scholarly journals The spin trapping of pyrimidine nucleotide free radicals in a Fenton system

1989 ◽  
Vol 261 (3) ◽  
pp. 831-839 ◽  
Author(s):  
W D Flitter ◽  
R P Mason
Keyword(s):  
Free Radicals ◽  
Hydroxyl Radical ◽  
Spin Trap ◽  
Gamma Ray ◽  
Thiobarbituric Acid ◽  
Spin Trapping ◽  
Pyrimidine Nucleotide ◽  
Gamma Ray Irradiation ◽  
Radical Attack ◽  
Fenton System

The reaction of the hydroxyl radical, generated by a Fenton system, with pyrimidine deoxyribonucleotides was investigated by using the e.s.r. technique of spin trapping. The spin trap t-nitrosobutane was employed to trap secondary radicals formed by the reaction of the hydroxyl radical with these nucleotides. The results presented here show that hydroxyl-radical attack on thymidine, 2-deoxycytidine 5-monophosphate and 2-deoxyuridine 5-monophosphate produced nucleotide-derived free radicals. The results indicate that .OH radical attack occurs predominantly at the carbon-carbon double bond of the pyrimidine base. The e.s.r. studies showed a good correlation with previous results obtained by authors who used x- or gamma-ray irradiation to generate the hydroxyl radical. A thiobarbituric acid assay was also used to monitor the damage produced to the nucleotides by the Fenton system. These results showed qualitative agreement with the spin-trapping studies.

Utilisation des pièges à radicaux en vue de mettre en évidence des intermédiaires dans la photolyse de complexes contenant une liaison CoIII—C

1982 ◽  
Vol 60 (12) ◽  
pp. 1402-1413 ◽  
Author(s):  
Philippe Maillard ◽  
Charles Giannotti
Keyword(s):  
Free Radicals ◽  
Hydrogen Atom ◽  
Spin Trap ◽  
Spin Trapping ◽  
Spin Adduct ◽  
Efficient Manner ◽  
Solvent Cage ◽  
Selective Deuteration ◽  
Equatorial Ligand ◽  
Spin Trapping Technique

Using the spin trapping technique with 5,5′-dimethyl 1-pyrroline N-oxide (DMPO), phenyl-N-tert-butyl nitrone (PBN), nitrosodurene (ND), and α-4-pyridyl 1-oxide N-tert-butl nitrone (4-POBN), or their mixtures, we have been able to detect two types of radicals, one is a hydrogen atom spin adduct and the other is the corresponding alkyl of the alkylcobaloximes, salens or cobalamines.By the use of selective deuteration and the preparation of the benzyl bis(diphenylglyoximato)-pyridinato cobaloxime, we have shown that the spin trapped hydrogen atom comes from the chelated hydrogen of the dimethylglyoximato anion of the equatorial ligand of CoIII complexes. Using a mixture of two spin traps gives rise to an esr spectrum containing, at the same time, the hydrogen atom and alkyl spin adducts.To explain such an efficient spin trapping reaction while the homolysis is in competition with a β-elimination process, it should be postulated that the photolysis of such compounds proceeds through a solvent cage environment. This hypothesis explains the strong influence of solvents on the nature of the free radicals trapped. Also the spin trap diffuses in the solvent cage, and is able to trap in a very efficient manner any free radicals occurring in the solvent cage. The excited CoIII complexes and the spin trap in the solvent cage behave like an exciplex, which could explain the spin trapping of the hydrogen atom.

scholarly journals Spin trapping studies of essential oils in lipid systems

Nukleonika ◽  
2015 ◽  
Vol 60 (3) ◽  
pp. 461-468 ◽  
Author(s):  
Katerina Makarova ◽  
Kinga Drązikowska ◽  
Beata Suska ◽  
Katarzyna Zawada ◽  
Iwona Wawer
Keyword(s):  
Essential Oils ◽  
Fenton Reaction ◽  
Spin Trap ◽  
Spin Trapping ◽  
Oh Radicals ◽  
Bath Salts ◽  
Radical Adduct ◽  
Hyperfine Splittings ◽  
Skin Care Products ◽  
Fenton System

