Structure and anticoagulant activity of a fucosylated chondroitin sulfate from echinoderm. Sulfated fucose branches on the polysaccharide account for its high anticoagulant action

Anti-respiratory syncytial virus and anti-herpes simplex virus activity of chemically engineered sulfated fucans from Cystoseira indica

Seaweed polysaccharides, particularly sulfated ones, exhibited potent antiviral activity against a wide variety of enveloped viruses, such as herpes simplex virus and respiratory viruses. Different mechanisms of action were suggested, which may range from preventing infection to intracellular antiviral activity, at different stages of the viral cycle. Herein, we generated two chemically engineered sulfated fucans (C303 and C304) from Cystoseira indica by an amalgamated extraction-sulfation procedure using chlorosulfonic acid-pyridine/N,N-dimethylformamide and sulfur trioxide-pyridine/N,N-dimethylformamide reagents, respectively. These compounds exhibited activity against HSV-1 and RSV with 50 % inhibitory concentration values in the range of 0.75-2.5 μg/mL and low cytotoxicity at concentrations up to 500 μg/mL. The antiviral activities of chemically sulfated fucans (C303 and C304) were higher than the water (C301) and CaCl2 extracted (C302) polysaccharides. Compound C303 had a (1,3)-linked fucan backbone and was branched. Sulfates were present at positions C-2, C-4, and C-2,4 of Fucp, and C-6 of Galp residues of this polymer. Compound C304 had a comparable structure but with more sulfates at C-4 of Fucp residue. Both C303 and C304 were potent antiviral candidates, acting in a dose-dependent manner on the adsorption and other intracellular stages of HSV-1 and RSV replication, in vitro.

Purification and Structural Analyses of Sulfated Polysaccharides from Low-Value Sea Cucumber Stichopus naso and Anticoagulant Activities of Its Oligosaccharides

Three polysaccharides (SnNG, SnFS and SnFG) were purified from the body wall of Stichopus naso. The physicochemical properties, including monosaccharide composition, molecular weight, sulfate content, and optical rotation, were analyzed, confirming that SnFS and SnFG are sulfated polysaccharides commonly found in sea cucumbers. The highly regular structure {3)-L-Fuc2S-(α1,}n of SnFS was determined via a detailed NMR analysis of its oxidative degradation product. By employing β-elimination depolymerization of SnFG, tri-, penta-, octa-, hendeca-, tetradeca-, and heptadeca-saccharides were obtained from the low-molecular-weight product. Their well-defined structures confirmed that SnFG possessed the backbone of {D-GalNAc4S6S-β(1,4)-D-GlcA}, and each GlcA residue was branched with Fuc2S4S. SnFS and SnFG are both structurally the simplest version of natural fucan sulfate and fucosylated glycosaminoglycan, facilitating the application of low-value sea cucumbers S. naso. Bioactivity assays showed that SnFG and its derived oligosaccharides exhibited potent anticoagulation and intrinsic factor Xase (iXase) inhibition. Moreover, a comparative analysis with the series of oligosaccharides solely branched with Fuc3S4S showed that in oligosaccharides with lower degrees of polymerization, such as octasaccharides, Fuc2S4S led to a greater increase in APTT prolongation and iXase inhibition. As the degree of polymerization increases, the influence from the sulfation pattern diminishes, until it is overshadowed by the effects of molecular weight.

A pyruvylated and sulfated galactan from the green alga Dictyosphaeria cavernosa: Structure, anticoagulant property and inhibitory effect on zebrafish thrombosis

A pyruvylated and sulfated galactan from the green alga Dictyosphaeria cavernosa, designated PSG, was obtained by dilute alkali extraction, ion-exchange and gel filtration chromatography. The backbone of PSG was composed of 3-linked β-d-Galp units with partial sulfation on C-4 and C-6. Pyruvate ketals were linked to O-3 and O-4 of nonreducing terminal β-d-Galp, as well as O-4 and O-6 of 3-linked β-d-Galp. The branches consisting of 6-linked β-d-Galp(4SO4) and β-d-Galp(3,4-Pyr)-(1→ units were located at C-6 of 3-linked β-d-Galp unit. PSG possessed obvious anticoagulant effect in vitro as assessed by the tests of activated partial thromboplastin time and thrombin time. The assay of anticoagulant mechanism showed that PSG promoted thrombin inactivation mediated by heparin cofactor-II and antithrombin-III (ATIII), and could effectively potentiate factor Xa inactivation by ATIII. The antithrombotic activity of PSG in vivo was assessed by phenylhydrazine (PHZ)-induced zebrafish thrombotic model. The results indicated that PSG obviously reduced peripheral erythrocytes aggregation, enhanced cardiac blood flow and improved peripheral platelet circulation, and PSG possessed a marked inhibitory effect on the PHZ-induced zebrafish thrombosis. Thus, PSG is a hopeful anticoagulant and antithrombotic polysaccharide.

Structural Characterization and Anticoagulant Activities of a Keratan Sulfate-like Polysaccharide from the Sea Cucumber Holothuria fuscopunctata

A sulfated polysaccharide (AG) was extracted and isolated from the sea cucumber H. fuscopunctata, consisting of GlcNAc, GalNAc, Gal, Fuc and lacking any uronic acid residues. Importantly, several chemical depolymerization methods were used to elucidate the structure of the AG through a bottom-up strategy. A highly sulfated galactose (oAG-1) and two disaccharides labeled with 2,5-anhydro-D-mannose (oAG-2, oAG-3) were obtained from the deaminative depolymerized product along with the structures of the disaccharide derivatives (oAG-4~oAG-6) identified from the free radical depolymerized product, suggesting that the repeating building blocks in a natural AG should comprise the disaccharide β-D-GalS-1,4-D-GlcNAc6S. The possible disaccharide side chains (bAG-1) were obtained with mild acid hydrolysis. Thus, a natural AG may consist of a keratan sulfate-like (KS-like) glycosaminoglycan with diverse modifications, including the sulfation types of the Gal residue and the possible disaccharide branches α-D-GalNAc4S6S-1,2-α/β-L-Fuc3S linked to the KS-like chain. Additionally, the anticoagulant activities of the AG and its depolymerized products (dAG1-9) were evaluated in vitro using normal human plasma. The AG could prolong activated partial thromboplastin time (APTT) in a dose-dependent manner, and the activity potency was positively related to the chain length. The AG and dAG1-dAG3 could prolong thrombin time (TT), while they had little effect on prothrombin time (PT). The results indicate that the AG could inhibit the intrinsic and common coagulation pathways.

