8.

Relationship between coffee and green tea consumption and all-cause mortality in a cohort of a rural Japanese population.

Iwai N, Ohshiro H, Kurozawa Y, Hosoda T, Morita H, Funakawa K, Okamoto M, Nose T.

Department of Public Health, Faculty of Medicine, Tottori University, Yonago, Japan.

We conducted a cohort study to investigate the effects of coffee and green tea consumption on all-cause mortality in a rural Japanese population. Data were obtained from 2,855 men and women aged 40-79 years in 1989, and during the subsequent 9.9 years of follow-up. Using the Cox regression model to adjust for potential confounding factors, we calculated the multivariate hazard ratios of death from all causes separately for men and women. The multivariate hazard ratio of mortality for men who consumed two or more cups of coffee per day, compared with those who consumed less than half a cup per day, was 0.43 (95% confidence interval, 0.30-0.63), and the ratio for those who consumed half to one cup of coffee per day was 0.70 (95% confidence interval, 0.52-0.94). Exclusion of subjects with less than 5 years of follow-up did not substantially change the findings. No other statistically significant associations were identified between consumption of the two beverages and all-cause mortality. For men, multivariate hazard ratios of death from apoplexy showed a significant inverse association with increasing coffee consumption. The effects of habitual coffee consumption and its related factors on health in Japan need to be studied in greater detail.

107. J Nutr. 2002 Aug;132(8):2307-11.

Green tea inhibits vascular endothelial growth factor (VEGF) induction in human breast cancer cells.

Sartippour MR, Shao ZM, Heber D, Beatty P, Zhang L, Liu C, Ellis L, Liu W, Go VL, Brooks MN.

Department of Surgery, Division of Oncology and. Center for Human Nutrition, University of California, Los Angeles 90095, USA.

Investigators have shown that green tea and its main catechin epigallocatechin-3 gallate (EGCG) may decrease the risk of cancer. Our previous study showed that green tea extract (GTE) as well as its individual catechin components inhibited MDA-MB231 breast cancer cell and human umbilical vein endothelial cell (HUVEC) proliferation. Further, GTE suppressed breast cancer xenograft size and decreased the tumor vessel density in vivo. In the current study, we investigated the effect of GTE on the major angiogenic factor vascular endothelial growth factor (VEGF) in an in vitro experiment. GTE or EGCG (40 mg/L) significantly decreased the levels of the VEGF peptide secreted into conditioned media. This occurred in both HUVEC and human breast cancer cells and the effect was dose dependent. Furthermore, GTE and EGCG decreased the RNA levels of VEGF in MDA-MB231 cells. This inhibition occurred at the transcriptional regulation level and was accompanied by a significant decrease in VEGF promoter activity. We also showed that GTE decreased c-fos and c-jun RNA transcripts, suggesting that activator protein (AP)-1-responsive regions present in the human VEGF promoter may be involved in the inhibitory effect of GTE. Furthermore, GTE suppressed the expression of protein kinase C, another VEGF transcription modulator, in breast cancer cells. Inhibition of VEGF transcription appeared to be one of the molecular mechanism(s) involved in the antiangiogenic effects of green tea, which may contribute to its potential use for breast cancer treatment and/or prevention.

108. Cytokine. 2002 Jun 7;18(5):266-73.

Green tea polyphenol blocks h(2)o(2)-induced interleukin-8 production from human alveolar epithelial cells.

Matsuoka K, Isowa N, Yoshimura T, Liu M, Wada H.

Department of Thoracic Surgery, Kyoto University, Japan.

Reactive oxygen species (ROS) play crucial roles in ischemia-reperfusion (IR) injury of lung transplants. Reactive oxygen species may stimulate the production of neutrophil chemotactic factors such as interleukin-8 (IL-8), from alveolar epithelial cells, causing recruitment and activation of neutrophils in the reperfused tissue. Green tea polyphenol has potent anti-oxidative activities and anti-inflammatory effects by decreasing cytokine production. In the present study, we found that green tea polyphenol significantly inhibited IL-8 production induced by hydrogen peroxide (H(2)O(2)) in human lung alveolar epithelial cells (A549 line). It has been shown that mitogen activated protein kinases, such as Jun N-terminal kinase (JNK), p38 and p44/42, could mediate IL-8 production from a variety of cell types. We further investigated the effect of green tea polyphenol on these protein kinases, and demonstrated that H(2)O(2)-induced phosphorylation of JNK and p38 but not p44/42 was inhibited by green tea polyphenol in A549 cells. We speculate that green tea polyphenol may inhibit H(2)O(2)-induced IL-8 production from A549 cells through inactivation of JNK and p38.

109. Prostaglandins Leukot Essent Fatty Acids. 2002 May-Jun;66(5-6):519-24.

Green tea extracts can counteract the modification of fatty acid composition induced by doxorubicin in cultured cardiomyocytes.

Hrelia S, Bordoni A, Angeloni C, Leoncini E, Toschi TG, Lercker G, Biagi PL.

Nutrition Research Center, Department of Biochemistry G. Moruzzi University of Bologna, Italy. hrelia@biocfarm.unibo.it

Doxorubicin cardiotoxicity is associated with the generation of free radicals, and involves not only lipid peroxidation but also a decreased biosynthesis of highly unsaturated fatty acids, leading to significant modification in cardiomyocyte fatty acid composition. We have evaluated whether naturally occurring antioxidants could counteract this side-effect. Green tea is an excellent source of catechins; we supplemented cultured rat cardiomyocytes with different green tea extracts to relate their catechin content and composition to their ability in protecting cells against doxorubicin-induced damage. The determination of total lipid fatty acid composition, of conjugated diene production (indicator of lipid peroxidation), and of lactate dehydrogenase release revealed that supplementation with tea extracts could counteract significant modifications in the fatty acyl pattern due to doxorubicin exposure, although to different extents. These differences could be ascribed to the different total catechin content and to qualitative differences among the tea extracts, determined by HPLC analysis.

110. Addict Biol. 2002 Jul;7(3):307-14.

Green tea as a potent antioxidant in alcohol intoxication.

Skrzydlewska E, Ostrowska J, Stankiewicz A, Farbiszewski R.

Department of Analytical Chemistry, Medical Academy of Bialystok, Bialystok, Poland. skrzydle@amb.ac.bialystok.pl

Ethanol oxidation to acetaldehyde and next to acetate is accompanied by free radical generation. Free radicals can affect cell integrity when antioxidant mechanisms are no longer able to cope with the free radical generation observed in ethanol intoxication. Natural antioxidants are particularly useful in such a situation. The present study was designed to investigate the efficacy of green tea as a source of water-soluble antioxidants (catechins) on the liver and blood serum antioxidative potential of rats chronically (28 days) intoxicated with ethanol. Alcohol caused a decrease in liver superoxide dismutase, glutathione peroxidase and catalase activities and an increase in activity of glutathione reductase. Moreover, a decrease in the level of reduced glutathione, ascorbic acid, vitamins A and E and beta-carotene were observed. The activity of serum glutathione peroxidase decreased while glutathione reductase activity increased. The level of serum non-enzymatic antioxidants was also decreased in the liver. Alcohol administration caused an increase in the liver and serum lipid peroxidation products, measured as thiobarbituric acid-reactive substances. However, green tea prevents the changes observed after ethanol intoxication. Green tea also protects membrane phospholipids from enhanced peroxidation. These results indicate a beneficial effect of green tea in alcohol intoxication.

111. J Biol Chem. 2002 Sep 20;277(38):34933-40. Epub 2002 Jul 12.

Epigallocatechin gallate, a constituent of green tea, represses hepatic glucose production.

Waltner-Law ME, Wang XL, Law BK, Hall RK, Nawano M, Granner DK.

Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0615, USA.

Herbs have been used for medicinal purposes, including the treatment of diabetes, for centuries. Plants containing flavonoids are used to treat diabetes in Indian medicine and the green tea flavonoid, epigallocatechin gallate (EGCG), is reported to have glucose-lowering effects in animals. We show here that the regulation of hepatic glucose production is decreased by EGCG. Furthermore, like insulin, EGCG increases tyrosine phosphorylation of the insulin receptor and insulin receptor substrate-1 (IRS-1), and it reduces phosphoenolpyruvate carboxykinase gene expression in a phosphoinositide 3-kinase-dependent manner. EGCG also mimics insulin by increasing phosphoinositide 3-kinase, mitogen-activated protein kinase, and p70(s6k) activity. EGCG differs from insulin, however, in that it affects several insulin-activated kinases with slower kinetics. Furthermore, EGCG regulates genes that encode gluconeogenic enzymes and protein-tyrosine phosphorylation by modulating the redox state of the cell. These results demonstrate that changes in the redox state may have beneficial effects for the treatment of diabetes and suggest a potential role for EGCG, or derivatives, as an antidiabetic agent.

112. Urol Clin North Am. 2002 Feb;29(1):49-57, viii.

Green tea and prostate cancer.

Gupta S, Mukhtar H.

Department of Urology, University Hospitals of Cleveland, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA.

Many laboratory studies and human epidemiological data suggest that most prostate cancer deaths are attributable to lifestyle, including nutritional factors where diet plays a major role in initiation as well as subsequent progression of the disease. Under these circumstances, chemoprevention seems to be a logical and obvious strategy. Because of its long latency and high incidence, prostate cancer is an ideal disease for chemoprevention. The suitable agent(s) for prostate cancer chemoprevention should be the one(s) that has efficacy in the laboratory experiments on one hand, and also possesses proven epidemiological basis on the other hand. In this article, we address the use of green tea for prostate cancer chemoprevention. Experimental as well as the epidemiological basis for this possibility is provided.

113. Nutr Cancer. 2001;41(1-2):119-25.

Green tea catechins and vitamin E inhibit angiogenesis of human microvascular endothelial cells through suppression of IL-8 production.

Tang FY, Meydani M.

Vascular Biology Laboratory, JM USDA-Human Nutrition Research Center on Aging at Tufts University, Boston, MA 02111, USA.

Epidemiological and animal studies have indicated that consumption of green tea and high vitamin E intake are associated with a reduced risk of developing certain forms of cancer. However, the inhibitory mechanism of green tea catechins and vitamin E in angiogenesis, an important process in tumor growth, has not been well established. In the present study, alpha-tocopherol and several major catechins of green tea (catechin, epicatechin, epicatechin gallate, epigallocatechin, and epigallocatechin gallate) were tested for their ability to inhibit tube formation in vitro using a model in which human microvascular endothelial cells were exposed to a constant rate of a physiologically low level of H2O2. In this model, the production of interleukin (IL)-8 by human microvascular endothelial cells at a low level of H2O2 was required for angiogenesis, as assessed by tube formation in three-dimensional gel in culture. Vitamin E (d-alpha-tocopherol, 40 microM) in the culture media significantly reduced IL-8 production and angiogenesis. Among the green tea catechins, epigallocatechin (0.5-1 microM) was the most effective in reducing IL-8 production and inhibiting angiogenesis. These results suggest that consumption of green tea catechins or supplemental intake of vitamin E may have preventive effects on tumor development, mediated, at least in part, through inhibition of angiogenesis via suppression of IL-8 production.

114. Food Chem Toxicol. 2002 Jul;40(7):949-57.

Volatile N-nitrosamine inhibition after intake Korean green tea and Maesil (Prunus mume SIEB. et ZACC.) extracts with an amine-rich diet in subjects ingesting nitrate.

Choi SY, Chung MJ, Sung NJ.

Department of Food and Nutrition, Gyeongsang National University, Jinju 660-701, South Korea.

The formation of carcinogenic nitrosamines under simulated gastric conditions was studied during the incubation of amine rich food and nitrate, and its possible inhibition by adding kumquat, sweet orange, strawberry, garlic, kale juices, Maesil (Prunus mume) and green tea extracts. The strawberry, kale juices, Maesil and green tea extracts were equally effective in reducing the formation of N-nitrosodimethylamine (NDMA). The fruits of P. mume SIEB. et ZACC. (Korean name, Maesil) have been used as a traditional drug and health food in Korea. During four weeks of test (designated EW1, EW2, EW3 and EW4; experiment week 1, 2, 3 and 4 diets) volunteers consumed a diet of low nitrate and amine (EW1) and consumed a fish meal rich in amines as nitrosatable precursors in combination with intake of nitrate-containing drinking water without (EW2) or with Maesil and green tea extracts (EW3 and EW4, respectively). The intake of nitrate-containing drinking water (340 mg nitrate/100 ml) resulted in a significant rise in mean salivary nitrate and nitrite concentrations and in mean urinary nitrate levels. Mean urinary nitrate was increased to 455.0+/-66.2, 334.6+/-67.8 and 333.4+/-50.7 mg/18 h after the nitrate intake of EW2, EW3 and EW4, respectively. Significant increases in urinary dimethylamine and trimethylamine levels were observed in consumption of diets (EW2, EW3, and EW4) rich in amine and nitrate. Maesil and green tea extract in EW3 and EW4 enhanced the increase of urinary dimethylamine and trimethylamine levels. Urinary excretion of N-nitrosodimethylamine in consumption of diet rich in nitrate and amine (EW2) increased to 6504.4+/-2638.7 ng/18 h from 257.0+/-112.0 ng/18 h of low nitrate and amine diet (EW1). Korean green tea and Maesil extracts in nitrate and amine rich diet reduced the excretion of N-nitrosodimethylamine to 249.7+/-90.6 and 752.7+/-595.3 ng/18 h, respectively, compared with 6504.4+/-2638.7 ng /18 h after ingestion of TD1 diet.

115. Food Chem Toxicol. 2002 Jul;40(7):925-33.

Inhibition of aromatase activity by green tea extract catechins and their endocrinological effects of oral administration in rats.

Satoh K, Sakamoto Y, Ogata A, Nagai F, Mikuriya H, Numazawa M, Yamada K, Aoki N.

Department of Toxicology, The Tokyo Metropolitan Research Laboratory of Public Health, 24-1 Hyakunincho 3 chome, Shinjuku-ku, Japan. sato@tokyo-eiken.go.jp

We orally administered polyphenone-60 (P-60), green tea extract catechins, in the diet (0, 1.25 and 5%) to male rats for 2, 4 and 8 weeks initiated at 5 weeks old. It was found that a 5% dose to male rats for 2-8 weeks induced goiters and decreased weights of the body, testis and prostate gland. Endocrinologically, elevating plasma thyroid stimulating hormone (TSH), luteinizing hormone (LH) and testosterone levels and decreasing tri-iodothyronine (T(3)) and thyroxine (T(4)) levels were induced by this treatment. We also found that P-60 as a whole and some of its constituents exhibited inhibitory effects on human placental aromatase activity by in vitro assay. The concentration of P-60 that required producing 50% inhibition of the aromatase activity (IC(50) value) was 28 microg/ml. The IC(50) values of (-)-catechin gallate (Cg), (-)-epigallocatechin (EGC), (-)-epigallocatechin gallate (EGCg) and (-)-gallocatechin gallate (GCg) were 5.5 x 10(-6), 1.0 x 10(-4), 6.0 x 10(-5) and 1.5 x 10(-5) M, respectively. (-)- Epicatechin gallate (ECg) at 1.0 x 10(-4) M produced 20% inhibition. (-)-Epicatechin (EC) and (+)-catechin (CT) exhibited no effects on aromatase activity. The endocrinological changes observed in vivo were in conformity with antithyroid effects and aromatase inhibition effects of P-60 and its constituents.

116. J Biol Chem. 2002 Aug 23;277(34):30574-80. Epub 2002 Jun 10.

Involvement of protein kinase C activation and cell survival/ cell cycle genes in green tea polyphenol (-)-epigallocatechin 3-gallate neuroprotective action.

Levites Y, Amit T, Youdim MB, Mandel S.

Eve Topf and USA National Parkinson Foundation Centers of Excellence for Neurodegenerative Diseases Research, Dept. of Pharmacology, Technion-Faculty of Medicine, 31096 Haifa, Israel.

Studies from our laboratory have demonstrated that the major green tea polyphenol, (-)-epigallocatechin 3-gallate (EGCG), exerts potent neuroprotective actions in the mice model of Parkinson's disease. These studies were extended to neuronal cell culture employing the parkinsonism-inducing neurotoxin, 6-hydroxydopamine (6-OHDA). Pretreatment with EGCG (0.1-10 microm) attenuated human neuroblastoma (NB) SH-SY5Y cell death, induced by a 24-h exposure to 6-OHDA (50 microm). Potential cell signaling candidates involved in this neuroprotective effect were further examined. EGCG restored the reduced protein kinase C (PKC) and extracellular signal-regulated kinases (ERK1/2) activities caused by 6-OHDA toxicity. However, the neuroprotective effect of EGCG on cell survival was abolished by pretreatment with PKC inhibitor GF 109203X (1 microm). Because EGCG increased phosphorylated PKC, we suggest that PKC isoenzymes are involved in the neuroprotective action of EGCG against 6-OHDA. In addition, gene expression analysis revealed that EGCG prevented both the 6-OHDA-induced expression of several mRNAs, such as Bax, Bad, and Mdm2, and the decrease in Bcl-2, Bcl-w, and Bcl-x(L). These results suggest that the neuroprotective mechanism of EGCG against oxidative stress-induced cell death includes stimulation of PKC and modulation of cell survival/cell cycle genes.

117. Arch Biochem Biophys. 2002 May 1;401(1):29-37.

Green tea constituent epigallocatechin-3-gallate inhibits angiogenic differentiation of human endothelial cells.

Singh AK, Seth P, Anthony P, Husain MM, Madhavan S, Mukhtar H, Maheshwari RK.

Center for Combat Casualty and Life Sustainment Research, Department of Pathology, Uniformed Services University of Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20852, USA.

Several independent research studies have shown that consumption of green tea reduces the development of cancer in many animal models. Epidemiological observations, though inconclusive, are suggesting that green tea consumption may also reduce the risk of some cancers in humans. These anti-carcinogenic effects of green tea have been attributed to its constituent polyphenols. Angiogenesis is a crucial step in the growth and metastasis of cancers. We have investigated the effect of the major polyphenolic constituent of green tea, epigallocatechin-3-gallate (EGCG), on the tube formation of human umbilical vein endothelial cells (HUVEC) on matrigel. Tube formation was inhibited by treatment both prior to plating and after plating endothelial cells on matrigel. EGCG treatment also was found to reduce the migration of endothelial cells in matrigel plug model. The role of matrix metalloproteinases (MMP) has been shown to play an important role during angiogenesis. Zymography was performed to determine if EGCG had any effect on MMPs. Zymographs of EGCG-treated culture supernatants modulated the gelatinolytic activities of secreted proteinases indicating that EGCG may be exerting its inhibitory effect by regulating proteinases. These findings suggest that EGCG acts as an angiogenesis inhibitor by modulating protease activity during endothelial morphogenesis. (c) 2002 Elsevier Science (USA).

118. Phytomedicine. 2002 Apr;9(3):232-8.

Protective effect of green tea against lipid peroxidation in the rat liver, blood serum and the brain.

Skrzydlewska E, Ostrowska J, Farbiszewski R, Michalak K.

Department of Analytical Chemistry, Medical Academy of Bialystok, Poland. skrzydle@solar.amb.edu.pl

This paper reports data on the effect of green tea on the lipid peroxidation products formation and parameters of antioxidative system of the liver, blood serum and central nervous tissue of healthy young rats drinking green tea for five weeks. The rats were permitted free access to solubilized extract of green tea. Bioactive ingredients of green tea extract caused in the liver an increase in the activity of glutathione peroxidase and glutathione reductase and in the content of reduced glutathione as well as marked decrease in lipid hydroperoxides (LOOH), 4-hydroksynonenal (4-HNE) and malondialdehyde (MDA). The concentration of vitamin A increased by about 40%. Minor changes in the measured parameters were observed in the blood serum. GSH content increased slightly, whereas the index of the total antioxidant status increased significantly. In contrast, the lipid peroxidation products, particularly MDA was significantly diminished. In the central nervous tissue the activity of superoxide dismutase and glutathione peroxidase decreased while the activity od glutathione reductase and catalase increased after drinking green tea. Moreover the level of LOOH, 4-HNE and MDA significantly decreased. The use of green tea extract appeared to be beneficial to rats in reducing lipid peroxidation products. These results support and substantiate traditional consumption of green tea as protection against lipid peroxidation in the liver, blood serum, and central nervous tissue.

119. J Nutr. 2002 Jun;132(6):1282-8.

Green tea extract inhibits the lymphatic absorption of cholesterol and alpha-tocopherol in ovariectomized rats.

Loest HB, Noh SK, Koo SI.

Department of Human Nutrition, Kansas State University, Manhattan, KS 66506, USA.

Evidence indicates that green tea consumption lowers the serum level of cholesterol (CH). This study was conducted to determine whether green tea lowers the intestinal absorption of CH and other lipids in ovariectomized (OX) rats. OX rats with lymph duct cannulae were infused at 3.0 mL/h for 8 h via an intraduodenal catheter with a lipid emulsion containing (14)C-cholesterol ((14)C-CH) and alpha-tocopherol (alphaTP) without (GT0) or with green tea extract standardized to 42.9 mg (GT1) or 120.5 mg (GT2) of total catechins in PBS (pH 6.5). Green tea extracts dose-dependently reduced (P < 0.05) the lymphatic absorption of (14)C-CH. The cumulative absorptions of (14)C-CH in rats infused with GT0, GT1 and GT2 were 36.3 +/- 1.1, 20.7 +/- 4.3 and 4.8 +/- 4.1% dose, respectively. The percentage distribution of esterified CH did not differ between rats infused with GT0 and GT1 (80.2 +/- 2.3% vs. 79.0 +/- 1.7%), but was significantly lower in those given GT2 (69.1 +/- 6.8%). The absorption of alphaTP also was significantly reduced by GT1 (736.5 +/- 204.9 nmol, 20.8 +/- 5.8% dose) and GT2 (281.0 +/- 190.8 nmol, 7.9 +/- 5.4% dose) compared with GT0 (1048.8 +/- 174.9 nmol, 29.6 +/- 4.9% dose). The absorption of fat was significantly increased by GT1 (862.6 +/- 151.1 micromol) but lowered by GT2 (557.9 +/- 252.2 micromol) relative to GT0 (717.7 +/- 39.1 micromol). The findings provide direct evidence that green tea has a profound inhibitory effect on the intestinal absorption of CH and alphaTP in OX rats. Whether the inhibitory effect of green tea extract is attributable to a specific catechin(s) and other components in green tea remains to be determined.

120. Biosci Biotechnol Biochem. 2002 Apr;66(4):711-6.

Effects of dietary powdered green tea and theanine on tumor growth and endogenous hyperlipidemia in hepatoma-bearing rats.

Zhang G, Miura Y, Yagasaki K.

Department of Applied Biological Science, Tokyo Noko University, Fuchu, Japan.

The effects of dietary powdered green tea (PGT) and theanine on in vivo hepatoma growth and cancerous hyperlipidemia were investigated in rats that had been implanted with a rat ascites hepatoma cell line of AH109A cells. The hepatoma-bearing rats were fed with a 20% casein diet (20C), 20C containing 2% PGT, or 20C containing 0.1% theanine for 14 days. Dietary PGT significantly and time-dependently reduced the solid tumor volume and weight as did dietary theanine. The hepatoma-induced endogenous hyperlipidemia, which was characterized by rises in the serum cholesterol (hypercholesterolemia) and triglyceride (hypertriglyceridemia) levels, was significantly suppressed by PGT and theanine supplementation. Bile acid excretion into the feces was significantly higher in the PGT- and theanine-fed rats than in the control rats. This inhibition of hypercholesterolemia may have resulted from tumor growth suppression as well as increased excretion of steroids from the body. These results suggest that PGT had both anti-proliferative activity toward hepatoma cells and hypolipidemic activity in the hepatoma bearing rats. They also suggest that theanine was, at least in part, responsible for the PGT actions.

121. J Agric Food Chem. 2002 Jun 5;50(12):3549-52.

Antioxidative activity of green tea polyphenol in cholesterol-fed rats.

Yokozawa T, Nakagawa T, Kitani K.

Institute of Natural Medicine, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama 930-0194, Japan. yokozawa@ms.toyoma-mpu.ac.jp

This study investigated the effects of green tea polyphenol on the serum antioxidative activity and cholesterol levels of cholesterol-fed rats and compared them with those of probucol, an antioxidant hypocholesterolemic agent. To evaluate the antioxidative activity, the susceptibility to oxidative modification of low-density lipoprotein (LDL) isolated from the serum of cholesterol-fed rats was measured, as was the serum antioxidative activity using the spontaneous autoxidation system of brain homogenate. Administration of green tea polyphenol effectively inhibited LDL oxidation and elevated serum antioxidative activity to the same degree as probucol. However, higher amounts of polyphenol than probucol needed to be administered to reduce the total, free, and LDL cholesterol levels. Furthermore, green tea polyphenol increased the levels of high-density lipoprotein (HDL) cholesterol, leading to dose-dependent improvement of the atherogenic index, an effect that was not seen with probucol. Thus, green tea polyphenol may exert an antiatherosclerotic action by virtue of its antioxidant properties and by increasing HDL cholesterol levels.

122. Biol Chem. 2002 Mar-Apr;383(3-4):663-70.

Green tea extract protects against early alcohol-induced liver injury in rats.

Arteel GE, Uesugi T, Bevan LN, Gabele E, Wheeler MD, McKim SE, Thurman RG.

Department of Pharmacology, University of North Carolina at Chapel Hill, 27599-7365, USA.

Oxidants have been shown to be involved in alcohol-induced liver injury. This study was designed to test the hypothesis that the antioxidant polyphenolic extract of green tea, comprised predominantly of epigallocatechin gallate, protects against early alcohol-induced liver injury in rats. Male Wistar rats were fed high-fat liquid diets with or without ethanol (10-14 g kg(-1) day(-1)) and green tea (300 mg kg(-1) day(-1)) continuously for 4 weeks using an intragastric enteral feeding protocol. Mean body weight gains (approximately 4 g/day) were not significantly different between treatment groups, and green tea extract did not the affect average concentration or the cycling of urine ethanol concentrations (0-550 mg dl(-1) day(-1)). After 4 weeks, serum ALT levels were increased significantly about 4-fold over control values (35+/-3 IU/l) by enteral ethanol (114+/-18); inclusion of green tea extract in the diet significantly blunted this increase (65+/-10). Enteral ethanol also caused severe fatty accumulation, mild inflammation, and necrosis in the liver. While not affecting fat accumulation or inflammation, green tea extract significantly blunted increases in necrosis caused by ethanol. Furthermore, ethanol significantly increased the accumulation of protein adducts of 4-hydroxynonenal, a product of lipid peroxidation and an index of oxidative stress; green tea extract blocked this effect almost completely. TNFalpha protein levels were increased in liver by alcohol; this phenomenon was also blunted by green tea extract. These results indicate that simple dietary antioxidants, such as those found in green tea, prevent early alcohol-induced liver injury, most likely by preventing oxidative stress.

123. Amino Acids. 2002;22(1):1-13.

Cancer therapy and prevention by green tea: role of ornithine decarboxylase.

Bachrach U, Wang YC.

Department of Molecular Biology, Hebrew University-Hadassah Medical School, Jerusalem, Israel. bachur@md2.huji.ac.il

Green tea which is widely consumed in China, Japan and India, contains polyphenolic compounds, which account for 30% of the dry weight of the leaves. Most of the polyphenols are flavanols, of which (-)-epigallocatechin-3-gallate (EGCG) is most abundant. Epidemiological studies revealed that the incidences of stomach and prostate cancers are the lowest in the world among a population that consumes green tea on a regular basis. It has also been reported that the quantity of green tea consumed, plays an important role in reducing cancer risk and in delaying cancer outbreak and recurrence. Various systems were used to confirm anti-cancer activities of green tea and/or EGCG. These included experimental animals in which cancer was induced chemically. Cultured cells transformed chemically or by oncogenes were also used. These studies clearly demonstrated that green tea or EGCG have anticancer and cancer preventive properties. The mechanisms of these activities have also been studied in details. It has been shown that green tea and its active components interfere with signal transduction pathways. Thus the activities of various protein kinases are inhibited, the expression of nuclear proto-oncogenes declines and the activity of ornithine decarboxylase (ODC) is reduced. ODC, which catalyzes the rate-limiting step in the biosynthesis of polyamines is closely linked with cellular proliferation and carcinogenesis. Inhibitors of ODC, like alpha-difluoromethylornithine (DFMO) have long been used for cancer prevention and therapy. It has been suggested that polyamine depletion by green tea could offer one explanation for its anti-cancer activities.

124. Biol Trace Elem Res. 2002 May;86(2):177-91.

Antimutagenic activity of selenium-enriched green tea toward the heterocyclic amine 2-amino-3-methylimidazo[4,5-f]quinoline.

Amantana A, Santana-Rios G, Butler JA, Xu M, Whanger PD, Dashwood RH.

Department of Envionmental and Molecular Toxicology, Oregon State University, Corvallis 97331, USA.

Both selenium and green tea have been reported to exhibit antigenotoxic and cancer chemopreventive properties. We compared the antimutagenic activities of regular green tea and selenium-enriched green tea obtained from Hubei Province, China, toward the heterocyclic amine, 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) in the Salmonella assay. Selenium-enriched green tea obtained by foliar application of selenite exhibited concentration-dependent inhibition of IQ-induced mutagenesis in the presence of rat liver S9 and was significantly more effective than regular green tea tested under the same conditions. Analytical studies revealed no major differences in the polyphenol or caffeine content between regular green tea and selenium-enriched green tea, but the latter tea contained approximately 60-fold higher concentrations of selenium compared with regular green tea. The only soluble form of selenium was identified as selenite. The antimutagenic effects of certain individual tea constituents, such as epicatechin gallate and catechin, were enhanced by the addition of selenite to the Salmonella assay. Sodium selenite, sodium selenate, seleno-DL-cysteine, seleno-L-methionine, and L-Se-methylselenocysteine were not antimutagenic toward IQ when tested alone, but augmented significantly the inhibitory potency of green tea. The results suggested an enhancing ("coantimutagenic") effect of selenium in combination with green tea in vitro, but in vivo studies are needed to assess whether there is a synergistic effect of tea and selenium to protect against heterocyclic amine-induced mutagenesis and carcinogenesis.

125. Gen Dent. 2002 Mar-Apr;50(2):140-6.

Chemoprevention of oral cancer by green tea.

Hsu SD, Singh BB, Lewis JB, Borke JL, Dickinson DP, Drake L, Caughman GB, Schuster GS.

Department of Oral Biology and Maxillofacial Pathology, School of Dentistry, Medical College of Georgia, Augusta, USA.

Green tea has been a popular beverage for many centuries. Only recently, however, has the anti-cancer power of green tea constituents been unveiled. Green tea polyphenols are found to induce apoptosis (programmed cell death) in many types of tumor cells, including oral cancer cells. However, mechanisms that enable normal cells to evade the apoptotic effect still are not understood. In this study, cell growth and invasion assays combined with apoptosis assays were used to examine the effects of green tea extracts, green tea polyphenols, and the most potent green tea polyphenol, (-)-epigallocatechin-3-gallate (EGCG), on normal human keratinocytes and oral carcinoma cells. The results showed that green tea and its constituents selectively induce apoptosis only in oral carcinoma cells, while EGCG was able to inhibit the growth and invasion of oral carcinoma cells. These differential responses to green tea and its constituents between normal and malignant cells were correlated with the induction of p57, a cell cycle regulator. These data suggest that the chemopreventive effects of green tea polyphenols may involve a p57 mediated survival pathway in normal epithelial cells, while oral carcinoma cells undergo an apoptotic pathway. Therefore, regular consumption of green tea could be beneficial in the prevention of oral cancer.

126. Wien Med Wochenschr. 2002;152(5-6):153-8.

[Cancer prevention with green tea: reality and wishful thinking]

[Article in German]

Bertram B, Bartsch H.

Abteilung fur Toxikologie und Krebsrisikofaktoren, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 280, D-69120 Heidelberg, Deutschland. b.bertram@dkfz.de

Different processing of the leaves of the tea plant Camellia sinensis yields green or black tea, the subject of numerous investigations on the preventive effects on chronic degenerative diseases. The tea polyphenols, in particular (-)-epigallocatechin gallate (EGCG) were found to account for most of the protective effects. Since the concentration of EGCG is 5 times higher in green than in black tea, it is assumed that green tea possesses a greater preventive potential. Protection against cancer and cardiovascular diseases are the most important biomedical effects. In experimental models the preventive activity of tea is well documented for tumors at many organ sites. In humans, tea was reported to be protective against tumors of the lung, the gastrointestinal tract and the liver. Tea polyphenols, especially EGCG, were shown to exert cancer-protective activity by the following mechanisms: they inhibit the metabolic activation of carcinogens and induce at the same time detoxifying enzymes. They inhibit signaling pathways controlling cell proliferation and tumor growth such as protein kinase C and the release of tumor necrose factor-alpha from cells. Tea polyphenols reactivate processes which are impaired in tumor cells, such as the programmed cell death and the tumorsuppressor gene p53. Finally, tea polyphenols can also block angiogenesis leading to a starvation of the tumor. By inactivation of proteolytic enzymes they inhibit the development of metastases. This short review summarizes relevant recent findings on the protective effects of green tea constituents.

127. Food Chem Toxicol. 2002 Jun;40(6):841-4.

Induction of UDP-glucuronosyltransferase 1 (UDP-GT1) gene complex by green tea in male F344 rats.

Embola CW, Sohn OS, Fiala ES, Weisburger JH.

Department of Pathology, New York Medical College, 10595, Valhalla 10595, USA.

Tea is one of the most frequently consumed beverages in the world, second only to water. Epidemiological studies have associated the consumption of green tea with a lower risk of several types of cancers, including stomach, oral cavity, esophagus, and lung. This paper deals with the mechanism of action of tea as an effective chemopreventive agent for toxic chemicals and especially carcinogens. UDP-glucuronosyltransferase (UDP-GT) activities towards p-nitrophenol were markedly increased (51.8% or 1.5-fold) in rats that consumed tea compared with the control animals on water. Induction of UDP-glucuronosyltransferase activity by tea may involve the UDP-GT1 (UGT1A) gene complex of the UDP-GT multigene family. Therefore, a major mechanism of tea as a chemopreventive agent is induction of the microsomal detoxification enzyme, UDP-glucuronosyltransferase.

128. Nutr Cancer. 2001;40(2):149-56.

Green tea and its catechins inhibit breast cancer xenografts.

Sartippour MR, Heber D, Ma J, Lu Q, Go VL, Nguyen M.

Department of Surgery, University of California, Los Angeles, CA 90095, USA.

Investigators have shown that green tea may decrease the risk of cancer. It is widely accepted that the main active component of green tea is epigallocatechin-3-gallate (EGCG). In this study, we examined the effect of green tea on breast cancer growth and endothelial cells in in vitro assays and in animal models. Furthermore, we compared the potency of the different catechin components of green tea extract (GTE), including EGCG. Our data showed that mixed GTE and its individual catechin components were effective in inhibiting breast cancer and endothelial cell proliferation. In mouse experiments, GTE suppressed xenograft size and decreased the tumor vessel density. Our results demonstrated the value of all catechins and argued for the use of a mixed GTE as a botanical dietary supplement, rather than purified EGCG, in future clinical trials.

129. Mol Cell Biochem. 2002 Jan;229(1-2):85-92.

Green tea catechins decrease apolipoprotein B-100 secretion from HepG2 cells.

Yee WL, Wang Q, Agdinaoay T, Dang K, Chang H, Grandinetti A, Franke AA, Theriault A.

Division of Medical Technology, University of Hawaii, Honolulu 96822, USA.

