Chemical studies of the antioxidant mechanism of theaflavins:: radical reaction products of theaflavin 3,3′-digallate with hydrogen peroxide

The objective of the current study is to characterize the reaction products of theaflavin 3,3'-digallate, one of the major characteristic polyphenols of black tea, with hydroxyl radicals generated by hydrogen peroxide, with the aim of gaining insights into specific mechanisms of antioxidant reactions in physiological systems. Two major reaction products were isolated and identified using high-field 1D and 2D NMR spectral analysis. Both of them are A-ring fission products. The observation of these compounds indicates that the A ring rather than the benzotropolone moiety is the initial site for formation of reaction products in the hydrogen peroxide oxidant system. (C) 2003 Elsevier Ltd. All rights reserved.