LL-Z1272alpha epoxide, a precursor of ascochlorin produced by a mutant of Ascochyta viciae

A novel metabolite, LL-Z1272alpha epoxide, structurally related to ascochlorin, was isolated from the cultured mycelium of Ascochyta viciae J-29, a mutant derived from A. viciae Libert. The structure was elucidated on the basis of spectroscopic data. The epoxide is proposed to be enzymatically formed from LL-Z1272alpha and is a precursor of ascochlorin, an antiviral and antitumor antibiotic. The conversion of the epoxide to ascochlorin by cyclization of its farnesyl chain to a cyclohexanone ring is similar to that of squalene 2, 3-oxide to sterols. Unlike ascochlorin, the new metabolite had no growth inhibitory activity against Candida albicans in the paper-disc agar diffusion assay.