Macromolecular properties and hypolipidemic effects of four sulfated polysaccharides from sea cucumbers

Chain conformation and rheological properties of an acid-extracted polysaccharide from peanut sediment of aqueous extraction process

A polysaccharide (PPS) in peanut sediment of aqueous extraction process was obtained at pH4.0, purified via anion-exchange chromatography. The composition, chain conformation and rheological properties were investigated. PPS mainly consisted of arabinose, galacturonic acid, xylose, and rhamnose. The intrinsic viscosity [η] was 0.71 dL/g in 0.1 M NaNO₃ solution. The weight-average molar mass Mw and polydispersity index were 3.77 × 10⁵ g/mol and 1.25, suggesting high homogeneity. The average radius of gyration (R_g), hydrodynamic radius (R_h), R_g/R_h ratio and conformation parameter v were 25.5, 18.2, 1.40 and 0.21, respectively, indicating compact coil chain conformation with branched structure. Molecular morphology revealed that PPS displayed chain shape comprised of spheres with a diameter range of 15-50 nm and apparent length of chains mainly ranged from 100 to 300 nm. The aggregation caused by molecular self-association enhanced with concentration increasing. Additionally, Newtonian behavior was observed at various concentrations. Increase in temperature effectively broke this behavior. 10.0 wt.% PPS possessed activation energy of 21.7 KJ/mol, was structured liquid and almost fitted Cox-Merz rule. These closely related with its conformation and molecular self-association behavior.

Holothuria Leucospilota Polysaccharides Ameliorate Hyperlipidemia in High-Fat Diet-Induced Rats via Short-Chain Fatty Acids Production and Lipid Metabolism Regulation

Holothuria leucospilota polysaccharides (HLP) are expected to become potential resources for the treatment of hyperlipidemia because of their various bioactivities. In the study, the treatment of HLP on improving hyperlipidemia in rats was explored. Oral administration of HLP at 100 or 200 mg/kg body weight effectively alleviated serum lipid levels and liver histological abnormalities in high-fat-diet rats. HLP regulated abnormal mRNA, lipogenesis-related hormones and inflammatory cytokines (tumor necrosis factor-α, interleukin-6 and interleukin-12) levels. HLP improved the ability of gut microbiota to produce short-chain fatty acids (SCFAs). SCFAs have been found to ameliorate liver lesions. Therefore, HLP alleviated hyperlipidemia by improving the levels of SCFAs to regulate lipid metabolism. These results indicated that HLP could be used as beneficial polysaccharides to alleviate hyperlipidemia.

Structural Features and Digestive Behavior of Fucosylated Chondroitin Sulfate from Sea Cucumbers Stichopus japonicus

Fucosylated chondroitin sulfate from sea cucumber Stichopus japonicus (FCS_SJ) has been demonstrated with various biological activities; however, its precise structure is still controversial, and digestive behavior remains poorly understood. FCS_SJ was purified, and its detailed structure was elucidated mainly based on the NMR spectroscopic methods. Its main chain was characterized as →4)-β-d-GlcA-(1 → 3)-β-d-GalNAc-(1→ with GalNAc4S6S:GalNAc4S in a ratio of 1.5:1, and three types of sulfated fucosyl branches attaching C-3 of GlcA, namely, Fucp2S4S, Fucp3S4S, and Fucp4S, were found in a ratio of 2:1.5:1. The digestibility of FCS_SJ was investigated in vitro, and the unchanged molecular weight and reducing sugar content indicated that FCS_SJ was not broken down under salivary and gastrointestinal digestion. Furthermore, FCS_SJ showed a significant inhibitory impact on pancreatic lipase dose-dependently but not on α-amylase, indicating that the inhibition of pancreatic lipase by FCS_SJ might be a pathway for its hypolipidemic effect. These findings propose a fucosylated chondroitin sulfate and provide insight into the mechanism of its physiological effects in the digestion system.

