Antileishmanial Thioureas: Synthesis, Biological Activity and in Silico Evaluations of New Promising Derivatives.

Leishmaniasis is a neglected tropical disease caused by protozoan parasites belonging to the genus Leishmania. Currently, the drugs available for treatment of this disease present high toxicity, along with development of parasite resistance. In order to overcome these problems, efforts have been made to search for new and more effective leishmanicidal drugs. The aim of this study was to synthesize and investigate the leishmanicidal effect of N,N'-disubstituted thioureas against Leishmania amazonensis, with evaluation of their in silico pharmacokinetics and toxicity profiles. Our results showed that different thioureas could be obtained in high to moderate yields using simple reaction conditions. Nine thiourea derivatives (3e, 3i, 3k, 3l, 3p, 3q, 3v, 3x and 3z) were active against parasite promastigotes (IC50 21.48-189.10 µM), with low cytotoxicity on mice peritoneal macrophages (CC50>200 µM), except for thiourea 3e (CC50=49.22 µM). After that, the most promising thioureas (3k, 3l, 3p, 3q and 3v) showed IC50 ranging from 70 to 150 µM against L. amazonensis amastigotes in infected macrophages. Except for thiourea 3p, the leishmanicidal activity of the derivatives were independent of nitric oxide (NO) production. Thioureas 3q and 3v affected promastigotes cell cycle without disturbing the mitochondrial membrane potential. Furthermore, our derivatives showed satisfactory theoretical absorption, distribution, metabolism, excretion, toxicity (ADMET) properties. These data indicate that thiourea derivatives are good candidates as leading compounds for the development of new leishmanicidal drugs.

Design, Synthesis and Evaluation of New Fluoroamodiaquine Analogues.

Malaria is one of the most important tropical diseases; the use of amodiaquine as a current chemotherapy in the treatment of malaria has shown some problems such as hepatotoxicity and agranulocytosis. In this work we present the rational design, synthesis, and biological evaluation (antimalarial activity, cytotoxicity and genotoxicity) of four new fluoroamodiaquine analogues. The results showed significant correlation between MolDock score and IC50 values. The molecules 7b and c were the most active of the planned compounds, with lower IC50 against Plasmodium falciparum W2 strain (0.9 and 0.8 µM, respectively) and an excellent cytotoxicity profile. The present study revealed no mutagenicity or genotoxicity for the analogues. Confirming our docking results, the molecular dynamics showed that compound 7b remains stably bound to the heme group by means of π-stacking interactions between quinoline and the porphyrin ring. Based on these findings, this study may prove to be an efficient approach for the rational design of hemozoin inhibiting compounds to treat malaria.