Two new polyhydroxylated steroidal glycosides from the starfish Culcita novaeguineae

The chemical constituent investigation on the starfish Culcita novaeguineae resulted in the isolation of two new polyhydroxylated steroidal glycosides and two known ones. The new compounds were identified as (25S)-3-O-(2-O-methyl-β-D-xylopyranosyl)-26-O-(β-D-xylopyranosyl)-cholest-4-ene-3β,6β,7α,8,15α,16β,26-heptaol (1) and (25S)-3-O-(2-O-methyl-β-D-xylopyranosyl)-26-O-(β-D-xylopyranosyl)-cholest-4,24(28)-diene-3β,6β,7α,8,15α,16β,26-heptaol (2) and the known compounds were determined as linckosides I and H (3-4). The structures of the isolated compounds were elucidated on the basis of extensive spectroscopic studies and chemical evidence. In addition, the cytotoxicity of the two new compounds against human glioblastoma cell lines U87, U251 and SHG44 was evaluated by MTT method.