Chondroitin Sulfate from Oreochromis niloticus Waste Reduces Leukocyte Influx in an Acute Peritonitis Model

Oreochromis niloticus (tilapia) is one of the most cultivated fish species worldwide. Tilapia farming generates organic waste from fish removal processes in nurseries. Visceral waste can damage natural ecosystems. Therefore, the use of this material as a source of biomolecules helps reduce environmental impacts and improve pharmacological studies. Tilapia viscera were subjected to proteolysis and complexation with an ion-exchange resin. The obtained glycosaminoglycans were purified using ion exchange chromatography (DEAE-Sephacel). The electrophoretic profile and analysis of 1H/13C nuclear magnetic resonance (NMR) spectra allowed for the characterization of the compound as chondroitin sulfate and its sulfation position. This chondroitin was named CST. We tested the ability of CST to reduce leukocyte influx in acute peritonitis models induced by sodium thioglycolate and found a significant reduction in leukocyte migration to the peritoneal cavity, similar to the polymorphonuclear population of the three tested doses of CST. This study shows, for the first time, the potential of CST obtained from O. niloticus waste as an anti-inflammatory drug, thereby contributing to the expansion of the study of molecules with pharmacological functions.

Fucosylated heparan sulfate from the midgut gland of Patinopecten yessoensis

The structural and functional relationships of glycosaminoglycans (GAGs) derived from marine organisms have been investigated, suggesting that marine invertebrates, particularly Bivalvia, are abundant sources of highly sulfated or branched GAGs. In this study, we identified a novel fucosylated heparan sulfate (Fuc-HS) from the midgut gland of the Japanese scallop, Patinopecten yessoensis. Scallop HS showed resistance to GAG-degrading enzymes, including chondroitinases and heparinases, and susceptibility to heparinases increased when scallop HS was treated with mild acid hydrolysis, which removes the fucosyl group. Moreover, ¹H NMR detected significant signals near 1.2-1.3 ppm corresponding to the H-6 methyl proton of fucose residues and small H-3 (3.59 ppm) or H-2 (3.39 ppm) signals of glucuronate (GlcA) were detected, suggesting that the fucose moiety is attached to the C-3 position of GlcA in scallop HS. GC-MS detected peaks corresponding to 1, 3, 5-tri-O-acetyl-2, 4-di-O-methyl-_L-fucitol and 1, 4, 5-tri-O-acetyl-2, 3-di-O-methyl-_L-fucitol, suggesting that the fucose moiety is 3-O- or 4-O-sulfated. Furthermore, scallop HS showed anti-coagulant and neurite outgrowth-promoting (NOP) activities. These results suggest that the midgut gland of scallops is a valuable source of Fuc-HS with biological activities.

Anticoagulant Property of a Sulfated Polysaccharide with Unique Structural Characteristics from the Green Alga Chaetomorpha aerea

Sulfated polysaccharides from marine algae have attracted a great amount of attentions for the development of marine drugs due to their unique structural features, and they are great potential sources of naturally occurring anticoagulant agents. The genus Chaetomorpha is one of the largest genera in green algae and has a worldwide distribution. In the present study, a homogeneous polysaccharide from Chaetomorpha aerea, designated as PCA, was obtained by alkali extraction, anion-exchange and size-exclusion chromatography. Based on the results of chemical and spectroscopic analyses, PCA was a sulfated galactoarabinan which was mainly constituted of a backbone of →4)-β-l-Arap-(1→ unit, partially sulfated at C-3 of →4)-β-l-Arap-(1→ and C-4 of →6)-α-d-Galp-(1→. The side chains consisting of →6)-α-d-Galp-(1→ and →5)-α-l-Araf-(1→ residues were in C-2 of →4)-β-l-Arap-(1→ unit. PCA had a strong anticoagulant activity in vitro as evaluated by the assays of activated partial thromboplastin time, thrombin time and fibrinogen level. The obvious anticoagulant activity in vivo of PCA was also found. PCA significantly inhibited the activities of the intrinsic coagulation factors XII, XI, IX and VIII, and exhibited weak inhibition effects on the common coagulation factors II and X. The anticoagulant mechanism of PCA was attributed to strong thrombin inhibition potentiated by heparin cofactor II or antithrombin III, and it also possessed an apparent inhibition effect on coagulation factor Xa mediated by antithrombin III. The investigation demonstrated that PCA could be a promising anticoagulant agent for health promotion and the treatment of thrombotic diseases.

Structural requirements of Holothuria floridana fucosylated chondroitin sulfate oligosaccharides in anti-SARS-CoV-2 and anticoagulant activities

Fucosylated chondroitin sulfate (FucCS) is a unique glycosaminoglycan found primarily in sea cucumbers. This marine sulfated glycan is composed of a chondroitin sulfate backbone decorated with fucosyl branches attached to the glucuronic acid. FucCS exhibits potential biological actions including inhibition of blood clotting and severe acute respiratory syndrome coronavirus (SARS-CoV-2) infection. These biological effects have been attributed to certain structural features, including molecular weight (MW), and/or those related to fucosylation, such as degrees of fucosyl branches, sulfation patterns and contents. In a previous work, we were able to generate oligosaccharides of the FucCS from Pentacta pygmaea (PpFucCS) with reduced anticoagulant effect but still retaining significant anti-SARS-CoV-2 activity against the delta strain. In this work, we extended our study to the FucCS extracted from the species Holothuria floridana (HfFucCS). The oligosaccharides were prepared by free-radical depolymerization of the HfFucCS via copper-based Fenton reaction. One-dimensional 1H nuclear magnetic resonance spectra were employed in structural analysis. Activated partial thromboplastin time and assays using protease (factors Xa and IIa) and serine protease inhibitors (antithrombin, and heparin cofactor II) in the presence of the sulfated carbohydrates were used to monitor anticoagulation. Anti-SARS-CoV-2 effects were measured using the concentration-response inhibitory curves of HEK-293T-human angiotensin-converting enzyme-2 cells infected with a baculovirus pseudotyped SARS-CoV-2 wild-type and delta variant spike (S)-proteins. Furthermore, the cytotoxicity of native HfFucCS and its oligosaccharides was also assessed. Like for PpFucCS, we were able to generate a HfFucCS oligosaccharide fraction devoid of high anticoagulant effect but still retaining considerable anti-SARS-CoV-2 actions against both variants. However, compared to the oligosaccharide fraction derived from PpFucCS, the average MW of the shortest active HfFucCS oligosaccharide fraction was significantly lower. This finding suggests that the specific structural feature in HfFucCS, the branching 3,4-di-sulfated fucoses together with the backbone 4,6-di-sulfated N-acetylgalactosamines, is relevant for the anti-SARS-CoV-2 activity of FucCS molecules.

Marine Biological Macromolecules and Chemically Modified Macromolecules; Potential Anticoagulants

Coagulation is a potential defense mechanism that involves activating a series of zymogens to convert soluble fibrinogen to insoluble fibrin clots to prevent bleeding and hemorrhagic complications. To prevent the extra formation and diffusion of clots, the counterbalance inhibitory mechanism is activated at levels of the coagulation pathway. Contrariwise, this system can evade normal control due to either inherited or acquired defects or aging which leads to unusual clots formation. The abnormal formations and deposition of excess fibrin trigger serious arterial and cardiovascular diseases. Although heparin and heparin-based anticoagulants are a widely prescribed class of anticoagulants, the clinical use of heparin has limitations due to the unpredictable anticoagulation, risk of bleeding, and other complications. Hence, significant interest has been established over the years to investigate alternative therapeutic anticoagulants from natural sources, especially from marine sources with good safety and potency due to their unique chemical structure and biological activity. This review summarizes the coagulation cascade and potential macromolecular anticoagulants derived from marine flora and fauna.

