Four new triterpene glycosides, fallaxosides C1 (1), C2 (2), D1 (3) and D2 (4) along with the known cucumarioside A3-2 (5) and koreoside A (6) have been isolated from the sea cucumber Cucumaria fallax (Cucumariidae, Dendrochirotida). Structures of the glycosides have been elucidated by 2D NMR spectroscopy and mass spectrometry. All of the glycosides are rare non-holostane derivatives having shortened side chains and contain pentasaccharide carbohydrate moieties with two or three sulfate groups. Structures of these triterpene glycosides and their comparison with those earlier isolated from Cucumaria spp. and Pseudocnus dubiosus leoninus allow us to suggest that the present assignment of C. fallax to the genus Pseudocnus is not correct, and this species should be assigned to the genus Cucumaria. Cytotoxic activity of glycosides 1–5 against the ascite form of mouse Ehrlich carcinoma cells and mouse spleen lymphocytes and hemolytic activity against mouse erythrocytes have been studied. The glycosides were expectedly not active in all the tests due to the absence of an 18(20)-lactone in their aglycones and the presence of several sulfate groups. There was one exception, cucumarioside A3-2 (5), which demonstrated a weak cytotoxicity against lymphocytes and moderate hemolytic activity.
Four new trisulfated triterpene glycosides, fallaxosides D
4
(
1
), D
5
(
2
), D
6
(
3
) and D
7
(
4
) have been isolated from the sea cucumber
Cucumaria fallax
(Cucumariidae, Dendrochirotida). The structures of the glycosides have been elucidated by 2D NMR spectroscopy and HRESIMS. All the glycosides have the lanostane aglycones of a rare non-holostane type with 7(8)-, 8(9)- or 9(11)-double bonds, one or two hydroxyl groups occupying unusual positions in the polycyclic nucleus and shortened or normal side chains. The pentasaccharide carbohydrate moieties of
1
–
4
have three sulfate groups. The cytotoxic activity of glycosides
1
–
4
against the ascite form of mouse Ehrlich carcinoma cells and mouse spleen lymphocytes and hemolytic activity against mouse erythrocytes have been studied.
Three eurybathic cosmopolitan genera of echinoderms, the holothurians Elpidia, the stalked crinoids Bathycrinus and the echinoids Pourtalesia, are widely distributed in the deep Arctic Ocean. The genera Echinus and Gracilechinus occur in the Arctic only in the near-Atlantic sector of the basin. In all the five genera, there is a pronounced difference in morphology between specimens occurring at different depths. It is suggested that these differences reflect the depth-related speciation that took place following three scenarios. The genera Elpidia, Bathycrinus and Pourtalesia penetrated the Arctic Ocean at bathyal depths and subsequently dispersed down into abyssal and upwards into upper bathyal and sublittoral. The vertical dispersion of the genera Echinus and Gracilechinus went along one direction: from the sublittoral (0200 m) to the abyssal (>2000 m). In the genus Elpidia (the first scenario), new species appeared as a result of colonisation both upward and down from the bathyal. In the genera Bathycrinus and Pourtalesia (the second scenario) the radiation occurred as a result of colonization only down from the bathyal to the abyssal. In the genus Echinus and Gracilechinus (the third scenario), new species appeared along the colonization down, though not from the bathyal but from the sublittoral. Juvenile characters of shallow-water species of Echinus and Gracilechinus retain in adult deep-sea specimens. Morphological peculiarities of abyssal Bathycrinus and Pourtalesia can be related to trophic adaptations or decreasing of predators pressure in the abyssal.
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