Catabolism of (+)-catechin and (-)-epicatechin by rat intestinal microbiota

Catabolism of (+)-catechin (+C) and (-)-epicatechin (EC) by rat intestinal microbiota was examined in vitro. +C and EC metabolites isolated were identified by LC-MS and NMR analyses. As a result, 4-hydroxy-5-(3-hydroxyphenyl)valeric acid (C-5 and EC-5), 4-oxo-5-(3,4-dihydorxyphenyl)valeric acid (EC-7), 4-oxo-5-(3-hydorxyphenyl)valeric acid (EC-8), and 1-(4-hydroxyphenyl)-3-(2,4,6-trihydroxyphenyl)propan-2-ol (EC-13) were identified as new metabolites of +C or EC. From the measurement of optical rotation, each of the +C and EC metabolites possessing the same chemical structure and chiral carbon was inferred to have an enantiomeric relationship to each other and to maintain the configurations at the 3-position of the original catechins. On the basis of these findings together with previous information, the proposed metabolic pathway of +C and EC by rat intestinal microbiota was updated.