Re-understanding of structure and anticoagulation: Fucosylated chondroitin sulfate from sea cucumber Ludwigothurea grisea

Fucosylated chondroitin sulfate (FCS) from sea cucumber Ludwigothurea grisea (FCS_Lg) is the first one that reported to bear the di-fucosyl branches. Here we deciphered it by analyzing the physicochemical properties and its derivatives. Oligosaccharides prepared by selective cleavage of glycosidic linkages presented the mono-fucose and heterodisaccharide branches in FCS_Lg. The disaccharide branch was determined as d-GalNAc_R1-(α1,2)-l-Fuc_R2 rather than the di-fucosyl branch, where R1 was 4-mono-O- or 4,6-di-O-sulfation, and R2 was 3-mono-O- or 3,4-di-O-sulfation, respectively. The diversity of sulfation patterns in branches complicated the structure. These results give us a new understanding of FCS_Lg and provided a reliable method to decipher the FCS with complex branches. Bioanalysis of chemically modified derivatives showed that modulating the molecular mass could enhance the Xase target selectivity. Side chains conferred the Xase complex inhibition by binding to FIXa with a high affinity. Whether monosaccharide and disaccharide branches have differential effects needs to be further explored.

Sulfated Polysaccharide Extracted from the Green Algae Codium bernabei: Physicochemical Characterization and Antioxidant, Anticoagulant and Antitumor Activity

Codium bernabei is a green alga that grows on Chilean coasts. The composition of its structural polysaccharides is still unknown. Hence, the aim of this work is to isolate and characterize the hot water extracted polysaccharide fractions. For this purpose, the water extracts were further precipitated in alcohol (TPs) and acid media (APs), respectively. Both fractions were characterized using different physicochemical techniques such as GC-MS, GPC, FTIR, TGA, and SEM. It is confirmed that the extracted fractions are mainly made of sulfated galactan unit, with a degree of sulfation of 19.3% (TPs) and 17.4% (ATs) and a protein content of 3.5% in APs and 15.6% in TPs. Other neutral sugars such as xylose, glucose, galactose, fucose, mannose, and arabinose were found in a molar ratio (0.05:0.6:1.0:0.02:0.14:0.11) for TPs and (0.05:0.31:1.0:0.03:0.1:0.13) for ATs. The molecular weight of the polysaccharide samples was lower than 20 kDa. Both polysaccharides were thermally stable (Tonset > 190 °C) and showed antioxidant activity according to the ABTS•+ and DPPH tests, where TPs fractions had higher scavenging activity (35%) compared to the APs fractions. The PT and APTTS assays were used to measure the anticoagulant activity of the polysaccharide fractions. In general, the PT activity of the TPs and APs was not different from normal plasma values. The exception was the TPs treatment at 1000 µg mL−1 concentration. The APTTS test revealed that clotting time for both polysaccharides was prolonged regarding normal values at 1000 µg mL−1. Finally, the antitumor test in colorectal carcinoma (HTC-116) cell line, breast cancer (MCF-7) and human leukemia (HL-60) cell lines showed the cytotoxic effect of TPs and APs. Those results suggest the potential biotechnological application of sulfate galactan polysaccharides isolated from a Chilean marine resource.

Preparation of Low-Molecular-Weight Fucoidan with Anticoagulant Activity by Photocatalytic Degradation Method

It is a challenge to degrade sulfated polysaccharides without stripping sulfate groups. In the present study, a photocatalytic method was applied to degrade fucoidan, a sulfated polysaccharide from brown algae. The degradation with varying addition amounts of H₂O₂ and TiO₂ were monitored by high performance gel permeation chromatography (HPGPC) and thin layer chromatography (TLC), and fucoidan was efficiently degraded with 5% TiO₂ and 0.95% H₂O₂. A comparison of the chemical compositions of 2 products obtained after 0.5 h and 3 h illumination, DF-0.5 (average Mw 90 kDa) and DF-3 (average Mw 3 kDa), respectively, with those of fucoidan indicates the photocatalytic degradation did not strip the sulfate groups, but reduced the galactose/fucose ratio. Moreover, 12 oligosaccharides in DF-3 were identified by HPLC-ESI-MSⁿ and 10 of them were sulfated. In addition, DF-0.5 showed anticoagulant activity as strong as fucoidan while DF-3 could specifically prolong the activated partial thromboplastin time. All samples exerted inhibition effects on the intrinsic pathway FXII in a dose-dependent manner. Thus, photocatalytic degradation demonstrated the potential to prepare sulfated low-molecular-weight fucoidan with anticoagulant activity.

The glycosidic bond cleavage and desulfation investigation of fucosylated glycosaminoglycan during mild acid hydrolysis through structural analysis of the resulting oligosaccharides

Mild acid hydrolysis is a common method to study the chemical structure of fucosylated glycosaminoglycan (FG). It was generally considered that the fucose branches α-L-FucS-(1, of FG could be hydrolyzed selectively in mild acid. This report focused on the selectivity of glycosidic bond cleavage and extensive desulfation characteristics of the backbone during mild acid hydrolysis. The hydrolyzed product of native SvFG (dfSvFG) was prepared by mild acid hydrolysis in 0.1 M H₂SO₄ at 100 °C for 2 h. A series of oligosaccharides were purified by GPC and SAX-HPLC from dfSvFG, then they were analyzed by HPGPC, 1D/2D NMR and ESI-Q-TOF-MS. The precise structure of these oligosaccharides was elucidated to be trisaccharides, tetrasaccharides and pentasaccharides, indicating SvFG branches hydrolyzed basically and its' backbone composed of repeating β-D-GlcA-(1,3)-D-GalNAc and β-D-GalNAc-(1,4)-D-GlcA unit. The prevalent presence of the GlcA residues at the non-reducing terminal of these oligosaccharides, suggesting the glycosidic bond of β-D-GalNAc-(1,4)-D-GlcA was more susceptible to acid than that of β-D-GlcA-(1,3)-D-GalNAc during mild acid hydrolysis. Moreover, the sulfate ester groups in GalNAc_4S6S unit could also be hydrolyzed by acid, and it at position C-4 was more susceptible to hydrolysis than that at C-6. This extensive degradation and desulfation of the backbone should be taken into consideration when mild acid hydrolysis was used in elucidating the exact structure or structure-activity relationship of native FG.