Abstract In the present work, we report the results of a spin trapping ESR study of four essential oils widely used for skin care products such as creams and bath salts. The studied essential oils are Rosmarini aetheroleum (rosemary), Menthae piperitae aetheroleum (mint), Lavandulae aetheroleum (lavender), and Thymi aetheroleum (thyme). Fenton reaction in the presence of ethanol was used to generate free radicals. The N-tert-butyl-α-phenylnitrone (PBN) was used as a spin trap. In the Fenton reaction, the rosemary oil had the lowest effect on radical adduct formation as compared to the reference Fenton system. Since essential oils are known to be lipid soluble, we also conducted studies of essential oils in Fenton reaction in the presence of lipids. Two model lipids were used, namely 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC). The obtained results suggested that in the presence of DOPC lipids, the •OH and PBN/•CHCH3(OH) radicals are formed in both phases, that is, water and lipids, and all the studied essential oils affected the Fenton reaction in a similar way. Whereas, in the DPPC system, the additional type of PBN/X (aN = 16.1 G, aH = 2.9 G) radical adduct was generated. DFT calculations of hyperfine splittings were performed at B3LYP/6-311+G(d,p)/EPR-II level of theory for the set of c-centered PBN adducts in order to identify PBN/X radical.

scholarly journals The oxidation of oxyhaemoglobin by glyceraldehyde and other simple monosaccharides

1984 ◽  
Vol 217 (3) ◽  
pp. 615-622 ◽  
Author(s):  
P J Thornalley ◽  
S P Wolff ◽  
M J C Crabbe ◽  
A Stern
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Phosphate Buffer ◽  
Spin Trap ◽  
Spin Trapping ◽  
Free Radical Production ◽  
Radical Production ◽  
Hydroxyalkyl Radical ◽  
Aldehyde Derivative

Glyceraldehyde and other simple monosaccharides oxidize oxyhaemoglobin to methaemoglobin in phosphate buffer at pH 7.4 and 37 degrees C, with the concomitant production of H2O2 and an alpha-oxo aldehyde derivative of the monosaccharide. Simple monosaccharides also reduce methaemoglobin to ferrohaemichromes (non-intact haemoglobin) at pH 7.4 and 37 degrees C. Carbonmonoxyhaemoglobin is unreactive towards oxidation by autoxidizing glyceraldehyde. Free-radical production from autoxidizing monosaccharides with haemoglobins was observed by the e.s.r. technique of spin trapping with the spin trap 5,5-dimethyl-l-pyrroline N-oxide. Hydroxyl and l-hydroxyalkyl radical production observed from monosaccharide autoxidation was quenched in the presence of oxyhaemoglobin and methaemoglobin. The haemoglobins appear to quench the free radicals by reaction with the free radicals and/or the ene-diol precursor of the free radical.

Free Radicals from Purine Nucleosides after Hydroxyl Radical Attack

1976 ◽  
Vol 65 (2) ◽  
pp. 220 ◽  
Author(s):  
Jack Schmidt ◽  
Donald C. Borg
Keyword(s):  
Free Radicals ◽  
Hydroxyl Radical ◽  
Radical Attack

Synthesis and EPR Evaluation of the Nitrone PBN-[tert-13C] for Spin Trapping Competition

2002 ◽  
Vol 57 (1) ◽  
pp. 127-132 ◽  
Author(s):  
Yong-Kang Zhang ◽  
Kirk R. Maples
Keyword(s):  
Free Radicals ◽  
Hydroxyl Radical ◽  
Hyperfine Splitting ◽  
Internal Standard ◽  
Spin Trapping ◽  
Epr Spectrum ◽  
Competition Study ◽  
Epr Signal ◽  
Signal Overlap ◽  
Epr Spin Trapping

