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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-Fuc 2S -(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 -GalNAc 4S6S -β(1,4)- D -GlcA}, and each GlcA residue was branched with Fuc 2S4S . 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 Fuc 3S4S showed that in oligosaccharides with lower degrees of polymerization, such as octasaccharides, Fuc 2S4S 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.

The elucidation of the precise structure of fucan sulfate is essential for understanding the structure-activity relationship and promoting potential biomedical applications. In this work, the structure of a distinct fucan sulfate fraction V (PmFS in Ref 15 and FSV in Ref 16 → PFV) from Pattalus mollis was investigated using an oligosaccharide mapping approach. Six size-homogeneous fractions were purified from the mild acid hydrolyzed PFV and identified as fucitols, disaccharides and trisaccharides by 1D/2D NMR and MS analysis. Significantly, the sulfation pattern, glycosidic linkages, and sequences of all the oligosaccharides were unambiguously identified. The common 2-desulfation of the reducing end residue of the oligosaccharides was observed. Overall, the backbone of PFV was composed of L-Fuc 2S (major) and L-Fuc 3S (minor) linked by α1,4 glycosidic bonds. Importantly, the branches contain both monosaccharide and disaccharide linked to the backbone by α1,3 glycosidic linkages. Thus, the tentative structure of natural PFV was shown to be {-(R-α1,3)-L-Fuc 2S -α1,4-(L-Fuc 2S/3S -α1,4) x -} n , where R is L-Fuc (2S)4S -α1,3/4-L-Fuc 4S(0S) - or L-Fuc (2S)4S -. Our results provide insight into the heterogeneous structure of the fucan sulfate found in sea cucumbers. Additionally, PFV and its fractions showed strong anticoagulant and anti-iXase activities, which may be related to the distinct structure of PFV., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Fucan sulfates from echinoderm possess characteristic structures and various biological activities. Herein, comprehensive methods including enzymolysis, ion-exchange chromatography and size exclusion chromatography lead to the purification of five fucan sulfates (FSI, FSII, FSIII, FSIV, FSV) from the sea cucumber Pattalus mollis. Chemical composition analysis showed that they were all composed of l-fucose. Their sulfate content was determined by a conductimetric method. The molecular weight (Mw) of FSI, FSII, FSIII, FSIV and FSV were measured as 238.3 kDa, 81.0 kDa, 82.0 kDa, 23.2 kDa and 6.12 kDa, respectively. Detailed NMR spectroscopic analysis revealed that the structural sequence of FSI and FSII was →3)-l-Fuc S -α(1→, where Fuc S were Fuc 2S4S (10%), Fuc 2S (44%), Fuc 0S (10%), Fuc 4S (36%), that of FSIII was →4)-l-Fuc 2S -(α1 → 4)-l-Fuc 2S -(α1 → 4)-l-Fuc 0S/3S -(α1→, where Fuc 0S and Fuc 3S were in equal molar, and that FSIV was →4)-l-Fuc 2S3S -(α1 → 4)-l-Fuc 2S3S -(α1 → 4)-l-Fuc 2S -(α1→4)-l-Fuc 2S -(α1 → 4)-l-Fuc 2S -(α1 → 4)-l-Fuc 2S -(α1 → . This is the first report that such a diversity of fucan sulfates were obtained from the same sea cucumber species. Biological activity showed that FSI, FSII, FSIII and FSIV exhibited potent anticoagulant by prolonging the APTT. Among them, FSII, FSIII and FSIV showed the similar potency, while FSI owned the strongest. Structure-activity relationships analysis showed that molecular weight and sulfation degree should be the crucial factors for the activity., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Marine sulfated polysaccharides have aroused widespread concern for their various structures and bioactivities. Peroxide depolymerization is a common strategy in analysis of structures and structure-activity relationships of polysaccharides. However, confirming the depolymerization process and exact structures of the degradation products is still a considerable challenge. This study reported the structures of a fucan sulfate (FS) from sea cucumber Stichopus herrmanni and its depolymerized products (dFS) prepared by peroxide degradation. The FS was elucidated with a highly regular structure, {-3)-L-Fuc 2S -(α1-} n . Structure analysis of oligosaccharides purified from dFS suggested that peroxide degradation involved in cleavage of glycosidic bonds and oxidative modification of reducing end of sugar residue, while no break in sugar ring was observed. Both FS and series of dFSs exhibited significant anticoagulant activities due to their anti-thrombin effects in presence of heparin cofactor II and their potencies were related to their molecular sizes, dFS with ∼ 20 kDa showed the strongest activity., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Sulfated polysaccharides from sea cucumbers possess distinct chemical structure and various biological activities. Herein, three types of polysaccharides were isolated and purified from Pattalus mollis , and their structures and bioactivities were analyzed. The fucosylated glycosaminoglycan (PmFG) had a CS-like backbone composed of the repeating units of {-4-d-GlcA-β-1,3-d-GalNAc 4S6S -β-1-}, and branches of a sulfated α-l-Fuc (including Fuc 2S4S , Fuc 3S4S and Fuc 4S with a molar ratio of 2:2.5:1) linked to O-3 of each d-GlcA. The fucan sulfate (PmFS) had a backbone consisting of a repetitively linked unit {-4-l-Fuc 2S -α-1-}, and interestingly, every trisaccharide unit in its backbone was branched with a sulfated α-l-Fuc (Fuc 4S or Fuc 3S with a molar ratio of 4:1). Apart from the sulfated polysaccharides, two neutral glycans (PmNG-1 & -2) differing in molecular weight were also obtained and their structures were similar to animal glycogen. Anticoagulant assays indicated that PmFG and PmFS possessed strong APTT prolonging and intrinsic factor Xase inhibition activities, and the sulfated α-l-Fuc branches might contribute to the anticoagulant and anti-FXase activities of both PmFG and PmFS.

