Triterpene glycosides from the Far Eastern sea cucumber Pentameracalcigera II: Disulfated glycosides

摘要

Three new triterpene glycosides, calcigerosides D-1 (1), D-2 (2), nd E (3), have been isolated from the sea cucumber Pentamera calcigera. Their structures have been deduced from extensive spectral analysis (NMR and MS) and chemical evidence. All the compounds are disulfated pentaosides differing in aglycon structure and position of sulfate group, which were determined by the measurement of NT1 values in the cases of glycosides 1 and 2. Glycoside 1 is a nonholostane derivative, that is, it lacks an 18(20)-lactone, which is very rare among the sea cucumber glycosides.