Penicillilactone A, a novel antibacterial 7-membered lactone derivative from the sponge-associated fungus Penicillium sp. LS54.

One novel 7-membered lactone derivative, penicillilactone A (1), together with two known compounds, rugulosin A (2) and rugulosin (3) were isolated from the sponge-derived fungus Penicillium sp. LS54. Their structures were elucidated on the basis of spectroscopic analysis and comparison with literature data. Remarkably, penicillilactone A (1) is the first natural product containing a 7-membered lactone ring fused with a furan core. Penicillilactone A (1) exhibited moderate antibacterial activity against aquatic pathogen Vibrio harveyi with an MIC value of 8 μg/mL.