Intercedensides D-I, cytotoxic triterpene glycosides from the sea cucumber Mensamaria intercedens Lampert

Six new triterpene glycosides, intercedensides D-I (1-6), were isolated from the whole bodies of the sea cucumber Mensamria intercedens Lampert, which is found in the South China Sea. Their structures were elucidated by extensive spectroscopic analysis (NMR and ESIMS) and chemical methods. Intercedensides D (1), E (2), G (4), and H (5) have a conjugated double bond system (22Z,24-diene) in the aglycon side chain, while intercedensides F (3) and 1 (6) have only a single double bond (24, 25) in this same chain. Intercedensides D-H (1-5) showed significant cytotoxicity (ED50 0.96-5.0 mu g/mL) against 10 human tumor cell lines.