31P Labeled Cyclic Nitrones: A New Class of Spin Traps for Free Radicals in Biological Milieu

Barbati, Stéphane; Clément, Jean Louis; Olive, Gilles; Roubaud, Valérie; Tuccio, Béatrice; Tordo, Paul

doi:10.1007/978-94-017-1607-9_3

Cited by 31 publications

(34 citation statements)

References 29 publications

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“…The following compounds were prepared according to published procedures: diethyl(2-methylpyrrolidin-2-yl)phosphonate 1 (DEPMPH) 1 (17,18), diethyl(2-phenylpyrrolidin-2-yl)phosphonate 2 (19), tetraethyl(pyrrolidin-2,2-diyl)bisphosphonate 3, tetraisopropyl(pyrrolidin-2,2-diyl)bisphosphonate 4, and trans-tetraethyl (2,5- (20). The synthesis of cis-tetraethyl(2,5-dimethylpyrrolidin-2,5-diyl)bisphosphonate 5b will be described elsewhere.…”

Section: ␣-Phosphorylated Pyrrolidines (Structure 1a)mentioning

confidence: 99%

α- and β-Phosphorylated Amines and Pyrrolidines, a New Class of Low Toxic Highly Sensitive 31P NMR pH Indicators

Pietri¹,

Miollan²,

Martel³

et al. 2000

Journal of Biological Chemistry

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Fourteen linear and cyclic ␣-and ␤-aminophosphonates in which the P-atom is substituted by alkoxy groups have been synthesized and evaluated as 31 P NMR pH markers in Krebs-Henseleit buffer. pK a values varied with substitution in the range 1.3-9.1, giving potentially access to a wide range of pH. Temperature had a weak influence on pH and a dramatic increase in ionic strength slightly modified the pK a of the pyrrolidine diethyl(2-methylpyrrolidin-2-yl)phosphonate (DEPMPH). All compounds displayed a 4-fold better NMR sensitivity than inorganic phosphate or other commonly used phosphonates, as assessed by differences ␦ b -␦ a between the chemical shifts of the protonated and the unprotonated forms. In isolated perfused rat hearts, a non-toxic concentration window of 1.5-15 mM was determined for three representative compounds. Using empirical linear relationships, the experimental values of pK a , ␦ a , and ␦ b have been correlated with the two-dimensional structure, i.e. the chemical nature of substituents bonded to the secondary amine and P-atom. The data suggest that DEPMPH and its cyclic and linear variants are ideal versatile 31 P NMR probes for the study of tenuous pH changes in biological processes.Since the pioneering studies of Moon and Richards (1), 31 P NMR has become the standard noninvasive technique to determine the intracellular pH in a variety of biological models, based on the dependence of the endogenous inorganic phosphate (P i ) chemical shift on pH. In addition, the ex vivo or in vivo use of 31 P NMR can concomitantly give access to dynamic processes involving the cellular phosphorylated metabolites. However, the usefulness of P i as a 31 P NMR probe for the measurement of pH in biological systems is limited by its low and varying concentration during metabolism and by its sensitivity to ionic strength. Indeed, owing to the large line widths of cellular peaks, and since the mean difference ⌬␦ ab between the 31 P NMR chemical shifts of the protonated (␦ a ) and the unprotonated (␦ b ) forms of P i is only 2.6 -2.7 ppm, it cannot be used to provide information on differences on pH between intra-and extracellular compartments of less than 0.2 pH units (2).A number of endogenous and exogenous analogues of phosphates and phosphonic acid metabolites have been tested as alternatives to P i for the 31 P NMR measurement of pH but their pK a and chemical shifts were found to be influenced by ionic strength and Mg 2ϩ concentration while their NMR sensitivity ⌬␦ ab was not greatly increased with respect to that of P i (1-4). Later, it was considered that changing the chemical nature of the substituents around the protonation site of selected phosphates (i.e. the two anionic oxygens) might result in an increase in the NMR sensitivity for pH determinations. Therefore, commercially available alkyl-and aminophosphonates have been extensively studied in test solutions (3-11), cell cultures or preparations (5-9, 12), tumors (10), and isolated organs (13-16). The most commonly used charged phosphonates (e.g. me...