N-[tert-13C]Butyl C-phenyl nitrone (PBN-[tert-13C]) has been synthesized for an EPR spin trapping competition study. The newly synthesized PBN-[tert-13C] shows different 13C-hyperfine splitting constants (a13C) when it traps free radicals as compared to another 13C-labeled PBN analogue, N-tert-butyl C-phenyl [nitronyl-13C]nitrone (PBN-[nitronyl-13C]). The PBN- [tert-13C] hydroxyl adduct gives a larger a13C value (5.14 G) as compared to the PBN-[nitronyl-13C] hydroxyl adduct (4.36 G). This gain ofthe a13C value decreases the chance of EPR signal overlap, thus providing a more resolved EPR spectrum when PBN-[tert-13C] is used as an internal standard for EPR spin trapping competition studies of hydroxyl radical formation.

scholarly journals Insight into the nature and site of oxygen-centered free radical generation by endothelial cell monolayers using a novel spin trapping technique

Blood ◽  
1992 ◽  
Vol 79 (3) ◽  
pp. 699-707 ◽  
Author(s):  
BE Britigan ◽  
TL Roeder ◽  
DM Shasby
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Free Radical ◽  
Hydroxyl Radical ◽  
Spin Trap ◽  
Spin Trapping ◽  
Cathepsin G ◽  
Cell Monolayers ◽  
Radical Production ◽  
Radical Generation

Abstract Spin trapping, a sensitive and specific means of detecting free radicals, is optimally performed on cell suspensions. This makes it unsuitable for the study of adherent endothelial cell monolayers because disrupting the monolayer to induce a cell suspension could introduce confounding factors. This problem was eliminated through the use of endothelial cells that were grown to confluence on microcarrier beads. Using the spin trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), the nature of free radical species generated by suspensions of microcarrier bead adherent porcine pulmonary endothelial cells under various forms of oxidant stress was examined. Exposure of these endothelial cells to paraquat resulted in the spin trapping of superoxide (.O2-). Endothelial cell incubation in the presence of either bolus or continuous fluxes of hydrogen peroxide (H2O2) yielded spin trap evidence of hydroxyl radical formation, which was preventable by pretreating the cells with deferoxamine. Chromium oxalate which eliminates extracellular electron paramagnetic resonance spectrometry (EPR) signals, prevented the detection of DMPO spin adducts generated by paraquat but not H2O2-treated endothelial cells. When endothelial cells were coincubated with PMA-stimulated monocytes evidence of both .O2- and hydroxyl radical production was detected, whereas with PMA- stimulated neutrophils only .O2- production could be confirmed. Neutrophil elastase, cathepsin G, and the combination of PMA and A23187 have previously been suggested to induce endothelial cell oxy-radical generation. However, exposure of endothelial cells to each of these agents did not yield DMPO spin adducts or cyanide-insensitive endothelial cell O2 consumption. These data indicate that endothelial cell exposure: to paraquat induces extracellular .O2- formation; to H2O2 leads to intracellular hydroxyl radical production; and to elastase, cathepsin G, or A23187/PMA does not appear to cause oxy- radical generation.

scholarly journals Insight into the nature and site of oxygen-centered free radical generation by endothelial cell monolayers using a novel spin trapping technique

Blood ◽  
1992 ◽  
Vol 79 (3) ◽  
pp. 699-707
Author(s):  
BE Britigan ◽  
TL Roeder ◽  
DM Shasby
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Free Radical ◽  
Hydroxyl Radical ◽  
Spin Trap ◽  
Spin Trapping ◽  
Cathepsin G ◽  
Cell Monolayers ◽  
Radical Production ◽  
Radical Generation

