Identification and structure-activity relationship (SAR) of chemical constituents from Daemonorops draco (Willd.) Blume and selected commercial flavonoids on anti-osteoclastogenesis activity.

Osteoclastogenesis-related bone diseases including osteoporosis, rheumatoid arthritis, Paget's disease and periodontitis are worldwide occurred and cause severe health problems including bone fracture and bone cancer. However, A few studies have shown that Daemonorops draco (Willd.) Blume may decrease bone destruction and relieve bone cancer pain. In this research, we isolated and purified four known and two novel compounds from D. draco and investigated their anti-osteoclastogenesis activity using RAW264.7 cells. Among them, com.1 exhibited the most effective inhibitory activity on osteoclastogenesis with 78% inhibition at 10 μM and identified to be a novel natural flavan; and com.2 displayed a bit slighter inhibition (50% at 10 μM), indicating that the methylation of 7-hydroxyl group increased the anti-osteoclastogenesis activity. Moreover, nineteen commercial flavonoids were also performed in this study to investigate their inhibitory activity on osteoclastogenesis, and furtherly develop the SAR profile in flavonoid skeleton combined with the information of isolated compounds. Interestingly, the absence of substituents in B-ring and (3R)-hydroxyl group seems to play a crucial role in increasing anti-osteoclastogenesis activity.