Synthesis and Structural Revision of a Natural Tetrasaccharide from Starfish Asterias rollestoni Bell.

Starfish provide important saponins with diverse bioactivities as the secondary metabolites, among which 2-O-glycosylated glycosides are commonly found. Preparation of those 1,2-trans 2-O-glycosylated glycosides usually relies on 2-O-acyl participation requiring the selective installation and cleavage of 2-O-acyl groups. A convergent synthesis using 2-O-glycosylated oligosaccharide donors would be more straightforward but also pose greater challenges. Herein, we report a convergent synthesis of a distinctive tetrasaccharide isolated from starfish Asterias rollestoni Bell. Dual 2-(diphenylphosphinoyl)acetyl (DPPA) groups at O3 and O4 on galactose moiety led to high ß-selectivities (ß/α=12/1 or ß only) in the challenging [2+2] glycosylation, giving the desired tetrasaccharides in >90 % yields from the 2-O-glycosylated disaccharide donors. These synthetic studies have also unambiguously revised the structure of these natural tetrasaccharides. This work would facilitate further studies on new inhibitors of α-glucosidase as hypoglycemic drugs.

Extraction, Characterization and Osteogenic Activity of a Type I Collagen from Starfish (Asterias amurensis).

Outbreaks of starfish (Asterias amurensis) pose a major threat to aquaculture and marine ecosystems in Qingdao, China, and no effective methods have been found to control them. A comprehensive study of collagen in starfish could be an alternative to high efficient utilization. Based on this, collagen was firstly extracted from Qingdao A. amurensis. Then, its protein pattern, amino acid composition, secondary structure, microstructure and thermal stability were investigated. The results showed that the A. amurensis collagen (AAC) is a type I collagen composed of α1, α2, and ß chains. Glycine, hydroxyproline, and alanine were the major amino acids. The melting temperature was 57.7 °C. From FTIR, UV spectra and CD chromatography, the AAC had an intact triple helix and secondary structure, and microstructural analysis showed that the AAC had a loose, fibrous porous structure. Next, the osteogenic differentiation effect of AAC on Mouse bone marrow stem cells (BMSCs) was investigated, and the results showed that AAC induced osteogenic differentiation of cells by promoting the proliferation of BMSCs, enhancing alkaline phosphatase (ALP) activity, promoting cell mineralization nodules and upregulating the expression of mRNA of relevant osteogenic genes. These results suggest that AAC might have the potential application to bone health-related functional foods.

Six new polyhydroxylated steroids conjugated with taurine, microdiscusols A-F, from the Arctic starfish Asterias microdiscus.

Six new polyhydroxylated steroids conjugated with taurine, microdiscusols A-F, were isolated from the alcoholic extract of the Arctic starfish Asterias microdiscus. Three of them have been found to have additional sulfate groups in tetracyclic cores. The structures of new compounds were established by 1D and 2D NMR and HRESIMS techniques. The found steroid taurine conjugates resemble, by their structures, salts of bile acids and alcohols of lower vertebrates.

A unique structural distribution pattern discovered for the cerebrosides from starfish Asterias amurensis.

Cerebroside is an important family of the mono-glycosylated ceramides involved in the larger family of glycosphingolipid and sulfatide. Cerebroside is synthesized from ceramide by the transfer of glucose from UDP-glucose, and degraded back to ceramide, which plays an important role at the epidermis protecting interior of the body as a barrier. Because cerebroside is regarded as the source molecule of ceramide and is amphiphilic in nature, cerebroside is considered valuable as the ingredient of cosmetic lotion. Various sources can be considered as raw material of cerebrosides. Starfish is considered as one of such potent source. However, the structure of the ceramide part of cerebroside is not fully investigated. Therefore, the individual structures of cerebroside molecules need to be identified including sphingosine and fatty acyl group composition to assess the potential of the molecule. We investigated and determined the structures of cerebrosides in starfish Asterias amurensis using LC-MS, GC-MS, tandem mass spectrometry (MS/MS), and 1H NMR. We also discovered a characteristic structure distribution that was divided into three major groups: 1) a group composed of a relatively long sphingosine (C22) and a short length of fatty acyl group (less than C16), 2) a group composed of a typical C18 sphingosine and long fatty acyl groups (greater than C23), and 3) a group composed of C18 sphingosine and fatty acyl groups with their length less than C18. The calculated Log P values of cerebrosides ranging from 9 to 11 covered about 80% of the molecules that were in the range of those used in cosmetics, thus showing the potential usefulness of starfish Asterias amurensis as a source of raw material for cerebrosides.

