Preparation and anticoagulant activity of fully O-sulphonated glycosaminoglycans

Glycosaminoglycans including dermatan sulphate, hyaluronan, heparan sulphat e and heparin were chemically modified by O-sulphonation. By altering the r eaction conditions, products having a different degree of O-sulphonation co uld be obtained. Glycosaminoglycan derivatives were prepared having no free hydroxyl groups, with sulphoester group/disaccharide unit ratios of 4.0 fo r dermatan sulphate and hyaluronan, and sulphoester and sulphamide group/di saccharide unit ratios of 4.22 and 4.88 for heparan sulphate and heparin, r espectively. H-1 NMR spectroscopy showed that the fully O-sulphonated hyalu ronan derivative had a glucuronate residue with an altered conformation. Si nce glycosaminiglycans and their derivatives are often used as anticoagulan t/antithrombotic agents, their anti-amidolytic activities were determined. The anti-factor IIa activity of fully O-sulphonated dermatan sulphate, hyal uronan and heparan sulphate ranged from 40 to 80 units/mg, while no anti-fa ctor Xa activity of the fully O-sulphonated glycosaminoglycans was detected . These values are lower than those reported for low-molecular-weight hepar ins and are consistent with the requirement of an antithrombin III pentasac charide binding site for anti-factor Xa activity. Interestingly, the anti-f actor Xa of heparin is lost by chemical O-sulphonation. (C) 1999 Elsevier S cience B.V. All rights reserved.