Biosynthetic-Studies on Tajixanthone and Shamixanthone, Polyketide Hemiterpenoid Metabolites of Aspergillus variecolor

Abstract

The biosynthesis of tajixanthone and related metabolites of Aspergillus variecolor has been studied by incorporation experiments with simple and advanced precursors labelled with the stable isotopes 13C, 2H and 18O. Tajixanthone is shown to be derived through ring cleavage of an octaketide -derived anthraquinone with introduction of two dimethylallyl moieties. From the results of isotopic labelling experiments and chemical studies on model compounds, an overall biosynthetic pathway is proposed and information on the mechanisms of interconversion of proposed intermediates is obtained.