Trypanocidal activity of tioamide-sustituted imidazoisoquinolinones: Electrochemical properties and biological effects

Abstract

Three thioamide-substituted imidazoisoquinolinones, which possess an heterocyclic center similar to tryptanthrin and are named C1, C2 and C3, were studied regarding: a) its in vitro anti-Trypanosoma cruzi activity, b) its cytotoxicity and electrochemical behaviour and c) its effect on cell viability, redox state and mitochondrial function . The assayed compounds showed a significant activity against the proliferative forms, but only C1 showed activity on the trypomastigote form (for C1, IC50 epi = 1.49 µM; IC50 amas = 1.74 µM and IC50 try = 34.89 µM). The presence of an antioxidant compound such as ascorbic acid or dithiotreitol induced a three-fold increase in the antiparasitic activity, whereas glutathione had a dual effect depending on its concentration. Our results indicate that these compounds, which exhibited low toxicity to the host cells, can be reduced inside the parasite by means of the pool of low molecular weight thiols, causing oxidative stress and parasite death by apoptosis. The antiparasitic activity of the compounds studied could be explained by a loss of the capacity of the antioxidant defense system of the parasite to keep its intracellular redox state. C1 could be considered a good candidate for in vivo evaluation .