Two new sterol derivatives isolated from the endophytic fungus Aspergillus tubingensis YP-2

Two new sterol derivatives, namely ergosterimide B (1) and demethylincisterol A₅ (2), along with eleven known metabolites (3-13), were isolated from the rice fermentation culture of Aspergillus tubingensis YP-2. The chemical structures were elucidated by detailed NMR and MS spectroscopic data and by comparison with reported data. Newly isolated compound 2 and known compound 3 were evaluated for their cytotoxicities against the A549 and HepG2 cell lines. Compound 2 showed weak activities with IC₅₀ values of 11.05 and 19.15 μM, respectively, while 3 exhibited cytotoxicities with IC₅₀ values of 5.34 and 12.03 μM, respectively, against the tested cell lines.