Acid mediated hydrolysis of blueberry anthocyanins.
Ichiyanagi T, Oikawa K, Tateyama C, Konishi T Department of Hygiene Chemistry, Niigata College of Pharmacy, Japan. email@example.com
Chem Pharm Bull (Tokyo) 2001 Jan;49(1):114-7
Acid mediated hydrolysis of anthocyanins was studied using capillary zone electrophoresis (CZE). A commercially available wild blueberry (Bilberry) extract was dissolved in different concentrations of TFA (0.1, 1, 3, 9%), then was subjected to thermodecomposition reaction at 95 degrees C. After the reaction, the samples were analyzed by CZE. The hydrolysis rate of each anthocyanin and the formation of the aglycon were determined by the change in the peak pattern of the anthocyanins in the electropherogram. Each anthocyanin peak decreased time dependently in a first order kinetic fashion. It was revealed that the hydrolysis rate of each anthocyanin was determined primarily by the type of conjugated sugar and not by the aglycon structure. The rate constant of anthocyanin hydrolysis was in the following order, arabinoside>galactoside>glucoside without regard to the aglycon structure. The kinetic behavior of this anthocyanin hydrolysis together with the CZE mobility allowed us to identify an unknown CZE peak as delphinidin 3-O-beta-arabinoside. At low TFA concentration, significant decomposition of the anthocyanidin nucleus occurred, but the glycoside hydrolysis predominated at high TFA concentration. It was further revealed that the aglycon released reacted successively to form polymeric products at higher TFA conditions.
Comparison of anthocyanin distribution in different blueberry sources by capillary zone electrophoresis.
Ichiyanagi T, Tateyama C, Oikawa K, Konishi T Department of Hygiene Chemistry, Niigata College of Pharmacy, Japan.
Biol Pharm Bull 2000 Apr;23(4):492-7
Capillary zone electrophoretic separation of blueberry anthocyanins was studied using a Na-borate buffer containing trans-1,2-diaminocyclohexane-N,N,N',N'-tetra acetic acid monohydrate (CyDTA) as the carrier buffer. The separation conditions were precisely examined using an aqueous extract of bilberry (wild type blueberry) as the separation sample which is rich in this type and amount of anthocyanins. Each separated peak was identified by comparing the mobility with that of anthocyanin standards after normalization against the mobility of malvidin 3-o-glucoside (Mv 3-Glc) added as an internal standard. As salt concentrations of the running buffer increased, the peak resolution was markedly improved over the whole range of separation, especially, among the fast moving components (petunidin 3-glucoside, cyanidin 3-glucoside and malvidin 3-galactoside). Inversely, the peak separation both between petunidin 3-glucoside and peonidin 3-glucoside, and between delphinidin 3-glucoside and petunidin 3-galactoside, respectively, were decreased. The anthocyanins were, however, successfully separated by decreasing the buffer pH. Good separation of anthocyanins was finally achieved by 30 mM Na-borate (pH 8.78) containing 7.5 mM CyDTA within 10 min. Under this separation condition, anthocyanins from different blueberry sources were analyzed. The results revealed that different blueberry sources had their own patterns of anthocyanin distribution and amounts in the extracts, thus the present method is suitable for the quality control of anthocyanin-containing food materials.
In vitro anticancer activity of fruit extracts from Vaccinium species.
Bomser J, Madhavi DL, Singletary K, Smith MA Department of Food Science and Human Nutrition, University of Illinois, Urbana 61801, USA.
Planta Med 1996 Jun;62(3):212-6
Fruit extracts of four Vaccinium species (lowbush blueberry, bilberry, cranberry, and lingonberry) were screened for anticarcinogenic compounds by a combination of fractionation and in vitro testing of their ability to induce the Phase II xenobiotic detoxification enzyme quinone reductase (QR) and to inhibit the induction of ornithine decarboxylase (ODC), the rate-limiting enzyme in polyamine synthesis, by the tumor promoter phorbol 12-myristate 13-acetate (TPA). The crude extracts, anthocyanin and proanthocyanidin fractions were not highly active in QR induction whereas the ethyl acetate extracts were active QR inducers. The concentrations required to double QR activity (designated CDqr) for the ethyl acetate extracts of lowbush blueberry, cranberry, lingonberry, and bilberry were 4.2, 3.7, 1.3, and 1.0 microgram tannic acid equivalents (TAE), respectively, Further fractionation of the bilberry ethyl acetate extract revealed that the majority of inducer potency was contained in a hexane/chloroform subfraction (CDqr = 0.07 microgram TAE). In contrast to their effects on QR, crude extracts of lowbush blueberry, cranberry, and lingonberry were active inhibitors of ODC activity. The concentrations of these crude extracts needed to inhibit ODC activity by 50% (designated IC50) were 8.0, 7.0, and 9.0 micrograms TAE, respectively. The greatest activity in these extracts appeared to be contained in the polymeric proanthocyanidin fractions of the lowbush blueberry, cranberry, and lingonberry fruits (IC50 = 3.0, 6.0, and 5.0 micrograms TAE, respectively). The anthocyanidin and ethyl acetate extracts of the four Vaccinium species were either inactive or relatively weak inhibitors of ODC activity. Thus, components of the hexane/chloroform fraction of bilberry and of the proanthocyanidin fraction of lowbush blueberry, cranberry, and lingonberry exhibit potential anticarcinogenic activity as evaluated by in vitro screening tests.