Gastric Protective Activities of Sea Cucumber Fucoidans with Different Molecular Weight and Chain Conformations: A Structure-Activity Relationship Investigation

A comprehensive review of sulfated fucan from sea cucumber: Antecedent and prospect

Sulfated fucan from sea cucumber is mainly consists of L-fucose and sulfate groups. Recent studies have confirmed that the structure of sulfated fucan mainly consists of repeating units, typically tetrasaccharides. However, there is growing evidence indicating the presence of irregular domains with heterogeneous units that have not been extensively explored. Moreover, as a key contributor to the nutritional benefits of sea cucumbers, sulfated fucan demonstrates a range of biological activities, such as anti-inflammatory, anticancer, hypolipidemic, anti-hyperglycemic, antioxidant, and anticoagulant properties. These biological activities are profoundly influenced by the structural features of sulfated fucan including molecular weight and distribution patterns of sulfate groups. The latest research indicates that sulfated fucan is dispersed in the extracellular matrix of the body wall of sea cucumbers. This article aimed to review the research progress on the in-situ distribution, structures, structural elucidation strategies, functions, and structure-activity relationships of sulfated fucan, especially in the last decade. It also provided insights into the major challenges and potential solutions in the research and development of sulfated fucan. Moreover, the fucanase and carbohydrate binding modules are anticipated to play pivotal roles in advancing this field.

Exploring the Underlying Mechanisms of Preventive Treatment Related to Dietary Factors for Gastric Diseases

Gastric diseases have emerged as one of the main chronic diseases in humans, leading to considerable health, social, and economic burdens. As a result, using food or "food and medicinal homologous substances" has become an effective strategy to prevent gastric diseases. Diet may play a crucial role in the prevention and mitigation of gastric diseases, particularly long-term and regular intake of specific dietary components that have a protective effect on the stomach. These key components, extracted from food, include polysaccharides, alkaloids, terpenoids, polyphenols, peptides, probiotics, etc. The related mechanisms involve regulating gastric acid secretion, protecting gastric mucosa, increasing the release of gastric defense factors, decreasing the level of inflammatory factors, inhibiting Helicobacter pylori infection, producing antioxidant effects or reducing oxidative damage, preventing gastric oxidative stress by inhibiting lipid peroxides, activating Nrf2 signaling pathway, and inhibiting NF-κB, TLR4, and NOS/NO signaling pathways.

Biochemical characterization and cleavage specificities analyses of three endo-1,3-fucanases within glycoside hydrolase family 174

Sulfated fucans have garnered extensive research interest in recent decades due to their varied bioactivity. Fucanases are important tools for investigating sulfated fucans. This study reported the bioinformatic analysis and biochemical properties of three GH174 family endo-1,3-fucanases. Wherein, Fun174Rm and Fun174Sb showed the highest optimal reaction temperature among the reported fucanases, and Fun174Sb possessed favorable thermostability and catalysis efficiency. Fun174Rm displayed a random endo-acting manner, while Fun174Ri and Fun174Sb hydrolyzed sulfated fucan in processive manners. UPLC-MS and NMR analyses confirmed that the three enzymes catalyze cleavage of the α(1 → 3)-bonds between Fucp2S and Fucp2S in the sulfated fucan from Isostichopus badionotus. These enzymes demonstrated novel cleavage specificities, which could accept α-Fucp2S residues at subsites -1 and + 1. The acquiring of these biotechnological tools would be beneficial to the in-depth research of sulfated fucans.

Structure characteristics, protective effect and mechanisms of ethanol-fractional polysaccharides from Dendrobium officinale on acute ethanol-induced gastritis

Gastritis is a common disease characterized by gastric ulcers and severe bleeding. Excessive daily alcohol consumption can cause acute gastritis, impacting individuals' quality of life. This study aims to explore the protective effects of different ethanol-fractional polysaccharides of Dendrobium officinale (EPDO) on acute alcohol-induced gastric injury in vivo. Results showed that EPDO-80, identified as a β-glucan, exhibited significant anti-inflammatory properties in pathology. It could reduce the area of gastric mucosal injury and cell infiltration. EPDO-80 had a dose-effect relationship in reducing the levels of malondialdehyde and cyclooxygenase-2 and decreasing the levels of inflammation mediators such as tumor necrosis factor α. More extensively, EPDO-80 could inhibit the activation of the TNFR/IκB/NF-κB signaling pathway, reducing the production of TNF-α mRNA and cell apoptosis in organs. Conversely, EPDO-80 could promote changes in the gut microbiota structure. These findings suggest that EPDO-80 could have great potential in limiting oxidative stress and inflammation mediated by inhibiting the NF-κB signaling pathway, which is highly related to its β-glucan structure and functions in gut microbiota.

