Isocoumarin derivatives and benzofurans from a sponge-derived Penicillium sp. fungus.

Ten new fungal metabolites, including three hydroisocoumarins, penicimarins A-C (1-3), three isocoumarins, penicimarins D-F (6-8), and four benzofurans, penicifurans A-D (11-14), together with four known isocoumarin derivatives (4, 5, 9, 10), were obtained from the sponge-derived fungus Penicillium sp. MWZ14-4, collected from the South China Sea. Their planar structures and relative configurations were elucidated by detailed analysis of spectroscopic data and by comparison with related known compounds. The absolute configurations of 1-4 were assigned by the modified Mosher's method and TDDFT ECD calculations together with comparison of their CD spectra. Compound 1 represents a rare naturally occurring isocoumarin derivative with 4-substitution, but no substituent at the 3-position. These compounds were evaluated for antibacterial activities and cytotoxic activities in vitro. Among them, penicifuran A (11) exhibited inhibitory activity against Staphylococcus albus with an MIC value of 3.13 μM.