title: Scavenging of hydroxyl radical by catecholamines.
abstract: The direct effects of the four catecholamines (CATs), adrenaline (A), noradrenaline (NA), dopamine (D) and isoproterenol (I), on free radicals were investigated using the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH(•)) and hydroxyl radial (HO(•)). The CATs examined were found to inhibit the ESR signal intensity of DPPH(•) in a dose-dependent manner over the range 0.1-2.5 mmol/L in the following order: NA > A > I > D, with IC50= 0.30 ± 0.03 for noradrenaline and IC50= 0.86 ± 0.02 for dopamine. Hydroxyl radicals were produced using a Fenton reaction in the presence of the spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO), and ESR technique was applied to detect the CATs reactivity toward the radicals. The reaction rates constant (k(r)) of CATs with HO(•) were found to be in the order of 10(9)  L/mol/s, and the k(r) value for noradrenaline was the highest (k(r)= 8.4 × 10(9)  L/mol/s). The CATs examined exhibited also a strong decrease in the light emission (62-73% at 1 mmol/L concentration and 79-89% at 2 mmol/L concentration) from a Fenton-like reaction. These reactions may be relevant to the biological action of these important polyphenolic compounds.
authors.affiliation: Department of Medical History and Ethics, Pomeranian Medical University of Szczecin, Poland.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Kładna
authors.forename: Paweł
authors.initials: P
authors.lastname: Berczyński
authors.forename: Irena
authors.initials: I
authors.lastname: Kruk
authors.forename: Teresa
authors.initials: T
authors.lastname: Michalska
authors.forename: Hassan Y
authors.initials: HY
authors.lastname: Aboul-Enein
mesh_terms: D001713:Biphenyl Compounds / Q000737:chemistry; D002395:Catecholamines / Q000737:chemistry* / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004578:Electron Spin Resonance Spectroscopy; D016166:Free Radical Scavengers / Q000737:chemistry* / Q000494:pharmacology; D017665:Hydroxyl Radical / Q000737:chemistry*; D020128:Inhibitory Concentration 50; D010851:Picrates / Q000737:chemistry
chemical_list: D001713:Biphenyl Compounds; D002395:Catecholamines; D016166:Free Radical Scavengers; D010851:Picrates; D017665:Hydroxyl Radical; C004931:1,1-diphenyl-2-picrylhydrazyl