title: Nitroxides protect against peroxynitrite-induced nitration and oxidation.
abstract: Nitroxides are promising compounds for prevention of undesired protein modifications. The aim of this study was to compare the efficiency of 11 nitroxides, derivatives of 2,2,6,6-tetramethylpiperidine-1-oxide (TEMPO) and 2,2,5,5-tetramethylpirrolidine-1-oxyl (PROXYL) in prevention of nitration and oxidation of model compounds and human serum albumin (HSA). Most nitroxides were very efficient in preventing loss of fluorescein fluorescence induced by peroxynitrite (PN) (IC50 in the nanomolar range) and preventing HSA nitration. The loss of fluorescein fluorescence was demonstrated to be due to nitration. Nitroxides were more effective in prevention nitration than oxidation reactions. They showed a concentration window for preventing dihydrorhodamine (DHR) 123 oxidation but exerted a prooxidant effect at both high and low concentrations. No prooxidant effect of nitroxides was seen in prevention of DHR123 oxidation induced by SIN-1. In all essays hydrophobic nitroxides (especially 4-nonylamido-TEMPO and 3-carbamolyl-dehydroPROXYL) showed the lowest efficiency. An exception was the prevention of thiol group oxidation by PN and SIN-1 where hydrophobic nitroxides were the most effective, apparently due to binding to the protein. Nitroxides showed low toxicity to MCF-7 cells. Most nitroxides, except for the most hydrophobic ones, protected cells from the cytotoxic action of SIN-1 and SIN-1-induced protein nitration. These results point to potential usefulness of nitroxides for prevention of PN-induced oxidation and, especially, nitration.
authors.affiliation: Department of Biochemistry and Cell Biology, Faculty of Biology and Agriculture, University of Rzeszów, Rzeszów, Poland. Electronic address: isadowska@poczta.fm.
authors.forename: Izabela
authors.initials: I
authors.lastname: Sadowska-Bartosz
authors.affiliation: Department of Molecular Biophysics, Faculty of Biology and Environmental Protection, University of Łódź, Łódź, Poland.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Gajewska
authors.affiliation: Department of Organic Chemistry, Faculty of Chemistry, University of Łódź, Łódź, Poland.
authors.forename: Janusz
authors.initials: J
authors.lastname: Skolimowski
authors.affiliation: Department of Industrial Microbiology and Biotechnology, Institute of Microbiology, Biotechnology and Immunology, Faculty of Biology and Environmental Protection, University of Łódź, Łódź, Poland.
authors.forename: Rafał
authors.initials: R
authors.lastname: Szewczyk
authors.affiliation: Department of Biochemistry and Cell Biology, Faculty of Biology and Agriculture, University of Rzeszów, Rzeszów, Poland; Department of Molecular Biophysics, Faculty of Biology and Environmental Protection, University of Łódź, Łódź, Poland.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Bartosz
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D006801:Humans; D061986:MCF-7 Cells; D009566:Nitrates / Q000378:metabolism*; D009589:Nitrogen Oxides / Q000494:pharmacology*; D010084:Oxidation-Reduction; D030421:Peroxynitrous Acid / Q000494:pharmacology*; D026361:Reactive Nitrogen Species / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013438:Sulfhydryl Compounds / Q000737:chemistry; D053719:Tandem Mass Spectrometry
chemical_list: D009566:Nitrates; D009589:Nitrogen Oxides; D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species; D013438:Sulfhydryl Compounds; D030421:Peroxynitrous Acid
keywords: Dihydrorhodamine 123; Fluorescein; Human serum albumin; MCF-7 cells; Nitration; Nitroxides; Oxidation; Peroxynitrite; SIN-1