Triterpene Glycosides from the Far Eastern Sea Cucumber Psolus chitonoides: Chemical Structures and Cytotoxicities of Chitonoidosides E1, F, G, and H

Marine natural products

Covering: January to December 2021This review covers the literature published in 2021 for marine natural products (MNPs), with 736 citations (724 for the period January to December 2021) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1425 in 416 papers for 2021), together with the relevant biological activities, source organisms and country of origin. Pertinent reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included. An analysis of the number of authors, their affiliations, domestic and international collection locations, focus of MNP studies, citation metrics and journal choices is discussed.

The Isolation, Structure Elucidation and Bioactivity Study of Chilensosides A, A1, B, C, and D, Holostane Triterpene Di-, Tri- and Tetrasulfated Pentaosides from the Sea Cucumber Paracaudina chilensis (Caudinidae, Molpadida)

Five new triterpene (4,4,14-trimethylsterol) di-, tri- and tetrasulfated pentaosides, chilensosides A (1), A₁ (2), B (3), C (4), and D (5) were isolated from the Far-Eastern sea cucumber Paracaudina chilensis. The structures were established on the basis of extensive analysis of 1D and 2D NMR spectra and confirmed by HR-ESI-MS data. The structural variability of the glycosides concerned the pentasaccharide chains. Their architecture was characterized by the upper semi-chain consisting of three sugar units and the bottom semi-chain of two sugars. Carbohydrate chains of compounds 2–5 differed in the quantity and positions of sulfate groups. The interesting structural features of the glycosides were: the presence of two sulfate groups at C-4 and C-6 of the same glucose residue in the upper semi-chain of 1, 2, 4, and 5 and the sulfation at C-3 of terminal glucose residue in the bottom semi-chain of 4 that makes its further elongation impossible. Chilensoside D (5) was the sixth tetrasulfated glycoside found in sea cucumbers. The architecture of the sugar chains of chilensosides A–D (1–5), the positions of sulfation, the quantity of sulfate groups, as well as the aglycone structures, demonstrate their similarity to the glycosides of the representatives of the order Dendrochirotida, confirming the phylogenetic closeness of the orders Molpadida and Dendrochirotida. The cytotoxic activities of the compounds 1–5 against human erythrocytes and some cancer cell lines are presented. Disulfated chilensosides A₁ (2) and B (3) and trisulfated chilensoside C (4) showed significant cytotoxic activity against human cancer cells.

Echinoderms Metabolites: Structure, Functions and Biomedical Perspectives II

Echinoderms belong to the phylum Echinodermata (from the Ancient Greek words “echinos” (hedgehog) and “derma” (skin)) [...]

Structures and Biologic Activity of Chitonoidosides I, J, K, K1 and L-Triterpene Di-, Tri- and Tetrasulfated Hexaosides from the Sea Cucumber Psolus chitonoides

Five new triterpene di-, tri- and tetrasulfated hexaosides (chitonoidosides I (1), J (2), K (3), K₁ (4) and L (5)) were isolated from the Far-Eastern sea cucumber Psolus chitonoides, collected near Bering Island (Commander Islands) from a depth of 100–150 m. The structural variability of the glycosides concerned both the aglycones (with 7(8)- or 9(11)-double bonds) and carbohydrate chains differing from each other by the third sugar residue (Xyl or sulfated by C-6 Glc) and/or by the fourth—terminal in the bottom semi-chain—residue (Glc or sulfated by C-6 MeGlc) as well as by the positions of a sulfate group at C-4 or C-6 in the sixth—terminal in the upper semi-chain—residue (MeGlc). Hemolytic activities of these compounds 1–5 against human erythrocytes as well as cytotoxicity against human cancer cell lines, HeLa, DLD-1 and HL-60, were studied. The hexaosides, chitonoidosides K (3) and L (5) with four sulfate groups, were the most active against tumor cells in all the tests. Noticeably, the sulfate group at C-4 of MeGlc6 did not decrease the membranolytic effect of 5 as compared with 3, having the sulfate group at C-6 of MeGlc6. Erythrocytes were, as usual, more sensitive to the action of the studied glycosides than cancer cells, although the sensitivity of leukemia promyeloblast HL-60 cells was higher than that of other tumor cells. The glycosides 1 and 2 demonstrated some weaker action in relation to DLD-1 cells than against other tumor cell lines. Chitonoidoside K₁ (4) with a hydroxyl at C 25 of the aglycone was not active in all the tests. The metabolic network formed by the carbohydrate chains of all the glycosides isolated from P. chitonoides as well as the aglycones biosynthetic transformations during their biosynthesis are discussed and illustrated with schemes.