Comparative study on chain conformations, physicochemical and rheological properties of three acidic polysaccharides from Opuntia dillenii Haw. fruits

In this study, three acidic polysaccharides (OFPP-1, OFPP-2 and OFPP-3) were isolated from the pulps of Opuntia dillenii Haw. fruits, and their chain conformations, physicochemical and rheological properties were investigated. The molecular weight and conformational parameters (Mw, Mn, Mz, Rg and Rh) of OFPPs in 0.1 M NaNO3 solution were detected by HPSEC-MALLS-RI. In addition, based on the parameters ρ and v, it was concluded that these three polysaccharide chains exhibited sphere-like conformation in 0.1 M NaNO3 solution, which was consistent with AFM and TEM observations. Furthermore, the Congo Red experiment showed that OFPP-2 had a triple-helix structure, which may be conducive to its biological activity. This study also found that OFPPs were semi-crystalline structures with high thermal and pH stability. The rheological analyses indicated that the apparent viscosity of OFPPs solutions exhibited concentration-, temperature-, and pH-dependence, and the viscoelasticity of them was affected by molecular characteristics and concentration. The results of this study are helpful to elucidate the structure-activity relationship of OFPPs. Moreover, this study can provide theoretical reference for the application of OFPPs as bioactive ingredients or functional materials in the food, pharmaceutical and cosmetic industries and the development and utilization of the O. dillenii Haw. fruits resource.

The molecular mechanism of polysaccharides in combating major depressive disorder: A comprehensive review

Major depressive disorder (MDD) is a complex psychiatric condition with diverse etiological factors. Typical pathological features include decreased cerebral cortex, subcortical structures, and grey matter volumes, as well as monoamine transmitter dysregulation. Although medications exist to treat MDD, unmet needs persist due to limited efficacy, induced side effects, and relapse upon drug withdrawal. Polysaccharides offer promising new therapies for MDD, demonstrating antidepressant effects with minimal side effects and multiple targets. These include neurotransmitter, neurotrophin, neuroinflammation, hypothalamic-pituitary-adrenal axis, mitochondrial function, oxidative stress, and intestinal flora regulation. This review explores the latest advancements in understanding the pharmacological actions and mechanisms of polysaccharides in treating major depression. We discuss the impact of polysaccharides' diverse structures and properties on their pharmacological actions, aiming to inspire new research directions and facilitate the discovery of novel anti-depressive drugs.

Discovery of a catalytic domain defines a new glycoside hydrolase family containing endo-1,3-fucanase

Sulfated fucans are important marine polysaccharides with various bioactivities. Fucanases are desirable tools for the structural elucidations and oligosaccharides preparation of sulfated fucans. Herein, a gene with unknown function was screened from a sulfated fucan utilization locus in genome of marine bacterium Wenyingzhuangia aestuarii OF219 with the assistance of a machine learning approach on the structural biology. An undefined catalytic domain that presented in this gene was further cloned and expressed in Escherichia coli. Utilizing a sulfated fucan tetrasaccharide with definite structure as substrate, the endo-acting cleavage point of expressed protein (named Fun187A) was identified as the α-l-1,3-glycosidic bond between Fucp and Fucp(2OSO3-). Fun187A demonstrated a novel cleavage specificity, that is the subsite -1 could tolerate α-l-Fucp, and the subsite +1 could tolerate α-l-Fucp(2OSO3-). A homologue of Fun187A was also validated to display the endo-1,3-fucanse activity. The sequence novelty of Fun187A and its homologue defines a new glycoside hydrolase family, GH187.

A comparative investigation of anionic polysaccharides on the structure and gastrointestinal digestion of collagen fibrils

Collagen, the most abundant and widely distributed functional protein in mammals, typically assembles into collagen fibrils through side-by-side packing. The purpose of this study was to comparatively investigate the fate of sea cucumber collagen fibrils in the gastrointestinal tract when interacting with different anionic polysaccharides (fucoidan (FUC), Kappa-carrageenan (K-car), sodium alginate (SA)). Results revealed that the gel properties and viscosity values of collagen fibrils were notably enhanced, and the rate of structural alteration in collagen fibrils was reduced when K-car and SA were introduced. Conversely, in the presence of FUC, collagen fibril viscosity decreased, and the secondary structure of collagen fibrils underwent changes. FUC was found to diminish the structural stability of collagen fibrils and accelerate the gastric digestion rate, which was further exacerbated by thermal treatment. All these anionic polysaccharides were observed to facilitate the formation of collagen peptide aggregates by binding to polysaccharides during intestinal digestion. This study bridged the knowledge gap regarding the impact of anionic polysaccharides on the gastrointestinal digestion of collagen fibrils, potentially paving the way for broader applications of collagen in the food industry.

