Psolusosides C3 and D2

Five new triterpene glycosides, psolusosides C3 (1), D2 (2), D3 (3), D4 (4), and D5 (5), have been isolated from the sea cucumber Psolus fabricii. The structures of these glycosides were elucidated by 2-dimensional nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry. All the compounds contain hexasaccharide carbohydrate chains, differing from each other in the third monosaccharide residue: xylose was found in psolusosides of group C and glucose in group D. Aglycones of the isolated compounds belong to the holostane type, contain 9(11)-double bond and 16-keto-group and have different side chains. The hemolytic activity against mouse erythrocytes and cytotoxic activity against mouse Ehrlich carcinoma cells (ascite form) and neuroblastoma Neuro 2A cells of 1 to 5 as well as the psolusosides isolated by us earlier, C1, C2, and D1, 26-nor-25-oxo-holotoxin A1, and holotoxin A1, have been studied. Psolusosides C2, D1, and D2 (2) having the aglycones without hydroxy group in the side chain showed the strongest hemolytic action in this series. Psolusoside D3 (3) containing a peroxide group in the side chain of its aglycone was surprisingly highly cytotoxic in all the tests