Fucosylated chondroitin sulfate from sea cucumber Stichopus chloronotus alleviate the intestinal barrier injury and oxidative stress damage in vitro and in vivo.

This study aimed to investigate the alleviative effects of fucosylated chondroitin sulfate from sea cucumber Stichopus chloronotus (fCSSc) on the intestinal barrier injury and oxidative stress damage in vitro and in vivo. The results showed that fCS-Sc protected the intestinal barrier and improved the antioxidant function in H2O2 damaged Caco-2 cells via up-regulating the tight junction proteins and activating Keap1-Nrf2-ARE antioxidant pathway. Furthermore, administration fCS-Sc could ameliorate the weight loss and spleen index decrease in Cyclophosphamide (Cy) treated mice, improve the expressions of ZO-1, Claudin-1, Nrf2, SOD, and NQO-1 in Cy damaged colon tissue, showing significant protective effects against intestinal barrier damage and oxidative stress in vivo. fCS-Sc intervention also alleviated the gut microbiota disorder though increasing the richness and diversity of intestinal bacteria, regulating the structural composition of gut microbiota. fCS-Sc promoted the relative abundance of beneficial microbiota and inhibited the growth of harmful bacteria. This study provided a theoretical basis for the application of fCS-Sc as a prebiotic in chemotherapy.

The activation effects of fucoidan from sea cucumber Stichopus chloronotus on RAW264.7 cells via TLR2/4-NF-κB pathway and its structure-activity relationship.

Sea cucumber Stichopus chloronotus is a traditional tonic food with high nutritive value in Southern China. Fucoidan from sea cucumber Stichopus chloronotus (Fuc-Sc) is its main bio-active polysaccharide, the immune-activation effects of which have been fully investigated on RAW264.7 cells in the present study. The results indicated that Fuc-Sc could stimulate the RAW264.7 cells by promoting the production of NO, TNF-α, IL-6 and IL-10. Western blot and RT-PCR analysis revealed that TLR4 and TLR2 were involved in the recognition of Fuc-Sc and activation of downstream NF-κB signal pathway. Moreover, the chemical structure parameter molecular weight showed obvious impact on the stimulation effects of Fuc-Sc on NO production. Degraded product of Fuc-Sc with weight average molecular weight of 113.1 × 104 Da exhibited higher activities than that of intact Fuc-Sc, suggesting the existent of optimum chain length to exert its highest activities. Taken together, Fuc-Sc exerted its immunostimulating activity via TLR2/4 activation of NF-κB pathway and showed potentials to be a good immunoadjuvant.

Immunomodulatory effects of fucosylated chondroitin sulfate from Stichopus chloronotus on RAW 264.7 cells.

Sea cucumbers were nutritional food and traditional Chinese medicine. In this study, fucosylated chondroitin sulfate from sea cucumber Stichopus chloronotus (fCS-Sc), a potential anticoagulant agent and immunological adjuvant, was investigated for its immune activation effects on RAW 264.7 macrophage for the first time. The results indicated that fCS-Sc could significantly promote the proliferation, the pinocytic activity of RAW 264.7 cells, and the production of NO, TNF-α, IL-1ß, and IL-6. The fluorescence labeling assay indicated that fCS-Sc could bind to the macrophage. Moreover, the specific pattern recognition receptor inhibition assays showed that toll-like receptor 4 (TLR4) and TLR2 were involved in the recognition of fCS-Sc. Western blot assays indicated that fCS-Sc could induce degradation of cytoplasm IκB-α, and promotion of NF-κB p65 subunit translocation to nucleus, leading to a functional improvement of macrophage through NF-κB pathway. The results suggested that fCS-Sc might served as a promising candidate of immunomodulator.

Structure characterization, antioxidant and immunoregulatory properties of a novel fucoidan from the sea cucumber Stichopus chloronotus.

