Bioconversion of (−)-Epicatechin, (+)-Epicatechin, (−)-Catechin, and (+)-Catechin by (−)-Epigallocatechin-Metabolizing Bacteria

Bioconversion of (-)-epicatechin (-EC), (+)-epicatechin (+EC), (-)-catechin (-C), and (+)-catechin (+C) by (-)-epigallocatechin (-EGC)-metabolizing bacteria, Adlercreutzia equolifaciens MT4s-5, Eggerthella lenta JCM 9979, and Flavonifractor plautii MT42, was investigated. A. equolifaciens MT4s-5 could catalyze C ring cleavage to form (2S)-1-(3,4-dihydroxyphenyl)-3-(2,4,6-trihydroxyphenyl)propan-2-ol (1S) from -EC and -C, and (2R)-1-(3,4-dihydroxyphenyl)-3-(2,4,6-trihydroxyphenyl)propan-2-ol (1R) from +C. The C ring cleavage by A. equolifaciens MT4s-5 was accelerated in the presence of hydrogen. E. lenta JCM 9979 also catalyzed C ring cleavage of -EC and +C to produce 1S and 1R, respectively. In the presence of hydrogen or formate, strain JCM 9979 showed not only stimulation of C ring cleavage but also subsequent 4'-dehydroxylation of 1S and 1R to produce (2S)-1-(3-hydroxyphenyl)-3-(2,4,6-trihydroxyphenyl)propan-2-ol (2S) and (2R)-1-(3-hydroxyphenyl)-3-(2,4,6-trihydroxyphenyl)propan-2-ol (2R), respectively. On the other hand, A. equolifaciens MT4s-5 did not show any 4'-dehydroxylation ability even in the presence of hydrogen. F. plautii MT42 could convert 1S, 1R, 2S, and 2R into their corresponding 4-hydroxy-5-hydroxyphenylvaleric acids and 5-hydroxyphenyl-γ-valerolactones simultaneously. Similar bioconversion was observed by F. plautii ATCC 29863 and F. plautii ATCC 49531.