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Abstracts

Life Extension Magazine August 2011
Abstracts

Lipoic acid

Feeding acetyl-L-carnitine and lipoic acid to old rats significantly improves metabolic function while decreasing oxidative stress.

Mitochondrial-supported bioenergetics decline and oxidative stress increases during aging. To address whether the dietary addition of acetyl-l-carnitine [ALCAR, 1.5% (wt/vol) in the drinking water] and/or (R)-alpha-lipoic acid [LA, 0.5% (wt/wt) in the chow] improved these endpoints, young (2-4 mo) and old (24-28 mo) F344 rats were supplemented for up to 1 mo before death and hepatocyte isolation. ALCAR+LA partially reversed the age-related decline in average mitochondrial membrane potential and significantly increased (P = 0.02) hepatocellular O(2) consumption, indicating that mitochondrial-supported cellular metabolism was markedly improved by this feeding regimen. ALCAR+LA also increased ambulatory activity in both young and old rats; moreover, the improvement was significantly greater (P = 0.03) in old versus young animals and also greater when compared with old rats fed ALCAR or LA alone. To determine whether ALCAR+LA also affected indices of oxidative stress, ascorbic acid and markers of lipid peroxidation (malondialdehyde) were monitored. The hepatocellular ascorbate level markedly declined with age (P = 0.003) but was restored to the level seen in young rats when ALCAR+LA was given. The level of malondialdehyde, which was significantly higher (P = 0.0001) in old versus young rats, also declined after ALCAR+LA supplementation and was not significantly different from that of young unsupplemented rats. Feeding ALCAR in combination with LA increased metabolism and lowered oxidative stress more than either compound alone.

Proc Natl Acad Sci U S A. 2002 Feb 19;99(4):1870-5

Lipoic acid as an anti-inflammatory and neuroprotective treatment for Alzheimer’s disease.

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder that destroys patient memory and cognition, communication ability with the social environment and the ability to carry out daily activities. Despite extensive research into the pathogenesis of AD, a neuroprotective treatment - particularly for the early stages of disease - remains unavailable for clinical use. In this review, we advance the suggestion that lipoic acid (LA) may fulfil this therapeutic need. A naturally occurring cofactor for the mitochondrial enzymes pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase, LA has been shown to have a variety of properties which can interfere with the pathogenesis or progression of AD. For example, LA increases acetylcholine (ACh) production by activation of choline acetyltransferase and increases glucose uptake, thus supplying more acetyl-CoA for the production of ACh. LA chelates redox-active transition metals, thus inhibiting the formation of hydroxyl radicals and also scavenges reactive oxygen species (ROS), thereby increasing the levels of reduced glutathione. In addition, LA down-regulates the expression of redox-sensitive pro-inflammatory proteins including TNF and inducible nitric oxide synthase. Furthermore, LA can scavenge lipid peroxidation products such as hydroxynonenal and acrolein. In human plasma, LA exists in an equilibrium of free and plasma protein bound form. Up to 150 muM, it is bound completely, most likely binding to high affinity fatty acid sites on human serum albumin, suggesting that one large dose rather than continuous low doses (as provided by “slow release” LA) will be beneficial for delivery of LA to the brain. Evidence for a clinical benefit for LA in dementia is yet limited. There are only two published studies, in which 600 mg LA was given daily to 43 patients with AD (receiving a standard treatment with choline-esterase inhibitors) in an open-label study over an observation period of up to 48 months. Whereas the improvement in patients with moderate dementia was not significant, the disease progressed extremely slowly (change in ADAScog: 1.2 points=year, MMSE: -0.6 points=year) in patients with mild dementia (ADAScog<15). Data from cell culture and animal models suggest that LA could be combined with nutraceuticals such as curcumin, (-)-epigallocatechin gallate (from green tea) and docosahexaenoic acid (from fish oil) to synergistically decrease oxidative stress, inflammation, Abeta levels and Abeta plaque load and thus provide a combined benefit in the treatment of AD.

