Kinetic study on ESR signal decay of nitroxyl radicals,potent redox probes for in vivo ESR spectroscopy,caused by reactive oxygen species |
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| Institution: | 1. Department of Hematology, Xinqiao Hospital, The Third Military Medical University, Chongqing 400037, China;2. Department of Hematology-oncology, Chongqing Cancer Institute/Hospital, Chongqing 400030, China;3. Department of Pathology, Chongqing Cancer Institute/Hospital, Chongqing 400030, China;4. Institute of Toxicology, School of Preventive Medicine, The Third Military Medical University, Chongqing 400038, China;1. State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Jiangsu, Nanjing 210023, PR China;2. Key Laboratory of Surficial Geochemistry, Ministry of Education, School of Earth Sciences and Engineering, Hydrosciences Department, Nanjing University, Nanjing 210023, PR China;1. Department of Pharmaceutical Chemistry, Nizhny Novgorod State Medical Academy, Minin sq., 10/1, 603600 Nizhny Novgorod, Russian Federation;2. Lobachevsky State University of Nizhni Novgorod, 23 Gagarin Avenue, 603950 GSP-43, Russian Federation;3. A.E. Arbusov Institute of Organic and Physical Chemistry, Kazan Scientific Center, Russian Academy of Sciences, Arbuzov str. 8, 420088 Kazan, Russian Federation;4. G.A Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, 49 Tropinina str., 603137 GSP-445, Russian Federation;1. ETH Zurich, Laboratory of Physical Chemistry, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland;2. ETH Zurich Laboratory of Organic Chemistry, Vladimir-Prelog-Weg 3, 8093 Zurich, Switzerland |
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| Abstract: | The effect of the chemical structure of nitroxyl spin probes on the rate at which ESR signals are lost in the presence of reactive oxygen species (ROS) was examined. When the spin probes were reacted with either hydroxyl radical ( OH) or superoxide anion radical (O2−) in the presence of cysteine or NADH, the probes lost ESR signal depending on both their ring structure and substituents. Pyrrolidine nitroxyl probes were relatively resistant to the signal decay caused by O2− with cysteine/NADH. Signal decay rates for these reactions correlated with reported redox potentials of the nitroxyl/oxoammonium couple of spin probes, suggesting that the signal decay mechanism in both cases involves the oxidation of a nitroxyl group. The apparent rate constants of the reactions between the spin probe and OH and between the spin probe and O2− in the presence of cysteine were estimated using mannitol and superoxide dismutase (SOD), respectively, as competitive standards. The rate constants for spin probes and OH were in the order of 109 M−1 s−1, much higher than those for the probes and O2− in the presence of cysteine (103–104 M−1 s−1). These basic data are useful for the measurement of OH and O2− in living animals by in vivo ESR spectroscopy. |
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