부산대학교 도서관

Much attention has been paid to the metabolism of isoflavones daidzein and genistein with regard to the prevention of several hormone-dependent diseases. It was recently reported that several glucuronic and/or sulfuric acid conjugated metabolites of daidzein and genistein are also biologically active. In order to evaluate the beneficial effects of isoflavones on health, it is important to grasp the pharmacokinetics of isoflavone metabolites in humans. In this study, we investigated individual differences in the metabolism and disposition of biologically active metabolites after soy ingestion among 10 healthy Japanese volunteers: five men and five women aged 33-55 and 21-31 years, respectively. The principal metabolite of daidzein in plasma was the estrogenic active daidzein-7-glucuronide-4'-sulfate. Whereas the area under the curve (AUC) value of this metabolite varied 1.7-fold among subjects (4.52-7.76μmol・h/l), those of monoglucuronides of daidzein (daidzein-7-glucuronide and daidzein-4'-glucuronide) varied widely among subjects (0.90-9.40μmol・h/l). These variations would contribute to individual differences in the total AUC of daidzein. For genistein, individual differences in the total AUC were highly influenced by the estrogenic active major metabolite genistein-7-glucuronide-4'-sulfate. Because the isoflavone profiles in plasma differed greatly, it may be possible to make a difference of in the prevention of several diseases according to individual differences in the enzymatic activity that participates in the metabolism of isoflavones and the gastrointestinal permeability of isoflavones and their metabolites.