Metabolism of daidzein and genistein by intestinal bacteria.

The isoflavones daidzein [1] and genistein [2] were fermented with human fecal bacteria under anaerobic conditions. Dihydrodaidzein [3], benzopyran-4,7-diol,3-(4-hydroxyphenyl) [4], and equol [5] were isolated from the fermentation broth of 1. Only one metabolite, dihydrogenistein [6], was isolated and characterized from the fermentation broth of 2. Metabolites 3-6 were identified by spectral methods.