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Spin Trap (spin + trap)

Distribution by Scientific Domains

Life Sciences	40%
Chemistry	30%

Selected Abstracts

Laser Induced Marking of Polymer Chains with Radical Spin Traps

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 6 2008
Thomas Junkers
Abstract A pathway for marking of polymer chains with radical spin traps during pulsed laser polymerization in free radical polymerization is presented. By introducing a so-called marker that forms a non-propagating radical at (or shortly after) the incidence of a laser pulse, a polymer subdistribution is generated by specifically terminating propagating radicals via combination with such a marker radical. The generated polymer subdistribution can subsequently be imaged by modern soft-ionization mass spectrometry. Herein, the general methodology of the method in which such marker is generated via reaction of an initiating radical with a nitrone is demonstrated on the examples of BA and VAc. [source]

Sumatriptan Scavenges Superoxide, Hydroxyl, and Nitric Oxide Radicals: In Vitro Electron Spin Resonance Study

HEADACHE, Issue 9 2002
DMSc, Yukio Ikeda MD
Background.,The molecular mechanisms of migraine have not yet been clarified. Oxygen free radicals have been implicated in the genesis of many pathological processes, including migraine. Sumatriptan succinate is known to be a very effective drug for acute relief of migraine attack. Objective.,To investigate the direct scavenging activities of sumatriptan for superoxide, hydroxyl, and nitric oxide (NO) radicals using electron spin resonance (ESR) spectroscopy. Methods.,Measurement of superoxide and hydroxyl radical scavenging activities was performed by ESR using 5,5-dimethyl-1-pyrroline- N -oxide as a spin trap. NO was generated from 1-hydroxy-2-oxo-3-(N -3-methyl-3-aminopropyl)-3-methyl-1-triazene and analyzed by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl produced from the reaction between 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide and NO. Results.,The ESR study demonstrated that sumatriptan scavenged superoxide, hydroxyl, and NO in a dose-dependent manner. Conclusion.,Sumatriptan has direct scavenging activity on free radicals and NO. Acute migraine drugs with antioxidant properties may provide heretofore unheralded benefits via this mechanism. [source]

Oxidative Stress Following Traumatic Brain Injury in Rats

JOURNAL OF NEUROCHEMISTRY, Issue 5 2000
Detection of Free Radical Intermediates, Quantitation of Biomarkers
Abstract: Oxidative stress may contribute to many pathophysiologic changes that occur after traumatic brain injury. In the current study, contemporary methods of detecting oxidative stress were used in a rodent model of traumatic brain injury. The level of the stable product derived from peroxidation of arachidonyl residues in phospholipids, 8- epi -prostaglandin F2,, was increased at 6 and 24 h after traumatic brain injury. Furthermore, relative amounts of fluorescent end products of lipid peroxidation in brain extracts were increased at 6 and 24 h after trauma compared with sham-operated controls. The total antioxidant reserves of brain homogenates and water-soluble antioxidant reserves as well as tissue concentrations of ascorbate, GSH, and protein sulfhydryls were reduced after traumatic brain injury. A selective inhibitor of cyclooxygenase-2, SC 58125, prevented depletion of ascorbate and thiols, the two major water-soluble antioxidants in traumatized brain. Electron paramagnetic resonance (EPR) spectroscopy of rat cortex homogenates failed to detect any radical adducts with a spin trap, 5,5-dimethyl-1-pyrroline N -oxide, but did detect ascorbate radical signals. The ascorbate radical EPR signals increased in brain homogenates derived from traumatized brain samples compared with sham-operated controls. These results along with detailed model experiments in vitro indicate that ascorbate is a major antioxidant in brain and that the EPR assay of ascorbate radicals may be used to monitor production of free radicals in brain tissue after traumatic brain injury. [source]

Effect of Exogenous and Endogenous Antioxidants on 3-Nitropionic Acid-Inducedin vivo Oxidative Stress and Striatal Lesions

