anti-Trypanosoma Cruzi Agents Research Articles

5-Nitroindazole-based compounds: further studies for activity optimization as anti-Trypanosoma cruzi agents

In this study, a new series of eleven 5-nitroindazole derivatives (10−20) and a related 6-nitroquinazoline (21) was synthesized and tested in vitro against different forms of the kinetoplastid parasite Trypanosoma cruzi, etiological agent of Chagas disease. Among these compounds, derivatives 11−14 and 17 showed trypanocidal profiles on epimastigotes (IC50 = 1.00−8.75 µM) considerably better than that of the reference drug benznidazole, BZ (IC50 = 25.22 µM). Furthermore, the lack of cytotoxicity observed for compounds 11, 12, 14, 17 and 18 over L929 fibroblasts, led to a notable selectivity (SI) on the extracellular replicative form of the parasite: SIEPI > 12.41 to > 256 µM. Since these five derivatives overpassed the cut-off value established by BZ (SIEPI ≥ 10), they were moved to a more specific assay against the intracellular and replicative form of T. cruzi, i.e, amastigotes. These molecules were not as active as BZ (IC50 = 0.57 µM) against this parasite form; however, all of them showed remarkable IC50 values lower than 7 µM. Special mention deserve compounds 12 and 17, whose SIAMA were > 246.15 and > 188.23, respectively. The results compiled in the present work, point to a positive impact over the trypanocidal activity of the electron withdrawing substituents introduced at position 2 of the N-2 benzyl moiety of these compounds, especially fluorine, i.e., derivatives 12 and 17. These outcomes, supported by the in silico prediction of good oral bioavailability and suitable risk profile, reinforce the 5-nitroindazole scaffold as an adequate template for preparing potential antichagasic agents.

6-Methyl-7-Aryl-7-Deazapurine Nucleosides as Anti-Trypanosoma cruzi Agents: Structure-Activity Relationship and in vivo Efficacy.

Chagas disease is a tropical infectious disease resulting in progressive organ-damage and currently lacks efficient treatment and vaccine options. The causative pathogen, Trypanosoma cruzi, requires uptake and processing of preformed purines from the host because it cannot synthesize these de novo, instigating the evaluation of modified purine nucleosides as potential trypanocides. By modifying the pyrimidine part of a previously identified 7-aryl-7-deazapurine nucleoside, we found that substitution of a 6-methyl for a 6-amino group allows retaining T. cruzi amastigote growth inhibitory activity but confers improved selectivity towards mammalian cells. By keeping the 6-methyl group unaltered, and introducing different 7-aryl groups, we identified several analogues with sub-micromolar antitrypanosomal activity. The 7-(4-chlorophenyl) analogue 14, which was stable in microsomes, was evaluated in an acute mouse model. Oral administration of 25 mg/kg b.i.d. suppressed peak parasitemia and protected mice from infection-related mortality, gave similar reductions as the reference drug of blood parasite loads determined by qPCR, but as benznidazole failed to induce sterile cure in the short time period of drug exposure (5 days).

Naturally Occurring Alkaloids, Derivatives, and Semi-synthetic Modifications as Lead Compounds for the Development of New Anti-Trypanosoma cruzi Agents

Despite recent advances, Chagas disease is still a public health issue that requires more efforts in order to develop efficient and safe drugs. Plants and fungi are the main source for semi-synthetic natural-inspired new molecules to treat human illness. In the present work, we summarize the main findings of natural-derived and semi-synthetic alkaloids against Trypanosoma cruzi. Over the last 10 years, at least seven alkaloids groups with structural modifications, including 130 molecules and almost 100 semi-synthetic compounds derived from natural alkaloids, including hybrids molecules, modifications of aliphatic chain extension, chemical groups, and heteroatoms, were analyzed for its toxicity over parasites and mammalian cells. According to the available data, there are a good number of promising natural and/or semi-synthetic alkaloids that would meet the criteria to become candidates in the drug discovery process against Trypanosoma cruzi parasites. Main scaffolds that deserve special attention are natural quinolones, isoquinolines, and semi-synthetic hybrids molecules.

Dual Parasiticidal Activities of Phthalimides: Synthesis and Biological Profile against Trypanosoma cruzi and Plasmodium falciparum.

