Kurilosides A1, A2, C1, D, E and F-Triterpene Glycosides from the Far Eastern Sea Cucumber Thyonidium (= Duasmodactyla) kurilensis (Levin): Structures with Unusual Non-Holostane Aglycones and Cytotoxicities

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.

Sulfated Glycosides from the Sea Cucumbers Block Ca2+ Flow in Murine Neuroblastoma Cells

Recently the ability of triterpene glycosides from sea cucumbers to interact with purinergic receptors of P2X family on the membranes of immune cells enhancing the reversible ATP-dependent Ca2+ intake and therefore modulating (stimulating) the receptor's activity was discovered. As a result the activation of cellular immunity on the organism level was observed. Purinergic receptors are associated with a series of important functions in normal and pathophysiology, thus the searching of its new modulators (both stimulants and blockers) seems to be very important medical and scientific task. The cytotoxic activity of four triterpene glycosides isolated from different species of sea cucumbers: liouvilloside A (1) from Pseudocolochirus violaceus, fallaxoside D1 (2) from Cucumaria fallax and magnumosides C3 (3) and C4 (4) from Massinium (=Neothynidium) magnum against neuroblastoma Neuro 2A cells was tested. The glycosides 1 and 4 were the most cytotoxic in the series (EC50 5.0 μM and 21.5 μM, correspondingly). Moreover, non-cytotoxic concentration (1 μM) of these compounds inhibited ATP-dependent Ca2+ intake into the Neuro 2A cells, containing P2X7 receptors on the surface, by 53 and 47%, correspondingly. The ability of sea cucumbers triterpene glycosides to block the purinergic receptors in vitro is first discovered.

Triterpene Glycosides from the Sea Cucumber Eupentacta fraudatrix. Structure and Cytotoxic action of Cucumarioside D with a Terminal 3-O-Me-Glucose Residue Unique for this Species

New minor triterpene glycoside, cucumarioside D (1) identified earlier as a candidate to new glycoside using LC-ESI QTOF-MS has been isolated from the sea cucumber Eupentacta fraudatrix as individual substance. The structure of the glycoside was elucidated using 2D NMR spectroscopy and MS. The glycoside has non-sulfated pentasaccharide carbohydrate chain branched by the second sugar (quinovose) and having 3-O-methylglucose as a terminal monosacharide residue that is an unique structural feature of sea cucumber triterpene glycosides from this species. A moderate cytotoxic activity of the glycoside 1 against the ascyte form of Echlich carcinoma cells and hemolytic activity has been found.