Avaliação do Efeito anti-Leishmania de derivados mesoiônicos de 1,3,4 tiadiazólio sobre L.amazonensis in vitro

Abstract

Leishmaniasis is a group of diseases which affect millions of people annually around world mainly in the population in economic vulnerability, for this reason, this disease is part of a group of neglected diseases. Leishmaniasis is caused by protozoa of the Leishmania genus and transmitted to several mammals, including the man and domestic dog, by diptera belonging to the Lutzomyia and Phlebotomus genus. Its clinical manifestations vary according to the species of infected mammal, presenting in humans a broad clinical spectrum, and visceral-cutaneous manifestations in the dog. Drugs used in treatment have high production costs and a high toxicity, presents several side effects. In addition, in endemic countries, resistant strains have been reported. Therefore, the search for new bioactive molecules is necessary. Mesoionic salts are a subclass of the betaine group, widely studied by the pharmaceutical industry since the 1950s, and exhibit extensive biological activity. Our work aims to analyze the cytotoxic effects of three mesoionic compounds, MI-4 Cl (4-phenyl-5- (4-chloro-phenyl) -1,3,4-thiadiazolium-2-phenylamine), MI-3,4 diCl (4-phenyl-5- (3,4-dichloro-phenyl) -1,3,4-thiadiazolium-2-phenylamine) and MI-3,4 diF (4-phenyl-5- (3,4-difluor-phenyl ) -1,3,4-thiadiazolium-2-phenylamine), on Leishmania amazonensis in vitro. To evaluate the anti-promastigote effect, L. amazonensis promastigotes were incubated with different concentrations of mesoionic salts during 72 hours. Our results show that the mesoionic salts MI-3.4 diCl, MI-4Cl and MI-3.4 diF were toxic, with IC50/48 h values of 14.3, 40.1 and 61.8 μM, respectively. The anti-amastigote effect was evaluated in infected macrophages, and results demonstrate that chlorine compounds have a toxic effect against amastigotes present IC50/24 h of 33 μM (MI-4Cl) and 43 μM (MI-3.4diCl). None of the mesoionic compounds tested present host cell toxicity up to the tested concentration of 100 μM. Nitric oxide (NO) production in macrophages stimulated or not with LPS in the presence of the salts showed that only the MI-3.4 diCl compound reduced 2 times the NO levels. Lipid profile analysis of treated-promastigotes showed no alteration of neutral lipids. Mitochondrial membrane potential evaluation showed that MI-4Cl compound was the only one able to reduce mitochondrial membrane potential by 50%. Therefore, the results suggest that the mesoionic salts MI-4Cl and MI-3,4diCl have a potential anti-Leishmania effect