Antileishmanial activity of 5-nitroindazole derivatives.

Background: Currently, there is no safe and effective vaccine against leishmaniasis and existing therapies are inadequate due to high toxicity, cost and decreased efficacy caused by the emergence of resistant parasite strains. Some indazole derivatives have shown in vitro and in vivo activity against Trichomonas vaginalis and Trypanosoma cruzi. On that basis, 20 indazole derivatives were tested in vitro against Leishmania amazonensis. Objective: To evaluate the in vitro activity of twenty 2-benzyl-5-nitroindazolin-3-one derivatives against L. amazonensis. Design: For the selection of promising compounds, it is necessary to evaluate the indicators for in vitro activity. For this aim, a battery of studies for antileishmanial activity and cytotoxicity were implemented. These results enabled the determination of the substituents in the indazole derivatives responsible for activity and selectivity, through the analysis of the structure-activity relationship (SAR). Methods: In vitro cytotoxicity against mouse peritoneal macrophages and growth inhibitory activity in promastigotes were evaluated for 20 compounds. Compounds that showed adequate selectivity were tested against intracellular amastigotes. The SAR from the results in promastigotes was represented using the SARANEA software. Results: Eight compounds showed selectivity index >10% and 50% inhibitory concentration <1 µM against the promastigote stage. Against intracellular amastigotes, four were as active as Amphotericin B. The best results were obtained for 2-(benzyl-2,3-dihydro-5-nitro-3-oxoindazol-1-yl) ethyl acetate, with 50% inhibitory concentration of 0.46 ± 0.01 µM against amastigotes and a selectivity index of 875. The SAR study showed the positive effect on the selectivity of the hydrophilic fragments substituted in position 1 of 2-benzyl-5- nitroindazolin-3-one, which played a key role in improving the selectivity profile of this series of compounds. Conclusion: 2-bencyl-5-nitroindazolin-3-one derivatives showed selective and potent in vitro activity, supporting further investigations on this family of compounds as potential antileishmanial hits.

Drug repositioning for novel antitrichomonas from known antiprotozoan drugs using hierarchical screening.

AIM: Metronidazole is the most widely used drug in trichomoniasis therapy. However, the emergence of metronidazole-resistant Trichomonas vaginalis isolates calls for the search for new drugs to counter the pathogenicity of these parasites. RESULTS: Classification models for predicting the antitrichomonas activity of molecules were built. These models were employed to screen antiprotozoal drugs, from which 20 were classified as active. The in vitro experiments showed moderate to high activity for 19 of the molecules at 10 µg/ml, while 3 compounds yielded higher activity than the reference at 1 µg/ml. The 11 most active chemicals were evaluated in vivo using Naval Medical Research Institute (NMRI) mice. CONCLUSION: Benznidazole showed similar results as metronidazole, and can thus be considered as a potential candidate in antitrichomonas therapy.

Descubrimiento de nuevos antimaláricos a partir de fármacos conocidos mediante cribado in silico e in vitro / Discovery of new antimalarials from commercial drugs by in silico and in vitro screening

Existe una urgente necesidad de descubrir nuevas alternativas terapéuticas para el tratamiento de la Malaria, dado que los fármacos disponibles en la actualidad muestran una alta toxicidad así como elevados niveles de resistencia. En el presente trabajo se ha diseñado un protocolo de cribado virtual constituido por diferentes filtros computacionales con el propósito de identificar nuevos núcleos bases antimaláricos a partir de una biblioteca estructuralmente diversa. Este procedimiento retuvo 38 nuevos hit virtuales de los cuales 12 fueron evaluados experimentalmente frente a Plasmodium falciparum, mostrando 3 de ellos actividad antipalúdica y ninguno mostró citotoxicidad inespecífica. Estos compuestos pueden considerarse como nuevos compuestos líderes, dejando una puerta abierta al desarrollo de nuevos antimaláricos(AU)

Increased efforts in antimalarial drug discovery are urgently needed. This paper applies a virtual screening protocol consisting of different computational filters in order to identify new antimalarial scaffolds from a structurally diverse library. This procedure has retained 38 new virtual hit which 12 were selected for experimental evaluation against Plasmodium falciparum, 3 of them showed significant antimalarial activity. These compounds have diverse chemical structures unrelated to existing antimalarial drugs can therefore be considered as new lead compounds, which leave an open door to the development of new antimalarials(AU)