Characterization of a novel endo-1,3-fucanase from marine bacterium Wenyingzhuangia fucanilytica reveals the presence of diversity within glycoside hydrolase family 168

Sulfated fucans attract increasing research interests in recent decades for their various physiological activities. Fucanases are indispensable tools for the investigation of sulfated fucans. Herein, a novel GH168 family endo-1,3-fucanase was cloned from the genome of marine bacterium Wenyingzhuangia fucanilytica. The expressed protein Fun168D was a processive endo-acting enzyme. Ultra performance liquid chromatography-high resolution mass spectrum and NMR analyses revealed that the enzyme cleaved the α-1 → 3 bonds between α-l-Fucp(2OSO₃^-) and α-l-Fucp(2OSO₃^-) in sulfated fucan from Isostichopus badionotus, and α-1 → 3 bonds between α-l-Fucp(2OSO₃^-) and α-l-Fucp(2,4OSO₃^-) in sulfated fucan from Holothuria tubulosa. Fun168D would prefer to accept α-l-Fucp(2,4OSO₃^-) than α-l-Fucp(2OSO₃^-) at subsite +1, and could tolerate the absence of fucose residue at subsite +2. The novel cleavage specificity and hydrolysis pattern revealed the presence of diversity within the GH168 family, which would facilitate the development of diverse biotechnological tools for the molecule tailoring of sulfated fucan.

Chain conformation, mucoadhesive properties of fucoidan in the gastrointestinal tract and its effects on the gut microbiota

Fucoidans are valuable marine polysaccharides with various bioactivities and physicochemical properties. However, its digestive properties, mucoadhesive properties, and bioactivity in the gastrointestinal tract are still unclear. In this study, simulated digestion, fecal fermentation in vitro, and rheology models were utilized to investigate the chain conformation, influence on gut microbiota, and mucin adhesive properties of fucoidan from the sea cucumber Thelenota ananas (Ta-FUC). The results showed that Ta-FUC was nondigestible with a temporary decrease in molecular weight in gastric conditions, accompanied by the chain conformation becoming more flexible. Moreover, Ta-FUC exhibited strong mucin adhesive function in the simulated intestinal environment, with supramolecular disulfide, hydrogen, and hydrophobic interactions in order of intensity. During fermentation, Ta-FUC was degraded by the intestinal flora to produce various short-chain fatty acids and promoted the relative abundance of Bacteroidota and Firmicutes, reducing the proportion of Proteobacteria. Therefore, these results indicate that Ta-FUC could be a potential prebiotic and ingredient for developing targeted delivery systems in the functional food and pharmaceutical industries.

Extraction of high purity fucoidans from brown seaweeds using cellulases and alginate lyases

Fucoidans are fucose rich sulfated polysaccharides that are found in the cell wall of brown seaweeds and have been shown to have several beneficial bioactivities. In the present study, we report a new enzymatic extraction technique for the production of pure and intact fucoidans from the two brown seaweeds Saccharina latissima and Alaria esculenta. This new extraction protocol uses the commercial cellulase blend Cellic® CTec2 in combination with endo- and exo-acting thermophilic alginate lyases. The fucoidans obtained by this extraction technique are compared to traditionally extracted fucoidans in terms of chemical compositions and molecular weights and are shown to contain significantly higher amounts of fucose and sulfate, the main components of fucoidans, while cellulose, laminarin, and alginate contamination is low. Thus, by using this combination of enzymes, the extracted fucoidans do not undergo depolymerization during extraction and additional purification steps are not needed. The high purity fucoidans isolated by this new enzymatic extraction technique can be used to provide insight into the different fucoidan structures and biological activities.

A Natural Glucan from Black Bean Inhibits Cancer Cell Proliferation via PI3K-Akt and MAPK Pathway

A natural α-1,6-glucan named BBWPW was identified from black beans. Cell viability assay showed that BBWPW inhibited the proliferation of different cancer cells, especially HeLa cells. Flow cytometry analysis indicated that BBWPW suppressed the HeLa cell cycle in the G2/M phase. Consistently, RT-PCR experiments displayed that BBWPW significantly impacts the expression of four marker genes related to the G2/M phase, including p21, CDK1, Cyclin B1, and Survivin. To explore the molecular mechanism of BBWPW to induce cell cycle arrest, a transcriptome-based target inference approach was utilized to predict the potential upstream pathways of BBWPW and it was found that the PI3K-Akt and MAPK signal pathways had the potential to mediate the effects of BBWPW on the cell cycle. Further experimental tests confirmed that BBWPW increased the expression of BAD and AKT and decreased the expression of mTOR and MKK3. These results suggested that BBWPW could regulate the PI3K-Akt and MAPK pathways to induce cell cycle arrest and ultimately inhibit the proliferation of HeLa cells, providing the potential of the black bean glucan to be a natural anticancer drug.

