Isolation and identification of antifungal polyesters from the marine fungus Hypoxylon oceanicum LL-15G256

Cultures of the marine fungus Hypoxylon oceanicum (LL-15G256) were found to have potent antifungal activity in assays designed to detect inhibitors of fungal cell wall biosynthesis. Bio-activity guided isolation provided the macrocyclic polyesters 15G256α (1), 15G256α-1 (2) and 15G256β (3) that were partially responsible for the antifungal activity. In addition, fermentation beers contained a series of related, but unreported metabolites designated 15G256ι (4), 15G256ω (5), 15G256ο (6), 15G256α-2 (7), 15G256β-2 (8), 15G256ν (9) and 15G256π (10). Their isolation, characterization and structures are described here and a biosynthetic sequence is proposed.