Cytotoxic Polyhydroxysteroidal Glycosides from Starfish Culcita novaeguineae.

Four new polyhydroxysteroidal glycosides-culcinosides A-D (, , , and )-along with three known compounds-echinasteroside C (), linckoside F (), and linckoside L3 ()-were isolated from the ethanol extract of starfish collected from the Xisha Islands of the South China Sea. The structures of new compounds were elucidated through extensive spectroscopic studies and chemical evidence, especially two-dimensional (2D) NMR techniques. The cytotoxicity of the new compounds against human glioblastoma cell lines U87, U251, and SHG44 were evaluated.