Aromatic hydroxylation in PBN spin trapping by hydroxyl radicals and cytochrome P-450

Citation
La. Reinke et al., Aromatic hydroxylation in PBN spin trapping by hydroxyl radicals and cytochrome P-450, FREE RAD B, 28(3), 2000, pp. 345-350
Citations number
24
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Biochemistry & Biophysics
Journal title
FREE RADICAL BIOLOGY AND MEDICINE
ISSN journal
0891-5849 → ACNP
Volume
28
Issue
3
Year of publication
2000
Pages
345 - 350
Database
ISI
SICI code
0891-5849(20000201)28:3<345:AHIPST>2.0.ZU;2-1
Abstract
Phenyl N-tert-butylnitrone (PBN) is widely used as a spin trapping agent, b ut is not useful detecting hydroxyl radicals because the resulting spin add uct is unstable. However, hydroxyl radicals could attack the phenyl ring to form stable phenolic products with no electron paramagnetic resonance sign al, and this possibility was investigated in the present studies. When PEN was added to a Fenton reaction system composed of 25 mM H2O2 and 0.1 mM FeS O4, 4-hydroxyPBN was the primary product detected, and benzoic acid was a m inor product. When the Fe2+ concentration was increased to 1.0 mM, 4-hydrox yPBN concentrations increased dramatically, and smaller amounts of benzoic acid and 2-hydroxpPBN were also formed. Although PEN is extensively metabol ized after administration to animals, its metabolites have not been identif ied. When PEN was incubated with rat liver microsomes and a reduced nicotin amide adenine dinculeotide phosphate (NADPH)-generating system, 4-hydroxyPB N was the only metabolite detected. When PEN was given to rats, both free a nd conjugated 4-hydroxyPBN were readily detected in liver extracts, bile, u rine, and plasma. Because 4-hydroxyPBN is the major metabolite of PEN and c irculates in body fluids, it may contribute to the pharmacological properti es of PEN. But 4-hydroxyPBN formation cannot be used to demonstrate hydroxy l radical formation in vivo because of its enzymatic formation. (C) 2000 El sevier Science Inc.