Aspermicrones A-C, novel dibenzospiroketals from the seaweed-derived endophytic fungus Aspergillus micronesiensis

Chemical investigation of the Kappaphycus alvarezii-derived endophytic fungus Aspergillus micronesiensis lead to the isolation of three novel dibenzospiroketals, aspermicrones A-C (1-3). Their chemical structures were determined by extensive analysis of HR-ESI-MS and NMR spectral data. The absolute configurations of them were determined by experimental and TD-DFT theoretical calculated circular dichroism spectra. Compound 2 exhibited selective cytotoxic effect toward HepG2 cell line (IC50 = 9.9 mu M). Additionally, both of compounds 2 and 3 displayed anti-microbial activity against Staphylococcus aureus (MIC = 123.2 mu M for each compound). Compound 1 was inactivity in both cytotoxic and antimicrobial assays.