Preparation of a low-molecular weight fraction by free radical depolymerization of the sulfated galactan from Schizymenia binderi (Gigartinales, Rhodophyta) and its anticoagulant activity

Depolymerization of the sulfated galactan from Schizymenia binderi with H2O2 in the presence of copper (II) acetate afforded a homogeneous fraction (MW 8500) in 50% yield. Alkylation and NMR spectroscopy analysis of this fraction indicated the presence of an agaran–carrageenan hybrid polysaccharide composed of 3-linked β-d-galactopyranosyl residue partially sulfated at position O-2 and 4-linked α-d-galactopyranosyl and α-l-galactopyranosyl residues mainly sulfated at position O-3 and glycosylated at position O-2. Discreet anticoagulant activity, similar to that of the native polysaccharide was found in the derivative obtained by sulfation of this fraction.