Isolation and Biological Activity of Seven New Drimane-Type Sesquiterpenoids from an Earwig-Associated Aspergillus sp. NF2396

Drimane-type sesquiterpenoids are widely distributed in fungi. From the ethyl acetate extract of the earwig-derived Aspergillus sp. NF2396, seven new drimane-type sesquiterpenoids, named drimanenoids A-G ( 1 - 7 ), were isolated. Their structures were elucidated by diverse spectroscopic analysis including high-resolution ESI-MS, one- and two-dimensional NMR spectroscopy. Drimanenoids A-F ( 1 - 6 ) are new members of drimane-type sesquiterpenoid esterified with unsaturated fatty acid side chain at C-6. The antibacterial and cytotoxic activity of these new compounds were evaluated. Compound 4 exhibited moderate cytotoxicity against human myelogenous leukemia cell line K562 with IC₅₀ values of 12.88 ± 0.11 μM.