Sulfated polysaccharides such as fucosylated glycosaminoglycan and fucan sulfate from echinoderm possess complex chemical structure and various biological activities. The two sulfated polysaccharides were purified from the low-value sea cucumber Holothuria coluber. Their physicochemical properties and chemical structures were analyzed and characterized by chemical and instrumental methods. Structural analysis clarified that the sea cucumber fucosylated glycosaminoglycan contains a chondroitin sulfate-like backbone and fucosyl branches with four various sulfation patterns. The fucan sulfate with molecular weight of 64.6 kDa comprises a central core of regular α(1 → 4)-linked tetrasaccharide repeating units, each of which is linked by a 4-O-sulfated fucose residue. Anticoagulant assays indicated that these sulfated polysaccharides possessed strong APTT prolonging activities and intrinsic factor Xase inhibitory activities, both of which decreased with the reduction of their molecular weights. Our results expand knowledge on the structural types of sulfated polysaccharides from sea cucumbers and further illustrate their functionality., (Copyright © 2018 Elsevier B.V. All rights reserved.)

A fucan sulfate was isolated and purified from the sea cucumber Holothuria albiventer by papain enzymolysis, alkaline hydrolysis and ion-exchange chromatography. The water-soluble polysaccharide had high molecular weight and contained fucose and sulfate in a molar ratio of about 1:0.83. Methylation analysis of the native polysaccharide indicated that its glycosidic linkages and sulfate substituents might be at O-3 or O-3, 4 or O-2, 3, or O-2, 3, 4 positions. FT-IR and 2D NMR spectroscopies further revealed that the fucan sulfate is characteristically composed of a regular α (1 → 3) linked hexasaccharide repeating unit which is substituted with sulfate esters in a distinctive pattern. Anticoagulant properties of the fucan sulfate and its depolymerized product were assessed in vitro in comparison with a low-molecular-weight heparin. The fucan sulfate exhibits strong APTT and TT prolonging activities and intrinsic factor Xase inhibitory activity, and its molecular size seemed to be required for these activities., (Copyright © 2018 Elsevier Ltd. All rights reserved.)