Erectsterates A and B, a pair of novel highly degraded steroid derivatives from the South China Sea soft coral Sinularia erecta.

•Two novel steroidal derivatives were isolated from the South China Sea soft coral Sinularia erecta.•Such kind of ring B-degraded steroids were isolated from the soft coral for the first time.•The main novelty of 1 and 2 is the unprecedented seven-membered lactone moiety in ring C.•Compound 2 exhibited weak cytotoxicity against HT-29, A549, SNU-398, and Capan-1 cells.