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.