EPR detection of the unstable tert-butylperoxyl radical adduct of the spin trap 5,5-dimethyl-1-pyrroline N-oxide: a combined spin-trapping and continuous-flow investigation

2002 ◽  
pp. 2044-2051 ◽  
Author(s):  
Clare M. Jones ◽  
Mark J. Burkitt
Keyword(s):  
Continuous Flow ◽  
Spin Trap ◽  
Spin Trapping ◽  
Radical Adduct ◽  
Flow Investigation

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 Site-specific spin trapping of tyrosine radicals in the oxidation of metmyoglobin by hydrogen peroxide

1998 ◽  
Vol 330 (3) ◽  
pp. 1293-1299 ◽  
Author(s):  
R. Michael GUNTHER ◽  
Richard A. TSCHIRRET-GUTH ◽  
H. Ewa WITKOWSKA ◽  
C. Yang FANN ◽  
P. David BARR ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Spin Trap ◽  
Sperm Whale ◽  
Spin Trapping ◽  
Tryptophan Residue ◽  
Radical Adduct ◽  
Unpaired Electron Density ◽  
Trapping Agent ◽  
Tyrosine Radical ◽  
Radical Yield

The reaction between metmyoglobin and hydrogen peroxide produces both a ferryl-oxo heme and a globin-centred radical(s) from the two oxidizing equivalents of the hydrogen peroxide. Evidence has been presented for localization of the globin-centred radical on one tryptophan residue and tyrosines 103 and 151. When the spin-trapping agent 5,5-dimethyl-1-pyrroline N-oxide (DMPO) is included in the reaction mixture, a radical adduct has been detected, but the residue at which that adduct is formed has not been determined. Replacement of either tryptophans 7 and 14 or tyrosines 146 and 151 with phenylalanine has no effect on the formation of DMPO adduct in the reaction with hydrogen peroxide. When tyrosine 103 is replaced with phenylalanine, however, only DMPOX, a product of the oxidation of the spin-trap, is detected. Tyrosine-103 is, therefore, the site of radical adduct formation with DMPO. The spin trap 2-methyl-2-nitrosopropane (MNP), however, forms radical adducts with any recombinant sperm whale metmyoglobin that contains either tyrosine 103 or 151. Detailed spectral analysis of the DMPO and MNP radical adducts of isotopically substituted tyrosine radical yield complete structural determinations. The multiple sites of trapping support a model in which the unpaired electron density is spread over a number of residues in the population of metmyoglobin molecules, at least some of which are in equilibrium with each other.

scholarly journals Formation of peroxide- and globin-derived radicals from the reaction of methaemoglobin and metmyoglobin with t-butyl hydroperoxide: an ESR spin-trapping investigation

1997 ◽  
Vol 322 (2) ◽  
pp. 633-639 ◽  
Author(s):  
Jolanda Van der ZEE
Keyword(s):  
Spin Trap ◽  
Hydrogen Abstraction ◽  
Spin Trapping ◽  
Tyrosyl Radical ◽  
Alkoxyl Radical ◽  
Butyl Hydroperoxide ◽  
Heterolytic Cleavage ◽  
Esr Spin Trapping ◽  
Radical Adduct ◽  
Protein Radicals

The reaction of human methaemoglobin and horse metmyoglobin with t-butyl hydroperoxide (t-BuOOH) was investigated with the ESR spin-trapping technique. With the spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) the formation of peroxyl, alkoxyl and methyl radicals derived from t-BuOOH could be detected. The relative contributions of these radicals were determined at various DMPO concentrations by computer simulation. From these data it could be concluded that the alkoxyl radical was the initial radical produced, which indicates that the hydroperoxide is cleaved homolytically. Further investigations, with the nitroso spin trap 2-methyl-2-nitrosopropane (MNP), showed the formation of globin-centred radicals. Non-specific proteolysis of the MNP adducts revealed isotropic three-line spectra, which means that the radical adducts were centred on a tertiary carbon with no bonds to a hydrogen or nitrogen. Comparison with MNP adducts of several amino acids indicated that in methaemoglobin the radical adduct was most probably located on a valine residue. With metmyoglobin the same adduct was obtained, whereas an additional adduct could be assigned to a tyrosyl radical. These protein radicals most probably resulted from hydrogen abstraction by the metal–oxo species, formed by heterolytic cleavage of the hydroperoxide. These results therefore show that homolytic cleavage of the hydroperoxide leads to the formation of peroxide-derived radicals, whereas concurrent heterolytic cleavage results in protein-derived radicals.

scholarly journals Embedding cyclic nitrone in mesoporous silica particles for EPR spin trapping of superoxide and other radicals

The Analyst ◽  
2019 ◽  
Vol 144 (14) ◽  
pp. 4194-4203 ◽  
Author(s):  
Eric Besson ◽  
Stéphane Gastaldi ◽  
Emily Bloch ◽  
Jacek Zielonka ◽  
Monika Zielonka ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Radical Anion ◽  
Superoxide Radical ◽  
Spin Trap ◽  
Aqueous Media ◽  
Spin Trapping ◽  
Silica Particles ◽  
Superoxide Radical Anion ◽  
Wide Range ◽  
Epr Spin Trapping

Mesoporous silica functionalised with a cyclic spin trap enabled the identification of a wide range of radicals in organic and aqueous media, including superoxide radical anion.

