Abstract

Purpose. To evaluate the reaction of a large series of pharmacologically significant 1,4-dihydropyridine (1,4-DHP) compounds with superoxide (O2-) in dimethylsulfoxide using differential pulse voltammerry and controlled potential electrolysis. Methods. Differential pulse voltammetry was used to track the consumption of O2-, and controlled potential electrolysis was used to electrogenerate O2-. Results. With the addition of 1,4-DHP, the oxidation peak current of O2- decreased concentration dependently, suggesting that 1,4-DHP reacts with O2-, that is, 1,4-DHP scavenges O2- in dimethylsulfoxide. Conclusions. A very easy and direct voltammetric procedure to study the relative reactivity of different 1,4-DHP with O2- is proposed. Using the proposed method we have found that all commercial 1,4-DHP reacts with O2-. The following order of rates was obtained: felodipine ? vitamin E > isradipine > nimodipine > furnidipine > nitrendipine > nisoldipine > nifedipine. Furthermore, it was demonstrated that the hydrogen at the N-position of 1,4-DHP compounds could be released as a proton in the presence of O2-, thus the electrogenerated O2- worked as a proton acceptor to 1,4-DHP.