Chagas disease, a chronic and silent disease caused by Trypanosoma cruzi, is currently a global public health problem. The treatment of this neglected disease relies on benznidazole and nifurtimox, two nitroheterocyclic drugs that show limited efficacy and severe side effects. The failure of potential drug candidates in Chagas disease clinical trials highlighted the urgent need to identify new effective chemical entities and more predictive tools to improve translational success in the drug development pipeline. In this study, we designed a small library of pyrazole derivatives (44 analogs) based on a hit compound, previously identified as a T. cruzi cysteine protease inhibitor. The in vitro phenotypic screening revealed compounds 3g, 3j, and 3m as promising candidates, with IC50 values of 6.09 ± 0.52, 2.75 ± 0.62, and 3.58 ± 0.25 µM, respectively, against intracellular amastigotes. All pyrazole derivatives have good oral bioavailability prediction. The structure–activity relationship (SAR) analysis revealed increased potency of 1-aryl-1H-pyrazole-imidazoline derivatives with the Br, Cl, and methyl substituents in the para-position. The 3m compound stands out for its trypanocidal efficacy in 3D microtissue, which mimics tissue microarchitecture and physiology, and abolishment of parasite recrudescence in vitro. Our findings encourage the progression of the promising candidate for preclinical in vivo studies.
A series of 28 hybrids pyrazole‐imidazolines 1a–n and 2a–n were synthesized by a new methodology using microwave irradiation, in short time (20–30 min), in low power (50–70 W), and in 34–92% yield. Among all methodologies evaluated, no side products were obtained. All derivatives were completely characterized by FT–IR, 1H and 13C NMR, GC–MS, and HRMS.
Background:
A series of new eight 2-(1-aryl-3-methyl-1H-pyrazol-4-yl)-1,4,5,6-tetrahydropyrimidines 1(a-h) were synthesized by microwave irradiation technique. In vitro phenotypic screening was performed to evaluate the effect of these compounds on intracellular amastigotes forms of Trypanosoma cruzi, the etiological agent of Chagas disease.
Methods:
Compounds 1(a-h) were synthesized from pyrazole-carbonitriles 2(a-h) employing microwave irradiation (50W) for 10-20 minutes. Physicochemical properties were calculated using OSIRIS DataWarrior. The toxic effect on mammalian cells (Vero Cells) and the trypanocidal activity against Trypanosoma cruzi (Dm28c-Luc) were also evaluated.
Results:
Compounds 1(a-h) were obtained in 24-94% yields. They were completely characterized by Fourier Transform Infrared (FT-IR), Nuclear Magnetic Resonance (NMR) and High-Resolution Mass Spectrometry (HRMS) analyses. The derivatives showed low trypanocidal activity, with IC50 ranging from 47.16 to > 100 µM, with lower activity than benznidazole(1.93 µM) used as reference drug.
Conclusion:
The attractive features of this synthetic methodology are mild conditions, short reaction time, and low power. All derivatives showed low toxicity in mammalian cells, good oral bioavailability, and did not violate Lipinski´s rule of 5.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.