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Titolo:
Cyclic voltammetric studies on nitro radical anion formation from megazol and some related nitroimidazole derivatives
Autore:
Bollo, S; Nunez-Vergara, LJ; Bonta, M; Chauviere, G; Perie, J; Squella, JA;
Indirizzi:
Univ Chile, Chem & Pharmaceut Sci Fac, Bioelectrochem Lab, Santiago 1, Chile Univ Chile Santiago Chile 1 i Fac, Bioelectrochem Lab, Santiago 1, Chile Univ Toulouse 3, CNRS, ESA 5068, Grp Chim Organ Biol, F-31062 Toulouse, France Univ Toulouse 3 Toulouse France F-31062 n Biol, F-31062 Toulouse, France
Titolo Testata:
JOURNAL OF ELECTROANALYTICAL CHEMISTRY
fascicolo: 1-2, volume: 511, anno: 2001,
pagine: 46 - 54
Fonte:
ISI
Lingua:
ENG
Soggetto:
TRYPANOSOMA-CRUZI INFECTIONS; AFRICAN TRYPANOSOMIASIS; CURATIVE ACTION; GLUTATHIONE; METABOLISM; PHARMACOKINETICS; GENERATION; REACTIVITY; EXCRETION; REDUCTION;
Keywords:
nitroimidazole derivatives; nitro radical anion; cyclic voltammetry;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
36
Recensione:
Indirizzi per estratti:
Indirizzo: Squella, JA Univ Chile, Chem & Pharmaceut Sci Fac, Bioelectrochem Lab, POB233, Santiago 1, Chile Univ Chile POB 233 Santiago Chile 1 OB 233, Santiago 1, Chile
Citazione:
S. Bollo et al., "Cyclic voltammetric studies on nitro radical anion formation from megazol and some related nitroimidazole derivatives", J ELEC CHEM, 511(1-2), 2001, pp. 46-54

Abstract

Megazol (2-amino-5-(1-methyl-5-nitro-2-imdazolyl)-1,3,4-thiadiazol, CAS 19622-55-0) and related nitroimidazole compounds are being tested as antichagasic drugs. Little is known on the mode of action of megazol. However, there is evidence that one-electron reduction of megazol to the corresponding nitro radical anion is a key step in the reaction mechanism. Consequently, this paper is focused on the cyclic voltammetric behaviour of megazol and related nitroimidazole derivatives with the aim of revealing the formation and stability of the corresponding nitro radical anions. All the compounds studied produce a well resolved nitro/nitro radical anion couple. The resolution of the couple was improved with the addition of tetrabutylammonium. ions which hinders the protonation of the nitro radical anion at the electrodesurface, thus enhancing the stability of the nitro radical anion. Only megazol produced a cyclic voltammogram distorted by the presence of a pre-peakdue to strong adsorption of the corresponding nitro radical anion. The pre-peak occurs at potentials more positive than the diffusion controlled peakbecause the Gibbs energy of adsorption of the nitro radical anion makes the reduction of megazol to the adsorbed nitro radical anion easier than to the radical anion in solution. The sulphur atom in the thiadiazole ring plays a crucial role in the adsorption phenomena. Using the cyclic voltammetry theory for the disproportionation reaction, we have calculated the second-order decay rate constant, k(2), and the half-life time, t(1/2), for all thenitro radical anions of the studied nitroimidazole derivatives. The valuesobtained were compared with those of the corresponding nitro radical anions obtained from nifurtimox and benznidazole, the classic antichagasic drugs. Also, our results show that cyclic voltammetry is a good alternative to the classic pulse radiolysis method to obtain reliable values of the E-7(1) parameter for nitro radical anions. (C) 2001 Elsevier Science B.V. All rights reserved.

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Documento generato il 03/04/20 alle ore 11:35:28