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.

Seven sulfated triterpene glycosides, psolusosides B (1), E (2), F (3), G (4), H (5), H1 (6), and I (7), along with earlier known psolusoside A and colochiroside D have been isolated from the sea cucumber Psolus fabricii collected in the Sea of Okhotsk. Herein, the structure of psolusoside B (1), elucidated by us in 1989 as a monosulfated tetraoside, has been revised with application of modern NMR and particularly MS data and proved to be a disulfated tetraoside. The structures of other glycosides were elucidated by 2D NMR spectroscopy and HR-ESI mass-spectrometry. Psolusosides E (2), F (3), and G (4) contain holostane aglycones identical to each other and differ in their sugar compositions and the quantity and position of sulfate groups in linear tetrasaccharide carbohydrate moieties. Psolusosides H (5) and H1 (6) are characterized by an unusual sulfated trisaccharide carbohydrate moiety with the glucose as the second sugar unit. Psolusoside I (7) has an unprecedented branched tetrasaccharide disulfated carbohydrate moiety with the xylose unit in the second position of the chain. The cytotoxic activities of the compounds 2–7 against several mouse cell lines—ascite form of Ehrlich carcinoma, neuroblastoma Neuro 2A, normal epithelial JB-6 cells, and erythrocytes—were quite different, at that hemolytic effects of the tested compounds were higher than their cytotoxicity against other cells, especially against the ascites of Ehrlich carcinoma. Interestingly, psolusoside G (4) was not cytotoxic against normal JB-6 cells but demonstrated high activity against Neuro 2A cells. The cytotoxic activity against human colorectal adenocarcinoma HT-29 cells and the influence on the colony formation and growth of HT-29 cells of compounds 1–3, 5–7 and psolusoside A was checked. The highest inhibitory activities were demonstrated by psolusosides E (2) and F (3).

Nine new sulfated triterpene glycosides, magnumosides A1 (1), A2 (2), A3 (3), A4 (4), B1 (5), B2 (6), C1 (7), C2 (8) and C4 (9) as well as a known colochiroside B2 (10) have been isolated from the tropical Indo-West Pacific sea cucumber Neothynidium (=Massinium) magnum (Phyllophoridae, Dendrochirotida) collected in the Vietnamese shallow waters. The structures of new glycosides were elucidated by 2D NMR spectroscopy and mass-spectrometry. All the isolated new glycosides were characterized by the non-holostane type lanostane aglycones having 18(16)-lactone and 7(8)-double bond and differed from each other by the side chains and carbohydrate moieties structures. Magnumoside A1 (1) has unprecedented 20(24)-epoxy-group in the aglycone side chain. Magnumosides of the group A (1–4) contained disaccharide monosulfated carbohydrate moieties, of the group B (5, 6)—tetrasaccharide monosulfated carbohydrate moieties and, finally, of the group C (7–9)—tetrasaccharide disulfated carbohydrate moieties. The cytotoxic activities of the compounds 1–9 against mouse spleen lymphocytes, the ascites form of mouse Ehrlich carcinoma cells, human colorectal carcinoma DLD-1 cells as well as their hemolytic effects have been studied. Interestingly, the erythrocytes were more sensitive to the glycosides action than spleenocytes and cancer cells tested. The compounds 3 and 7 significantly inhibited the colony formation and decreased the size of colonies of DLD-1 cancer cells at non-cytotoxic concentrations. Moreover, the synergism of effects of radioactive irradiation and compounds 3 and 7–9 at subtoxic doses on proliferation of DLD-1 cells was demonstrated.

Six new monosulfated triterpene tetra-, penta- and hexaosides, namely, the kurilosides A1 (1), A2 (2), C1 (3), D (4), E (5) and F (6), as well as the known earlier kuriloside A (7), having unusual non-holostane aglycones without lactone, have been isolated from the sea cucumber Thyonidium (= Duasmodactyla) kurilensis (Levin) (Cucumariidae, Dendrochirotida), collected in the Sea of Okhotsk near Onekotan Island from a depth of 100 m. Structures of the glycosides were established by 2D NMR spectroscopy and HR-ESI mass spectrometry. Kurilosides of the groups A and E contain carbohydrate moieties with a rare architecture (a pentasaccharide branched by C(4) Xyl1), differing from each other in the second monosaccharide residue (quinovose or glucose, correspondingly); kurilosides of the group C are characterized by a unique tetrasaccharide branched by a C(4) Xyl1 sugar chain; and kurilosides of the groups D and F are hexaosides differing from each other in the presence of an O-methyl group in the fourth (terminal) sugar unit. All these glycosides contain a sulfate group at C-6 of the glucose residue attached to C-4 Xyl1 and the non-holostane aglycones have a 9(11) double bond and lack γ-lactone. The cytotoxic activities of compounds 1–7 against mouse neuroblastoma Neuro 2a, normal epithelial JB-6 cells and erythrocytes were studied. Kuriloside A1 (1) was the most active compound in the series, demonstrating strong cytotoxicity against the erythrocytes and JB-6 cells and a moderate effect against Neuro 2a cells.

Ten new di-, tri- and tetrasulfated triterpene glycosides, psolusosides B1 (1), B2 (2), J (3), K (4), L (5), M (6), N (7), O (8), P (9), and Q (10), were isolated from the sea cucumber Psolus fabricii collected in the Sea of Okhotsk near the Kurile Islands. Structures of these glycosides were established by two-dimensional (2D) NMR spectroscopy and HR-ESI mass-spectrometry. It is particularly interesting that highly polar compounds 9 and 10 contain four sulfate groups in their carbohydrate moieties, including two sulfates in the same terminal glucose residue. Glycoside 2 has an unusual non-holostane aglycone with 18(16)-lactone and a unique 7,8-epoxy fragment. Cytotoxic activities of compounds 1–10 against several mouse cell lines such as Ehrlich ascites carcinoma cells, neuroblastoma Neuro 2A, normal epithelial JB-6 cells, and erythrocytes were quite different depending both on structural peculiarities of these glycosides and the type of cells subjected to their actions. Psolusoside L (5), pentaoside, with three sulfate groups at C-6 of two glucose and one 3-O-methylglucose residue and holostane aglycone, is the most active compound in the series. The presence of a sulfate group at C-2 of the terminal glucose residue attached to C-4 of the first (xylose) residue significantly decreases activities of the corresponding glycosides. Psolusosides of group B (1, 2, and known psolusoside B) are inactive in all tests due to the presence of non-holostane aglycones and tetrasaccharide-branched sugar chains sulfated by C-2 of Glc4.