New co-metabolites of gliotoxin in Gliocladium virens

Abstract

Chromatographic separation of extracts of Gliocladium virens, grown on a medium containing [³⁵S]sulphate, has led to the identification of 5 co-metabolites of gliotoxin (1a), new to this fungus, viz. the epitrisulphide, glioto din E (1b), the 3-hydroxymethylbut-2-enyl ether (3c), didehydrogliotoxin (5), bas-N-norgliovictin (6), and the 3-methylbut-2-enyl ether of cyclo-(glycyl-L-tyrosyl)(7); the metabolites (3c), (6), and (7) are new natural products. The synthesis of the epitri- and epitetrasulphides, gliotoxin E (1b) and gliotoxin G (1c), from gliotoxin (1a) is described, as is that of the 3-methylbut-2-enyl ether (7) from cyclo-(glycyl-L-tyrosyl). The biosynthetic significance of the dioxopiperazines (6) and (7) is briefly discussed.