Adv Drug Deliv Rev. 2008 Oct-Nov;60(13-14): 1463-70

Lipoic acid: a novel therapeutic approach for multiple sclerosis and other chronic inflammatory diseases of the CNS.

The naturally occurring antioxidant lipoic acid (LA) was first described as an essential cofactor for the conversion of pyruvate to Acetyl-CoA, a critical step in respiration. LA is now recognized as a compound that has many biological functions. Along with its reduced form dihydrolipoic acid (DHLA), LA reduces and recycles cellular antioxidants such as glutathione, and chelates zinc, copper and other transition metal ions in addition to heavy metals. LA can also act as a scavenger of reactive oxygen and nitrogen species. By acting as an insulin mimetic agent, LA stimulates glucose uptake in many different cell types and can also modulate insulin signaling. The p38 and ERK MAP kinase pathways, AKT and NFkappaB are all regulated by LA. In addition, LA activates the prostaglandin EP2 and EP4 receptors to stimulate the production of the small molecule cyclic adenosine 5’ monophosphate (cAMP). These diverse actions suggest that LA may be therapeutically effective in treating oxidative stress associated diseases. This review discusses the known biochemical properties of LA, its antioxidant properties, its ability to modulate signal transduction pathways, and the recent progress made in the utilization of LA as a therapeutic alternative for multiple sclerosis, Alzheimer’s disease and diabetic neuropathy.

Endocr Metab Immune Disord Drug Targets. 2008 Jun;8(2):132-42

Prevention of mutation, cancer, and other age-associated diseases by optimizing micronutrient intake.

I review three of our research efforts which suggest that optimizing micronutrient intake will in turn optimize metabolism, resulting in decreased DNA damage and less cancer as well as other degenerative diseases of aging. (1) Research on delay of the mitochondrial decay of aging, including release of mutagenic oxidants, by supplementing rats with lipoic acid and acetyl carnitine. (2) The triage theory, which posits that modest micronutrient deficiencies (common in much of the population) accelerate molecular aging, including DNA damage, mitochondrial decay, and supportive evidence for the theory, including an in-depth analysis of vitamin K that suggests the importance of achieving optimal micronutrient intake for longevity. (3) The finding that decreased enzyme binding constants (increased Km) for coenzymes (or substrates) can result from protein deformation and loss of function due to an age-related decline in membrane fluidity, or to polymorphisms or mutation. The loss of enzyme function can be compensated by a high dietary intake of any of the B vitamins, which increases the level of the vitamin-derived coenzyme. This dietary remediation illustrates the importance of understanding the effects of age and polymorphisms on optimal micronutrient requirements. Optimizing micronutrient intake could have a major effect on the prevention of cancer and other degenerative diseases of aging.

J Nucleic Acids. 2010 Sep 22;2010

The effects and mechanisms of mitochondrial nutrient alpha-lipoic acid on improving age-associated mitochondrial and cognitive dysfunction: an overview.

We have identified a group of nutrients that can directly or indirectly protect mitochondria from oxidative damage and improve mitochondrial function and named them “mitochondrial nutrients”. The direct protection includes preventing the generation of oxidants, scavenging free radicals or inhibiting oxidant reactivity, and elevating cofactors of defective mitochondrial enzymes with increased Michaelis-Menten constant to stimulate enzyme activity, and also protect enzymes from further oxidation, and the indirect protection includes repairing oxidative damage by enhancing antioxidant defense systems either through activation of phase 2 enzymes or through increase in mitochondrial biogenesis. In this review, we take alpha-lipoic acid (LA) as an example of mitochondrial nutrients by summarizing the protective effects and possible mechanisms of LA and its derivatives on age-associated cognitive and mitochondrial dysfunction of the brain. LA and its derivatives improve the age-associated decline of memory, improve mitochondrial structure and function, inhibit the age-associated increase of oxidative damage, elevate the levels of antioxidants, and restore the activity of key enzymes. In addition, co-administration of LA with other mitochondrial nutrients, such as acetyl-L: -carnitine and coenzyme Q10, appears more effective in improving cognitive dysfunction and reducing oxidative mitochondrial dysfunction. Therefore, administrating mitochondrial nutrients, such as LA and its derivatives in combination with other mitochondrial nutrients to aged people and patients suffering from neurodegenerative diseases, may be an effective strategy for improving mitochondrial and cognitive dysfunction.

