New inhibitors of RANKL-induced Osteoclastogenesis from the marine sponge Siphonochalina siphonella.

New sipholane type triterpenes, sipholenols N and O (1 and 2) and neviotine D (3), were isolated from the Red Sea marine sponge Siphonochalina siphonella along with four known triterpenes, sipholenone A (4), sipholenol A (5), siphonellinol D (6) and neviotine A (7). Structure elucidation of 1-3 was achieved by extensive 1D and 2D NMR analyses. The isolated compounds were examined for the inhibition of RANKL induced osteoclastogenesis in RAW264 macrophages. Neviotine D (3) and neviotine A (4) showed potent inhibition with IC50 values of 12.8 and 32.8 µM, respectively.