Potential metabolites of Arecaceae family for the natural anti-osteoarthritis medicine: A review

Osteoarthritis (OA) is a chronic inflammatory disorder of the joints caused by fluid and cartilage matrix component reduction. This disease results in symptoms of pain, deformity, and limitation of movement. In general, OA is treated with anti-inflammatory drugs and chondroprotection compounds, includes natural nutraceutical ingredients, which are expected to be effective and have minimal side effects. Arecaceae plants are widely spread worldwide, especially in tropical areas. The objective of this review is to collect information about the Arecaceae family as anti-OA agents, with the main study focusing on the primary and secondary metabolites of plants of the Arecaceae family, i.e., sugar palm (Arenga pinnata), nipa palm (Nypa fruticans), palmyra palm (Borassus flabellifer), date palm (Phoenix dactylifera), and betel nut (Areca catechu) have potential as anti-OA agents. The Arecaceae's metabolites that show anti-inflammatory and chondroprotective effects are galactomannan, fatty acids (linoleic and linolenic acids), flavonoids (quercetin, luteolin, isorhamnetin), phenolics (coumaric acid, ferulic acid), polyphenols (epicatechin), and steroids (stigmasterol, campesterol, spirostane). Based on the reports, the Arecaceae family plants become worthy of being explored and developed into natural anti-OA products, such as supplements or nutraceuticals.

Fucoidan Ameliorated Dextran Sulfate Sodium-Induced Ulcerative Colitis by Modulating Gut Microbiota and Bile Acid Metabolism

Gut dysbiosis and bile acid (BA) metabolism disturbance are involved in the pathogenesis of ulcerative colitis. This study aimed to investigate the effect of fucoidan on BA metabolism and gut microbiota in dextran sulfate sodium-induced colitis mice. Our results showed that fucoidan effectively suppressed colonic inflammation and repaired the gut barrier. In addition, fucoidan increased the relative abundance of the Lachnospiraceae family, such as Turicibacter, Muribaculum, Parasutterella, and Colidextribacter, followed by an increase in short-chain fatty acids, especially in butyrate. Moreover, fucoidan modulated bile acid metabolism by elevating cholic acid, ursodeoxycholic acid, deoxycholic acid, and lithocholic acid and decreasing β-muricholic acid, which led to activation of FXR and TGR5 and further enhanced the gut barrier and suppressed colonic inflammation. Our results revealed that the effect of fucoidan alleviating colitis was largely mediated by gut microbiota, which was confirmed by the fecal transplantation experiment. Collectively, these findings provided the basis for fucoidan as a potential functional food for colitis.

Anti-Inflammatory Effects of Compounds from Echinoderms

Chronic inflammation can extensively burden a healthcare system. Several synthetic anti-inflammatory drugs are currently available in clinical practice, but each has its own side effect profile. The planet is gifted with vast and diverse oceans, which provide a treasure of bioactive compounds, the chemical structures of which may provide valuable pharmaceutical agents. Marine organisms contain a variety of bioactive compounds, some of which have anti-inflammatory activity and have received considerable attention from the scientific community for the development of anti-inflammatory drugs. This review describes such bioactive compounds, as well as crude extracts (published during 2010-2022) from echinoderms: namely, sea cucumbers, sea urchins, and starfish. Moreover, we also include their chemical structures, evaluation models, and anti-inflammatory activities, including the molecular mechanism(s) of these compounds. This paper also highlights the potential applications of those marine-derived compounds in the pharmaceutical industry to develop leads for the clinical pipeline. In conclusion, this review can serve as a well-documented reference for the research progress on the development of potential anti-inflammatory drugs from echinoderms against various chronic inflammatory conditions.

Sea cucumber-derived compounds for treatment of dyslipidemia: A review

Dyslipidemias are disorders of plasma levels of lipids, such as elevated levels of total cholesterol and triglyceride, that are associated with various human diseases including cardiovascular disease (CVD) and non-alcoholic fatty liver disease (NAFLD). Statins are the first-line drugs for treatment of dyslipidemia. However, a substantial proportion of patients cannot reach the recommended LDL-c level even with the highest tolerated doses of statins, and there is no available drug specifically for NAFLD therapy. Sea cucumbers are one of the widely distributed invertebrates, and are an important resource of food and medicine. Sea cucumbers have many valuable nutrients including saponins, fatty acids, phospholipids, cerebrosides, sulfated polysaccharides, as well as proteins and peptides. In recent years, these natural products derived from sea cucumbers have attracted attentions for treatment of CVD and NAFLD because of their lipid-lowering effect and low toxicity. However, the hypolipidemic mechanisms of action and the structure-activity relationship of these bioactive components have not been well-documented in literature. This review article summarizes the signaling pathways and the potential structure-activity relationship of sea cucumber-derived bioactive compounds including saponins, lipids, carbohydrates as well as peptides and proteins. This article will provide information useful for the development of sea cucumber-derived lipid-lowering compounds as well as for investigation of hypolipidemic compounds that are derived from other natural resources.

