Stachybotrysin, an Osteoclast Differentiation Inhibitor from the Marine-Derived Fungus Stachybotrys sp. KCB13F013.

Two new phenylspirodrimane derivatives, stachybotrysin (1) and stachybotrylactone B (2), were isolated from the cultures of the marine-derived fungus Stachybotrys sp. KCB13F013. The structures were determined by analyzing the spectroscopic data (1D and 2D NMR and MS) and chemical transformation, including the modified Mosher's method and single-crystal X-ray structure analysis. Compound 1 exhibited an inhibitory effect on osteoclast differentiation in bone marrow macrophage cells via suppressing the RANKL-induced activation of p-ERK, p-JNK, p-p38, c-Fos, and NFATc1.