Roseabol a, a new peptaibol from the fungus clonostachys rosea

Abstract

A new 11 amino acid linear peptide named roseabol A (1) and the known compound 13‐ oxo‐trans‐9,10‐epoxy‐11(E)‐octadecenoic acid (2) were isolated from the fungus Clonostachys rosea. Combined NMR and MS analysis revealed that roseabol A (1) contained amino acid residues char-acteristic of the peptaibol family of peptides such as isovaline, α‐aminoisobutyric acid, hydroxypro-line, leucinol, and an N‐terminal isovaleric acid moiety. The amino acid sequence was established by a combination of NMR studies and tandem MS fragmentation analyses, and the absolute config-urations of the constituent amino acids of 1 were determined by the advanced Marfey’s method. Compound 2 showed inhibitory activity against Merkel cell carcinoma, a rare and difficult‐to‐treat type of skin cancer, with an IC50 value of 16.5 μM.