Neurochem Res. 2008 Jan;33(1):194-203

Alpha-Lipoic acid increases energy expenditure by enhancing adenosine monophosphate-activated protein kinase-peroxisome proliferator-activated receptor-gamma coactivator-1alpha signaling in the skeletal muscle of aged mice.

Skeletal muscle mitochondrial dysfunction is associated with aging and diabetes, which decreases respiratory capacity and increases reactive oxygen species. Lipoic acid (LA) possesses antioxidative and antidiabetic properties. Metabolic action of LA is mediated by activation of adenosine monophosphate-activated protein kinase (AMPK), a cellular energy sensor that can regulate peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha), a master regulator of mitochondrial biogenesis. We hypothesized that LA improves energy metabolism and mitochondrial biogenesis by enhancing AMPK-PGC-1alpha signaling in the skeletal muscle of aged mice. C57BL/6 mice (24 months old, male) were supplemented with or without alpha-LA (0.75% in drinking water) for 1 month. In addition, metabolic action and cellular signaling of LA were studied in cultured mouse myoblastoma C2C12 cells. Lipoic acid supplementation improved body composition, glucose tolerance, and energy expenditure in the aged mice. Lipoic acid increased skeletal muscle mitochondrial biogenesis with increased phosphorylation of AMPK and messenger RNA expression of PGC-1alpha and glucose transporter-4. Besides body fat mass, LA decreased lean mass and attenuated phosphorylation of mammalian target of rapamycin (mTOR) signaling in the skeletal muscle. In cultured C2C12 cells, LA increased glucose uptake and palmitate beta-oxidation, but decreased protein synthesis, which was associated with increased phosphorylation of AMPK and expression of PGC-1alpha and glucose transporter-4, and attenuated phosphorylation of mTOR and p70S6 kinase. We conclude that LA improves skeletal muscle energy metabolism in the aged mouse possibly through enhancing AMPK-PGC-1alpha-mediated mitochondrial biogenesis and function. Moreover, LA increases lean mass loss possibly by suppressing protein synthesis in the skeletal muscle by down-regulating the mTOR signaling pathway. Thus, LA may be a promising supplement for treatment of obesity and/or insulin resistance in older patients.

Metabolism. 2010 Jul;59(7):967-76

Alpha-lipoic acid reduces expression of vascular cell adhesion molecule-1 and endothelial adhesion of human monocytes after stimulation with advanced glycation end products.

Advanced glycation end products (AGEs) have been identified as relevant mediators of late diabetic complications such as atherosclerotic disease. The endothelial migration of monocytes is one of the first steps in atherogenesis and monocyte-endothelial interaction itself is linked to the expression of adhesion molecules like vascular cell adhesion molecule-1 (VCAM-1). Recently, stimulation of VCAM-1 by AGEs has been demonstrated. Since endothelial stimulation by AGEs is followed by generation of oxygen free radicals with subsequent activation of nuclear transcription factor kappaB, we investigated the influence of alpha-lipoic acid on the expression of VCAM-1 and monocyte adherence to endothelial cells in vitro by means of cell-associated chemiluminescence assays and quantitative reverse transcriptase polymerase chain reaction using a constructed recombinant RNA standard. We found that alpha-lipoic acid was able to decrease the number of VCAM-1 transcripts from 41. 0+/-11.2 to 9.5+/-4.7 RNA copies per cell in AGE-stimulated cell cultures. Furthermore, expression of VCAM-1 was suppressed in a time- and dose-dependent manner by alpha-lipoic acid as shown by chemiluminescence endothelial cell assay. Pretreatment of endothelial cells with 0.5 mM or 5 mM alpha-lipoic acid reduced AGE-induced endothelial binding of monocytes from 22.5+/-2.9% to 18. 3+/-1.9% and 13.8+/-1.8% respectively. Thus, we suggest that extracellularly administered alpha-lipoic acid reduces AGE-albumin-induced endothelial expression of VCAM-1 and monocyte binding to endothelium in vitro. These in vitro results may contribute to the understanding of a potential antioxidative treatment of atherosclerosis.