Structure and molecular morphology of a novel moisturizing exopolysaccharide produced by Phyllobacterium sp. 921F

Bacterial exopolysaccharides (EPSs) are widely applied in food, cosmetic, and medical industries. The EPS produced by Phyllobacterium sp. 921F was a novel polysaccharide, which exhibits attractive characteristics of high yield, favorable rheological properties, and excellent moisture retention ability. Considering the complexity of polysaccharide structures, specific enzymatic hydrolysis was employed here to resolve the structure of the EPS. End-products including tetra-, hexa- and octa-saccharides were isolated. According to their mass spectroscopy (MS) and nuclear magnetic resonance (NMR) spectra, the backbone of the EPS was found to be mainly comprising a → 4)-β-d-Glcp-(1 → 3)-α-d-Galp(4,6-S-Pyr)-(1 → disaccharide repeating units. Based on atomic force microscopy results, EPS exhibited characteristics that were consistent with a stiff, elongated molecule with no branches. The length and height of the single molecular chain were approximately 600 and 0.7 nm, respectively. Our clarification of structure and molecular morphology of EPS from Phyllobacterium sp. 921F provide a foundation for the industrial application of this potential moisture-retaining material.

Characterization and anti-inflammatory effects of sulfated polysaccharide from the red seaweed Gelidium pacificum Okamura

In the present study, crude polysaccharides were extracted from Gelidium pacificum Okamura, and further purified to obtain the sulfated polysaccharide with molecular weight of 28,807 Da. Its monosaccharide composition mainly consisted of xylose (7.1%), galactose (59.7%) and galacturonic acid (19.76%). And the sulfate ester content of the sulfated polysaccharide was estimated as 8.8%. Structure analysis showed that the sulfated polysaccharide comprised of 1,4-linked-α-D-Galp3S, 1,2-linked-α-D-Xylp and 1,3-linked-β-D-GalpA residues, respectively. Its anti-inflammatory effects were investigated in LPS-stimulated human monocytic (THP-1) cells. The sulfated polysaccharide at a concentration of 5 μg/mL fully protected the THP-1 cells against LPS-stimulated cytotoxicity. Furthermore, the addition of sulfated polysaccharide resulted in a significant reduction of NO production in LPS-treated cells, and this effect appeared to be dose-related. The sulfated polysaccharide (5 μg/mL) significantly suppressed the mRNA and protein expression of toll-like receptor-4 (TLR-4), myeloid differentiation factor (MyD88) and tumor necrosis factor receptor-associated factor-6 (TRAF-6) in LPS-stimulated THP-1 cells. These results showed the sulfated polysaccharide not only provided a good protection against LPS-induced cell toxicity, but also exerted an anti-inflammatory effect via the TLR4 signaling pathway.

Ultrasound-assisted fast preparation of low molecular weight fucosylated chondroitin sulfate with antitumor activity

Fucosylated chondroitin sulfate from sea cucumber Isostichopus badionotus (fCS-Ib) was depolymerized with an ultrasound-accelerated, metal-free Fenton chemistry, relying on H₂O₂/ascorbic acid redox system. Fragments of different molecular weights were obtained at different reaction temperatures, ascorbic acid concentrations and ultrasonic intensities. The structures of two typical depolymerized fragments were evaluated using high-performance liquid chromatography (HPLC), infrared spectroscopy (IR), and nuclear magnetic resonance spectroscopy (NMR). The results showed that ultrasound enhanced the degradation efficiency of H₂O₂/ascorbic acid system mainly by disaggregating sulfated polysaccharide clusters and that free radicals induced depolymerization with no significant chemical changes in the backbone of fCS-Ib and with no obvious loss of fucose branches. The antitumor activity, using A549 lung cancer cells, showed that the ultrasound treated low molecular weight sulfated fragment enhanced proliferation-inhibitory and anti-migration effects, compared to native fCS-Ib. This was different from the anticoagulant activity of fCS-Ib, suggesting that the molecular weight change may cause a conformational transition and affect biological activity. We propose that combining ultrasound with non-metal Fenton chemistry as an effective method to prepare low molecular weight fCS fragments with potential applications as functional foods, antitumor drugs, and that these fCS fragments display negligible bleeding risk.

Structure and Anti-Inflammatory Activity of a New Unusual Fucosylated Chondroitin Sulfate from Cucumaria djakonovi

Fucosylated chondroitin sulfate CD was isolated from the sea cucumber Cucumaria djakonovi collected from the Avachinsky Gulf of the eastern coast of Kamchatka. Structural characterization of CD was performed using a series of non-destructive NMR spectroscopic procedures. The polysaccharide was shown to contain a chondroitin core [→3)-β-d-GalNAc-(1→4)-β-d-GlcA-(1→]n where about 60% of GlcA residues were 3-O-fucosylated, while another part of GlcA units did not contain any substituents. The presence of unsubstituted both at O-2 and O-3 glucuronic acid residues in a structure of holothurian chondroitin sulfate is unusual and has not been reported previously. Three different fucosyl branches Fucp2S4S, Fucp3S4S and Fucp4S were found in the ratio of 2:1:1. The GalNAc units were mono- or disulfated at positions 4 and 6. Anti-inflammatory activity of CD was assessed on a model of acute peritoneal inflammation in rats. About 45% inhibition was found for CD, while a structurally related linear chondroitin sulfate SS from cartilage of the fish Salmo salar demonstrated only 31% inhibition, indicating that the presence of sulfated fucosyl branches is essential for anti-inflammatory effect of chondroitin sulfates of marine origin.