To understand the hypocholesterolemic activity of green tea, our in vitro studies screened the relative efficacy of two structurally distinct green tea catechins, epicatechin (EC) and epigallocatechin gallate (EGCG), on apolipoprotein B-100 (apoB) and lipid production using a well established human hepatoma cell-line, HepG2, as the model system. This study showed that HepG2 cells pretreated with EC and EGCG for 8 h exerted a dose-dependent inhibitory effect on apoB secretion. Total protein and albumin synthesis and secretion were unaffected indicating the effects on apoB secretion to be specific. Under lipid-rich conditions, apoB secretion was markedly reduced by EGCG and to a lesser extent by EC at 50 microM. Mechanistic study showed that tea catechins inhibited apoB secretion via a proteasome-independent pathway as indicated by a lack of response to N-acetyl-leucyl-leucyl-norleucinal (ALLN), a proteasome inhibitor. The effect on apoB secretion was also found to be independent of lipid biosynthesis. In summary, the data suggest that EGCG in contrast to EC is a potent inhibitor of apoB secretion. The results indicate that the gallate moiety in the catechin molecule may result in a beneficial effect on lipid metabolism in terms of apoB secretion.

130. Phytother Res. 2002 Mar;16 Suppl 1:S91-2.

Vitamin C is one of the lipolytic substances in green tea.

Hasegawa N, Niimi N, Odani F.

Department of Food and Nutrition, Nagoya Bunri College, 2-1 Sasazuka-cho, Nishi-ku, Nagoya 451-0077, Japan. hsgwn@nagoya-bunri.ac.jp

We have studied the influence of vitamin C contained in green tea on the lipolysis of well-differentiated 3T3-L1 cells. When mature adipocytes were exposed to vitamin C the triglyceride concentration was decreased (p < 0.05) and the activity of glycerophosphate dehydrogenase, a marker of adipose conversion, was significantly inhibited (p < 0.01). These data suggest that green tea may have a lipolytic activity due to the mechanism by which the vitamin C contained in it inhibits triglyceride accumulation. Copyright 2002 John Wiley & Sons, Ltd.

131. J Agric Food Chem. 2002 Apr 10;50(8):2418-22.

Protective activity of green tea against free radical- and glucose-mediated protein damage.

Nakagawa T, Yokozawa T, Terasawa K, Shu S, Juneja LR.

Institute of Natural Medicine, Toyama Medical and Pharmaceutical University, Sugitani, Toyama 930-0194, Japan.

Protein oxidation and glycation are posttranslational modifications that are implicated in the pathological development of many age-related disease processes. This study investigated the effects of green tea extract, and a green tea tannin mixture and its components, on protein damage induced by 2,2'-azobis(2-amidinopropane) dihydrochloride (a free radical generator) and glucose in in vitro assay systems. We found that green tea extract can effectively protect against protein damage, and showed that its action is mainly due to tannin. In addition, it was shown that the chemical structures of tannin components are also involved in this activity, suggesting that the presence of the gallate group at the 3 position plays the most important role in the protective activity against protein oxidation and glycation, and that there is also a contribution by the hydroxyl group at the 5' position in the B ring and the sterical structure. These findings demonstrate the mechanisms of the usefulness of green tea in protein oxidation- and glycation-associated diseases.

132. Biol Chem. 2002 Jan;383(1):101-5.

Anti-invasive effects of green tea polyphenol epigallocatechin-3-gallate (EGCG), a natural inhibitor of metallo and serine proteases.

Benelli R, Vene R, Bisacchi D, Garbisa S, Albini A.

Centro di Biotecnologie Avanzate,Genova, Italy.

Several reports have attributed to green tea chemopreventive and therapeutic properties. Epidemiological studies have linked the regular use of green tea to a reduced incidence of breast and colon carcinomas. Tea contains several antioxidants, including polyphenols of the catechin (green tea) and theaflavin (black tea) groups. Green tea derivatives have been shown to act in vitro and in vivo as anti-inflammatory, anti-viral and anti-tumor drugs. Despite the extensive body of data only few studies have investigated the molecular mechanisms underlying these effects. In this brief review we focus on the inhibitory activity of catechins derived from green tea toward proteases involved in tumor invasion.

133. Phytomedicine. 2002 Jan;9(1):3-8.

Recent findings of green tea extract AR25 (Exolise) and its activity for the treatment of obesity.

Chantre P, Lairon D.

Laboratoires Arkopharma, Carros, France. r-d@arkopharma.com

The green tea extract AR25 is an 80% ethanolic dry extract standardized at 25% catechins expressed as epigallocatechin gallate (EGCG). In vitro, green tea extract AR25 exerts a direct inhibition of gastric and pancreatic lipases and a stimulation of thermogenesis. In an open study, the effects of extract AR25 were evaluated in moderately obese patients. After 3 months, body weight was decreased by 4.6% and waist circumference by 4.48%. These results suggest the green tea extract AR25 to be a natural product for the treatment of obesity, which exerts its activity by several ways: inhibition of lipases and stimulation of thermogenesis.

134. AIDS. 2002 Apr 12;16(6):939-41.

Polyphenolic antioxidant (-)-epigallocatechin-3-gallate from green tea as a candidate anti-HIV agent.

Fassina G, Buffa A, Benelli R, Varnier OE, Noonan DM, Albini A.

Instituto Nazionale per la Ricerca sul Cancro, Genoa, Italy.

Epigallocatechin-3-gallate (EGCG), one of the components of green tea, has been suggested to have antiviral activity. To determine the effects of EGCG on HIV infection, peripheral blood lymphocytes were incubated with either LAI/IIIB or Bal HIV strains and increasing concentrations of EGCG. EGCG strongly inhibited the replication of both virus strains as determined by reverse transcriptase and p24 assays on the cell supernatants.

135. Am J Clin Nutr. 2002 Apr;75(4):749-53.

Green tea extract decreases muscle necrosis in mdx mice and protects against reactive oxygen species.

Buetler TM, Renard M, Offord EA, Schneider H, Ruegg UT.

Pharmacology Group, School of Pharmacy, University of Lausanne, Switzerland.

BACKGROUND: Duchenne muscular dystrophy is a severe X-linked congenital disorder characterized by lethal muscle wasting caused by the absence of the structural protein dystrophin. OBJECTIVE: Because generation of reactive oxygen species appears to play an important role in the pathogenesis of this disease, we tested whether antioxidant green tea extract could diminish muscle necrosis in the mdx mouse dystrophy model. DESIGN: A diet supplemented with 0.01% or 0.05% green tea extract was fed to dams and neonates for 4 wk beginning on the day of birth. Muscle necrosis and regeneration were determined in stained cryosections of soleus and elongator digitorum longus muscles. Radical scavenging by green tea extract was determined in differentiated cultured C2C12 cells treated with tert-butylhydroperoxide, with the use of 2',7'-dichlorofluorescin diacetate as a radical detector. RESULTS: This feeding regimen significantly and dose-dependently reduced necrosis in the fast-twitch muscle elongator digitorum longus but at the doses tested had no effect on the slow-twitch soleus muscle. Green tea extract concentration-dependently decreased oxidative stress induced by tert-butylhydroperoxide treatment of cultured mouse C2C12 myotubes. The lower effective dose tested in mdx mice corresponds to approximately equal to 1.4 L (7 cups) green tea/d in humans. CONCLUSION: Green tea extract may improve muscle health by reducing or delaying necrosis in mdx mice by an antioxidant mechanism.

136. Anticancer Res. 2001 Nov-Dec;21(6A):3743-8.

Chemopreventive effects of green tea polyphenols correlate with reversible induction of p57 expression.

Hsu S, Lewis JB, Borke JL, Singh B, Dickinson DP, Caughman GB, Athar M, Drake L, Aiken AC, Huynh CT, Das BR, Osaki T, Schuster GS.

Department of Oral Biology and Maxillofacial Pathology, School of Dentistry, Medical College of Georgia, Augusta 30912-1126, USA. shsu@mail.mcg.edu

Green tea polyphenols are known to induce apoptosis in certain types of tumor cells. However, the mechanism(s) that enables normal cells to evade the apoptotic effect is still not understood. In this study, Western blot analysis combined with cycloheximide treatment was used to examine the effects of green tea polyphenols on the expression levels of p57, a cyclin-dependent kinase and apoptosis inhibitor, in normal human keratinocytes and in the oral carcinoma cell lines SCC25 and OSC2. The results showed that the most potent green tea polyphenol, (-)-epigallocatechin-3-gallate (EGCG), induced p57 in normal keratinocytes in a dosage- and time-dependent manner, while the levels of p57 protein in oral carcinoma cells were unaltered. The differential response in p57 induction was consistent with the apoptosis status detected by annexin V assay. The data suggest that the chemopreventive effects of green tea polyphenols may involve p57-mediated cell cycle regulation in normal epithelial cells.

137. Ann Epidemiol. 2002 Apr;12(3):157-65.

Green tea consumption and serum lipids and lipoproteins in a population of healthy workers in Japan.

Tokunaga S, White IR, Frost C, Tanaka K, Kono S, Tokudome S, Akamatsu T, Moriyama T, Zakouji H.

Department of Preventive Medicine, Graduate School of Medical School of Medical Sciences, Kyushu University, Fukuoka, Japan. Toksan@phealth.med.kyushu-u.ac.jp

PURPOSE: To examine the relation between green tea consumption and serum lipids and lipoproteins. METHODS: The subjects were 13,916 workers (8476 men and 5440 women) aged 40-69 years at over 1000 workplaces in Nagano prefecture, central Japan. They underwent health screening offered by a single medical institute between April 1995 and March 1996 and did not have morbid conditions affecting serum cholesterol levels. Serum concentrations of total cholesterol, high-density lipoprotein (HDL) cholesterol and triglycerides were measured at the screening. The consumption of green tea and other life-style characteristics were ascertained by a questionnaire. The data were analyzed with multivariate linear model. RESULTS: Daily consumption of green tea was reported by 86.7% of subjects. Green tea consumption was, statistically, significantly associated with lower levels of serum total cholesterol in both men and women while its associations with serum triglycerides and HDL cholesterol were not statistically significant. The inverse association of serum total cholesterol with green tea consumption appeared to level off at the consumption of more than 10 cups/day. Excluding the outlying subjects drinking more than 10 cups/day (0.4%), the regression analysis adjusting for age, body mass index, ethanol intake, smoking habit, coffee intake, and type of work showed that daily consumption of one cup of green tea was associated with a reduction in serum total cholesterol by 0.015 mmol/L (95% confidence interval 0.006 to 0.024, p < 0.001) in men and 0.015 mmol/L (0.004 to 0.025, p < 0.01) in women. After additional adjustment for selected dietary factors, the inverse association remained statistically significant; one cup of green tea per day was associated with a reduction in serum total cholesterol by 0.010 mmol/L (0.001 to 0.019, p = 0.03) in men and 0.012 mmol/L (0.001 to 0.022, p = 0.03) in women. CONCLUSION: Consumption of green tea was associated with lower serum concentration of total cholesterol in Japanese healthy workers age 40-69 years; however, green tea consumption was unrelated to serum HDL-cholesterol and triglycerides.

138. J Nutr. 2002 Mar;132(3):341-6.

Catechins from green tea (Camellia sinensis) inhibit bovine and human cartilage proteoglycan and type II collagen degradation in vitro.

Adcocks C, Collin P, Buttle DJ.

Division of Genomic Medicine, University of Sheffield Medical School, Sheffield S10 2RX, UK.

Polyphenolic compounds from green tea have been shown to reduce inflammation in a murine model of inflammatory arthritis, but no studies have been undertaken to investigate whether these compounds are protective to joint tissues. We therefore investigated the effects of catechins found in green tea on cartilage extracellular matrix components using in vitro model systems. Bovine nasal and metacarpophalangeal cartilage as well as human nondiseased, osteoarthritic and rheumatoid cartilage were cultured with and without reagents known to accelerate cartilage matrix breakdown. Individual catechins were added to the cultures and the amount of released proteoglycan and type II collagen was measured by metachromatic assay and inhibition ELISA, respectively. Possible nonspecific or toxic effects of the catechins were assessed by lactate output and proteoglycan synthesis. Catechins, particularly those containing a gallate ester, were effective at micromolar concentrations at inhibiting proteoglycan and type II collagen breakdown. No toxic effects of the catechins were evident. We conclude that some green tea catechins are chondroprotective and that consumption of green tea may be prophylactic for arthritis and may benefit the arthritis patient by reducing inflammation and slowing cartilage breakdown. Further studies will be required to determine whether these compounds access the joint space in sufficient concentration and in a form capable of providing efficacy in vivo.

139. Biochim Biophys Acta. 2002 Jan 30;1542(1-3):209-20.

Green tea polyphenol (-)-epigallocatechin 3-gallate inhibits MMP-2 secretion and MT1-MMP-driven migration in glioblastoma cells.

Annabi B, Lachambre MP, Bousquet-Gagnon N, Page M, Gingras D, Beliveau R.

Centre de Cancerologie Charles-Bruneau, Hopital Ste-Justine et Universite du Quebec a Montreal, C.P. 8888, Succ. Centre-ville, H3C 3P8, Montreal, QC, Canada.

We have recently shown that green tea polyphenols, and especially (-)-epigallocatechin 3-gallate (EGCg), acted as potent inhibitors of matrix metalloproteinase activities as well as of proMMP-2 activation (M. Demeule, M. Brossard, M. Page, D. Gingras, R. Beliveau, Biochim. Biophys. Acta 1478 (2000)). In the present work, we sought to examine the involvement of MT1-MMP in the EGCg-induced inhibition of proMMP-2 activation. The incubation of U-87 glioblastoma cells in the presence of concanavalin A or cytochalasin D, two potent activators of MT1-MMP, resulted in proMMP-2 activation that was correlated with the cell surface proteolytic processing of MT1-MMP to its inactive 43 kDa form. Addition of EGCg strongly inhibited the MT1-MMP-dependent proMMP-2 activation. The inhibitory effect of EGCg on MT1-MMP was also demonstrated by the down-regulation of MT1-MMP transcript levels and by the inhibition of MT1-MMP-driven cell migration of transfected COS-7 cells. These observations suggest that this catechin may act at both the MT1-MMP gene and protein expression levels. In addition, treatment of cells with non-cytotoxic doses of EGCg significantly reduced the amount of secreted proMMP-2, and led to a concomitant increase in intracellular levels of that protein. This effect was similar to that observed using well-characterized secretion inhibitors such as brefeldin A and manumycin, suggesting that EGCg could also potentially act on intracellular secretory pathways. Taken together, these results indicate that EGCg targets multiple MMP-mediated cellular events in cancer cells and provides a new mechanism for the anticancer properties of that molecule.

140. Biochim Biophys Acta. 2002 Jan 30;1542(1-3):149-59.

Inhibition of the multidrug resistance P-glycoprotein activity by green tea polyphenols.

Jodoin J, Demeule M, Beliveau R.

Laboratoire de Medecine Moleculaire, Centre de Cancerologie Charles Bruneau, Universite du Quebec a Montreal, Canada.

Many beneficial proprieties have been associated with polyphenols from green tea, such as chemopreventive, anticarcinogenic, antiatherogenic and antioxidant actions. In this study, we investigated the effects of green tea polyphenols (GTPs) and their principal catechins on the function of P-glycoprotein (P-gp), which is involved in the multidrug resistance phenotype of cancer cells. GTPs (30 microg/ml) inhibit the photolabeling of P-gp by 75% and increase the accumulation of rhodamine-123 (R-123) 3-fold in the multidrug-resistant cell line CH(R)C5, indicating that GTPs interact with P-gp and inhibit its transport activity. Moreover, the modulation of P-gp transport by GTPs was a reversible process. Among the catechins present in GTPs, EGCG, ECG and CG are responsible for inhibiting P-gp. In addition, EGCG potentiates the cytotoxicity of vinblastine (VBL) in CH(R)C5 cells. The inhibitory effect of EGCG on P-gp was also observed in human Caco-2 cells, which form an intestinal epithelial-like monolayer. Our results indicate that, in addition to their anti-cancer properties, GTPs and more particularly EGCG inhibit the binding and efflux of drugs by P-gp. Thus, GTPs or EGCG might be potential agents for modulating the bioavailability of P-gp substrates at the intestine and the multidrug resistance phenotype associated with expression of this transporter in cancer cells.

141. Int J Exp Pathol. 2001 Dec;82(6):309-16.

Inhibition of tumour invasion and angiogenesis by epigallocatechin gallate (EGCG), a major component of green tea.

Jung YD, Ellis LM.

Chonnam University Research Institute of Medical Sciences, Chonnam National University Medical School, Kwangju, Korea.

Epidemiological studies have suggested that consumption of green tea may decrease cancer risk. In addition, abundant pre-clinical data from several laboratories have provided convincing evidence that polyphenols present in green tea afford protection against cancer in both in vivo and in vitro studies. Recently, epigallocatechin gallate (EGCG), a putative chemopreventive agent and a major component of green tea, was reported to inhibit tumour invasion and angiogenesis, processes that are essential for tumour growth and metastasis. Understanding the basic principles by which EGCG inhibits tumour invasion and angiogenesis may lead to the development of new therapeutic strategies, in addition to supporting the role of green tea as a cancer chemopreventive agent.

142. Arch Biochem Biophys. 2002 Jan 15;397(2):424-9.

Effect of drinking green tea on age-associated accumulation of Maillard-type fluorescence and carbonyl groups in rat aortic and skin collagen.

Song DU, Jung YD, Chay KO, Chung MA, Lee KH, Yang SY, Shin BA, Ahn BW.

Chonnam National University Research Institute of Medical Sciences, Hakdong 5, Donggu, Kwangju 501-746, Korea.

Tea catechins and other flavonoids have been shown to potentially protect against chronic cardiovascular diseases such as coronary heart disease and atherosclerosis. In this study, 6-month-old female Sprague-Dawley rats were fed green tea extract (50 mg/100 ml in drinking water) up to the age of 22 months, and the age-associated changes in Maillard-type fluorescence and carbonyl groups in the aortic and skin collagen were compared with those occurring in the water-fed control animals. Collagen-linked Maillard-type fluorescence was found to increase in both the aortic and skin tissues as animals aged. The age-associated increase in the fluorescence in the aortic collagen was remarkably inhibited by the green tea extract treatment, while that occurring in the skin collagen was not significantly inhibited by the treatment. The collagen carbonyl content also increased in both the aortic and skin tissues as animals aged. In contrast with the case of Maillard-type fluorescence, however, the age-associated increase in the carbonyl content was not inhibited by the green tea extract treatment either in the aortic or skin collagen. These results suggest that the inhibition of AGE formation in collagen is an important mechanism for the protective effects of tea catechins against cardiovascular diseases. (c)2002 Elsevier Science.

143. J Nutr Biochem. 2002 Feb;13(2):103-111.

Green tea protection of hypoxia/reoxygenation injury in cultured cardiac cells.

Bordoni A, Hrelia S, Angeloni C, Giordano E, Guarnieri C, Caldarera CM, Biagi PL.

Centro Ricerche sulla Nutrizione, Dipartimento di Biochimica "G.Moruzzi", Universita' di Bologna, via Irnerio-48, 40126, Bologna, Italy

Antioxidant-rich diets exert a protective effect in diseases involving oxidative damage. Among dietary components, green tea is an excellent source of antioxidants. In this study, cultured neonatal rat cardiomyocytes were used to clarify the protective effect of a green tea extract on cell damage and lipid peroxidation induced by different periods of hypoxia followed by reoxigenation. Cultures of neonatal rat cardiomyocytes were exposed to 2--8 hr hypoxia, eventually followed by reoxygenation, in the absence or presence of alpha-tocopherol or green tea. LDH release and the production of conjugated diene lipids were measured, and appeared linearly related to the duration of hypoxia. During hypoxia, both LDH release and conjugated diene production were reduced by alpha-tocopherol and, in a dose dependent manner, by green tea, the 50 &mgr;g/ml being the most effective dose. Reoxygenation caused no further increase in LDH leakage, while it caused a significant increase in conjugate dienes, which absolute value was lower in antioxidant supplemented cells. Anyway, the ratio between conjugated diene production after hypoxia and after reoxygenation was similar in all groups, indicating that the severity of free radical-induced reoxygenation injury is proportional to the severity of previous hypoxic injury. Since hypoxic damage is reduced by alpha-tocopherol and green tea, our data suggest that any nutritional intervention to attenuate reoxygenation injury must be directed toward the attenuation of the hypoxic injury. Therefore, recommendations about a high dietary intake of antioxidants may be useful not only in the prevention, but also in the reduction of cardiac injury following ischemia.

144. J Nutr Biochem. 2002 Feb;13(2):96-102.

Green tea flavonoids inhibit the LDL oxidation in osteogenic disordered rats fed a marginal ascorbic acid in diet.

Kasaoka S, Hase K, Morita T, Kiriyama S.

Department of Health and Nutrition, Bunkyo University Women's College, 1100 Namegaya, Chigasaki, 253-8550, Kanagawa, Japan

Osteogenic Disorder Shionogi (ODS) rats can not synthesize ascorbic acid (AA). We have examined the capacity of green tea flavonoids (GTF) to modify low-density lipoprotein (LDL) oxidation in ODS rats with dietary AA restriction. In the first experiment, ODS rats were fed diets containing 300 (AA300 diet) or 0 (AA0 diet) mg AA/kg diets for 20 d. In comparison with the AA300 diet, the AA0 diet significantly decreased the concentrations of plasma AA and alpha-tocopherol in LDL and significantly shortened the lag time of LDL oxidation in vitro. In the second experiment, ODS rats were fed one of the following three diets: the AA300 diet, the diet containing 25 mg AA (AA25, marginal AA)/kg diet (AA25 diet), or the diet containing 25 mg AA + 8 g GTF/kg diet (AA25 + GTF diet) for 20 d. Plasma AA concentration were significantly lower in rats fed AA25 compared with AA300 but not in those fed AA25 + GTF. LDL oxidation lag time was significantly longer in rats fed AA25 + GTF compared with the other two groups. Lag time for LDL oxidation was significantly and positively correlated with LDL alpha-tocopherol (r = 0.6885, P = 0.0191). These results suggest that dietary flavonoids suppress the LDL oxidation through the sparing effect on LDL alpha-tocopherol and/or plasma AA when AA intake is marginal in the ODS rats.

145. Cancer Res. 2002 Feb 1;62(3):652-5.

Green tea polyphenol epigallocatechin-3 gallate inhibits Her-2/neu signaling, proliferation, and transformed phenotype of breast cancer cells.

Pianetti S, Guo S, Kavanagh KT, Sonenshein GE.

Department of Biochemistry, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118-2394, USA.

Overexpression of the epidermal growth factor receptor family member Her-2/neu in breast cancer is associated with poor prognosis. With evidence accumulating for a chemopreventive role of green tea polyphenols, the effects of epigallocatechin-3 gallate (EGCG) on Her-2/neu-overexpressing breast cancer cells were examined. EGCG inhibited mouse mammary tumor virus (MMTV)-Her-2/neu NF639 cell growth in culture and soft agar. EGCG reduced signaling via the phosphatidylinositol 3- kinase, Akt kinase to NF-kappaB pathway because of inhibition of basal Her-2/neu receptor tyrosine phosphorylation. EGCG similarly inhibited basal receptor phosphorylation in SMF and Ba/F3 2 + 4 cells, which suggests the potential beneficial use of EGCG in adjuvant therapy of tumors with Her-2/neu overexpression.

146. World J Gastroenterol. 1998 Feb;4(1):29.

Effect of garlic and garlic-green tea mixture on serum lipids in MNNG-induced experimental gastric carcinoma and precancerous lesion.

Su Q, Luo ZY, Teng H, Yun WD, Li YQ, He XE.

Institute of Oncology,Hengyang Medical College,Hengyang 421001,Hunan Province,China.

INTRODUCTION:To study effect of garlic and garlic-green tea mixture on serum contents of Tch,LDL and HDL in MNNG induced gastric carcinoma (GC) and precancerous lesion (PL) in Wistar rats.METHODS:Serum contents of Tch,LDL and HDL in normal control group (n=10,NG),MNNG group (n=30,MG),prevention group (n=30,PG),treatment group I (n=20,TG I) and treatment group II(n=20,TG II) were detected by PGE 6000/COD.RESULTS:Serum Tch and LDL of rats of MG (6.86+/-1.39 3.72+/-1.10) and its GC(6.95+/-1.37 3.77+/-1.08) and PL(6.42+/-1.04 3.56+/-0.74) were lower than that of NG (8.74+/-1.89 5.89+/-1.61) PG(7.73+/-3.18 4.96+/-2.89) and its GC(8.36+/-3.41 5.93+/-3.31) and PL(7.45+/-3.16 4.55+/-2.71),TGI(8.86+/-1.75 5.38+/-1.76) and its GC (9.10+/-2.27 5.55+/-2.51) and PL (8.61+/-1.17 5.22+/-0.55) and TG II (8.16+/-0.76 5.32+/-0.72) and its GC(8.52+/-0.67 5.96+/-0.48) and PL (8.02+/-0.79 5.09+/-0.65),respectively (P <0.01-0.05).Serum HDL of MG rats (2.76+/-0.48) and its GC(2.79+/-0.48) were remarkably higher than that of MG (2.20+/-0.85) and GC of PG (2.24+/-0.38) (P <0.05).CONCLUSION:Experimental gastric carcinoma and precancerous lesion were associated with hypocholesterolaemia,LDL and HDL.Garlic and garlic-green tea mixture can inhibit and reverse MNNG-induced gastric carcinoma and precancerous lesion in Wistar rats.

147. Arch Biochem Biophys. 2002 Feb 1;398(1):125-31.

Role of the retinoblastoma (pRb)-E2F/DP pathway in cancer chemopreventive effects of green tea polyphenol epigallocatechin-3-gallate.

Ahmad N, Adhami VM, Gupta S, Cheng P, Mukhtar H.

Department of Dermatology, Case Western Reserve University, The Research Institute of University Hospitals of Cleveland, 11100 Euclid Avenue, Cleveland, Ohio 44106, USA.

Because of the demonstrated role of green tea polyphenol epigallocatechin-3-gallate (EGCG) in cancer chemoprevention, there is considerable emphasis in understanding its mechanism of action. In this study, we assessed the involvement of the retinoblastoma (pRb)-E2F/DP pathway as an important contributor in the antiproliferative effects of EGCG. As shown by immunoblot analysis, EGCG treatment of A431 cells resulted in a dose- as well as time-dependent decrease in the total pRb with a relative increase in the hypophosphorylated form of pRb. EGCG also resulted in serine-780 phosphorylation of pRb in these cells. Further, EGCG was found to downregulate the protein expression of other members of the pRb family, viz. p130 and p107, in a dose- as well as time-dependent manner. This response was accompanied by downregulation in the protein expression of the E2F (1 through 5) family of transcription factors and their heterodimeric partners DP1 and DP2. Taken together, our study suggests that EGCG causes a downregulation of hyperphosphorylated pRb protein with a relative increase in hypophosphorylated pRb that, in turn, compromises with the availability of "free" E2F. This series of events leads to stoppage of cell cycle progression at the G1-->S phase transition thereby causing G0/G1 arrest and subsequent apoptotic cell death. This, to our knowledge, is the first study showing the involvement of the pRb-E2F/DP pathway in antiproliferative and apoptotic effects of EGCG.

148. Life Sci. 2001 Dec 21;70(5):603-14.

The green tea polyphenol (-)-epigallocatechin gallate attenuates beta-amyloid-induced neurotoxicity in cultured hippocampal neurons.

Choi YT, Jung CH, Lee SR, Bae JH, Baek WK, Suh MH, Park J, Park CW, Suh SI.

Department of Psychiatry, Keimyung University School of Medicine, Taegu, Korea.

Previous evidence has indicated that the neuronal toxicity of amyloid beta (betaA) protein is mediated through oxygen free radicals and can be attenuated by antioxidants and free radical scavengers. Recent studies have shown that green tea polyphenols reduced free radical-induced lipid peroxidation. The purpose of this study was to investigate whether (-)-epigallocatechin gallate (EGCG) would prevent or reduce the death of cultured hippocampal neuronal cells exposed to betaA because EGCG has a potent antioxidant property as a green tea polyphenol. Following exposure of the hippocampal neuronal cells to betaA for 48 hours, a marked hippocampal neuronal injuries and increases in malondialdehyde (MDA) level and caspase activity were observed. Co-treatment of cells with EGCG to betaA exposure elevated the cell survival and decreased the levels of MDA and caspase activity. Proapoptotic (p53 and Bax), Bcl-XL and cyclooxygenase (COX) proteins have been implicated in betaA-induced neuronal death. However, in this study the protective effects of EGCG seem to be independent of the regulation of p53, Bax, Bcl-XL and COX proteins. Taken together, the results suggest that EGCG has protective effects against betaA-induced neuronal apoptosis through scavenging reactive oxygen species, which may be beneficial for the prevention of Alzheimer's disease.

149. Cancer Res. 2002 Jan 15;62(2):381-5.

Green tea catechins inhibit vascular endothelial growth factor receptor phosphorylation.

Lamy S, Gingras D, Beliveau R.

Laboratoire de Medecine Moleculaire, Centre de Cancerologie Charles-Bruneau, Hopital Ste-Justine et Universite du Quebec a Montreal, Montreal, Quebec H3C 3P8, Canada.

Vascular endothelial growth factor (VEGF) receptors (VEGFR) play a major role in tumor angiogenesis and, thus, represent attractive targets for the development of novel anticancer therapeutics. In this work, we report that green tea catechins are novel inhibitors of VEGFR-2 activity. Physiological concentrations (0.01-1 microM) of epigallocatechin-3 gallate, catechin-3 gallate, and, to a lesser extent, epicatechin-3 gallate induce a rapid and potent inhibition of VEGF-dependent tyrosine phosphorylation of VEGFR-2. The inhibition of VEGFR-2 by epigallocatechin-3 gallate was similar to that induced by Semaxanib (SU5416), a specific VEGFR-2 inhibitor. The inhibition of VEGFR-2 activity by the catechins displayed positive correlation with the suppression of in vitro angiogenesis. These observations suggest that the anticancer properties of green tea extracts may be related to their inhibition of VEGF-dependent angiogenesis.

150. J Photochem Photobiol B. 2001 Dec 31;65(2-3):109-14.

Green tea polyphenols: DNA photodamage and photoimmunology.

Katiyar SK, Bergamo BM, Vyalil PK, Elmets CA.

Department of Dermatology, School of Medicine, University of Alabama at Birmingham, 1670 University Blvd., VH501, Box 202, Birmingham, AL 35294, USA. skatiyar@uab.edu

Green tea is a popular beverage consumed worldwide. The epicatechin derivatives, which are commonly called 'polyphenols', are the active ingredients in green tea and possess antioxidant, anti-inflammatory and anti-carcinogenic properties. Studies conducted by our group on human skin have demonstrated that green tea polyphenols (GTP) prevent ultraviolet (UV)-B-induced cyclobutane pyrimidine dimers (CPD), which are considered to be mediators of UVB-induced immune suppression and skin cancer induction. GTP treated human skin prevented penetration of UV radiation, which was demonstrated by the absence of immunostaining for CPD in the reticular dermis. The topical application of GTP or its most potent chemopreventive constituent (-)-epigallocatechin-3-gallate (EGCG) prior to exposure to UVB protects against UVB-induced local as well as systemic immune suppression in laboratory animals. Additionally, studies have shown that EGCG treatment of mouse skin inhibits UVB-induced infiltration of CD11b+ cells. CD11b is a cell surface marker for activated macrophages and neutrophils, which are associated with induction of UVB-induced suppression of contact hypersensitivity responses. EGCG treatment also results in reduction of the UVB-induced immunoregulatory cytokine interleukin (IL)-10 in skin as well as in draining lymph nodes, and an elevated amount of IL-12 in draining lymph nodes. These in vivo observations suggest that GTPs are photoprotective, and can be used as pharmacological agents for the prevention of solar UVB light-induced skin disorders associated with immune suppression and DNA damage.

151. Arch Toxicol. 2001 Dec;75(10):591-6.

Goitrogenic effects of green tea extract catechins by dietary administration in rats.

Sakamoto Y, Mikuriya H, Tayama K, Takahashi H, Nagasawa A, Yano N, Yuzawa K, Ogata A, Aoki N.

Department of Toxicology, Tokyo Metropolitan Research Laboratory of Public Health, Japan. sakamoto@tokyo-eiken.go.jp

The effects of green tea extract catechins on the rat thyroid were examined in a 13-week feeding study and subsequent 2-,4- and 8-week studies. Commercially available polyphenon-60 (P-60) which contains green tea extract catechins at 66.2% was used as a source of catechins. A basic diet containing different concentrations of P-60 was used for experiments. In the 13-week study, 10 rats of each sex were administered diets containing P-60 at 0 (control), 0.625, 1.25, 2.5 and 5.0%. Goiters were observed in the 13-week test. The mean thyroid weight of rats fed a diet containing 5.0% of P-60 (5.0% group) significantly increased to 444% of the control in males and to 304% of the control in females. Histological examinations of the thyroid of the 5.0% group revealed marked hypertrophy and/or hyperplasia of the follicles, some with depletion of colloid and some with rich colloid, and formation of a fibrous capsule. Slight hypertrophy of follicular cells was observed in male rats fed a diet containing 1.25% of P-60 (1.25% group) and female rats fed a diet containing 2.5% of P-60 (2.5% group). Degree and incidence of thyroid lesions were higher in males than in females in the 1.25, 2.5 and 5.0% groups. In the 2-8-week studies, five rats of each sex were given diets containing 0 (control) and 5.0% of P-60. In the 5.0% group, the mean thyroid weight in males significantly increased to 161% of the control as early as 2 weeks and increased to 357% of the control at 8 weeks. Histologically, these goiters were also associated with follicular cell hypertrophy/hyperplasia as in the 13-week study. The degree and incidence of thyroid lesions were higher in males than in females. These results indicate that dietary administration of the green tea extract catechins at high doses induced goiters in rats, and this may be due to antithyroid effects of catechins. In the 13-week study, the no-observed effect level (NOEL) of green tea extract catechins for F344 rats based on histological changes of the thyroid was considered to be 0.625% in males and 1.25% in females in the diet, respectively.

152. Ann N Y Acad Sci. 2001 Apr;928:274-80.

A new function of green tea: prevention of lifestyle-related diseases.

Sueoka N, Suganuma M, Sueoka E, Okabe S, Matsuyama S, Imai K, Nakachi K, Fujiki H.

Saitama Cancer Center Research Institute, Japan.

In the normal human life span, there occur lifestyle-related diseases that may be preventable with nontoxic agents. This paper deals with the preventive activity of green tea in some lifestyle-related diseases. Green tea is one of the most practical cancer preventives, as we have shown in various in vitro and in vivo experiments, along with epidemiological studies. Among various biological effects of green tea, we have focused on its inhibitory effect on TNF-alpha gene expression mediated through inhibition of NF-kappaB and AP-1 activation. Based on our recent results with TNF-alpha-deficient mice, TNF-alpha is an endogenous tumor promoter. TNF-alpha is also known to be a central mediator in chronic inflammatory diseases such as rheumatoid arthritis and multiple sclerosis. We therefore hypothesized that green tea might be a preventive agent for chronic inflammatory diseases. To test this hypothesis, TNF-alpha transgenic mice, which overexpress TNF-alpha only in the lungs, were examined. The TNF-alpha transgenic mouse is an animal model of human idiopathic pulmonary fibrosis which also frequently develops lung cancer. Expressions of TNF-alpha and IL-6 were inhibited in the lungs of these mice after treatment with green tea in drinking water for 4 months. In addition, judging from the results of a prospective cohort study in Saitama Prefecture, Japan, green tea helps to prevent cardiovascular disease. In this study, a decreased relative risk of death from cardiovascular disease was found for people consuming over 10 cups of green tea a day, and green tea also had life-prolonging effects on cumulative survival. These data suggest that green tea has preventive effects on both chronic inflammatory diseases and lifestyle-related diseases (including cardiovascular disease and cancer), resulting in prolongation of life span.

153. Rocz Akad Med Bialymst. 2001;46:240-50.

The influence of green tea on the activity of proteases and their inhibitors in plasma of rats after ethanol treatment.