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.

scholarly journals Mechanism in the reaction of cytochrome c oxidase with organic hydroperoxides: an ESR spin-trapping investigation

2002 ◽  
Vol 365 (2) ◽  
pp. 461-469 ◽  
Author(s):  
Yeong-Renn CHEN ◽  
Ronald P. MASON
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Spin Trap ◽  
Spin Trapping ◽  
Initial Reaction ◽  
Radical Species ◽  
Alkoxyl Radical ◽  
Tyrosine Residues ◽  
Esr Spin Trapping ◽  
Organic Hydroperoxides

Organic hydroperoxides are of great utility in probing the reaction mechanism and the toxicological consequences of lipid peroxidation. In the present study, ESR spin-trapping was employed to investigate the peroxidation of mitochondrial cytochrome c oxidase (CcO) with t-butyl hydroperoxide (t-BuOOH) and cumene hydroperoxide (CumOOH). The spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) was used to detect the radical species formed from the reaction of CcO with t-BuOOH. The presence of t-BuOOH-derived alkoxyl radical (t-BuO˙) as the primary radical indicates reductive scission of the O—O bond by CcO. The ESR signal of DMPO/˙Ot-Bu can be partially abolished by cyanide, implying that the reductive cleavage involved the haem a3CuB binuclear site of CcO. A nitroso spin trap, 2-methyl-2-nitrosopropane (MNP), was used to detect and identify radical species from the reaction of CcO with CumOOH. In addition to the t-BuOOH-derived methyl, hydroxylmethyl and tertiary carbon-centred radicals, a protein-derived radical was detected. The intensity of the ESR signal from the protein radical increased with the CumOOH concentration at low CumOOH/CcO ratios, with maximal intensity at a ratio of 100mol of CumOOH/mol of CcO. The immobilized protein radical adduct of MNP was stable and persistent after dialysis; it was also resistant to proteolytic digestion, suggesting that it was formed in the transmembrane region, a region that is not accessible to proteases. Its signal was greatly enhanced when CcO cysteine residues were chemically modified by N-ethylmaleimide, when the tryptophan residues in CcO were oxidized by N-bromosuccimide, and when tyrosine residues on the surface of CcO were iodinated, showing that a radical equilibrium was established among the cysteine, tryptophan and tyrosine residues of the protein-centred radical. Pre-treatment of CcO with cyanide prevented detectable MNP adduct formation, confirming that the haem a3-CuB binuclear centre was the initial reaction site. When the CcO was pre-treated with 10mM (100 equivalents) of CumOOH, the enzyme activity decreased by more than 20%. This inhibition was persistent after dialysis, suggesting that the detected protein-centred radical was, in part, involved in the irreversible inactivation by CumOOH. Visible spectroscopic analysis revealed that the haem a of CcO was not affected during the reaction. However, the addition of pyridine to the reaction mixture under alkaline conditions resulted in the destruction of the haem centre of CcO, suggesting that its protein matrix rather than its haem a is the target of oxidative damage by the organic hydroperoxide.

Spin trapping chemistry of 3,3,5,5-tetramethylpyrroline-N-oxide: an improved cyclic spin trap

1981 ◽  
Vol 59 (4) ◽  
pp. 756-758 ◽  
Author(s):  
Edward G. Janzen ◽  
Raghav V. Shetty ◽  
Susan M. Kunanec
Keyword(s):  
Spin Trap ◽  
Esr Spectra ◽  
Spin Trapping

The use of 3,3,5,5-tetramethylpyrroline-N-oxide as a spin trap has been investigated. Spin adducts are found to be more persistent than for 5,5-dimethylpyrroline-N-oxide (DMPO) although the esr spectra are quite similar.

Electron spin resonance studies of the reactions of sorbate with nitrite in the presence of a spin trap

1982 ◽  
Vol 60 (12) ◽  
pp. 1598-1601 ◽  
Author(s):  
Avinash Joshi ◽  
Dennis M Hinton ◽  
George C Yang
Keyword(s):  
Electron Spin Resonance ◽  
Double Bond ◽  
Sodium Nitrite ◽  
Spin Trap ◽  
Spin Trapping ◽  
Potassium Sorbate ◽  
Radical Product ◽  
Rapid Decomposition ◽  
Esr Spectrum ◽  
Spin Resonance

An esr spectrum was generated when a spin trap, t-nitroso butane (tNB), was added to potassium sorbate solution at pH of 6.4. This spectrum can be explained by the abstraction of allylic hydrogen by NO2, generated by the decomposition of tNB, followed by spin trapping of the radical product. With increasing concentration of NO2, which was accomplished by either the addition of sodium nitrite or by lowering the pH to cause rapid decomposition of tNB, a different esr spectrum was observed. This spectrum can be accounted for by a radical formed by addition of NO2 to the 4,5 double bond of the sorbate and subsequent trapping by tNB.

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