Enzyme-Assisted Extraction Optimization, Characterization and Antioxidant Activity of Polysaccharides from Sea Cucumber Phyllophorus proteus

Enzyme-assisted extraction optimization, characterization and in vitro antioxidant activity of polysaccharides from sea cucumber Phyllophorus proteus (PPP) were investigated in the present study. The optimal extraction conditions with a yield of 6.44 ± 0.06% for PPP were determined as follows: Extraction time of 2.89 h, ratio of extraction solvent to raw material of 16.26 mL/g, extraction pH of 6.83, exraction temperature of 50 °C and papain concentration of 0.15%. Three purified fractions, PPP-1a, PPP-1b and PPP-2 with molecular weights of 369.60, 41.73 and 57.76 kDa, respectively, were obtained from PPP by chromatography of FPA98Cl and Sepharose CL-6B columns. Analysis of monosaccharide compositions showed that PPP-1a consisted of N-acetyl-galactosamine (GalNAc), galactose (Gal) and fucose (Fuc), PPP-1b of Fuc as the only monosaccharide and PPP-2 of glucuronic acid, GalNAc and Fuc. Sulfate contents of PPP, PPP-1a, PPP-1b and PPP-2 were determined to be 21.9%, 20.6%, 25.2% and 28.0% (w/w), respectively. PPP and PPP-1a had higher molecular weight and intrinsic viscosity than those of the PPP-1b and PPP-2. PPP, PPP-1a, PPP-1b and PPP-2 exhibited obvious activities of scavenging 1,1-diphenyl-2-picrylhydrazyl radical, hydroxyl radical, superoxide radical and ABTS radical in different extent, which suggested that the polysaccharides from Phyllophorus proteus may be novel agents having potential value for antioxidation.

Structural elucidation of fucosylated chondroitin sulfates from sea cucumber using FTICR-MS/MS

Fucosylated chondroitin sulfates are complex polysaccharides extracted from sea cucumber. They have been extensively studied for their anticoagulant properties and have been implicated in other biological activities. While nuclear magnetic resonance spectroscopy has been used to extensively characterize fucosylated chondroitin sulfate oligomers, we herein report the first detailed mass characterization of fucosylated chondroitin sulfate using high-resolution Fourier transform ion cyclotron resonance mass spectrometry. The two species of fucosylated chondroitin sulfates considered for this work include Pearsonothuria graeffei (FCS-Pg) and Isostichopus badionotus (FCS-Ib). Fucosylated chondroitin sulfate oligosaccharides were prepared by N-deacetylation-deaminative cleavage of the two fucosylated chondroitin sulfates and purified by repeated gel filtration. Accurate mass measurements obtained from electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry measurements confirmed the oligomeric nature of these two fucosylated chondroitin sulfate oligosaccharides with each trisaccharide repeating unit averaging four sulfates per trisaccharide. Collision-induced dissociation of efficiently deprotonated molecular ions through Na/H+ exchange proved useful in providing structurally relevant glycosidic and cross-ring product ions, capable of assigning the sulfate modifications on the fucosylated chondroitin sulfate oligomers. Careful examination of the tandem mass spectrometry of both species deferring in the positions of sulfate groups on the fucose residue (FCS-Pg-3,4- OS) and (FCS-Ib-2,4- OS) revealed cross-ring products 0,2Aαf and 2,4X2αf which were diagnostic for (FCS-Pg-3,4- OS) and 0,2X2αf diagnostic for (FCS-Ib-2,4- OS). Mass spectrometry and tandem mass spectrometry data acquired for both species varying in oligomer length (dp3-dp15) are presented.

A fucoidan from sea cucumber Pearsonothuria graeffei with well-repeated structure alleviates gut microbiota dysbiosis and metabolic syndromes in HFD-fed mice

A high-fat diet (HFD) has been a major contributor to increasing morbidity caused by metabolic syndromes.