Culicinin D, an Antitumor Peptaibol Produced by the Fungus Culicinomyces clavisporus, Strain LL-12I252

A group of new 10mer linear peptides, designated culicinins A−D (1−4), was isolated from the fermentation broth of the entomopathogenic fungus Culicinomyces clavisporus, strain LL-12I252. The structures of the culicinins were determined by a combination of 2D NMR and MS analysis. The major compound, culicinin D (4), exhibited selective inhibitory activity against PTEN-negative MDA468 tumor cells. Studies on the 3D structure of 4 using NOE data and computer modeling revealed a dominant conformation of the right-handed helix.