Osteogenic activities of genistein derivatives were influenced by the presence of prenyl group at ring A

Our recent report indicated that the crude extract from stem bark of Erythrina variegata L. (Leguminosae) (EV) exerted beneficial effects against osteoporosis induced by estrogen deficiency in vivo. Follow-up phytochemical study has isolated genistein-derivatives mainly in the form of prenylgenistein from this extract, including 6-prenylgenistein, 8-prenylgenistein, and 6, 8-diprenylgenistein. The present study was performed to investigate the structure-function relationship of these compounds on osteoblastic proliferation, differentiation and mineralization in UMR 106 cells. Our results showed that genistein did not stimulate cell growth while 8-prenylgenistein promoted cell growth significantly by 10∼23%. In contrast, the treatment by 6-prenylgenistein for 48 h reduced UMR 106 cell proliferation when compared to cells treated with genistein. The proliferation of 6,8-diprenylgenistein-treated cells was greater than those treated by 6-prenylgenistein at all testing concentrations. For ALP activity, significant increase was found in cells treated by either 8-prenylgenistein or 6,8-diprenylgenistein for 48 h at the concentration of 10-10M. In mineralization study, the content of Ca and P in extracellular matrix were significantly increased in 8-prenylgenistein treated cells. The results showed that genistein derivatives isolated from EV demonstrated stimulatory effects on osteogenesis in UMR 106 cells. Based on the study of structure-activity relationship, it appears that prenylation at C-8, but not at C-6, could increase the bone-protective effect of genistein.