RESUMEN
Under a variety of stress conditions, Leishmania species display some morphological and biochemical features characteristic of mammalian programmed cell death or necrosis. Nitroheteroaryl-1,3,4-thiadiazoles induce cell death in Leishmania major (L. major). Putative mechanisms of action of these compounds were investigated in vitro at cellular and molecular levels. We used colorimetric assay to measure acid phosphatase activity which is an indicator of cell viability in the promastigotes. The mode of toxicity was determined by detection of phosphatidylserine translocation to the surface, evaluation of cell membrane integrity, and in situ dUTP nick end-labeling assay. We also determined poly-ADP-ribose polymerase-like protein (PARP) level in the parasites after treatment. A significant reduction of acid phosphatase level, one of the most crucial and virulent factors of the parasite was found in parasites treated with 1,3,4-thiadiazole derivatives. In addition, 1,3,4-thiadiazole derivatives induced loss of plasma membrane integrity, DNA breakage, proteolysis of PARP and necrotic-like death in the parasites.
Asunto(s)
Leishmania major/efectos de los fármacos , Tiadiazoles/farmacología , Fosfatasa Ácida/análisis , Fosfatasa Ácida/efectos de los fármacos , Anexina A5 , Fragmentación del ADN/efectos de los fármacos , Dactinomicina/análogos & derivados , Citometría de Flujo , Colorantes Fluorescentes , Etiquetado Corte-Fin in Situ , Indicadores y Reactivos , Concentración 50 Inhibidora , Leishmania major/citología , Leishmania major/enzimología , Leishmania major/crecimiento & desarrollo , Poli(ADP-Ribosa) Polimerasas/análisis , Tiadiazoles/síntesis químicaRESUMEN
With the aim of determining selectivity and the possible target(s) of nitroheteroaryl-1,3,4-thiadiazoles considered as possible leads for the development of anti-leishmanial agents, we studied 5-nitroimidazole, 5-nitrofuran and 5-nitrothiophene analogs of N-substituted-piperazinyl-1,3,4-thiadiazoles. We investigated 21 representative compounds 1-3(a-g) for the following properties: selectivity and efficiency against different Leishmania wild type species and intracellular parasite, toxicity against host cells and inhibition of topoisomerases I and II. Our results indicate that the nitroimidazole analogs 1a and 1f, and nitrofuran derivatives 2a, 2b, 2c, 2f, and 2g exhibited low toxicity against the host cells (IC(50)> or =80 microM), but high selectivity against intracellular amastigotes (selectivity index>12). Leishmania topoisomerases revealed impressive sensitivity to the agents (%inhibition >50 at IC(50) doses of compounds against Leishmania). Our findings showed that at least part of leishmaniacidal effect of the compounds could be attributed to disruption DNA-relaxed activities of topoisomerases I and II, and cleavable-complex formation.
Asunto(s)
Antiprotozoarios/farmacología , Leishmania/efectos de los fármacos , Tiadiazoles/farmacología , Animales , Antiprotozoarios/química , Antiprotozoarios/toxicidad , Humanos , Concentración 50 Inhibidora , Leishmania/enzimología , Leishmania major/efectos de los fármacos , Leishmania major/enzimología , Macrófagos Peritoneales/efectos de los fármacos , Macrófagos Peritoneales/enzimología , Ratones , Ratones Endogámicos BALB C , Tiadiazoles/química , Tiadiazoles/toxicidad , Inhibidores de Topoisomerasa I , Inhibidores de Topoisomerasa IIRESUMEN
A series of 1-[5-(1-methyl-5-nitro-1H-imidazol-2-yl)-1,3,4-thiadiazol-2-yl]-4-aroylpiperazines were synthesized and evaluated in vitro against Leishmania major. Most of the target compounds exhibited good anti-leishmanial activity against the promastigote form of L. major at non-cytotoxic concentrations. The most active compound was 1-[(5-chloro-2-thienyl)carbonyl]-4-[5-(1-methyl-5-nitro-1H-imidazol-2-yl)-1,3,4-thiadiazol-2-yl]piperazine (5f) with an IC(50) value of 9.35+/-0.67 microM against L. major promastigotes. In addition, this compound was effective against intracellular L. major and significantly decreased the infectivity index.
Asunto(s)
Leishmania major/efectos de los fármacos , Tiadiazoles/síntesis química , Tiadiazoles/farmacología , Tripanocidas/síntesis química , Tripanocidas/farmacología , Animales , Diseño de Fármacos , Tiadiazoles/química , Tripanocidas/químicaRESUMEN
The synthesis and anti-leishmanial activity of nitroheteroaryl-1,3,4-thiadiazole-based compounds including 1-[5-(5-nitrofuran-2-yl)-1,3,4-thiadiazol-2-yl]-4-aroylpiperazines and 1-[5-(5-nitrothiophen-2-yl)-1,3,4-thiadiazol-2-yl]-4-aroylpiperazines were described. Most of the synthesized compounds exhibited potent anti-leishmanial activity against both promastigote and amastigote forms of Leishmania major at non-cytotoxic concentrations. In general, 5-nitrofuran derivatives were more active than the corresponding 5-nitrothiophene analogues.