Bisabolane-type sesquiterpenoids and cyclic tetrapeptide from the marine fungus Aspergillus sp. WHUF05242

Two new bisabolane-type sesquiterpenoids, aspergillolanoids A and B (1 and 2), along with a previously unreported cyclic tetrapeptide, aspergitertide A (5), and four known compounds (3, 4, 6 and 7), have been isolated from the deep-sea-derived fungus Aspergillus sp. WHUF05242. Structural elucidation of these compounds was accomplished through comprehensive spectroscopic analysis, including HR-ESIMS and 1D/2D NMR spectroscopic data. The absolute stereochemistry of 1 was unambiguously determined by single-crystal X-ray crystallographic analysis, while the chiral center configurations of 5 were resolved through time-dependent density functional theory (TDDFT)-based ECD calculations. Antimicrobial evaluation revealed that compound 7 demonstrated moderate antibacterial activity against Staphylococcus aureus with MIC value of 16 μg/mL.