Steroid glycosides from the starfish Pentaceraster gracilis.

Using combined chromatographic separations, two new steroid glycosides namely pentacerosides A (1) and B (2), and four known compounds were isolated from the methanol extract of the starfish Pentaceraster gracilis. Their structures were determined on the basis of spectroscopic data ((1)H and (13)C NMR, HSQC, HMBC, (1)H-(1)H COSY, ROESY, and FT-ICR-MS) and by comparing obtained results to the literature values. Among the isolated compounds, only maculatoside (5) showed significant cytotoxic effect against Hep-G2 (IC50 = 16.75 ± 0.69 μM) and SK-Mel2 (IC50 = 19.44 ± 1.45 μM) cell lines and moderate effect on KB (IC50 = 36.53 ± 0.78 μM), LNCaP (IC50 = 39.75 ± 3.34 μM), and MCF7 (IC50 = 47.34 ± 7.01 μM) cell lines.