Clin Sci (Lond). 1999 Jan;96(1):75-82

Lipoic acid prevents hypertension, hyperglycemia, and the increase in heart mitochondrial superoxide production.

BACKGROUND: The present study was designed to investigate whether the effects of dietary supplementation with alpha-lipoic acid could prevent the increase in mitochondrial superoxide production in the heart as well as the enhanced formation of advanced glycation end-products (AGE) that are associated with the development of hypertension and insulin resistance in chronically glucose-fed rats. METHODS: Sprague Dawley rats were either given or not given a 10% D-glucose solution to drink during 4 weeks, combined either with a normal chow diet or with alpha-lipoic acid supplemented diet. The oxidative stress was evaluated by measuring the heart mitochondrial superoxide production using the lucigenin chemiluminescence method. The formation of AGE was also assessed in plasma and aorta. RESULTS: Chronic administration of glucose resulted in a 29% increase in blood pressure, 30% increase in glycemia, 286% increase in insulinemia, and 408% increase in insulin resistance index. Chronic glucose feeding also resulted in a 22% greater mitochondrial superoxide anion production in heart and in an increase of 63% in AGE content in aorta. Increases in blood pressure, aorta AGE content and heart mitochondrial superoxide production were prevented in the rats fed glucose supplemented with lipoic acid. The simultaneous treatment with lipoic acid also attenuated the rise in insulin levels as well as in insulin resistance in the glucose fed rats. CONCLUSIONS: These findings demonstrate that alpha-lipoic acid supplementation prevents development of hypertension and hyperglycemia, presumably through its antioxidative properties, as reflected by prevention of an increase in heart mitochondrial superoxide anion production and in AGE formation in the aorta of chronically glucose treated rats.

Am J Hypertens. 2003 Mar;16(3):173-9

Lipoic acid improves glucose utilisation and prevents protein glycation and AGE formation.

The present study investigates the antiglycating effect of alpha-lipoic acid (LA) in high fructose-fed rats in vivo and its potential to inhibit the process of glycation in vitro. In addition, the effect of LA on glucose utilisation in rat diaphragm was also studied. Rats fed a high fructose diet (60% total calories) were administered with 35 mg/kg b.w, lipoic acid (LA) intraperitoneally for 20 days. The effects of LA on plasma glucose, fructosamine, protein glycation and glycated haemoglobin in high fructose rats and on in vitro glycation were studied. In vitro utilization of glucose was carried out in normal rat diaphragm in the presence and absence of insulin in which LA was used as an additive. The contents of glucose, glycated protein, glycated haemoglobin and fructosamine were significantly lowered on LA administration to high fructose-fed rats. LA prevented in vitro glycation and the accumulation of advanced glycation end products. Further LA enhanced glucose utilization in the rat diaphragm. This effect was additive to that of insulin and did not interfere with the action of insulin. The findings provide evidence for the therapeutic utility of lipoic acid in diabetes and its complications.

Pharmazie. 2005 Oct;60(10):772-5

Alpha-lipoic acid as a dietary supplement: molecular mechanisms and therapeutic potential.

