Four undescribed specialised metabolites from the endophytic fungus Penicillium sp. and their potential antifungal activities

Culturing an endophytic Penicillium sp. recovered from Illigera celebica Miq. (Hernandiaceae) afforded four polyketide derivatives not described previously, penicitide A–D (1–4), along with the known metabolites 5 and 6. Their structures were worked out by NMR spectroscopy together with Mosher ester analysis, acetonide derivatization and ML-J-DP4 probability calculations. Compound 3 carries a 2-methyl-5-vinyltetrahydrofuran core, a motif not documented before. When tested against a panel of phytopathogens, most of the isolates suppressed fungal growth; 3 proved the most potent and warrants further attention as a starting point for environmentally benign fungicides.