Identification of metabolites of (-)-epicatechin gallate and their metabolic fate in the rat.

After intravenous administration of (−)-epicatechin gallate to Wistar male rats, its biliary metabolites were examined. Deconjugated forms of (−)-epicatechin gallate metabolites were prepared by β-glucuronidase/sulfatase treatment and purified by HPLC. Five compounds were subjected to FAB-MS and NMR analyses. These metabolites were shown to be (−)-epicatechin gallate, 3‘-O-methyl-(−)-epicatechin gallate, 4‘-O-methyl-(−)-epicatechin gallate, 4‘ ‘-O-methyl-(−)-epicatechin gallate, and 3‘,4‘ ‘-di-O-methyl-(−)-epicatechin gallate. After oral administration, five major metabolites excreted in rat urine were purified in their deconjugated forms and their chemical structures identified. They were degradation products from (−)-epicatechin gallate, pyrogallol, 5-(3,4-dihydroxyphenyl)-γ-valerolactone, 4-hydroxy-5-(3,4-dihydroxyphenyl)valeric acid, 3-(3-hydroxyphenyl)propionic acid, and m-coumaric acid. Time course analysis of the identified (−)-epicatechin gallate metabolites showed that (−)-epicatechin gallate and...