Progress in the Studies of Triterpene Glycosides From Sea Cucumbers (Holothuroidea, Echinodermata) Between 2017 and 2021

Structural diversity of triterpene glycosides produced by sea cucumbers or holothurians (Holothuroidea, Echinodermata) is extremely high, although all of them are either lanostane derivatives or, rarely, products of their molecular rearrangements. The majority of them are holostane derivatives possessing an 18(20)-lanostane lactone as aglycone. They contain carbohydrate chains consisting of one to six monosaccharide units including sulfated ones. The glycosides demonstrate interesting biological activities, mainly caused by membranolytic action, namely cytotoxic, ichthyotoxic, antifungal, and hemolytic properties, as well as a series of additional effects at sub-toxic doses, including immunomodulatory, and cancer preventive. This review summarizes the literature data concerning structures and biological activities of all the new triterpene glycosides isolated from sea cucumbers during 2017 to 2021.

Aramatosides C and D, 2 Previously Undescribed Triterpene Glycosides Isolated From the Roots of Aralia armata

The 2 new oleanane-type triterpene glycosides, 23-hydroxyoleanolic acid-[28- O- β-D-glucopyranosyl]-3- O-{ β-D-glucopyranosyl-(1→2)-[ β-D-glucopyranosyl-(1→3)]- β-D-galactopyranoside}, (1) and oleanolic acid-[28- O- β-D-glucopyranosyl]-3- O-{ β-D-glucopyranosyl-(1→2)-[ β-D-glucopyranosyl-(1→3)]- β-D-galactopyranoside} (2) were isolated from the roots of Aralia armata. Their chemical structures were elucidated by using a combination of high resolution electrospray ionization mass spectrometry (HR-ESI-MS), 1 dimensional (1D), and 2 dimensional (2D) nuclear magnetic resonance spectral data, as well as by comparison with the previous literature. Compounds 1 and 2 displayed weak cytotoxic activity toward KB and HepG2 cell lines with IC50 values of 25.1 ± 1.2 and 23.7 ± 0.9 µM (for 1) and 29.5 ± 1.3 and 23.9 ± 0.7 µM (for 2), respectively, compared to that of the positive control compound, ellipticine (IC50: 1.3 ± 0.1 and 1.6 ± 0.1 µM, respectively) in in vitro assay.

THE EFFECT OF PURIFIED AMOUNT OF TRITERPENE GLYCOSIDES AND THEIR ENRICHED EXTRACT FROM LEAVES OF SILPHIUM PERFOLIATUM L. ON THE GERMINATION OF SEEDS OF WINTER WHEAT AND THE ACTIVITY OF CATALASE IN THEM

The effect of purified amount of triterpene glycosides (PATG) containing, as major components, oleanolic acid glycosides – sylphiosides B, C, E, G and extract (E) enriched with them from Silphium perfoliatum L. (Asteraceae) leaves on seed germination and catalase activity (EC 1.11.1.6) in them on two varieties of winter wheat (Tritium aestivum L.) was studied. It has been shown that, the treatment of seeds with PATG solutions at concentrations of 0.0005 and 0.001% and E at concentrations of 0.2 and 0.4% increases the intensity of their swelling within 48 hours after soaking by 3.1–5.2% compared to the control, which leads to an earlier achievement of the threshold levels necessary for the activation of metabolic processes. As a result of a study of changes in catalase activity in germinating seeds of winter wheat after 1, 3 and 7 days after soaking, it was revealed that the greatest effect of seed treatment with TG preparations in manifested after 1 and 7 days of observation, its value in relation to the control respectively is 25–35% and 35–55% depending on the variety. The stimulating effect of TG preparations on catalase activity in germinating seeds of winter wheat was established for the first time. Under the influence of treatment with TG preparations the germination energy and laboratory germination of seeds increase by 3–8 and 3–6%, respectively, depending on the variety. The data obtained make it possible to consider the total preparation of TG isolated from leaves of S. perfoliatum as promising growth promoters for pre-sowing treatment of winter wheat seeds.

New Triterpene Glycosides from the Far Eastern Starfish Solaster pacificus and Their Biological Activity

Three new triterpene glycosides, pacificusosides A–C (1–3), and three previously known triterpene glycosides, cucumariosides C1 (4), C2 (5), and A10 (6), were isolated from the alcoholic extract of the Far Eastern starfish Solaster pacificus. The structures of 1–3 were elucidated by extensive NMR and ESIMS techniques and chemical transformations. Compound 1 has a novel, unique structure, containing an aldehyde group of side chains in its triterpene aglycon. This structural fragment has not previously been found in the sea cucumber triterpene glycosides or starfish steroidal glycosides. Probably, pacificusoside A (1) is a product of the metabolism of the glycoside obtained through dietary means from a sea cucumber in the starfish. Another two new triterpene glycosides (2, 3) have closely related characteristics to sea cucumber glycosides. The cytotoxicity of compounds 1–6 was tested against human embryonic kidney HEK 293 cells, colorectal carcinoma HT-29 cells, melanoma RPMI-7951 cells, and breast cancer MDA-MB-231 cells using MTS assay. Compounds 4–6 revealed the highest cytotoxic activity against the tested cell lines, while the other investigated compounds had moderate or slight cytotoxicity. The cytotoxic effects of 2–6 were reduced by cholesterol like the similar effects of the previously investigated individual triterpene glycosides. Compounds 3, 4, and 5 almost completely suppressed the colony formation of the HT-29, RPMI-7951, and MDA-MB-231 cells at a nontoxic concentration of 0.5 µM.