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

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 galacto-fucan 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.Universidade Federal de São Paulo, Escola Paulista Med, Dept Bioquim, BR-04044020 São Paulo, BrazilUniv Fed Rio Grande Norte, Dept Bioquim, Lab Biotecnol Polimeros Nat BIOPOL, BR-59072970 Natal, RN, BrazilUniv Fed Parana, Dept Biol Celular, BR-83531990 Curitiba, Parana, BrazilUniv Fed Rio de Janeiro, Inst Bioquim Med, BR-21941590 Rio de Janeiro, BrazilUniv Fed Rio de Janeiro, Univ Hosp, BR-21941590 Rio de Janeiro, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Bioquim, BR-04044020 São Paulo, BrazilWeb of Scienc