Alpha-lipoic acid (LA) has become a common ingredient in multivitamin formulas, anti-aging supplements, and even pet food. It is well-defined as a therapy for preventing diabetic polyneuropathies, and scavenges free radicals, chelates metals, and restores intracellular glutathione levels which otherwise decline with age. How do the biochemical properties of LA relate to its biological effects? Herein, we review the molecular mechanisms of LA discovered using cell and animal models, and the effects of LA on human subjects. Though LA has long been touted as an antioxidant, it has also been shown to improve glucose and ascorbate handling, increase eNOS activity, activate Phase II detoxification via the transcription factor Nrf2, and lower expression of MMP-9 and VCAM-1 through repression of NF-kappa B. LA and its reduced form, dihydrolipoic acid, may use their chemical properties as a redox couple to alter protein conformations by forming mixed disulfides. Beneficial effects are achieved with low micromolar levels of LA, suggesting that some of its therapeutic potential extends beyond the strict definition of an antioxidant. Current trials are investigating whether these beneficial properties of LA make it an appropriate treatment not just for diabetes, but also for the prevention of vascular disease, hypertension, and inflammation.

Biochim Biophys Acta. 2009 Oct;1790(10):1149-60

Vascular oxidative stress and inflammation increase with age: ameliorating effects of alpha-lipoic acid supplementation.

Increased oxidative stress and inflammation causally contribute to cardiovascular diseases, for which advanced age is a major risk factor. We found that indicators of oxidative stress, including NADPH oxidase activity and superoxide levels, were significantly increased in aortas of old (22-24 months) versus young (3-4 months) male F344 rats, whereas superoxide dismutase (SOD) activity was decreased. Aortic mRNA and protein levels of NOX4, the principal catalytic subunit of NADPH oxidase in vascular cells, also were increased with age, but not NOX2 and p22(phox). Indicators of inflammation, including activation of NFkappaB and upregulation of vascular cell adhesion molecule-1 (VCAM-1) in aorta, and monocyte chemotactic protein-1 (MCP-1) in plasma, also were significantly increased in old rats. Supplementation with 0.2% (wt/wt) (R)-alpha-lipoic acid (LA) for 2 weeks caused a nonsignificant decrease in NADPH oxidase activity in aged aorta and a significant decrease in mRNA--but not protein--levels of NOX4 and VCAM-1. Furthermore, LA reversed the age-dependent changes in aortic SOD activity and plasma MCP-1 levels. Hence, vascular oxidative stress and inflammation increase with age and are ameliorated by LA supplementation.

Ann N Y Acad Sci. 2010 Aug;1203:151-9

Multifunctional lipoic acid conjugates.

Several hundreds of studies published the last decade have reported that alpha-lipoic acid (LA) possess the potential to intervene in various therapeutically interesting pathways. However, it should be noted that LA reportedly exerts most of its effects at high micromolar concentrations; that amides of LA exhibit higher biological activity than the parent compound; and that molecular combinations (hybrids) obtained by coupling LA with an amino-substituted bioactive moiety, possess multifunctional activity. The design and synthesis of hybrid molecules encompassing two pharmacophores in one molecular scaffold is a well established approach to the synthesis of more potent drugs with dual activity. Using this approach, various research groups have recently designed and synthesized hybrid compounds with antioxidant activity hyphenated with a wide variety of other activities such as neuroprotective, cardioprotective, anti-inflammatory, antidiabetic and anticancer activity as well as enzyme inhibition. Moreover, LA represents an ideal chemical entity for the development of biologically interesting functionalized nanoparticles. Many recent publications describe the use of LA: i) as component of nanospheres and nanoprodrugs, ii) as a linker for the attachment of lipids, carbohydrates, proteins and oligonucleotides on gold nanoparticles to form Self Assembled Monolayers (SAMs) and iii) as surface ligand for cap exchange reactions to prepare water-soluble semiconducting nanocrystal Quantum Dots (QDs). This review is focused on the growing field of the design and synthesis of LA conjugates, for the development of novel molecules with a dual mode of action and the construction of nanosized antioxidants, Self Assembled Monolayers and Quantum Dots.

Curr Med Chem. 2009;16(35):4728-42

Differential activity of lipoic acid enantiomers in cell culture.

