Plant‐like cadinane sesquiterpenes from an actinobacterial mangrove endophyte

Cadinanes are typical plant sesquiterpenes with a broad range of biological functions. We report the isolation of three cadinanes ( 1–3 ) from a bacterial endophyte (Streptomyces sp.) of the mangrove plant Bruguiera gymnorrhiza. The structures of two new cadinenes, (+)‐11‐hydroxy‐epicubenol ( 1 ) and (+)‐12‐hydroxy‐epicubenol ( 2 ) were elucidated by nuclear magnetic resonance (NMR) and mass spectrometry. The bacterial product (+)‐11‐hydroxy‐epicubenol was elucidated to be an enantiomer of the plant product pubinernoid C. (+)‐12‐Hydroxy‐epicubenol was established as a diastereomer of the basidiomycete product trichapargin A. In addition, a crystal structure analysis corroborated the structure and configuration of 5,11‐epoxy‐10‐cadinanol ( 3 ), a cadinane cycloether initially described as a natural product from liverwort. The discovery of oxygenated cadinanes from a bacterial endophyte may set the basis for the production of cadinanes by bacterial fermentation.