Chagas disease and malaria are two neglected tropical diseases (NTDs) that prevail in tropical and subtropical regions in 149 countries. Chagas is also present in Europe, the US and Australia due to immigration of asymptomatic infected individuals. In the absence of an effective vaccine, the control of both diseases relies on chemotherapy. However, the emergence of parasite drug resistance is rendering currently available drugs obsolete. Hence, it is crucial to develop new molecules. Phthalimides, thiosemicarbazones, and 1,3-thiazoles have been used as scaffolds to obtain antiplasmodial and anti-Trypanosoma cruzi agents. Herein we present the synthesis of 24 phthalimido-thiosemicarbazones (3 a-x) and 14 phthalimido-thiazoles (4 a-n) and the corresponding biological activity against T. cruzi, Plasmodium falciparum, and cytotoxicity against mammalian cell lines. Some of these compounds showed potent inhibition of T. cruzi at low cytotoxic concentrations in RAW 264.7 cells. The most active compounds, 3 t (IC50 =3.60 μM), 3 h (IC50 =3.75 μM), and 4 j (IC50 =4.48 μM), were more active than the control drug benznidazole (IC50 =14.6 μM). Overall, the phthalimido-thiosemicarbazone derivatives were more potent than phthalimido-thiazole derivatives against T. cruzi. Flow cytometry assay data showed that compound 4 j was able to induce necrosis and apoptosis in trypomastigotes. Analysis by scanning electron microscopy showed that T. cruzi trypomastigote cells treated with compounds 3 h, 3 t, and 4 j at IC50 concentrations promoted changes in the shape, flagella, and surface of the parasite body similar to those observed in benznidazole-treated cells. The compounds with the highest antimalarial activity were the phthalimido-thiazoles 4 l (IC50 =1.2 μM), 4 m (IC50 =1.7 μM), and 4 n (IC50 =2.4 μM). Together, these data revealed that phthalimido derivatives possess a dual antiparasitic profile with potential effects against T. cruzi and lead-like characteristics.

In vitro and in silico evaluations of new aryloxy-1,4-naphthoquinones as anti-Trypanosoma cruzi agents

In the search for new therapeutic alternatives for Chagas disease, a series of six aryloxy -naphthoquinone derivatives were synthesized and evaluated in vitro against Trypanosoma cruzi epimastigotes of the Tulahuen 2, INC-5, and NINOA strains. The compounds 3d and 4a showed better or similar trypanosomicidal activity than the reference drug nifurtimox. In addition, 3d and 4a also elicited better trypanosomicidal activity than nifurtimox against T. cruzi bloodstream trypomastigotes. On the other hand, 3b showed the highest selective indexes (SI values between 44 and 500, in the three T. cruzi strains). Finally, molecular docking studies suggested that these compounds could be potential trypanothione reductase inhibitors. Therefore, based on these new results, we validated that the aryloxy-naphthoquinone scaffold is essential to obtain more selective cytotoxic and trypanosomicidal compounds.

Chemical Constituents of Anacardium occidentale as Inhibitors of Trypanosoma cruzi Sirtuins.

Benznidazole and nifurtimox, the only drugs available for the treatment of Chagas disease, have limited efficacy and have been associated with severe adverse side effects. Thus, there is an urgent need to find new biotargets for the identification of novel bioactive compounds against the parasite and with low toxicity. Silent information regulator 2 (Sir2) enzymes, or sirtuins, have emerged as attractive targets for the development of novel antitrypanosomatid agents. In the present work, we evaluated the inhibitory effect of natural compounds isolated from cashew nut (Anacardium occidentale, L. Anacardiaceae) against the target enzymes TcSir2rp1 and TcSir2rp3 as well as the parasite. Two derivates of cardol (1, 2), cardanol (3, 4), and anacardic acid (5, 6) were investigated. The two anacardic acids (5, 6) inhibited both TcSir2rp1 and TcSir2rp3, while the cardol compound (2) inhibited only TcSir2rp1. The most potent sirtuin inhibitor active against the parasite was the cardol compound (2), with an EC50 value of 12.25 µM, similar to that of benznidazole. Additionally, compounds (1, 4), which were inactive against the sirtuin targets, presented anti-T. cruzi effects. In conclusion, our results showed the potential of Anacardium occidentale compounds for the development of potential sirtuin inhibitors and anti-Trypanosoma cruzi agents.