The detailed chemical structure and chain conformation of a novel fucoidan from the sea cucumber Stichopus chloronotus (Fuc-Sc) were investigated by HPLC, IR, NMR spectroscopy and multi-angle light scattering. It mainly consisted of l-fucose and sulfate esters at mole ratio of 1.0:1.3 and contained a →3)-α-l-fucose-2S-(1→ linear backbone. Besides, the chain conformation parameters αη (0.658 ± 0.001) and αh (0.612 ± 0.002) indicated that Fuc-Sc exhibited a random coil conformation in PBS. The worm-like cylinder model parameters ML (526 g/mol•nm) and q (6.9 nm) confirmed that Fuc-Sc adopted a flexible chain. Fuc-Sc possessed negative charges and good thermal stability. Moreover, Fuc-Sc showed significant inhibition of lipid peroxidation and obvious activation effects on RAW 264.7 cells by promoting their proliferation and the production of NO and TNF-α. The present study facilitated further understanding of the structure-activity relationship of Fuc-Sc and its application in food and pharmacy industries.

Chain conformation, physicochemical properties of fucosylated chondroitin sulfate from sea cucumber Stichopus chloronotus and its in vitro fermentation by human gut microbiota.

This study investigated the chain conformation, physicochemical properties of fucosylated chondroitin sulfate from Stichopus chloronotus (fCS-Sc) using HPSEC-MALLS and worm-like cylinder model methods and its impact on human gut microbiota by 16s RNA gene sequencing. The results indicated that fCS-Sc adopted rigid rods chain conformation in PBS based on chain conformational parameters αη (1.11) and αh (0.70). Stiffness parameters deduced from worm-like cylinder model suggested that fCS-Sc exhibited as stiff chains. The congo red assay indicated a single-helical structure. fCS-Sc demonstrated a negative zeta-potentials in a wide pH ranges and good thermal stability. Besides, fCS-Sc could modulate the community structure of gut microbiota by elevating the absolute abundance of microbiota, increasing the beneficial bacterium Megamonas, Bacteroides, Fusobacterium, Parabacteroides, Prevotella, Faecalibacterium, suppressing pathogenic microorganism and promoting the short-chain fatty acids production. The present studies improved the understanding of the spatial structures of fCSs and its application as prebiotics.

Comparison of chain conformation properties of bio-active fucosylated chondroitin sulfates from two different sea cucumbers.

The present studies aimed to investigate the chain conformation of fucosylated chondroitin sulfates from two different sea cucumbers Apostichopus japonicus (fCS-Aj), and Holothuria mexicana (fCS-Hm). The chain conformations were determined by SEC-MALLS-Visc-RI, indicating that the chain conformations of fCS-Aj and fCS-Hm were random coil and extended linear chain structure in PBS, respectively. Our results suggested that the formation of linear chain of fCS were due to a synergistic effect of molecular weight, sulfate content and sulfation patterns. The worm-like cylinder model indicated that fCS-Aj possessed more flexible chains compared with fCS-Hm. fCS-Aj and fCS-Hm all exhibited as negatively charged polymers with good thermal stability. The present studies were important for understanding the structure-activities relationship of fCSs.

Polyanionic holothurian glycosaminoglycans-doxorubicin nanocomplex as a delivery system for anticancer drugs.

A nanoscale delivery system for the anticancer drug doxorubicin (DOX) by complexation with depolymerized polyanionic holothurian glycosaminoglycans (DHG) was designed in the present studies. The physicochemical properties of the nanocomplexes were investigated by dynamic light scattering, transmission electron microscopy and zeta potential determination. DHG-DOX interaction was investigated in the presence of ethanol as a hydrogen-bond disrupting agent and NaCl as an electrostatic shielding agent. The thermal properties of nanocomplexes were ascertained by thermogravimetric analysis (TGA). The in vitro release profile was studied as well. Complexation of DHG and DOX formed spherical and smooth nanocomplexes with negative zeta potential (-46.3 mV) at a DHG/DOX (w/w) ratio of 1.0, where drug encapsulation efficiency was over 60%. The results indicated that the electrostatic and hydrogen bonds played an important role in DHG-DOX complexation. TGA confirmed that the nanocomplexes involved in the DHG as the as the coat and DOX as the content. The release profile of the nanocomplexes exhibited an initial fast release and an subsequent slow and sustained release. Furthermore, the in vitro cell cytotoxicity assays exhibited that the DOX loaded nanocomplexes could improve the cell killing ability of DOX for HepG-2, MCF-7 and A549 tumor cells and exert a sustained-release efforts in the cells.

