Abstract
Purpose. To study the reactivity of C4-substituted 1,4-dihydropyri- dines (1,4-DHP), with either secondary or tertiary nitrogen in the dihydropyridine ring, toward SIN-1-derived peroxynitrite in aqueous media at pH 7.4.
Methods. Reactivity was followed by changes in the absorptivity of the UV-Vis bands corresponding to 1,4-DHP. Gas Chromatography/Mass Spectrometer (GC-MS) and Electron Paramagnetic Resonance (EPR) spin trap techniques were used to characterize the final product and the intermediates of the reaction, respectively.
Results. 1,4-DHPs significantly reacted toward peroxynitrite at varied rates, according to the calculated kinetic rate constants. By EPR spectroscopy, a carbon-centered radical from the 1,4-DHP was intercepted with N-tert-butylamine-α-phenylnitrone (PBN), as the intermediate for the reaction with peroxynitrite. Likewise, the oxidized derivative (i.e., the pyridine) was identified as the final product of the reaction by GC-MS. By using the technique of deuterium kinetic isotope effect, the participation of the hydrogen of the 1-position on the 1,4-DHP ring was shown not to be the rate-limiting step of the reaction.
Conclusions. The direct participation of the 1,4-DHP derivatives in the quenching of SIN-1-derived peroxynitrite has been demonstrated. Kinetic rate constant of tested 1,4-DHP toward peroxynitrite showed a direct relationship with the oxidation peak potential values; that is, compounds reacting faster were more easily oxidized.
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L#x00F3;pez-Alarc#x00F3;n, C., Speisky, H., Squella, J.A. et al. Reactivity of 1,4-Dihydropyridines Toward SIN-1-Derived Peroxynitrite. Pharm Res 21, 1750–1757 (2004). https://doi.org/10.1023/B:PHAM.0000045224.97323.8b
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DOI: https://doi.org/10.1023/B:PHAM.0000045224.97323.8b