Comparison of the in vitro metabolism of isoflavones by fecal flora from human flora-associated mice and human

Recently there has been great interest in the biological effects of equol (4′,7-dihydroxyisoflavan), a metabolite of daidzein produced by intestinal flora. In this study, the in vitro metabolism of daidzein, daidzin and genistein by fecal flora, in human flora-associated (HFA) mice and a human donor was investigated. The in vitro incubation of feces with isoflavones demonstrated that the potential for equol production had been successfully transferred from human feces to HFA mice. The average equol concentrations were higher in feces from HFA mice than in those from their donor. In both HFA mice and their donor, the fecal equol production from daidzin was comparable to that from daidzein. The results suggest that daidzin would be an effective substrate for bacterial equol production in vivo. The HFA mice produced in these experiments and maintained in an isolated environment might also be useful for investigating the biological activity of equol in detail. Copyright © 2006 Society of Chemical Industry