Structural and hemostatic activities of a sulfated galactofucan from the brown alga Spatoglossum schroederi. An ideal antithrombotic agent?

• Published in: The Journal of biological chemistry 2005-12, Vol.280 (50), p.41278-41288
• Main Authors: Rocha, Hugo A O, Moraes, Fábio A, Trindade, Edvaldo S, Franco, Célia R C, Torquato, Ricardo J S, Veiga, Silvio S, Valente, Ana P, Mourão, Paulo A S, Leite, Edda L, Nader, Helena B, Dietrich, Carl P
• Format: Article
• Language: English
• Subjects: Acetone - chemistry; Acetone - pharmacology; Animals; Anticoagulants - chemistry; Anticoagulants - pharmacology; Carbohydrate Sequence; Cattle; Chromatography; Chromatography, Ion Exchange; Culture Media, Conditioned - pharmacology; Dose-Response Relationship, Drug; Electrophoresis, Agar Gel; Endothelial Cells - cytology; Endothelial Cells - metabolism; Factor Xa - chemistry; Fibrinolytic Agents - chemistry; Fibrinolytic Agents - pharmacology; Fucose - chemistry; Furans - chemistry; Galactose - chemistry; Glucuronic Acid - chemistry; Hemostasis; Heparin - chemistry; Heparitin Sulfate - chemistry; Humans; Magnetic Resonance Spectroscopy; Methylation; Molecular Sequence Data; Oligosaccharides - chemistry; Phaeophyceae - metabolism; Polysaccharides - chemistry; Rats; Spatoglossum schroederi; Sulfur - chemistry; Sulfuric Acid Esters - chemistry; Thymidine - chemistry; Time Factors; Xylose - chemistry
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M501124200

The brown alga Spatoglossum schroederi contains three fractions of sulfated polysaccharides. One of them was purified by acetone fractionation, ion exchange, and molecular sieving chromatography. It has a molecular size of 21.5 kDa and contains fucose, xylose, galactose, and sulfate in a molar ratio of 1.0:0.5:2.0:2.0 and contains trace amounts of glucuronic acid. Chemical analyses, methylation studies, and NMR spectroscopy showed that the polysaccharide has a unique structure, composed of a central core formed mainly by 4-linked beta-galactose units, partially sulfated at the 3-O position. Approximately 25% of these units contain branches of oligosaccharides (mostly tetrasaccharides) composed of 3-sulfated, 4-linked alpha-fucose and one or two nonsulfated, 4-linked beta-xylose units at the reducing and nonreducing end, respectively. This sulfated galactofucan showed no anticoagulant activity on several "in vitro" assays. Nevertheless, it had a potent antithrombotic activity on an animal model of experimental venous thrombosis. This effect is time-dependent, reaching the maximum 8 h after its administration compared with the more transient action of heparin. The effect was not observed with the desulfated molecule. Furthermore, the sulfated galactofucan was 2-fold more potent than heparin in stimulating the synthesis of an antithrombotic heparan sulfate by endothelial cells. Again, this action was also abolished by desulfation of the polysaccharide. Because this sulfated galactofucan has no anticoagulant activity but strongly stimulates the synthesis of heparan sulfate by endothelial cells, we suggested that this last effect may be related to the "in vivo" antithrombotic activity of this polysaccharide. In this case the highly sulfated heparan sulfate produced by the endothelial cells is in fact the antithrombotic agent. Our results suggested that this sulfated galactofucan may have a potential application as an antithrombotic drug.