Structural characterization and protective effects of polysaccharide from Gracilaria lemaneiformis on LPS-induced injury in IEC-6 cells

This study was aimed to characterize Gracilaria lemaneiformis polysaccharides and evaluate their protective effects on Lipopolysaccharide-induced injury in IEC-6 cells. The G. lemaneiformis polysaccharide was degraded by UV/H₂O₂ treatment and purified to three fractions named GLP-1.0 M, GLP-1.4 M and GLP-1.6 M. The purified fractions were mainly composed of galactose, glucose and xylose. The structural analysis showed that GLP-1.6 M was a typical sulfated red alga polysaccharide containing the linear backbone of β-(1 → 3)- and α-(1 → 4)-linked galactosyl residues, anhydro-galactose units. In the Lipopolysaccharide-induced IEC-6 cells model, GLP-1.6 M exerted the strongest in vitro anti-inflammatory activity by inhibiting the release and expressions of tumor necrosis factor-α, interleukin-6 and interleukin-1β by 89.93%, 67.82% and 38.06%, respectively. Meanwhile, GLP-1.6 M enhanced the intestinal barrier function via up-regulating the expressions of tight junctions and mucin. Therefore, the purified polysaccharide from G. lemaneiformis could be a promising candidate for maintaining intestinal health in the food and pharmaceutical industries.

Low Molecular Weight, 4-O-Sulfation, and Sulfation at Meta-Fucose Positively Promote the Activities of Sea Cucumber Fucoidans on Improving Insulin Resistance in HFD-Fed Mice

Fucoidans from sea cucumber (SC-FUC) have been proven to alleviate insulin resistance in several species. However, there are few studies that clarify the relationship between their structure and bioactivity. The present study evaluated the influence of molecular weight (Mw), sulfation concentrations (Cs), and sulfation position on improving insulin resistance using SC-FUC. Results showed that fucoidans with lower Mw exerted stronger effects. Having a similar Mw, Acaudina molpadioides fucoidans (Am-FUC) with lower Cs and Holothuria tubulosa fucoidans with higher Cs showed similar activities. However, Isostichopus badionotus fucoidans (higher Cs) activity was superior to that of low-Mw Thelenota ananas fucoidans (Ta-LFUC, lower Cs). Eliminating the effects of Mw and Cs, the bioactivity of Am-FUC with sulfation at meta-fucose exceeded that of Ta-FUC with sulfation at ortho-position. Moreover, the effects of Pearsonothuria graeffei fucoidans with 4-O-sulfation were superior to those of Am-LFUC with 2-O-sulfation. These data indicate that low Mw, 4-O-sulfation, and sulfation at meta-fucose contributed considerably to insulin resistance alleviation by SC-FUC, which could accelerate the development of SC-FUC as a potential food supplement to alleviate insulin resistance.

The vicK gene of Streptococcus mutans mediates its cariogenicity via exopolysaccharides metabolism

Streptococcus mutans (S. mutans) is generally regarded as a major contributor to dental caries because of its ability to synthesize extracellular polysaccharides (EPS) that aid in the formation of plaque biofilm. The VicRKX system of S. mutans plays an important role in biofilm formation. The aim of this study was to investigate the effects of vicK gene on specific characteristics of EPS in S. mutans biofilm. We constructed single-species biofilms formed by different mutants of vicK gene. Production and distribution of EPS were detected through atomic force microscopy, scanning electron microscopy and confocal laser scanning microscopy. Microcosmic structures of EPS were analyzed by gel permeation chromatography and gas chromatography-mass spectrometry. Cariogenicity of the vicK mutant was assessed in a specific pathogen-free rat model. Transcriptional levels of cariogenicity-associated genes were confirmed by quantitative real-time polymerase chain reaction. The results showed that deletion of vicK gene suppressed biofilm formation as well as EPS production, and EPS were synthesized mostly around the cells. Molecular weight and monosaccharide components underwent evident alterations. Biofilms formed in vivo were sparse and contributed a decreased degree of caries. Moreover, expressional levels of genes related to EPS synthesis were down-regulated, except for gtfB. Our report demonstrates that vicK gene enhances biofilm formation and subsequent caries development. And this may due to its regulations on EPS metabolism, like synthesis or microcosmic features of EPS. This study suggests that vicK gene and EPS can be considered as promising targets to modulate dental caries.

