Bicycloalternarenes produced by the phytopathogenic fungus Alternaria alternata.

We succeeded in the isolation and structure elucidation of nine novel tricycloalternarenes from the culture filtrate of the phytopathogenic fungus Alternaria alternata, isolated from Brassica sinensis. Tricycloalternarenes are closely related to ACTG-toxins. Structural differences mainly occur in the isoprenoid side chain and the substitution pattern of the C-ring of the tricycloalternarenes.