It is unclear whether the two enantiomeric forms (R & S) of lipoic acid (LA) share similar pharmacological activity and the exact cellular targets of LA are not well identified. We oxidatively stressed 3 cell culture systems representing different cell types. Mitochondrial metabolism was the primary endpoint. When C6 glioma was damaged by hydrogen peroxide (H2O2), all forms of LA protected. Racemic and S-LA were less effective than the R-isomer that was also protective in tertiary butyl hydroperoxide (TBHP)-damaged C6 glioma. In PC12 cells, little damage was produced by TBHP; R-LA increased mitochondrial metabolism above the level of non-damaged control. In H2O2 damaged PC12 cells, R-LA and racemic LA (but not S-LA) not only protected against damage, but increased mitochondrial metabolism above the non-damaged control level. When BAE cells were damaged with H2O2, R- and racemic LA protected while S-LA was ineffective.

J Herb Pharmacother. 2005;5(3):43-54

Differential effects of lipoic acid stereoisomers on glucose metabolism in insulin-resistant skeletal muscle.

The racemic mixture of the antioxidant alpha-lipoic acid (ALA) enhances insulin-stimulated glucose metabolism in insulin-resistant humans and animals. We determined the individual effects of the pure R-(+) and S-(-) enantiomers of ALA on glucose metabolism in skeletal muscle of an animal model of insulin resistance, hyperinsulinemia, and dyslipidemia: the obese Zucker (fa/fa) rat. Obese rats were treated intraperitoneally acutely (100 mg/kg body wt for 1 h) or chronically [10 days with 30 mg/kg of R-(+)-ALA or 50 mg/kg of S-(-)-ALA]. Glucose transport [2-deoxyglucose (2-DG) uptake], glycogen synthesis, and glucose oxidation were determined in the epitrochlearis muscles in the absence or presence of insulin (13.3 nM). Acutely, R-(+)-ALA increased insulin-mediated 2-DG-uptake by 64% (P < 0.05), whereas S-(-)-ALA had no significant effect. Although chronic R-(+)-ALA treatment significantly reduced plasma insulin (17%) and free fatty acids (FFA; 35%) relative to vehicle-treated obese animals, S-(-)-ALA treatment further increased insulin (15%) and had no effect on FFA. Insulin-stimulated 2-DG uptake was increased by 65% by chronic R-(+)-ALA treatment, whereas S-(-)-ALA administration resulted in only a 29% improvement. Chronic R-(+)-ALA treatment elicited a 26% increase in insulin-stimulated glycogen synthesis and a 33% enhancement of insulin-stimulated glucose oxidation. No significant increase in these parameters was observed after S-(-)-ALA treatment. Glucose transporter (GLUT-4) protein was unchanged after chronic R-(+)-ALA treatment but was reduced to 81 +/- 6% of obese control with S-(-)-ALA treatment. Therefore, chronic parenteral treatment with the antioxidant ALA enhances insulin-stimulated glucose transport and non-oxidative and oxidative glucose metabolism in insulin-resistant rat skeletal muscle, with the R-(+) enantiomer being much more effective than the S-(-) enantiomer.

Am J Physiol. 1997 Jul;273(1 Pt 1):E185-91

Lipid lowering effect of antioxidant alpha-lipoic Acid in experimental atherosclerosis.

Accumulating data demonstrated that hypercholesterolemia and oxidative stress play an important role in the development of atherosclerosis. In the present study, a protective activity of alpha-lipoic acid; a metabolic antioxidant in hypercholesterolemic-induced animals was investigated. Eighteen adult male New Zealand White (NZW) rabbit were segregated into three groups labelled as group N, HCD and ALA (n = 6). Group N (normal control) was fed with normal chow, the rest (HCD and ALA) were fed with 100 g/head/day of 1% cholesterol rich diet to induce hypercholesterolemia. Four point two mg/body weight of alpha lipoic acid was concomintantly supplemented to the ALA group. Drinking water was given ad-libitum. The study was designed for 10 weeks. Blood sampling was taken from the ear lobe vein at the beginning, week 5 and week 10. Plasma was prepared for lipid profile estimation and microsomal lipid peroxidation index indicated with malondialdehyde (MDA) formation. At the end of the experiment, the animals were sacrificed and the aorta were excised for intimal lesion analysis. The plasma total cholesterol (TC) and low density lipoprotein (LDL) levels were found to be significantly low in ALA group compared to that of the HCD group (p<0.05). Similarly, low level of MDA (p<0.05) in ALA group was observed compared to that of the HCD group showing a significant reduction of lipid peroxidation activity. Histomorphometric intimal lesion analysis of the aorta showing less of atheromatous plaque formation in alpha lipoic acid supplemented group (p<0.05) compared to HCD group. These findings suggested that alpha lipoic acid posses a dual lipid lowering and anti-atherosclerotic properties indicated with low plasma TC and LDL levels and reduction of athero-lesion formation in hypercholesterolemic-induced rabbits.