Effects of Asterias amurensis-derived Sphingoid Bases on the de novo Ceramide Synthesis in Cultured Normal Human Epidermal Keratinocytes.

Asterias amurensis starfish provide several bioactive species in addition to being fishery waste. Glucosyl ceramides (GlcCers) were extracted from the viscera of these starfish and were isolated by silica gel column chromatography. Degraded GlcCers generated A. amurensis sphingoid bases (ASBs) that mainly consisted of the triene-type bases d18:3 and 9-methyl-d18:3. The effect of these bases on ceramide synthesis and content were analyzed using normal human epidermal keratinocytes (NHEKs). The bases significantly enhanced the de novo ceramide synthesis and gene expression in NHEKs for proteins, such as serine-palmitoyltransferase and ceramide synthase. Total ceramide, GlcCer, and sphingomyelin contents increased dramatically upon ASB treatment. In particular, GlcCer bearing very-long-chain fatty acids (≥C28) exhibited a significant content increase. These ASB-induced enhancements on de novo ceramide synthesis were only observed in undifferentiated NHEKs. This stimulation of the de novo sphingolipid synthesis may improve skin barrier functions.

Transport and uptake effects of marine complex lipid liposomes in small intestinal epithelial cell models.

Nowadays, marine complex lipids, including starfish phospholipids (SFP) and cerebrosides (SFC) separated from Asterias amurensis as well as sea cucumber phospholipids (SCP) and cerebrosides (SCC) isolated from Cucumaria frondosa, have received much attention because of their potent biological activities. However, little information is known on the transport and uptake of these lipids in liposome forms in small intestinal cells. Therefore, this study was undertaken to investigate the effects of these complex lipid liposomes on transport and uptake in Caco-2 and M cell monolayer models. The results revealed that SFP and SCP contained 42% and 47.9% eicosapentaenoic acid (EPA), respectively. The average particle sizes of liposomes prepared in this study were from 169 to 189 nm. We found that the transport of the liposomes across the M cell monolayer model was much higher than the Caco-2 cell monolayer model. The liposomes consisting of SFP or SCP showed significantly higher transport and uptake than soy phospholipid (soy-PL) liposomes in both Caco-2 and M cell monolayer models. Our results also exhibited that treatment with 1 mM liposomes composed of SFP or SCP for 3 h tended to increase the EPA content in phospholipid fractions of both differentiated Caco-2 and M cells. Moreover, it was also found that the hybrid liposomes consisting of SFP/SFC/cholesterol (Chol) revealed higher transport and uptake across the M cell monolayer in comparison with other liposomes. Furthermore, treatment with SFP/SFC/Chol liposomes could notably decrease the trans-epithelial electrical resistance (TEER) values of Caco-2 and M cell monolayers. The present data also showed that the cell viability of differentiated Caco-2 and M cells was not affected after the treatment with marine complex lipids or soy-PL liposomes. Based on the data in this study, it was suggested that marine complex lipid liposomes exhibit prominent transport and uptake in small intestinal epithelial cell models.

Inter- and intra-organ spatial distributions of sea star saponins by MALDI imaging.