Skrzydlewska E, Roszkowska A, Makiela M, Skrzydlewski Z.

Department of Analytical Chemistry, Medical Academy of Bialystok, Bialystok, Poland.

Ethanol oxidation in the liver is accompanied by formation of acetaldehyde and free radicals. These compounds can react with biologically active proteins, including proteolytic enzymes and their inhibitors. The aim of this paper was to determine the influence of green tea on the activity of cathepsin G and elastase and their inhibitors such as alpha-1-antitrypsin and alpha-2-macroglobulin, total antioxidant status and lipid peroxidation in plasma of young rats chronically intoxication with ethanol. The activity of cathepsin G and elastase was increased, while the activity of their inhibitors was reduced after ethanol treatment. AT the same time, the total antioxidant status was significantly decreased while lipid peroxidation measured as malondialdehyde and 4-hydroxynonenal was significantly increased. Giving green tea to rats did not change the proteases and their inhibitors activity, but significantly increased total antioxidant status and decreased lipid peroxidation. Drinking green tea with ethanol partially prevents the changes observed after ethanol intoxication.

154. Hong Kong Med J. 2001 Dec;7(4):369-74.

The medicinal action of androgens and green tea epigallocatechin gallate.

Liao S.

Tang Center for Herbal Medicine Research, Ben May Institute for Cancer Research, University of Chicago, Chicago, Illinois, USA.

Unorthodox (non-traditional or alternative) medicinal practices have been expanding very rapidly in western countries. Modern physicians, scientists, and non-traditional medicine practitioners now must join forces to promote evidence-based medicine to benefit patients. Green tea extracts are among the most widely used ancient medicinal agents, while androgens are probably the oldest drugs used in a purified form in traditional Chinese medicine. It is now clear that a specific green tea catechin, (-)epigallocatechin-3-gallate, can modulate the production and biological actions of androgens and other hormones. Modulation of androgenic activity and administration of (-)epigallocatechin-3-gallate may be useful for the treatment of various hormone-related abnormalities, such as benign prostatic hyperplasia, baldness, and acne, as well as androgen-dependent and -independent prostate cancers. (-)Epigallocatechin-3-gallate has also been shown to modulate appetite and control obesity in animals.

155. Nutr Cancer. 2001;39(2):239-43.

Effects of green tea on colonic aberrant crypt foci and proliferative indexes in rats.

Jia X, Han C.

Institute of Nutrition and Food Hygiene, Chinese Academy of Preventive Medicine, Beijing 100050, People's Republic of China.

The present study was designed to investigate the effect of green tea on 1,2-dimethylhydrazine (DMH)-induced aberrant crypt foci (ACF) formation in Wistar rats. Forty-five male weanling Wistar rats were randomly divided into three groups. Rats in Group 1 were injected with DMH (20 mg/kg s.c.) once a week for 10 weeks. Animals in Group 2 received 2% green tea water extract as the sole source of drinking fluid in addition to the same treatment used for Group 1. Group 3 was the negative control group. Animals were killed at the end of Week 16 after the first DMH treatment. ACF were formed in animals in their DMH-treated groups at the end of Week 16. Group 2 had fewer ACF than Group 1. Compared with the positive control group, proliferating cell nuclear antigen labeling index, silver-stained nucleolar organizer regions, and ras-p21 expression were significantly reduced in Group 2. It was concluded that green tea drinking inhibited ACF formation in rats, and such effects may be related to the suppression of cell proliferation in the intestinal crypts.

156. Eur J Pharmacol. 2002 Jan 2;434(1-2):1-7.

Green tea polyphenols inhibit human vascular smooth muscle cell proliferation stimulated by native low-density lipoprotein.

Locher R, Emmanuele L, Suter PM, Vetter W, Barton M.

Department of Internal Medicine, Medical Policlinic and Clinical Atherosclerosis Research Laboratory, University Hospital Zurich, Ramistrasse 100, CH-8091 Zurich, Switzerland.

This study investigated whether human vascular smooth muscle cell proliferation induced by native low-density lipoprotein (LDL) is affected by green tea catechins. Furthermore, the effects of native LDL on extracellular signal-regulated kinase (ERK) 1/2 activity were determined. Cell proliferation stimulated by native LDL was concentration-dependently inhibited by epigallocatechin, epigallocatechin-3-gallate, green tea polyphenon, and the nonspecific antioxidant N-acetylcysteine (P<0.05). Combined treatment of green tea polyphenon and N-acetylcysteine markedly potentiated the effect of each drug on vascular smooth muscle cell proliferation. ERK1/2 activity was only partly inhibited by green tea catechins alone or in combination with N-acetylcysteine (P<0.05). These data suggest that green tea constituents inhibit proliferation of human vascular smooth muscle cells exposed to high levels of native LDL. Green tea constituents and antioxidants may exert vascular protection by inhibiting human vascular smooth muscle cell growth associated with hypercholesterolemia.

157. J Biomed Sci. 1994 Jun;1(3):163-166.

Inhibitory Effects of Polyphenolic Catechins from Chinese Green Tea on HIV Reverse Transcriptase Activity.

Chang CW, Hsu FL, Lin JY.

Institute of Biochemistry, College of Medicine, National Taiwan University, Taipei, Taiwan, ROC.

Three polyphenolic catechins, epigallocatechin (1), epicatechin-3-O-gallate (2) and epigallocatechin-3-O-gallate (3), were isolated from Chinese green tea, Ti-Kaun-Yin (Camellia sinensis) and demonstrated as a new class of human immunodeficiency virus-reverse transcriptase (HIV-RT) inhibitor. The concentrations required for 50% inhibition for the compounds (1), (2) and (3) were 7.80, 0.32 and 0.68 &mgr;M, respectively. The polyphenolic catechins with a galloyl group at the 3 position were potent inhibitors of HIV-RT. Kinetic analysis indicated that the polyphenolic catechins were competitive inhibitors with respect to the template-primer (rA)(n)(dT)(12-18) and noncompetitive inhibitors to dTTP. Copyright 1994 S. Karger AG, Basel

158. J Agric Food Chem. 2001 Nov;49(11):5639-45.

Green tea upregulates the low-density lipoprotein receptor through the sterol-regulated element binding Protein in HepG2 liver cells.

Bursill C, Roach PD, Bottema CD, Pal S.

CSIRO Health Sciences and Nutrition, Adelaide, SA 5000, Australia.

Green tea from Camellia sinensis lowers plasma cholesterol in animal models of hypercholesterolemia. The aim of this study was to determine the effects of green tea on the expression of the hepatic low-density lipoprotein (LDL) receptor, a cell surface protein involved in the control of plasma cholesterol. Incubating human HepG2 liver cells in culture with green tea increased both LDL receptor binding activity and protein. An ethyl acetate extract of green tea, containing 70% (w/w) catechins, also increased the LDL receptor binding activity, protein, and mRNA, indicating that (1) the effect was at the level of gene transcription and that (2) the catechins were the active constituents. The mechanism by which green tea up-regulated the LDL receptor was then investigated. Green tea decreased the cell cholesterol concentration (-30%) and increased the conversion of the sterol-regulated element binding protein (SREBP-1) from the inactive precursor form to the active transcription-factor form. Consistent with this, the mRNA of 3-hydroxy-3-methylglutaryl coenzyme A reductase, the rate-limiting enzyme in cholesterol synthesis, was also increased by green tea. In conclusion, green tea up-regulated the LDL receptor in HepG2 cells. The effect was most likely mediated through SREBP-1 in response to a decrease in the intracellular cholesterol concentration. The LDL receptor may therefore play a role in the hypocholesterolemic effect of green tea in vivo.

159. J Agric Food Chem. 2001 Nov;49(11):5340-7.

Factors affecting the caffeine and polyphenol contents of black and green tea infusions.

Astill C, Birch MR, Dacombe C, Humphrey PG, Martin PT.

Unilever Research Colworth, Colworth House, Sharnbrook, Bedford MK44 1LQ, United Kingdom. conrad.astill@unilever.com

The effects of product and preparation variables on the in-cup chemical composition of tea extracts is of interest because the appearance and taste characteristics and the possible health effects of a tea liquor arise from the chemical components extracted from the leaf during tea preparation. A comprehensive study was therefore undertaken to determine the contributions of product and preparation variables on the total soluble solids, caffeine, and polyphenol contents of tea extracts. The results of this study show that the variety, growing environment, manufacturing conditions, and grade (particle size) of the tea leaves each influence the tea leaf and final infusion compositions. In addition, the composition of the tea infusion was shown to be influenced by whether the tea was contained in a teabag and, if so, the size and material of construction of the bag. Finally, the preparation method, including the amounts of tea and water used, infusion time, and amount of agitation, was shown to be a major determinant of the component concentrations of tea beverages as consumed. An illustration of the variation introduced by these product and preparation factors is provided by comparing solids, caffeine, and polyphenol contents of green and black tea infusions when commercial products are prepared according to the instructions given on their packaging.

160. J Cardiovasc Pharmacol. 2001 Dec;38(6):875-84.

Antiplatelet activity of green tea catechins is mediated by inhibition of cytoplasmic calcium increase.

Kang WS, Chung KH, Chung JH, Lee JY, Park JB, Zhang YH, Yoo HS, Yun YP.

College of Pharmacy, Chungbuk National University, 48 Gaesin-Dong, Heungduk-Gu, Cheongju, 361-763, Korea.

We have previously reported that green tea catechins (GTC) display a potent antithrombotic activity, which might be due to antiplatelet rather than anticoagulation effects. In the current study, we investigated the antiplatelet mechanism of GTC. We tested the effects of GTC on the aggregation of human platelets and on the binding of fluorescein isothiocyanate-conjugated fibrinogen to human platelet glycoprotein (GP) IIb/IIIa. GTC inhibited the collagen-, thrombin-, adenosine diphosphate (ADP)-, and calcium ionophore A23187-induced aggregation of washed human platelets, with 50% inhibitory concentration values of 0.64, 0.52, 0.63, and 0.45 mg/ml, respectively. GTC significantly inhibited fibrinogen binding to human platelet surface GPIIb/IIIa complex but failed to inhibit binding to purified GPIIb/IIIa complex. These results indicate that the antiplatelet activity of GTC may be due to inhibition of an intracellular pathway preceding GPIIb/IIIa complex exposure. We also investigated the effects of GTC on intracellular calcium levels, which are critical in determining the activation status of platelets and on induction of platelet aggregation by thapsigargin, which is a selective inhibitor of the Ca(2+)-ATPase pump. Pretreatment of human platelets with GTC significantly inhibited the rise in intracellular Ca(2+) concentration induced by thrombin treatment, and GTC significantly inhibited the thapsigargin-induced platelet aggregation. We also examined the effect of GTC on the second messenger, inositol 1,4,5-triphosphate (IP(3)). GTC significantly inhibited the phosphoinositide breakdown induced by thrombin. Taken together, these observations suggest that the antiplatelet activity of GTC is be mediated by inhibition of cytoplasmic calcium increase, which leads to the inhibition of fibrinogen-GPIIb/IIIa binding via the activation of Ca(2+)-ATPase and inhibition of IP(3) formation.

161, Biochem Pharmacol. 2001 Nov 1;62(9):1175-83.

Effects of purified green and black tea polyphenols on cyclooxygenase- and lipoxygenase-dependent metabolism of arachidonic acid in human colon mucosa and colon tumor tissues.

Hong J, Smith TJ, Ho CT, August DA, Yang CS.

Laboratory for Cancer Research, College of Pharmacy, Rutgers, The State University of New Jersey, 164 Frelinghuysen Road, Piscataway, NJ 08854-8020, USA.

The effects of green and black tea polyphenols on cyclooxygenase (COX)- and lipoxygenase (LOX)-dependent arachidonic acid metabolism in normal human colon mucosa and colon cancers were investigated. At a concentration of 30 microg/mL, (-)-epigallocatechin-3-gallate (EGCG), (-)-epigallocatechin (EGC), and (-)-epicatechin-3-gallate (ECG) from green tea and theaflavins from black tea inhibited LOX-dependent activity by 30-75%. The formation of 5-, 12-, and 15-LOX metabolites was inhibited to a similar extent. Tea polyphenols also inhibited COX-dependent arachidonic acid metabolism in microsomes from normal colon mucosa, with ECG showing the strongest inhibition. The formation of thromboxane (TBX) and 12-hydroxyheptadecatrienoic acid (HHT) was decreased to a greater extent than other metabolites. The inhibitory effects of tea polyphenols on COX activity, however, were less pronounced in tumor microsomes than in normal colon mucosal microsomes. Theaflavins strongly inhibited the formation of TBX and HHT, but increased the production of prostaglandin E(2) (PGE(2)) in tumor microsomes. The enhancing effect of theaflavins on PGE(2) production was related to the COX-2 level in the microsomes. Although theaflavin inhibited ovine COX-2, its activity in the formation of PGE(2) was stimulated by theaflavin when ovine COX-2 was mixed with microsomes, suggesting that theaflavin affects the interaction of COX-2 with other microsomal factors (e.g. PGE synthase). The present results indicate that tea polyphenols can affect arachidonic acid metabolism in human colon mucosa and colon tumors, and this action may alter the risk for colon cancer in humans.

162. Biochem Biophys Res Commun. 2001 Nov 16;288(5):1200-6.

Green tea epigallocatechin gallate: a natural inhibitor of fatty-acid synthase.

Wang X, Tian W.

Department of Biology, Graduate School of Chinese Academy of Sciences, Beijing 100039, China.

We discover that epigallocatechin gallate (EGCG) from green tea is an inhibitor of fatty-acid synthase (FAS) from chicken liver. Its inhibition of FAS is composed of reversible fast-binding inhibition, through which 52 microM EGCG can inhibit 50% of the activity of FAS, and irreversible slow-binding inactivation following saturation kinetics with the dissociation constant of 0.352 mM and limiting rate constant of 0.0168 min(-1). The marked inhibition of ketoacyl reduction shows that the inhibition is related to beta-ketoacyl reductase of FAS. The observable protection of NADPH and competitive inhibition of NADPH for ketoacyl reduction indicate that EGCG may compete with NADPH for the same binding site. The synthetic inhibitor C75 does not show obvious fast-binding inhibition, but does exhibit irreversible slow-binding biphasic inactivation, which is demonstrated to be a second-order reaction. That the inactivation by C75 is protected by malonyl-CoA indicates C75 is similar to cerulenin in being a covalent inactivator of the beta-ketoacyl synthase. Copyright 2001 Academic Press.

163. J Biol Chem. 2002 Jan 18;277(3):1828-36. Epub 2001 Nov 06.

Green tea polyphenol stimulates a Ras, MEKK1, MEK3, and p38 cascade to increase activator protein 1 factor-dependent involucrin gene expression in normal human keratinocytes.

Balasubramanian S, Efimova T, Eckert RL.

Department of Physiology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106-4970, USA.

(-)-Epigallocatechin-3-gallate (EGCG) is an important bioactive constituent of green tea that efficiently reduces epidermal cancer cell proliferation. This inhibition is associated with a reduction in activator protein 1 (AP1) transcription factor level and activity. However, its effects on AP1 function in normal epidermal cells have not been extensively explored. Our present studies show that EGCG regulates normal keratinocyte function. To understand the mechanism of action, we examined the effects of EGCG on AP1 factor activity, MAPK signal transduction, and expression of the AP1 factor-regulated human involucrin (hINV) gene. EGCG increases hINV promoter activity in a concentration-dependent manner that requires the presence of an intact hINV promoter AP1 factor binding site. This response appears to be physiologic, as endogenous hINV gene expression is also increased. Fra-1, Fra-2, FosB, JunB, JunD, c-Jun, and c-Fos levels are increased by EGCG treatment, as is AP1 factor binding to hINV promoter AP1 site. Gel mobility shift studies show that this complex contains Fra-1 and JunD. Signal transduction analysis indicates that the EGCG response requires Ras, MEKK1, MEK3, and p38 kinases. Kinase assays and inhibitor studies suggest that p38delta is the p38 isoform responsible for the regulation. These changes are also associated with a cessation of cell proliferation and enhanced cornified envelope formation. These studies show that in normal human keratinocytes EGCG markedly increases, via a MAPK signaling mechanism, AP1 factor-associated responses.

164. Epidemiology. 2001 Nov;12(6):695-700.

A population-based case-control study of lung cancer and green tea consumption among women living in Shanghai, China.

Zhong L, Goldberg MS, Gao YT, Hanley JA, Parent ME, Jin F.

Gilead Sciences, Forest City, California, USA.

Epidemiologic evidence regarding the association between the consumption of green tea and lung cancer is limited and inconclusive, although experimental studies have shown consistently that tea preparations and tea polyphenols may inhibit the induction of a variety of cancers, including lung cancer. In this population-based case-control study, we examined the association between past consumption of green tea and the risk of lung cancer. We identified 649 incident cases of primary lung cancer among women diagnosed from February 1992 through January 1994 using the population-based Shanghai Cancer Registry. We randomly selected a control group of 675 women from the Shanghai Residential Registry, frequency-matched to the expected age distribution of the cases. Green tea consumption was ascertained through face-to-face interviews. We estimated adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) using unconditional logistic regression. Among nonsmoking women, consumption of green tea was associated with a reduced risk of lung cancer (OR = 0.65; 95% CI = 0.45-0.93), and the risks decreased with increasing consumption. We found little association, however, among women who smoked (OR = 0.94; 95% CI = 0.40-2.22). The inconsistency in the association between drinking tea and the risk of lung cancer reported in previous studies may in part be due to inadequate control of confounding of active smoking.

165. Mutat Res 2001 Sep 1;480-481:147-51 Protective effect of green tea against benzo[a]pyrene-induced mutations in the liver of Big Blue transgenic mice. Jiang T, Glickman BW, de Boer JG. Laboratory of Industrial Hygiene, Ministry of Health, Beijing, PR China.

We assessed the ability of green tea to protect against benzo[a]pyrene (B[a]P)-induced mutations in the liver of lacI transgenic male C57BL/6 Big Blue mice. The mice were given a 2% Japanese green tea hot water extract as their sole source of drinking water for 10 weeks. After 7 weeks, they received a total dose of 150 mg/kg B[a]P. Treatment with B[a]P resulted in a two-fold higher lacI mutant frequency than the untreated controls (8.6+/-0.8 x 10(-5) versus 4.0+/-0.7 x 10(-5), P=0.01). B[a]P increased the frequency of its characteristic mutation (GC-->TA transversions) nearly five-fold, from 0.75 x 10(-5) to 3.7 x 10(-5). In mice treated with green tea, the induced B[a]P mutant frequency decreased by 63%, while GC-->TA transversions were reduced by 54%. Thus, we report evidence that green tea extract significantly suppressed B[a]P-induced mutation by lowering its specific transversion mutation in the lacI transgene in vivo. Further studies will address the correlation between the modulation of metabolic enzymes and the protection against induced mutation by green tea.

166. J Nutr 2001 May;131(5):1560-7 Green tea suppresses lipopolysaccharide-induced liver injury in d-galactosamine-sensitized rats. He P, Noda Y, Sugiyama K. Department of Applied Biological Chemistry, Faculty of Agriculture, Shizuoka University, Shizuoka 422-8529, Japan.

We conducted a series of in vivo experiments to clarify the hepatoprotective activity of green tea against lipopolysaccharide (LPS) + D-galactosamine (GalN)-induced liver injury and to elucidate the mechanism by which green tea exerts its effect in 7-wk-old male Wistar rats. Liver injury was assessed by plasma alanine aminotransferase and aspartate aminotransferase activities. Green tea extract significantly suppressed LPS + GalN-induced liver injury when added to the diet (30 or 35 g/kg) and fed to rats for 14 d or when force-fed alone (0.4-1.2 g/kg body) 1.5 h before the injection of drugs. Although all five of the fractions extracted from green tea extract with different organic solvents had significant suppressive effects, the caffeine-containing fraction exhibited the strongest effect, suggesting that the protective effect of green tea against LPS + GalN-induced liver injury is attributable mainly to caffeine. Authentic caffeine also significantly suppressed LPS + GalN-induced liver injury when added to the diet (2 g/kg) and fed to rats for 14 d. Dietary green tea suppressed LPS + GalN-induced apoptosis of liver cells, as assessed by DNA fragmentation. However, dietary green tea did not suppress LPS-induced enhancement of plasma concentration of tumor necrosis factor (TNF)-alpha, the cytokine that is thought to play a pivotal role in the pathogenesis of LPS-induced liver injury, although it significantly suppressed plasma concentrations of interleukin (IL)-1beta, IL-2, IL-4, IL-6, IL-10 and interferon (IFN)-gamma. TNF-alpha + GalN-induced liver injury and apoptosis were also suppressed by dietary green tea. In contrast, dietary caffeine significantly suppressed LPS-induced enhancement not only of plasma IL-1beta, IL-6, IL-10 and IFN-gamma concentrations, but also of TNF-alpha concentration. The results suggest that green tea might suppress LPS + GalN-induced liver injury mainly through the inhibition of TNF-alpha-induced apoptosis of hepatocytes, rather than through the suppression of TNF-alpha production, although the suppressed production of TNF-alpha may be associated with the hepatoprotective effect of caffeine.

167. Chem Biol Interact 2001 Mar 14;134(1):41-54 Stereospecificity in membrane effects of catechins. Tsuchiya H Department of Dental Pharmacology, Asahi University School of Dentistry, 1851 Hozumi, Hozumi-cho, Motosu-gun, 501-0296, Gifu, Japan

Green tea catechins consisting of catechin stereoisomers and their derivatives have been suggested to show biological activities through the interactions with cellular membranes. Their effects on membrane fluidity were comparatively studied by measuring fluorescence polarization of liposomal membranes prepared with phospholipids and cholesterol. All catechin stereoisomers reduced membrane fluidity by acting on the hydrophilic and hydrophobic regions of membrane bilayers at 20-500 ?M. Both epicatechins in a cis form were more effective for reducing membrane fluidity than both catechins in a trans form. (-)-Epicatechin, (+)-epicatechin, (-)-catechin and (+)-catechin reduced membrane fluidity in increasing order of intensity. Such difference between optical isomers was increased by chiral cholesterol added to membrane lipids. In reversed-phase chromatographic evaluation, (-)-epicatechin and (+)-epicatechin were more hydrophobic than (-)-catechin and (+)-catechin, although hydrophobicity was not distinguishable between optical isomers. Stereospecificity in the membrane effects of catechin stereoisomers may be induced by the different hydrophobicity of geometrical isomers and the chirality of membrane lipid components. At lower concentrations (5-100 ?M), (-)-epigallocatechin gallate and (-)-epicatechin gallate reduced membrane fluidity more significantly than (-)-epicatechin, suggesting that the intensive membrane effect contributes to the potent medicinal utility of (-)-epigallocatechin gallate.

168. Mutat Res 2001 Mar 1;474(1-2):71-85

Antimutagenic activity of green tea and black tea extracts studied in a dynamic in vitro gastrointestinal model.

Krul C, Luiten-Schuite A, Tenfelde A, van Ommen B, Verhagen H, Havenaar R

TNO Nutrition and Food Research, P.O. Box 360, 3700, AJ Zeist, The Netherlands

[Medline record in process]

An in vitro gastrointestinal model, which simulates the conditions in the human digestive tract, was used to determine potential antimutagenic activity of extracts of black tea and green tea. In this paper, results are presented on the availability for absorption of potential antimutagenic compounds present in tea and on the influence of the food matrix on this activity. Between 60 and 180min after the tea was introduced into the model, antimutagenic activity was recovered from the jejunal compartment by means of dialysis: the dialysate appeared to inhibit the mutagenicity of the food mutagen MeIQx in the direct plate assay with Salmonella typhimurium (Ames test). The maximum inhibition was measured at 2h after the start of the experiment and was comparable for black tea and green tea extract. To determine the influence of food matrices on the antimutagenic activity of tea, the model was loaded with black tea together with milk or a homogenized standard breakfast. The maximum inhibition observed with black tea was reduced by 22, 42 and 78% in the presence of whole milk, semi-skimmed milk, and skimmed milk, respectively. Whole milk and skimmed milk abolished the antimutagenic activity of green tea by more than 90%; for semi-skimmed milk the inhibition was more than 60%. When a homogenized breakfast was added into the model together with the black tea extract, the antimutagenic activity was completely eliminated. When tea and MeIQx were added together into the digestion model, MeIQx mutagenicity was efficiently inhibited, with green tea showing a slightly stronger antimutagenic activity than black tea. In this case, the addition of milk had only a small inhibiting effect on the antimutagenicity.Antioxidant capacity and the concentration of catechins were also measured in the jejunal dialysates. The reduction in antimutagenic activity corresponded with reduction in antioxidant capacity and with a decrease of concentration of three catechins, viz. catechin, epigallocatechin gallate and epigallocatechin. The in vitro gastrointestinal model appears to be a useful tool to study the antimutagenicity of food components.

169. Comp Biochem Physiol C Toxicol Pharmacol 2001 Feb;128(2):153-64

Tea catechins inhibit cholesterol oxidation accompanying oxidation of low density lipoprotein in vitro.

Osada K, Takahashi M, Hoshina S, Nakamura M, Nakamura S, Sugano M

Department of Applied Life Science, Faculty of Agriculture and Life Science, Hirosaki University, 3 Bunkyo-cho, Hirosaki, 036-8561, Aomori, Japan

[Medline record in process]

Endogenous oxidized cholesterols are potent atherogenic agents. Therefore, the antioxidative effects of green tea catechins (GTC) against cholesterol oxidation were examined in an in vitro lipoprotein oxidation system. The antioxidative potency of GTC against copper catalyzed LDL oxidation was in the decreasing order (-)-epigalocatechin gallate (EGCG)=(-)-epicatechin gallate (ECG)>(-)-epicatechin (EC)=(+)-catechin (C)>(-)-epigallocatechin (EGC). Reflecting these activities, both EGCG (74%) and ECG (70%) inhibited the formation of oxidized cholesterol, as well as the decrease of linoleic and arachidonic acids, in copper catalyzed LDL oxidation. The formation of oxidized cholesterol in 2,2'-azobis(2-amidinopropane) hydrochloride (AAPH)-mediated oxidation of rat plasma was also inhibited when the rats were given diets containing 0.5% ECG or EGCG. In addition, EGCG and ECG highly inhibited oxygen consumption and formation of conjugated dienes in AAPH-mediated linoleic acid peroxidative reaction. These two species of catechin also markedly lowered the generation of hydroxyl radical and superoxide anion. Thus, GTC, especially ECG and EGCG, seem to inhibit cholesterol oxidation in LDL by combination of interference with PUFA oxidation, the reduction and scavenging of copper ion, hydroxyl radical generated from peroxidation of PUFA and superoxide anion.

170. Life Sci 2001 Jan 26;68(10):1207-14

Induction of apoptosis by green tea catechins in human prostate cancer DU145 cells.

Chung LY, Cheung TC, Kong SK, Fung KP, Choy YM, Chan ZY, Kwok TT

Department of Biochemistry, The Chinese University of Hong Kong, Shatin.

Green tea catechins (GTCs) including (-)-epigallocatechin-3-gallate (EGCG), (-)-epigallocatechin (EGC), (-)-epicatechin-3-gallate (ECG) and (-)-epicatechin (EC) were shown to suppress cell growth and induce apoptosis in various cell systems in addition to their chemo-preventive effect. In this study, except EC which was inactive, green tea extract (TE) and other 3 GTCs were found to suppress the growth and induce apoptosis in human prostate cancer DU145 cells largely through an increase in reactive oxygen species formation and mitochondrial depolarization. The conclusion was supported by the fact that the profiles for different GTCs in growth suppression, apoptosis induction, ROS formation and mitochondrial depolarization are in a similar order, i.e. ECG > EGCG > EGC > EC. Although the molecular mechanisms are still not clear, apoptosis induced by GTCs is not related to the members of BCL-2 family as EGCG did not alter the expression of BCL-2, BCL-X(L) and BAD in DU145 cells.

171. J Nutr 2001 Jan;131(1):27-32

Tea catechins Prevent the Development of Atherosclerosis in Apoprotein E-Deficient Mice.

Miura Y, Chiba T, Tomita I, Koizumi H, Miura S, Umegaki K, Hara Y, Ikeda M, (daggerdagger) 2;

School of Pharmaceutical Sciences, University of Shizuoka, 52-1, Yada, Shizuoka, 422-8526, Japan. Shizuoka Sangyo University, 4-1-1, Surugadai, Fujieda, Shizuoka, 426-8668, Japan. Central Pharmaceutical Research Institute, Japan Tobacco Incorporated 23, Nukogi, Hatano, Kanagawa, 257-0024, Japan. National Institute of Nutrition and Health, 1-23-1, Toyama, Shinjuku-ku, Tokyo, Japan. Food Research Laboratories, Mitsui Nohrin Company Limited, 223-1, Miyahara, Fujieda, 426-0133, Japan. University of Shizuoka, Graduate School of Health Sciences, 52-1, Yada, Shizuoka, 422 8526, Japan.

[Record supplied by publisher]

Green tea contains various antioxidative flavan-3ols (tea catechins), such as (-)-epigallocatechin gallate (EGCg, the major catechin), which exert potent inhibitory effects on LDL oxidation in vitro and ex vivo in humans. In this study, the antiatherogenic effects of tea catechins were examined in atherosclerosis-susceptible C57BL/6J, apoprotein (apo)E-deficient mice. Male apoE-deficient mice (10 wk old) were fed an atherogenic diet for 14 wk; during that time, one group (tea) was supplied drinking water supplemented with green tea extract (0.8 g/L), and another group (control) was offered the vehicle only. The tea extract consisted of the following (g/100 g): EGCg, 58.4; (-)-epigallocatechin (EGC), 11.7; (-)-epicatechin (EC), 6.6; (-)-gallocatechingallate (GCg), 1.6; (-)-epicatechin gallate (ECg), 0.5; and caffeine, 0.4. The estimated actual intake of tea catechin was 1.7 mg/(d. mouse). Tea ingestion did not influence plasma cholesterol or triglyceride concentrations. Plasma lipid peroxides were reduced in the tea group at wk 8, suggesting that the in vivo oxidative state is improved by tea ingestion. Atheromatous areas in the aorta from the arch to the femoral bifurcation and aortic weights were both significantly attenuated by 23% in the tea group compared with the control group. Aortic cholesterol and triglyceride contents were 27 and 50% lower, respectively, in the tea group than in the control group. These results suggest that chronic ingestion of tea extract prevents the development of atherosclerosis without changing the plasma lipid level in apoE-deficient mice, probably through the potent antioxidative activity of the tea.

172. Cancer Epidemiol Biomarkers Prev 2001 Jan;10(1):53-8

Phase I pharmacokinetic study of tea polyphenols following single-dose administration of epigallocatechin gallate and polyphenon E.

Chow HH, Cai Y, Alberts DS, Hakim I, Dorr R, Shahi F, Crowell JA, Yang CS, Hara Y

Arizona Cancer Center, The University of Arizona, Tucson 85724, USA. schow@azcc.arizona.edu

[Medline record in process]

Green tea has been shown to exhibit cancer-preventive activities in preclinical studies. Its principal active components include epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin (EC), and epicatechin gallate, of which EGCG is the most abundant and possesses the most potent antioxidative activity. We performed a Phase I pharmacokinetic study to determine the systemic availability of green tea catechins after single oral dose administration of EGCG and Polyphenon E (decaffeinated green tea catechin mixture). Twenty healthy subjects (five subjects/dose level) were randomly assigned to one of the dose levels (200, 400, 600, and 800 mg based on EGCG content). All subjects were randomly crossed-over to receive the two catechin formulations at the same dose level. Blood and urine samples were collected for up to 24 h after oral administration of the study medication. Tea catechin concentrations in plasma and urine samples were determined using high-performance liquid chromatography with the coulometric electrode array detection system. After EGCG versus Polyphenon E administration, the mean area under the plasma concentration-time curves (AUC) of unchanged EGCG were 22.5 versus 21.9, 35.4 versus 52.2, 101.9 versus 79.7, and 167.1 versus 161.4 min x microg/ml at the 200-, 400-, 600-, and 800-mg dose levels, respectively. EGC and EC were not detected in plasma after EGCG administration and were present at low/undetectable levels after Polyphenon E administration. High concentrations of EGC and EC glucuronide/sulfate conjugates were found in plasma and urine samples after Polyphenon E administration. There were no significant differences in the pharmacokinetic characteristics of EGCG between the two study medications. The AUC and maximum plasma concentration (Cmax) of EGCG after the 800-mg dose of EGCG were found to be significantly higher than those after the 200- and 400-mg dose. The AUC and Cmax of EGCG after the 800-mg dose of Polyphenon E were significantly higher than those after the three lower doses. We conclude that the two catechin formulations resulted in similar plasma EGCG levels. EGC and EC were present in the body after the Polyphenon E administration; however, they were present predominantly in conjugated forms. The systemic availability of EGCG increased at higher doses, possibly due to saturable presystemic elimination of orally administered green tea polyphenols.

173. Arch Pharm Res 2000 Dec;23(6):605-12

Activation of antioxidant-response element (ARE), mitogen-activated protein kinases (MAPKs) and caspases by major green tea polyphenol components during cell survival and death.

Chen C, Yu R, Owuor ED, Kong AN

Department of Pharmaceutics and Pharmacodynamics, College of Pharmacy, University of Illinois at Chicago, IL 60607-7173, USA.

[Medline record in process]

Green tea polyphenols (GTP) have been demonstrated to suppress tumorigenesis in several chemical-induced animal carcinogenesis models, and predicted as promising chemopreventive agents in human. Recent studies of GTP extracts showed the involvement of mitogen-activated protein kinases (MAPKs) in the regulation of Phase II enzymes gene expression and induction of apoptosis. In the current work we compared the biological actions of five green tea catechins: (1) induction of ARE reporter gene, (2) activation of MAP kinases, (3) cytotoxicity in human hepatoma HepG2-C8 cells, and (4) caspase activation in human cervical squamous carcinoma HeLa cells. For the induction of phase II gene assay, (-)-epigallocatechin-3-gallate (EGCG) and (-)-epicatechin-3-gallate (ECG) potently induced antioxidant response element (ARE)-mediated luciferase activity, with induction observed at 25 microM with EGCG. The induction of ARE reporter gene appears to be structurally related to the 3-gallate group. Comparing the activation of MAPK by the five polyphenols, only EGCG showed potent activation of all three MAPKs (ERK, JNK and p38) in a dose- and time-dependent manner, whereas EGC activated ERK and p38. In the concentration range of 25 microM to 1 mM, EGCG and ECG strongly suppressed HepG2-ARE-C8 cell-growth. To elucidate the mechanisms of green tea polyphenol-induced apoptosis, we measured the activation of an important cell death protein, caspase-3 induced by EGCG, and found that caspase-3 was activated in a dose- and time-dependent manner. Interestingly, the activation of caspase-3 was a relatively late event (peaked at 16 h), whereas activation of MAPKs was much earlier (peaked at 2 h). It is possible, that at low concentrations of EGCG, activation of MAPK leads to ARE-mediated gene expression including phase II detoxifying enzymes. Whereas at higher concentrations of EGCG, sustained activation of MAPKs such as JNK leads to apoptosis. These mechanisms are currently under investigation in our laboratory. As the most abundant catechin in GTP extract, we found that EGCG potently induced ARE-mediated gene expression, activated MAP kinase pathway, stimulated caspase-3 activity, and induced apoptosis. These mechanisms together with others, may contribute to the overall chemopreventive function of EGCG itself as well as the GTP

174. Planta Med 2000 Dec;66(8):762-4

Protective effects of green tea catechins against asbestos-induced cell injury.

