title: Daidzein and genistein are converted to equol and 5-hydroxy-equol by human intestinal Slackia isoflavoniconvertens in gnotobiotic rats.
abstract: Intestinal conversion of the isoflavone daidzein to the bioactive equol is exclusively catalyzed by gut bacteria, but a direct role in equol formation under in vivo conditions has not yet been demonstrated. Slackia isoflavoniconvertens is one of the few equol-forming gut bacteria isolated from humans and, moreover, it also converts genistein to 5-hydroxy-equol. To demonstrate the isoflavone-converting ability of S. isoflavoniconvertens in vivo, the metabolization of dietary daidzein and genistein was investigated in male and female rats harboring a simplified human microbiota without (control) or with S. isoflavoniconvertens (SIA). Feces, urine, intestinal contents, and plasma of the rats were analyzed for daidzein, genistein, and their metabolites. Equol and 5-hydroxy-equol were found in intestinal contents, feces, and urine of SIA rats but not in the corresponding samples of the control rats. 5-Hydroxy-equol was present at much lower concentrations than equol and the main metabolite produced from genistein was the intermediate dihydrogenistein. The plasma of SIA rats contained equol but no 5-hydroxy-equol. Equol formation had no effect on plasma concentrations of the insulin-like growth factor I. The concentrations of daidzein and genistein were considerably lower in all samples of the SIA rats than in those of the control rats. Male SIA rats had higher intestinal and fecal concentrations of the isoflavones and their metabolites than female SIA rats. The observed activity in the rat model indicates that S. isoflavoniconvertens is capable of contributing in vivo to the bioactivation of daidzein and genistein by formation of equol and 5-hydroxy-equol.
authors: Department of Gastrointestinal Microbiology, German Institute of Human Nutrition Potsdam-Rehbruecke, Nuthetal, Germany.
authors: Anastasia
authors: A
authors: Matthies
authors: Gunnar
authors: G
authors: Loh
authors: Michael
authors: M
authors: Blaut
authors: Annett
authors: A
authors: Braune
mesh_terms: D039903:Actinobacteria / Q000378:metabolism*; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D015169:Colony Count, Microbial; D060754:Equol / Q000096:biosynthesis*; D005260:Female; D019833:Genistein / Q000493:pharmacokinetics*; D005856:Germ-Free Life; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000382:microbiology*; D007529:Isoflavones / Q000493:pharmacokinetics*; D008297:Male; D051381:Rats; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D007529:Isoflavones; D060754:Equol; C004742:daidzein; D007334:Insulin-Like Growth Factor I; D019833:Genistein