Biosynthesis of Chaetochromin A, a Bis(naphtho-y-pyrone), in Chaetomium spp

Abstract

The biosynthesis of chaetochromin A, a metabolite of Chaetomium gracile, has been studied using [13CH3]methionine, sodium [l-13C]acetate, sodium [l,2-13C2]acetate, sodium [l-13C,2,2,2-2H3]acetate, and sodium [l-13C,l,l-1802]acetate as precursors. The folding pattern of the polyketide chain in chaetochromin A, biosynthesized from sodium [1,2-1 3 C2] acetate as the precursor, was determined to be the same as that of rubrofusarin by carbon-13 nuclear magnetic resonance (13C-NMR) analysis. By using [13CH3]methionine as a precursor, the source of 2-CH3 was determined. When sodium [l-I3C,2,2,2-2H3]acetate was fed, a β-isotope-shifted peak was observed only for carbon 2. In the 13C-NMR spectra of chaetochromin A and of its hexamethyl ether derived from sodium [l-13C,l,l-1802]acetate, isotope-shifted peaks were observed for carbons 4, 5,6,8 and 10a, but not for carbon 2. These results showed that oxygen 1 originated from the same unit of acetate as carbon 10a. © 1989, The Pharmaceutical Society of Japan. All rights reserved.