Macrocyclic anti-inflammatory diterpenes from the South China Sea soft coral Sinularia erecta and their isolation by combined column chromatography

Eleven new macrocyclic casbane-type diterpenes, namely sinueracasbanones E–O (1–11), have been isolated from the South China Sea soft coral Sinularia erecta using combined column chromatography. The structures of new compounds were elucidated by extensive spectroscopic data analysis, the modified Mosher's method, X-ray diffraction analysis and quantum mechanical calculation methods. In bioassay, compounds 2, 5, 10 and 11 displayed interesting anti-inflammatory activities by the inhibition of lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF)-α protein release with half maximal inhibitory concentration (IC₅₀) values of 15.6, 7.1, 13.7 and 6.6 µM, respectively.