Marine Bioactive Compounds as Nutraceutical and Functional Food Ingredients for Potential Oral Health

Oral diseases have received considerable attention worldwide as one of the major global public health problems. The development of oral diseases is influenced by socioeconomic, physiological, traumatic, biological, dietary and hygienic practices factors. Currently, the main prevention strategy for oral diseases is to inhibit the growth of biofilm-producing plaque bacteria. Tooth brushing is the most common method of cleaning plaque, aided by mouthwash and sugar-free chewing gum in the daily routine. As the global nutraceutical market grows, marine bioactive compounds are becoming increasingly popular among consumers for their antibacterial, anti-inflammatory and antitumor properties. However, to date, few systematic summaries and studies on the application of marine bioactive compounds in oral health exist. This review provides a comprehensive overview of different marine-sourced bioactive compounds and their health benefits in dental caries, gingivitis, periodontitis, halitosis, oral cancer, and their potential use as functional food ingredients for oral health. In addition, limitations and challenges of the application of these active ingredients are discussed and some observations on current work and future trends are presented in the conclusion section.

Utilizing heterologously overexpressed endo-1,3-fucanase to investigate the structure of sulfated fucan from sea cucumber (Holothuria hilla)

Sea cucumber sulfated fucan (SC-FUC) attracted increasing interests in the recent decades. Endo-1,3-fucanase has been employed in the structural clarification and structure-function relationship investigations of SC-FUC. Nevertheless, the preparation of wild-type endo-1,3-fucanase is costly and time-consuming, which hinders its further utilization. In this study, a heterologously overexpressed endo-1,3-fucanase (FunA) was introduced into structural identification of SC-FUC. FunA was efficiently prepared within one day and utilized in the investigation of sulfated fucan from sea cucumber Holothuria hilla (Hh-FUC). By using enzymatic degradation, glycomics and NMR analysis, the major structure of Hh-FUC was identified to be composed of a tetrasaccharide repeating unit →3-α-l-Fucp-1 → 3-α-l-Fucp2,4(OSO3-)-1 → 3-α-l-Fucp2(OSO3-)-1 → 3-α-l-Fucp2(OSO3-)-1→. Due to the efficient acquisition of enzyme and the superior oligosaccharide recovery, 0.6 mL of E. coli broth and 10 mg of Hh-FUC were sufficient for the structural identification. The results demonstrated the superiority of heterologously overexpressed fucanase over its wild-type enzyme in structural investigation of sulfated fucan.

Anti-hypertensive and cardioprotective activities of traditional Chinese medicine-derived polysaccharides: A review

Cardiovascular diseases (CVDs), a leading cause of death in modern society, have become a major public health issue globally. Although numerous approaches have been proposed to reduce morbidity and mortality, the pursuit of pharmaceuticals with more preventive and/or therapeutic value remains a focus of attention. Being a vast treasure trove of natural drug molecules, Traditional Chinese Medicine (TCM) has a long history of clinical use in the prophylaxis and remedy of CVDs. Increasing lines of preclinical evidence have demonstrated the effectiveness of TCM-derived polysaccharides on hindering the progression of CVDs, e.g. hypertension, myocardial infarction. However, to the best of our knowledge, there are few reviews on the application of TCM-derived polysaccharides in combating CVDs. Hence, we provide an overview of primary literature on the anti-hypertensive and cardioprotective activities of herbal polysaccharides. Additionally, we also discuss the current limitations and propose a new hypothesis about how polysaccharides exert cardiovascular effects based on the metabolism of polysaccharides.

Characterization of chondroitin sulfates isolated from large hybrid sturgeon cartilage and their gastroprotective activity against ethanol-induced gastric ulcers

Sturgeon cartilage, which is rich in chondroitin sulfate (CS), is usually discarded during sturgeon utilization. In this paper, CS was isolated from large hybrid sturgeon skull and backbone and named SCS and BCS, respectively. Their structures were investigated via Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and high performance liquid chromatography (HPLC). The average molecular weights of SCS and BCS were ~ 30-44 kDa. Disaccharide analysis indicated that SCS and BCS had similar chemical structures and were composed of ΔUA-[1 → 3]-GalNAc (ΔDi0S, 14.71%, 16.04%), ΔUA-[1 → 3]-GalNAc-4 s (ΔDi4S, 32.01%, 37.78%) and ΔUA-[1 → 3]-GalNAc-6 s (ΔDi6S, 53.27%, 46.18%). The gastroprotective effect of SCS and BCS were studied using a rat model of ethanol-induced gastric ulcers. Both SCS and BCS had apparent gastroprotective activity and their ulcer inhibition rate reached ~ 35%-45%, which was similar to that of omeprazole (~41%). These results provide useful strategies for the high-value utilization of sturgeon cartilage.