Spin trapping, a sensitive and specific means of detecting free radicals, is optimally performed on cell suspensions. This makes it unsuitable for the study of adherent endothelial cell monolayers because disrupting the monolayer to induce a cell suspension could introduce confounding factors. This problem was eliminated through the use of endothelial cells that were grown to confluence on microcarrier beads. Using the spin trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), the nature of free radical species generated by suspensions of microcarrier bead adherent porcine pulmonary endothelial cells under various forms of oxidant stress was examined. Exposure of these endothelial cells to paraquat resulted in the spin trapping of superoxide (.O2-). Endothelial cell incubation in the presence of either bolus or continuous fluxes of hydrogen peroxide (H2O2) yielded spin trap evidence of hydroxyl radical formation, which was preventable by pretreating the cells with deferoxamine. Chromium oxalate which eliminates extracellular electron paramagnetic resonance spectrometry (EPR) signals, prevented the detection of DMPO spin adducts generated by paraquat but not H2O2-treated endothelial cells. When endothelial cells were coincubated with PMA-stimulated monocytes evidence of both .O2- and hydroxyl radical production was detected, whereas with PMA- stimulated neutrophils only .O2- production could be confirmed. Neutrophil elastase, cathepsin G, and the combination of PMA and A23187 have previously been suggested to induce endothelial cell oxy-radical generation. However, exposure of endothelial cells to each of these agents did not yield DMPO spin adducts or cyanide-insensitive endothelial cell O2 consumption. These data indicate that endothelial cell exposure: to paraquat induces extracellular .O2- formation; to H2O2 leads to intracellular hydroxyl radical production; and to elastase, cathepsin G, or A23187/PMA does not appear to cause oxy- radical generation.

Enhancement of hydroxyl radical generation by phenols and their reaction intermediates during ozonation

1998 ◽  
Vol 38 (6) ◽  
pp. 147-154 ◽  
Author(s):  
Hideo Utsumi ◽  
Sang-Kuk Han ◽  
Kazuhiro Ichikawa
Keyword(s):  
Hydroxyl Radical ◽  
Hydroxyl Radicals ◽  
Spin Trapping ◽  
Active Species ◽  
Generation Rate ◽  
Peak Height Ratio ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Phenol Derivatives ◽  
Semiquinone Radicals

Generation of hydroxyl radicals, one of the major active species in ozonation of water was directly observed with a spin-trapping/electron spin resonance (ESR) technique using 5,5-dimethyl-1-pyrrolineN-oxide (DMPO) as a spin-trapping reagent. Hydroxyl radical were trapped with DMPO as a stable radical, DMPO-OH. Eighty μM of ozone produced 1.08 X 10-6M of DMPO-OH, indicating that 1.4% of •OH is trapped with DMPO. Generation rate of DMPO-OH was determined by ESR/stopped-flow measurement. Phenol derivatives increased the amount and generation rate of DMPO-OH, indicating that phenol derivatives enhance •OH generation during ozonation of water. Ozonation of 2,3-, 2,5-, 2,6-dichlorophenol gave an ESR spectra of triplet lines whose peak height ratio were 1:2:1. ESR parameters of the triplet lines agreed with those of the corresponding dichloro-psemiquinone radical. Ozonation of 2,4,5- and 2,4,6-trichlorophenol gave the same spectra as those of 2,5- and 2,6-dichlorophenol, respectively, indicating that a chlorine group in p-position is substituted with a hydroxy group during ozonation. Amounts of the radical increased in an ozone-concentration dependent manner and were inhibited by addition of hydroxyl radical scavengers. These results suggest that p-semiquinone radicals are generated from the chlorophenols by hydroxyl radicals during ozonation. The p-semiquinone radicals were at least partly responsible for enhancements of DMPO-OH generation.

Water-rock reactions during gamma-ray irradiation

1996 ◽  
Vol 11 (3) ◽  
pp. 461-469 ◽  
Author(s):  
C YONEZAWA ◽  
T TANAKA ◽  
H KAMIOKA
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Irradiation
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