REACTIVITY OF THE ONE-ELECTRON REDUCTION PRODUCT FROM NIMODIPINE, NITRENDIPINE AND NICARDIPINE WITH RELEVANT BIOLOGICAL THIOLS

The reactivity of the electrochemically generated nitro radical anion from nicardipine, nitrendipine and nimodipine, all nitro aryl 1,4-dihy dropyridine derivative, with relevant thiols, was quantitatively asses sed by cyclic voltammetry. The method was based in the decrease in the return-to-forward peak current ratio after the addition of the compou nds. A quantitative procedure to calculate the respective interaction constants between the radicals and the thiols was employed. In the opt imal selected conditions, i.e. mixed media (0.015 M aqueous citrate/DM F: 35/65, 0.3 M KCl, 0.1 TBAI) at pH 9.0 the following tentative order of reactivity of thiols could be established: glutathion > penicillam ine > N-acetylcysteine > captopril. Apparently, the nitro radical anio n from nicardipine was more reactive towards the thiol compounds than the other radicals. In all the cases, the interaction rate constants f or these derivatives were greater than the natural decay constant of t he radical. Results from these experiments indicate that cytotoxic int ermediates generated from the nitro aryl 1,4-dihydropyridine derivativ es can be efficiently scavenged by the studied thiols.