Biosynthesis of LL-D253α, a polyketide chromanone metabolite of Phoma pigmentivora: incorporation of 13C, 2H and 18O labelled precursors
Abstract
The incorporation of 13C, 2H and 18O labelled acetates and 18O2 gas into LL-D253α, a chromanone metabolite of Phoma pigmentivora and other fungi, and analysis of the enriched metabolites by 13C and 2H NMR spectroscopy and mass spectrometry indicates its formation via two preformed polyketide chains. Evidence is presented for the mechanism of formation of the chromanone ring and a cyclopropyl intermediate is proposed to account for the unexpected randomisation of label observed in the hydroxyethyl side chain. A pathway is proposed to explain the occurrence of the co-metabolites LL-D253β and γ.