Structure, absolute configuration and biological evaluation of polyoxygenated meroterpenoids from the marine algal-derived Aspergillus terreus EN-539

Two new meroterpenoids, aperterpenes N (1) and O (2), along with two known structurally related derivatives, terretonins A (3) and G (4), were isolated and identified from the marine algal-derived endophytic fungus Aspergillus terreus EN-539. Their structures and absolute configurations were determined by a detailed interpretation of spectroscopic data and by X-ray crystallographic analysis. This is the first establishment of the absolute configurations for terretonins A (3) and G (4). Compound 1 showed inhibitory activity against influenza neuraminidase (IC50 = 18.0 nM), and compound 4 showed inhibitory activity against Micrococcus luteus and Staphylococcus aureus, with MIC values of 32 and 8 mu g/mL, respectively.