ESR study of the interaction of mononuclear and binuclear metal carbonyls with silicon hydrides and the use of these systems to generate ?-chlorine-containing radicals

Gasanov, R. G.; Freĭdlina, R. Kh.

doi:10.1007/bf00950276

Cited by 6 publications

(7 citation statements)

References 5 publications

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“…When the four M-Subs are irradiated in the presence of PBN, no PBN adduct is observed. Upon the addition of TTMSS, the tris(trimethylsilyl)silyl radical is easily detected (e.g., Figure ); i.e., the hyperfine coupling constants of the PBN adduct ( a N = 15.3; a H = 5.4 G) are in agreement with the already known values. , The new proposed M-Sub /TTMSS systems should be very attractive for both FRP and FRPCP as the silyl radical formed in efficiently adds to acrylates (2.2 × 10 7 M −1 s −1 to methyl acrylate) and is easily oxidized by iodonium salts (2.6 × 10 6 M −1 s −1 ). ,,, boldM- boldSub + normalR 1 normalR 2 normalR 3 Si− normalH → → normalR 1 normalR 2 normalR 3 Si • 1em false( normalh normalν false) …”

Section: Resultssupporting

confidence: 74%

“…The variation of the pseudo first order rate constants with the quencher concentration (Figure B) allows to determine the radical/quencher interaction bimolecular rate constants gathered in Table . These radicals do not exhibit a high addition rate constant to MA or EPOX but efficiently reacts with oxygen (rate constants close to the diffusion limit ∼3 × 10 9 M −1 s −1 ) and present a relatively low interaction with TTMSS (hydrogen abstraction rate constants <2 × 10 5 M −1 s −1 as in other metal centered radical/silane interactions , ). The oxidation of these investigated metal radicals by Ph 2 I + is also quite hard (Table ). Cp 2 Mo 2 false( CO false) 6 → CpMo • false( CO false) 3 + CpMo • false( CO false) 3 Cp 2 Ru 2 false( CO false) 4 → CpRu • false( CO false) 2 + CpRu • false( CO false) 2 CpMo • false( CO false) 3 + normalR 1 normalR 2 normalR 3 Si − normalH → CpMo ...…”

Section: Resultsmentioning

confidence: 98%

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On the Favorable Interaction of Metal Centered Radicals with Hydroperoxides for an Enhancement of the Photopolymerization Efficiency Under Air

Lalevée

Tehfe

Gigmès³

et al. 2010

Macromolecules

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International audienceFour metal-based photoinitiating systems (benzene?tricarbonylchromium(0), ArCr(CO)3, cyclopentadienylmolybdenum tricarbonyl dimer, Cp2Mo2(CO)6, diiron nonacarbonyl, Fe2(CO)9, and bis(cyclopentadienylruthenium dicarbonyl), Cp2Ru2(CO)4) are investigated by laser flash photolysis (LFP) and ESR?spin trapping (ESR?ST) experiments and checked as photoinitiators for both free radical promoted cationic photopolymerization (FRPCP) and free radical photopolymerization (FRP). New combinations with silanes instead of alkyl halides improve both the polymerization rates and the final conversions upon irradiation with UV/visible or visible light and laser diodes (405, 457, 473, and 532 nm) under air. The enhancement of the photopolymerization reaction under air in the presence of the selected compounds is ascribed to the reuse of the inherently present hydroperoxides through a set of reactions leading to additional initiating species. These systems are particularly attractive for FRPCP with excellent polymerization rates and final conversions

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Section: Resultssupporting

confidence: 74%

Section: Resultsmentioning

confidence: 98%

On the Favorable Interaction of Metal Centered Radicals with Hydroperoxides for an Enhancement of the Photopolymerization Efficiency Under Air

Lalevée

Tehfe

Gigmès³

et al. 2010

Macromolecules

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“…The phenyl structure of the MNP adduct is unambiguous (33)(34)(35)(36). Previously, an almost identical spectrum was found with sulfanilamide after UV photolysis (34).…”

Section: Discussionsupporting

confidence: 54%

Aminoglutethimide-Induced Protein Free Radical Formation on Myeloperoxidase: A Potential Mechanism of Agranulocytosis

Siraki

Jiang

Ehrenshaft

et al. 2007

Chem. Res. Toxicol.

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Aminoglutethimide (AG) is a first-generation aromatase inhibitor used for estrogen-dependent breast cancer. Unfortunately, its use has also been associated with agranulocytosis. We have investigated the metabolism of AG by myeloperoxidase (MPO) and the formation of an MPO protein free radical. We hypothesized that AG oxidation by MPO/H 2 O 2 would produce an AG cation radical that, in the absence of a biochemical reductant, would lead to the oxidation of MPO. We utilized a novel anti-DMPO antibody to detect DMPO (5,5-dimethyl-1-pyrroline N-oxide) covalently bound to protein, which forms only by the reaction of DMPO with a protein free radical. We found that AG metabolism by MPO/H 2 O 2 induced the formation of DMPO-MPO, which was inhibited by MPO inhibitors and ascorbate. Glutethimide, a congener of AG that lacks the aromatic amine, did not cause DMPO-MPO formation, indicating the necessity of oxidation of the aniline moiety in AG. When analyzed by electron spin resonance spectroscopy, we detected a phenyl radical adduct, derived from AG, which may be involved in the free radical formation on MPO. Furthermore, we also found protein-DMPO adducts in MPO-containing, intact human promyelocytic leukemia cells (HL-60). MPO was affinity-purified from HL-60 cells treated with AG/H 2 O 2 and was found to contain DMPO. These findings were also supported by the detection of protein free radicals with electron spin resonance in the cellular cytosolic lysate. The formation of an MPO protein free radical is believed to be mediated by one of two free radical drug metabolites of AG, one of which was characterized by spin trapping with 2-methyl-2-nitrosopropane. These results are the first demonstration of MPO freeradical detection by the anti-DMPO antibody that results from drug oxidation. We propose that drugdependent free radical formation on MPO may play a role in the origin of agranulocytosis.

