In Vitro and In Vivo Trypanosomicidal Action of Novel Arylimidamides against Trypanosoma cruzi.

Arylimidamides (AIAs) have been shown to have considerable biological activity against intracellular pathogens, includingTrypanosoma cruzi, which causes Chagas disease. In the present study, the activities of 12 novel bis-AIAs and 2 mono-AIAs against different strains ofT. cruziin vitroandin vivowere analyzed. The most active wasm-terphenyl bis-AIA (35DAP073), which had a 50% effective concentration (EC50) of 0.5 µM for trypomastigotes (Y strain), which made it 26-fold more effective than benznidazole (Bz; 13 µM). It was also active against the Colombiana strain (EC50= 3.8 µM). Analysis of the activity against intracellular forms of the Tulahuen strain showed that this bis-AIA (EC50= 0.04 µM) was about 100-fold more active than Bz (2 µM). The trypanocidal effect was dissociated from the ability to trigger intracellular lipid bodies within host cells, detected by oil red labeling. Both an active compound (35DAP073) and an inactive compound (26SMB060) displayed similar activation profiles. Due to their high selectivity indexes, two AIAs (35DAP073 and 35DAP081) were moved toin vivostudies, but because of the results of acute toxicity assays, 35DAP081 was excluded from the subsequent tests. The findings obtained with 35DAP073 treatment of infections caused by the Y strain revealed that 2 days of therapy induced a dose-dependent action, leading to 96 to 46% reductions in the level of parasitemia. However, the administration of 10 daily doses in animals infected with the Colombiana strain resulted in toxicity, preventing longer periods of treatment. The activity of the combination of 0.5 mg/kg of body weight/day 35DAP073 with 100 mg/kg/day Bz for 10 consecutive days was then assayed. Treatment with the combination resulted in the suppression of parasitemia, the elimination of neurological toxic effects, and survival of 100% of the animals. Quantitative PCR showed a considerable reduction in the parasite load (60%) compared to that achieved with Bz or the amidine alone. Our results support further investigations of this class with the aim of developing novel alternatives for the treatment of Chagas disease.

[In vitro cytotoxicity of nitroxyl radicals with respect to tumor and diploid human cells and estimation of their antiviral activity].

Thirty nine water soluble nitroxyl radicals of various classes, belonging to piperidine, pyrrolidine and imidazolidine series were synthesized. Twenty seven of them were cytotoxic in vitro with respect to the tumor cell culture A431. The CC50 of the most active nitroxyl radicals with respect to cells SW480 and A431 was within 0.16-2.5 mM at the selectivity index of 3.91-7.81 in relation to cytotoxicity of the compounds for the cells of the normal L68 phenotype and tumor cells. The tests on the antiviral activity showed that 16 out of 22 nitroxyl radicals had antiviral activity in Vero cell culture with respect to the West Nile virus and Herpes simplex virus of type II respectively. The EC50 ranged within 0.09-3.45 mM. Some of the nitroxyl radicals had only antiviral activity, but a number of the compounds had both cytotoxic properties and antiviral activity.