Oxidation of aqueous bromide ions by hydroxyl radicals. Pulse radiolytic investigation

Zehavi, Dov; Rabani, Joseph

doi:10.1021/j100647a006

Cited by 249 publications

(175 citation statements)

References 2 publications

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“…This is likely due to competition of several sites of the spin trap for the reaction with hydroxyl radical, the nitrone function playing a minor part. [51] , respectively, close to diffusion-controlled rates. This selectivity of Mito-and CD-derived spin traps towards superoxide could be of interest to discriminate between superoxide and hydroxyl formation in biological systems or cells since it makes a control incubation with SOD unnecessary.…”

Section: Discussionsupporting

confidence: 51%

Metabolic stability of superoxide adducts derived from newly developed cyclic nitrone spin traps

Bézière

Hardy

Poulhès

et al. 2014

Free Radical Biology and Medicine

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Reactive oxygen species (ROS) are by-products of aerobic metabolism involved in the onset and evolution of various pathological conditions. Among them, superoxide radical is of special interest as the origin of several damaging species such as H 2 O 2 , hydroxyl radical, or peroxynitrite (ONOO -). Spin trapping coupled with ESR is a method of choice to characterize these species in chemical and biological systems and the metabolic stability of the spin adducts derived from reaction of superoxide and hydroxyl radicals with nitrones is the main limit to the in vivo application of the method. Recently, new cyclic nitrones bearing a triphenylphosphonium or cyclodextrin moiety have been synthesized and their spin adducts demonstrated increased stability in buffer. In the present manuscript, we studied the stability of the superoxide adducts of four new cyclic nitrones in the presence of liver subcellular fractions and biologically relevant reductants using an original set up combining a stoppedflow device and an ESR spectrometer. The kinetics of disappearance of the spin adducts were analyzed using an appropriate simulation program. Our results highlight the interest of new spin trapping agents CD-DEPMPO and CD-DIPPMPO for specific detection of superoxide with high stability of the superoxide adducts in the presence of liver microsomes.3

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Section: Discussionsupporting

confidence: 51%

Metabolic stability of superoxide adducts derived from newly developed cyclic nitrone spin traps

Bézière

Hardy

Poulhès

et al. 2014

Free Radical Biology and Medicine

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“…After 8 µs when the triplet benzophenone is relaxed, the absorption at 350 nm is still apparent and long-lived (with a lifetime of ca. 15±0.5 µs) and may correspond to bromine radical anion Br •− 2 (Ershov and Janata, 2003;Ershov et al, 2002;Grodkowski and Neta, 2002;Hurley et al, 1988;Zehavi and Rabani, 1972). This radical anion is known to absorb light from 300 to 400 nm with maximum absorption at 355 nm.…”

Section: Bromidementioning

confidence: 99%

Photoinduced oxidation of sea salt halides by aromatic ketones: a source of halogenated radicals

et al. 2009

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Abstract.The interactions between triplet state benzophenone and halide anion species (Cl − , Br − and I − ) have been studied by laser flash photolysis (at 355 nm) in aqueous solutions at room temperature. The decay of the triplet state of benzophenone was followed at 525 nm. Triplet lifetime measurements gave rate constants, k q (M −1 s −1 ), close to diffusion controlled limit for iodide (∼8×10 9 M −1 s −1 ), somewhat less for bromide (∼3×10 8 M −1 s −1 ) and much lower for chloride (<10 6 M −1 s −1 ). The halide (X − ) quenches the triplet state; the resulting product has a transient absorption at 355 nm and a lifetime much longer than that of the benzophenone triplet state, is formed. This transient absorption feature matches those of the corresponding radical anion (X − 2 ). We therefore suggest that such reactive quenching is a photosensitized source of halogen in the atmosphere or the driving force for the chemical oxidation of the oceanic surface micro layer.

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“…To investigate the reaction between HE and · OH radicals, e aq -was converted into · OH by saturating the solution with N 2 O (reaction 1, k 1 = 9.1 × 10 9 M -1 s -1 [14]): (1) For the reaction of HE with Br 2 ·-, pulse radiolysis was carried out in the presence of KBr (0.1 M), so that the bromide anions reacted with · OH to from Br 2 ·-via reactions 2 and 3 (k 2 = 1.1 × 10 10 M -1 s -1 , k 3 = 1.2 × 10 10 M -1 s -1 [16]):…”

Section: Pulse Radiolysismentioning

confidence: 99%

Pulse radiolysis and steady-state analyses of the reaction between hydroethidine and superoxide and other oxidants

Zielonka¹,

Sarna²,

Roberts³

et al. 2006

Archives of Biochemistry and Biophysics

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Hydroethidine (HE) is a cell-permeable probe used for the intracellular detection of superoxide. Here we report the direct measurement of the rate constant between hydroethidine and superoxide radical anion using the pulse radiolysis technique. This reaction rate constant was calculated to be ca. 2·10 6 M -1 s -1 in water:ethanol (1:1) mixture. The spectral characteristics of the intermediates indicated that the one-electron oxidation product of HE was different from the one-electron reduction product of ethidium (E + ). The HPLC-electrochemical measurements of incubation mixtures containing HE and the oxygenated Fenton's reagent (Fe 2+ /DTPA/H 2 O 2 ) in the presence of aliphatic alcohols or formate as a superoxide generating system revealed 2-OH-E + as a major product. Formation of 2-OH-E + by the Fenton's reagent without additives was shown to be superoxide dismutase-sensitive and we attribute the formation of superoxide radical anion to the one-electron reduction of oxygen by the DTPA-derived radical. Addition of tert-butanol, DMSO, and potassium bromide to the Fenton's system caused inhibition of 2-OH-E + formation. Results indicate that reducing and oxidizing radicals have differential effects on the formation of 2-OH-E + .

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Oxidation of aqueous bromide ions by hydroxyl radicals. Pulse radiolytic investigation

Cited by 249 publications

References 2 publications

Metabolic stability of superoxide adducts derived from newly developed cyclic nitrone spin traps

Metabolic stability of superoxide adducts derived from newly developed cyclic nitrone spin traps

Photoinduced oxidation of sea salt halides by aromatic ketones: a source of halogenated radicals

Pulse radiolysis and steady-state analyses of the reaction between hydroethidine and superoxide and other oxidants

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