The inhibitory effects of roasted black bean (Rhynchosia nulubilis) extracts on RANKL-mediated RAW264.7 cells differentiation.

This study compared the inhibitory effects of roasted black bean (Rhynchosia nulubilis, seomoktae, RoS) extracts with raw seomoktae (RaS: control) extract on RANKL-mediated RAW264.7 cell differentiation after the determination of isoflavones content as well as antioxidant and antiinflammatory activities. The RoS extracts (RoS90-20, RoS100-20, RoS110-20, and RoS120-20) had significantly (p<0.05) higher isoflavones (genistein, daidzein, and glycitein) and better antioxidant activity than the RaS extract. Especially, RoS110-20, which was roasted at 110°C for 20 min, has the highest amounts of soy-derived compounds. The RoS110-20 extract significantly reduced LPS-induced nitric oxide (NO) and prostaglandin (PGE2) production compared to the RaS extract. The RoS110-20 extract showed a higher inhibitory effect on the expression of NFATc1 in RANKL-induced RAW 264.7 cells than the RaS extract without any evidence of cytotoxicity under western blotting and tartrateresistant acid phosphatase staining (TRAP). The results of this study suggest that roasting increased the concentration of soy-derived compounds and improved the antioxidant and anti-inflammatory activities of RoS110-20 extract compared with RaS. In addition, the differentiation of RANKL-mediated RAW264.7 cells was effectively inhibited by the RoS110-20 extract due to its enhanced antioxidant and anti-inflammatory activities caused by roasting, confirming its potential for ameliorating bone loss.