Biosynthesis of austocystin D in Aspergillus ustus. A carbon-13 nuclear magnetic resonance study

Abstract

The assignment of the natural-abundance ¹³C n.m.r. spectrum of austocystin D, a mycotoxin produced by Aspergillus ustus MRC 1163, allowed a study of its biosynthetic origin. The complete ¹³C–¹³C coupling pattern in austocystin D enriched from [1,2-¹³C₂]acetate has been determined and confirms that no randomisation of labelling in ring A occurs during the anthraquinone → xanthone conversion in the biosynthetic pathway.