Nutrikinetics of Isoflavone Metabolites After Fermented Soybean Product (Cheonggukjang) Ingestion in Ovariectomized Mice

Scope: Cheonggukjang (CGJ) is a soybean-based quick-fermented food popular in Korea that contains a variety of biologically active compounds including isoflavones and saponins. Isoflavone bioavailability may be important for the bone health of postmenopausal women; therefore, the aim of this study is to evaluate the influence of fermentation on the isoflavone metabolite nutrikinetic profile after single dose CGJ or unfermented soybean administration in ovariectomized (OVX) and sham mice. Methods and results: We identify 34 isoflavone metabolites using UPLC-QTOF-MS and analyze their nutrikinetics at different time points (0.25, 0.5, 1, 2, 4, 8, 16, and 24 h) to understand their fermentation-and OVX-mediated time-dependent concentration changes. Nutrikinetics analysis shows that genistein, daidzein, genistein 4'-sulfate, dihydrodaidzein sulfate, equol 4'-sulfate, and equol-7-glucuronide are present at high concentrations in all groups based on area-under-the-curve analysis. OVX mice appear to show lower isoflavone bioavailability than mice in the sham group. CGJ enhances various isoflavone metabolite bioavailability including genistein, 3-hydroxygenistein, and equol 7-glucuronide, compared to the unfermented soybean-treated group. Among these metabolites, intact isoflavones, 3-hydroxygenistein, genistein 4'-sulfate, and equol 7-glucuronide promote osteoblastogenesis and inhibit osteoclast formation. Conclusions: CGJ has good isoflavone bioavailability and may be beneficial for the bone health of postmenopausal women.