Sinunanolobatone A, an Anti-inflammatory Diterpenoid with Bicyclo[13.1.0]pentadecane Carbon Scaffold, and Related Casbanes from the Sanya Soft Coral Sinularia nanolobata .

A novel diterpenoid, sinunanolobatone A ( 1 ), featuring an unprecedented bicyclo[13.1.0]pentadecane carbon framework, along with two new casbane diterpenoids ( 2 and 3 ), and five known related ones ( 4 - 8 ) were isolated from the Sanya soft coral Sinularia nanolobata . The structures of the new compounds were established by detailed spectroscopic analysis, X-ray diffraction analysis, chemical reactions, or a quantum chemical computation method. A plausible biosynthetic pathway of 1 was proposed. In bioassay, the novel compound 1 showed significant inhibitory activity against lipopolysaccharide (LPS) induced inflammation in BV-2 microglial cells.