Antioxidant chemistry of green tea catechins: Oxidation products of (-)-epigallocatechin gallate and (-)-epigallocatechin with peroxidase

Tea catechins display possible antitumor activities which are believed to b e mainly due to their antioxidative effects. However, the specific mechanis ms of the antioxidant action of tea catechins remain unclear. In this study , (-)-epigallocatechin gallate (EGCG) and (-)-epigallocatechin (EGC) were r eacted with peroxidase in the presence of H2O2 to produce two oxidation pro ducts. These two products were determined as the symmetric dimer of EGCG an d EGG, respectively. Thus, the trihydroxyphenyl B-ring, rather than galloyl moiety, was the more active site of antioxidant reaction. Moreover, this s tudy provided some insight into the specific mechanism of antioxidant react ions of tea catechins, and a possible mechanism is proposed.