In vitro genotoxicity of nitroimidazoles as a tool in the search of new trypanocidal agents

Abstract

BACKGROUND Only benznidazole (Bnz) (1) and nifurtimox (Nfx) (2) are licensed for the treatment of Chagas disease although their safety and efficacy profile are far from ideal. Farmanguinhos from Fiocruz has developed seven nitroimidazole compounds (4-10) analogs of megazol (3). OBJECTIVES To evaluate whether the genotoxic effect of 3 was abolished in the seven nitroimidazoles (4-10) analogs using the in vitro alkaline comet assay (CA) and the in vitro cytokinesis-block micronucleus assay (CBMN) in whole human blood cells (WHBC) and correlate this effect with their trypanocidal activity using bloodstream trypomastigote forms of Trypanosoma cruzi . METHODS The toxicity of 3-10 to WHBC in the in vitro CA was determined using the fluorescein diacetate/ethidium bromide assay. DNA damage in the in vitro CA was evaluated according to tail size in four classes (0-3) and methyl methane-sulfonate (MMS) was used as a positive control. The cytotoxicity of 3-10 to WHBC in the CBMN was measured using the cytokinesis-block proliferation index and the replication index. The number of the micronucleate cells in 2,000 binucleate cells by experimental group was determined. Mitomycin C and N-deacetyl-N-methylcolchicine were used as positive controls. FINDINGS Compound 3 showed a significant DNA strand break effect through the in vitro CA and highly significant clastogenic and/or aneugenic effect in the CBMN. Compounds 5, 6, 8, 9 and 10 showed negative results in the CBMN and positive results in the in vitro CA, while the inverse effect was observed for 4 and 7. MAIN CONCLUSIONS Compound 10 was the most promising to proceed with the development as a drug candidate in the treatment of Chagas disease showing absence of chromosomal cytogenetic damage and high activity against T. cruzi , about two times higher than 3 and the clinical drug 1.

Imidazole and nitroimidazole derivatives as NADH‐fumarate reductase inhibitors: Density functional theory studies, homology modeling, and molecular docking

“…This disease is transmitted mainly by the bite of triatomines, but can also be transmitted congenitally, by transplants, blood transfusions, among other forms 1,7 . The only drugs approved by the WHO for its treatment are two nitroaromatic compounds: nifurtimox and benznidazole (BNZ), which are effective if they are administered at the onset of the infection; however, it has been reported that their effectiveness decreases and their toxicity increases in long‐term treatments, which makes them banned in many countries 1,2,8–10 . Such toxicity relates to the formation of free radicals generated by the reduction of the nitro group, which puts the parasite under oxidative stress and causes its death, but also causes damage to human cells.…”

“…effective if they are administered at the onset of the infection; however, it has been reported that their effectiveness decreases and their toxicity increases in long-term treatments, which makes them banned in many countries. 1,2,[8][9][10] Such toxicity relates to the formation of free radicals generated by the reduction of the nitro group, which puts the parasite under oxidative stress and causes its death, but also causes damage to human cells. Nevertheless, in the literature it has been reported that the antichagasic effect of BNZ does not depend on the production of free radicals and can act against the parasite in different ways, so its main mechanism of action is still unknown.…”

Diseño de derivados del imidazol como inhibidores de NADH-fumarato reductasa de Trypanosoma cruzi

“…Actualmente, la Organización Mundial de la Salud la ha clasificado dentro de la lista de las enfermedades tropicales desatendidas más importantes del mundo, con presencia en 21 países de América Latina, como: Belice, Bolivia, Chile, Colombia, Costa Rica, Ecuador, El Salvador, Guyana Francesa, Guatemala, Guyana, Honduras, Nicaragua, Panamá, Paraguay, Perú, Suriname, Uruguay, Venezuela, Argentina, Brasil, y México [WHO, 2022;DNDI, 2022], donde, estos últimos, ocupan los tres primeros lugares en relación al número de infectados [WHO, 2015]. Sin embargo, debido a la migración, la enfermedad de Chagas también se ha encontrado en otros países y continentes, como: Estados Unidos de Norteamérica (con aproximadamente 300,000 personas infectadas) [FDA, 2017], Canadá, Japón, Australia y diversos países europeos, con lo cual, se ha colocado como un importante problema de salud pública para el resto del mundo [WHO, 2022;DNDI, 2022;Von Trompowsky, 2019;Merlino, 2014].…”

“…El benznidazol es un nitroimidazol que es fabricado por el Laboratorio Farmacéutico del Estado de Pernambuco (de Brasil), por el Laboratorio Elea (de Argentina) y por Chemo Research, S. L. (de España) [Von Trompowsky, 2019;FDA, 2017]. Su acción está dada por diferentes rutas, las cuales tienen efecto sobre la síntesis del ácido desoxirribonucleico (DNA, por sus siglas en inglés) del parásito Trypanosoma cruzi.…”

“…Esta enfermedad se transmite principalmente por la picadura de triatominos, pero también puede transmitirse de forma congénita, por trasplantes, transfusiones de sangre, entre otros [WHO, 2022;Izquierdo, 2021]. Los únicos fármacos aprobados por la OMS para su tratamiento son el nifurtimox (NFX) y el benznidazol (BNZ), los cuales son efectivos si se administran al inicio de la infección; sin embargo, se ha reportado que en tratamientos largos su efectividad disminuye y su toxicidad aumenta, por lo cual su venta ha sido prohibida en la mayoría de los países [WHO, 2022;DNDI, 2022;Von Trompowsky, 2019;Ribeiro, 2020;Bern, 2015]. Dicha toxicidad se relaciona con la formación de radicales libres generados por la reducción del grupo nitro, la cual somete al parásito a un estrés oxidativo que provoca su muerte, pero al mismo tiempo, esta oxidación causa daños en las células humanas.…”