Metabolites produced by the Scleroderris canker fungus, Gremmeniella abietina. Part 4. Biosynthetic studies

Abstract

The biosynthetic origin of the carbon atoms of the most highly oxidized, polyketide derived, ring (carbons 1-3) of the Gremmeniella abietina metabolites sclerodione (3), scleroderolide (4), sclerodin (5), and Scleroderris green (6) has been studied. It is shown that both C-1 and C-3 of 3 and 4 are derived from C-1 of acetate, and that C-2 of scleroderolide (4) is derived from C-2 of acetate while C-3 is derived from C-1 of acetate. As expected, C-1 and C-3 of Scleroderris green (6) originate from the carboxyl carbon of acetate, while C-2 originates from the methyl carbon of acetate. Complete 13C and 1H nuclear magnetic resonance spectra of these metabolites are reported. It has also been shown that enf-atrovenetin (ent-7a) is a metabolite of G. abietina.