Kostyuk VA, Potapovich AI, Vladykovskaya EN, Hiramatsu M

[Medline record in process]

Green tea extract was found to provide a strong protective effect against asbestos-induced injury of peritoneal macrophages and red blood cells in vitro. The main polyphenolic constituents of green tea extract, (-)-epicatechin gallate (ECG) and (-)-epigallocatechin gallate (EGCG), were also efficient in preventing injury of cells following exposure to asbestos fibers. The protective efficacies of EGCG and ECG expressed as IC50 values were, respectively, 10 microM and 12 microM if peritoneal macrophages were injured by chrysotile and 4 microM and 5 microM in the case of crocidolite-induced cell injury. Antiradical and chelating properties of ECG and EGCG were evaluated and it was concluded that the protective effect of catechins against asbestos-induced injury may be related to both scavenger properties towards to superoxide anion and the ability to chelate iron ions.

175. J Agric Food Chem 2000 Nov;48(11):5768-72

Protection against nitric oxide toxicity by tea.

Paquay JB, Haenen GR, Stender G, Wiseman SA, Tijburg LB, Bast A

Department of Pharmacology and Toxicology, Faculty of Medicine, University of Maastricht, P.O. Box 616, 6200 MD Maastricht, The Netherlands.

It is found that green tea and black tea are able to protect against nitric oxide (NO(*)) toxicity in several ways. Both green tea and black tea scavenge NO(*) and peroxynitrite, inhibit the excessive production of NO(*) by the inducible form of nitric oxide synthase (iNOS), and suppress the LPS-mediated induction of iNOS. The NO(*) scavenging activity of tea was less than that of red wine. The high activity found in the polyphenol fraction of black tea (BTP) could not be explained by the mixed theaflavin fraction (MTF) or catechins [epicatechin, epigallocatechin, epicatechin gallate, epigallocatechin gallate (EGCG)], which were tested separately. Synergistic effects between the compounds, or the presence of a potent, unidentified NO(*) scavenger, may explain the high activity of BTP. The peroxynitrite scavenging of tea was comparable to that of red wine. The main activity was found in the polyphenol fraction. MTF and the catechins were found to be potent peroxynitrite scavengers. Tea and tea components were effective inhibitors of iNOS. Of the tea components tested, only MTF had an activity higher than that of the tea powders. The polyphenol fractions of tea were much more active than the tea powders in suppressing the induction of iNOS. On the basis of its abundance and activity, EGCG was the most active inhibitor. The protective effect of tea on NO(*) toxicity is discussed in relation to the beneficial effect of flavonoid intake on the occurrence of cardiovascular heart disease.

176. Eur J Med Res 2000 Nov 30;5(11):463-7

The effect of sugar-free green tea chew candies on the degree of inflammation of the gingiva.

Krahwinkel T, Willershausen B

Policlinic for Restorative Dentistry, Johannes Gutenberg-University Mainz, Augustusplatz 2, D-55131 Mainz, Germany. krahwink@mail.uni-mainz.de

The components of green tea extracts such as catechins and polyphenols gain increasing significance in tumor research and immunology. - The clinical double blind study presented here was aimed at the investigation on how green tea catechins and polyphenols in the form of green tea dragees may influence the inflammatory behaviour of the gingiva. A total of 47 test persons with a mean age of 25.76 years (23 males, 24 females) were randomly divided into two groups: one group (n = 22: 11 males, 11 females) received chew candies containing green tea extracts, the other group (n = 25: 12 males, 13 females) received placebos with the same flavour but without active substances. At the beginning of the four week investigation period, a professional dental cleaning was carried out on all test persons. Then the persons were instructed to do their usual dental cleaning and chew eight candies distributed over the day. The API (approximal plaque index) and the SBI (sulcus bleeding index) were determined after seven days (API-1, SBI-1) and after another 21 days (API-2, SBI-2). Within the verum group, a mean value of 33.2% +/- 18.3% was determined for API-1, and 29.6% +/- 17.5% for API-2. The mean SBI-1 was 5.9% +/- 7.6%, and 3.6% +/- 5.8% for SBI-2. The clinical data within the placebo group were different: The plaque index values changed from API-1 30.3% +/- 16.3% after one week to API-2 31.8% +/- 17.2% after another three weeks. The values for the inflammatory degree of the gingiva had also changed to the negative: from SBI-1 3.4% +/- 4.1% after seven days to SBI-2 4.7% +/- 6.4% after another 21 days. Whereas in the verum group a distinct improvement in both API and SBI values could be stated, slight worsening of the values were determined for the placebo group. The results indicate that the oral application of green tea catechins and polyphenols might have a positive influence on the inflammatory reaction of periodontal structures.

177. J Nutr Biochem 2000 Nov;11(11-12):536-542

Chemical composition and antioxidant activity of Strobilanthes crispus leaf extract.

Ismail M, Manickam E, Danial AM, Rahmat A, Yahaya A

Department of Nutrition & Health Science, Faculty of Medicine & Health Sciences, University Putra Malaysia, Serdang, Selangor, Malaysia

[Record supplied by publisher]

This study investigated the components present in and the total antioxidant activity of leaves of Strobilanthes crispus (L.) Bremek or Saricocalyx crispus (L.) Bremek (Acanthacea). Proximate analyses and total antioxidant activity using ferric thiocyanate and thiobarbituric acid methods were employed. Minerals content was determined using the atomic absorption spectrophotometer, whereas the water-soluble vitamins were determined by means of the UV-VIS spectrophotometer (vitamin C) and fluorimeter (vitamins B(1) and B(2)). Catechin, tannin, caffeine, and alkaloid contents were also studied. All data were compared to the previously reported results of Yerbamate, green tea, black tea, and Indian tea. The dried leaves contained a high amount of total ash (21.6%) as a result of a high amount of minerals including potassium (51%), calcium (24%), sodium (13%), iron (1%), and phosphorus (1%). High content of water-soluble vitamins (C, B(1), and B(2)) contributed to the high antioxidant activity of the leaves. The leaves also contained a moderate amount of other proximate composition as well as other compounds such as catechins, alkaloids, caffeine, and tannin, contributing further to the total antioxidant activity. Catechins of Strobilanthes crispus leaves showed highest antioxidant activity when compared to Yerbamate and vitamin E. Consumption of the leafy extract daily (5 g/day) as an herbal tea could contribute to the additional nutrients and antioxidants needed in the body to enhance the defense system, especially toward the incidence of degenerative diseases.

178. Chem Biol Interact 2000 Nov 1;128(3):211-29

Comparative studies on the effects of green tea extracts and individual tea catechins on human CYP1A gene expression.

Williams SN, Shih H, Guenette DK, Brackney W, Denison MS, Pickwell GV, Quattrochi LC

Section of Medical Toxicology, Department of Medicine, University of Colorado Health Sciences Center, B146, 4200 East 9th Avenue, 80262, Denver, CO, USA.

Green tea possesses significant anticancer activity in numerous experimental animal models, including demonstrated protection against aryl hydrocarbon induced cancers. The aryl hydrocarbon receptor (AhR) mediates the transcriptional activation of CYP1A1 and CYP1A2. In the present study, we investigated the effects of commercially available green tea extracts (GTEs) and individual tea catechins on the function of the AhR and on CYP1A gene expression in human hepatoma HepG2 cells and primary cultures of human hepatocytes. GTEs inhibited the transcription of a human CYP1A1 promoter-driven reporter gene induced by the AhR ligand 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD) in a concentration-dependent manner and inhibited the induced accumulation of both CYP1A1 and CYP1A2 mRNAs. GTEs blocked TCDD-induced binding of the AhR to DNA in HepG2 cells and in vitro in isolated hepatic cytosol. To determine if the observed effects were due to a single green tea component, we examined the four major catechins present in GTEs. Only (-)-epigallocatechin gallate (EGCG), the most abundant catechin in green tea, was able to inhibit TCDD-induced binding of the AhR to DNA and subsequent CYP1A transcription, however EGCG alone was less effective than GTEs. We next examined GTEs and catechins for AhR agonist activity. GTEs caused a concentration-dependent increase in CYP1A1-promoter driven reporter gene activity and caused accumulation of CYP1A1 mRNA and protein, but we found that individual catechins were unable to induce the expression of CYP1A1. Our results demonstrate that GTEs as a whole exert mixed agonist/antagonist activity on the AhR, while EGCG functions as a strict AhR antagonist. Therefore, modulation of human CYP1A expression by green tea extracts can not be attributed to the action of a single tea catechin, but rather is due to the effects of a complex mixture. These findings may be useful in future studies concerning green tea as a cancer preventive agent.

179. Carcinogenesis 2000 Sep;21(9):1671-6 Prevention of the down-regulation of gap junctional intercellular communication by green tea in the liver of mice fed pentachlorophenol. Sai K, Kanno J, Hasegawa R, Trosko JE, Inoue T. Division of Cellular and Molecular Toxicology and Division of Risk Assessment, National Institute of Health Sciences, 1-18-1 Kamiyohga, Setagayaku, Tokyo 158-8501, Japan.

Much evidence has been documented supporting the hypothesis that the down-regulation of gap junctional intercellular communication (GJIC) is a cellular event underlying the tumor promotion process and that treatment to prevent the down-regulation or to up-regulate GJIC is important in preventing tumor promotion. We explored the potential preventive effects of green tea against the promoting action of pentachlorophenol (PCP) in mouse hepatocarcinogenesis, examining whether drinking green tea prevents the down-regulation of GJIC inhibition in the liver caused by tumorigenic doses of PCP. We used a modified in vivo GJIC assay, the incision loading/dye transfer method. Male B6C3F1 mice were given a green tea infusion for 1 week and then PCP was fed at a dose of 300 or 600 p.p.m. in the diet for the following 2 weeks, along with green tea treatment. A dose-related inhibition of GJIC in the hepatocytes was evident in the mice treated with PCP alone that was associated with a reduction in connexin32 (Cx32) plaques in the plasma membrane and an increase in the cell proliferation index. Drinking green tea significantly protected mice against GJIC inhibition, the reduction in Cx32 and the elevation of the labeling index. These findings suggest that green tea might act as an anti-promoter against PCP-induced mouse hepatocarcinogenesis via its ability to prevent down-regulation of GJIC.

180. Chem Res Toxicol 2000 Sep;13(9):801-10

Antioxidant chemistry of green tea catechins. New oxidation products of (-)-epigallocatechin gallate and (-)-epigallocatechin from their reactions with peroxyl radicals.

Valcic S, Burr JA, Timmermann BN, Liebler DC

Department of Pharmacology and Toxicology, College of Pharmacy, The University of Arizona, Tucson, Arizona 85721, USA.

The green tea catechins (-)-epigallocatechin gallate (EGCG) and (-)-epigallocatechin (EGC) react with peroxyl radicals generated by thermolysis of the azo initiator 2,2'-azobis(2, 4-dimethylvaleronitrile) (AMVN) to produce several oxidation products. Structure elucidation of these products can provide insights into specific mechanisms of antioxidant reactions. We isolated and identified a previously unreported reaction product of EGCG and three reaction products of EGC. In the EGCG product, the B-ring was transformed into a ring-opened unsaturated dicarboxylic acid moiety. The EGC products include a seven-membered B-ring anhydride and a symmetrical EGC dimer, both analogues of previously described EGCG oxidation products. The third EGC product was an unsymmetrical dimer. In all identified products, changes occurred solely in the B-ring of EGCG or EGC. This confirmed our previous observation that the principal site of antioxidant reactions in EGCG and EGC is the trihydroxyphenyl B-ring, regardless of the presence of a 3-galloyl moiety. A stoichiometric factor n of 4.16 +/- 0.51 was measured for EGCG, whereas factors of 2.20 +/- 0.26 was found for EGC and 2.33 +/- 0.18 measured for methyl gallate. These values represent the net peroxyl radical trapping per catechin molecule by several competing reactions. EGCG and EGC oxidation involves addition of oxygen, which is not derived from water, but most likely from atmospheric oxygen via peroxyl radicals. Characteristic oxidation products may be useful markers for antioxidant actions in living systems.

181. Expert Opin Investig Drugs 2000 Sep;9(9):2103-19

The therapeutic potential of flavonoids.

Wang HK

University of North Carolina at Chapel Hill, Room 323, Beard Hill, Chapel Hill, NC 27599-7360, USA. hwang@email.unc.edu

Four most widely investigated flavonoids, flavopiridol, catechins, genistein and quercetin are reviewed in this article. Flavopiridol is a novel semisynthetic flavone analogue of rohitukine, a leading anticancer compound from an Indian tree. Flavopiridol inhibits most cyclin-dependent kinases and displays unique anticancer properties. It is the first cyclin-dependent kinase inhibitor to be tested in Phase II clinical trials. catechin and its gallate are major ingredients in green tea and their anti-oxidant and cancer preventive effects have been widely investigated. A Phase I study of green tea extract GTE-TP91 has been conducted in adult patients with solid tumours. Similarly, genistein is a major ingredient in soybean and has been shown to prevent cancer and have antitumour, anti-oxidant and anti-inflammatory effects. Two antibody-genistein conjugates, B43-genistein and EGF-genistein, are currently in clinical development for the treatment of acute lymphoblastic leukaemia and breast cancer, respectively. Finally, most recent updates of quercetin are briefly described.

182.J Toxicol Sci 2000 Aug;25(3):199-204

Protective effects of (-)-epigallocatechin gallate and (+)-catechin on paraquat-induced genotoxicity in cultured cells.

Tanaka R

Akita Keijo Junior College, Japan.

The protective effects of green tea polyphenols on paraquat-induced genotoxicity in cultured cells were studied. (-)-Epigallocatechin gallate (EGCG), the major constituent of green tea, and (+)-catechin (CT), a minor constituent, equivalently decreased the frequencies of sister-chromatid exchanges (SCE) induced by paraquat (PQ), which is a generator of reactive oxygen species. These polyphenols were effective at concentrations of 1.0 microM and above. A reduction of the effect on the cell cycle rate caused by PQ was found when EGCG and CT were added at concentrations of more than 10.0 microM. These concentrations of EGCG and CT alone had no effect on cell cycle rate, which is used as index of cell proliferation. Decreases in the cell cycle rate were found at 200 microM EGCG and CT in the 24 hr exposure period. The equivalent effectiveness of EGCG and CT suggested the possibility of other mechanisms, apart from acting as reactive oxygen species scavengers, because it has been reported that EGCG is the most potent scavenger among tea catechins. From the present study, it was suggested that green tea and foods containing these polyphenols may be beneficial to human health by protecting against reactive oxygen species-induced genotoxicity.

183. Altern Med Rev 2000 Aug;5(4):372-5

Green tea.

Tea is one of the most widely consumed beverages in the world today, second only to water, and its medicinal properties have been widely explored. The tea plant, Camellia sinensis, is a member of the Theaceae family, and black, oolong, and green tea are produced from its leaves. It is an evergreen shrub or tree and can grow to heights of 30 feet, but is usually pruned to 2-5 feet for cultivation. The leaves are dark green, alternate and oval, with serrated edges, and the blossoms are white, fragrant, and appear in clusters or singly. Unlike black and oolong tea, green tea production does not involve oxidation of young tea leaves. Green tea is produced from steaming fresh leaves at high temperatures, thereby inactivating the oxidizing enzymes and leaving the polyphenol content intact. The polyphenols found in tea are more commonly known as flavonols or catechins and comprise 30-40 percent of the extractable solids of dried green tea leaves. The main catechins in green tea are epicatechin, epicatechin-3-gallate, epigallocatechin, and epigallocatechin-3-gallate (EGCG), with the latter being the highest in concentration. green tea polyphenols have demonstrated significant antioxidant, anticarcinogenic, anti-inflammatory, thermogenic, probiotic, and antimicrobial properties in numerous human, animal, and in vitro studies.

184. J Agric Food Chem 2000 Aug;48(8):3072-6

Oxidative stability of conjugated linoleic acid isomers.

Yang L, Leung LK, Huang Y, Chen ZY

Department of Chemistry, Henan Normal University, Xinxiang, Henan, The Chinese University of Hong Kong, Shatin, New Territories.

Conjugated linoleic acids (CLAs) have been shown to be a strong anticarcinogen in a number of animal models. Our previous study demonstrated that CLA as a whole was extremely unstable in air. The present study was undertaken further to examine the oxidative stability of individual CLA isomers using the combination of gas-liquid chromatography (GLC) and silver ion high-performance liquid chromatography (Ag-HPLC). It was found that CLA as a whole oxidized rapidly and more than 80% was degraded within 110 h in air at 50 degrees C. Four c,c-CLA isomers were most unstable followed by four c,t-CLA isomers. In contrast, four t,t-CLA isomers were relatively stable under the same experimental conditions. Both the oxygen consumption and the GLC analysis revealed that 200 ppm jasmine green tea catechins (GTCs) exhibited protection to CLA and were even stronger than 200 ppm butylated hydroxytoluene (BHT) when added to either CLA or canola oil containing 10% CLA. The present study emphasized that oxidative unstability of CLA should not be overlooked although CLA has many biological effects.

185. Biol Pharm Bull 2000 Jun;23(6):695-9

Inhibitory effects of green tea and grape juice on the phenol sulfotransferase activity of mouse intestines and human colon carcinoma cell line, Caco-2.

Tamura H, Matsui M

Kyoritsu College of Pharmacy, Tokyo, Japan. tamura-hr@kyoritsu-ph.ac.jp

Tea and fruit juices are beverages consumed daily all over the world. The present study reports the inhibitory effects of these beverages on the activity of mammalian intestinal phenol sulfotransferases (P-STs). green tea strongly inhibited the E. coli-expressed mouse intestinal P-ST activity in vitro. (-)-Epigallocatechin gallate (EGCG) was found to be the most potent inhibitor among the catechins tested (IC50=0.93 microM). (-)EGCG also inhibited the P-ST activity of the human colon carcinoma cell line, Caco-2. Kinetic analysis showed that the inhibition was competitive. Among fruit juices examined (apple, grape, grapefruit and orange), grape juice exhibited the most potent inhibitory action on the P-ST activity of mouse intestines and human colon carcinoma cells. The inhibitory activity of grape juice was located mainly in the skin and seeds. Flavonols, such as quercetin and kaempferol, inhibited the P-ST activity at low concentrations. These observations suggest the possible inhibition of P-ST activity in human intestines by green tea or grape juice.

186. Phytother Res 2000 Jun;14(4):250-3

Application of flow injection--chemiluminescence to the study of radical scavenging activity in plants.

Choi HY, Jhun EJ, Lim BO, Chung IM, Kyung SH, Park DK

Department of Biochemistry, Konkuk University, Chungju, Chungbuk, Korea, 380-701.

Chemiluminescence (CL) was observed during the oxidation of luminol (2 mg/L). mediated by 0.06% hydrogen peroxide (H(2)O(2)) and cytochrome c (10 mg/L). CL intensity was decreased by the presence of radical scavengers and the reduction was linearly proportional to the concentration and ability of scavengers; butylated hydroxytoluene (BHT), caffeic acid and gallic acid. The order of effectiveness as radical scavengers was gallic acid > caffeic acid > BHT, which shows that the number of hydroxyl groups (OH) in the B-ring of flavonoids plays a key role in a good radical scavenging activity. Of eight catechins obtained from green tea extracts, (-)-catechin was the least effective and (-)-epigallocatechin gallate (EGCg) showed the strongest activity. This result indicates that the stereoscopic structure between the C-3 group and the B ring of flavonoids as well as substituents at the C-3 position make a contribution to radical scavenging activity. Of the tested Chinese herbal ingredients, five species of ingredients represented more than 90% of the radical scavenging activity.

187. Biofactors 2000;13(1-4):81-5

Tea catechins and related polyphenols as anti-cancer agents.

Isemura M, Saeki K, Kimura T, Hayakawa S, Minami T, Sazuka M

Laboratory of Cellular Biochemistry, Graduate School of Nutritional and Environmental Sciences, The University of Shizuoka, Japan.

[Medline record in process]

Epigallocatechin gallate (EGCg) and theaflavins, a major constituent of green tea infusion and the constituents of black tea, respectively, were found to inhibit matrix metalloproteinases (MMPs) which are intimately associated with tumor invasion and metastasis. EGCg and related polyphenols exhibited apoptosis-inducing activity for several cancer cell lines including human stomach and colon cancer cells. Comparison of the activity of these compounds revealed the importance of the number and the steric disposition of hydroxyl groups. A pyrogallol-type structure in a molecule is a minimum requirement for apoptosis induction of catechin compounds and that in the B ring has an important role in the activity. These data would provide useful information for designing anti-cancer agents on the basis of anti-inhibitory activity for MMPs and/or apoptosis-inducing activity.

188. FEBS Lett 2000 Apr 7;471(1):51-5

Green tea compounds inhibit tyrosine phosphorylation of PDGF beta-receptor and transformation of A172 human glioblastoma.

Sachinidis A, Seul C, Seewald S, Ahn H, Ko Y, Vetter H

Medizinische Universitats-Poliklinik, Wilhelmstr. 35-37, 53111, Bonn, Germany. sachinidis@uni-bonn.de

The effect of the green tea compounds 2-(3,4-dihydroxyphenyl)-3, 4-dihydro-2H-1-benzopyran-3,5,7-triol (catechin), epicathechin (EC), epigallocathechin-3 gallate (EGCG), epicathechin-3 gallate (ECG) and catechin-3 gallate (CG) on the tyrosine phosphorylation of PDGF beta-receptor (PDGF-Rbeta) and on the anchorage-independent growth of A172 glioblastoma cells in semisolid agar has been investigated. Treatment of A172 glioblastoma with 50 microM CG, ECG, EGCG and 25 microM Tyrphostin 1296 resulted in an 82+/-17%, 77+/-21%, 75+/-8% and 55+/-11%, respectively (mean+/-S.D., n=3) inhibition of the PDGF-BB-induced tyrosine phosphorylation of PDGF-Rbeta. The PDGF-Rbeta downstream intracellular transduction pathway including tyrosine phosphorylation of phospholipase C-gamma1 (PLC-gamma1) and phosphatidylinositol 3'-kinase (PI 3'-K) was also inhibited. Spheroid formation was completely inhibited by 50 microM ECG, CG, EGCG and by 25 microM Tyrphostin 1296. We conclude that catechins of the green tea possessing the gallate group in their chemical structure act as anticancer agents probably partly via their ability to suppress the tyrosine kinase activity of the PDGF-Rbeta.

189. Biochim Biophys Acta 2000 Mar 16;1478(1):51-60

Matrix metalloproteinase inhibition by green tea catechins.

Demeule M, Brossard M, Page M, Gingras D, Beliveau R

Laboratoire de Medecine Moleculaire, Hopital Sainte-Justine - UQAM, C.P. 8888, Succursale centre-ville, Montreal, QC, Canada.

We have investigated the effects of different biologically active components from natural products, including green tea polyphenols (GTP), resveratrol, genistein and organosulfur compounds from garlic, on matrix metalloproteinase (MMP)-2, MMP-9 and MMP-12 activities. GTP caused the strongest inhibition of the three enzymes, as measured by fluorescence assays using gelatin or elastin as substrates. The inhibition of MMP-2 and MMP-9 caused by GTP was confirmed by gelatin zymography and was observed for MMPs associated with both various rat tissues and human brain tumors (glioblastoma and pituitary tumors). The activities of MMPs were also measured in the presence of various catechins isolated from green tea including (-)-epigallocatechin gallate (EGCG), (-)-epicatechin gallate(ECG), (-)-epigallocatechin (EGC), (-)-epicatechin (EC) and (+)-catechin (C). The most potent inhibitors of these activities, as measured by fluorescence and by gelatin or casein zymography, were EGCG and ECG. GTP and the different catechins had no effect on pancreatic elastase, suggesting that the effects of these molecules on MMP activities are specific. Furthermore, in vitro activation of proMMP-2 secreted from the glioblastomas cell line U-87 by the lectin concanavalin A was completely inhibited by GTP and specifically by EGCG. These results indicate that catechins from green tea inhibit MMP activities and proMMP-2 activation.

190. Endocrinology 2000 Mar;141(3):980-7

Modulation of endocrine systems and food intake by green tea epigallocatechin gallate.

Kao YH, Hiipakka RA, Liao S

Ben May Institute for Cancer Research, Department of Biochemistry and Molecular Biology, and Tang Center for Herbal Medicine Research, University of Chicago, Illinois 60637, USA.

Green tea polyphenols, especially the catechin, (-)-epigallocatechin gallate (EGCG), have been proposed as a cancer chemopreventative based on a variety of laboratory studies. For clear assessment of the possible physiological effects of green tea consumption, we injected pure green tea catechins ip into rats and studied their acute effects on endocrine systems. We found that EGCG, but not related catechins, significantly reduced food intake; body weight; blood levels of testosterone, estradiol, leptin, insulin, insulin-like growth factor I, LH, glucose, cholesterol, and triglyceride; as well as growth of the prostate, uterus, and ovary. Similar effects were observed in lean and obese male Zucker rats, suggesting that the effect of EGCG was independent of an intact leptin receptor. EGCG may interact specifically with a component of a leptin-independent appetite control pathway. Endocrine changes induced by parenteral administration of EGCG may relate to the observed growth inhibition and regression of human prostate and breast tumors in athymic mice treated with EGCG as well as play a role in the mechanism by which EGCG inhibits cancer initiation and promotion in various animal models of cancer.

191. Eur J Clin Nutr 2000 Jan;54(1):87-92

A single dose of tea with or without milk increases plasma antioxidant activity in humans.

Leenen R, Roodenburg AJ, Tijburg LB, Wiseman SA

Unilever Nutrition Centre, Unilever Research Vlaardingen, PO Box 114, 3130 AC Vlaardingen, The Netherlands.

OBJECTIVE: To investigate the effect of black and green tea consumption, with and without milk, on the plasma antioxidant activity in humans. DESIGN: In a complete cross-over design, 21 healthy volunteers (10 male, 11 female) received a single dose of black tea, green tea (2 g tea solids in 300 ml water) or water with or without milk. Blood samples were obtained at baseline and at several time points up to 2 h post-tea drinking. Plasma was analysed for total catechins and antioxidant activity, using the ferric reducing ability of plasma (FRAP) assay. RESULTS: Consumption of black tea resulted in a significant increase in plasma antioxidant activity reaching maximal levels at about 60 min. A larger increase was observed after consumption of green tea. As anticipated from the higher catechin concentration in green tea, the rise in plasma total catechins was significantly higher after consumption of green tea when compared to black tea. Addition of milk to black or green tea did not affect the observed increases in plasma antioxidant activity. CONCLUSIONS: Consumption of a single dose of black or green tea induces a significant rise in plasma antioxidant activity in vivo. Addition of milk to tea does not abolish this increase. Whether the observed increases in plasma antioxidant activity after a single dose of tea prevent in vivo oxidative damage remains to be established. European Journal of Clinical Nutrition (2000) 54, 87-92

192. Food Chem Toxicol 2000 Jan;38(1):7-13

Inhibitory effects of tea extracts on the mutagenicity of 1-methyl-1, 2,3,4-tetrahydro-beta-carboline-3-carboxylic acid on treatment with nitrite in the presence of ethanol.

Higashimoto M, Akada Y, Sato M, Kinouchi T, Kuwahara T, Ohnishi Y

Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan.

It has been shown that the mutagenicity of 1-methyl-1,2,3, 4-tetrahydro-beta-carboline-3-carboxylic acid (MTCCA), a major mutagen precursor in soy sauce on treatment with nitrite and ethanol, was strongly decreased by the addition of hot water extracts of green, black and oolong teas in the reaction mixture when it was treated with 50mM nitrite at pH3.0, 37 degrees C for 60min in the presence of 7.5% ethanol. The mutagenicity-decreasing activity of the teas was scarcely decreased by washing the teas with chloroform and benzene and was partly decreased by butanol and ethyl acetate. Typical polyphenols such as catechins were shown to have the antimutagenicity dose dependently. The antimutagenicity and the reducing power of tea extracts gave a positive good correlation. The results suggest that the mutagenicity of MTCCA on treatment with nitrite in the presence of ethanol may be decreased by the mixed fractions of lyophilic components such as polyphenols, which have high reducing power such as catechins and the other compounds which have little reducing power including the derivatives of the catechins and so on. Although the antimutagenicity of teas and catechins was also considerably effective when they were added after the nitrosation, that of black tea and some catechins was less effective.

193.Atherosclerosis 2000 Jan;148(1):67-73

Inhibitory effect of Chinese green tea on endothelial cell-induced LDL oxidation.

Yang TT, Koo MW

Department of Pharmacology, Faculty of Medicine, The University of Hong Kong, 1/F Li Shu Fan Building, 5 Sassoon Road, Hong Kong.

Green tea has been shown to inhibit Cu(2+)-induced LDL oxidation and suppress lipoxygenase activity. Since LDL oxidation is a characteristic feature of atherogenesis and lipoxygenase is involved in the disease process, the effect of Lung Chen Tea, a non-fermented Chinese green tea, on LDL oxidation induced by human umbilical cord vascular endothelial cell was investigated in the present study. Lung Chen Tea was extracted with methanol and the dried powder was redissolved in water before extraction with chloroform and then ethyl acetate. Lung Chen Tea, chloroform and ethyl acetate fractions dose-dependently reduced LDL oxidation and decreased its relative electrophoretic mobility (P<0.001) when compared to the oxidized LDL. The lipid peroxidation products, thiobarbituric acid reactive substances, and cellular cholesterol were also significantly lowered by 5 and 10 microg/ml Lung Chen Tea (P<0.001) in a dose-dependent manner. The remaining aqueous layer, which was devoid of catechins after chloroform and ethyl acetate extractions, did not prevent LDL oxidation. The results of this study demonstrated that Lung Chen Tea and catechin-rich fractions significantly prevented endothelial cell induced LDL oxidation. The consumption of Lung Chen Tea may therefore lower the risk of coronary heart diseases.

194. Biofactors 2000;13(1-4):73-9

Mechanisms of inhibition of carcinogenesis by tea.

Yang CS, Chung JY, Yang GY, Li C, Meng X, Lee MJ

Laboratory Cancer Research, College of Pharmacy Rutgers, The State University of New Jersey, Piscataway 08854-8020, USA. csyang@rci.rutgers.edu

[Medline record in process]

Tea (Camellia sinensis) preparations have been shown to inhibit tumorigenesis at the initiation, promotion, and progression stages in different animal models. The anti-proliferative effects of tea polyphenols may be a key mechanism, especially in the NNK-induced lung tumorigenesis model with mice. Studies with cell lines have demonstrated that tea polyphenols inhibit cell proliferation and induce apoptosis. The effective concentrations used in these studies (20-100 microM) are usually higher than those observed in blood and tissues of humans and animals, which are in the low micromolar range. Glucuronide and sulfate conjugated and methylated catechins as well as ring fission products (due to intestinal microflora) have been observed in human plasma and urine. Purified green and black tea polyphenols inhibited the H-ras induced milogen-activated protein kinases, AP-1 activities, and the growth of 30.7b Ras 12 and BES21 cells. Among the catechins, both the galloyl structure on the B ring and the gallate moiety are important for the inhibition. Both (-)-epigallocatechin-3-gallate and theaflavin-3,3'-digallate inhibited the phosphorylation of c-jun and p44/42 (ERK 1/2). More mechanistic and human studies in these areas will help us to understand the possible inhibitory action of tea against carcinogenesis in humans.

195. Biofactors 2000;13(1-4):61-5

Regulation of intestinal glucose transport by tea catechins.

Shimizu M, Kobayashi Y, Suzuki M, Satsu H, Miyamoto Y

Department of Applied Biological Chemistry, The University of Tokyo, Japan.

[Medline record in process]

Intestinal glucose uptake is mainly performed by its specific transporters, such as SGLT 1, GLUT 2 and 5 expressed in the intestinal epithelial cells. By using human intestinal epithelial Caco-2 cells we observed that intestinal glucose uptake was markedly inhibited by tea extracts. While several substances in green tea seem to be involved in this inhibition, catechins play the major role and epicatechin gallate (ECg) showed the highest inhibitory activity. Since our Caco-2 cells did not express enough amount of SGLT 1, the most abundant intestinal glucose transporter, the effect of ECg on SGLT 1 was evaluated by using brush border membrane vesicles obtained from the rabbit small intestine. ECg inhibited SGLT 1 in a competitive manner, although ECg itself was not transported via the glucose transporters. These results suggest that tea catechins could play a role in controlling the dietary glucose uptake at the intestinal tract and possibly contribute to blood glucose homeostasis.

196. Biofactors 2000;13(1-4):55-9

Absorption, metabolism and antioxidative effects of tea catechin in humans.

Miyazawa T

Biodynamics Chemistry, Lab., Tohoku University Graduate School of Life Science & Agriculture, Sendai, Japan. miyazawa@biochem.tohoku.ac.jp

[Medline record in process]

Green tea is consumed as a popular beverage in Japan and throughout the world. During the past decade, epidemiological studies have shown that tea catechin intake is associated with lower risk of cardiovascular disease. In vitro biochemical studies have reported that catechins, particularly epigallocatechin-3-gallate (EGCg), help to prevent oxidation of plasma low-density lipoprotein (LDL). LDL oxidation has been recognized to be an important step in the formation of atherosclerotic plaques and subsequent cardiovascular disease. Metabolic studies have shown that EGCg supplement is incorporated into human plasma at a maximum concentration of 4400 pmol/mL. Such concentrations would be enough to exert antioxidative activity in the blood stream. The potent antioxidant property of tea catechin may be beneficial in preventing the oxidation of LDL. It is of interest to examine the effect of green tea catechin supplementation on antioxidant capacity of plasma in humans by measuring plasma phosphatidylcholine hydroperoxide (PCOOH) as a marker of oxidized lipoproteins.

197. Biofactors 2000;12(1-4):45-51

Role of diet modification in cancer prevention.

Abdulla M, Gruber P

Trace Element-Institute for UNESCO, Lyon, France.

[Medline record in process]

Carcinogenesis encompasses a prolonged accumulation of injuries at several different biological levels and include both genetic and biochemical changes in the cells. At each of these levels, there are several possibilities of intervention in order to prevent, slow down or even halt the gradual march of healthy cells towards malignancy. Diet modification is one such possibility. A number of natural foodstuffs, especially fruits and vegetables contain substantial quantities of molecules that have chemopreventive potential against cancer development. Such compounds include vitamins, trace elements and a variety of other molecules with antioxidant properties. Carotenoids, flavanoid polyphenols, isoflavones, catechins, and several other components that found in cruciferous vegetables are molecules that are known to protect against the deleterious effect of reactive oxygen species. A number of epidemiological and experimental studies have shown that vitamin C and E, Beta-carotene and the essential trace element selenium can reduce the risk of cancer. Consistent observations during the last few decades that cancer risk is reduced by a diet rich in vegetables, fruits, legumes, grains and green tea have encouraged research to identify several plant components especially phytochemicals that protect against DNA damage. Many of these substances block specific carcinogen pathways. Dietary supplements are part of an overall health program, along with a high intake of fruits and vegetables that help to combat damage to cells, which in turn may initiate cancer development. This paper will review current knowledge concerning diet modification and cancer prevention with special reference to minerals and trace elements.

198. J Mol Med 2000;78(6):333-6

Molecular mechanisms of anticancer activity of natural dietetic products.

Colic M, Pavelic K

R&D Division, Molecutec Corporation, Goleta, CA 93117, USA.

The efficiency of dietetic supplements in cancer prevention and treatment is a popular and controversial subject of research. New in vitro and in vivo research results indicate that some dietetic supplements do indeed show anticancer activity. The strongest anticancer action has been demonstrated by natural compounds with multifunctional activity. For instance, antioxidants, which also bind to and modulate the activity of protein kinases involved in signal transduction cascades show both cytostatic and cytotoxic activity towards cancer cells. Other activities such as angiogenesis inhibition, nitric oxide synthase inhibition, and pro-oxidants production have also been observed. catechins and polyphenols from plant extracts such as green tea show the strongest anticancer activity. The initial clinical trials with some flavonoid molecules are already underway.

199. Nutr Cancer 2000;37(1):41-8

Plasma and tissue levels of tea catechins in rats and mice during chronic consumption of green tea polyphenols.

