title: Hyaluronan degradation by copper(II) chloride and ascorbate: rotational viscometric, EPR spin-trapping, and MALDI-TOF mass spectrometric investigations.
abstract: The degradation of high-molar-mass hyaluronan (HA) by copper(II) chloride and ascorbate was studied by means of rotational viscometry. It was found that even small amounts of CuCl(2) present in the oxidative system led to the pronounced degradation of HA, reflected in a rapid decrease of the dynamic viscosity of the biopolymer solution. Such degradation was induced by free radicals generated in elevated amounts in the presence of copper ions. Electron paramagnetic resonance investigations performed on a model oxidative system containing Cu(II) and ascorbic acid proved the formation of relatively stable ascorbate anion radicals resulting from the reaction of ascorbic acid with hydroxyl radicals. In this way, by scavenging the hydroxyl radicals, ascorbic acid protected HA from their degradative action. Matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry was applied to analyze the degraded HA. The results showed that only regular fragmentation of hyaluronan occurred using the mentioned oxidative system that led to the formation of HA oligomers with unaffected primary chemical structure.
authors.affiliation: Institute of Experimental Pharmacology, Slovak Academy of Sciences, SK-84104 Bratislava, Slovakia. ladislav.soltes@savba.sk
authors.forename: Ladislav
authors.initials: L
authors.lastname: Soltés
authors.forename: Monika
authors.initials: M
authors.lastname: Stankovská
authors.forename: Vlasta
authors.initials: V
authors.lastname: Brezová
authors.forename: Juergen
authors.initials: J
authors.lastname: Schiller
authors.forename: Juergen
authors.initials: J
authors.lastname: Arnhold
authors.forename: Grigorij
authors.initials: G
authors.lastname: Kogan
authors.forename: Peter
authors.initials: P
authors.lastname: Gemeiner
mesh_terms: D001205:Ascorbic Acid / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D005609:Free Radicals / Q000737:chemistry; D006820:Hyaluronic Acid / Q000737:chemistry*; D008970:Molecular Weight; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D019097:Spin Trapping / Q000379:methods; D014783:Viscosity
chemical_list: D005609:Free Radicals; D003300:Copper; D006820:Hyaluronic Acid; D001205:Ascorbic Acid; C029892:cupric chloride