Saponins are secondary metabolites that are abundant and diversified in echinoderms. Mass spectrometry is increasingly used not only to identify saponin congeners within animal extracts but also to decipher the structure/biological activity relationships of these molecules by determining their inter-organ and inter-individual variability. The usual method requires extensive purification procedures to prepare saponin extracts compatible with mass spectrometry analysis. Here, we selected the sea star Asterias rubens as a model animal to prove that direct analysis of saponins can be performed on tissue sections. We also demonstrated that carboxymethyl cellulose can be used as an embedding medium to facilitate the cryosectioning procedure. Matrix-assisted laser desorption/ionization (MALDI) imaging was also revealed to afford interesting data on the distribution of saponin molecules within the tissues. We indeed highlight that saponins are located not only inside the body wall of the animals but also within the mucus layer that probably protects the animal against external aggressions. Graphical Abstract Saponins are the most abundant secondary metabolites in sea stars. They should therefore participate in important biological activities. Here, MALDI imaging is presented as a powerful method to determine the spatial distribution of saponins within the animal tissues. The inhomogeneity of the intra-organ saponin distribution is highlighted, paving the way for future elegant structure/activity relationship investigations.

[Effect of starfish (Asterias amurensis) intake on weight gain and blood biochemical values in rats].

We observed the effect of starfish (Asterias amurensis) intake during 67 days, on rats, in terms of the activity of enzymes related to liver function and biochemical values related to weight gain, lipid metabolism and safety. 1. Starfish (Asterias amurensis) did not induce a significant difference of body weight change. 2. Starfish (Asterias amurensis) intake did not affect organ weight. 3. Starfish (Asterias amurensis) intake did not affect lipid metabolism, liver function, or protein nutrition in this experiment.

Characterization of the protein fraction of the temporary adhesive secreted by the tube feet of the sea star Asterias rubens.

Sea stars are able to make firm but temporary attachments to various substrata by secretions released by their tube feet. After tube foot detachment, the adhesive secretions remain on the substratum as a footprint. Proteins presumably play a key role in sea star adhesion, as evidenced by the removal of footprints from surfaces after a treatment with trypsin. However, until now, characterisation was hampered by their high insolubility. In this study, a non-hydrolytic method was used to render most of the proteins constituting the adhesive footprints soluble. After analysis by SDS-PAGE, the proteins separated into about 25 bands, which ranged from 25 to 450 kDa in apparent molecular weight. Using mass spectrometry and a homology-database search, it was shown that several of the proteins are known intracellular proteins, presumably resulting from contamination of footprint material with tube foot epidermal cells. However, 11 protein bands, comprising the most abundant proteins, were not identified and might correspond to novel adhesive proteins. They were named 'Sea star footprint proteins' (Sfps). Tandem mass spectrometry analysis of the protein bands yielded 43 de novo-generated peptide sequences. Most of them were shared by several, if not all, Sfps. Polyclonal antibodies were raised against one of the peptides (HEASGEYYR from Sfp-115) and were used in immunoblotting. They specifically labelled Sfp-115 and other bands with lower apparent molecular weights. The different results suggest that all Sfps might belong to a single family of related proteins sharing similar motifs or, alternatively, they are the products of polymerization and/or degradation processes.

Long-term environmental exposure to metals (Cu, Cd, Pb, Zn) activates the immune cell stress response in the common European sea star (Asterias rubens).

The common sea star Asterias rubens represents a key-species of the North-Eastern Atlantic macro benthic community. The cells of their immune system, known as coelomocytes, are the first line of defence against environmental hazards. Here, we report the results of investigations on the immune cells response of sea stars exposed to marine environmental pollution for long periods. We show that levels of the heat shock cognate protein 70 (HSC70) in coelomocytes from A. rubens, which were collected during a field study in the SÇ¿rfjord (North Sea, SW coast of Norway) along a contamination gradient, are directly associated with the long-term accumulation of Cd, Cu heavy metals exclusively in the tegument. Conversely, Pb and Zn accumulation in the tegument did not relate to HSC70 levels and none of the metals were found accumulated in the pyloric coeca. In addition the coelomocytes from A. rubens, collected in high and low metal impacted stations were examined by a proteomic approach using two-dimensional electrophoresis (2DE). By comparison of the proteomic maps, we observed that 31 protein spots differed in their relative abundance, indicating a gene expression response to the metal mixture exposure. All together, our results confirm that the echinoderm immune cells are a suitable model for the assessment of long-term exposure to environmental pollution, moreover that the increased level of HSC70 can be considered a signal of an acquired tolerance within a large spectrum of protein profile changes occurring in response to metal contamination.

