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

Abstract

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 schröederi, 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, 13C and 1H 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 β(1–3)glucuronic acid-containing oligosaccharide of 4.5 kDa with branches at C 4 of the fucose chains α(1–3)-linked. The fucose is mostly substituted at C 4 with sulfate groups and at C 2 with chains of β(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.