title: Antioxidant/prooxidant effects of α-tocopherol, quercetin and isorhamnetin on linoleic acid peroxidation induced by Cu(II) and H2O2.
abstract: The peroxidation of linoleic acid (LA) in the presence of copper(II) (Cu(II)) ions alone and with α-tocopherol (α-TocH) was investigated in aerated and incubated emulsions at 37 °C and pH 7. Additionally, the effects of quercetin (QR) and its O-methylated derivative, isorhamnetin (IR), as potential antioxidant protectors were studied in the (Cu(II) + TocH)-induced LA peroxidation system. Cu(II)-induced LA peroxidation followed pseudo-first-order kinetics with respect to primary (hydroperoxides) and secondary (aldehydes- and ketones-like) oxidation products, which were determined by ferric thiocyanate and thiobarbituric acid-reactive substances methods, respectively. As opposed to the concentration-dependent (at 0.6 and 10.0 µM) prooxidative action of α-TocH in the absence of QR and IR, the latter two compounds showed antioxidant effect over TocH. The peroxidation of LA in the presence of Cu(II)-H(2)O(2) combination alone and with TocH, QR and IR were also investigated in aerated and incubated emulsions, where the latter three compounds exhibited antioxidant effects.
authors.affiliation: Chemistry Department, Science and Arts Faculty, Yildiz Technical University , Esenler, Istanbul , Turkey and.
authors.forename: Temelkan
authors.initials: T
authors.lastname: Bakır
authors.forename: Inci
authors.initials: I
authors.lastname: Sönmezoğlu
authors.forename: Filiz
authors.initials: F
authors.lastname: Imer
authors.forename: Reşat
authors.initials: R
authors.lastname: Apak
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D003300:Copper; D006861:Hydrogen Peroxide; D019787:Linoleic Acid / Q000378:metabolism*; D015227:Lipid Peroxidation / Q000187:drug effects*; D016877:Oxidants / Q000494:pharmacology*; D011794:Quercetin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D024502:alpha-Tocopherol / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; D016877:Oxidants; C047368:3-methylquercetin; D003300:Copper; D011794:Quercetin; D019787:Linoleic Acid; D006861:Hydrogen Peroxide; D024502:alpha-Tocopherol