Electrochemical and spectroelectrochemical behavior of the main photodegradation product of nifedipine: The nitrosopyridine derivative

Nunez-Vergara, LJ; Bollo, S; Fuentealba, J; Sturm, JC; Squella, JA

Abstract

Purpose. To characterize the electrochemical behavior of the photodegradation product of nifedipine, i.e., 2,6-dimethyl-4-(2-nitrosophenyl)-3,5-pyridine-carboxylic acid dimethyl ester (NPD) in different electrolytic media. We also evaluated the interaction between free radicals generated from NPD and xeno/endobiotics. Methods. Tast polarography, differential pulse polarography, and cyclic voltammetry were used for the characterization. Controlled potential electrolysis and ultraviolet-visible spectroscopy were used to generate and to detect the nitroso radical anion. Results. In protic media, the NPD derivative gave a reversible well-defined peak either on Hg or glassy carbon electrodes in a reaction involving two electrons and two protons to give the hydroxylamine derivative. In mixed aqueous-organic media (pH 9) and in aprotic media, nitroso radical anion was isolated and characterized, exhibiting second-order dimerization rate constant (k2) values of 11,300 ± 210 [Ms]-1 and 8,820 ± 78 [Ms]-1, respectively. Reactivity of the nitroso radical anion with relevant pharmacologic targets revealed a significant interaction with the tested endo/xenobiotics (cysteamine, GSH, N-acetylcysteine, and adenine). Conclusions. Both in mixed and aprotic media, NPD generated free-radical species, the nitroso radical anion. Taking into account their respective interaction rate constants, the following tentative rank order of reactivity can be established as follows: cysteamine > N-acetylcysteine > GSH > adenine.

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Título según WOS: Electrochemical and spectroelectrochemical behavior of the main photodegradation product of nifedipine: The nitrosopyridine derivative
Título según SCOPUS: Electrochemical and spectroelectrochemical behavior of the main photodegradation product of nifedipine: The nitrosopyridine derivative
Título de la Revista: PHARMACEUTICAL RESEARCH
Volumen: 19
Número: 4
Editorial: SPRINGER/PLENUM PUBLISHERS
Fecha de publicación: 2002
Página de inicio: 522
Página final: 529
Idioma: English
Notas: ISI, SCOPUS