Identification of New Anti-Trypanosoma Cruzi Agents in Some Uruguayan Plants by NMR-Based Metabolomic Profiling

Identification of New Anti-Trypanosoma Cruzi Agents in Some Uruguayan Plants by NMR-Based Metabolomic Profiling

Palladium(II)/N,N-disubstituted-N′-acylthioureas complexes as anti-Mycobacterium tuberculosis and anti-Trypanosoma cruzi agents

The new complexes of Pd(II) with N,N-disubstituted-N′-acylthioureas:[(1) [Pd(dppf)(N,N-dimethyl-N′-benzoylthioureato-k2O,S)]PF6, (2) [Pd(dppf)(N,N-diethyl-N′-benzoylthioureato-k2O,S)]PF6, (3) [Pd(dppf)(N,N-dibuthyl-N′-benzoylthioureato-k2O,S)]PF6, (4) [Pd(dppf)(N,N-diphenyl-N′-benzoylthioureato-k2O,S)]PF6, (5) [Pd(dppf)(N,N-diethyl-N′-furoylthioureato-k2O,S)]PF6, (6) [Pd(dppf)(N,N-diphenyl-N′-furoylthioureato-k2O,S)]PF6, (7) [Pd(dppf)(N,N-dimethyl-N′- thiophenylthioureato-k2O,S)]PF6, and (8) [Pd(dppf)(N,N-diphenyl-N′-thiophenylthioureato-k2O,S)]PF6, were prepared and characterized by elemental analysis, and spectroscopic techniques. The structures of complexes (2), (3), (5), (6) and (8) had their structures determined by X-ray crystallography, confirming the coordination of the ligands with the metal through sulfur and oxygen atoms, forming distorted square-planar geometries. These complexes have shown antibacterial activity against anti-Mycobacterium tuberculosis H37Rv ATCC 27294. The complexes exhibited antiparasitic activity against Trypanosoma cruzi, while the metal-free thioureas did not. The results demonstrated that the compounds described here can be considered as promising anti-Mycobacterium tuberculosis and anti-T. cruzi agents, since in both cases their in vitro activity were better than reference drugs available for the treatment of both diseases.

Ferrocenyl and cyrhetrenyl azines containing a 5-nitroheterocyclic moiety: Synthesis, structural characterization, electrochemistry and evaluation as anti-Trypanosoma cruzi agents

The synthesis of unsymmetrical ferrocenyl and cyrhetrenyl azines [(η5-C5H4)-CR=N-N=CH-2-C4H2X-5-NO2]M (M=Re(CO)3, Fe(η5-C5H5); R = H, CH3, X = O, S) has led to the development of new derivatives of 5-nitroheterocycles as potential anti-trypanosomal agents. The structures of compounds have been confirmed using conventional spectroscopic techniques (FT-IR, 1H and 13C NMR), mass spectrometry, including single-crystal X-ray diffraction analysis of compounds 2NT and 4NT. Based on the chemical shifts of the iminic carbons (C6, C7) and the reduction potential of the nitro group (E1/2 NO2), an extensive π-conjugation of the azine bridge (-C(R)=N-N=CH-) was observed along with a correlation between the opposing electronic effects of the cyrhetrenyl and ferrocenyl fragments. It was established that the existence of an electron-withdrawing group (cyrhetrene) could facilitate the generation of radical species (RNO2 to RNO2−) through the azine bridge. The organometallic azines were evaluated for anti-trypanosomal activity in vitro against the epimastigote form of the Dm28c strain of T. cruzi, yielding IC50 values in the low micromolar range.

Discovery of potent nitrotriazole-based antitrypanosomal agents: In vitro and in vivo evaluation

3-Nitro-1H-1,2,4-triazole- and 2-nitro-1H-imidazole-based amides with an aryloxy-phenyl core were synthesized and evaluated as antitrypanosomal agents. All 3-nitrotriazole-based derivatives were extremely potent anti-Trypanosomacruzi agents at sub nM concentrations and exhibited a high degree of selectivity for the parasite. The 2-nitroimidazole analogs were only moderately active against T. cruzi amastigotes and exhibited low selectivity. Both types of compound were active against Leishmaniadonovani axenic amastigotes with excellent selectivity for the parasite, whereas three 2-nitroimidazole-based analogs were also moderately active against infected macrophages. However, no compound demonstrated selective activity against Trypanosoma bruceirhodesiense. The most potent in vitro anti-T. cruzi compounds were tested in an acute murine model and reduced the parasites to an undetectable level after five days of treatment at 13mg/kg/day. Such compounds are potential inhibitors of T. cruzi CYP51 and, being excellent substrates for the type I nitroreductase (NTR) which is specific to trypanosomatids, work as prodrugs and constitute a new generation of effective and more affordable antitrypanosomal agents.

Synthesis and biological evaluation of quinones derived from natural product komaroviquinone as anti-Trypanosoma cruzi agents.

