Isolation and structures of 1,2,3,4-tetrahydro-1,4-dioxopyrazino[1,2-a]indoles from cultures of Penicillium terlikowskii

Abstract

Cultures of Penicillium terlikowskii have been examined for the presence of 1,2,3,4-tetrahydro-1,4-dioxopyrazino-[1,2-a]indoles, as there are theoretical reasons for these being intermediates in the biosynthesis of antibiotics like gliotoxin. Four fractions have been isolated from cultures of the fungus with the required properties, and the structures of three crystalline metabolites obtained therefrom have been determined. One of these (III; R¹= OH, R²= H, X = CH₂) has the structure postulated for the biosynthetic intermediate of gliotoxin. A number of tetrahydro-1,4-dioxopyrazino[1,2-a]indoles have been synthesised during this work; these syntheses and the physical properties of the compounds are given.