Microbial transformation of curvularin.

The microbiological transformation of curvularin (1) with Beauveria bassiana ATCC 7159 afforded three new metabolites identified as curvularin-7-O-beta-D-glucopyranoside (2), curvularin-4'-O-methyl-7-O-beta-D-glucopyranoside (3), and 6-hydroxycurvularin-4'-O-methyl-6-O-beta-D-glucopyranoside (4) resulting from hydroxylation, glucosidation, and methylglucosidation of the substrate. Isolation of 6-methyl-2,4-dihydroxyphenyl-4'-O-methyl-1-O-beta-D-glucopyranoside (5) from the fermentation broth of B. bassiana ATCC 7159 without any added substrate suggested that hydroxylase, glucosyl transferase, and methylase are constitutive enzymes of this organism.