Green tea flavonoids

YOSHiNORi s, MASATOSHi T and HiSASHi I (1987) Breath deodorant chewing gum containing green tea flavonoids , Shokuhin Kogyo, 30 (24), 43-51. 

Schamberger, G.P. and Labuza, T.P. Effect of green tea flavonoids on MaiUard browning in UHT milk, Lebensm-Wiss-u-Technol., 40, 1410, 2007. 

The total antioxidant activity of teas and tea polyphenols in aqueous phase oxidation reactions has been deterrnined using an assay based on oxidation of 2,2 -azinobis-(3-ethylbenzothiazoline-sulfonate) (ABTS) by peroxyl radicals (114—117). Black and green tea extracts (2500 ppm) were found to be 8—12 times more effective antioxidants than a 1-mAf solution of the water-soluble form of vitamin E, Trolox. The most potent antioxidants of the tea flavonoids were found to be epicatechin gallate and epigallocatechin gallate. A 1-mAf solution of these flavanols were found respectively to be 4.9 and 4.8 times more potent than a 1-mAf solution of Trolox in scavenging an ABT radical cation. 

YOUNG J F, DRAGSTED L O, HARALDSDOTTIR J, DANESHVAR B, KALL M A, LOFT S, NILSSON L, NIELSEN S E, MAYER B, SKIBSTED L H, HUYNH-BA T, HERMETTER A and SANDSTROM B (2002) Green tea extract only affects markers of oxidative status postprandially lasting antioxidant effect of flavonoid-free diet, Brit J Nutr, 87, 343-55. 

Many flavonoids have antioxidant properties and as such are thought to protect humans against cardiovascular disease and cancer. Foods containing flavonoids (e.g., green tea, soy, and red wine) are touted as beneficial for health. 

Flavonoids are found in fruits, vegetables, seeds, and flowers, as well as in some drinks, such as beer, wine, black and green teas, and soy beverages. Consequently, these kind of compounds are consumed in a normal diet, although they can also be consumed as supplements. 

The effects of flavonoids derived from soybean, cocoa, wine, and green tea on the reduction of risk for chronic cardiovascular diseases have been studied the most. 

Iron-, copper-, and zinc complexes of rutin, dihydroquercetin, and green tea epicatechins were found to be much more efficient inhibitors than parent flavonoids of toxic effects of chrysotile asbestos fibers on peritoneal macrophages and erythrocytes [168], It was proposed that in this case the enhanced activity of metal-flavonoid complexes was increased by the absorption on chrysotile fibers. 

Another isocratic elution method was applied for the determination of flavonols in green and black tea leaves and green tea infusions by RP-HPLC. The chemical structures of the flavonols studied are shown in Fig. 2.66. Infusions of teas were prepared by mixing lg of tea leaves with 100 ml of boiling water for 5min, then they have filtered and used for HPLC analysis. The infusion step was repeated three times. Flavonoids were hydrolysed by mixing lg of tea leaves with 40 ml of 60 per cent aqueous ethanol and 5 ml of 6 M HC1. The suspension was heated at 95°C for 2 h, then filtered and the volume was adjusted to 50 ml with 60 per cent aqueous ethanol. Separation was performed in an ODS column (150 X 4.6mm i.d.) operated at 30°C. The isocratic mobile phase consisted of 30 per cent aqueous ACN in 0.025 M KH2P04, and the pH was adjusted to 2.5 with 6 M HC1. The... 

Wada, S. et al., Glycosidic flavonoids as rat-liver injury preventing compounds from green tea, Biosci. Biotechnol. Biochem., 64, 2262, 2000. 

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