Three New Oxidation Products Produced from Epigallocatechin-3- O -gallate and Epicatechin-3- O -gallate

Abstract

During chemical studies on uncharacterized black tea polyphenols, the enzymatic oxidation of a mixture of epigallocatechin-3-O-gallate (1) and epicatechin-3-O-gallate (2) was examined, and three new dimeric products together with six known catechin dimers were isolated. Two of the new compounds have tricyclo[5.2.2.0^2,6]undecane and tricyclo[5.2.1.0^2,6]decane carboxyl structures generated by oxidative coupling between two pyrogallol-B-rings of 1. Another new product was a dimer connected by a C-C bond between the B-ring of 1 and a galloyl group of 2.

Keywords

Black tea Catechin Oxidation Thearubigins Polyphenol

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