Structure-function relationship analysis of fucoidan from sea cucumber (Holothuria tubulosa) on ameliorating metabolic inflammation

The structure-function relationships of sea cucumber fucoidan has been seldom investigated. In this study, the effect of fucoidan which extracted from sea cucumber Holothuria tubulosa (Ht-FUC) with different molecular weight and chain conformation (Ht1/2/3/4) in metabolic inflammation was investigated. A co-cultured system comprising adipocytes and macrophages was used to explore the impact in vitro. The high-fat high-sucrose diet (HFD)-fed obese mice model was established to verified the effect of Ht-FUC in vivo. The results demonstrated that all examined Ht-FUC attenuated the productions of inflammatory cytokines, promoted the M2 phenotypic polarization of co-cultured macrophage by activating PPARγ. Furthermore Ht-FUC impressed lipolysis of the co-cultured adipocytes by inhibiting TLR4/NF-κB-dependent pathway. In vivo, Ht-FUC especially reduced serum inflammation level, attenuated M1/M2 polarization of liver Kupffer cells, and attenuated inflammatory infiltration of epididymal adipose tissue. Consistently, Ht3 played the best effect, and may be more beneficial for the intervention of metabolic disease. PRACTICAL APPLICATIONS: In this study, the structure-function relationships of fucoidan extracted from Holothuria tubulosa (Ht-FUC) on ameliorating metabolic inflammation was investigated for the first time. In this research, we reported that Ht-FUC ameliorating metabolic inflammation by improving FFA-induced macrophage polarization and lipolysis in both co-cultured system and obese mice. The study provides some theoretical basis for the high-value utilization of Ht-FUC with different molecular weight.

Investigation of structural proteins in sea cucumber (Apostichopus japonicus) body wall

Structural proteins play critical roles in the food quality, especially texture properties, of sea cucumbers and their products. Most of the previous studies on sea cucumbers focused on few individual proteins, which limited our understanding of how structural proteins influenced the quality of sea cucumbers. Inspired by the clarification of sea cucumber (Apostichopus japonicus) genome, we established an integrated data of structural proteins in the sea cucumber body wall. A portfolio of 2018 structural proteins was screened out from the sea cucumber annotated proteome by bioinformatics analysis. The portfolio was divided into three divisions, including extracellular matrix proteins, muscle proteins, and proteases, and further classified into 18 categories. The presence of 472 proteins in the sea cucumber body wall was confirmed by using a proteomics approach. Moreover, comparative proteomics analysis revealed the spatial distribution heterogeneity of structural proteins in the sea cucumber body wall at a molecular scale. This study suggested that future researches on sea cucumbers could be performed from an integrated perspective, which would reshape the component map of sea cucumber and provide novel insights into the understanding of how the food quality of sea cucumber was determined on a molecular level.

A Glycosaminoglycan-Rich Fraction from Sea Cucumber Isostichopus badionotus Has Potent Anti-Inflammatory Properties In Vitro and In Vivo

Sea cucumber body wall contains several naturally occurring bioactive components that possess health-promoting properties. Isostichopus badionotus from Yucatan, Mexico is heavily fished, but little is known about its bioactive constituents. We previously established that I. badionotus meal had potent anti-inflammatory properties in vivo. We have now screened some of its constituents for anti-inflammatory activity in vitro. Glycosaminoglycan and soluble protein preparations reduced 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammatory responses in HaCaT cells while an ethanol extract had a limited effect. The primary glycosaminoglycan (fucosylated chondroitin sulfate; FCS) was purified and tested for anti-inflammatory activity in vivo. FCS modulated the expression of critical genes, including NF-ĸB, TNFα, iNOS, and COX-2, and attenuated inflammation and tissue damage caused by TPA in a mouse ear inflammation model. It also mitigated colonic colitis caused in mice by dextran sodium sulfate. FCS from I. badionotus of the Yucatan Peninsula thus had strong anti-inflammatory properties in vivo.

