Structure revision and absolute configuration of 5,7--hydroxyoplopanone and anti-osteoporotic activities of sesquiterpenoids from the rhizomes of .

Five sesquiterpenoids including 2-hydroxyoplopanone , oplopanone (), 1,4,6-trihydroxy-eudesmane (), 1,4,7-trihydroxy-eudesmane () and bullatantriol () were isolated from . The structure of the previously reported compound, 5,7--2-hydroxyoplopanone (), has been revised to by the spectroscopic evidences (1D-/2D-NMR, IR, UV and HRESIMS) and by comparison between experimental and theoretical NMR data using DP4+ protocol. Furthermore, the absolute configuration of was unambiguously assigned by ECD experiments. Compounds and displayed a potent ability to stimulate osteogenic differentiation of MC3T3-E1 cells at 4 µg/mL (by 123.74% and 131.07%, respectively) and 20 µg/mL (by 112.45% and 126.41%, respectively) whilst and did not show any activities. At 20 µg/mL, and significantly promoted the mineralization of MC3T3-E1 cells with values of 112.95% and 116.37%, respectively, whereas and were inactive. The results indicated that could be an excellent component for anti-osteoporosis studies from the rhizomes of .