Briavioids E-G, Newly Isolated Briarane-Diterpenoids from a Cultured Octocoral Briareum violaceum .

The chemical screening of a cultured soft coral, Briareum violaceum , led to the isolation of eight natural, briarane-related diterpenoids, including three unreported metabolites, briavioids E-G ( 1 - 3 ), and five known briaranes, briacavatolides B ( 4 ) and C ( 5 ), briaexcavatin L ( 6 ), briaexcavatolide U ( 7 ) and briarenol K ( 8 ). The structures of briaranes 1 - 8 were established using spectroscopic methods. The absolute configuration of briavioid A ( 9 ), obtained in a previous study, was reported for the first time in this study by a single-crystal X-ray diffraction analysis using a copper radiation source. The anti-inflammatory activity of briaranes 1 and 2 and briaranes 4 - 8 was evaluated by screening their inhibitory ability against the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) proteins in lipopolysaccharide (LPS)-induced RAW 264.7 macrophage cells.