New ophiobolin sesterterpenoid and drimane sesquiterpenoids from a marine-alga-derived fungus Aspergillus sp.

Further investigation of secondary metabolites of a marine-alga-derived fungus Aspergillus sp. RR-YLW-12 led to isolate one new ophiobolin-type sesterterpenoid (1), four new drimane-type sesquiterpenoids (2 – 5) and one natural occurring compound (6), together with seven known compounds (7 – 13). Their structures and stereochemistry were elucidated by extensive spectroscopic analysis of NMR and HRMS experiments, and by comparison with the literature data. All isolates were evaluated for growth inhibition of five marine harmful microalgae. The new compounds exhibited significant to moderate inhibitory effects towards all tested microalgae species with IC 50 values ranging from 5.8 to 54.5 μg/mL. [Display omitted] • Five new terpenoids were isolated from a marine-alga-derived fungus Aspergillus sp. RR-YLW-12. • Their structures were elucidated by NMR, HR-MS and ECD analysis. • The isolates displayed significant to moderate inhibitory effects against five marine harmful microalgae species. [ABSTRACT FROM AUTHOR]