Biosynthesis and biogenetic interrelationships of metabolites of the fungus Arthropsistruncata

Abstract

The incorporation of sodium [1-13C]acetate and sodium [1,2-13C2]acetate into a number of polyketide metabolites produced by the fungus Arthropsistruncata has been examined. The location of sodium [1-13C]acetate incorporation into arthropsadiol A (1), cycloarthropsone (2), and arthropsatriol C (3) has been determined by 13C nuclear magnetic resonance spectra of the corresponding diacetate derivatives, and a biosynthetic pathway is proposed to account for the formation of 1–3. Multiple incorporation of sodium [1,2-13C2]acetate into arthropsadiol A (1) leads to a complicated pattern of satellite multiplets in the 13C nmr spectrum of the corresponding diacetate 6 that are interpreted with the aid of 2D-INADEQUATE spectra. A biosynthesis of arthropsolide A (5) is proposed and the absence of 5 and related metabolites in cultures of the Arthropsistruncata fed with 13C-labelled sodium acetate is discussed.