Bikaverin and norbikaverin, benzoxanthentrione pigments of Gibberella fujikuroi

Abstract

The chemical and spectroscopic characteristics of bikaverin and norbikaverin, two hydroxy-quinonoid benzoxanthones isolated from Gibberella fujikuroi and other Fusarium spp., are fully consistent with the established structures. Bikaverin forms two series of isomeric O-alkyl and O-acyl derivatives corresponding to tautomeric forms of the parent hydroxy-quinone; the related problem of proton location in the hydroxy-quinones, and in naphthazirins generally, is discussed in the light of n.m.r. data.