Ethylacetate fraction from Korean seaside starfish, Asterias amurensis, has an inhibitory effect on MMP-9 activity and expression and on migration behavior of TNF-α induced human aortic smooth muscle cells.

Atherosclerosis is accompanied by the proliferation of human aortic smooth muscle cells (HASMC) and their movement into the intima. Many reports have indicated the involvement of gelatinases (MMP-9 and MMP-2) in this pathogenesis. The ethylacetate fraction from starfish, Asterias amurensis (EFA), harvested from the Korean seaside has an inhibitory effect on MMP-9 and MMP-2 activities, as well as on the expression of MMP-9 in TNF-α induced HASMC in a dose-dependent manner. Also, EFA inhibits the migration of TNF-α induced HASMC in transwells containing gelatin coated plugs. EFA was not cytotoxic to HASMC over the range 0-1mg/ml. By Western-blot analysis, it was revealed that the phosphorylation of extracellular signal regulated kinase (ERK) in TNF-α induced cells was inhibited and nuclear factor kappa B (NF-κB) p65 levels in nuclear extracts were decreased by EFA treatment. In addition, ERK inhibitor (U0126) treated cells exhibited decreased MMP-9 activity in the zymographic assay. From these results, it was found that the gelatinolytic activity was regulated (1) by enzymatic inhibition of both MMP-9 and MMP-2, as well as (2) by the decreased production of MMP-9 via ERK pathways in EFA treated HASMCs. Taken together, it has been shown that EFA has a putative anti-atherosclerotic effect.

Structural determination of cerebrosides isolated from Asterias amurensis starfish eggs using high-energy collision-induced dissociation of sodium-adducted molecules.

Six cerebrosides were isolated from the eggs of the starfish Asterias amurensis using solvent extraction, silica gel column chromatography, and reversed-phase high-performance liquid chromatography. This study demonstrated that the structures of cerebrosides could be completely characterized, based on their sodium-adducted molecules, using fast atom bombardment (FAB) tandem mass spectrometry. The high-energy collision-induced dissociation of the sodium-adducted molecule, [M + Na](+), of each cerebroside molecular species generated abundant ions, providing information on the compositions of the 2-hydroxy fatty acids and long-chain sphingoid bases, as well as the sugar moiety polar head group. Each homologous ion series along the fatty acid and aliphatic chain of the sphingoid base was useful for locating the double-bond positions of both chains and the methyl branching position of the long-chain base. The N-fatty acyl portions were primarily long-chain saturated or monoenoic acids (C16 to C24) with an α-hydroxy group. The sphingoid long-chain base portions were aliphatic chains (C18 or C22) with two or three degrees of unsaturation and with or without methyl branching.

Novel conserved structural domains of acrosome reaction-inducing substance are widespread in invertebrates.

In the starfish Asterias amurensis, acrosome reaction inducing substance (ARIS) is the main factor responsible for allowing sperm to recognize the egg jelly and begin the acrosome reaction (AR). ARIS is a large proteoglycan-like molecule, and its pentasaccharide repeat, Fragment 1 (Fr. 1), is responsible for inducing AR. Here, we investigated the primary structure of ARIS for the first time in order to improve our understanding of its functionality. Electrophoretic analysis revealed that ARIS is a complex of three proteins, all of which are modified by the Fr. 1 sugar chain. Sequencing indicated that there are two novel, conserved domains in all three ARIS proteins: ARIS N-terminus (AR-N) and ARIS C-terminus (AR-C) domains. We also found that other echinoderms possess ARIS proteins that are capable of inducing the AR for homologous sperm, indicating that ARIS proteins may be a ubiquitous component for echinoderm fertilization. Moreover, we identified ARIS-like genes from Ctenophora to Protochordata.

