Studies on the biosynthesis of the mycotoxin austin, a meroterpenoid metabolite of Aspergillus ustus

Abstract

Incorporations of ¹³C-labelled acetates and methionine into the mycotoxin austin in cultures of Aspergillus ustus give a labelling pattern consistent with a mixed polyketide-terpenoid pathway. Incorporations of ¹⁴C and ²H labelled 3,5-dimethylorsellinate confirm the intermediary of a preformed tetraketide-derived phenolic precursor. Further information on the mechanisms involved in the modifications of both the farnesyl- and tetraketide-derived portions of the molecule are provided by incorporation studies with [1-¹³C,¹⁸O₂]acetate, [methyl-¹³C,²H₃] methionine, ¹³C,¹⁸O-labelled dimethylorsellinate,¹⁸O₂ gas and [6-¹³C,6-²H₃]mevalonic acid lactone.