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 (2
S)-1-(3,4-dihydroxyphenyl)-3-(2,4,6-trihydroxyphenyl)propan-2-ol (
1S) from −EC and −C, and (2
R)-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 (2
S)-1-(3-hydroxyphenyl)-3-(2,4,6-trihydroxyphenyl)propan-2-ol (
2S) and (2
R)-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.
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