Recent Advancements and Future Perspectives of Microalgae-Derived Pharmaceuticals

Microalgal cells serve as solar-powered factories that produce pharmaceuticals, recombinant proteins (vaccines and drugs), and valuable natural byproducts that possess medicinal properties. The main advantages of microalgae as cell factories can be summarized as follows: they are fueled by photosynthesis, are carbon dioxide-neutral, have rapid growth rates, are robust, have low-cost cultivation, are easily scalable, pose no risk of human pathogenic contamination, and their valuable natural byproducts can be further processed. Despite their potential, there are many technical hurdles that need to be overcome before the commercial production of microalgal pharmaceuticals, and extensive studies regarding their impact on human health must still be conducted and the results evaluated. Clearly, much work remains to be done before microalgae can be used in the large-scale commercial production of pharmaceuticals. This review focuses on recent advancements in microalgal biotechnology and its future perspectives.

Antiparasitic Effects of Sulfated Polysaccharides from Marine Hydrobionts

This review presents materials characterizing sulfated polysaccharides (SPS) of marine hydrobionts (algae and invertebrates) as potential means for the prevention and treatment of protozoa and helminthiasis. The authors have summarized the literature on the pathogenetic targets of protozoa on the host cells and on the antiparasitic potential of polysaccharides from red, brown and green algae as well as certain marine invertebrates. Information about the mechanisms of action of these unique compounds in diseases caused by protozoa has also been summarized. SPS is distinguished by high antiparasitic activity, good solubility and an almost complete absence of toxicity. In the long term, this allows for the consideration of these compounds as effective and attractive candidates on which to base drugs, biologically active food additives and functional food products with antiparasitic activity.

Structural characterization and anticoagulant analysis of the novel branched fucosylated glycosaminoglycan from sea cucumber Holothuria nobilis

Glycosaminoglycan HnFG was extracted from sea cucumber Holothuria nobilis. Its chemical structure was characterized by analyzing the physicochemical properties, oligosaccharides from its mild acid hydrolysates and depolymerized products. The disaccharide d-GalNAc_4S6S-α1,2-l-Fuc_3S-ol found in its mild acid hydrolysates provided a clue for the presence of a unique disaccharide-branch in HnFG. Furthermore, it was confirmed by a series of oligosaccharides from the low-molecular weight HnFG prepared by β-eliminative depolymerization. Combining with the analysis of its peroxide depolymerized products, the precise structure of HnFG was determined: A chondroitin sulfate E (CS-E)-like backbone branched with sulfated monofucoses (~67%) and disaccharides d-GalNAc_S-α1,2-l-Fuc_3S (~33%) at O-3 position of each GlcUA. This is the first report on the novel branches in glycosaminoglycan. Biologically, the native and depolymerized HnFG showed potent activities in prolonging the activated partial thrombin time (APTT) and inhibiting intrinsic coagulation Xase (iXase), whereas the oligosaccharides (degree of polymerization ≤6) had no obvious effects.

Structural and kinetic analyses of holothurian sulfated glycans suggest potential treatment for SARS-CoV-2 infection

Certain sulfated glycans, including those from marine sources, can show potential effects against SARS-CoV-2. Here, a new fucosylated chondroitin sulfate (FucCS) from the sea cucumber Pentacta pygmaea (PpFucCS) (MW ∼10-60 kDa) was isolated and structurally characterized by NMR. PpFucCS is composed of {→3)-β-GalNAcX-(1→4)-β-GlcA-[(3→1)Y]-(1→}, where X = 4S (80%), 6S (10%) or nonsulfated (10%), Y = α-Fuc2,4S (40%), α-Fuc2,4S-(1→4)-α-Fuc (30%), or α-Fuc4S (30%), and S = SO3-. The anti-SARS-CoV-2 activity of PpFucCS and those of the FucCS and sulfated fucan isolated from Isostichopus badionotus (IbFucCS and IbSF) were compared with that of heparin. IC50 values demonstrated the activity of the three holothurian sulfated glycans to be ∼12 times more efficient than heparin, with no cytotoxic effects. The dissociation constant (KD) values obtained by surface plasmon resonance of the wildtype SARS-CoV-2 spike (S)-protein receptor-binding domain (RBD) and N501Y mutant RBD in interactions with the heparin-immobilized sensor chip were 94 and 1.8 × 103 nM, respectively. Competitive surface plasmon resonance inhibition analysis of PpFucCS, IbFucCS, and IbSF against heparin binding to wildtype S-protein showed IC50 values (in the nanomolar range) 6, 25, and 6 times more efficient than heparin, respectively. Data from computational simulations suggest an influence of the sulfation patterns of the Fuc units on hydrogen bonding with GlcA and that conformational change of some of the oligosaccharide structures occurs upon S-protein RBD binding. Compared with heparin, negligible anticoagulant action was observed for IbSF. Our results suggest that IbSF may represent a promising molecule for future investigations against SARS-CoV-2.

Chemical Structure and Anticoagulant Property of a Novel Sulfated Polysaccharide from the Green Alga Cladophora oligoclada

Marine macroalgae are efficient producers of sulfated polysaccharides. The algal sulfated polysaccharides possess diverse bioactivities and peculiar chemical structures, and represent a great potential source to be explored. In the present study, a heparinoid-active sulfated polysaccharide was isolated from the green alga Cladophora oligoclada. Results of chemical and spectroscopic analyses indicated that the sulfated polysaccharide was composed of →6)-β-d-Galp-(1→, β-d-Galp-(1→, →6)-α-d-Glcp-(1→ and →3)-β-d-Galp-(1→ units with sulfate esters at C-2/C-4 of →6)-β-d-Galp-(1→, C-6 of →3)-β-d-Galp-(1→ and C-3 of →6)-α-d-Glcp-(1→ units. The branches consisting of β-d-Galp-(1→ and →6)-β-d-Galp-(1→ units were located in C-3 of →6)-β-d-Galp-(1→ units. The sulfated polysaccharide exhibited potent anticoagulant activity in vitro and in vivo as evaluated by activated partial thromboplastin time (APTT), thrombin time, and the fibrinogen level. For the APTT, the signal for clotting time was more than 200 s at 100 μg/mL in vitro and at 15 mg/kg in vivo. The obvious thrombolytic activity of the sulfated polysaccharide in vitro was also found. The mechanism analysis of anticoagulant action demonstrated that the sulfated polysaccharide significantly inhibited the activities of all intrinsic coagulation factors, which were less than 1.0% at 50 μg/mL, but selectively inhibited common coagulation factors. Furthermore, the sulfated polysaccharide strongly stimulated the inhibition of thrombin by potentiating antithrombin-III (AT-III) or heparin cofactor-II, and it also largely promoted the inhibition of factor Xa mediated by AT-III. These results revealed that the sulfated polysaccharide from C. oligoclada had potential to become an anticoagulant agent for prevention and therapy of thrombotic diseases.