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Section: ␣-Phosphorylated Pyrrolidines (Structure 1a)mentioning

confidence: 99%

α- and β-Phosphorylated Amines and Pyrrolidines, a New Class of Low Toxic Highly Sensitive 31P NMR pH Indicators

Pietri¹,

Miollan²,

Martel³

et al. 2000

Journal of Biological Chemistry

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“…We previously reported the synthesis and spin trapping properties of a new nitrone, the 2-diethoxyphosphoryl-2-methyl-3,4-dihydro-2H-pyrrole-1-oxide (DEPMPO) 2 [5]. DEPMPO can be easily prepared by a two step-synthesis [6] and it was shown to trap efficiently oxygen-centered radicals. In phosphate buffer at pH7.0, the persistence of the DEPMPO/O 2 -• superoxide adduct is approximately 15 times higher than that of DMPO/O 2 -• and the consecutive formation of DEPMPO/HO • was not observed.…”

Section: Introductionmentioning

confidence: 99%

2-ethoxycarbonyl-2-methyl-3,4-dihydro-2H-pyrrole-1-oxide: evaluation of the spin trapping properties

Olive¹,

Mercier²,

Moigne³

et al. 2000

Free Radical Biology and Medicine

145

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“…The large average b-hydrogen splitting obtained (2.13 mT) and the average b-phosphorus value (4.82 mT) are typical of the spin-trapping of a carbon-centered radical and can be compared to isotropic values obtained for (small) carbon-centered radicals. [27] Further evidence to support this conclusion was obtained from the results of an experiment in which a denaturing agent (urea, at a final concentration of 9 M) was added to the reaction mixture (after trapping). The resultant narrower and sharper spectrum of a less immobilized spin-adduct (characterized by decrease in the difference between the calculated A k and A ' values for nitrogen) and the typical b-hyperfine splittings, confirm that a carbon-centered radical is obtained (see Fig.…”

Section: Model Experiments: Characterization Of Depmpo Adducts Of Metmentioning

confidence: 71%

“…[36,37] These unusual conformational properties provide a highly distinctive EPR spectral pattern which is expected to be reflected in the spectra of peroxyl adducts. [27] We have previously demonstrated that analysis via automated spectral simulation of anisotropic or immobilized spectra (with appropriate nitrogen, hydrogen and phosphorus splittings) can substantially assist the process of obtaining averaged hyperfine splittings with which to characterize the spectra of macromolecular radicals or spectra recorded in frozen matrices. [38 -40] This method has been employed here in conjunction with an approach which employs frozen aqueous solutions, the latter providing further advantages including the increase in the signal-to-noise level (resulting from the increase in volume of the sample in the EPR cavity) and the increased stability anticipated for the peroxyl adducts at low temperature in a matrix.…”

Section: Introductionmentioning

confidence: 99%

Observation of Protein-derived (BSA) Oxygen-centered Radicals by EPR Spin-trapping Techniques

Clément

Gilbert

Rockenbauer

et al. 2002

Free Radical Research

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Electron paramagnetic resonance (EPR) spin-trapping experiments, employing the novel spin-trap DEPMPO, provide evidence for the formation of protein-peroxyl radicals from the reaction of bovine serum albumin (BSA) or lysozyme with HO. in the presence of O2. Spin-trapping leads to the detection of anisotropic spectra of partially immobilized protein-peroxyl spin-adducts; positive identification is based on a novel spectrum simulation approach (through which broadened anisotropic spectra are simulated and compared with experiment) and by comparison of results with those obtained when MeO2. is trapped and the adduct frozen in a solid matrix.

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31P Labeled Cyclic Nitrones: A New Class of Spin Traps for Free Radicals in Biological Milieu

Cited by 31 publications

References 29 publications

α- and β-Phosphorylated Amines and Pyrrolidines, a New Class of Low Toxic Highly Sensitive 31P NMR pH Indicators

α- and β-Phosphorylated Amines and Pyrrolidines, a New Class of Low Toxic Highly Sensitive 31P NMR pH Indicators

2-ethoxycarbonyl-2-methyl-3,4-dihydro-2H-pyrrole-1-oxide: evaluation of the spin trapping properties

Observation of Protein-derived (BSA) Oxygen-centered Radicals by EPR Spin-trapping Techniques

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