title: Free radical generation during chemical depolymerization of heparin.
abstract: Low-molecular weight heparins (LMWHs), as compared with unfractionated heparin (UFH), present superior bioavailability, much longer plasma half-life, and lower incidence of side effects. For these reasons, over the past two decades LMWHs have become the drugs of choice for the treatment of deep venous thrombosis, pulmonary embolism, arterial thrombosis, and unstable angina. Furthermore, their use in acute ischemic stroke is currently under study. LMWHs are obtained by UFH depolymerization, which can be performed using various methods, including nitrous acid depolymerization, cleavage by beta-elimination of benzyl ester, enzymatic depolymerization, and peroxyl radical-dependent depolymerization. This article addresses the chemical depolymerization, obtained by free radical attack (mainly hydroxyl radical), of heparin. The electron spin resonance (ESR) spectroscopy, coupled to the spin trapping technique, was employed to study this reaction. Free radical-mediated heparin depolymerization was performed under different chemical conditions. The final products of the reactions were purified and classified on the basis of their molecular weight and other characteristics. The level of heparin fragmentation was different depending on the type of depolymerization reaction used. Moreover, the level of reproducibility and the resulting radical species were different for every type of reaction performed.
authors.affiliation: Department of Biomedical Sciences, University of Modena and Reggio Emilia, Modena 41100, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Rota
authors.forename: Lino
authors.initials: L
authors.lastname: Liverani
authors.forename: Franco
authors.initials: F
authors.lastname: Spelta
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Mascellani
authors.forename: Aldo
authors.initials: A
authors.lastname: Tomasi
authors.forename: Anna
authors.initials: A
authors.lastname: Iannone
authors.forename: Elena
authors.initials: E
authors.lastname: Vismara
mesh_terms: D002384:Catalysis; D003300:Copper / Q000737:chemistry; D003497:Cyclic N-Oxides; D004187:Disaccharides / Q000032:analysis; D004578:Electron Spin Resonance Spectroscopy; D005296:Ferrous Compounds / Q000737:chemistry; D005609:Free Radicals / Q000737:chemistry*; D006493:Heparin / Q000737:chemistry*; D006495:Heparin, Low-Molecular-Weight / Q000138:chemical synthesis* / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration; D017665:Hydroxyl Radical / Q000737:chemistry; D009589:Nitrogen Oxides; D015203:Reproducibility of Results; D013113:Spin Labels
chemical_list: D003497:Cyclic N-Oxides; D004187:Disaccharides; D005296:Ferrous Compounds; D005609:Free Radicals; D006495:Heparin, Low-Molecular-Weight; D009589:Nitrogen Oxides; D013113:Spin Labels; D017665:Hydroxyl Radical; C020748:ferrous sulfate; C029217:phenyl-N-tert-butylnitrone; C017245:5,5-dimethyl-1-pyrroline-1-oxide; D003300:Copper; D006493:Heparin