Drimane Sesquiterpenoids from the Fungus Aspergillus ustus Isolated from the Marine Sponge Suberites domuncula

Seven new drimane sesquiterpenoids (1-3, 6-9), along with the known compounds deoxyuvidin B (4), strobilactone B (5), and RES-1149-2 (10), were obtained from cultures of the fungus Aspergillus ustus, which was isolated from the marine sponge Suberites domuncula. Their structures were established by means of spectroscopic analyses including one- and two-dimensional NMR spectroscopy and high-resolution MS. Compounds 6, 7, and 10 showed cytotoxic activity against a panel of tumor cell lines, including L5178Y, HeLa, and PC12 cells, with 7 being the most active (EC50 against L5178Y cell line: 0.6 mu g/mL).