The microbial metabolism of condensed (+)-catechins by rat-caecal microflora

Abstract

1. The metabolism of 2, 3-trans-3, 4-trans-3,5,7,3′)4′-pentahydroxy-4-(2,4,6-trihydroxyphenyl)-flavan and 2,3-trans-3, 4-trans-3,5,7,3′,4′,-pentahydroxy-4-(2,3-trans-3,5,7,3′,4′-pentahydroxyflavanyl-[8])-flavan in vitro by rat-caecal microflora was investigated.

2. Metabolites were extracted and enriched by column chromatography and preparative h.p.l.c., while structural determination was carried out using comparative g.l.c.-mass spectrometry and p.m.r. spectrometry.

3. The metabolites identified were derivatives of benzoic acid, phenylacetic acid, phenylpropionic acid and phenyllactic acid in addition to phloroglucinol, δ-(3-hydroxyphenyl)-7-valerolactone and 1-(3-hydroxyphenyl)-3-(2,4,6-trihydroxyphenyl)-propan-2-ol.

4. An additional metabolic route, which differs from the expected severance of the (+)-catechin-phloroglucinol bond and well-documented total heterocyclic ring degradation of flavanoids, is proposed.