Current chemotherapy drugs for Chagas' disease are insufficient due to their limited efficacy; however, anti-trypanosomal agents have recently shown promise. As such, synthetic intermediates of komaroviquinone were evaluated for anti-trypanosomal activity. Based on the results, a series of novel quinone derivatives were screened for anti-trypanosomal activity and mammalian cytotoxicity. Several quinone derivatives displayed higher antiprotozoal activity against Trypanosoma cruzi trypomastigotes than the reference drug benznidazole, without concomitant toxicity toward the host cell.

2-Pyridyl thiazoles as novel anti-Trypanosoma cruzi agents: Structural design, synthesis and pharmacological evaluation

The present work reports on the synthesis, anti-Trypanosoma cruzi activities and docking studies of a novel series of 2-(pyridin-2-yl)-1,3-thiazoles derived from 2-pyridine thiosemicarbazone. The majority of these compounds are potent cruzain inhibitors and showed excellent inhibition on the trypomastigote form of the parasite, and the resulting structure–activity relationships are discussed. Together, these data present a novel series of thiazolyl hydrazones with potential effects against Chagas disease and they could be important leads in continuing development against Chagas disease.

Ligand-based design, synthesis, and experimental evaluation of novel benzofuroxan derivatives as anti-Trypanosoma cruzi agents

A set of substituted-[N′-(benzofuroxan-5-yl)methylene]benzohydrazides (4a–t), previously designed and synthesized, was experimentally assayed against Trypanosoma cruzi, the etiological agent of Chagas' disease, one of the most neglected tropical diseases. Exploratory data analysis, Hansch approach and VolSurf formalism were applied to aid the ligand-based design of novel anti-T. cruzi agents. The best 2D-QSAR model showed suitable statistical measures [n = 18; s = 0.11; F = 42.19; R2 = 0.90 and Q2 = 0.77 (SDEP = 0.15)], and according to the optimum 3D-QSAR model [R2 = 0.98, Q2 = 0.93 (SDEP = 0.08)], three latent variables explained 62% of the total variance from original data. Steric and hydrophobic properties were pointed out as the key for biological activity. Based upon the findings, six novel benzofuroxan derivatives (4u–z) were designed, synthesized, and in vitro assayed to perform the QSAR external prediction. Then, the predictability for the both models, 2D-QSAR (Rpred2 = 0.91) and 3D-QSAR (Rpred2 = 0.77), was experimentally validated, and compound 4u was identified as the most active anti-T. cruzi hit (IC50 = 3.04 μM).

Synthesis and Biological Evaluation of New Sulfonamide Derivatives as Potential Anti-Trypanosoma cruzi Agents

Synthesis and Biological Evaluation of New Sulfonamide Derivatives as Potential Anti-Trypanosoma cruzi Agents

New imidazolidine derivatives as anti-Trypanosoma cruzi agents: structure–activity relationships

Imidazolidine derivatives are key components for the development of bioactive compounds for the treatment of many diseases, especially Chagas. In fact, others studies showed that the imidazolidine-2,4-dione has stood out by presenting a wide spectrum of pharmacological activities including anticonvulsants, antiarrhythmic, and antiparasitic. In the present study, we investigated the morphological alterations induced by imidazolidine derivates LPSF/NN-52 and LPSF/NN-100 on trypomastigotes forms of Trypanosoma cruzi through ultrastructural analysis by electron microscopy. Many concentrations were used to measure the antiparasitic propriety promoted by imidazolidine derivatives, and our study indicates that parasites treated with 13 μg mL(-1) of the imidazolidine derivates for 24 h revealed severe damage to the parasite's mitochondrial complex. Beyond that, also observed in treated parasites were the following: myelin bodies, enlargement of cytoplasm vacuole, fragmentation of endoplasmic reticulum, and some treated samples clearly showed signs of necrosis. To confirm the ultrastructural results, some assays were performed for knowledge cellular death induction promoted by imidazolidine derivates against immune spleen cells. The induction of the necrotic process through derivatives LPSF/NN-52 and LPSF/NN-100 showed similar results in relation to nifurtimox and benznidazole. In the last assays, it was demonstrated that NN-100 was efficient against epimastigotes and trypomastigotes forms and these results reinforce the mechanisms of action of both new imidazolidine derivatives against T. cruzi.

