title: Hemin/nitrite/H2O2 induces brain homogenate oxidation and nitration: effects of some flavonoids.
abstract: Oxidative injury has been implicated in the pathogenesis of numerous neurodegenerative diseases. Recently, it has been found that with the existence of hydrogen peroxide and nitrite, hemin catalyzes protein nitration. We hypothesize under certain pathological conditions, hemin catalyzed protein nitration may happen in the brain. In this paper, the effects of three flavonoids, i.e. quercetin, catachin and baicalein on hemin/nitrite/H2O2 induced brain homogenate oxidation and nitration were studied. The results showed that hemin/nitrite/H2O2 system could effectively induce brain homogenate protein oxidation and nitration. Quercetin, catachin and baicalein dose-dependently inhibited hemin/nitrite/H2O2 system-induced protein nitration in a dose-dependent manner, the inhibition of protein nitration was in the order of quercetin>catachin>baicalein. These compounds also inhibited hemin/H2O2 system-induced lipid peroxidation, the inhibition order was baicalein >quercetin>catachin. However, these flavonoids showed marginal effect on hemin/nitrite/H2O2 system caused protein oxidation and thiol oxidation. The inhibition activities of flavonoids on hemin/nitrite/H2O2 system-induced protein nitration may closely relate to their radical scavenging activities, since the inhibition order of protein nitration is the same as the radical scavenging order. These results indicate hemin/nitrite/H2O2 system induces different types of oxidative assault on bio-molecules. Flavonoids could act as antioxidants inhibiting ROS and RNS caused brain damage.
authors.affiliation: Department of Chemistry, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, PR China.
authors.forename: Yuling
authors.initials: Y
authors.lastname: Zhao
authors.forename: Zhonghong
authors.initials: Z
authors.lastname: Gao
authors.forename: Hailing
authors.initials: H
authors.lastname: Li
authors.forename: Huibi
authors.initials: H
authors.lastname: Xu
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D002392:Catechin / Q000494:pharmacology; D044950:Flavanones / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology*; D016166:Free Radical Scavengers / Q000494:pharmacology; D006427:Hemin / Q000494:pharmacology*; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D015227:Lipid Peroxidation / Q000187:drug effects*; D009573:Nitrites / Q000494:pharmacology*; D015538:Nitrosation / Q000187:drug effects; D016877:Oxidants / Q000494:pharmacology; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D011794:Quercetin / Q000494:pharmacology; D051381:Rats; D026361:Reactive Nitrogen Species / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D044950:Flavanones; D005419:Flavonoids; D016166:Free Radical Scavengers; D009573:Nitrites; D016877:Oxidants; D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species; C006680:baicalein; D006427:Hemin; D002392:Catechin; D011794:Quercetin; D006861:Hydrogen Peroxide; D010100:Oxygen