Dissociation and electrooxidation of primaquine diphosphate as an approachto the study of anti-chagas prodrugs mechanism of action

This paper describes the voltammetric behavior of primaquine as a previous support to the further understanding of the delivery and action mechanisms of its respective synthesized prodrugs. There are few papers describing the drug behavior and most of the time no correlation between oxidation proces s and pH is done. Our results showed that primaquine oxidation is a one-ste p reaction involving two electrons with the charge transfer process being s trongly pH-dependent in acid medium and pH-independent in a weak basic medi um, with the neutral form being easily oxidized. This leads to the conclusion that quinoline nitrogen ring neutralization is a determinant step to the formation of the oxidized primaquine form. The e xistence of a relationship between the primaquine dissociation equilibrium and its electrooxidation process is shown. This work points the importance of voltammetric methodology as a tool for f urther studies on quantitative relationship studies between chemical struct ure and biological activity (QSAR) for electroactive drugs. (C) 2000 Elsevi er Science S.A. All rights reserved.