Characterization of the oxidation products of (-)-epigallocatechin gallate,a bioactive tea polyphenol,on incubation in neutral solution

摘要

(-)-Epigallocatechin gallate (EGCG) (1) changqs rapidly into various products in neutral solution containing trace amounts of metal ions as catalysts.In addition to theasinensins A (2) and D (3),(-)-gallocatechin gallate (4),and gallic acid,five products were isolated from a reaction mixture resulting from the incubation of 1.MS and NMR spectroscopic analyses of the products revealed two monomeric [EGCG-MOx-Ml (5) and M2 (6)],and three dimeric [EGCG-MOx-Dl (7),D2 (8) and D3 (9)] structures.