Pharmacological Activities of Sulfated Fucose-Rich Polysaccharides after Oral Administration: Perspectives for the Development of New Carbohydrate-Based Drugs

Marine organisms are a source of active biomolecules with immense therapeutic and nutraceutical potential. Sulfated fucose-rich polysaccharides are present in large quantities in these organisms with important pharmacological effects in several biological systems. These polysaccharides include sulfated fucan (as fucoidan) and fucosylated chondroitin sulfate. The development of these polysaccharides as new drugs involves several important steps, among them, demonstration of the effectiveness of these compounds after oral administration. The oral route is the more practical, comfortable and preferred by patients for long-term treatments. In the past 20 years, reports of various pharmacological effects of these polysaccharides orally administered in several animal experimental models and some trials in humans have sparked the possibility for the development of drugs based on sulfated polysaccharides and/or the use of these marine organisms as functional food. This review focuses on the main pharmacological effects of sulfated fucose-rich polysaccharides, with an emphasis on the antidislipidemic, immunomodulatory, antitumor, hypoglycemic and hemostatic effects.

Inhibition of mild steel corrosion in 1 M HCl by chondroitin sulfate and its synergistic effect with sodium alginate

The development of effective and environment-friendly corrosion inhibitors is of great significance for the protection of mild steel in hydrochloric acid media. Accordingly, a natural polysaccharide mixture inhibitor composed of chondroitin sulfate derived from pig cartilage (CS-PC) and sodium alginate (SA) is developed here, and the synergistic effect of the two polysaccharides towards adsorption on mild steel in 1 M HCl is studied. The inhibition performance has been studied using weight loss test, electrochemical investigations, SEM, SECM and UV methods. The results indicate that the mixtures of CS-PC and SA strongly inhibit the corrosion of mild steel compared to individual inhibitors (i.e., 95.18 % versus 72.78 %), and show a synergistic inhibition effect. The structure-activity relationship between the molecular structure of the CS-PC + SA mixture and its corrosion inhibition performance has been discussed by using the quantum chemistry calculation and molecular dynamics simulations. It is believed that these results have certain guiding significance for the rational design of efficient corrosion inhibitor.

Structural elucidation and antidiabetic activity of fucosylated chondroitin sulfate from sea cucumber Stichopus japonicas

A fucosylated chondroitin sulfate was isolated from the body wall of sea cucumber Stichopus japonicus (FCSsj), whose structure was characterized by NMR spectroscopy and HILIC-FTMS. At the ratio of 1.00:0.26:0.65, three fucosyl residues were found: 2,4-disulfated-fucose (Fuc2,4S), 4-sulfated-fucose (Fuc4S) and 3,4-disulfated-fucose (Fuc3,4S), which were only linked to the O-3 of glucuronic acid residues (GlcA). Besides mono-fucosyl moieties, di-fucosyl branches, namely Fuc2,4Sα(1→3)Fuc4S, were also found to be attached to the O-3 of GlcA. The antidiabetic activity of FCSsj was evaluated using glucosamine induced insulin resistant (IR) Hep G2 cells in vitro. It was found that FCSsj significantly promoted the glucose uptake and glucose consumption of IR-Hep G2 cells in a dose-dependent manner, and could alleviate the cell damage. Furthermore, FCSsj could promote the glycogen synthesis in the glucosamine-induced IR-Hep G2 cells. These results provided a supplement for studying the antidiabetic activity of FCSsj.

Structural Characterization and Heparanase Inhibitory Activity of Fucosylated Glycosaminoglycan from Holothuria floridana

Unique fucosylated glycosaminoglycans (FG) have attracted increasing attention for various bioactivities. However, the precise structures of FGs usually vary in a species-specific manner. In this study, HfFG was isolated from Holothuria floridana and purified by anion exchange chromatography with the yield of ~0.9%. HfFG was composed of GlcA, GalNAc and Fuc, its molecular weight was 47.3 kDa, and the -OSO3-/-COO- molar ratio was 3.756. HfFG was depolymerized by a partial deacetylation-deaminative cleavage method to obtain the low-molecular-weight HfFG (dHfFG). Three oligosaccharide fragments (Fr-1, Fr-2, Fr-3) with different molecular weights were isolated from the dHfFG, and their structures were revealed by 1D and 2D NMR spectroscopy. HfFG should be composed of repeating trisaccharide units -{(L-FucS-α1,3-)d-GlcA-β1,3-d-GalNAc4S6S-β1,4-}-, in which sulfated fucose (FucS) includes Fuc2S4S, Fuc3S4S and Fuc4S residues linked to O-3 of GlcA in a ratio of 45:35:20. Furthermore, the heparanase inhibitory activities of native HfFG and oligosaccharide fragments (Fr-1, Fr-2, Fr-3) were evaluated. The native HfFG and its oligosaccharides exhibited heparanase inhibitory activities, and the activities increased with the increase of molecular weight. Additionally, structural characteristics such as sulfation patterns, the terminal structure of oligosaccharides and the presence of fucosyl branches may be important factors affecting heparanase inhibiting activity.

Unveiling the Disaccharide-Branched Glycosaminoglycan and Anticoagulant Potential of Its Derivatives

Glycosaminoglycans (GAGs) are conserved polysaccharides composed of linear repeating disaccharides and play crucial roles in multiple biological processes in animal kingdom. However, saccharide-branched GAGs are rarely found, except the fucose-branched one from sea cucumbers. There was conjecture about the presence of disaccharide-branched GAG since 30 years ago, though not yet confirmed. Here, we report a GAG containing galactose-fucose branches from Thelenota ananas. This unique branch was confirmed as d-Gal_4S(6S)-α1,2-l-Fuc_3S by structural elucidation of oligosaccharides prepared from T. ananas GAG. Bioassays indicated that oligomers with a larger degree of polymerization exhibited a potent anticoagulation by targeting the intrinsic tenase. Heptasaccharide was proven as the minimum fragment retaining the anticoagulant potential and showed 92.6% inhibition of venous thrombosis in vivo at sc. of 8 mg/kg with no obvious bleeding risks. These results not only solve a long-standing question about the presence of disaccharide-branched GAG in Holothuroidea, but open up new opportunities to develop safer anticoagulants.

Characterization and Evaluation of the Pro-Coagulant and Immunomodulatory Activities of Polysaccharides from Bletilla striata

Bletilla striata is widely used for stanching bleeding. In this study, polysaccharides from B. striata (BSP) were extracted by hot water. Four polysaccharides named BSP-1-BSP-4 were fractionated using DEAE-52 cellulose. BSP fractions contained sulfate, and the degrees of substitution of BSP-3 and BSP-4 were 1.59 and 1.70, respectively. Analysis of monosaccharide composition showed that four polysaccharides were mainly composed of mannan and glucose. The in vitro results showed that BSP-1-BSP-4 elicited pro-coagulant capacities by shortening the activating partial thromboplastin time, prothrombin time, and thrombin time and elevating the fibrinogen content. Immunomodulatory activity was evaluated by MTT assay, the pinocytic capacity and NO production. Although BSP fractions did not affect RAW 264.7 cell viability, they, especially BSP-2, enhanced the immunomodulatory activity by increasing the pinocytic capacity and NO production. Overall, BSP may be developed as a potential coagulant with immunomodulatory effects.

