Isolation, structure determination, and phytotoxicity of unusual dioxopiperazines from the phytopathogenic fungus Phoma lingam.

The isolation, chemical structure elucidation, and bioactivity of polanrazines B-F, five new dioxopiperazines produced by isolates of the blackleg fungus [Phoma lingam, perfect stage Leptosphaeria maculans (Desm.) Ces. et de Not.] originating from Poland, are reported. Polanrazines C and E showed moderate but selective toxicity, causing necrotic and chlorotic lesions (1-3 mm diameter) on brown mustard leaves.