Triterpene glycosides from the Far-Eastern sea cucumber Pentamera calcigera. 1. Monosulfated glycosides and cytotoxicity of their unsulfated derivatives

Three new monosulfated triterpene glycosides, calcigerosides B (2), C-1 (3) , and C-2 (4), along with the known cucumarioside G(2) (1), have been isola ted from the sea cucumber Pentamera calcigera. Their structures have been d educed from extensive spectral analysis (NMR and MS) and chemical evidence. Compounds 2-4 present a novel pentasacharide chain never-reported before i n sea cucumber triterpene glycosides. The desulfated derivatives of calcige rosides B, C-1, and C-2 (5, 7, and 9, respectively) showed moderate cytotox icity (IC50 = 5 mu g/mL) against a selection of four human and mouse tumor cell lines.