Oral Administration of Fucosylated Chondroitin Sulfate Oligomers in Gastro-Resistant Microcapsules Exhibits a Safe Antithrombotic Activity

Fucosylated chondroitin sulfate (FCS) polysaccharide isolated from sea cucumber has potent anticoagulant activity. Based on its resistance to the enzymes present in vertebrates, it may serve as an anticoagulant and shows antithrombotic effects when delivered through gastro-resistant (GR) tablets. However, due to the multiple plasma targets of FCS polysaccharide in the coagulation pathway, bleeding can occur after its oral administration. In the current study, we used FCS oligomers, in particular a mixture of oligosaccharides having 6 to 18 saccharide units, as the active ingredient in GR microcapsules for oral anticoagulation. In a Caco-2 model, the FCS oligomers showed higher absorption than native FCS polysaccharides. Oral administration of FCS oligomer-GR microcapsules provided a dose-dependent, prolonged anticoagulant effect with a selective inhibition of the intrinsic coagulation pathway when compared with subcutaneous administration of FCS oligomers or oral administration of unformulated FCS oligomers or native FCS-GR microspheres. Continued oral administration of FCS oligomer-GR microcapsules did not result in the accumulation of oligosaccharides in the plasma. Venous thrombosis animal models demonstrated that FCS oligomers delivered via GR microcapsules produced a potent antithrombotic effect dependent on their anticoagulant properties in the plasma, while oral administration of unformulated FCS oligomers at the same dose exhibited a weaker antithrombotic effect than the formulated version. Oral administration of FCS oligomer-GR microcapsules resulted in no bleeding, while oral administration of native FCS-GR microcapsules resulted in bleeding (p < 0.05). Our present results suggest that a FCS oligomer-GR microcapsule formulation represents an effective and safe oral anticoagulant for potential clinical applications.

Structural sequencing and anti-inflammatory, anti-lung cancer activities of 1,4-α/β-sulfomalonoglucan in Antrodia cinnamomea

Antrodia cinnamomea is a precious Polyporaceous fungus with various bioactivities. This study reports the chemical identification and biological activities of sulfomalonoglucan, a sulfated polysaccharide (SPS), from the sodium sulfate enriched medium of the title fungus. The SPS-containing fraction was separated by gel filtration chromatography (GFC) to give the title SPS (denoted as Na10_SPS-F3). By analyzing the evidence for key inter-glycosidic linkages in the 1D and 2D NMR spectroscopic data, one possible repeat unit was proposed as: Na10_SPS-F3 inhibited the secretion of tumor necrosis factor (TNF-α) and interleukin (IL)-6 after lipopolysaccharide (LPS) stimulation in RAW264.7 macrophages. Mechanistically, Na10_SPS-F3 downregulated TGFRII also attenuated the LPS-induced IκB-α degradation. Moreover, Na10_SPS-F3 inhibited lung cancer cell H1975 EGFR/ERK signaling. This is the first paper reporting a 3-O-sulfomalonyl glucan (Na10_SPS-F3) with eight 1,4-β-Glc moieties connected with ten 1,4-α-Glc moieties from Antrodia cinnamomea and its anti-inflammatory and anti-cancer activities.

Chemical Synthesis of Fucosylated Chondroitin Sulfate Oligosaccharides

Fucosylated chondroitin sulfates (FuCSs) are a unique type of polysaccharides occurring in sea cucumber that show a variety of biological activities. In particular, well-defined FuCS oligosaccharides, consisting of a trisaccharide repeating unit of β-d-GalNAc(4,6-diS)-(1→4)-[α-l-Fuc(2,4-diS)-(1→3)]-β-d-GlcUA, display potent anticoagulant activity via selective inhibition of the intrinsic tenase, which could be developed into anticoagulant drugs without bleeding risk. Herein, we report an effective approach to the synthesis of FuCS oligosaccharides, as demonstrated by the successful elaboration of FuCS tri-, hexa-, and nonasaccharides. The syntheses employ an orthogonally protected trisaccharide as a pivotal building block that can be readily converted into the donor and acceptor for glycosidic coupling. In addition, the internal patterns of protecting groups, involving N-trichloroacetyl for N-acetyl group, benzylidene and benzyl groups for sulfonated hydroxyl groups, and benzoyl and methyl esters for free hydroxyl and carboxylic acid, respectively, ensure stereoselective formation of the glycosidic linkages and sequential transformation into the desired FuCS oligosaccharides.

Fabrication of chondroitin sulfate calcium complex and its chondrocyte proliferation in vitro

Chondroitin sulfate (CS)-calcium complex (CSCa) was fabricated, and the structural characteristics of CSCa and its proliferative bioactivity to the chondrocyte were investigated in vitro. Results suggested calcium ions could bind CS chains forming polysaccharide-metal complex, and the maximum calcium holding capacity of CSCa reached 4.23 %. Characterization of CSCa was performed by EDS, AFM, FTIR, UV, XRD and 1H-NMR. It was found that calcium ions were integrated with CS by binding the sulfate or carboxyl groups. The thermal properties analysis indicated CSCa had a good thermal stability by TGA and DSC. CSCa could interact the calcium-sensing receptor increasing the intracellular calcium ions and influence the cell cycle. The TGF-β1 secretion induced by CSCa could activate the TGF-β/Smads pathway and change the genes associated proliferation expression ultimately leading to the chondrocyte proliferation. This research probably has an important implication for understanding the effect of CSCa on bone care as food supplements.

Fucosylated Chondroitin Sulfate 9-18 Oligomers Exhibit Molecular Size-Independent Antithrombotic Activity while Circulating in the Blood

Fucosylated chondroitin sulfate (FCS) oligosaccharides extracted from sea cucumber and depolymerized exhibit potent anticoagulant activity. Knowledge of the antithrombotic activity of different size oligosaccharides and their fucose (Fuc) branch sulfation pattern should promote their development for clinical applications. We prepared highly purified FCS trisaccharide repeating units from hexasaccharide (6-mer) to octadecasaccharide (18-mer), including those with 2,4-disulfated and 3,4-disulfated Fuc branches. All 10 oligosaccharides were identified by their nuclear magnetic resonance structures and ESI-FTMS spectroscopy. In vitro anticoagulant activities and surface plasmon resonance binding tests indicated those of larger molecular sizes and 2,4-disulfated Fuc branches showed stronger anticoagulant effects with respect to anti-FXase activity, as well as stronger binding to FIXa among various clotting proteins. However, both types of FCS 9-mer to 18-mer exhibited molecular size-independent potent antithrombotic activity in vivo at the same dose. In addition, both types of the FCS 6-mer exhibited favorable antithrombotic activity in vivo, although they showed weak anticoagulant activity in vitro. Combining absorption and metabolism studies, we conclude that FCS 9-18 oligomers could remain in the circulation to interact with various clotting proteins to prevent thrombus formation, and appreciable quantities of these oligomers could be excreted through the kidneys. All FCS 9-18 oligomers also resulted in no bleeding, hypotension, or platelet aggregation risk during blood circulation. Thus, FCS 9-18 oligomers with 2,4-disulfated or 3,4-disulfated Fuc branches exhibit potent and safe antithrombotic activity needed for clinical applications.