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“…In this study, we have shown the peroxidase metabolism of PA to a substituted-phenyl radical demonstrated by ESR using spin trapping. The phenyl structure of the MNP adduct is unambiguous – . Previously, an almost identical spectrum was found with sulfanilamide after UV photolysis .…”

Section: Discussionmentioning

confidence: 61%

“…This species represents the radical adduct formed by the PA-derived phenyl radical metabolite reacting with MNP as proposed in Scheme 2. A large class of t-butyl-paraphenyl nitroxide radicals, which have been detected in water, have two equivalent hyperfine couplings of about 2 G arising from two ortho hydrogens and two equivalent hyperfine coupling constants of about 1 G arising from the two meta hydrogens (32)(33)(34)(35). The structure of this phenyl radical metabolite is unambiguous.…”

Section: Mpo Compound II Accumulation Occurs In the Presence Of Pa/h mentioning

confidence: 95%

Procainamide, but notN-Acetylprocainamide, Induces Protein Free Radical Formation on Myeloperoxidase: A Potential Mechanism of Agranulocytosis

Siraki

Deterding

Jiang

et al. 2008

Chem. Res. Toxicol.

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Procainamide (PA) is a drug that is used to treat tachycardia in post-operative patients or for long term maintenance of cardiac arrythmias. Unfortunately, its use has also been associated with agranulocytosis. Here we have investigated the metabolism of PA by myeloperoxidase (MPO) and the formation of an MPO protein free radical. We hypothesized that PA oxidation by MPO/H 2 O 2 would produce a PA cation radical that, in the absence of a biochemical reductant, would lead to the free-radical oxidation of MPO. We utilized a novel anti-DMPO antibody to detect DMPO (5,5-dimethyl-1-pyrroline N-oxide) covalently bound to protein, which forms only by the reaction of DMPO with a protein free radical. We found that PA metabolism by MPO/H 2 O 2 induced the formation of DMPO-MPO, which was inhibited by MPO inhibitors and ascorbate. N-acetyl-PA did not cause DMPO-MPO formation, indicating that the unsubstituted aromatic amine was more oxidizable. PA had a lower calculated ionization potential than N-acetyl-PA. The DMPO adducts of §To whom correspondence should be addressed: Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences, 111 TW Alexander Dr., Research Triangle Park, NC USA, 27709. T: (919) 541-5197, F: (919) 541-1043, sirakia@niehs.nih.gov.. Abbreviations: PA, procainamide; NAPA, N-acetyl-procainamide; MPO, myeloperoxidase; ESR, electron spin resonance; DTPA, diethylenetriaminepentaacetic acid; MNP, 2-methyl-2-nitrosopropane; DMPO, 5,5-dimethyl-1-pyrroline N-oxide; ABAH, 4-aminobenzoic acid hydrazide; G/GO,Glucose / glucose oxidase. MPO metabolism, as analyzed by electron spin resonance spectroscopy, included a nitrogen-centered radical and a phenyl radical derived from PA, either of which may be involved in the free radical formation on MPO. Furthermore, we also found protein-DMPO adducts in MPO-containing, intact human promyelocytic leukemia cells . MPO was affinity-purified from HL-60 cells treated with PA/H 2 O 2 and was found to contain DMPO using the anti-DMPO antibody. Mass spectrometry analysis confirmed the identity of the protein as human MPO. These findings were also supported by the detection of protein free radicals with electron spin resonance in the cellular cytosolic lysate. The formation of an MPO protein free radical is believed to be mediated by free radical metabolites of PA, which we characterized by spin trapping. We propose that drug-induced free radical formation on MPO may play a role in the origin of agranulocytosis. NIH Public AccessProcainamide (PA) is a sodium channel blocker which stabilizes electrical conduction in the heart. It is used for treating atrial tachycardia and is specifically recommended for atrial fibrillation of the Wolff-Parkinson-White syndrome (1). Unfortunately, agranulocytosis, an idiosyncratic adverse drug reaction, is associated with the use of procainamide (PA). This condition is characterized by severe neutropenia, where the absolute neutrophil count decreases below 500/uL (2,3), which greatly increases the risk of b...

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ESR study of the interaction of mononuclear and binuclear metal carbonyls with silicon hydrides and the use of these systems to generate ?-chlorine-containing radicals

Cited by 6 publications

References 5 publications

On the Favorable Interaction of Metal Centered Radicals with Hydroperoxides for an Enhancement of the Photopolymerization Efficiency Under Air

On the Favorable Interaction of Metal Centered Radicals with Hydroperoxides for an Enhancement of the Photopolymerization Efficiency Under Air

Aminoglutethimide-Induced Protein Free Radical Formation on Myeloperoxidase: A Potential Mechanism of Agranulocytosis

Procainamide, but notN-Acetylprocainamide, Induces Protein Free Radical Formation on Myeloperoxidase: A Potential Mechanism of Agranulocytosis

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