Biotransformation of (-)-epicatechin 3-O-gallate by human intestinal bacteria

The biotransformation of (-)-epicatechin 3-O-gallate (1) and related compounds was undertaken using a human fecal suspension. Of fifteen metabolites isolated, four compounds were new, namely, two epimers of 1-(3'- hydroxyphenyl)-3-(2'',4'',6''-trihydroxyphenyl)propan-2-ols (6, 19); 2'',3''- dihydroxyphenoxyl 3-(3',4'-dihydroxyphenyl)propionate (14) and 1-(3',4'- dihydroxyphenyl)-3-(2'',4'',6''-trihydroxyphenyl)propan-2-ol (18). (-)- Epicatechin (2), (-)-epigallocatechin (16) and their 3-O-gallates (1, 17) were extensively metabolized by a human fecal suspension after incubation for 24 h, whereas the gallates (1, 17) resisted any degradation by a rat fecal suspension, even after a prolonged incubation time (48 h), suggesting a difference in metabolic ability between two intestinal bacterial mixtures from different species.