Avaliação da atividade tripanocida e da segurança terapêutica de um composto benzofuroxano derivado

Abstract

Chagas disease affects more than 8 million people worldwide and is caused by the flagellated protozoan Trypanosoma cruzi, which belongs to the Trypanosomatidae family. This parasite has a heteroxenous biological cycle with different evolutionary forms within its hosts. Chagas disease is a major public health concern in Brazil and Latin America and has been described as one of the most neglected diseases in the world. Even after more than a hundred years since its discovery, there is no safe and totally effective treatment for this disease; only two drugs, benznidazole and nifurtimox, are currently available to treat Chagas disease. Both drugs are highly toxic and have several side effects. In addition, the use of nifurtimox is prohibited in Brazil. Thus, the search for new drugs for this disease is necessary. The objectives of this study were to synthesize a benzofuroxane compound and evaluate its cytotoxicity and genotoxicity in vitro and to evaluate its trypanocidal activity in vitro and in vivo against T. cruzi. 5-((5-(4-Methoxyphenyl)-1,3,4-oxadiazol-2-yl)carbamoyl)benzo[c][1,2,5]oxadiazole-N-oxide was synthesized by our collaborator, LabSelen Nanobio (UFSM), and is referred to as compound EA2. The compound was characterized by 1H and 13C NMR. Its cytotoxicity was determined using the trypan blue exclusion method, and its genotoxicity was determined using the alkaline comet assay. Mutagenicity was evaluated using the micronucleus test. For these tests, three different concentrations of EA2 were used: 10 μM/mL, 50 μM/mL, and 100 μM/mL. The compound did not show any mutagenic activity at any of the concentrations tested. Moreover, only 10 μM/mL EA2 did not show cytotoxic or genotoxic effects. For the in vitro test against epimastigost forms of T. cruzi, the compound was used at three different concentrations (0.25%, 0.50%, and 1%) and the effects were evaluated after 24, 48, and 72 h of incubation. EA2 showed trypanocidal activity in vitro at all three concentrations. Subsequently, an in vivo test was performed using three different doses: 2.5 mg/kg, 5 mg/kg and 10 mg/kg. Test animals were divided into ten groups (5 animals per group): four groups consisting of uninfected (A, G, H, I) and six groups of infected (B, C, D, E, F, J) animals. Groups B and J were the negative and positive controls, respectively. Groups G, H, and I were used to demonstrate that the compound was not toxic to healthy animals. EA2 did not show any curative effects in vivo, but it was able to delay the onset of parasitemia in the treated animals as well as significantly reduce the parasite count in groups D and E. In addition, the compound did not alter hematological parameters or affect the liver and kidneys of uninfected animals, indicating that EA2 is not toxic. Nevertheless, further tests are necessary to prove the therapeutic safety of EA2.