Kim S, Lee MJ, Hong J, Li C, Smith TJ, Yang GY, Seril DN, Yang CS

Laboratory for Cancer Research, College of Pharmacy, Rutgers, State University of New Jersey, Piscataway 08854-8020, USA.

[Medline record in process]

To understand the relationship between tea consumption and its biological effects, plasma and tissue levels of (-)-epigallocatechin-3-gallate (EGCG), (-)-epigallocatechin (EGC), and (-)-epicatechin (EC) were measured after rats and mice were given a 0.6% green tea polyphenol preparation as the drinking fluid for different periods of time. EGC and EC levels in rat plasma increased over time and reached peak values (3 times the Day 1 values) on Day 14. Then the plasma levels of tea catechins decreased, to Day 1 values on Day 28. The plasma concentrations of EGCG were much lower than those of EGC or EC. High levels of EGC and EC were found in urine, whereas high levels of EGCG were found in feces. The changes in the urinary and fecal excretions of tea catechins could not account for the above-described changes in the plasma levels. The amounts of catechins in different tissues reflected the ingestion, absorption, and excretion pattern. When the green tea polyphenol preparation was given to mice, the "increase-and-then-decrease" pattern of catechin levels was also observed in the plasma, lung, and liver; the EGCG levels were much higher than in the rats. The results suggest that consumption of tea by rodents could induce adaptive responses affecting blood and tissue levels of tea catechins with time and that investigation of a similar phenomenon in humans is warranted.

200. J Nutr 1999 Dec;129(12):2130-4

Supplementation of Jurkat T cells with green tea extract decreases oxidative damage due to iron treatment.

Erba D, Riso P, Colombo A, Testolin G

Department of Food Science and Microbiology, Division of Human Nutrition, University of Milan, Milan, Italy.

Regular tea consumption has been associated with a reduced risk of cancer. As demonstrated in vitro, green tea contains catechins with antioxidant properties. We evaluated the effect of the supplementation of the Jurkat T-cell line with green tea extract on oxidative damage. Cells grown in medium with or without green tea extract (10 mg/L) were treated with Fe(2+) (100 &mgr;mol/L) as an oxidative stimulus for 2 h. Cell membrane lipid peroxidation was evaluated by fatty acids pattern analysis and malondialdehyde production in alpha-linolenic acid-loaded cells. Furthermore, oxidative DNA damage (single strand breaks) was detected in cells by the Comet assay and quantified as relative tail moment (RTM). Supplementation with green tea extract significantly decreased malondialdehyde production (1.6 +/- 0.3 vs. 0.6 +/- 0.1 nmol/mg protein, P < 0.05) and DNA damage (0.32 +/- 0.07 vs. 0.12 +/- 0.04 RTM, P < 0.05) after Fe(2+) oxidative treatment. In control cells, there was no effect on membrane distribution of (n-3) fatty acids due to Fe(2+) treatment. Cell enrichment with alpha-linolenic acid increased total membrane (n-3) fatty acids. However, the oxidative treatment did not modify the distribution of polyunsaturated fatty acids. It is likely that the observed protective effects can be attributed to epigallocatechin gallate, which is present mainly (670 g/kg) in green tea extract; however, we cannot exclude contributions by other catechins. These data support a protective effect of green tea against oxidative damage.

201. Thromb Res 1999 Nov 1;96(3):229-37

Antithrombotic activities of green tea catechins and (-)-epigallocatechin gallate.

Kang WS, Lim IH, Yuk DY, Chung KH, Park JB, Yoo HS, Yun YP

College of Pharmacy, Chungbuk National University, Cheongju, Korea.

The antithrombotic activities and mode of action of green tea catechins (GTC) and (-)-epigallocatechin gallate (EGCG), a major compound of GTC, were investigated. Effects of GTC and EGCG on the murine pulmonary thrombosis in vivo, human platelet aggregation in vitro, and ex vivo, and coagulation parameters were examined. GTC and EGCG prevented death caused by pulmonary thrombosis in mice in vivo in a dose-dependent manner. They significantly prolonged the mouse tail bleeding time of conscious mice. They inhibited adenosine diphosphate- and collagen-induced rat platelet aggregation ex vivo in a dose-dependent manner. GTC and EGCG inhibited ADP-, collagen-, epinephrine-, and calcium ionophore A23187-induced human platelet aggregation in vitro dose dependently. However, they did not change the coagulation parameters such as activated partial thromboplastin time, prothrombin time, and thrombin time using human citrated plasma. These results suggest that GTC and EGCG have the antithrombotic activities and the modes of antithrombotic action may be due to the antiplatelet activities, but not to anticoagulation activities.

202. J Pharm Pharmacol 1999 Nov;51(11):1325-31 Effects of green tea tannin on cisplatin-induced nephropathy in LLC-PK1 cells and rats. Yokozawa T, Nakagawa T, Lee KI, Cho EJ, Terasawa K, Takeuchi S. Research Institute for Wakan-Yaku, Toyama Medical and Pharmaceutical University, Sugitani, Japan. yokozawa@ms.toyama-mpu.ac.jp

A study was conducted to clarify whether green tea tannin ameliorated cisplatin-induced renal injury in terms of lactate dehydrogenase and malondialdehyde leakage from a renal epithelial cell line, swine-derived LLC-PK1 cells in culture. Green tea tannin was shown to suppress the cytotoxicity of cisplatin, the suppressive effect increasing with the dose of green tea tannin. The effect of cisplatin was then investigated in rats given green tea tannin for 40 days before cisplatin administration and in control rats given no green tea tannin. In control rats, blood, urinary and renal parameters and the activities of antioxidative enzymes in renal tissue deviated from the normal range, indicating dysfunction of the kidneys. In contrast, rats given green tea tannin showed decreased blood levels of urea nitrogen and creatinine, and decreased urinary levels of protein and glucose, reflecting less damage to the kidney. In this group, the activity of catalase in the renal tissue was increased, while the level of malondialdehyde was decreased, suggesting the involvement of radicals in the normalizing of kidney function. Based on the evidence available it appeared that green tea tannin eliminated oxidative stress and was beneficial to renal function.

203. Biochim Biophys Acta 1999 Oct 18;1472(1-2):42-50

Epigallocatechin gallate and gallocatechin gallate in green tea catechins inhibit extracellular release of Vero toxin from enterohemorrhagic Escherichia coli O157:H7.

Sugita-Konishi Y, Hara-Kudo Y, Amano F, Okubo T, Aoi N, Iwaki M, Kumagai S

Department of Biomedical Food Research, National Institute of Infectious Diseases, Toyama, Tokyo, Japan. ykonishi@nih.go.jp

We studied the effects of six catechin derivatives (catechin, epigallocatechin, epicatechin, epicatechin gallate, epigallocatechin gallate (EGCg) and gallocatechin gallate (GCg)) in green tea on the production and extracellular release of Vero toxins (VTs) from enterohemorrhagic Escherichia coli (EHEC) cultured at 37 degrees C for 24 h. EGCg and GCg in the culture medium markedly inhibited extracellular VTs release from EHEC cells into the culture supernatant fluid at concentrations of 0.05 mg/ml or higher, as estimated by both the reversed passive latex agglutination assay and cytotoxic assay using Vero cells. Production and extracellular release of maltose binding protein, a periplasmic protein, into the culture supernatant were also inhibited by EGCg and GCg, indicating that their inhibitory effect on release from periplasm into the outer milieu is not specific to VTs, but general to the proteins accumulated in EHEC periplasm.

204. Altern Med Rev 1999 Oct;4(5):360-70

Green tea (Camellia sinensis) extract and its possible role in the prevention of cancer.

Brown MD

Sage Health Clinic, Bend, OR, USA. drcowboyup@hotmail.com

The American Cancer Society estimates that in the 1980s more than 4. 5 million Americans died of cancer. In addition, there were nearly nine million new cases and about 12 million people were under medical care for cancer. With cancer being the second most common cause of death in the United States population, the possibility that readily-available natural substances may be beneficial in the prevention of cancer warrants closer examination. A growing body of research has demonstrated green tea polyphenols to be powerful antioxidants with anticarcinogenic properties. These polyphenolic compounds, specifically the catechins epigallocatechin-3-gallate (EGCG), epigallocatechin (EGC), and epicatechin-3-gallate (ECG), which account for 30-40 percent of the extractable solids of green tea leaves, are believed to mediate many of the cancer chemopreventive effects. Mechanisms of action may include antioxidant and free-radical scavenging activity, and stimulation of detoxification systems through selective induction or modification of phase I and phase II metabolic enzymes. In addition, green tea may inhibit biochemical markers of tumor initiation and promotion, including the rate of cell replication and thus inhibition of the growth and development of neoplasms. Current studies are hopeful, as they show an inverse association between green tea consumption and cancer risk, supporting a possible chemopreventive effect of green tea. Based on the knowledge that green tea is inexpensive, non-toxic, and is a popular beverage consumed worldwide, clinical trials should be conducted to evaluate the in-vivo effectiveness of green tea polyphenols on the inhibition and chemopreventive treatment of cancer.

205. J Agric Food Chem 1999 Oct;47(10):3967-73

Tea catechin supplementation increases antioxidant capacity and prevents phospholipid hydroperoxidation in plasma of humans.

Nakagawa K, Ninomiya M, Okubo T, Aoi N, Juneja LR, Kim M, Yamanaka K, Miyazawa T

Laboratory of Biodynamic Chemistry, Tohoku University Graduate School of Life Science and Agriculture, Sendai 981-8555, Japan.

The effect of green tea catechin supplementation on antioxidant capacity of human plasma was investigated. Eighteen healthy male volunteers who orally ingested green tea extract (254 mg of total catechins/subject) showed 267 pmol of epigallocatechin-3-gallate (EGCg) per milliliter of plasma at 60 min after administration. The plasma phosphatidylcholine hydroperoxide (PCOOH) levels attenuated from 73.7 pmol/mL in the control to 44.6 pmol/mL in catechin-treated subjects, being correlated inversely with the increase in plasma EGCg level. The results suggested that drinking green tea contributes to prevent cardiovascular disease by increasing plasma antioxidant capacity in humans.

206. ood Chem Toxicol 1999 Sep-Oct;37(9-10):985-92

Phenolics: blocking agents for heterocyclic amine-induced carcinogenesis.

Hirose M, Takahashi S, Ogawa K, Futakuchi M, Shirai T

First Department of Pathology, Nagoya City University, Medical School, Nagoya, Japan.

Chemopreventive effects of synthetic and naturally occurring antioxidants on heterocyclic amine (HCA)-induced rat carcinogenesis and mechanisms of inhibition were assessed. In a medium-term liver bioassay, combined treatment with 0.03% 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and synthetic antioxidants such as 1-O-hexyl-2,3,5-trimethylhydroquinone (HTHQ), butylated hydroxyanisole (BHA), butylated hydroxutoluene (BHT), tert-butylhydroquinone (TBHQ) or propyl gallate, each at a dose of 0.25%, inhibited development of preneoplastic glutathione S-transferase placental form (GST-P) positive foci as compared with MeIQx alone, after initiation with diethylnitrosamine (DEN). Of these antioxidants, HTHQ showed the greatest activity. 8-Hydroxydeoxyguanosine (8-OHdG), a marker for DNA damage induced by active oxygen species, and malonedialdehyde and 4-hydroxynonenal levels were not largely influenced by the treatment with MeIQx or antioxidants, either alone or in combination. In the same medium-term liver bioassay, effects of some naturally occurring antioxidants, such as green tea catechins (GTC), hesperidin, chlorogenic acid, quercetin, rutin, curcumin, daidzin, ferulic acid and genistein were also examined. Of these antioxidants, only GTC tended to inhibit GST-P positive foci development, while quercetin, rutin, curcumin, daidzin, ferulic acid and genistein all exerted significant enhancing effects. Examination of HTHQ influence in a medium term liver bioassay with HCA Glu-P-1, in which the experimental period was extended for up to 26 weeks, also demonstrated a significant decrease in the incidence of liver tumours to 40% in the group treated with 0.5% HTHQ and 0.03% 2-amino-6-methyldipyrido[1,2-a:3',2'-d]imidazole (Glu-P-1) as compared with the Glu-P-1 alone value of 89%. Effects of HTHQ on colon carcinogenesis induced by 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) were evaluated in a two-stage colon carcinogenesis model using 1,2-dimethylhydrazine (DMH) as an initiator. At week 36, the multiplicity of colon tumours induced by 0.02% PhIP after DMH initiation (9.1+/-6.2/rat) was dose-dependently decreased by the combined treatment with 0.5% HTHQ (3.6+/-1.8, P < 0.001) and 0.125% HTHQ (6.2+/-3.2, not significant). Similarly, the incidence of mammary carcinomas in female F344 rats induced by oral administration of 0.02% PhIP (40%) for 52 weeks was significantly decreased by simultaneous treatment with 0.5% HTHQ (5%). Alpha-tocopherol and chlorophyllin only reduced the multiplicity of carcinomas. Analysis of the influence of HTHQ on metabolic activation of Glu-P-1 or PhIP after incubation with rat S9 mixture and NADPH by HPLC, revealed that each major metabolite was strongly reduced by the addition of HTHQ. Immunohistochemically detected PhIP-DNA adduct positive nuclei in the colon induced by continuous oral treatment with 0.02% PhIP for 2 weeks decreased by the combined treatment with 0.5 or 0.125% HTHQ. These results indicate that synthetic antioxidant HTHQ is a very strong chemopreventor of heterocyclic amine (HCA)-induced carcinogenesis and that depressed metabolic activation rather than antioxidant activity is responsible for the observed effect.

207. Toxicol Lett 1999 Sep 20;109(1-2):69-76 Proliferation of hepatic peroxisomes in rats following the intake of green or black tea. Bu-Abbas A, Dobrota M, Copeland E, Clifford MN, Walker R, Ioannides C. School of Biological Sciences, University of Surrey, Guildford, UK.

Rats maintained on green, black or decaffeinated black tea (2.5%, w/v) as their sole drinking fluid displayed higher hepatic CN- insensitive palmitoyl CoA oxidase activity than controls; the extent of increase was similar with the three types of tea. Morphological examination of the liver using electron microscopy revealed an increase in the number of peroxisomes in the tea-treated animals. The same treatment of the animals with green and black tea resulted in a similar rise in hepatic microsomal lauric acid hydroxylation. Analysis by HPLC of the aqueous tea extracts employed in the current study showed that the total flavanol content of the green variety was much higher than the black varieties, and confirmed the absence of caffeine in the decaffeinated black tea. It may be concluded from the present studies that neither caffeine nor flavanoids are likely to be responsible for the proliferation of peroxisomes observed in rats treated with tea.

208. Cancer Res 1999 Sep 15;59(18):4610-7

Inhibition of activator protein 1 activity and cell growth by purified green tea and black tea polyphenols in H-ras-transformed cells: structure-activity relationship and mechanisms involved.

Chung JY, Huang C, Meng X, Dong Z, Yang CS

Laboratory for Cancer Research, College of Pharmacy, Rutgers, The State University of New Jersey, Piscataway 08854, USA.

ras gene mutation, which perpetually turns on the growth signal transduction pathway, occurs frequently in many cancer types. The mouse epidermal JB6 cell line has been transfected with a mutant H-ras gene to mimic carcinogenesis in vitro. These transformed cells (30.7b Ras 12) are able to grow in soft agar, exhibiting anchorage independence and high endogenous activator protein 1 (AP-1) activity, which can be detected by a stable AP-1 luciferase reporter. The present study investigated the ability of different pure green and black tea polyphenols to inhibit this ras signaling pathway. The major green tea polyphenols (catechins), (-)-epigallocatechin-3-gallate (EGCG), (-)-epigallocatechin, (-)-epicatechin-3-gallate, (-)-epicatechin, and their epimers, and black tea polyphenols, theaflavin, theaflavin-3-gallate, theaflavin-3'-gallate, and theaflavin-3,3'-digallate (TFdiG), were compared with respect to their ability to inhibit the growth of 30.7b Ras 12 cells and AP-1 activity. All of the tea polyphenols except (-)-epicatechin showed strong inhibition of cell growth and AP-1 activity. Among the catechins, both the galloyl structure on the B ring and the gallate moiety contributed to the growth inhibition and AP-1 activity; the galloyl structure appeared to have a stronger effect on the inhibitory action than the gallate moiety. The epimers of the catechins showed similar inhibitory effects on AP-1 activity. The addition of catalase to the incubation of the cells with EGCG or TFdiG did not prevent the inhibitory effect on AP-1 activity, suggesting that H2O2 does not play a significant role in the inhibition by tea polyphenols. Both EGCG and TFdiG inhibited the phosphorylation of p44/42 (extracellular signal-regulated kinase 1 and 2) and c-jun without affecting the levels of phosphorylated-c-jun-NH2-terminal kinase. TFdiG inhibited the phosphorylation of p38, but EGCG did not. EGCG lowered the level of c-jun, whereas TFdiG decreased the level of fra-1. These results suggest that tea polyphenols inhibited AP-1 activity and the mitogen-activated protein kinase pathway, which contributed to the growth inhibition; however, different mechanisms may be involved in the inhibition by catechins and theaflavins.

209. Cancer Lett 1999 Sep 1;143(2):179-83

Chemoprevention studies of heterocyclic amine-induced colon carcinogenesis.

Xu M, Dashwood RH

The Linus Pauling Institute, and Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis 97331-6512, USA.

The cooking of meat and fish produces heterocyclic amine mutagens, including 2-amino-1-methyl-6-phenylimidazo[4,5b]pyridine (PhIP) and 2-amino-3-methylimidazo[4,5-f]quinoline (IQ). Chronic administration of PhIP or IQ to the F344 rat induces tumors at several sites, including adenocarcinomas of the colon, and short-term treatment leads to the formation of colonic aberrant crypt foci (ACF). We have used these end-points to identify potential chemopreventive agents that might be effective against heterocyclic amine colon carcinogens. Typically, IQ or PhIP were administered to groups of 10-15 rats by oral gavage on alternating days in weeks 3 and 4, and ACF were scored after 8, 12, or 16 weeks or tumors were detected at 52 weeks. To distinguish between 'blocking' and 'suppressing' agents, potential inhibitors were administered during the initiation or post-initiation phases, respectively, and subsequent studies focused on the inhibitory mechanisms. Among the most effective inhibitors identified to date, and their major mechanisms, were the following: chlorophyllin (molecular complex formation); indole-3-carbinol (inhibition and induction of cytochromes P450 and phase II enzymes); green and black tea catechins (induction of UDP-glucuronosyl transferase, inhibition of NADPH-cytochrome P450 reductase, scavenging of reactive intermediates); and conjugated linoleic acids (inhibition of cytochrome P450 and prostaglandin H synthase).

210. Pharmacology 1999 Jul;59(1):34-44

Effects of green tea catechins on membrane fluidity.

Tsuchiya H

Department of Dental Pharmacology, Asahi University School of Dentistry, Hozumi, Gifu, Japan. hiro@dent.asahi-u.ac.jp

Catechins originating from green tea have been used in plaque inhibition for caries prevention and treatment for liver damage because of their antibacterial activity against cariogenic bacteria and protective activity on hepatic cells. The effects of catechins on membrane fluidity were studied by a fluorescence polarization method using liposomes prepared with dipalmitoylphosphatidylcholine and dioleoylphosphatidylcholine to assess their pharmacological mechanism at micromol/l levels found in human body fluids after clinical application. All eight catechins tested, ranging from 1 to 1,000 micromol/l, significantly reduced membrane fluidity in both hydrophilic and hydrophobic regions of lipid bilayers. catechin gallate esters were superior in fluidity reduction to the corresponding nonesters. The fluidity-reducing degree was different between the cis and trans forms, suggesting the stereospecific activity of catechins. A reference antiplaque agent, chlorhexidine, similarly reduced membrane fluidity at the antibacterial concentration. (+)-Catechin (250 micromol/l) and (-)-epigallocatechin gallate (2.5 micromol/l) significantly prevented the membrane fluidization induced by hepatotoxic chloroform. These results indicate that the reduction in membrane fluidity is responsible for the antiplaque and hepatoprotective effects of green tea catechins.

211. Eur J Nutr 1999 Jun;38(3):149-57

Green tea extract decreases plasma malondialdehyde concentration but does not affect other indicators of oxidative stress, nitric oxide production, or hemostatic factors during a high-linoleic acid diet in healthy females.

Freese R, Basu S, Hietanen E, Nair J, Nakachi K, Bartsch H, Mutanen M

Division of Nutrition, University of Helsinki, Finland. riitta.freese@helsinki.fi

BACKGROUND: green tea contains polyphenolic catechins which can act as antioxidants and thus decrease the risk for cardiovascular diseases. AIM OF THE STUDY: To investigate whether green tea extract differs from placebo in its effects on markers of antioxidant status, lipid peroxidation, nitric oxide production, thromboxane production, and blood coagulation during a controlled high linoleic acid diet in healthy subjects. METHODS: Twenty healthy non-smoking females (23-50 years) participated in a 4-week controlled intervention study. The experimental diet was rich in linoleic acid (9 en%) and contained fat, protein, and carbohydrates: 27, 14, and 59 en%, respectively. In addition, the subjects ingested encapsulated green tea extract (3 g/d) or placebo mixture in a double-blind manner. Fasting blood samples and five 24-hour urines were collected before and at the end of the 4-week experimental period. Same samples were received from 10 control subjects. RESULTS: green tea extract significantly decreased plasma malondialdehyde (MDA) concentration in comparison with the placebo treatment. The treatments did not differ in serum lipids, indicators of antioxidant status, urinary 8-isoprostaglandin F2 alpha, 2,3-dinorthromboxane B2, nitric oxide metabolites or coagulation indicators. CONCLUSIONS: We conclude that an amount of green tea extract which corresponds to 10 cups of tea per day for 4 weeks does not have specific effects on several indicators related to risk of cardiovascular diseases in comparison with placebo treatment. The relatively small but significant decrease in lipid peroxidation indicated by decreased plasma MDA was not associated with changes in markers of oxidative stress (urinary 8-isoprostaglandin F2 alpha and blood oxidized glutathione) or hemostasis.

212, J Agric Food Chem 1999 May;47(5):2020-5

Regeneration of alpha-tocopherol in human low-density lipoprotein by green tea catechin.

Zhu QY, Huang Y, Tsang D, Chen ZY

Departments of Biochemistry and Physiology, The Chinese University of Hong Kong, Shatin, Hong Kong.

Oxidative modification of low-density lipoproteins (LDL) may play an important role in the development of atherosclerosis. alpha-Tocopherol functions as a major antioxidant in human LDL. The present study was to test whether green tea catechins (GTC) would protect or regenerate alpha-tocopherol in human LDL. The oxidation of LDL incubated in sodium phosphate buffer (pH 7.4, 10 mM) was initiated by addition of 1.0 mM of 2,2'-azobis(2-amidinopropane) dihydrochloride at 40 degrees C. It was found that alpha-tocopherol was completely depleted within 1 h. Under the same experimental conditions, the longjing GTC extracts demonstrated a dose-dependent protective activity to alpha-tocopherol in LDL at concentrations ranging from 2 to 20 microM. Four pure epicatechin derivatives showed varying protective activity against depletion of alpha-tocopherol in LDL with (-)-epigallocatechin (EGC) and (-)-epigallocatechin gallate (EGCG) being less effective than (-)-epicatechin (EC) and (-)-epicatechin gallate (ECG). The results showed that addition of longjing GTC extracts, EC, ECG, and EGCG at 5, 10, and 15 min to the incubation mixture demonstrated a gradual regeneration of alpha-tocopherol in human LDL.

213. Chem Res Toxicol 1999 Apr;12(4):382-6

Antioxidant chemistry of green tea catechins. Identification of products of the reaction of (-)-epigallocatechin gallate with peroxyl radicals.

Valcic S, Muders A, Jacobsen NE, Liebler DC, Timmermann BN

Department of Pharmacology & Toxicology, College of Pharmacy, The University of Arizona, Tucson, Arizona 85721, USA.

(-)-Epigallocatechin gallate (EGCG), isolated from green tea, displays antioxidant properties and is thought to act as an antioxidant in biological systems. However, the specific mechanisms of its antioxidant actions remain unclear. In this study, we have isolated and identified for the first time two reaction products of EGCG derived from its reaction with peroxyl radicals generated by thermolysis of the initiator 2,2'-azobis(2,4-dimethylvaleronitrile) (AMVN). The products include a seven-membered B-ring anhydride and a novel dimer. The identification of these products provides the first unambiguous proof that the principal site of antioxidant reactions on the EGCG molecule is the trihydroxyphenyl B ring, rather than the 3-galloyl moiety. In contrast to phenoxyl radicals from simple phenolic antioxidants, an initially formed EGCG phenoxyl radical apparently does not form stable addition products with AMVN-derived peroxyl radicals. Characteristic reaction products may provide novel markers for EGCG antioxidant reactions in living systems.

214. Proc Soc Exp Biol Med 1999 Apr;220(4):239-43

Cancer chemopreventive mechanisms of tea against heterocyclic amine mutagens from cooked meat.

Dashwood RH, Xu M, Hernaez JF, Hasaniya N, Youn K, Razzuk A

The Linus Pauling Institute, and Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, Oregon 97331-6512, USA.Rod.Dashwood@orst.edu

Cooking meat and fish under normal conditions produces heterocyclic amine mutagens, several of which have been shown to induce colon tumors in experimental animals. In our search for natural dietary components that might protect against these mutagens, it was found that green tea and black tea inhibit the formation of heterocyclic amine-induced colonic aberrant crypt foci (ACF) in the rat. Since ACF are considered to be putative preneoplastic lesions, we examined the inhibitory mechanisms of tea against the heterocyclic amines. In the initial studies using the Salmonella mutagenicity assay, green tea and black tea inhibited according to the concentration of tea leaves during brewing and the time of brewing; a 2-3-min brew of 5% green tea (w/v) was sufficient for >90% antimutagenic activity. N-hydroxylated heterocyclic amines, which are direct-acting mutagens in Salmonella, were inhibited by complete tea beverage and by individual components of tea, such as epigallocatechin-3-gallate (EGCG). Inhibition did not involve enhanced mutagen degradation, and EGCG and other catechins complexed only weakly with the mutagens, suggesting electrophile scavenging as an alternative mechanism. Enzymes that contribute to the metabolic activation of heterocyclic amines, namely microsomal NADPH-cytochrome P450 reductase and N, O-acetyltransferase, were inhibited by tea in vitro. Studies in vivo established that tea also induces cytochromes P450 and Phase II enzymes in a manner consistent with the rapid metabolism and excretion of heterocyclic amines. Collectively, the results indicate that tea possesses anticarcinogenic activity in the colon, and this most likely involves multiple inhibitory mechanisms.

215. Proc Soc Exp Biol Med 1999 Apr;220(4):203-9

Plasma and lipoprotein levels of tea catechins following repeated tea consumption.

van het Hof KH, Wiseman SA, Yang CS, Tijburg LB

Unilever Research Vlaardingen, 3130 AC Vlaardingen, The Netherlands. karin-van-het.hof@unilever.com

Epidemiological studies suggest that antioxidant flavonoids in tea may reduce the risk of cardiovascular disease, possibly via protection of low-density lipoproteins (LDL) against oxidation. However, the extent of absorption of tea flavonoids and their accumulation in LDL during regular consumption of tea is not clear. Therefore we investigated plasma and lipoprotein levels of catechins during tea consumption and the impact on LDL oxidizability ex vivo. Eighteen healthy adults consumed, in an incomplete balanced cross-over design, green tea, black tea, black tea with milk or water, one cup every 2 hr (eight cups/day) for three days. Blood samples were obtained in the mornings and evenings of each day. Plasma total catechin concentration was determined in all blood samples, and the distribution of catechins among lipoproteins was determined at the end of the third day (t = 60 hr). The resistance of LDL to copper-induced oxidation ex vivo was assessed before tea consumption and at t = 60 hr. Repeated tea consumption during the day rapidly increased plasma total catechin levels whereas they declined overnight when no tea was consumed. There was a gradual increase in plasma levels in the mornings (respectively, 0.08 microM vs. 0.20 microM on first and last day of black tea consumption) and evenings (respectively, 0.29 microM vs. 0.34 microM on first and last day of black tea consumption). green tea catechins were mainly found in the protein-rich fraction of plasma (60%) and in high-density lipoproteins (23%). Although present in LDL, the concentration of catechins in LDL was not sufficient to enhance the resistance of LDL to oxidation ex vivo. Addition of milk to black tea did not affect any of the parameters measured. In conclusion, the present study shows that catechin levels in blood rapidly increase upon repeated tea consumption. The accumulation of catechins in LDL particles is not sufficient to improve the intrinsic resistance of LDL to oxidation ex vivo.

216. Cancer Lett 1999 Feb 8;136(1):79-82

Effect of polyphenon-60 on the development of renal cell tumors in rats treated with N-ethyl-N hydroxyethylnitrosamine.

Yoshioka N, Hiasa Y, Cho M, Kitahori Y, Hirao K, Konishi N, Kuwashima S

Department of Pathology, Nara Medical University, Kashihara, Japan.

Green tea consumed as a beverage in Asia contains polyphenols, which contain about a 15% mixture of catechins. The present paper reports the effect of polyphenon-60 (60% pure catechin) on the development of renal cell neoplasms in Wistar rats pretreated with N-ethyl-N-hydroxyethylnitrosamine (EHEN): 0.1% polyphenon-60 in block diet was given over a period of 30 weeks while EHEN was given in drinking water for 2 weeks. The results appears to show a tendency for green tea catechins (GTC) to decrease the incidence of renal cell tumors greater than 3 mm in diameter in Wistar rats but not tumors that are less than 3 mm in diameter. Polyphenon-60 did not affect EHEN initiation in the kidneys of rats. It is postulated that free radicals induced by EHEN may be suppressed by GTC, resulting in a lowering of the tendency for tumor growth.

217. Cancer Epidemiol Biomarkers Prev 1999 Jan;8(1):83-9

Human salivary tea catechin levels and catechin esterase activities: implication in human cancer prevention studies.

Yang CS, Lee MJ, Chen L

College of Pharmacy, Rutgers, The State University of New Jersey, Piscataway 08854-8020, USA.

Because of the possible application of tea in the prevention of oral and esophageal cancers, the salivary levels of tea catechins were determined in six human volunteers after drinking tea. Saliva samples were collected after thoroughly rinsing the mouth with water. After drinking green tea preparations equivalent to two to three cups of tea, peak saliva levels of (-)-epigallocatechin (EGC; 11.7-43.9 microg/ml), EGC-3-gallate (EGCG; 4.8-22 microg/ml), and (-)-epicatechin (EC; 1.8-7.5 microg/ml) were observed after a few minutes. These levels were 2 orders of magnitude higher than those in the plasma. The elimination half-life (t(1/2)) of the salivary catechins was 10-20 min, much shorter than that of the plasma. Holding a tea solution in the mouth for a few minutes without swallowing produced even higher salivary catechin levels, but taking tea solids in capsules resulted in no detectable salivary catechin level. Holding an EGCG solution in the mouth resulted in EGCG and EGC in the saliva and, subsequently, EGC in the urine. The results suggest that EGCG was converted to EGC in the oral cavity, and both catechins were absorbed through the oral mucosa. A catechin esterase activity that converts EGCG to EGC was found in the saliva. The enzyme was likely of human origin, but the activity was not inhibited by common human esterase inhibitor. The present results suggest that slowly drinking tea is a very effective way of delivering rather high concentrations of catechins to the oral cavity and then the esophagus.

218. Life Sci 1999;65(21):PL241-6

Inhibition of tyrosinase by green tea components.

No JK, Soung DY, Kim YJ, Shim KH, Jun YS, Rhee SH, Yokozawa T, Chung HY

College of Pharmacy, Research Institute of Drug Development, Pusan National University, Kumjung-Gu, Korea.

The pigment melanin in human skin is a major defense mechanism against ultraviolet light of the sun, but darkened skin color, which is the result of increased and redistributed epidermal melanin, could be a serious aesthetic problem. Epidemiologically, it is well known that the consumption of green tea may help prevent cancers in humans and also reduce several free radicals including peroxynitrite. In the present study, to assess the efficacy of the inhibition of mushroom tyrosinase (monophenol monooxygenase EC 1.14.18.1), ten kinds of Korean traditional teas were screened for their tyrosinase inhibitory activity. green tea was the strongest inhibitor, and the major active constituents in the tea are (-)-epicatechin 3-O-gallate (ECG), (-)-gallocatechin 3-O-gallate (GCG), and (-)-epigallocatechin 3-O-gallate (EGCG). All are catechins with gallic acid group as an active site. The kinetic analysis for inhibition of tyrosinase revealed a competitive nature of GCG with this enzyme for the L-tyrosine binding at the active site of tyrosinase.

219. Carcinogenesis 1998 Dec;19(12):2201-4

(-)-Epigallocatechin-3-gallate inhibition of ultraviolet B-induced AP-1 activity.

Barthelman M, Bair WB, Stickland KK, Chen W, Timmermann BN, Valcic S, Dong Z, Bowden GT

Department of Radiation Oncology, University of Arizona Health Sciences Center, Tucson 85724, USA.

Green tea polyphenols have been shown to inhibit cancer in a variety of tumor models, including ultraviolet B (UVB)-induced non-melanoma skin cancer. In green tea extracts, the major dry mass constituent is the family of catechins, of which (-)-epigallocatechin-(3)-gallate (EGCG) is considered to be important for the chemopreventive activity. EGCG has been shown to have antioxidant properties, but there has been little progress toward identifying the specific targets and mechanisms of its action. Using cultured human keratinocytes, we show that UVB-induced AP-1 activity is inhibited by EGCG in a dose range of 5.45 nM to 54.5 microM. EGCG is effective at inhibiting AP-1 activity when applied before, after or both before and after UVB irradiation. EGCG also inhibits AP-1 activity in the epidermis of a transgenic mouse model. This work begins to define a mechanism by which EGCG could be acting to inhibit UVB-induced tumor formation.

220. Biochem Mol Biol Int 1998 Dec;46(5):895-903

Relationship between rate and extent of catechin absorption and plasma antioxidant status.

Pietta P, Simonetti P, Gardana C, Brusamolino A, Morazzoni P, Bombardelli E

ITBA-CNR, Milan, Italy.

Flavonoids are described to exert a large array of biological activities, which are mostly ascribed to their radical-scavenging, metal chelating and enzyme modulation ability. Most of these evidences have been obtained by in vitro studies on individual compounds and at doses largely exceeding those dietary. Little is known about a possible relationship between rate and extent of the absorption and modifications of plasma antioxidants. To elucidate this aspect, human volunteers were supplemented with single doses of green tea catechins in free (Greenselect) or phospholipid complex form (Greenselect Phytosome) equivalent to 400 mg epigallocatechingallate (EGCg). EGCg was chosen as biomarker for green tea catechin absorption, and its time course plasma concentration was correlated to the subsequent percent variations of plasma ascorbate, total glutathione, alpha-tocopherol, beta-carotene and Total Radical Antioxidant Parameter (TRAP). green tea catechins were absorbed more extensively when administered as phospholipid complex rather than as free catechins. Single dose intake of both forms of catechins produced a transient decrease (10-20%) of plasma ascorbate and total glutathione and an increase of plasma TRAP (16-19%). These variations were consistent with the plasmatic levels of EGCg, ascorbate and total glutathione.

221. Chem Biol Interact 1998 Jul 3;114(1-2):109-19

Inhibition of linoleic acid hydroperoxide-induced toxicity in cultured human umbilical vein endothelial cells by catechins.

