Isomalabaricane-type nortriterpenoids and other constituents of the marine sponge Geodia japonica

Twelve compounds were isolated from the sponge Geodia japonica collected from the South China Sea, including two new isomalabaricane-type nortriterpenoids, geoditins A (1) and B (2), and a new sterol derivative (4). All chemical structures were established by interpretation of the spectroscopic data.