J Clin Biochem Nutr. 2008 Sep;43(2):88-94

Alpha lipoic acid possess dual antioxidant and lipid lowering properties in atherosclerotic-induced New Zealand White rabbit.

There is accumulating data demonstrated hypercholesterolemia and oxidative stress play an important role in the development of atherosclerosis. In the present study, a protective activity of alpha-lipoic acid; a metabolic antioxidant in hypercholesterolemic-induced animals was investigated. Eighteen adult male New Zealand White (NZW) rabbit were segregated into three groups labelled as group K, AT and ALA (n=6). While group K was fed with normal chow and acted as a control, the rest fed with 100 g/head/day with 1% high cholesterol diet to induce hypercholesterolemia. 4.2 mg/body weight of alpha lipoic acid was supplemented daily to the ALA group. Drinking water was given ad-libitum. The study was designed for 10 weeks. Blood sampling was taken from the ear lobe vein at the beginning of the study, week 5 and week 10 and plasma was prepared for lipid profile estimation and microsomal lipid peroxidation index indicated with malondialdehyde (MDA) formation. Animals were sacrificed at the end of the study and the aortas were excised for intimal lesion analysis. The results showed a significant reduction of lipid peroxidation index indicated with low MDA level (p<0.05) in ALA group compared to that of the AT group. The blood total cholesterol (TCHOL) and low density lipoprotein (LDL) levels were found to be significantly low in ALA group compared to that of the AT group (p<0.05). Histomorphometric intimal lesion analysis of the aorta showing less of atheromatous plaque formation in alpha lipoic acid supplemented group (p<0.05) compared to that of AT group. These findings suggested that apart from its antioxidant activity, alpha lipoic acid may also posses a lipid lowering effect indicated with low plasma TCHOL and LDL levels and reduced the athero-lesion formation in rabbits fed a high cholesterol diet.

Biomed Pharmacother. 2008 Dec;62(10):716-22

Effect of combined treatment with alpha-Lipoic acid and acetyl-L-carnitine on vascular function and blood pressure in patients with coronary artery disease.

Mitochondria produce reactive oxygen species that may contribute to vascular dysfunction. alpha-Lipoic acid and acetyl-L-carnitine reduce oxidative stress and improve mitochondrial function. In a double-blind crossover study, the authors examined the effects of combined alpha-lipoic acid/acetyl-L-carnitine treatment and placebo (8 weeks per treatment) on vasodilator function and blood pressure in 36 subjects with coronary artery disease. Active treatment increased brachial artery diameter by 2.3% (P=.008), consistent with reduced arterial tone. Active treatment tended to decrease systolic blood pressure for the whole group (P=.07) and had a significant effect in the subgroup with blood pressure above the median (151+/-20 to 142+/-18 mm Hg; P=.03) and in the subgroup with the metabolic syndrome (139+/-21 to 130+/-18 mm Hg; P=.03). Thus, mitochondrial dysfunction may contribute to the regulation of blood pressure and vascular tone. Further studies are needed to confirm these findings and determine the clinical utility of alpha-lipoic acid/acetyl-L-carnitine as antihypertensive therapy.

J Clin Hypertens (Greenwich). 2007 Apr;9(4):249-55