Sulfated fucan/fucosylated chondroitin sulfate-dominated polysaccharide fraction from low-edible-value sea cucumber ameliorates type 2 diabetes in rats: New prospects for sea cucumber polysaccharide based-hypoglycemic functional food

Sulfated fucan chondroitin sulfate-dominated polysaccharide fraction from low-edible-value sea cucumber may be a good alternative to high-edible-value sea cucumber-derived polysaccharide for application in hypoglycemic functional foods. To evaluate the potential effect of low-edible-value sea cucumber-derived polysaccharide fraction on type 2 diabetes (T2DM), two sulfated fucan/fucosylated chondroitin sulfate-dominated polysaccharide fractions screening from 10 global commercial low-edible-value sea cucumber species were investigated to identify their anti-diabetics efficacies using a high-fat diet and streptozotocin-induced T2DM rat model. Sulfated fucan-dominated polysaccharide fraction from Thelenota ananas and fucosylated chondroitin sulfate-dominated polysaccharide fraction from Cucumaria frondosa ameliorated hyperglycemia, restored hypertriglyceridemia and hypercholesterolemia, decreased inflammatory status and oxidative stress, protected against liver injury, as well as improved insulin resistance and promoted accumulation of hepatic glycogen by activating IRS/PI3K/AKT signaling and regulating GSK-3β gene expression in T2DM rats. The current findings provide an available strategy for the commercialization of sea cucumber polysaccharide based-hypoglycemic functional food.

Gastric protective activities of fucoidan from brown alga Kjellmaniella crassifolia through the NF-κB signaling pathway

Fucoidan has been reported to have abundant biological activities. The objective of the present study was to detect the protective effects of fucoidan from Kjellmaniella crassifolia (KF) newly cultured in Dalian, North of China on aspirin-induced gastric ulcers of the Wistar rat model. The present study showed that inflammatory cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6 and IL-10 were effectively regulated in rats pretreated with KF. Superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities increased significantly in the KF pretreated groups, while the levels of maleic dialdehyde (MDA) decreased. The findings obtained by RT-PCR and western blotting indicated that KF could suppress aspirin-induced NF-κB activation via stabilization of IκB-α and thereby induced the downregulation of COX-2 and iNOS. It was demonstrated that KF exerted positive gastric protective effects via suppression of the inflammatory response and oxidative stress, and the mechanism of KF appeared to mediate the NF-κB signaling pathway.

Fucoidan A2 from the Brown Seaweed Ascophyllum nodosum Lowers Lipid by Improving Reverse Cholesterol Transport in C57BL/6J Mice Fed a High-Fat Diet

Reverse cholesterol transport (RCT) is a physiological process, in which excess peripheral cholesterol is transported to the liver and further excreted into the bile and then feces. Recently, fucoidans are reported to have a lipid-lowering effect. This study was designed to investigate whether fucoidan from the brown seaweed Ascophyllum nodosum lowers lipid by modulating RCT in C57BL/6J mice fed a high-fat diet. Our results indicated that fucoidan intervention significantly reduced plasma triglyceride, total cholesterol, and fat pad index and markedly increased high-density lipoprotein cholesterol in a dose-dependent manner. In the liver, fucoidan significantly increased the expression of peroxisome proliferator-activated receptor (PPAR)α, PPARγ, liver X receptor (LXR)β, adenosine triphosphate (ATP) binding cassette (ABC)A1, ABCG8, low-density lipoprotein receptor (LDLR), scavenger receptor B type 1 (SR-B1), and cholesterol 7-α-hydroxylase A1 (CYP7A1) and decreased the triglyceride level and expression of proprotein convertase subtilisin/kexin type 9 (PCSK9) and PPARβ but had no effect on LXRα, ABCG1, and ABCG5. In the small intestine, the fucoidan treatment significantly reduced the expression of Niemann-Pick C1-like 1 (NPC1L1) and improved ABCG5 and ABCG8. These results demonstrated that fucoidan can improve lipid transfer from plasma to the liver by activating SR-B1 and LDLR and inactivating PCSK9 and upregulate lipid metabolism by activating PPARα, LXRβ, ABC transporters, and CYP7A1. In the small intestine, this fucoidan can decrease cholesterol absorption and increase cholesterol excretion by activating NPC1L1 and ABCG5 and ABCG8, respectively. In conclusion, fucoidan from A. nodosum may lower lipids by modulating RCT-related protein expression and can be explored as a potential compound for prevention or treatment of hyperlipidemia-related diseases.

Biological Activities of Fucoidan and the Factors Mediating Its Therapeutic Effects: A Review of Recent Studies

The marine acid polysaccharide fucoidan has attracted attention from both the food and pharmaceutical industries due to its promising therapeutic effects. Fucoidan is a polysaccharide that mainly consists of L-fucose and sulphate groups. Its excellent biological function is attributed to its unique biological structure. Classical activities include antitumor, antioxidant, anticoagulant, antithrombotic, immunoregulatory, antiviral and anti-inflammatory effects. More recently, fucoidan has been shown to alleviate metabolic syndrome, protect the gastrointestinal tract, benefit angiogenesis and bone health. This review focuses on the progress in our understanding of the biological activities of fucoidan, highlighting its benefits for the treatment of human disease. We hope that this review can provide some theoretical basis and inspiration for the product development of fucoidan.