Asterosaponins isolated from the starfish Asterias amurensis.

Three new asterosaponins 1-3 and four known saponins 4-7 have been isolated from the starfish Asterias amurensis LÜTKEN. By means of high magnetic field 1D- and 2D-NMR ((1)H-(1)H correlation spectroscopy (COSY), total correlation spectroscopy (TOCSY), heteronuclear multiple quantum coherence (HMQC), heteronuclear single quantum coherence (HSQC), heteronuclear multiple bond correlation (HMBC), and nuclear Overhauser effect spectroscopy (NOESY)) and MS analyses, the chemical structures of new compounds were determined to be 6α-O-[ß-D-fucopyranosyl-(1→2)-ß-D-galactopyranosyl-(1→4)-[ß-D-quinovopyranosyl-(1→2)]-ß-D-quinovopyranosyl-(1→3)-ß-D-galactopyranosyl]-5α-chol-9(11)-en-23-one-3ß-yl sodium sulfate (1), 6α-O-[ß-D-fucopyranosyl-(1→2)-ß-D-galactopyranosyl-(1→4)-[ß-D-quinovopyranosyl-(1→2)]-ß-D-quinovopyranosyl-(1→3)-ß-D-galactopyranosyl]-5α-cholesta-9(11),24-dien-23-one-3ß-yl sodium sulfate (2), and 6α-O-[ß-D-fucopyranosyl-(1→2)-ß-D-galactopyranosyl-(1→4)-[ß-D-quinovopyranosyl-(1→2)]-ß-D-quinovopyranosyl-(1→3)-ß-D-galactopyranosyl]-5α-cholest-9(11)-en-23-one-3ß-yl sodium sulfate (3). In addition, the NMR data for known saponins 4-7 were completely assigned by extensive 2D-NMR analysis without chemical degradation.

[Effect of excretion-secretion products of some fouling species on the biochemical parameters of blue mussel Mytilus edulis L. (Mollusca: Bivalvia) in the White Sea].

The effect of excretion-secretion products (ESP) of five abundant fouling invertebrate species (bivalve mollusks Hiatella arctica and Mytilus edulis, solitary ascidia Styela rustica, sponge Halichondria panicea, and sea starAsterias rubens, inhabiting the White Sea) on the biochemical status of blue mussel M. edulis was assessed by the dynamics of lysosomal enzymes activity (nucleases, glycoside hydrolases, and cathepsins). ESP of conspecific species had no effect on the metabolism of the mollusks of this species. ESP of A. rubens, S. rustica, and H. panicea activated the same enzymes. First, acid RNase and glycoside hydrolases activity increased, but in different ways. The metabolites of H. arctica affected the activity of proteometabolism enzymes.

Acrosome reaction-related steroidal saponin, Co-ARIS, from the starfish induces structural changes in microdomains.

Cofactor for acrosome reaction-inducing substance (Co-ARIS) is a steroidal saponin from the starfish Asterias amurensis. Saponins exist in many plants and few animals as self-defensive chemicals, but Co-ARIS has been identified as a cofactor for inducing the acrosome reaction (AR). In A. amurensis, the AR is induced by the cooperative action of egg coat components (ARIS, Co-ARIS, and asterosap); however, the mechanism of action of Co-ARIS is obscure. In this study we elucidated the membrane dynamics involved in the action of Co-ARIS. We found that cholesterol specifically inhibited the Co-ARIS activity for AR induction and detected the binding of labeled compounds with sperm using radioisotope-labeled Co-ARIS. Co-ARIS treatment did not reduce the content of sperm sterols, however, the condition was changed and localization of GM1 ganglioside on the periacrosomal region disappeared. We then developed a caveola-breaking assay, a novel method to detect the effect of chemicals on microdomains of culture cell, and confirmed the disturbance of somatic cell caveolae in the presence of Co-ARIS. Finally, by atomic force microscopy observations and surface plasmon resonance measurements using an artificial membrane, we revealed that Co-ARIS colocalized with GM1 clusters on the microdomains. Through this study, we revealed a capacitation-like event for AR in starfish sperm.