Bioactive-guided Identification of Labdane Diterpenoids from Aerial Parts of Aristeguietia glutinosa as anti-Trypanosoma cruzi agents

A bioactive-guided investigation of the hydro-ethanolic extract of aerial parts of Aristeguietia glutinosa Lam. resulted in the isolation of two diterpenoids, (+)-15-hydroxy-labd-7-en-17-al (1) and (+)-13,14,15,16-tetranor-labd-7-en-17,12-olide (2), as the anti-Trypanosoma cruzi active principles. The structures of 1 and 2 were determined by spectroscopic analysis. The hydro-ethanolic extract showed anti-T. cruzi activity (IC50 = 19.6 microg/mL) whereas the isolated compounds 1 and 2 were near to seven- and one and a half-fold (IC50 = 3.0 and 15.6 microg/mL), respectively more active than the original extract. Labdene 1, equipotent as the reference compound (Nifurtimox), displayed low hemolytic activity, low toxicity against murine macrophages, and absence of mutagenicity. These results support the vernacular medicinal use of this plant as an anti-T. cruzi agent.

Synthesis and Biological Evaluation of New Sulfonamide Derivatives as Potential Anti-Trypanosoma cruzi Agents

Chagas disease continues to be one of the main parasitic diseases in Latin America. Despite the fact that it was discovered more than 100 years ago, no suitable pharmacologic treatment is available. We report the synthesis of new sulfonamidoquinoline and sulfonamides derivatives that were evaluated in vitro against two strains of Trypanosoma cruzi (NINOA and INC-5). Structure-activity relationship analysis indicated that small aromatic and large aromatic substituents on 4-aminoquinaldine increased trypanocidal activity on INC-5 and NINOA strains, respectively. Additionally, results show the importance of the sulfonamide group as a scaffold for the development of new anti-T. cruzi agents. Seven sulfonamide derivatives showed better lytic activity than nifurtimox and beznidazole against both strains of T. cruzi. N- (biphenyl-4-yl-sulfonyl)-nicotinamide (P-012) was established as the leader of the series for the development of more effective agents.

Synthesis and biological evaluation of some novel 1-indanone thiazolylhydrazone derivatives as anti-Trypanosoma cruzi agents

A series of novel 4-arylthiazolylhydrazones (TZHs) derived from 1-indanones were synthesized in good yields (66–92%) in a simple procedure using microwave irradiation and then characterized by spectroscopy studies. The compounds were evaluated for their in vitro anti-Trypanosoma cruzi activity against the epimastigote, trypomastigote and amastigote forms of the parasite. Most TZHs displayed excellent activity, and were more potent and selective than the reference drug Benznidazole, used in the current chemotherapy. Analysis of the free sterols from parasite incubated with the compounds showed that inhibition of ergosterol biosynthesis is a possible target for the action of these new TZHs. In particular, TZH 9 emerged as a promising antichagasic compound to be evaluated in animal models.

Thiosemicarbazones derived from 1-indanones as new anti-Trypanosoma cruzi agents

In the present work, we synthesized a series of thiosemicarbazones derived from 1-indanones with good anti-Trypanosoma cruzi activity. Most of them displayed remarkable trypanosomicidal activity. All the compounds showed nonspecific cytotoxicity on human erythrocytes. The ability of the new compounds to inhibit cruzipain, the major cysteine protease of T. cruzi, was also explored. Thiosemicarbazones 12 and 24 inhibited this enzyme at the dose assayed. This interaction was also studied in terms of molecular docking.

A class of sterol 14-demethylase inhibitors as anti-Trypanosoma cruzi agents.

Chronic infection with the protozoan parasite Trypanosoma cruzi is a major cause of morbidity and mortality in Latin America. Drug treatments for the associated illness, Chagas disease, are toxic and frequently unsuccessful. In a screening effort against the drug target protein farnesyltransferase, we identified a series of disubstituted imidazoles with highly potent anti-T. cruzi activity that apparently acted through a mechanism independent of protein farnesylation. Metabolic labeling studies of T. cruzi suggested that sterol biosynthesis was inhibited. Combined GC/MS analysis confirmed depletion of cellular sterols and suggested that the site of action was sterol 14-demethylase, a cytochrome P450 enzyme. Spectral studies with recombinant T. cruzi sterol 14-demethylase demonstrated that the compounds bind directly to this enzyme. Two of the compounds were well absorbed when given orally to mice, gave sustained plasma levels, and were well tolerated. The compounds were administered orally to mice with acute T. cruzi infection and caused dramatic decrease in parasitemia and led to 100% survival. These disubstituted imidazole compounds can be prepared by a relatively short synthetic route and represent a structural class with potent anti-T. cruzi activity.