[Structure and biological activity of glycosphingolipids from starfish and feather stars]

Obesity and lipid metabolism in the development of osteoporosis (Review)

Osteoporosis is a common bone metabolic disease that causes a heavy social burden and seriously threatens life. Improving osteogenic capacity is necessary to correct bone mass loss in the treatment of osteoporosis. Osteoblasts are derived from the differentiation of bone marrow mesenchymal stem cells, a process that opposes adipogenic differentiation. The peroxisome proliferator‑activated receptor γ and Wnt/β‑catenin signaling pathways mediate the mutual regulation of osteogenesis and adipogenesis. Lipid substances play an important role in the occurrence and development of osteoporosis. The content and proportion of lipids modulate the activity of immunocytes, mainly macrophages, and the secretion of inflammatory factors, such as IL‑1, IL‑6 and TNF‑α. These inflammatory effectors increase the activity and promote the differentiation of osteoclasts, which leads to bone imbalance and stronger bone resorption. Obesity also decreases the activity of antioxidases and leads to oxidative stress, thereby inhibiting osteogenesis. The present review starts by examining the bidirectional differentiation of BM‑MSCs, describes in detail the mechanism by which lipids affect bone metabolism, and discusses the regulatory role of inflammation and oxidative stress in this process. The review concludes that a reasonable adjustment of the content and proportion of lipids, and the alleviation of inflammatory storms and oxidative damage induced by lipid imbalances, will improve bone mass and treat osteoporosis.

Sulfated Polyhydroxysteroid Glycosides from the Sea of Okhotsk Starfish Henricia leviuscula spiculifera and Potential Mechanisms for Their Observed Anti-Cancer Activity against Several Types of Human Cancer Cells

Three new monosulfated polyhydroxysteroid glycosides, spiculiferosides A (1), B (2), and C (3), along with new related unsulfated monoglycoside, spiculiferoside D (4), were isolated from an ethanolic extract of the starfish Henricia leviuscula spiculifera collected in the Sea of Okhotsk. Compounds 1-3 contain two carbohydrate moieties, one of which is attached to C-3 of the steroid tetracyclic core, whereas another is located at C-24 of the side chain of aglycon. Two glycosides (2, 3) are biosides, and one glycoside (1), unlike them, includes three monosaccharide residues. Such type triosides are a rare group of polar steroids of sea stars. In addition, the 5-substituted 3-OSO3-α-L-Araf unit was found in steroid glycosides from starfish for the first time. Cell viability analysis showed that 1-3 (at concentrations up to 100 μM) had negligible cytotoxicity against human embryonic kidney HEK293, melanoma SK-MEL-28, breast cancer MDA-MB-231, and colorectal carcinoma HCT 116 cells. These compounds significantly inhibited proliferation and colony formation in HCT 116 cells at non-toxic concentrations, with compound 3 having the greatest effect. Compound 3 exerted anti-proliferative effects on HCT 116 cells through the induction of dose-dependent cell cycle arrest at the G2/M phase, regulation of expression of cell cycle proteins CDK2, CDK4, cyclin D1, p21, and inhibition of phosphorylation of protein kinases c-Raf, MEK1/2, ERK1/2 of the MAPK/ERK1/2 pathway.

Fatty Acids of Echinoderms: Diversity, Current Applications and Future Opportunities

The phylum Echinodermata comprising the classes Asteroidea, Ophiuroidea, Echinoidea, Holothuroidea, and Crinodeia, is one of the important invertebrate groups. Members of this phylum live exclusively in marine habitats and are distributed in almost all depths and latitudes. Some of them, such as sea urchins and sea cucumbers, are commercially valuable and constitute a major fishery resource. Echinoderms are increasingly recognized as a unique source of various metabolites with a wide range of biological activities. The importance of dietary polyunsaturated fatty acids, such as eicosapentaenoic acid, in human health has drawn attention to echinoderms as a promising source of essential fatty acids (FAs). Extensive information on the FAs of the phylum has been accumulated to date. The biosynthetic capabilities and feeding habits of echinoderms explain the findings of the unusual FAs in them. Certain common and unusual FAs may serve as chemotaxonomic markers of the classes. The main goal of the review was to gather the relevant information on the distribution of FAs among the echinoderm classes, describe the structures, distribution, biosynthetic pathways, and bioactivity, with an emphasis on the FAs specific for echinoderms. A large part of the review is devoted to the FAs derived from echinoderms that exhibit various biological activities promising for potential therapeutic applications.

