Characterization of di- and monosulfated, unsaturated heparin disaccharides with terminal N-sulfated 1,6-anhydro-β-d-glucosamine or N-sulfated 1,6-anhydro-β-d-mannosamine residues

Modified heparin disaccharides were obtained by the alkaline treatment of a solution containing the disulfated heparin disaccharide ΔHexA-α-(1→4)-d-GlcNSO3,6SO3. Their structures were characterized by one- and two-dimensional NMR spectroscopy: ΔHexA-α-(1→4)-1,6-anhydro-GlcNSO3, ΔHexA-α-(1→4)-1,6-anhydro-ManNSO3 and ΔHexA-α-(1→4)-ManNSO3,6OSO3. NMR spectroscopy, in combination with HPLC, provided the composition of the mixture. Characteristic NMR signals of the disaccharides were identified, even at low levels, in a high field of 1H–13C correlation NMR spectra (HSQC) of a low molecular weight heparin (LMWH) obtained by β-elimination (alkaline hydrolysis) of heparin benzyl ester, providing a more complete structural profile of this class of compounds.