Kaneko T, Matsuo M, Baba N

Laboratory of Biochemistry and Isotopes, Tokyo Metropolitan Institute of Gerontology, Japan. kaneko@center.tmig.or.jp

The protective effect of catechins, major components of green tea, was studied in cultured human umbilical vein endothelial cells exposed to toxicity induced by linoleic acid hydroperoxide (LOOH). In the case where cells were incubated in medium containing both LOOH and catechins, (+)-catechin (C) was effective in suppressing of LOOH-induced cytotoxicity, but (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), and (-)-epigallocatechin gallate (EGCG) had no effect. EGCG monoglucoside (EGCG-G1) and EGCG diglucoside (EGCG-G2), apophilic derivatives of EGCG, show a protective effect on LOOH-induced cytotoxicity when present at the time of treatment with LOOH. On the other hand, when cells were incubated with catechins for 24 h before treatment with LOOH there was no protection against the oxidative damage by LOOH. Furthermore, the interaction between catechins and alpha-tocopherol was examined under these culture conditions. C showed a synergistic effect with alpha-tocopherol in protecting against LOOH-induced damage. These results suggest that catechins interact with LOOH present in the medium or near the surface of membranes, but not with LOOH incorporated into cellular membranes and that catechins are able to interact with alpha-tocopherol to provide synergistic protection against the cytotoxicity of LOOH.

222. Br J Pharmacol 1998 Jul;124(6):1227-37

Epigallocatechin suppression of proliferation of vascular smooth muscle cells: correlation with c-jun and JNK.

Lu LH, Lee SS, Huang HC

Department of Pharmacology, College of Medicine, National Taiwan University, Taipei.

1. The mechanisms of the antiproliferative effect of epigallocatechin, one of the catechin derivatives found in green tea, in vascular smooth muscle cells were studied. The proliferative response was determined from the uptake of tritiated thymidine. 2. In the concentration range of 10(-6) to 10(-4) M, catechin, epicatechin, epigallocatechin, epicatechin gallate and epigallocatechin, epigallocatechin gallate, concentration-dependently inhibited the proliferative response stimulated by serum in rabbit cultured vascular smooth muscle cells. catechin and epicatechin were less effective in inhibiting the serum-stimulated smooth muscle cell proliferation, indicating that the galloyl group may be important for full inhibitory activity. 3. Epigallocatechin (EGC) inhibited the proliferative responses in different cells including rat aortic smooth muscle cells (A7r5 cells), rabbit cultured aortic smooth muscle cells, human coronary artery smooth muscle cells, and human CEM lymphocytes in a concentration-dependent manner. The possible mechanisms of the antiproliferative effect of EGC were further studied in A7r5 cells. 4. The membranous protein tyrosine kinase activity stimulated by serum in A7r5 cells was significantly reduced by 10(-5) M EGC. In contrast, the cytosolic protein kinase C activity stimulated by phorbol ester was unaffected by directly incubating with EGC (10(-6)-10(-4) M). 5. We also performed Western blot analysis using the anti-phosphotyrosine monoclonal antibody PY20. EGC (10(-5) M) reduced the levels of tyrosine phosphorylated proteins with different molecular weights, indicating that EGC may inhibit the protein tyrosine kinase activity or stimulate the protein phosphatase activity. 6. Reverse transcription-polymerase chain reaction analysis of c-fos, c-jun and c-myc mRNA levels demonstrated that c-jun mRNA level after serum-stimulation was significantly reduced by 10(-5) M EGC. However, the reduction of c-fos and c-myc mRNA levels by 10(-5) M EGC did not achieve significance. 7. Western blot analysis using the antibody against JNK (c-jun N-terminal kinase) and ERK (extracellular signal-regulated kinase) demonstrated that the level of phosphorylated JNK1, but not phosphorylated ERK1 and ERK2, was reduced by 10(-5) M EGC. Direct measurement of kinase activity by immune complex kinase assay confirmed that JNK1 activity was inhibited by EGC treatment. These results demonstrate that EGC preferentially reduced the activation of JNK/SAPK (stress-activated protein kinase) signal transduction pathway. 8. It is suggested that the antiproliferative effect of epigallocatechin on vascular smooth muscle cells may partly be mediated through inhibition of protein tyrosine kinase activity, reducing c-jun mRNA expression and inhibiting JNK1 activation. Tea catechins may be useful as a template for the development of drugs to prevent the pathological changes of atherosclerosis and post-angioplasty restenosis.

223. Mutat Res 1998 Jun 18;402(1-2):299-306

Antimutagenic activity of tea towards 2-hydroxyamino-3-methylimidazo[4,5-f]quinoline: effect of tea concentration and brew time on electrophile scavenging.

Hernaez JF, Xu M, Dashwood RH

Department of Environmental Biochemistry, University of Hawaii, Honolulu, HI 96822, USA.

Green tea and black tea inhibit colon carcinogenesis in rats exposed to the cooked meat-derived mutagen 2-amino-3-methylimidazo[4, 5-f]quinoline (IQ). The present study compared the inhibitory activities of green tea and black tea towards a direct-acting mutagenic metabolite of IQ, namely 2-hydroxyamino-3-methylimidazo[4, 5-f]quinoline (N-hydroxy-IQ), under various brewing conditions. The following observations were made: (a) green tea (Sencha midoriiro) and black tea (English Breakfast tea) brewed at concentrations of 1. 25%, 2.5% or 5.0% (w/v) dose-relatedly inhibited the mutagenic activity of N-hydroxy-IQ in the Salmonella assay, (b) most of the antimutagenic components were released from the teas within 1-2 min of brewing, (c) under identical brewing conditions, green tea was significantly more effective than black tea, and (d) fractionation of green tea by HPLC revealed that most of the antimutagenic activity co-eluted with the compounds epigallocatechin (EGC) and epigallocatechin-3-gallate (EGCG), both of which are known for their anti-oxidant properties. These results suggest that catechins in tea might protect against such diverse reactive intermediates as free radicals and electrophiles formed during the metabolic activation of carcinogens and mutagens.

224. Mutat Res 1998 Jun 18;402(1-2):237-45

Inhibitory effects of antioxidants on formation of heterocyclic amines.

Oguri A, Suda M, Totsuka Y, Sugimura T, Wakabayashi K

Cancer Prevention Division, National Cancer Center Research Institute, 1-1 Tsukiji 5-chome, Chuo-ku, Tokyo 104, Japan.

It is important to search for effective antioxidants to suppress formation of mutagenic and carcinogenic heterocyclic amines (HCAs), like 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), because these HCAs are considered to be probable human carcinogens. The effects of various food-derived antioxidants on MeIQx formation were examined by their addition (0.2 mmol each) to mixtures of creatine (0.4 mmol), glycine (0.4 mmol) and glucose (0.2 mmol), and heating at 128 degreesC for 2 h. Glycine was replaced by l-phenylalanine in the case of PhIP formation. Among the 14 kinds of antioxidants tested, green tea catechins and the major component [(-)-epigallocatechin gallate], two flavonoids (luteolin and quercetin) and caffeic acid were found to clearly suppress the formation of both MeIQx and PhIP, being 3.2-75% of the level of the controls. These phenolic antioxidants also reduced the total mutagenicity of the heated mixtures. The results suggest that foodstuffs containing catechins, flavonoids and caffeic acid may suppress the formation of HCAs in cooked foods.

225. Carcinogenesis 1998 Apr;19(4):611-6

Inhibition of growth and induction of apoptosis in human cancer cell lines by tea polyphenols.

Yang GY, Liao J, Kim K, Yurkow EJ, Yang CS

Laboratory for Cancer Research, College of Pharmacy, Rutgers University, Piscataway, NJ 08855-0789, USA.

In order to study the biological activities of tea preparations and purified tea polyphenols, their growth inhibitory effects were investigated using four human cancer cell lines. Growth inhibition was measured by [3H]thymidine incorporation after 48 h of treatment. The green tea catechins (-)-epigallocatechin-3-gallate (EGCG) and (-)-epigallocatechin (EGC) displayed strong growth inhibitory effects against lung tumor cell lines H661 and H1299, with estimated IC50 values of 22 microM, but were less effective against lung cancer cell line H441 and colon cancer cell line HT-29 with IC50 values 2- to 3-fold higher. (-)-Epicatechin-3-gallate, had lower activities, and (-)-epicatechin was even less effective. Preparations of green tea polyphenols and theaflavins had higher activities than extracts of green tea and decaffeinated green tea. The results suggest that the growth inhibitory activity of tea extracts is caused by the activities of different tea polyphenols. Exposure of H661 cells to 30 microM EGCG, EGC or theaflavins for 24 h led to the induction of apoptosis as determined by an annexin V apoptosis assay, showing apoptosis indices of 23, 26 and 8%, respectively; with 100 microM of these compounds, the apoptosis indices were 82, 76 and 78%, respectively. Incubation of H661 cells with EGCG also induced a dose-dependent formation of H2O2. Addition of H2O2 to H661 cells caused apoptosis in a manner similar to that caused by EGCG. The EGCG-induced apoptosis in H661 cells was completely inhibited by exogenously added catalase (50 units/ml). These results suggest that tea polyphenol-induced production of H2O2 may mediate apoptosis and that this may contribute to the growth inhibitory activities of tea polyphenols in vitro.

226. Oncol Rep 1998 Mar-Apr;5(2):527-9

Induction of apoptosis in human stomach cancer cells by green tea catechins.

Hibasami H, Komiya T, Achiwa Y, Ohnishi K, Kojima T, Nakanishi K, Akashi K, Hara Y

Faculty of Medicine, Mie University, Tsu-city, Mie 514, Japan.

The exposure of human stomach cancer KATO III cells to green tea catechin extract and epigallocatechin gallate (EGCG), a main component of the extract led to both growth inhibition and the induction of programmed cell death (apoptosis). Morphological changes showing apoptotic body were observed in the cells treated with green tea catechin extract and EGCG. The fragmentation of DNA to oligonucleosomal-sized fragments, characteristic of apoptosis was determined to be concentration- and time-dependent. These data suggest that drinking of green tea in large amounts is recommended possibly to protect humans from stomach cancer.

227. Biosci Biotechnol Biochem 1998 Mar;62(3):532-4

Isolation and identification of acetyl-CoA carboxylase inhibitors from green tea (Camellia sinensis).

Watanabe J, Kawabata J, Niki R

Department of Bioscience and Chemistry, Faculty of Agriculture, Hokkaido University, Sapporo, Japan. junk@chem.agr.hokudai.ac.jp

An aqueous methanol extract from green tea showed potent acetyl-CoA carboxylase inhibitory activity. An active compound was isolated from the extract and identified as (-)-epigallocatechin gallate by instrumental analyses. The IC50 value of (-)-epigallocatechin gallate was 3.1 x 10(-4) M. Among tea catechins and related compounds, nearly equal activity was found in (-)-epigallocatechin gallate and (-)-epicatechin gallate, whereas (+)-catechin, (-)-epicatechin, (-)-epigallocatechin, gallic acid and methyl gallate each had no inhibitory activity. These results indicate that the 3-O-gallate group of the catechin structure was necessary for this activity. (-)-Epigallocatechin gallate inhibited triglyceride accumulation in 3T3-L1 cells at a concentration of 1.0 x 10(-7) M or higher.

228. Eur J Cancer Prev 1998 Feb;7(1):61-7

Prevention by antioxidants of heterocyclic amine-induced carcinogenesis in a rat medium-term liver bioassay: results of extended and combination treatment experiments.

Hirose M, Futakuchi M, Tanaka H, Orita SI, Ito T, Miki T, Shirai T

First Department of Pathology, Nagoya City University, Medical School, Japan.

The effects of 1-O-hexyl-2,3,5-trimethylhydroquinone (HTHQ) and other antioxidants on heterocyclic amine (HCA)-induced rat hepatocarcinogenesis were examined in a medium-term liver bioassay. In one study the experimental period was extended for up to 28 weeks to confirm the inhibition of 2-amino-6-methyldipyrido[1,2-a:3',2'-d]imidazole (Glu-P-1)-induction of glutathione-S-transferase placental form (GST-P) positive foci detected earlier in an 8-week experiment. Six-week-old male F344 rats were given a single i.p. injection of diethylnitrosamine (DEN) (200 mg/kg b.w.), and starting 2 weeks later, groups of 20 animals received a diet containing 0.03% Glu-P-1 together with 0.5% HTHQ, Glu-P-1 alone, HTHQ alone or a basal diet alone for 26 weeks. Three weeks after the DEN injection, animals were subjected to partial hepatectomy. The combined incidence of hepatocellular adenomas and carcinomas in the group fed Glu-P-1 alone was 89%, in contrast to 40% with simultaneous HTHQ treatment, and near the control level of 30% without Glu-P-1 and HTHQ. In the second experiment, to assess the effects of HTHQ on HCAs in combination, to mimic the human situation, after DEN initiation groups of 15 rats received diets containing a 0.0155% HCA mixture (0.003% Glu-P-1, 0.0015% 3-amino-1,4-dimethyl-5-H-pyrido[4,3-b]indole (Trp-P-1), 0.004% 2-amino-3-methyl-9H-pyrido[2,3-b]indole (MeAaC), 0.003% 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and 0.004% 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), which are all heptocarcinogens) together with 0.5 or 0.125% HTHQ, HCA alone, 0.5 or 0.125% HTHQ alone, or basal diet alone for 6 weeks. The numbers of GST-P positive foci decreased in a dose-dependent manner to 12.2+/-3.1 and 7.2+/-2.4 by the simultaneous treatment with 0.125 and 0.5% HTHQ, respectively, from a value of 17.6+/-3.6 for the HCA mix alone. In a third experiment, after DEN initiation, groups of 15 rats were placed on diets containing 0.02% MeIQx together with 0.25% HTHQ, 0.05% phenylethyl isothiocyanate (PEITC), 1% green tea catechins (GTC) or a mixture of HTHQ, PEITC and GTC, MeIQx alone, antioxidants alone or in combination, or basal diet alone for 6 weeks. These compounds were previously shown to inhibit HCA-associated GST-P positive foci. The numbers of GST-P positive foci in rats treated with MeIQx together with HTHQ (7.7+/-2.6) or antioxidant mixture (0.4+/-2.8) were significantly lower than with MeIQx alone (12.1+/-3.1), but a clear synergistic effect was not demonstrated. These results confirmed the ability of HTHQ to inhibit hepatocarcinogenesis induced by HCAs.

229. Mutat Res 1998 Jan 13;412(1):91-8

Inhibition of N-nitrosation of secondary amines in vitro by tea extracts and catechins.

Tanaka K, Hayatsu T, Negishi T, Hayatsu H

Meiji College of Pharmacy, Tokyo, Japan.

Inhibition of nitrite-mediated N-nitrosation of dimethylamine, morpholine and N-methylaniline by tea extracts and by 6 individual catechins in the extracts was studied. The inhibitions were detected by quantifying the nitrosamines formed. Eight different kinds of teas (5 green teas, a roasted green tea, an oolong tea, and a black tea) were examined for their inhibitory abilities and for their catechin contents, with an attempt to correlate the inhibitory activities to the catechin contents. The results showed that (1) the green tea extracts inhibit strongly the N-nitrosation of the three secondary amines tested, (2) the 6 catechins, notably epigallocatechin, are capable of blocking the N-nitrosations very efficiently, even more efficiently than ascorbic acid, and (3) the inhibition activities of green tea extracts are mostly ascribable to the catechins present in the extracts. These inhibitions occur by rapid reactions between nitrite and the catechins. It was observed that no mutagenicity results from the reaction between the tea extracts and nitrite.

230. Biochem Pharmacol 1997 Dec 15;54(12):1281-6

Inhibition of inducible nitric oxide synthase gene expression and enzyme activity by epigallocatechin gallate, a natural product from green tea.

Chan MM, Fong D, Ho CT, Huang HI

Department of Biomedical Sciences, Pennsylvania College of Podiatric Medicine, Philadelphia 19107-2496, USA. chan@biology.rutgers.edu

Chronic inflammation has been implicated as the underlying factor in the pathogenesis of many disorders. In the past decade, inflammation-related endogenous production of reactive nitrogen species, similar to oxygen free radicals, has also been suggested as a risk factor for cancer, in addition to the well-studied exogenous nitroso compounds. Epidemiological, in vitro, and animal model studies have implicated green tea to be protective against nitroso compound-induced and inflammation-related cancer. Therefore, we investigated the effect of epigallocatechin-3-gallate (EGCG), one of the known biologically active catechins contained in green tea, on the production of nitric oxide (NO.). We have shown previously that EGCG reduces NO. production as measured by nitrite accumulation in the culture medium. Expanding on this finding, in this report we show that EGCG may do so by two mechanisms: reduction of inducible nitric oxide synthase (iNOS) gene expression and inhibition of enzyme activity. Addition of 1-10 microM EGCG to lipopolysaccharide- and interferon-gamma-activated mouse peritoneal cells reduced iNOS mRNA expression concentration dependently, to 82-14%, as measured by relative reverse transcription-polymerase chain reaction. Addition of 50-750 microM EGCG, in a concentration-dependent manner, inhibited the enzyme activity of iNOS, to 85-14%, and neuronal nitric oxide synthase (nNOS), to 93-56%, as measured by citrulline formation. EGCG competitively inhibited binding of arginine and tetrahydrobiopterin, and the gallate structure is important for this action.

231. Biosci Biotechnol Biochem 1997 Dec;61(12):1981-5

Dose-dependent incorporation of tea catechins, (-)-epigallocatechin-3-gallate and (-)-epigallocatechin, into human plasma.

Nakagawa K, Okuda S, Miyazawa T

Food Chemistry Laboratory, Faculty of Agriculture, Tohoku University, Sendai, Japan.

Tea catechins, (-)-epigallocatechin-3-gallate (EGCg) and (-)-epigallocatechin (EGC), have been reported to suppress oxidation of plasma low density lipoprotein (LDL) in vitro. If dietary catechins can be efficiently incorporated into human blood plasma, anti-atherosclerotic effects in preventing oxidative modification of LDL would be expected. In this study, a newly developed chemiluminescence detection-high pressure liquid chromatography (CL-HPLC) method for measuring plasma catechins was used and the incorporation of EGCg and EGC into human plasma was investigated. Healthy subjects orally ingested 3, 5, or 7 capsules of green tea extract (corresponding to 225, 375, and 525 mg EGCg and 7.5, 12.5, and 17.5 mg EGC, respectively). The plasma EGCg and EGC concentrations before the administration were all below the detection limit (< 2 pmol/ml), but 90 min after, significantly and dose-dependently increased to 657, 4300, and 4410 pmol EGCg/ml, and 35, 144, and 255 pmol EGC/ml, in the subjects who received 3, 5, and 7 capsules, respectively. Both EGCg and EGC levels detected in plasma corresponded to 0.2-2.0% of the ingested amount. Catechin intake had no effect on the basal level of endogenous antioxidants (alpha-tocopherol, beta-carotene, and lycopene) or of lipids in plasma. These results suggested that drinking green tea daily would contribute to maintain plasma catechin levels sufficient to exert antioxidant activity against oxidative modification of lipoproteins in blood circulation systems.

232. Biochem Pharmacol 1997 Nov 1;54(9):973-8

Protective effects of tea polyphenols against oxidative damage to red blood cells.

Grinberg LN, Newmark H, Kitrossky N, Rahamim E, Chevion M, Rachmilewitz EA

Department of Hematology, Hadassah University Hospital-Hebrew University Medical School, Jerusalem, Israel.

Tea polyphenols (TPP) from black and green teas were evaluated for their antioxidant effects on normal red blood cells (RBC) and beta-thalassemic RBC membranes challenged with exogenous oxidants in vitro. The TPP of both types protected RBC against primaquine-induced lysis; they also protected the whole cells and the membranes against H2O2-induced lipid peroxidation so that about 80% protection was reached at [TPP] = 10 microg/mL. TPP from black tea at the same concentration protected normal RBC from morphological alterations caused by the peroxide treatment. The mechanism of the effects of TPP was investigated using a chemical system generating .OH (iron + ascorbic acid). TPP from both black and green teas inhibited the .OH fluxes in a concentration-dependent manner, indicating the possibility of iron chelation by TPP. Spectrophotometric titration revealed that TPP could stoichiometrically bind ferric iron to form a redox-inactive Fe-TPP complex. Quantitative analysis suggests that one or more major catechins from the TPP preparations are the likely iron-binding compounds accounting for the antioxidant effects of TPP on RBC.

233. Biosci Biotechnol Biochem 1997 Sep;61(9):1504-6

Inhibition of collagenases from mouse lung carcinoma cells by green tea catechins and black tea theaflavins.

Sazuka M, Imazawa H, Shoji Y, Mita T, Hara Y, Isemura M

School of Food and Nutritional Sciences, University of Shizuoka, Japan.

Theaflavin and theaflavin digallate, which are components of black tea were examined by in vitro invasion assay with mouse Lewis lung carcinoma LL2-Lu3 cells, which are highly metastatic. The compounds inhibited invasion by the tumor cells. Gelatin zymography showed that the cells secreted matrix metalloproteinases (MMPs), probably including MMP-2 and MMP-9, which may be involved in tumor cell invasion and metastasis. Theaflavin and theaflavin digallate also inhibited MMPs from the culture medium of these tumor cells, as did (-)-epigallocatechin gallate. These results suggest that theaflavin, theaflavin digallate, and (-)-epigallocatechin gallate inhibit tumor cell invasion by inhibiting type IV collagenases of the LL2-Lu3 cells.

234. Pancreas 1997 Aug;15(2):109-12

Effect of green tea catechins on the amount of 8-hydroxydeoxyguanosine (8-OHdG) in pancreatic and hepatic DNA after a single administration of N-nitrosobis(2-oxopropyl)amine (BOP).

Takabayashi F, Harada N, Tahara S, Kaneko T, Hara Y

Hamamatsu College, University of Shizuoka, Japan.

Effects of green tea catechins on N-nitrosobis(2-oxopropyl)amine (BOP)-induced oxidative stress in pancreas and liver were examined. Hamsters were divided into two groups: one group was given free access to a 0.1% solution of green tea catechins as drinking water (c-ham) and the other to plain tap water (w-ham) for 1 week before subcutaneous injection of BOP 20 mg/kg body weight. Zero, 1, 2, 6, 12, 24, and 48 h after BOP injection, the pancreas and liver were excised and the tissue concentration of lipid peroxides (TBA values) and the amount of 8-hydroxydeoxyguanosine (8-OHdG) in nuclear DNA were measured. The concentration of lipid peroxides and the amount of 8-OHdG in the pancreas showed similar patterns of change between c- and w-ham. Soon after BOP injection, the concentration of lipid peroxides and the amount of 8-OHdG increased with a peak at 1 and 6 h, respectively. Their peak values of c-ham were significantly depressed compared with those of w-ham. Both levels returned to steady-state levels by 24 h. In the liver, the concentration of lipid peroxides and the amount of 8-OHdG were not affected by BOP administration. These results suggest that BOP induces oxidative damages in the target organ and oral intake of green tea catechins has a protective effect on the oxidative stress.

235. Yakugaku Zasshi 1997 Jul;117(7):448-54

[Effect of tea extracts, catechin and caffeine against type-I allergic reaction].

[Article in Japanese]

Shiozaki T, Sugiyama K, Nakazato K, Takeo T

Institute of Traditional Chinese Medicines, School of Pharmaceutical Sciences, University of Shizuoka, Japan.

The antiallergic effects of green tea, oolong tea, and black tea extracts by hot water were examined. These extracts inhibited the passive cutaneous anaphylaxis (PCA) reaction of rat after oral administration. Three tea catechins, (--)-epigallocatechin (EGC), (--)-epicatechin gallate (ECg), and (--)-epigallocatechin gallate (EGCg) isolated from green tea showed stronger inhibitory effects than that of a green tea extract on the PCA reaction. The inhibitory effects of EGC and EGCg on the PCA reaction were greater than that of ECg. Caffeine also showed a inhibitory effect on the PCA reaction. These results indicate that tea could provide a significant protection against the type-I allergic reaction. These findings also suggest that tea catechins and caffeine play an important role in having an inhibitory effect on the type-I allergic reaction.

236. Cancer Lett 1997 Jun 3;116(1):47-52

Post-initiation inhibitory effects of green tea catechins on 7,12-dimethylbenz[a]anthracene-induced mammary gland carcinogenesis in female Sprague-Dawley rats.

Tanaka H, Hirose M, Kawabe M, Sano M, Takesada Y, Hagiwara A, Shirai T

First Department of Pathology, Nagoya City University Medical School, Mizuho-ku, Japan.

The dose-dependence of green tea catechin (GTC) effects on 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary gland carcinogenesis were investigated in female Sprague-Dawley rats. Groups of 20 6-week-old rats were treated with dietary 1, 0.1 or 0.01% GTC for 2 weeks and then basal diet alone for 35 weeks. At the end of week 1, they received a 25 mg/kg body weight intragastric dose of DMBA. Further groups of 20 7-week-old rats each were given an intragastric dose of 25 mg/kg body weight DMBA, and starting 1 week after DMBA treatment they were placed on diet containing 1, 0.1 or 0.01% GTC or basal diet alone for 35 weeks. Control rats were given 1% GTC or basal diet alone. The final incidences and multiplicities of mammary tumors were not significantly different between the groups treated with GTC at the same time as DMBA, compared to the DMBA alone control group. On the other hand, the final multiplicities of mammary tumors in groups treated with 1% GTC (P < 0.05) or 0.01% GTC (P < 0.01), but not 0.1% GTC, after DMBA treatment were significantly decreased as compared to the control value. These results indicate that whereas GTC may inhibit mammary carcinogenesis in the post-initiation stage, the effect is weak and not dose-dependent.

237. Environ Health Perspect 1997 Jun;105 Suppl 4:971-6

Polyphenols as inhibitors of carcinogenesis.

Yang CS, Lee MJ, Chen L, Yang GY

Laboratory for Cancer Research, Rutgers University, Piscataway, New Jersey 08855-0789, USA. csyang@rci.rutgers.edu

Many polyphenolic compounds have demonstrated anticarcinogenic activities in animal models. These compounds include flavanone, flavonols, isoflavone, and catechins. In this article, tea catechins will be used as an example to illustrate current research in this area. Many laboratory studies have demonstrated the inhibition of tumorigenesis in animal models by different tea preparations. The animal models include tumorigenesis in the mouse lung, rat and mouse esophagi, mouse forestomach, mouse skin, mouse duodenum, rat small intestine, rat and mouse livers, and rat colon. In most of the studies, the inhibitory activity of tea could be demonstrated when tea preparations were given either during or after the carcinogen treatment period. Black tea was also effective, although the activity was weaker than green tea in some experiments. Decaffeinated tea preparations were also active in many model systems. The molecular mechanisms for these broad inhibitory actions are not fully understood. They are most likely related to the biochemical actions of the tea polyphenols, which include antioxidative activities and inhibition of cell proliferation and of tumor promotion-related activities. The effect of tea consumption on human cancers is not clear in spite of numerous investigations. The bioavailability and pharmacokinetics of tea polyphenols are being studied in animals and humans to provide a basis for more quantitative analyses on the effect of tea on carcinogenesis. More mechanistic and dose-response studies will help us to understand the effects of tea consumption on human carcinogenesis.

238. Pancreas 1997 Apr;14(3):276-9

Effects of green tea catechins (Polyphenon 100) on cerulein-induced acute pancreatitis in rats.

Takabayashi F, Harada N

Hamamatsu College, University of Shizuoka, Japan.

Effects of green tea catechins (GTC) on cerulein-induced acute pancreatitis in rats were examined. The acute pancreatitis induced by cerulein (cerulein pancreatitis) was characterized by interstitial edema and vacuolation. When cerulein pancreatitis was induced, prior administration of 0.1% GTC in drinking water for 1 week before the induction significantly decreased the wet weight of the pancreas, the serum level of amylase, and the tissue concentration of lipid peroxides in the pancreas compared with those in nonmedicated rats supplied with plain tap water only. Furthermore, the pancreatic tissue alterations of the medicated rats were milder than those of the nonmedicated rats. These data suggest that GTC have a protective effect on the pathogenesis of cerulein pancreatitis.

239. Cancer Lett 1997 Mar 19;114(1-2):153-8

Screening of anticarcinogenic ingredients in tea polyphenols.

Han C

Institute of Nutrition and Food Hygiene, Chinese Academy of Preventive Medicine, Beijing.

A batch of short-term tests were used to test the antimutagenic activities of Chinese green tea water extract (TWE), tea polyphenols (TP), and tea catechins (EGCG, ECG, EGC, EC). In the V79 cell forward gene mutation and V79 cell cytokinesis-block micronuclei tests, all samples showed significant inhibitory effects on mitomycin, which indicates their effects on the initiation stage of chemical carcinogenesis. However, none of the catechins and TP had effects as strong as the TWE on the basis of their relative contents in tea. Of the four catechins, ECG and EGCG were the most potent. Using the V79 cell metabolic co-operation test as an indicator for the promotion stage, TWE and TP showed weak inhibitory effects and the individual catechins showed much stronger inhibition. The test samples also showed non-specific inhibitory effects on HeLa cell growth in soft agar, which was designed to test their effects on the progression stage.

240. Anticancer Drugs 1997 Mar;8(3):265-8

Green tea catechins (EGCG and EGC) have modulating effects on the activity of doxorubicin in drug-resistant cell lines.

Stammler G, Volm M

Deutsches Krebsforschungszentrum, Department 0511, Heidelberg, Germany.

The chemopreventive effect of polyphenols from green tea [e.g. (-)-epigallocatechin gallate (EGCG) and (-)-epigallocatechin (EGC)] against cancer has been demonstrated in several studies. The aim of this investigation was to prove whether these compounds modulate the activity of antineoplastic drugs. Therefore, the influence of EGCG and EGC was tested on doxorubicin-resistant murine sarcoma (S180-dox) and human colon carcinoma (SW620-dox) cell lines. Both substances showed a sensitizing effect on the cell lines if they had been treated with doxorubicin. These results suggest that protein kinase C may be inhibited by EGCG and EGC, and this may lead to a reduced expression of some drug resistance related proteins.

241. Med Hypotheses. 1997 Mar;48(3):215-20.

natural antimutagenic agents may prolong efficacy of human immunodeficiency virus drug therapy.

McCarty MF.

Nutrition 21, San Diego, CA 92109, USA.

The long-term efficacy of new combination drug therapies for human immunodeficiency virus infection may be limited by the tendency of transfected human immunodeficiency virus to mutate to drug-resistant forms. This argues for the use of safe antimutagenic measures as adjuvants to such therapies. Certain nutrients and food factors-notably selenium, green-tea polyphenols, and cruciferous phytochemicals-can suppress cancer initiation and mutagenesis in animal and cell culture models; epidemiological studies suggest that ambient variations in consumption of these food factors can have an important impact on human cancer rates. Low-fat diets may reduce deoxyribonucleic acid base damage in human leukocytes, whereas increased body iron stores are likely to increase mutation rates. Thus, ample but safe intakes of selenium, green-tea polyphenols, and cruciferous vegetables, in the context of a diet low in fat and assimilable iron, can be expected to prolong the efficacy of drug therapy in subjects infected with the human immunodeficiency virus. These measures can also be recommended for cancer prevention in the general population.

242. Cancer Lett 1997 Jan 30;112(2):141-7

Effects of green tea catechins on the progression or late promotion stage of mammary gland carcinogenesis in female Sprague-Dawley rats pretreated with 7,12-dimethylbenz(a)anthracene.

Hirose M, Mizoguchi Y, Yaono M, Tanaka H, Yamaguchi T, Shirai T

First Department of Pathology, Nagoya City University, Medical School, Japan.

Effects of the green tea catechins (GTCs) on the late promotion or progression stage of mammary gland carcinogenesis were examined in female Sprague-Dawley (SD) rats pretreated with 7,12-dimethylbenz(a)anthracene (DMBA). A total of 84 7-week-old rats received a 50 mg/kg body weight intra-gastric dose of DMBA, and starting 13 weeks thereafter, when the tumor incidence had reached 50%, three groups of 28 animals each were placed on diet containing 0.5% Polyphenon E (58.4% content (-)-epigallocatechin gallate (EGCG)) (groups 1a and 1b), 0.5% EGCG-80 (81% content of EGCG) (groups 2a and 2b) or basal diet alone (groups 3a and 3b) for 23 weeks. The experiment was terminated at week 36. The growth (i.e. change in mean diameter) of mammary tumors present at week 13 (groups 1a, 2a and 3a) was not influenced by the treatment with EGCGs, with no significant intergroup differences in the lesion incidences, multiplicity or size being observed. Values for these parameters did show a tendency for decrease in group 2b (Polyphenon E) as compared to group 3b (control) during the study, but they were not significantly reduced at the sacrifice time point. These results indicate that GTCs are not effective at inhibiting progression of rat mammary carcinogenesis, but Polyphenon E may exert a weak inhibitory effect on the early promotion stage.

243. FEBS Lett 1997 Jan 20;401(2-3):230-4

Green tea catechins such as (-)-epicatechin and (-)-epigallocatechin accelerate Cu2+-induced low density lipoprotein oxidation in propagation phase.

Yamanaka N, Oda O, Nagao S

The Bio-Dynamics Research Institute, Nagoya Memorial Hospital, Tenpaku-ku, Japan.

Effects of (-)-epicatechin (EC) and (-)-epigallocatechin (EGC) on Cu2+-induced low density lipoprotein (LDL) oxidation were studied in initiation and propagation phases. When 1.5 microM EC or EGC was added to the mixture of isolated human LDL and Cu2+ in the initiation phase, the oxidation of LDL was inhibited in agreement with previous findings. In contrast, in the propagation phase, 1.5 microM of EC or EGC worked as an accelerator of the oxidation, and acceleration ratios (maximum about 6 times) were modified depending on the concentrations of catechin used and the oxidation process in the propagation phase. The evidence was obtained from formation of thiobarbituric acid reactive substances (TBARS), detecting conjugated diene measured by absorbance at 234 nm and investigating fragmentation of apoprotein B (apo B) in LDL. Even in the propagation phase of LDL oxidation, the elevated concentrations of EC or EGC worked as inhibitors: after 40 min incubation of LDL with Cu2+, 10.0 microM EC or 2.0 microM EGC inhibited LDL oxidation. Yet, nitric oxide (NO) released from 5 microM zwitterionic polyamine/NO adducts had an inhibitory in all phases of LDL oxidation. These results indicate that catechins such as EC and EGC can act as free radical terminators (reducing agents) or accelerators (oxidizing agents) under oxidation circumstances, which is a different character from NO. From the above evidence, further investigations are needed on many natural flavonoids, the most potent antioxidative compounds in foods.

244. J Cell Biochem Suppl 1997;27:52-8

Influence of tea catechins on the digestive tract.

Hara Y

Food Research Institute, Mitsui Norin Co., Ltd., Shizuoka Pref., Japan.

Tea catechins undergo various metabolic changes after they are taken orally, though a large percentage are excreted intact with the feces. Epidemiological studies suggest a protective effect of tea against various human cancers, including colon and rectum. The bactericidal property of tea catechins plays several roles in the digestive tract. In the small intestine, catechins inhibit alpha-amylase activity, and a certain amount is absorbed into the portal vein. Although catechins are bactericidal, they do not affect lactic acid bacteria. Including tea catechins in the diet for several weeks decreases putrefactive products and increases organic acids by lowering pH. These changes were achieved in tube-fed patients by administering 100 mg of tea catechins (equivalent to a cup of green tea) three times daily with meals for 3 weeks. When catechin administration ceased, the effects reversed after 1 week. catechins should be considered further in colon carcinogenesis studies.

245. Mutat Res 1996 Dec 12;361(2-3):179-86

Bio-antimutagenic activity of green tea catechins in cultured Chinese hamster V79 cells.

Kuroda Y

Department of Environmental Health Science, Azabu University, Kanagawa, Japan.

