Sinulasterols A-C, three new bioactive oxygenated steroids from the South China Sea soft coral Sinularia depressa.

•Three new steroids were isolated from the Chinese soft coral Sinularia depressa.•New metabolites 1 and 2 were featured by unusual C-18 oxygenated pattern.•Two groups of C-18 functionalized steroids from the same marine organism is uncommon.•Compounds 1, 2, 4 exhibited TNF-α inhibitory activity with IC50 values of 51.1 μM, 22.7 μM and 12.1 μM, respectively.