[Extracts of mucopolysaccharides from Asterias rollestoni and its immunoregulation effect in vitro].

OBJECTIVE: To study immunoregulation effects on normal pulpal cells of the mucopolysaccharides MP1 and MP2 extracted from Asterias rollestoni body wall and viscera, respectively. METHODS: The orthogonal design was employed to obtain the best possible combination of the critical parameters for mucopolysaccharide MP2. MP1, MP2, glycosides, MP1 + glycosides and MP2 + glycosides were added respectively into pulpal cells culture media to test their effects on spleen cells proliferations by MTT assay. RESULTS: MP1 and MP2 could certainly increase the proliferation of the normal splenocyte and inhibit glycosides cytotoxicity. Compared with controls, MP2 reversed the cytotoxicity of glycosides at concentration of 25 to 40 mg/mL, the greatest activity appearing at the dose of 40 mg/mL (P<0.01), while MP1 didn't reverse it. CONCLUSION: MP1 and MP2 can enhance immunity of normal mice, and MP2 can significantly reverses the cytotoxicity of glycosides in vitro.

Growth inhibition and induction of apoptosis of colon cancer cell lines by applying marine phospholipid.

Polyunsaturated fatty acids (PUFAs) exhibit beneficial biological functions in carcinogenic processes. We examined the effects of PUFAs in the acid and phospholipid forms on three colon cancer cell lines (HT-29, Caco-2, and DLD-1). Docosahexaenoic acid (DHA) and eicosapentaenoic (EPA) in both acid and phospholipid forms showed growth inhibition effects on experimental colon cancer cell lines. But these PUFAs had the strongest growth-inhibitory effect on HT-29 than Caco-2 and DLD-1. Combined application of PUFAs and sodium butyrate (NaBt) increased the growth inhibition. Growth inhibition was apparently caused by increased lipid peroxidation. DHA or EPA in combination with NaBt significantly increased caspase-3 activity compared to control. DHA and DHA-rich phosphatidylcholine decreased Bcl-2 level in HT-29 and Caco-2 cells.

[The dependence of MMP-2 and MMP-9 activity in wound fluid on the wound tissue state at initial stages of wound healing process].

One of the problems in wound treatment optimization is the necessity of an effective and objective method of laboratory wound process monitoring. In present study the current wound process was estimated by changes in MMP-2 and MMP-9 activities in the wound fluid. An original model was used in this work to study correlation of morphological structure of the wound with the activities of MMP-2 and MMP-9 in wound fluid at various types of wound process. Protein fractions of the coelomic liquid from regenerating sea star Asterias rubens were used as the substances changing the wound process. The correlation of wound process with MMP-2 and MMP-9 activities in wound fluid was revealed on the basis of correlation analysis.

Glycosylceramides obtain from the starfish Asterias amurensis Lütken.

Complex lipids in the starfish Asterias amurensis were characterized and the influence of sphingoid bases on human colon carcinoma Caco-2 cells was also investigated. Lipid content of gonad and viscera were 3.3% and 6.8%, respectively, in wet basis. The main lipid class in gonad was ceramide monohexoside (CMH) while triglyceride (TG) was predominant in the viscera. The most abundant fatty acid in the polar lipid was eicosapentaenoic acid (EPA, C20:5n-3), with the gonad and viscera samples having the highest proportion of 41.5% and 32.7%, respectively, of total fatty acids. Starfish internal organ contained enormous amount (0.7% in wet base) of glycosylceramide. Sphingoid bases of the glycosylceramide were mainly consisted of d22:2, d22:1 and d18:3. This sphingoid base exerted an apoptotic activity on Caco-2 cells. Thus, starfish could be used as a potential source of precious and useful complex lipids.