(Semi)-Synthetic Fucosylated Chondroitin Sulfate Oligo- and Polysaccharides

Fucosylated chondroitin sulfate (fCS) is a glycosaminoglycan (GAG) polysaccharide with a unique structure, displaying a backbone composed of alternating N-acetyl-d-galactosamine (GalNAc) and d-glucuronic acid (GlcA) units on which l-fucose (Fuc) branches are installed. fCS shows several potential biomedical applications, with the anticoagulant activity standing as the most promising and widely investigated one. Natural fCS polysaccharides extracted from marine organisms (Echinoidea, Holothuroidea) present some advantages over a largely employed antithrombotic drug such as heparin, but some adverse effects as well as a frequently found structural heterogeneity hamper its development as a new drug. To circumvent these drawbacks, several efforts have been made in the last decade to obtain synthetic and semi-synthetic fCS oligosaccharides and low molecular weight polysaccharides. In this Review we have for the first time collected these reports together, dividing them in two topics: (i) total syntheses of fCS oligosaccharides and (ii) semi-synthetic approaches to fCS oligosaccharides and low molecular weight polysaccharides as well as glycoclusters displaying multiple copies of fCS species.

Characterization of the Hydrolysis Kinetics of Fucosylated Glycosaminoglycan in Mild Acid and Structures of the Resulting Oligosaccharides

: Mild acid hydrolysis is a common method for the structure analysis of fucosylated glycosaminoglycan (FG). In this work, the effects of acid hydrolysis on the structure of FG from S. variegatus (SvFG) and the reaction characteristic were systemically studied. The degree of defucosylation (DF) and molecular weights (Mw) of partial fucosylated glycosaminoglycans (pFs) were monitored by 1H NMR and size-exclusion chromatography, respectively. The kinetic plots of DF, degree of desulfation (DS) from fucose branches, and degree of hydrolysis (DH) of the backbone are exponentially increased with time, indicating that acid hydrolysis of SvFG followed a first-order kinetics. The kinetic rate constants kDF, kDS, and kDH were determined to be 0.0223 h-1, 0.0041 h-1, and 0.0005 h-1, respectively. The structure of the released sulfated fucose branches (FucS) from SvFG and HfFG (FG from H. fuscopunctata) was characterized by 1D/2D NMR spectroscopy, suggesting the presence of six types of fucose: α/β Fuc2S4S, Fuc3S4S, Fuc3S, Fuc4S, Fuc2S, and Fuc. The Fuc3S4S was more susceptible to acid than Fuc2S4S, and that the sulfate ester in position of O-2 and O-3 than in O-4 of fucose. The structure characteristic of pF18 indicated the cleavage of backbone glycosidic bonds. The APTT prolonged activity reduced with the decrease of the DF and Mw of the pFs, and became insignificant when its DF was 87% with Mw of 3.5 kDa.

Anticoagulant-active sulfated arabinogalactan from Chaetomorpha linum: Structural characterization and action on coagulation factors

A sulfated polysaccharide from the green alga Chaetomorpha linum, designated CLS4, was isolated by water extraction, anion-exchange and size-exclusion chromatography. Chemical and spectroscopic analyses demonstrated that CLS4 was a sulfated arabinogalactan, which was constituted by (1→6)-β-d-galactopyranose and (1→5)-α-l-arabinofuranose residues with sulfate groups at C-2/ C-3 of (1→5)-α-l-arabinofuranose and C-2/C-4 of (1→6)-β-d-galactopyranose. CLS4 possessed strong anticoagulant activity in vitro or in vivo as evaluated by activated partial thromboplastin time and thrombin time assays. CLS4 largely inhibited the activities of the coagulation factors XII, XI, IX and VIII. CLS4 was a potent thrombin inhibitor mediated by antithrombin III (ATIII) or heparin cofactor II, and it also effectively stimulated the factor Xa inhibition by potentiating ATIII. Moreover, CLS4 had a high thrombolytic activity in vitro as assessed by clot lytic rate assay. The results suggested that CLS4 could be a promising source of anticoagulant agent.

Northern Sea Cucumber (Cucumaria frondosa): A Potential Candidate for Functional Food, Nutraceutical, and Pharmaceutical Sector

Sea cucumber (Cucumaria frondosa) is the most abundant and widely distributed species in the cold waters of North Atlantic Ocean. C. frondosa contains a wide range of bioactive compounds, mainly collagen, cerebrosides, glycosaminoglycan, chondroitin sulfate, saponins, phenols, and mucopolysaccharides, which demonstrate unique biological and pharmacological properties. In particular, the body wall of this marine invertebrate is the major edible part and contains most of the active constituents, mainly polysaccharides and collagen, which exhibit numerous biological activities, including anticancer, anti-hypertensive, anti-angiogenic, anti-inflammatory, antidiabetic, anti-coagulation, antimicrobial, antioxidation, and anti- osteoclastogenic properties. In particular, triterpene glycosides (frondoside A and other) are the most researched group of compounds due to their potential anticancer activity. This review summarizes the latest information on C. frondosa, mainly geographical distribution, landings specific to Canadian coastlines, processing, commercial products, trade market, bioactive compounds, and potential health benefits in the context of functional foods and nutraceuticals.

Glycosaminoglycan from Apostichopus japonicus Improves Glucose Metabolism in the Liver of Insulin Resistant Mice

Holothurian glycosaminoglycan isolated from Apostichopus japonicus (named AHG) can suppress hepatic glucose production in insulin resistant hepatocytes, but its effects on glucose metabolism in vivo are unknown. The present study was conducted to investigate the effects of AHG on hyperglycemia in the liver of insulin resistant mice induced by a high-fat diet (HFD) for 12 weeks. The results demonstrated that AHG supplementation apparently reduced body weight, blood glucose level, and serum insulin content in a dose-dependent manner in HFD-fed mice. The protein levels and gene expression of gluconeogenesis rate-limiting enzymes G6Pase and PEPCK were remarkedly suppressed in the insulin resistant liver. In addition, although the total expression of IRS1, Akt, and AMPK in the insulin resistant liver was not affected by AHG supplementation, the phosphorylation of IRS1, Akt, and AMPK were clearly elevated by AHG treatment. These results suggest that AHG could be a promising natural marine product for the development of an antihyperglycemic agent.