The antimutagenic effects of green tea catechins, (-)-epicatechin gallate (ECg) and (-)-epigallocatechin gallate (EGCg) on induction of 6-thioguanine (6TG)-resistant mutations induced by 4-nitroquinolin 1-oxide (4NQO) were found in cultured Chinese hamster V79 cells. The antimutagenic activity of catechins was found only when cells were post-treated with catechins during the mutation expression time after treatment with 4NQO, and not found by simultaneous treatments with 4NQO and catechins. This bioantimutagenic activity of catechins were not observed in ethyl methanesulfonate (EMS)-induced mutations. This suggests that the antimutagenic effects of catechins may act intracellularly as bio-antimutagenic blocking agent or suppressive agent. These catechins had no effects on the cytotoxic activity of 4NQO in V79 cells, whether catechins were used in simultaneous treatment with or in post-treatment after 4NQO. This indicates that the antimutagenicity and anticytotoxicity to 4NQO may be caused by different mechanism(s).

246. Nutr Cancer. 1996;26(3):325-35.

Prevention of photocarcinogenesis by topical administration of pure epigallocatechin gallate isolated from green tea.

Gensler HL, Timmermann BN, Valcic S, Wachter GA, Dorr R, Dvorakova K, Alberts DS.

Arizona Cancer Center, Department of Radiation Oncology, USA.

Topical application of purified (-)-epigallocatechin-3-gallate (EGCG), a polyphenolic antioxidant isolated from green tea, inhibited photocarcinogenesis in BALB/cAnNHsd mice with no visible toxicity. Mice were treated with 0, 10, or 50 mg of EGCG in 200 microliters of acetone three times weekly for three weeks before ultraviolet (UV) treatments began and throughout the experiment. UV radiation consisted of five 30-minute exposures per week to banks of six FS40 Westinghouse sunlamps for 25 weeks. In the photocarcinogenesis study, mice received a total dose of approximately 2.1 x 10(6) J/m2. Skin cancer incidence in UV-irradiated mice was 96% at 28 weeks after the first UV treatment; EGCG at 10 or 50 mg reduced this incidence to 62% and 29%, respectively. UV-induced immunosuppression, assessed by the inability of UVB-irradiated mice to reject a syngeneic antigenic tumor, was not influenced by topical EGCG. Oral administration of 0, 100, or 500 mg of pure EGCG per liter of drinking water (approximately 0, 0.56, or 2.8 mg/day, respectively) did not decrease UV-induced skin tumor incidence, rate of primary tumor growth, or inability to reject antigenic tumors. Thus induction of skin tumors by UV radiation was significantly reduced by topical, but not by oral, administration of purified EGCG through a mechanism distinct from inhibition of photoimmunosuppression.

247. FEMS Microbiol Lett 1996 Sep 15;143(1):35-40

Peroxidase-catalyzed generation of catechin oligomers that inhibit glucosyltransferase from Streptococcus sobrinus.

Hamada S, Kontani M, Hosono H, Ono H, Tanaka T, Ooshima T, Mitsunaga T, Abe I

Department of Oral Microbiology, Osaka University Faculty of Dentistry, Suita-Osaka, Japan.

Oolong tea extract (OTE) and the purified polymeric polyphenols from OTE have been found to inhibit glucosyltransferase (GTase) of mutans streptococci. In view of the partial fermentation characteristic of oolong tea, we describe here an in vitro model reaction system to produce partially fermented products of D-(+)-catechin or green tea extract (GTE) using horseradish peroxidase. A dimeric catechin molecule was identified as dehydro-dicatechin A by instrumental analyses. The molecular size of some oligomeric catechins was estimated by the elution profile with HPLC. These catechin oligomers markedly inhibited GTase from Streptococcus sobrinus 6715. As the degree of polymerization of catechin or GTE increased, GTase was inhibited more effectively. These results suggest that polymeric polyphenols found in OTE are synthesized by partial fermentation due to oxidases/peroxidases present in tea leaves.

248. Anticancer Drugs. 1996 Jun;7(4):461-8.

Inhibitory effect of six green tea catechins and caffeine on the growth of four selected human tumor cell lines.

Valcic S, Timmermann BN, Alberts DS, Wachter GA, Krutzsch M, Wymer J, Guillen JM.

Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson 85721, USA.

Green tea is an aqueous infusion of dried unfermented leaves of Camellia sinensis (family Theaceae) from which numerous biological activities have been reported including antimutagenic, antibacterial, hypocholesterolemic, antioxidant, antitumor and cancer preventive activities. From the aqueous-alcoholic extract of green tea leaves, six compounds (+)-gallocatechin (GC), (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), (-)-epigallocatechin gallate (EGCG) and caffeine, were isolated and purified. Together with (+)-catechin, these compounds were tested against each of four human tumor cells lines (MCF-7 breast carcinoma, HT-29 colon carcinoma, A-427 lung carcinoma and UACC-375 melanoma). The three most potent green tea components against all four tumor cell lines were EGCG, GC and EGC. EGCG was the most potent of the seven green tea components against three out of the four cell lines (i.e. MCF-7 breast cancer, HT-29 colon cancer and UACC-375 melanoma). On the basis of these extensive in vitro studies, it would be of considerable interest to evaluate all three of these components in comparative preclinical in vivo animal tumor model systems before final decisions are made concerning which of these potential chemopreventive drugs should be taken into broad clinical trials.

249. Biosci Biotechnol Biochem 1996 Jun;60(6):1000-5

Effectiveness of green tea tannin on rats with chronic renal failure.

Yokozawa T, Chung HY, He LQ, Oura H. Research Institute for Wakan-Yaku, Toyama Medical and Pharmaceutical University, Japan.

The effects of green tea tannin on nephrectomized rats were examined. There were increases in blood urea nitrogen, serum creatinine, and urinary protein, and a decrease in creatinine clearance in the nephrectomized control rats, whereas better results for these parameters were obtained in rats given green tea tannin after nephrectomy, demonstrating a suppressed progression of the renal failure. When the renal parenchyma was partially resected, the remnant kidney showed a decrease in the activity of radical scavenger enzymes. Green tea tannin, however, was found to lighten the kidney under such oxidative stress. Mesangial proliferation and glomerular sclerotic lesions, which were conspicuous in the rats that were not given green tea tannin after nephrectomy, were also relieved.

250. Cancer. 1996 Apr 15;77(8 Suppl):1662-7.

Inhibitory effects and toxicity of green tea polyphenols for gastrointestinal carcinogenesis.

Yamane T, Nakatani H, Kikuoka N, Matsumoto H, Iwata Y, Kitao Y, Oya K, Takahashi T.

First Department of Surgery, Kyoto Prefectural University of Medicine, Japan.

BACKGROUND. Recently, and epidemiologic study showed a lower risk of gastrointestinal carcinogenesis in green tea drinkers. An experiment on two-stage skin carcinogenesis in mice showed that (-)-epigallocatechin gallate (EGCG), one of the main constituents of green tea, inhibited tumor formation. METHODS. The inhibitory effects of EGCG and green tea extract (GTE) on N-ethyl-N'-nitro-N-nitroguanidine (ENNG)-induced duodenal carcinogenesis in the mouse, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced carcinogenesis of the glandular stomach in the rat, and azoxymethane-induced colon carcinogenesis in the rat were examined. The toxicity of GTE was assessed experimentally and GTE was applied clinically in normal volunteers to determine the effective dose and to assess its harmful effects. RESULTS. EGCG and GRE inhibited chemical carcinogenesis of the gastrointestinal tract in rodents. Judging from the epidemiologic and experimental findings, it was determined that 1 g per day of GTE might be an effective dose. GTE was not toxic and no harmful effect was found during its clinical use. CONCLUSIONS. These findings suggest that EGCG and GTE are useful in preventing gastrointestinal carcinogenesis, and the clinical usefulness of GTE, which has no harmful effects and is inexpensive, should be studied further.

251. ree Radic Res. 1996 Mar;24(3):225-10.

Oxidation of caffeine and related methylxanthines in ascorbate and polyphenol-driven Fenton-type oxidations.

Stadler RH, Richoz J, Turesky RJ, Welti DH, Fay LB.

Nestec Ltd., Nestle Research Centre, Lausanne, Switzerland.

Caffeine and related methylxanthines were subjected to free radical mediated oxidation by incubation with Fe(3+)-EDTA/ascorbate and Fe(3+)-EDTA/polyphenolics. The reaction mixtures were analysed by reverse-phase HPLC, revealing the corresponding C-8 hydroxylated analogues as the major products of hydroxyl radical mediated attack. Further oxidation products of caffeine, analysed by liquid chromatography-mass spectrometry (LC-MS), were the N1-, N3- and N7-demethylated methylxanthine analogues theobromine, paraxanthine and theophylline, respectively. Isolable amounts of the imidazole ring operated 6-amino-5-(N-formylmethyl-amino)-1,3-dimethyl-uracil (1,3,7-DAU) derivative were also detected, which was characterised by 1H NMR and mass spectroscopy. The identified products indicate that the pertinent chemical reactions, i.e. C-8 hydroxylation, demethylations, and C8-N9 bond scission, are comparable to the primary metabolic pathways of caffeine in humans. The influence of pH, transition metals, hydrogen peroxide, free radical scavengers and metal chelators on caffeine oxidation was studied. This report illustrates that natural food-borne reactants can aid in identifying specific chemical markers of free radical induced damage. Furthermore, potentially anti-and pro-oxidative reactions can be elucidated which may be important in assessing the impact of nutrient additives and supplements on the shelf life and stability of foods and beverages.

252. Mutagenesis 1996 Mar;11(2):189-94

Antimutagenicity and catechin content of soluble instant teas.

Constable A, Varga N, Richoz J, Stadler RH

Nestec Ltd Research Centre, Vers-Chez-les-Blanc, Lausanne, Switzerland.

The antimutagenic properties of soluble instant teas were examined using the bacterial Ames assay. Inhibition of the numbers of revertants induced from a number of known mutagens indicates that aqueous extracts of instant teas have antimutagenic activity and antioxidative properties, and can inhibit nitrosation reactions. Despite a significant reduction in the amounts of major green tea catechins, quantified using reversed-phase HPLC with electro-chemical detection, no differences in antimutagenicity were observed between the instant teas, a black fermented tea and a green tea. Oxidation of polyphenolic compounds which occurs during the production of instant tea does not therefore decrease the antioxidant, free radical scavenging and antimutagenic properties. This suggests that catechins are not the only compounds responsible for the protective effects of teas.

253. Fundam Appl Toxicol. 1996 Feb;29(2):244-50.

Chemopreventive effects of green and black tea on pulmonary and hepatic carcinogenesis.

Cao J, Xu Y, Chen J, Klaunig JE.

Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis 46202-5196, USA.

The chemopreventive effects of decaffeinated green and black tea treatment on liver and lung tumorigenesis were examined in carcinogen-treated mice. Male C3H mice were given decaffeinated green or decaffeinated black tea in their drinking water prior to, during, and after treatment with diethylnitrosamine (50 micrograms/kg bw, i.p., once per week for 8 weeks). After 40 weeks of tea treatment, mice were sampled and examined for pulmonary and hepatic tumors. Mice treated with both DENA and tea displayed a significant decrease in the mean number of lung and liver tumors compared to DENA-only treated animals. Mice that received 0.63 or 1.25% green tea or 1.25% black tea exhibited a reduction in liver tumor numbers of 54, 50, and 63%, respectively from that seen in the DENA-only treated mice. Tea treatment also significantly decreased the multiplicity of lung adenomas. Mice receiving DENA and either 0.63 or 1.25% green tea or 1.25% black tea showed a decrease in the mean number of lung tumors of 40, 46, and 34%, respectively, from DENA-only treated mice. While a possible association between the chemopreventive activity of tea on lung tumor response and the concentration of (-) epigallocatechin gallate (EGCG) in the tea was suggested, no apparent relationship between EGCG concentration and liver tumor response was seen, however. These results show a dose-dependent chemoprevention of both lung and liver tumors by both black and green tea in diethylnitrosamine-treated C3H mice.

254. Natl Cancer Inst 1996 Jan 17;88(2):93-100

Consumption of black tea and cancer risk: a prospective cohort study.

Goldbohm RA, Hertog MG, Brants HA, van Poppel G, van den Brandt PA

Department of Epidemiology, Netherlands Organization for Applied Scientific Research [TNO] Nutrition and Food Research Institute, Zeist, The Netherlands.

BACKGROUND: Tea is one of the most frequently consumed beverages in the world. Antioxidant polyphenol compounds (such as catechins and flavonols) are abundantly present in both green and black teas and have been observed to have anticarcinogenic properties in cell and animal model studies. In black tea, however, most of the catechins have been oxidized to forms that may have reduced anticarcinogenic properties. Despite indications from experimental studies that tea may protect against cancer, epidemiologic evidence has been inconclusive. PURPOSE: The association between black tea consumption and the subsequent risk of stomach, colorectal, lung, and breast cancers was investigated in The Netherlands Cohort Study on Diet and Cancer among 58,279 men and 62,573 women aged 55-69 years. METHODS: Subjects in the cohort completed a self-administered questionnaire on dietary habits and other risk factors for cancer at base line in 1986. Follow-up for cancer was done by means of computerized record linkage with all nine regional cancer registries in The Netherlands and the national pathology database. During 4.3 years of follow-up, 200, 650, 764, and 650 cases of stomach, colorectal, lung, and breast cancers were diagnosed, respectively. The questionnaire data of case subjects and those of a random subcohort (n = 3500) were used to calculate rate ratios (RRs) of cancer in categories of consumers of black tea compared with nonconsumers. RESULTS: Tea was not used by 13% of the subjects in the cohort, whereas 37%, 34%, and 16% consumed one to two, three to four, and five or more cups of tea per day, respectively. No association was observed between tea consumption and risk of colorectal cancer: The risk among tea drinkers in each consumption category was similar to that among nondrinkers. The RR of breast cancer among consumers of five or more cups of tea per day was 1.3 (95% confidence interval = 0.9-2.0); no dose-response association was observed. In age- and sex-adjusted analyses, consumption of tea was inversely associated with stomach (two-sided P for trend = .147) and lung (two-sided P for trend < .001) cancers. However, tea drinkers appeared to smoke less and to eat more vegetables and fruits than nondrinkers. When smoking and dietary factors were taken into account, tea in itself did not appear to protect against stomach and lung cancers: The RRs in all consumption categories were close to unity. Analysis of the tea and cancer relationship in a subgroup that included subjects in the lowest two quintiles of consumption of vegetables and fruits also failed to reveal a protective effect of tea consumption on the risk of three cancer types studied (colorectal, lung, and breast cancers). CONCLUSIONS: This investigation does not support the hypothesis that consumption of black tea protects against four of the major cancers in humans; a cancer-enhancing effect was not evident, either.

255. Mutagenesis 1996 Jan;11(1):37-41

Relationship between antimutagenic activity and major components of various teas.

Yen GC, Chen HY

Department of Food Science, National Chung Hsing University, Taichung, Taiwan, Republic of China.

The objectives of this study were to determine the major components in tea leaves and tea extracts and to study the relationship between chemical content and antimutagenic activity of various tea extracts. The amount of catechins in various tea extracts was in the order: green tea (26.7%) > oolong tea (23.2%) > pouchong tea (15.8%) > black tea (4.3%). The amounts of caffeine and phenolic compounds in oolong tea extracts were 8.3 and 32.4%, respectively; these amounts were greater than those in the other three tea extracts. The ascorbic acid in green tea extracts was a little higher than in oolong and pouchong tea extracts. The amount of catechins in tea leaves also showed the order: nonfermented (green tea) > semifermented (pouchong tea and oolong tea) > fermented tea (black tea). The amounts of caffeine and phenolic compounds in oolong tea leaves are also higher than in other tea leaves. Besides water soluble components, tea leaves also contain several lipid soluble chemicals such as beta-carotene and tocopherols. The tea extracts, especially oolong and pouchong teas, markedly inhibited the mutagenicity of 2-amino-3-methylimidazo (4,5-f)quinoline (IQ), 3-amino-1,4-dimethyl-5H-pyrido-(4,3-b)indole (Trp-P-1), 2-amino-6-methyl-dipyrido(1,2-a:3',2'-d) imidazole (Glu-P-1), benzo[a]pyrene (B[a]P) and aflatoxin B1 (AFB1). The inhibitory effect of tea extracts against the mutagenicity of IQ and Glu-P-1 in Salmonella typhimurium TA100 showed a significant (P < 0.05) correlation to the contents of catechins and ascorbic acid. The antimutagenic activity of tea extracts to Trp-P-1 in TA98 or TA100 was well correlated (P < 0.05) to the caffeine contents. No significant (P > 0.05) correlation was found between the antimutagenicity of tea extracts to B[a]P and AFB1 in TA100 and the content of major components in tea extracts.

256. Cancer Causes Control. 1996 Jan;7(1):33-40.

Nutrition and esophageal cancer.

Cheng KK, Day NE.

Department of Public Health and Epidemiology, University of Birmingham, United Kingdom.

Epidemiologic evidence on the relation between nutrition and esophageal cancer is reviewed. Results from ecologic, case-control, cohort, and intervention studies are included. Most of the findings pertain more to squamous cell carcinoma than adenocarcinoma of the esophagus. The protective effect of fruit and vegetable consumption is supported by a large body of evidence, especially from case-control studies. The effects of food groups and nutrients other than fruits and vegetables also have been examined, but the overall evidence is less convincing. Recent intervention studies in high incidence areas in China indicate that micronutrient supplements may have a modest effect in reducing risk, but the generalizability of this result is uncertain. Hot drinks are likely to increase the risk of esophageal cancer. On the other hand, the role of tea drinking, especially the use of green tea, remains to be defined better.

257. Biosci Biotechnol Biochem 1996 Jan;60(1):169-70

Effects of green tea and tea catechins on the development of mammary gland.

Sayama K, Ozeki K, Taguchi M, Oguni I

Department of Animal Science, Shizuoka University, Japan.

To find whether green tea and tea catechins have effects on the development of mammary glands, virgin DDD mice were fed on diets containing green tea and tea catechins. The degree of mammary gland development was examined by duct-alveolar growth and DNA content. The results indicated that green tea, but not tea catechins, has a growth-promoting effect on mammary gland development.

258. Carcinogenesis 1995 Dec;16(12):3049-55

Inhibitory effects of 1-O-hexyl-2,3,5-trimethylhydroquinone (HTHQ), green tea catechins and other antioxidants on 2-amino-6-methyldipyrido[1,2-a:3',2'-d]imidazole (Glu-P-1)-induced rat hepatocarcinogenesis and dose-dependent inhibition by HTHQ of lesion induction by Glu-P-1 or 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx).

Hirose M, Hasegawa R, Kimura J, Akagi K, Yoshida Y, Tanaka H, Miki T, Satoh T, Wakabayashi K, Ito N, et al

First Department of Pathology, Nagoya City University, Medical School, Japan.

The effects of 1-O-hexyl-2,3,5-trimethylhydroquinone (HTHQ), green tea catechins (GTC), alpha-tocopherol, beta-carotene, chlorophyllin, phenylethylisothiocyanate (PEITC), 3-O-ethylascorbic acid (EAsA), 3-O-dodecylcarbomethyl ascorbic acid (DAsA), n-tritriacontane-16,18-dione (TTAD) and d-limonene on 2-amino-6-methyldipyrido[1,2-a:3',2'-d]imidazole (Glu-P-1)- or dimethylnitrosamine (DMN)-induced hepatocarcinogenesis, and the dose dependence of HTHQ inhibition of Glu-P-1- or 2-amino-3,8-dimethylimidazo [4,5-f]quinoxaline (MeIQx)-influence on lesion development were examined in a rat medium-term liver bioassay system featuring diethylnitrosamine initiation and partial hepatectomy. At the end of week 8, the number and total area of glutathione S-transferase placental form (GST-P) positive liver foci in rats treated with 0.03% Glu-P-1 alone were increased significantly (46.8 +/- 11.0 and 12.0 +/- 5.6 respectively) as compared to the control values (3.8 +/- 1.6 and 0.4 +/- 0.2). Combined treatment with 1% HTHQ remarkably reduced both of these parameters (8.1 +/- 2.1 and 0.6 +/- 0.2). GTC (1%), PEITC (0.1%), beta-carotene (0.1%) and DAsA (1%) also demonstrated inhibition but less than HTHQ. On the other hand, these antioxidants did not influence development of foci initiated by 0.002% DMN. In the dose-response study, up to 0.125% HTHQ significantly reduced the effects of 0.02% Glu-P-1 or 0.03% MeIQx on the number and area of foci. These results indicate that several antioxidants exert chemopreventive effects against heterocyclic amine (HCA)-induced hepatocarcinogenesis, and particularly HTHQ which thus deserves further attention as a chemopreventor in the contest of the environmentally important HCA group of carcinogens.

259. Cancer Lett 1995 Nov 27;98(1):27-31

Inhibitory effects of green tea infusion on in vitro invasion and in vivo metastasis of mouse lung carcinoma cells.

Sazuka M, Murakami S, Isemura M, Satoh K, Nukiwa T

School of Food and Nutritional Sciences, University of Shizuoka, Japan.

The peroral administration of green tea infusion reduced the number of lung colonies of mouse Lewis lung carcinoma cells in a spontaneous metastasis system. The experiments with artificially reconstituted basement membrane suggested that this reduction could be understood by the inhibitory effects of the green tea infusion and its constituent catechins on the penetration of the cells through the basement membrane.

260. Cancer Lett 1995 Sep 25;96(2):239-43

Growth inhibition and regression of human prostate and breast tumors in athymic mice by tea epigallocatechin gallate.

Liao S, Umekita Y, Guo J, Kokontis JM, Hiipakka RA

Ben May Institute, Department of Biochemistry and Molecular Biology, University of Chicago, IL 60637, USA.

The human prostate cancer cell lines, PC-3 (androgen-insensitive) and LNCaP 104-R (androgen-repressed) were inoculated subcutaneously into nude mice to produce prostate tumors. Intraperitoneal injection of green tea (-)epigallocatechin-3-gallate but not structurally related catechins, such as (-)epicatechin-3-gallate, inhibited the growth and rapidly reduced the size of human prostate tumors in nude mice. (-)Epigallocatechin-3-gallate also rapidly inhibited the growth of tumor growth formed by the human mammary cancer cell line MCF-7 in nude mice. It is possible that there is a relationship between the high consumption of green tea and the low incidence of prostate and breast cancers in some Asian countries.

261. Biochem Biophys Res Commun 1995 Sep 25;214(3):833-8

Selective inhibition of steroid 5 alpha-reductase isozymes by tea epicatechin-3-gallate and epigallocatechin-3-gallate.

Liao S, Hiipakka RA

Ben May Institute, University of Chicago, IL 60637, USA.

Inhibitors of 5 alpha-reductase may be effective in the treatment of 5 alpha-dihydrotestosterone-dependent abnormalities, such as benign prostate hyperplasia, prostate cancer and certain skin diseases. The green tea catechins, (-)epigallocatechin-3-gallate and (-)epicatechin-3-gallate, but not (-)epicatechin and (-)epigallocatechin, are potent inhibitors of type 1 but not type 2 5 alpha-reductase. (-)Epigallocatechin-3-gallate also inhibits accessory sex gland growth in the rat. These results suggest that certain tea gallates can regulate androgen action in target organs.

262. Pancreas 1995 Aug;11(2):127-31

The effects of green tea catechins (Polyphenon) on DL-ethionine-induced acute pancreatitis.

Takabayashi F, Harada N, Hara Y

Hamamatsu College, University of Shizuoka, Japan.

The effects of green tea catechins (Polyphenon) on DL-ethionine-induced acute pancreatitis in rats were examined. The acute pancreatitis induced in this study was characterized by moderate inter- and intrastitial edema and patchy acinar cell necrosis. In rats induced with acute pancreatitis by an intraperitoneal injection of DL-ethionine, the wet weight of the pancreas (0.47 +/- 0.059 g/100 g body weight; p < 0.05), the serum amylase (10,432 +/- 996 IU/L; p < 0.001), and the tissue concentration of lipid peroxides (19.5 +/- 1.78 nmol/mg tissue DNA; p < 0.001) were significantly increased compared with values obtained in control rats (0.39 +/- 0.037 g/100 g body weight, 5,639 +/- 1,568 IU/L, and 10.7 +/- 1.04 nmol/mg tissue DNA, respectively) injected with isotonic saline. In contrast, in rats injected with DL-ethionine and supplied with a green tea catechin solution as a beverage instead of water during the experimental period, the tissue of pancreas was almost-correct, and the wet weight of the pancreas (0.39 +/- 0.054 g/100 g body weight; p < 0.05), the serum amylase (5,716 +/- 708 IU/L; p < 0.001), and the concentration of lipid peroxides in tissue (11.5 +/- 2.15 nmol/mg tissue DNA; p < 0.001) were significantly decreased compared with values obtained in rats injected with DL-ethionine and supplied with water as a beverage. These data suggest that green tea catechins may have a protective effect on the pathogenesis of experimental acute pancreatitis.

263. Arch Biochem Biophys 1995 Oct 1;322(2):339-46

Polyphenolic flavanols as scavengers of aqueous phase radicals and as chain-breaking antioxidants.

Salah N, Miller NJ, Paganga G, Tijburg L, Bolwell GP, Rice-Evans C

Radical Research Group, UMDS--Guy's Hospital, University of London, United Kingdom.

The purpose of this investigation was to establish the relative antioxidant activities in vitro of the flavanolic polyphenols, the catechins, and catechin-gallate esters. The relative antioxidant potentials were measured against radicals generated in the aqueous phase and against propagating lipid peroxyl radicals. The results show that in the aqueous phase their order of effectiveness as radical scavengers is epicatechin gallate (ECG) > epigallocatechin gallate (EGCG) > epigallocatechin (EGC) > gallic acid (GA) > epicatechin congruent to catechin; against propagating lipid peroxyl radical species, epicatechin and catechin are as effective as ECG and EGCG, the least efficacious being EGC and GA. This is consistent with their relative abilities to protect against consumption of LDL alpha-tocopherol. The results are discussed in the context of the most relevant antioxidant constituents of green tea extracts.

264. Carcinogenesis 1995 Feb;16(2):217-21

Chemoprevention of 2-amino-1-methyl-6-phenylimidazo[4,5-b]-pyridine (PhIP)-induced mammary gland carcinogenesis by antioxidants in F344 female rats.

Hirose M, Akagi K, Hasegawa R, Yaono M, Satoh T, Hara Y, Wakabayashi K, Ito N

First Department of Pathology, Nagoya City University, Medical School, Japan.

Chemopreventive effects of the antioxidants 1-O-hexyl-2,3,5- trimethylhydroquinone (HTHQ), 3-O-ethylascorbic acid (EAsA), 3-O-dodecylcarbomethylascorbic acid (DAsA), green tea catechins (GTC) and ellagic acid on 2-amino-1-methyl-6- phenylimidazo[4,5-b]pyridine (PhIP)-induced mammary carcinogenesis were examined in female F344 rats. Groups of 20-21 6-week-old rats were maintained on a powdered diet containing 0.02% PhIP alone, PhIP together with 0.5% HTHQ, 1% EAsA, 1% DAsA, 1% GTC or 0.1% ellagic acid, these antioxidants alone or basal diet alone without supplement for 52 weeks. The survival rates of PhIP plus antioxidant groups at the end of the experiment were higher than that of the PhIP alone group. Sequential observation of palpable mammary tumors demonstrated only one tumor by week 52 in the PhIP plus HTHQ group, whereas 40% of the rats receiving PhIP alone had tumors by this time point. The final incidence of mammary adenocarcinomas was significantly decreased in the PhIP plus HTHQ group (4.8%, P < 0.01) as compared to the PhIP alone value (40%). Although statistically not significant, incidences of adenocarcinomas in the other antioxidant-treated groups (23.8-28.6%) were also lower than in the PhIP alone group. Furthermore, the incidence of large intestinal tumors in the PhIP plus HTHQ group (0%) showed a tendency to decrease relative to the PhIP alone group (16.7%). These results indicate that antioxidants, particularly HTHQ, exert a potent chemopreventive action against PhIP-induced carcinogenesis.

265. J Cell Biochem Suppl. 1995;22:169-80.

Polyphenols as cancer chemopreventive agents.

Stoner GD, Mukhtar H.

Department of Preventive Medicine, Ohio State University, Columbus 43210, USA.

This article summarizes available data on the chemopreventive efficacies of tea polyphenols, curcumin and ellagic acid in various model systems. Emphasis is placed upon the anticarcinogenic activity of these polyphenols and their proposed mechanism(s) of action. Tea is grown in about 30 countries and, next to water, is the most widely consumed beverage in the world. Tea is manufactured as either green, black, or oolong; black tea represents approximately 80% of tea products. Epidemiological studies, though inconclusive, suggest a protective effect of tea consumption on human cancer. Experimental studies of the antimutagenic and anticarcinogenic effects of tea have been conducted principally with green tea polyphenols (GTPs). GTPs exhibit antimutagenic activity in vitro, and they inhibit carcinogen-induced skin, lung, forestomach, esophagus, duodenum and colon tumors in rodents. In addition, GTPs inhibit TPA-induced skin tumor promotion in mice. Although several GTPs possess anticarcinogenic activity, the most active is (-)-epigallocatechin-3-gallate (EGCG), the major constituent in the GTP fraction. Several mechanisms appear to be responsible for the tumor-inhibitory properties of GTPs, including enhancement of antioxidant (glutathione peroxidase, catalase and quinone reductase) and phase II (glutathione-S-transferase) enzyme activities; inhibition of chemically induced lipid peroxidation; inhibition of irradiation- and TPA-induced epidermal ornithine decarboxylase (ODC) and cyclooxygenase activities; inhibition of protein kinase C and cellular proliferation; antiinflammatory activity; and enhancement of gap junction intercellular communication. Curcumin is the yellow coloring agent in the spice tumeric. It exhibits antimutagenic activity in the Ames Salmonella test and has anticarcinogenic activity, inhibiting chemically induced preneoplastic lesions in the breast and colon and neoplastic lesions in the skin, forestomach, duodenum and colon of rodents. In addition, curcumin inhibits TPA-induced skin tumor promotion in mice. The mechanisms for the anticarcinogenic effects of curcumin are similar to those of the GTPs. Curcumin enhances glutathione content and glutathione-S-transferase activity in liver; and it inhibits lipid peroxidation and arachidonic acid metabolism in mouse skin, protein kinase C activity in TPA-treated NIH 3T3 cells, chemically induced ODC and tyrosine protein kinase activities in rat colon, and 8-hydroxyguanosine formation in mouse fibroblasts. Ellagic acid is a polyphenol found abundantly in various fruits, nuts and vegetables. Ellagic acid is active in antimutagenesis assays, and has been shown to inhibit chemically induced cancer in the lung, liver, skin and esophagus of rodents, and TPA-induced tumor promotion in mouse skin.

266. The tea plant - Camellia sinensis (L.)O. Kuntze CAMELLIA SINENSIS (L.) O. KUNTZE. DER TEESTRAUCH Scholz E.; Bertram B. Inst. fur Pharmazeutische Biologie, Albert-Ludwigs-Universitat, Schanzlestrasse 1, 79104 Freiburg Germany Zeitschrift fur Phytotherapie (Germany) , 1995, 16/4 (231-238+241-246)

The worldwide consumption of tea as a beverage is second only to that of water. Tea is obtained from young leaves and buds of Camellia sinensis (L.) O. Kuntze, indigenous to mountainous regions of Southeast Asia and cultivated in East Asia for more than 2000 years. green tea is manufactured by rapid heating followed by drying of freshly harvested leaves. Fermentation of the withered, rolled and crushed fresh leaves at high humidity gives black tea. Besides caffeine, which is present in both tea qualities, green tea contains high quantities of flavanols (catechins), flavonol glycosides, small amounts of condensed and hydrolysable tannins, and saponins. Tannin related, coloured oxidation products of flavanols, particularly the poorly characterized thearubigens, prevail in black tea, which also contains theaflavins, small amounts of theaflagallins and bisflavanols (theasinensins), and unchanged flavonol glycosides. In both tea qualities, unusually high levels of fluorides and aluminium are found. Consumption of green and black tea has been reported to be beneficial to human health. Many laboratory studies have demonstrated inhibitory effects of tea preparations and tea polyphenols against tumor formation and growth, and there is some evidence from epidemiologic studies, that tea may have a protective effect on certain cancers. This effect is believed to be mainly due to antioxidative properties of the tea polyphenols, coupled with their ability to inhibit carcinogen activating enzymes and to suppress endogenous formation of N-nitroso compounds. In addition, virostatic, bacteristatic and reverse-transcriptase-inhibitive, as well as antiatherosclerotic effects are reported. Green tea extracts and flavanols decrease blood pressure, plasma glucose and cholesterol levels in vivo, inhibit platelet aggregation in vitro, and seem to lower the risk of coronary heart disease.

267. Chest 1994 Dec;106(6):1801-5

Epigallocatechin gallate. The major causative agent of green tea-induced asthma.

Shirai T, Sato A, Hara Y

Department of Internal Medicine, Hamamatsu University School of Medicine, Japan.

We describe three patients who worked in green tea factories and developed asthmatic and nasal symptoms after exposure to green tea dust. To clarify what component(s) of green tea leaves might be responsible for causing asthma, we prepared catechins, the major components of green tea leaves. Epigallocatechin gallate (EGCg; MW: 458 daltons), a major catechin, was purified by high-performance liquid chromatography. Subjects included three patients with green tea-induced asthma, five asthmatics with no previous exposure to tea dust, and five healthy controls. It was found that all three patients exhibited an immediate skin and bronchial response to EGCg. Prausnitz-Kustner test with EGCg was also positive. However, none of the asthmatic and healthy controls showed a positive reaction. These results indicate that EGCg is a causative agent of green tea-induced asthma and suggest that an IgE-mediated response is, at least in part, responsible for causing this type of occupational asthma.

268. Plant Foods Hum Nutr. 1994 Oct;46(3):221-9.

Green and black tea consumption by humans: impact on polyphenol concentrations in feces, blood and urine.

He YH, Kies C.

Department of Nutritional Science and Dietetics, University of Nebraska, Lincoln 68583-0807.

The objective of the study was to determine the effects of green tea, black tea and decaffeinated black tea consumption on urinary and fecal excretions and whole blood and blood serum concentrations of polyphenols. The 56 day study was divided into four randomly arranged experimental periods of 14 days each during which the 10 healthy adult subjects consumed a laboratory controlled, constant, measured diet based on ordinary foods. During separate periods, subjects received no tea, green tea, regular black tea or decaffeinated black tea beverages at the three daily meals. Subjects made complete collections of urine and stools throughout the study and fasting blood samples were drawn at the beginning of the study and at the end of each experimental period. Polyphenols contained in urine, feces, whole blood, blood serums, food and tea were analyzed by the spectrophotometry method of Wah Lau et al. (1989). Green tea consumption resulted in highest intakes in greatest fecal and urinary excretions, highest retentions, and high whole blood concentrations of polyphenols followed by effects of regular black tea, decaffeinated black tea and no tea treatments. These results indicate that polyphenols from tea are at least partly absorbable. Hence, both positive and negative effects of dietary polyphenol may occur internal to the body proper and not only as effects within the intestines.

269. Cancer Lett 1994 Aug 15;83(1-2):149-56

Inhibition of mammary gland carcinogenesis by green tea catechins and other naturally occurring antioxidants in female Sprague-Dawley rats pretreated with 7,12-dimethylbenz[alpha]anthracene.

Hirose M, Hoshiya T, Akagi K, Futakuchi M, Ito N

First Department of Pathology, Nagoya City University, Medical School, Japan.

Effects of the naturally occurring antioxidants on mammary gland carcinogenesis were examined in female Sprague-Dawley rats pretreated with 7,12-dimethylbenz[alpha]anthracene (DMBA). Groups of 15-16 7-week-old rats received a 50 mg/kg body weight intra-gastric dose of DMBA, and starting one week thereafter placed on diet containing 0.4% catechol, 1.0% gamma-oryzanol, 2.0% phytic acid, 1.0% green tea catechins (GTC), 1.0% tannic acid or basal diet alone for 35 weeks. Although the final incidences and multiplicities of mammary tumors were not significantly different between DMBA-treated groups, the numbers of survivors in the antioxidant-treated groups at the end of the experiment at week 36 were significantly higher than in the basal diet group. In particular, the survival rate of the GTC group at 93.8% strongly contrasted with that of only 33.3% for rats on the basal diet. At the end of week 18, when all the animals were still alive, the average size of palpable mammary tumors was significantly smaller in the catechol, phytic acid and catechins groups. These results indicate that antioxidants, and GTC in particular, inhibit rat mammary gland carcinogenesis after DMBA initiation.

