title: High-molar-mass hyaluronan behavior during testing its radical scavenging capacity in organic and aqueous media: effects of the presence of manganese(II) ions.
abstract: This study compares the radical scavenging capacity of high-molar-mass hyaluronan (HA) using standardized methods applying 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals and 2,2'-azinobis[3-ethylbenzthiazoline sulfonate] (ABTS) radical cations as oxidants. Additionally, spin-trapping technique combined with electron paramagnetic resonance (EPR) was used to evaluate the ability of HA to scavenge reactive radicals. The thermal decomposition of K2S2O8 in pure H2O or in a H2O/dimethyl sulfoxide (DMSO) mixture at 333 K was used as a source of reactive paramagnetic species. We found that HA does not exhibit radical-scavenging activity when DPPH radicals or ABTS(.+) radical cations are used as oxidant, but that HA is an effective radical scavenger at low concentrations, if the oxidation reactions are initiated by the decomposition of K2S2O8. At higher HA concentrations, a more complex behavior and prooxidant HA action was observed. The influence of Mn(II) ions on the reaction mechanisms of radical generation and termination in the K2S2O8/H2O/DMSO system in the presence of HA was studied in detail.
authors.affiliation: Institute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology, Slovak University of Technology, SK-81237 Bratislava. peter.rapta@stuba.sk
authors.forename: Peter
authors.initials: P
authors.lastname: Rapta
authors.forename: Katarína
authors.initials: K
authors.lastname: Valachová
authors.forename: Peter
authors.initials: P
authors.lastname: Gemeiner
authors.forename: Ladislav
authors.initials: L
authors.lastname: Soltés
mesh_terms: D052160:Benzothiazoles / Q000737:chemistry; D001713:Biphenyl Compounds / Q000737:chemistry; D004121:Dimethyl Sulfoxide / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D016166:Free Radical Scavengers / Q000737:chemistry*; D006820:Hyaluronic Acid / Q000737:chemistry*; D007287:Inorganic Chemicals / Q000737:chemistry; D008345:Manganese / Q000737:chemistry*; D010851:Picrates / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D013451:Sulfonic Acids / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D052160:Benzothiazoles; D001713:Biphenyl Compounds; D016166:Free Radical Scavengers; D007287:Inorganic Chemicals; D010851:Picrates; D013451:Sulfonic Acids; D014867:Water; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; D008345:Manganese; D006820:Hyaluronic Acid; C004931:1,1-diphenyl-2-picrylhydrazyl; D004121:Dimethyl Sulfoxide