Two different fucosylated chondroitin sulfates: Structural elucidation, stimulating hematopoiesis and immune-enhancing effects

Two fucosylated chondroitin sulfates FCS_hp and FCS_ht were isolated from the sea cucumber Holothuria polii and Holothuria tubulosa, respectively. The NMR spectroscopy and HILIC-FTMS methods were applied for their detailed structural characterization. Chemical analysis indicated that the two FCSs all contained a chondroitin sulfate backbone chondroitin sulfate-like core and fucosyl branches of α-L-Fuc2,4S, α-L-Fuc4S or α-L-Fuc3,4S linked to O-3 of glucuronic acid residues. The main branches of FCS_hp and FCS_ht were monofucose, and the small amounts of di-, tri- and tetrafucose with α-1,3-linkage type were also detected. Finally, we investigated the immunomodulatory function of FCS_hp and FCS_ht in cyclophosphamide (CTX)-induced immunosuppressed mouse models. The results showed that FCS_hp and FCS_ht had beneficial effects on hematopoietic function recovery in CTX-induced bone marrow suppression mice. Notably, the α-L-Fuc2,4S was more important to the activity than α-L-Fuc3,4S. These results provided basis for developing the drugs to reduce side effects of chemotherapy.

A Study for the Access to a Semi-synthetic Regioisomer of Natural Fucosylated Chondroitin Sulfate with Fucosyl Branches on N-acetyl-Galactosamine Units

Fucosylated chondroitin sulfate (fCS) is a glycosaminoglycan found up to now exclusively in the body wall of sea cucumbers. It shows several interesting activities, with the anticoagulant and antithrombotic as the most attractive ones. Its different mechanism of action on the blood coagulation cascade with respect to heparin and the retention of its activity by oral administration make fCS a very promising anticoagulant drug candidate for heparin replacement. Nonetheless, its typically heterogeneous structure, the detection of some adverse effects and the preference for new drugs not sourced from animal tissues, explain how mandatory is to open an access to safer and less heterogeneous non-natural fCS species. Here we contribute to this aim by investigating a suitable chemical strategy to obtain a regioisomer of the natural fCS polysaccharide, with sulfated l-fucosyl branches placed at position O-6 of N-acetyl-d-galactosamine (GalNAc) units instead of O-3 of d-glucuronic acid (GlcA) ones, as in natural fCSs. This strategy is based on the structural modification of a microbial sourced chondroitin polysaccharide by regioselective insertion of fucosyl branches and sulfate groups on its polymeric structure. A preliminary in vitro evaluation of the anticoagulant activity of three of such semi-synthetic fCS analogues is also reported.

Fucoidan from sea cucumber Holothuria polii: Structural elucidation and stimulation of hematopoietic activity

The structural elucidation of polysaccharides is essential for understanding their structure-bioactivity relationship and related drug development. In this study, fucoidan (Fuc_hp) was extracted and purified from sea cucumber Holothuria polii. Its sulfate content was 39.5 ± 1.4%, and the "weight-average" molecular mass was 103.1 ± 2.8 kDa. The primary structure of Fuc_hp was clarified using a combination of acid degradation, tandem mass spectrometry, and nuclear magnetic resonance spectroscopy analysis. As a result, Fuc_hp was found to be composed of a tetrafucose repeating unit [→3-α-l-Fucp-1 → 3-α-l-Fucp2(OSO₃^-)-1 → 3-α-l-Fucp2(OSO₃^-)-1 → 3-α-l-Fucp2,4(OSO₃^-)-1→]. The stimulating hematopoiesis was further evaluated in a mouse model induced by cyclophosphamide. Based on these findings, intraperitoneally administered Fuc_hp may accelerate the recovery of white blood cells and neutrophils, in which its activity exceeded that of recombinant human granulocyte colony-stimulating factor (rhG-CSF). Meanwhile, in the background of cyclophosphamide-induced immunosuppression, treatment with Fuc_hp reduces platelet aggregation caused by CTX, so it might have the effect of reducing the risk of thrombosis. Therefore, Fuc_hp can be exploited as potentially promising stimulator of hematopoiesis in the future.

Bottom-up analysis using liquid chromatography-Fourier transform mass spectrometry to characterize fucosylated chondroitin sulfates from sea cucumbers

Fucosylated chondroitin sulfates (FCSs) from sea cucumbers have repetitive structures that exhibit minor structural differences based on the organism from which they are recovered. A detailed characterization of FCSs and their derivatives is important to establish their structure-activity relationship in the development of new anticoagulant drugs. In the current study, online hydrophilic interaction chromatography-Fourier transform mass spectrometry (FTMS) was applied to analyze the FCS oligosaccharides generated by selective degradation from four species of sea cucumbers, Isostichopus badionotus, Pearsonothuria graeffei, Holothuria mexicana and Acaudina molpadioides. These depolymerized FCS fragments were quantified and compared using the glycomics software package, GlycReSoft. The quantified fragments mainly had trisaccharide-repeating compositions and showed significant differences in fucosylation (including its sulfation) among different species of sea cucumbers. Detailed analysis of FTMS ion peaks and top-down nuclear magnetic resonance spectroscopy of native FCS polysaccharides verified the accuracy of this method. Thus, a new structural model for FCS chains from these different sea cucumbers was defined. This bottom-up approach provides rich detailed structural analysis and provides quantitative information with high accuracy and reproducibility and should be suitable for the quality control in FCSs as well as their oligosaccharides.

Recovery of high-value and scarce resources from biological wastewater treatment: Sulfated polysaccharides

Recovering materials with high value and increasing market demand from sewage and/or sludge is becoming more attractive than recovering traditional resources such as nutrients and biogas. Sulfated polysaccharides (SPs) are valuable and scarce raw materials that can only be produced from marine algae and a few types of animal tissues. This study evaluated if SPs are present in activated sludge obtained from saline sewage with a high level of sulfates present. The presence of SPs-containing extracellular polymeric substances (EPS) was confirmed and quantified for both sludge from lab-scale reactors and full-scale plants for the first time. SPs in the sludge of a lab-scale reactor operated under alternating aerobic/anoxic conditions with 500 mg/L sulfate in the influent (which is typical of Hong Kong saline sewage) reached 342.8 ± 0.3% mg/gVSS, and sludge taken from a full-scale saline wastewater treatment plant (WWTP) contained 418.1 ± 0.4% mg/gVSS of SPs. Purity of the extracted SPs was comparable to that of commercial industrial-grade products. Key bioactivities of SPs (i.e. fucoidan, carrageenan and heparin), namely anti-angiogenesis, anticoagulant and antioxidant, were confirmed after extraction and purification. Interestingly, operating conditions had a strong influence on the contents and types of SPs synthesized in sludge as well as its bioactivities. Although the detailed synthetic pathways of SPs in activated sludge remain unclear, the current study has made a first attempt to recover a high-value scarce resource from biological wastewater treatment.