NAPHTHAQUINONE BIOSYNTHESIS IN MOULDS: THE MECHANISM FOR FORMATION OF JAVANICIN

Abstract

The following compounds, added to the growth medium of Fusarium javanicum, were converted into labelled javanicin with the percentage incorporations noted in parentheses: [Me-C14]methionine (0.83); [1-C14]acetate (0.70); [2-Cl4]malonate (0.07). Labelled samples of javanicin were degraded by Zeisel reaction, Kuhn-Roth oxidation and reaction with sodium hypoiodite; acetic acid obtained from the Kuhn-Roth reaction was further degraded by the Schmidt reaction. Labelled methionine was used only for the formation of the methoxyl group, and the remaining carbon atoms were derived by the acetate-plus-polymalonate pathway. The methyl group attached directly to the naphthaquinone ring is derived by the reduction of a carboxyl group. The demonstration of this biosynthetic pathway supports the assignment of the methoxyl group at position 7.