Biosynthesis of aspyrone and asperlactone, pentaketide metabolites of Aspergillus melleus. Incorporation studies with [1-13C, 18O2]acetate and 18O2 gas

Abstract

Incorporation of [1-13C,18O2] acetate and 18O2 gas into aspyrone (1) and asperlactone (2) by cultures of Aspergillus melleus and observation of 18O isotope-induced shifts in the 13C n.m.r. spectra of the enriched metabolites establish the origins of all the oxygen atoms and suggest a biosynthetic pathway involving epoxide-mediated rearrangement and ring closure reactions.