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
A novel series of 5-(5-nitrofuran-2-yl)-1,3,4-thiadiazol-2-amines were synthesized by introducing N-[(1-benzyl-1H-1,2,3-triazol-4-yl)methyl] moiety as a new functionality on the C-2 amine of thiadiazole ring via click chemistry. The title compounds namely, N-[(1-benzyl-1H-1,2,3-triazol-4-yl)methyl]-5-(5-nitrofuran-2-yl)-1,3,4-thiadiazol-2-amines (3a-n) were characterized by IR, NMR and MS spectra. These compounds were evaluated for their in vitro anti-leishmanial activity against promostigote form of the Leishmania major. Most compounds exhibited good anti-leishmanial activity against the promastigote form of L. major. The most active compound against promostigotes was found to be 4-methylbenzyl analog 3i, which significantly decreases the number of intracellular amastigotes per macrophage, percentage of macrophage infectivity and infectivity index.
Asunto(s)
Antiprotozoarios/síntesis química , Antiprotozoarios/farmacología , Leishmania major/efectos de los fármacos , Leishmaniasis/tratamiento farmacológico , Macrófagos Peritoneales/efectos de los fármacos , Tiadiazoles/síntesis química , Tiadiazoles/farmacología , Triazoles/síntesis química , Triazoles/farmacología , Animales , Células Cultivadas , Macrófagos Peritoneales/parasitología , Ratones , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Relación Estructura-ActividadRESUMEN
In order to optimize the antileishmanial activity of piperazinyl-linked 5-(5-nitrofuran-2-yl)-1,3,4-thiadiazoles, we synthesized a series of 5-(5-nitrofuran-2-y1)-1,3,4-thiadiazoles with piperazinyl-linked benzamidine substituent as scaffold found in pentamidine related antiprotozoals. The structure of target compounds was confirmed by IR, 1H NMR, 13C NMR and Mass spectral data. All compounds were tested for in vitro activity against the promastigote and amastigote forms of Leishmania major. From the results, we found that the substitution on amidine nitrogen has profound role in the biological activity of these compounds. The 5-nitrofuran-2-yl-1,3,4-thiadiazoles having n-propyl, n-butyl and benzyl side chain on benzamidine (as in compounds 2d, 2e and 2g, respectively) showed very good activity in both forms of promastigote and amastigote. The most active compound was N-propyl-4-(4-(5-(5-nitrofuran-2-yl)-1,3,4-thiadiazol-2-yl)piperazin-1-yl) benzamidine hydrochloride (2d) with IC50 value of 0.08 µM in promastigote model. This compound showed a very low level of toxicity against macrophages (CC50=785 µM), with the highest selectivity index (SI=78.5) among the tested compounds.