Structural comparison, antioxidant and anti-inflammatory properties of fucosylated chondroitin sulfate of three edible sea cucumbers.

Three fucosylated chondroitin sulfate (fCS) were obtained from edible sea cucumbers Apostichopus japonicus, Stichopus chloronotus and Acaudina molpadioidea collected from China. fCS from Stichopus chloronotus was firstly reported. The detailed structures of fCSs, particularly the fucose branches, were investigated and compared. 1H and 13C NMR of the polysaccharide identified three sulfation patterns of fucose branches: 4-O-, 2,4-di-O, and 3,4-di-O-sulfation variously existed in different fCSs. The backbone structure was confirmed by the monosaccharide composition and two-dimensional NMR. Antioxidant properties of fCSs were evaluated by the scavenging abilities on 1,1-diphenyl-2-picrylhydrazyl, nitric oxide radicals and inhibition of lipid peroxidation. The results showed that their activities could be affected by the sulfation patterns of the fucose branches, and O-4 sulfation is particularly important for its activities. The anti-inflammatory assays of fCS-Am showed significant reduction of the carrageenan induced edema in a dose depended manner, which could be used as a potential antiallergic agent.

Preparation and antioxidant properties of low molecular holothurian glycosaminoglycans by H2O2/ascorbic acid degradation.

An effective method of free radical degradation induced by H2O2/ascorbic acid, which was different from previously reported H2O2/Cu2+ method, was developed to depolymerize a novel glycosaminoglycan from Holothuria mexicana (HmG). The results indicated that the degradation efficiency increased with the reduced solution concentration, increased H2O2 concentration and ascorbic acid concentration. The chemical composition and structure of different molecular HmG were analyzed. The results showed that the primary structure and sulfate esters were well reserved during the degradation. Two dimension nuclear magnetic resonance of a low molecular product (DHmG-2) indicate that it contained chondroitin sulfate backbone and major 4-O-sulfated fucose branches. The antioxidant assays of HmG and DHmG-3 showed a fine scavenging abilities on 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide and hydroxyl radicals in concentration dependent manner. Besides, molecular weight did not obviously affect the antioxidant activities of HmG.

Purification, structural characterization and anticoagulant properties of fucosylated chondroitin sulfate isolated from Holothuria mexicana.

A novel fucosylated chondroitin sulfate (HmG) was isolated from sea cucumber Holothuria mexicana, the structure of which was characterized by monosaccharide composition, disaccharide composition, IR, 1H and 13C NMR spectrum, additionally with two dimensional NMR spectrum of degraded HmG (DHmG). The backbone of HmG was identified as chondroitin 6-O sulfate, while the major O-4 sulfated fucose branches linked to O-3 position of glucuronic acid in almost every disaccharide unit. The anticoagulant activities of HmG and DHmG were assessed and compared with heparin and low molecular weight heparin. The results indicated that HmG and DHmG both could significantly prolong the activated partial thrombo-plastin time, and the properties were well related to its molecular weight. DHmG showed similar anticoagulant properties to low molecular weight heparin with less bleeding risks, making it a safer anticoagulant drug.

RETRACTED: In vivo and in vitro antithrombus activities of depolymerized holothurian polysaccharides.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of authors. The authors have recently found a serious mistake in Table 1 of the article, where the molecular ratio of different monosaccharides is inconsistent with their previously published work. This error flaws the paper and so the authors wish it to be retracted to avoid misunderstanding and misinterpretation of their research work. The authors apologise for any concern or confusion that might have resulted in publishing this article.