Search Results (5)

Chagas disease, caused by Trypanosoma cruzi, poses a significant public health challenge due to its widespread prevalence, limited therapeutic options, and adverse effects associated with available medications. In this study, we developed 13 novel pyrazole-imidazoline derivatives, inspired by a previously identified cysteine protease inhibitor, and evaluated their antiparasitic activity. Our in silico analyses predicted favorable physicochemical profiles and promising oral bioavailability for these derivatives. Upon phenotypic screening, we observed that these new derivatives exhibited low cytotoxicity (CC₅₀ > 100 µM) and marked efficacy against intracellular amastigotes. Derivative 1k showed high activity (IC₅₀ = 3.3 ± 0.2 µM), selectivity (SI = 73.9), and potency (pIC₅₀ = 5.4). In a 3D cardiac microtissue model, 1k significantly reduced parasite load, matching the efficacy of benznidazole (Bz) even at lower concentrations. Both 1k and Bz effectively prevented parasite recrudescence; however, neither resulted in parasite sterility under the experimental conditions employed. The combination of 1k–Bz yielded an additive interaction, highlighting its potential for in vivo combination therapy. While structural changes abolished cysteine protease inhibition, incorporating a CF₃ substituent at the para position and excluding the amino group enhanced antiparasitic activity. These findings reinforce the promise of the pyrazole-imidazoline scaffold and support further structural optimizations to develop innovative candidates for treating Chagas disease. Full article

New complexes of manganese(II) hexafluoroacetylacetonate [Mn(hfac)₂] with 2-(1-R-3-pyrazol-4-yl)-4,4,5,5-tetramethyl-2-imidazoline-3-oxide-1-oxyl (R = CHF₂, CH₂CH₂F, CH₂CHF₂ or CH₂CF₃) were synthesised and characterised structurally and magnetically. All complexes were prepared under similar conditions. Nonetheless, their crystal structures were considerably different. Depending on the structure of fluorinated alkyl substituent R, the complexation reaction led to complexes of three types: chain-polymeric complexes with the head-to-head or head-to-tail motif and complexes of molecular structure. All complexes show strong antiferromagnetic behaviour in a high-temperature region (150–300 K) and weak ferro- or antiferromagnetic exchange interactions at low temperatures. The stronger antiferromagnetic exchange, −101.7 ± 1.5 or −136 ± 10 cm⁻¹, −82.3 ± 1.3 cm⁻¹ and −87.4 ± 1.3 cm⁻¹, was attributed to the magnetic interaction in three- or two-spin clusters: {>N∸O–Mn²⁺–O∸N<} or {>N∸O–Mn²⁺}, respectively. The weaker antiferromagnetic interaction, −0.005, between three-spin clusters or ferromagnetic interactions, 0.18–0.81 cm⁻¹, between two-spin clusters are realised through the pyrazole ring or intermolecular contacts. Full article

Many heterocyclic compounds can be synthetized using diaza-1,3-butadienes (DADs) as key structural precursors. Isolated and in situ diaza-1,3-butadienes, produced from their respective precursors (typically imines and hydrazones) under a variety of conditions, can both react with a wide range of substrates in many kinds of reactions. Most of these reactions discussed here include nucleophilic additions, Michael-type reactions, cycloadditions, Diels–Alder, inverse electron demand Diels–Alder, and aza-Diels–Alder reactions. This review focuses on the reports during the last 10 years employing 1,2-diaza-, 1,3-diaza-, 2,3-diaza-, and 1,4-diaza-1,3-butadienes as intermediates to synthesize heterocycles such as indole, pyrazole, 1,2,3-triazole, imidazoline, pyrimidinone, pyrazoline, -lactam, and imidazolidine, among others. Fused heterocycles, such as quinazoline, isoquinoline, and dihydroquinoxaline derivatives, are also included in the review. Full article

Chagas disease, a century-old disease that mainly affects the impoverished population in Latin America, causes high morbidity and mortality in endemic countries. The available drugs, benznidazole (Bz) and nifurtimox, have limited effectiveness and intense side effects. Drug repurposing, and the development of new chemical entities with potent activity against Trypanosoma cruzi, are a potential source of therapeutic options. The present study describes the biological activity of two new series of pyrazole-thiazoline derivatives, based on optimization of a hit system 5-aminopyrazole-imidazoline previously identified, using structure–activity relationship exploration, and computational and phenotype-based strategies. Promising candidates, 2c, 2e, and 2i derivatives, showed good oral bioavailability and ADMET properties, and low cytotoxicity (CC₅₀ > 100 µM) besides potent activity against trypomastigotes (0.4–2.1 µM) compared to Bz (19.6 ± 2.3 µM). Among them, 2c also stands out, with greater potency against intracellular amastigotes (pIC₅₀ = 5.85). The selected pyrazole-thiazoline derivatives showed good permeability and effectiveness in the 3D spheroids system, but did not sustain parasite clearance in a washout assay. The compounds’ mechanism of action is still unknown, since the treatment neither increased reactive oxygen species, nor reduced cysteine protease activity. This new scaffold will be targeted to optimize in order to enhance its biological activity to identify new drug candidates for Chagas disease therapy. Full article

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. Full article