Study on the biotransformation and activities of three isoflavone glycosides from Radix Astragali by human feces in vitro

Radix Astragali (RA) is used as a traditional spice and food additive, and it is also rich in isoflavone glycosides, including calycosin-7-O-glucoside, ononin and genistin, which have beneficial effects against inflammation and oxidative stress. However, most isoflavone glycosides are hydrolyzed to other metabolites by intestinal bacteria before absorbed into the body. In this study, the levels of the above three isoflavone glycosides and their aglycones in 12 RAs from different regions were analyzed by high performance liquid chromatograph (HPLC). Then, the metabolites of the three isoflavone glycosides transformed by human feces at different times were quantified by HPLC and identified by ultra-high performance liquid chromatograph coupled with high resolution mass spectrometer (UHPLC-HRMS) and nuclear magnetic resonance hydrogen spectrum (1H-NMR). Furthermore, the anti-inflammatory and antioxidant activities of the metabolites were evaluated and the possible mechanism was analyzed by network pharmacology. As a result, a total of 18 metabolites were identified and the metabolic profiles were constructed. Among them, 4 metabolites, including 3′,4′,7-trihydroxyisoflavone, pratensein, dihydrogenistein and daidzein, were separated and identified, of which the metabolic process of pratensein was discovered for the first time. The anti-inflammatory and antioxidant activity results and network pharmacology analysis showed that there was a close relationship between the activities and the metabolic profiles, especially the formation of aglycones. This study is of significance to reveal the metabolic process of the isoflavones of RA in the intestine, and also provides guidance for the metabolism of other flavonoid glycosides.