Structure and pharmacological activities of a sulfated xylofucoglucuronan from the alga Spatoglossum schroederi

An acidic polysaccharide of 21 kDa, containing fucose, xylose, glucuronic acid and sulfate, accounting for 20% of the total acidic polysaccharides present in the alga Spatoglossum schroederi, was purified by ion exchange and molecular sieving chromatography. It migrated as a single component in agarose gel electrophoresis prepared in five different buffer systems with pH ranging from 2.0 to 9.0. Chemical analyses, methylation studies, degradation with glycosidases and sulfatases prepared from the mollusc Tagelus gibbus, acid hydrolysis, C-13 and H-1 NMR and infra-red spectroscopy led to the proposal of the structure of the compound and the mode of action of the enzymes. The polymer is composed of a core of beta(1-3)glucuronic acid-containing oligosaccharide of 4.5 kDa with branches at C-4 of the fucose chains alpha(1-3)-linked. The fucose is mostly substituted at C-4 with sulfate groups and at C-2 with chains of beta(1-4) xylose which, in turn is also partially sulfated. The xylofucoglucuronan has low anticoagulant and no hemorrhagic activity but, as heparin, has a high activity in stimulating the synthesis of an antithrombotic heparan sulfate from vascular endothelial cells in culture. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.