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 cadinenens, (+)‐11‐hydroxy‐epicubenol (1 ) and (+)‐12‐hydroxy‐epicubenol (2 ) were elucidated by 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 liverworth. The discovery of oxygenated cadinanes from a bacterial endophyte may set the basis for the production of cadinanes by bacterial fermentation.