Structurally Diverse Macrolactams from an Antarctic Species.

Twelve new polyenic macrolactams, cyclamenols G-R ( and -), together with the known analogue cyclamenol A (), were isolated from sp. OUCMDZ-4348. Their structures were elucidated by spectroscopic analysis, quantum chemical calculations, chemical derivatizations, and Mosher's methods. The sequenced genome of OUCMDZ-4348 revealed the putative biosynthetic gene cluster of cyclamenols. It was proposed that the polycyclic natural products, cyclamenols H-R, might be formed from cyclamenols A and G through nonenzymatic intramolecular cycloadditions and oxidative cyclizations.