JOURNAL OF NEUROCHEMISTRY, Issue 4 2000
Insights into Huntington's Disease
Abstract: 3-Nitropropionic acid (3-NP) is an irreversible inhibitor of complex II in the mitochondria. 3-NP toxicity has gained acceptance as an animal model of Huntington's disease (HD). In the present study, we confirmed that rats injected with 3-NP (20 mg/kg, i.p., daily for 4 days) exhibit increased oxidative stress in both striatum and cortical synaptosomes as well as lesions in the striatum. Synaptosomal membrane proteins from rats injected with 3-NP exhibited a decrease in W/S ratio, the relevant electron paramagnetic resonance (EPR) parameter used to determine levels of protein oxidation, and western blot analysis for protein carbonyls revealed direct evidence of increased synaptosomal protein oxidation. Treatment of rats with the brain-accessible free radical spin trap 5-diethoxyphosphoryl-5-methyl-1-pyrroline N -oxide (DEPMPO; 30 mg/kg, i.p., daily 2 h before 3-NP injection) or with N -acetylcysteine (NAC; 100 mg/kg, i.p., daily 2 h before 3-NP injection), a known glutathione precursor, before 3-NP treatments protects against oxidative damage induced by 3-NP as measured by EPR and western blot analysis for protein carbonyls. Furthermore, both DEMPMPO and NAC treatments before 3-NP administration significantly reduce striatal lesion volumes. These data suggest oxidative damage is a prerequisite for striatal lesion formation and that antioxidant treatment may be a useful therapeutic strategy against 3-NP neurotoxicity and perhaps against HD as well. [source]

trans -Resveratrol Protects Embryonic Mesencephalic Cells from tert -Butyl Hydroperoxide

JOURNAL OF NEUROCHEMISTRY, Issue 1 2000
Electron Param
Abstract : In recent years, the antioxidant and other pharmacological properties of resveratrol, a natural product present in grapes and wine, have attracted considerable interest from the biomedical research community. In an examination of the potential neuroprotective properties of the compound, we have investigated the ability of resveratrol to protect rat embryonic mesencephalic tissue, rich in dopaminergic neurones, from the prooxidant tert -butyl hydroperoxide. Using the electron paramagnetic resonance (EPR) spin-trapping technique, the main radicals detected in cell suspensions were the tert -butoxyl radical and the methyl radical, indicating the one-electron reduction of the peroxide followed by a ,-scission reaction. The appearance of EPR signals from the trapped radicals preceded the onset of cytotoxicity, which was almost exclusively necrotic in nature. The inclusion of resveratrol in incubations resulted in the marked protection of cells from tert -butyl hydroperoxide. In parallel spin-trapping experiments, we were able to demonstrate the scavenging of radicals by resveratrol, which involved direct competition between resveratrol and the spin trap for reaction with the radicals. To our knowledge, this is the first example in which cytoprotection by resveratrol has been demonstrated by EPR spin-trapping competition kinetics to be due to its scavenging of the radicals responsible for the toxicity of a prooxidant. [source]

Oxidative effects in uninfected tissue in leaves of French bean (Phaseolus vulgaris) containing soft rots caused by Botrytis cinerea

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 6 2003
Ingo Muckenschnabel
Abstract Several markers of oxidative processes have been measured in leaves of Phaseolus vulgaris infected with Botrytis cinerea, with the specific objective of investigating changes induced by this necrotrophic pathogen in tissue remote from the lesion. There was a progressive decrease with time in the contents of ascorbic acid (AA) in apparently healthy tissues from infected plants and non-inoculated plants grown under identical high-humidity conditions (abiotically stressed controls), and for periods >48 h this decrease was greater in the infected plants. This decline in AA content was accompanied by an elevation in the intensity of the electron paramagnetic resonance (EPR) signal from adducts of the spin trap ,-(4-pyridyl-1-oxide)- N - t -butylnitrone (POBN), a destabilisation of the (monodehydro) ascorbate radical (Asc·) signal in the presence of POBN, and an increase in the ratio of Asc· to AA in samples studied in the absence of the spin trap. These results are consistent with a shift in redox status to more oxidising conditions in apparently healthy tissue of infected plants and indicate the prevalence of chemical processes that are distinctly different from those in uninfected plants. However, no differences in lipid peroxidation products or the single-peak free radical and Fe(III) (g = 4.27) EPR signals were observed between these tissues distant from the lesions and those from abiotically stressed controls. In addition, the pathogen-derived sesquiterpene toxin botrydial and a second Mn(II) EPR signal, both of which are associated with Botrytis infection, were not detected in these ,apparently healthy' tissues. Copyright © 2003 Society of Chemical Industry [source]