270. Cancer Lett 1994 Apr 29;79(1):33-8

Experimental studies of the inhibitory effects of green tea catechin on mice large intestinal cancers induced by 1,2-dimethylhydrazine.

Yin P, Zhao J, Cheng S, Zhu Q, Liu Z, Zhengguo L

Department of Pathology, Henan Provincial Hospital, China.

Three hundred Kunming mice were randomly divided into six groups (half males and half females in each group). Group 1 was the positive control group, Groups 2, 3, 4 and 5 were experimental groups and Group 6 was used as the solvent control group. Mice in Groups 1-4 were injected with 1,2-dimethylhydrazine (1,2-DMH) (20 mg/kg body wt.) solution subcutaneously once a week from the 2nd week to the 20th week. From the 1st week to the 23rd week, mice in Groups 2, 3 and 4 were given catechin (1 mg/mouse), catechin (2 mg/mouse) and EGCG (2 mg/mouse), respectively, five times a week. Mice in Group 5 received only catechin (3 mg/mouse) five times a week from the 1st to the 23rd week. Mice in Group 6 were injected with an equal volume of 1 mmol EDTA solution subcutaneously once a week from the 2nd to the 20th week. At the end of the 27th week, all the mice were killed by cervical dislocation (Zhu, Q.H. and Zhu, Q.F. (1991) Laboratory Animal Science, 1st edition. The Junior Educational Publisher, Guangdong). Pathological examinations indicated that the incidence of large intestinal cancers occurring in Group 1 was 80%, significantly higher than that in Groups 2, 3 and 4 (p < 0.001). No tumors were found in Groups 5 and 6. This might suggest that green tea has preventive effects on large intestinal cancer induction in spite of the different doses of catechin. Immunohistochemistry studies showed that green tea catechins could enhance the activity of superoxide dismutase (SOD) in tissues.

271. Cancer Res. 1994 Jul 1;54(13):3428-35.

Inhibitory effects of black tea, green tea, decaffeinated black tea, and decaffeinated green tea on ultraviolet B light-induced skin carcinogenesis in 7,12-dimethylbenz[a]anthracene-initiated SKH-1 mice.

Wang ZY, Huang MT, Lou YR, Xie JG, Reuhl KR, Newmark HL, Ho CT, Yang CS, Conney AH.

Department of Chemical Biology and Pharmacognosy, College of Pharmacy, Rutgers, State University of New Jersey, Piscataway 08855-0789.

In a previous study (Z. Y. Wang et al., Cancer Res., 52: 1162-1170, 1992), we found that administration of a water extract of green tea leaves as the sole source of drinking fluid inhibited ultraviolet B light (UVB)-induced carcinogenesis in SKH-1 mice previously initiated with 7,12-dimethylbenz[a]anthracene (DMBA). In the present study, we compared the effects of black tea, green tea, decaffeinated black tea, and decaffeinated green tea on UVB-induced skin carcinogenesis in DMBA-initiated SKH-1 mice. A 1.25% water extract of each kind of tea leaf (1.25 g tea leaf/100 ml water) was prepared by passing 4 liters of hot water through 50 g of tea leaves in a Bunn tea brewing machine. The mean concentrations of solids in multiple samples of 1.25% black tea, green tea, decaffeinated black tea, and decaffeinated green tea analyzed during the course of this study were 4.23, 3.94, 3.66, and 3.53 mg/ml, respectively. These concentrations of tea solids are similar to those present in tea brews ingested by humans. Female SKH-1 mice were treated topically with 200 nmol of DMBA, followed 3 weeks later by irradiation with 30 mJ/cm2 of UVB twice weekly for 31 weeks. UVB-induced formation of skin tumors was markedly inhibited by oral administration of 0.63 or 1.25% black tea, green tea, decaffeinated black tea, or decaffeinated green tea as the sole source of drinking fluid 2 weeks prior to and during 31 weeks of UVB treatment. Administration of each of the eight tea preparations not only inhibited the number of tumors, but tumor size was also markedly decreased. Histopathological examination of each tumor showed that oral administration of the eight tea preparations had a marked inhibitory effect on the formation of UVB-induced keratoacanthomas and carcinomas. Administration of 1.25% black tea, green tea, decaffeinated black tea, or decaffeinated green tea inhibited the number of keratoacanthomas per mouse by 79, 78, 73, or 70%, respectively, and the number of carcinomas per mouse was inhibited by 93, 88, 77, or 72%, respectively. In summary, administration of black tea was comparable to green tea as an inhibitor of UVB-induced skin carcinogenesis in DMBA-initiated SKH-1 mice. Oral administration of decaffeinated black tea or decaffeinated green tea also had a marked inhibitory effect on UVB-induced skin carcinogenesis in DMBA-initiated SKH-1 mice, but these tea preparations were slightly less effective than the regular teas at the high dose level.

272. Carcinogenesis 1993 Aug;14(8):1549-53

Effects of green tea catechins in a rat multi-organ carcinogenesis model.

Hirose M, Hoshiya T, Akagi K, Takahashi S, Hara Y, Ito N

First Department of Pathology, Nagoya City University Medical School, Japan.

The effects of dietary administration of green tea catechins (GTC) were examined using a multi-organ carcinogenesis model. Groups of 15 F344 male rats were initially treated with a single i.p. administration of 100 mg/kg body wt N-diethyl-nitrosamine, 4 i.p. administrations of 20 mg/kg body wt N-methylnitrosourea, 4 s.c. doses of 40 mg/kg body wt 1,2-dimethylhydrazine, together with 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine for 2 weeks and then 0.1% 2,2'-dihydroxy-di-n-propylnitrosamine for 2 weeks, both in the drinking water, for a total initiation period of 4 weeks. GTC in the diet, at doses of 1.0 or 0.1%, was administered from 1 day before and during carcinogen exposure, after carcinogen exposure or both during and after carcinogen exposure. Further groups of animals were treated with carcinogen, 1% GTC or basal diet alone as controls. All animals were killed at the end of week 36, and all major organs examined histopathologically. The numbers of small intestinal tumors (adenomas and carcinomas) per rat were significantly reduced in the groups treated with 1% GTC during (0.13 +/- 0.35) and after carcinogen exposure (0.31 +/- 0.48) and in those receiving 1% and 0.1% GTC both during and after carcinogen exposure (0.14 +/- 0.36, 0.46 +/- 0.97 respectively) as compared with the carcinogen alone group (1.07 +/- 1.21). On the other hand, numbers of glutathione S-transferase placental form positive liver foci per cm2 were slightly but significantly increased in the groups treated with 1 and 0.1% GTC during carcinogen exposure, 1% GTC after carcinogen exposure and 1% GTC both during and after carcinogen exposure. The results indicated that while GTC inhibits small intestinal carcinogenesis it slightly enhances hepatocarcinogenesis in a dose dependent manner when applied both during and after carcinogen exposure.

273. J Periodontol 1993 Jul;64(7):630-6

Inhibitory effect of tea catechins on collagenase activity.

Makimura M, Hirasawa M, Kobayashi K, Indo J, Sakanaka S, Taguchi T, Otake S

Nihon University School of Dentistry at Matsudo, Department of Clinical Pathology, Japan.

A major purpose of this study was to examine inhibitory effect of the catechin derivatives from Japanese green tea Camellia sinensis on collagenase activity. The crude tea catechins, which contain (+)-catechin (C), (-)-epicatechin (EC), (+)-gallocatechin (GC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECg), and (-)-epigallocatechin gallate (EGCg), were tested for their ability to inhibit the prokaryotic and eukaryotic cell derived collagenase activities. Among the tea catechins tested, ECg and EGCg showed the most potent inhibitory effect on collagenase activity when an optimal concentration of tea catechins (100 micrograms/ml) was added to reaction mixture containing collagenase and collagen. Preincubation of collagenase with tea catechins reduced the collagenase activity as well. In contrast to ECg and EGCg, the other four tea catechins (C, EC, EGC, and GC) did not show any collagenase inhibitory effect. Our results suggest that the steric structure of 3-galloyl radical is important for the inhibition of collagenase activity. The collagenase activity in the gingival crevicular fluid from highly progressive adult periodontitis was completely inhibited by the addition of tea catechins. These results demonstrated that tea catechins containing galloyl radical possess the ability to inhibit both eukaryotic and prokaryotic cell derived collagenase.

274. Carcinogenesis. 1993 May;14(5):849-55.

Protection against N-nitrosodiethylamine and benzo[a]pyrene-induced forestomach and lung tumorigenesis in A/J mice by green tea.

Katiyar SK, Agarwal R, Zaim MT, Mukhtar H.

Department of Dermatology, University Hospitals of Cleveland, Case Western Reserve University, OH.

In recent years we and others have shown the cancer chemopreventive effects of green tea in several animal tumor models. In this study we assessed the cancer chemopreventive effects of water extract of green tea (WEGT) and the polyphenolic fraction (GTP) isolated from WEGT against N-nitrosodiethylamine (DEN)- and benzo[a]pyrene (BP)-induced forestomach and lung tumorigenesis in A/J mice. The protective effects, both in forestomach and lungs, were evident by a decrease in number of tumors and the percentage of mice with tumors when WEGT and GTP were fed to animals during initiation, post-initiation and entire period of tumorigenesis protocols. Oral feeding of 0.2% GTP in drinking water to mice afforded 68-82 and 39-66% protection against DEN- and BP-induced forestomach tumorigenesis respectively. In case of pulmonary tumor multiplicity caused by DEN and BP, the protective effects of GTP were between 38-43 and 25-46% respectively. Similarly, oral feeding of 2.5% WEGT to mice also afforded 80-85 and 61-71% protection against DEN- and BP-induced forestomach tumorigenesis respectively. In case of lung tumorigenesis, the protective effects of WEGT were 43-62 and 25-51% respectively. Histological studies of forestomach tumors showed significantly lower squamous cell carcinoma counts in GTP- and WEGT-fed groups of mice compared to carcinogen alone treated control group of mice. When pulmonary tumors were examined histologically, no adenocarcinomas were observed in GTP- and WEGT-fed groups of mice compared to 20% mice with adenocarcinomas in carcinogen alone treated control group. Oral feeding of GTP and WEGT in drinking water also showed significant enhancement in the activities of glutathione S-transferase and NADP(H): quinone reductase in liver, small bowel, stomach and lung. The results of this study suggest that green tea possesses chemopreventive effects against carcinogen-induced tumorigenesis in internal body organs, and that the mechanism of such effects may involve the enhancement of phase II and anti-oxidant enzyme systems.

275. Cancer Lett. 1993 Apr 15;69(1):15-9.

Enhancement of gap junctional intercellular communication in tumor promoter-treated cells by components of green tea.

Sigler K, Ruch RJ.

Department of Pathology, Medical College of Ohio, Toledo 43699.

Green tea (Camellia sinensis) has been reported to inhibit tumor promotion in vivo and in vitro. Many tumor promoters inhibit gap junctional intercellular communication (GJIC) which may be an important mechanism of promotion. In the present study, we hypothesized that green tea would enhance GJIC in promoter-treated cells. An aqueous extract of green tea (GTE) and several of its constituents were tested for their effects on GJIC in p,p'-dichlorodiphenyltrichloroethane (DDT)-, 12-O-tetradecanoylphorbol-13-acetate (TPA)- and dieldrin-treated WB-F344 rat liver epithelial cells. All three promoters inhibited GJIC in a dose-responsive manner at non-cytolethal concentrations. (GTE (10-80 gamma/ml) enhanced GJIC 20-80% in promoter-treated cells. (-)-Epigallocatechin gallate and (-)-epicatechin gallate also enhanced GJIC in DDT-treated cells, but no effects were seen with (+)-catechin, (-)-epicatechin, (-)-epigallocatechin, caffeine, or theobromine. These data suggest GTE may inhibit tumor promotion by enhancing GJIC and that the most active components are the catechin gallates.

276, Biochim Biophys Acta 1993 Apr 8;1147(1):132-6

Bactericidal catechins damage the lipid bilayer.

Ikigai H, Nakae T, Hara Y, Shimamura T

Department of Molecular Life Science, Tokai University School of Medicine, Isehara, Japan.

The mode of antibacterial action of, the green tea (Camellia sinensis) extracts, (-)-epigallocatechin gallate (EGCg) and (-)-epicatechin (EC) was investigated. Strong bactericidal EGCg caused leakage of 5,6-carboxyfluorescein from phosphatidylcholine liposomes (PC), but EC with very weak bactericidal activity caused little damage to the membrane. Phosphatidylserine and dicetyl phosphate partially protected the membrane from EGCg-mediated damage when reconstituted into the liposome membrane with PC. EGCg, but not EC, caused strong aggregation and NPN-fluorescence quenching of PC-liposomes and these actions were markedly lowered in the presence of negatively charged lipids. These results show that bactericidal catechins primarily act on and damage bacterial membranes. The observation that Gram-negative bacteria are more resistant to bactericidal catechins than Gram-positive bacteria can be explained to some extent by the presence of negatively charged lipopolysaccharide.

277. Int J Immunopharmacol 1992 Nov;14(8):1399-407

Mitogenic activity of (-)epigallocatechin gallate on B-cells and investigation of its structure-function relationship.

Hu ZQ, Toda M, Okubo S, Hara Y, Shimamura T

Department of Microbiology and Immunology, Showa University School of Medicine, Tokyo, Japan.

(-)Epigallocatechin gallate (EGCg), the main constituent of green tea, strongly enhanced the direct plaque-forming cell (PFC) response to sheep red blood cells (SRBC) in vitro and showed strong mitogenic activity for mouse splenic B-cells but not for splenic T-cells and thymocytes. The enhancement of B-cell proliferation was not mediated by macrophages since their removal did not eliminate the activity. Among the derivatives of catechin examined, (+)catechin (C); (-)epicatechin (EC); (-)-epigallocatechin (EGC); (-)epicatechin gallate (ECg); (-)epigallocatechin gallate (EGCg); and theaflavin digallate (TF3), only the derivatives with the galloyl group (ECg, EGCg, and TF3) displayed significant enhancement of the spontaneous proliferation of B-cells. Structural analogs of the catechin and galloyl groups were also examined in the system. Gallic acid and tannic acid induced some enhancement, but rutin, pyrogallol and caffeine did not. The results indicate that the galloyl group on EGCg was responsible for enhancement. However, the basic conformations of the catechins are also important, because ECg, EGCg, TF3, gallic acid, and tannic acid had quite different potencies to induce B-cell proliferation.

278. Prev Med. 1992 May;21(3):361-9.

Inhibitory effect of green tea on tumorigenesis by chemicals and ultraviolet light.

Conney AH, Wang ZY, Huang MT, Ho CT, Yang CS.

Department of Chemical Biology and Pharmacognosy, College of Pharmacy, Rutgers, State University of New Jersey, Piscataway 08854.

Topical application of a green tea polyphenol fraction inhibited 12-O-tetradecanoyl-phorbol-13-acetate-induced tumor promotion in CD-1 mice previously initiated with 7,12-dimethylbenz[a]anthracene (DMBA). Oral administration of a green tea infusion as the sole source of liquid sustenance to SKH-1 mice inhibited ultraviolet B light (UVB)-induced sunburn lesions, UVB-induced initiation of skin tumors, UVB-induced formation of skin tumors in mice previously initiated with DMBA, and nitrosodiethylamine-induced forestomach and lung tumors in A/J mice. In addition to inhibiting UVB-induced formation of skin tumors in DMBA-initiated mice, oral administration of green tea markedly decreased tumor size.

279. Cancer Res. 1992 Jul 15;52(14):3875-9.

Inhibition of tobacco-specific nitrosamine-induced lung tumorigenesis in A/J mice by green tea and its major polyphenol as antioxidants.

Xu Y, Ho CT, Amin SG, Han C, Chung FL.

American Health Foundation, Valhalla, New York 10595.

In this study we examined the effects of green tea and its major components, (-)-epigallocatechin gallate (EGCG) and caffeine, on the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung tumorigenesis in A/J mice. We also studied the effects of green tea and EGCG on O6-methylguanine and 8-hydroxydeoxyguanosine (8-OH-dGuo) formation in lung tissues caused by NNK treatment. Mice were given 2% tea, 560 ppm EGCG, or 1120 ppm caffeine in drinking water for 13 weeks. During this time, NNK (11.65 mg/kg body weight) was administered by gavage three times weekly for 10 weeks from weeks 3 to 12. The bioassay was terminated 6 weeks after the last NNK treatment. Mice treated with NNK developed 22.5 lung adenomas per mouse, whereas NNK-treated mice that drank green tea or EGCG as drinking water developed only 12.2 (P less than 0.01) and 16.1 (P less than 0.05) tumors per mouse, respectively. Mice that drank green tea or caffeine solution showed lower body weight gains, although little difference in water and diet consumption was noted in these groups. While green tea and EGCG exerted little effect on the formation of O6-methylguanine, a critical DNA lesion in NNK lung tumorigenesis, both treatments suppressed the increase of 8-OH-dGuo levels in mouse lung DNA. The inhibition of 8-OH-dGuo formation in lung DNA by green tea and EGCG is consistent with their ability to inhibit lung tumorigenesis by NNK. Because 8-OH-dGuo is a DNA lesion caused by oxidative damage, these results suggest that the mechanism of inhibition by green tea and EGCG in NNK-induced lung tumorigenesis is due at least partly to their antioxidant properties.

280. Prev Med. 1992 May;21(3):351-60.

Tea components: antimutagenic and anticarcinogenic effects.

Mukhtar H, Wang ZY, Katiyar SK, Agarwal R.

Department of Dermatology, University Hospitals of Cleveland, Case Western Reserve University, Ohio.

BACKGROUND. Tea from the Camellia sinensis species of the Theaceae family is one of the most ancient and, next to water, the most widely consumed beverage in the world. Since tea contains several polyphenols and since several other naturally occurring dietary polyphenols have shown antimutagenic effects in bacteria and anticarcinogenic effects in animal bioassay systems, we studied whether polyphenols extracted from Chinese green tea (GTP) also possess antimutagenic and anticarcinogenic effects. RESULTS. GTP and its constituent epicatechin derivatives were found to interact with hepatic cytochrome P450 (P450) and inhibited the P450-dependent mixed-function oxidase enzymes in skin and liver. GTP and its epicatechin derivatives exhibited antimutagenic effects in several test systems. GTP showed substantial anti-skin-tumor-initiating and anti-skin-tumor-promoting activities when assessed in murine skin tumorigenesis bioassay systems. In these model systems polyaromatic hydrocarbons, benzo[a]pyrene (BP), 3-methyl-cholanthrene, 7,12-dimethylbenz[a]anthracene, and (+)-7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10- tetrahydrobenzo[a]pyrene (an ultimate carcinogenic metabolite of BP) were used as model skin carcinogens. The feeding of GTP in drinking water to SKH-1 hairless mice also afforded significant protection against ultraviolet-B-radiation-induced skin photocarcinogenesis. CONCLUSIONS. These data suggest that tea components possess antimutagenic and anticarcinogenic effects, and that they could protect humans against the risk of cancer by environmental agents.

281. Prev Med 1992 May;21(3):334-50

Green tea composition, consumption, and polyphenol chemistry.

Graham HN

Tea is grown in about 30 countries but is consumed worldwide, although at greatly varying levels. It is the most widely consumed beverage aside from water with a per capita worldwide consumption of approximately 0.12 liter per year. Tea is manufactured in three basic forms. green tea is prepared in such a way as to preclude the oxidation of green leaf polyphenols. During black tea production oxidation is promoted so that most of these substances are oxidized. Oolong tea is a partially oxidized product. Of the approximately 2.5 million metric tons of dried tea manufactured, only 20% is green tea and less than 2% is oolong tea. Green tea is consumed primarily in China, Japan, and a few countries in North Africa and the Middle East. Fresh tea leaf is unusually rich in the flavanol group of polyphenols known as catechins which may constitute up to 30% of the dry leaf weight. Other polyphenols include flavanols and their glycosides, and depsides such as chlorogenic acid, coumarylquinic acid, and one unique to tea, theogallin (3-galloylquinic acid). Caffeine is present at an average level of 3% along with very small amounts of the other common methylxanthines, theobromine and theophylline. The amino acid theanine (5-N-ethylglutamine) is also unique to tea. Tea accumulates aluminum and manganese. In addition to the normal complement of plant cell enzymes, tea leaf contains an active polyphenol oxidase which catalyzes the aerobic oxidation of the catechins when the leaf cell structure is disrupted during black tea manufacture. The various quinones produced by the enzymatic oxidations undergo condensation reactions which result in a series of compounds, including bisflavanols, theaflavins, epitheaflavic acids, and thearubigens, which impart the characteristic taste and color properties of black tea. Most of these compounds readily form complexes with caffeine. There is no tannic acid in tea. Thearubigens constitute the largest mass of the extractable matter in black tea but their composition is not well known. Proanthocyanidins make up part of the complex. Tea peroxidase may be involved in their generation. The catechin quinones also initiate the formation of many of the hundreds of volatile compounds found in the black tea aroma fraction. green tea composition is very similar to that of the fresh leaf except for a few enzymatically catalyzed changes which occur extremely rapidly following plucking. New volatile substances are produced during the drying stage. Oolong tea is intermediate in composition between green and black teas.

282. Kansenshogaku Zasshi 1992 May;66(5):606-11

[Antimicrobial and microbicidal activities of tea and catechins against Mycoplasma].

[Article in Japanese]

Chosa H, Toda M, Okubo S, Hara Y, Shimamura T

Department of Microbiology and Immunology, Showa University School of Medicine.

We examined tea extracts, (-) epigallocatechin gallate (EGCg) and theaflavin digallate (TF3) for their antimicrobial and microbicidal activities against Mycoplasma. green tea and black tea showed antimicrobial activities against M. pneumoniae. At a concentration of 0.2% green tea and black tea showed microbicidal activities against M. pneumoniae and M. orale but not against M. salivarium. Extracts of pu-erh tea showed a slight microbicidal activity against M. pneumoniae and M. orale. EGCg purified from green tea and TF3 from black tea markedly showed microbicidal activities against M. pneumoniae. M. orale and M. salivarium. These results suggest that tea and catechins can be used as prophylactic agents against Mycoplasma pneumoniae infection.

283. Kansenshogaku Zasshi 1992 May;66(5):599-605

[Protective activity of tea and catechins against Bordetella pertussis].

[Article in Japanese]

Horiuchi Y, Toda M, Okubo S, Hara Y, Shimamura T

Department of Microbiology and Immunology, Showa University School of Medicine.

We examined the bactericidal activity of tea and catechins against Bordetella pertussis. Green tea, black tea and coffee showed marked bactericidal activity at their concentrations in beverages, while pu-erh tea killed the bacteria in a moderate way. (-) epigallocatechin gallate (EGCg) and theaflavin digallate (TF3) showed also marked bactericidal activity. green tea and black tea also effectively blocked the adhesion of B. pertussis to HeLa and CHO cells, whereas ECGg and TF3 could not. EGCg and TF3 markedly inactivated leuco-lymphocytosis promoting activity of pertussis toxin. Black tea showed slight but significant inactivation of the activity, whereas green tea showed no inactivation. These results suggest that green tea, black tea, EGCg and TF3 might act as prophylactic agents against pertussis infection.

284. Cancer Res. 1992 Mar 1;52(5):1162-70.

Inhibitory effect of green tea in the drinking water on tumorigenesis by ultraviolet light and 12-O-tetradecanoylphorbol-13-acetate in the skin of SKH-1 mice.

Wang ZY, Huang MT, Ferraro T, Wong CQ, Lou YR, Reuhl K, Iatropoulos M, Yang CS, Conney AH.

Department of Chemical Biology and Pharmacognosy, College of Pharmacy, Rutgers, State University of New Jersey, Piscataway 08855.

Green tea was prepared by extracting 12.5 g of green tea leaves twice with 500 ml of boiling water, and the extracts were combined. This 1.25% green tea extract (1.25 g of tea leaves/100 ml of water) contained 4.69 mg of green tea extract solids per ml and was similar in composition to some green tea beverages consumed by humans. A 2.5% green tea extract (2.5 g of tea leaves/100 ml of water) was prepared similarly. Treatment of female SKH-1 mice with 180 mJ/cm2 of ultraviolet B light (UVB) once daily for 7 days resulted in red sunburn lesions of the skin. The intensity of red color and area of these lesions were inhibited in a dose-dependent fashion by the administration of 1.25 or 2.5% green tea extract as the sole source of drinking water before and during UVB treatment. Treatment of female SKH-1 mice with 180 mJ/cm2 of UVB once daily for 10 days followed 1 wk later by twice weekly application of 12-O-tetradecanoylphorbol-13-acetate for 25 wk resulted in the development of skin tumors. The formation of skin tumors was inhibited by administration of 1.25% green tea extract as the sole source of drinking water prior to and during the 10 days of UVB treatment and for 1 wk after UVB treatment. In additional experiments, female SKH-1 mice were treated with 200 nmol of 7,12-dimethylbenz(a)anthracene followed 3 wk later by irradiation with 180, 60, or 30 mJ/cm2 of UVB twice weekly for 30 wk. UVB-induced formation of skin tumors and increased spleen size were inhibited by administration of 1.25% green tea extract as the sole source of drinking water prior to and during the 30 wk of UVB treatment. In these experiments, treatment of the animals with the green tea extract not only decreased the number of skin tumors but also decreased substantially the size of the tumors. In additional studies, SKH-1 mice were initiated by topical application of 200 nmol of 7,12-dimethylbenz(a)anthracene followed by twice weekly application of 12-O-tetradecanoylphorbol-13-acetate for 25 wk. Administration of 1.25% green tea extract as the sole source of drinking water during promotion with 12-O-tetradecanoylphorbol-13-acetate reduced the number and incidence of skin tumors.

285. Teratog Carcinog Mutagen 1992;12(2):79-95

Strategy of research for cancer--chemoprevention.

Ito N, Imaida K

First Department of Pathology, Nagoya City University Medical School, Japan.

It has been reported that environmental chemicals are important factors in terms of both development and prevention of human cancer. For the latter, detection of early stages is an essential first step followed by clinical trials for surveying populations at risk. Thus a great deal of attention has been focused on these areas. However, investigations of possibilities for active prevention of cancer development itself form another major project. Chemoprevention of carcinogenesis, which means prevention of carcinogenesis by exogenous chemical compounds, has been investigated extensively in a variety of organs in animal models. Usually attention is concentrated on only one organ. However, antioxidants, such as BHA, exert very different effects on different organs, suggesting the necessity of whole body approaches to the question of chemoprevention. Furthermore, the mechanisms of chemoprevention, including the step of carcinogenesis, i.e., initiation, promotion, progression or whole carcinogenesis steps, in which exogenous compounds exert their protective effects, should be considered. A medium-term bioassay system and a multi-organ carcinogenesis system, which can be used for investigation of potential for cancer chemoprevention, have been developed in our laboratory. Dose dependent inhibitory effects were established for both BHA and alpha-tocopherol in the medium-term bioassay system, and inhibition of small intestinal carcinogenesis by catechins in green tea has also been investigated in our multi-organ carcinogenesis protocol. It is extremely important for prevention of human cancer that we find new candidates for chemopreventive agents using animal studies. This paper reviews published reports on chemoprevention, taking into account effective stages, and proposes suitable experimental animal models for future investigations in this increasingly important area.

286. Jpn J Med Sci Biol 1991 Aug;44(4):181-6 Inhibition of rotavirus and enterovirus infections by tea extracts. Mukoyama A, Ushijima H, Nishimura S, Koike H, Toda M, Hara Y, Shimamura T. Department of Enteroviruses, National Institute of Health, Tokyo, Japan.

Epigallocatechin gallate from green tea and theaflavin digallate from black tea inhibited infections of cultured rhesus monkey kidney MA 104 cells with rotaviruses and enteroviruses. Their antiviral effects were maximally induced when directly added to virus, and their pre- and post-treatment of the cells produced much weak antiviral activity. Antiviral activity of the extracts therefore seems to be attributable to interference with virus adsorption.

287. Caries Res 1991;25(6):438-43

Anticaries effects of polyphenolic compounds from Japanese green tea.

Otake S, Makimura M, Kuroki T, Nishihara Y, Hirasawa M

Department of Clinical Pathology, Nihon University School of Dentistry, Matsudo, Japan.

The dental caries inhibiting effect of the extract from Japanese green tea, one of the most popular drinks in Japan, was studied both in vitro and in vivo. The crude tea polyphenolic compounds (designated Sunphenon) from the leaf of Camellia sinensis were found to effectively inhibit the attachment of Streptococcus mutans strain JC-2 (serotype c) to saliva-coated hydroxyapatide discs. Sunphenon was also inhibitory to water-insoluble glucan formation from sucrose by crude glucosyltransferase of S. mutans JC-2 (c). Among the tea catechins tested, (-)-epigallocatechin gallate and (-)-epicatechin gallate showed the most potent inhibition of the glucosyltransferase activity. Finally, significantly lower caries scores were observed in specific pathogen free rats infected with S. mutans JC-2 (c) and fed a cariogenic diet and/or drinking water containing 0.05% Sunphenon as compared with control rats not receiving polyphenolic compounds.

288. Chem Pharm Bull (Tokyo) 1990 Mar;38(3):790-3

Platelet aggregation inhibitors in hot water extract of green tea.

Sagesaka-Mitane Y, Miwa M, Okada S

Ito-en Central Research Institute, Shizuoka, Japan.

The effect of hot water extract of green tea on the collagen-induced aggregation of washed rabbit platelets was examined. The extract lowered submaximal aggregation and prolonged the lag time in a dose-dependent manner. After fractionation of the extract, it was revealed that the tea catechins (tannins) are active principles for inhibition and that ester-type catechins are more effective than free-type catechins. One of the ester type catechins, epigallocatechin gallate (EGCG), suppressed the collagen-induced platelet aggregation completely at the concentration of 0.2 mg/ml (= 0.45 mM). Comparing IC50 values of EGCG and aspirin it was found that the potency of EGCG is comparable to that of aspirin. Thrombin- and platelet activating factor (PAF)-induced aggregation was also inhibited by EGCG. The elevation of cyclic adenosine 3',5'-monophosphate (cAMP) level was not observed in EGCG treated platelets.

289. Chem Pharm Bull (Tokyo). 1990 Mar;38(3):717-20.

Effect of tea polyphenols on glucan synthesis by glucosyltransferase from Streptococcus mutans.

Hattori M, Kusumoto IT, Namba T, Ishigami T, Hara Y.

Research Institute for Wakan-Yaku, Toyama Medical and Pharmaceutical University, Japan.

In the course of our studies on the development of anti-plaque agents for prevention of dental caries, we investigated effects of some of tea preparations and their individual components on the glucan synthesis catalyzed by glucosyltransferase (GTF) from Streptococcus mutans. Extracts of green tea and black tea, and polyphenol mixtures showed appreciable inhibition in the synthesis of insoluble glucan. Among the components isolated from tea infusions, theaflavin and its mono- and digallates had potent inhibitory activities at concentrations of 1-10 mM against GTF. (+)-Catechin, (-)-epicatechin and their enantiomers had moderate inhibitory activities at these concentrations, while galloyl esters of (-)-epicatechin, (-)-epigallocatechin and (-)-gallocatechin had increased inhibitory activities.

290. Carcinogenesis 1989 Jun;10(6):1003-8

Prevention of cytotoxicity and inhibition of intercellular communication by antioxidant catechins isolated from Chinese green tea.

Ruch RJ, Cheng SJ, Klaunig JE

Department of Pathology, Medical College of Ohio, Toledo 43699.

An antioxidant fraction of Chinese green tea (green tea antioxidant; GTA), containing several catechins, has been previously shown to inhibit 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced tumor promotion in mouse skin. In the present study, GTA was shown to have antioxidative activity toward hydrogen peroxide (H2O2) and the superoxide radical (O2-). GTA also prevented oxygen radical and H2O2-induced cytotoxicity and inhibition of intercellular communication in cultured B6C3F1 mouse hepatocytes and human keratinocytes (NHEK cells). GTA (0.05-50 micrograms/ml) prevented the killing of hepatocytes (measured by lactate dehydrogenase release) by paraquat (1-10 mM) and glucose oxidase (0.8-40 micrograms/ml) in a concentration-dependent fashion. GTA (50 micrograms/ml) also prevented the inhibition of hepatocyte intercellular communication by paraquat (5 mM), glucose oxidase (0.8 micrograms/ml), and phenobarbital (500 micrograms/ml). In addition, GTA (50 micrograms/ml) prevented the inhibition of intercellular communication in human keratinocytes by TPA (100 ng/ml). Cytotoxicity and inhibition of intercellular communication, two possible mechanisms by which tumor promoters may produce their promoting effects were therefore prevented by GTA. The inhibition of these two effects of pro-oxidant compounds may suggest a mechanism by which GTA inhibits tumor promotion in vivo.

291. Mutat Res 1989 Jan;210(1):1-8

Crude tea extracts decrease the mutagenic activity of N-methyl-N'-nitro-N-nitrosoguanidine in vitro and in intragastric tract of rats.

Jain AK, Shimoi K, Nakamura Y, Kada T, Hara Y, Tomita I

Laboratory of Health Science, School of Pharmaceutical Sciences, University of Shizuoka, Japan.

The effects of tea extracts and their ingredients, catechins and L-ascorbic acid (AsA), on the mutagenicity of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were examined in vitro and in the stomachs of rats using E. coli WP2 and S. typhimurium TA100. The extracts of green tea and black tea leaves decreased the mutagenic activity of MNNG to E. coli WP2 in vitro in a desmutagenic manner. Catechins such as (-)-epigallocatechin from green tea leaves and the low-molecular-weight tannin fraction isolated from black tea extract with HP-20 resin also exhibited inhibitory effects against the mutagenic activity of MNNG. A desmutagenic effect of AsA on MNNG-induced mutagenicity was observed depending on the dose, though it was complicated. The effects were also demonstrated in the stomachs of rats by assaying the bacterial mutagenic in vitro; the tea extracts previously given orally to rats reduced the mutagenic activity of MNNG remarkably, though simultaneous administration showed less effect. The effectiveness of tea extracts for the decrease of MNNG-induced mutagenesis in vitro and in vivo suggests that the habitual drinking of tea may reduce the tumor-initiating potency of MNNG-type nitrosoureido compounds if they are formed in the stomach.

292. J Nutr Sci Vitaminol (Tokyo) 1986 Dec;32(6):613-22

Effect of green tea catechins on plasma cholesterol level in cholesterol-fed rats.

Muramatsu K, Fukuyo M, Hara Y

Effects of tea catechins (tannins) on lipid metabolism were studied in male weanling rats fed a 25% casein diet containing 15% lard and 1% cholesterol for 28 days. Crude tea catechins prepared from green tea powder were supplemented at a 1% and 2% of the lard-cholesterol diet. The addition of 2% tea catechins slightly depressed growth but at the 1% level was without effect. Tea catechins decreased plasma total cholesterol, cholesterol ester, total cholesterol--HDL-cholesterol (VIDL-+LDL-cholesterol) and atherogenic index (VLDL-+LDL-cholesterol/HDL-cholesterol). Hematocrit and plasma glucose were not altered by the addition of tea catechins. The liver weight, liver total lipids and cholesterol concentrations in rats fed the lard-cholesterol diet increased more than in the control rats, but the addition of tea catechins to the lard-cholesterol diet decreased those parameters. Tea catechin supplementation increased fecal excretion of total lipids and cholesterol. The results demonstrate that tea catechins exert a hypocholesterolemic effect in cholesterol-fed rats.