Antiosteoporotic and antioxidant activities of diterpenoids from the Vietnamese soft corals Sinularia maxima and Lobophytum crassum

Marine organisms possess bioactive potential with tremendous pharmaceutical promise. The purpose of the present study was to investigate the antioxidant (peroxyl radical-scavenging and reducing capacities) and antiosteoporotic activities of isolated constituents (1-26) from the soft corals Sinularia maxima and Lobophytum crassum on pre-osteoblastic MC3T3-E1 cells and pre-osteoclastic RAW 264.7 cells. Among the isolated compounds, 7, 9, 17, 18, and 20 (10.0 mu M) exhibited significant peroxyl radical-scavenging capacity, with TE values ranging from 4.00 +/- 0.14 to 9.06 +/- 0.33 mu M. In addition, compounds 1, 5, 7, 20, and 24 significantly stimulated the differentiation of pre-osteoblastic MC3T3-E1 cells by increasing collagen synthesis and/or mineralization functions of osteoblasts, while compounds 1, 5-8, 12, 14-22, 24, and 26 showed significant inhibition of TRAP in NF-kappa B ligand-induced osteoclastic RAW 264.7 cells, with values ranging from 99.11 +/- 1.36 to 61.54 +/- 1.61 %. These results indicate that the soft corals S. maxima and L. crassum are excellent sources among the antioxidant and antiosteoporotic marine invertebrates.