Spatial Distribution of Protein Damage by Singlet Oxygen in Keratinocytes

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2008
Yu-Ying He
Singlet oxygen may be generated in cells by either endogenous or exogenous photosensitizers as a result of exposure to UV or visible irradiation. We have used immuno-spin trapping (Free Radic. Biol. Med. 36: 1214, 2004) to identify the subcellular targets of singlet oxygen generated by rose bengal (RB). Confocal fluorescence microscopy of HaCaT keratinocytes incubated with RB clearly showed that the dye entered the cells and was located mainly in the perinuclear region, probably associated with the Golgi apparatus and endoplasmic reticulum. Previous studies by Wright et al. (Free Radic. Biol. Med.34: 637, 2003) have shown that long-lived protein hydroperoxides (POOH) are present in cells exposed to singlet oxygen-generating dyes. The addition of reducing metal ions such as Cu+ to POOH results in the generation of protein-derived radicals, POO, and PO,, which react with the spin trap 5,5-dimethyl-1-pyrroline N -oxide (DMPO) to give relatively stable spin adducts. In order to determine the subcellular localization of the protein-DMPO adducts, we exposed keratinocytes to RB/light exposure and then incubated the cells with Cu+ and DMPO. After staining with antibody against DMPO followed by a secondary Alexa Fluor 488 goat anti-rabbit IgG, the intracellular distribution of protein-DMPO adducts was determined by confocal microscopy. The subcellular localization of the protein DMPO adducts was coincident with that of RB. This approach may provide information on the spatial distribution of singlet oxygen generated in cells. [source]

Improving the Trapping of Superoxide Radical with a ,-Cyclodextrin, 5-Diethoxyphosphoryl-5-methyl-1-pyrroline- N -oxide (DEPMPO) Conjugate

CHEMISTRY - A EUROPEAN JOURNAL, Issue 42 2009
Micaël Hardy Dr.
Trapped spin trap: CD-DEPMPO, a cyclodextrin,DEPMPO conjugate spin trap, exhibits improved performances in superoxide detection. Using blood as a biological model system, the superoxide CD-DEPMPO adduct was still unambiguously detected after 70 min, whereas using DEPMPO the signal of the superoxide adduct was not detected. (DEPMPO=5-diethoxyphosphoryl-5-methyl-1-pyrroline- N -oxide.) [source]

Photohydroxylation of 1,4-Benzoquinone in Aqueous Solution Revisited

CHEMISTRY - A EUROPEAN JOURNAL, Issue 2 2004
Justus von Sonntag Dr.
Abstract In water, photolysis of 1,4-benzoquinone, Q gives rise to equal amounts of 2-hydroxy-1,4-benzoquinone HOQ and hydroquinone QH2 which are formed with a quantum yield of ,=0.42, independent of pH and Q concentration. By contrast, the rate of decay of the triplet (,max=282 and ,410 nm) which is the precursor of these products increases nonlinearly (k=(2,3.8)×106 s,1) with increasing Q concentration ((0.2,10) mM). The free-radical yield detected by laser flash photolysis after the decay of the triplet also increases with increasing Q concentration but follows a different functional form. These observations are explained by a rapid equilibrium of a monomeric triplet Q* and an exciplex Q2* (K=5500±1000,M,1). While Q* adds water and subsequent enolizes into 1,2,4-trihydroxybenzene Ph(OH)3, Q2* decays by electron transfer and water addition yielding benzosemiquinone .QH and . OH adduct radicals .QOH. The latter enolizes to the 2-hydroxy-1,4-semiquinone radical .Q(OH)H within the time scale of the triplet decay and is subsequently rapidly (microsecond time scale) oxidized by Q to HOQ with the concomitant formation of .QH. On the post-millisecond time scale, that is, when .QH has decayed, Ph(OH)3 is oxidized by Q yielding HOQ and QH2 as followed by laser flash photolysis with diode array detection. The rate of this pH- and Q concentration-dependent reaction was independently determined by stopped-flow. This shows that there are two pathways to photohydroxylation; a free-radical pathway at high and a non-radical one at low Q concentration. In agreement with this, the yield of Ph(OH)3 is most pronounced at low Q concentration. In the presence of phosphate buffer, Q* reacts with H2PO4, giving rise to an adduct which is subsequently oxidized by Q to 2-phosphato-1,4-benzoquinone QP. The current view that . OH is an intermediate in the photohydroxylation of Q has been overturned. This view had been based on the observation of the . OH adduct of DMPO when Q is photolyzed in the presence of this spin trap. It is now shown that Q*/Q2* oxidizes DMPO (k ,1×108,M,1,s,1) to its radical cation which subsequently reacts with water. Q*/Q2* react with alcohols by H abstraction (rates in units of M,1,s,1): methanol (4.2×107), ethanol (6.7×107), 2-propanol (13×107) and tertiary butyl alcohol (,0.2×107). DMSO (2.7×109) and O2 (,2×109) act as physical quenchers. [source]