New Ceramides and Cerebrosides from the Deep-Sea Far Eastern Starfish Ceramaster patagonicus

Three new ceramides (1−3) and three new cerebrosides (4, 8, and 9), along with three previously known cerebrosides (ophidiocerebrosides C (5), D (6), and CE-3-2 (7)), were isolated from a deep-sea starfish species, the orange cookie starfish Ceramaster patagonicus. The structures of 1−4, 8, and 9 were determined by the NMR and ESIMS techniques and also through chemical transformations. Ceramides 1−3 contain iso-C21 or C23 Δ9-phytosphingosine as a long-chain base and have C16 or C17 (2R)-2-hydroxy-fatty acids of the normal type. Cerebroside 4 contains C22 Δ9-sphingosine anteiso-type as a long-chain base and (2R)-2-hydroxyheptadecanoic acid of the normal type, while compounds 8 and 9 contain saturated C-17 phytosphingosine anteiso-type as a long-chain base and differ from each other in the length of the polymethylene chain of (2R)-2-hydroxy-fatty acids of the normal type: C23 in 8 and C24 in 9. All the new cerebrosides (4, 8, and 9) have β-D-glucopyranose as a monosaccharide residue. The composition of neutral sphingolipids from C. patagonicus was described for the first time. The investigated compounds 1−3, 5−7, and 9 exhibit slight to moderate cytotoxic activity against human cancer cells (HT-29, SK-MEL-28, and MDA-MB-231) and normal embryonic kidney cells HEK293. Compounds 2, 5, and 6 at a concentration of 20 µM inhibit colony formation of MDA-MB-231 cells by 68%, 54%, and 68%, respectively. The colony-inhibiting activity of compounds 2, 5, and 6 is comparable to the effect of doxorubicin, which reduces the number of colonies by 70% at the same concentration.

Sphingolipids of Asteroidea and Holothuroidea: Structures and Biological Activities

Sphingolipids are complex lipids widespread in nature as structural components of biomembranes. Commonly, the sphingolipids of marine organisms differ from those of terrestrial animals and plants. The gangliosides are the most complex sphingolipids characteristic of vertebrates that have been found in only the Echinodermata (echinoderms) phylum of invertebrates. Sphingolipids of the representatives of the Asteroidea and Holothuroidea classes are the most studied among all echinoderms. In this review, we have summarized the data on sphingolipids of these two classes of marine invertebrates over the past two decades. Recently established structures, properties, and peculiarities of biogenesis of ceramides, cerebrosides, and gangliosides from starfishes and holothurians are discussed. The purpose of this review is to provide the most complete information on the chemical structures, structural features, and biological activities of sphingolipids of the Asteroidea and Holothuroidea classes.

Sphingolipids in food and their critical roles in human health

Sphingolipids (SLs) are ubiquitous structural components of cell membranes and are essential for cell functions under physiological conditions or during disease progression. Abundant evidence supports that SLs and their metabolites, including ceramide (Cer), ceramide-1-phosphate (C1P), sphingosine (So), sphingosine-1-phosphate (S1P), are signaling molecules that regulate a diverse range of cellular processes and human health. However, there are limited reviews on the emerging roles of exogenous dietary SLs in human health. In this review, we discuss the ubiquitous presence of dietary SLs, highlighting their structures and contents in foodstuffs, particularly in sea foods. The digestion and metabolism of dietary SLs is also discussed. Focus is given to the roles of SLs in both the etiology and prevention of diseases, including bacterial infection, cancers, neurogenesis and neurodegenerative diseases, skin integrity, and metabolic syndrome (MetS). We propose that dietary SLs represent a "functional" constituent as emerging strategies for improving human health. Gaps in research that could be of future interest are also discussed.