Epicatechin and catechin are O-methylated and glucuronidated in the small intestine

There is considerable interest in the bioavailability of polyphenols and their bioactivity in vivo. We have studied the absorption and metabolism of catechin and epicatechin in the small intestine and the comparative transfer across the jejunum and ileum, Perfusion of isolated jejunum with the flavanols resulted in glucuronidation (similar to 45%), O-methylation: 3'-O-Methyl- and 4'-O-methyl- (similar to 30%), and O-methyl-glucuronidation (similar to 20% of total flavanols identified) during transfer across the enterocytes to the serosal side, This demonstrates the activity of catechol-O-methyl transferases in the metabolism of flavanols and suggests that these metabolites and conjugates are likely to enter the portal vein. In contrast, in the case of the ileum, the majority of the flavanols appeared on the serosal side unmetabolised and the total percentage of flavanols transferred was higher than that in the jejunum (similar to fivefold). (C) 2000 Academic Press.