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

Abstract 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.