Kim, Mihyang Kim, Su-Il Han, Jaehong Wang, Xiu-Ling Song, Dae-Geun Kim, Soo-Un 2024-01-20T21:31:17Z 2024-01-20T21:31:17Z 2021-09-03 2009-05-15 0099-2240 https://pubs.kist.re.kr/handle/201004/132488 Stereochemical course of isoflavanone dihydrodaidzein (DHD) reduction into the isoflavan (3S)-equol via tetrahydrodaidzein (THD) by the human intestinal anaerobic bacterium Eggerthella strain Julong 732 was studied. THD was synthesized by catalytic hydrogenation, and each stereoisomer was separated by chiral high-performance liquid chromatography. Circular dichroism spectroscopy was used to elucidate the absolute configurations of four synthetic THD stereoisomers. Rapid racemization of DHD catalyzed by Julong 732 prevented the substrate stereospecificity in the conversion of DHD into THD from being confirmed. The absolute configuration of THD, prepared by reduction of DHD in the cell-free incubation, was assigned as (3R, 4S) via comparison of the retention time to that of the authentic THD by chiral chromatography. Dehydroequol (DE) was unable to produce the (3S)-equol both in the cell-free reaction and in the bacterial transformation, negating the possible intermediacy of DE. Finally, the intermediate (3R,4S)-THD was reduced into (3S)-equol by the whole cell, indicating the inversion of stereochemistry at C-3 during the reduction. A possible mechanism accounting for the racemization of DHD and the inversion of configuration of THD during reduction into (3S)-equol is proposed. English AMER SOC MICROBIOLOGY EQUOL-PRODUCING BACTERIUM HUMAN FECES ISOFLAVONE METABOLITES ABSOLUTE-CONFIGURATIONS ANAEROBIC BACTERIUM SOY ISOFLAVONES DAIDZEIN IDENTIFICATION GENISTEIN DIHYDROGENISTEIN Stereospecific Biotransformation of Dihydrodaidzein into (3S)-Equol by the Human Intestinal Bacterium Eggerthella Strain Julong 732 Article 10.1128/AEM.02058-08 1 APPLIED AND ENVIRONMENTAL MICROBIOLOGY, v.75, no.10, pp.3062 - 3068 APPLIED AND ENVIRONMENTAL MICROBIOLOGY 75 10 3062 3068 scie scopus 000265908500009 2-s2.0-66249090545 Biotechnology & Applied Microbiology Microbiology Biotechnology & Applied Microbiology Microbiology Article EQUOL-PRODUCING BACTERIUM HUMAN FECES ISOFLAVONE METABOLITES ABSOLUTE-CONFIGURATIONS ANAEROBIC BACTERIUM SOY ISOFLAVONES DAIDZEIN IDENTIFICATION GENISTEIN DIHYDROGENISTEIN equol Julong 732 tetrahydrodaidzein daidzein isoflavanone isoflavan dihydrodaidzein stereoisomer