In vitro and in vivo trypanocidal activity of some benzimidazole derivatives against two strains of Trypanosoma cruzi

Ninoa T. cruzi Strain Modifies the Expression of microRNAs in Cardiac Tissue and Plasma During Chagas Disease Infection

Background: Chronic chagasic cardiomyopathy is the most severe clinical manifestation of Chagas disease, which affects approximately seven million people worldwide. Latin American countries bear the highest burden, with the greatest morbidity and mortality rates. Currently, diagnostic methods do not provide information on the risk of progression to severe stages of the disease. Recently, microRNAs (miRNAs) have been proposed as promising tools for monitoring the progression of Chagas disease. This study aimed to analyze the expression profiles of the miRNAs miR-1, miR-16, miR-208, and miR-208b in cardiac tissue, plasma, and plasma extracellular vesicles from Ninoa TcI-infected mice during the acute and indeterminate phases of Chagas disease. Methods: The cardiac-specific miRNAs and miR-16 levels were examined in all samples using RT-qPCR. Additionally, pathway analysis was performed to investigate the impact of potential miRNA target genes across various databases. Results: Elevated miR-208b expression was observed in cardiac tissue and plasma during the acute phase. Bioinformatic analysis identified three pathways implicated in disease progression: phosphatidylinositol 3-kinase signaling, Fc gamma receptor-mediated phagocytosis, and leukocyte transendothelial migration, as well as cholinergic synapse pathways. Conclusions: MiR-208b was upregulated during the acute phase and downregulated in the indeterminate phase, suggesting it may play a crucial role in disease progression.

Anti-Trypanosoma cruzi activity of Coptis rhizome extract and its constituents

BACKGROUND

Current therapeutic agents, including nifurtimox and benznidazole, are not sufficiently effective in the chronic phase of Trypanosoma cruzi infection and are accompanied by various side effects. In this study, 120 kinds of extracts from medicinal herbs used for Kampo formulations and 94 kinds of compounds isolated from medicinal herbs for Kampo formulations were screened for anti-T. cruzi activity in vitro and in vivo.

METHODS

As an experimental method, a recombinant protozoan cloned strain expressing luciferase, namely Luc2-Tulahuen, was used in the experiments. The in vitro anti-T. cruzi activity on epimastigote, trypomastigote, and amastigote forms was assessed by measuring luminescence intensity after treatment with the Kampo extracts or compounds. In addition, the cytotoxicity of compounds was tested using mouse and human feeder cell lines. The in vivo anti-T. cruzi activity was measured by a murine acute infection model using intraperitoneal injection of trypomastigotes followed by live bioluminescence imaging.

RESULTS

As a result, three protoberberine-type alkaloids, namely coptisine chloride, dehydrocorydaline nitrate, and palmatine chloride, showed strong anti-T. cruzi activities with low cytotoxicity. The IC₅₀ values of these compounds differed depending on the side chain, and the most effective compound, coptisine chloride, showed a significant effect in the acute infection model.

CONCLUSIONS

For these reasons, coptisine chloride is a hit compound that can be a potential candidate for anti-Chagas disease drugs. In addition, it was expected that there would be room for further improvement by modifying the side chains of the basic skeleton.

A Data-Driven Approach to Construct a Molecular Map of Trypanosoma cruzi to Identify Drugs and Vaccine Targets

Chagas disease (CD) is endemic in large parts of Central and South America, as well as in Texas and the southern regions of the United States. Successful parasites, such as the causative agent of CD, Trypanosoma cruzi have adapted to specific hosts during their phylogenesis. In this work, we have assembled an interactive network of the complex relations that occur between molecules within T. cruzi. An expert curation strategy was combined with a text-mining approach to screen 10,234 full-length research articles and over 200,000 abstracts relevant to T. cruzi. We obtained a scale-free network consisting of 1055 nodes and 874 edges, and composed of 838 proteins, 43 genes, 20 complexes, 9 RNAs, 36 simple molecules, 81 phenotypes, and 37 known pharmaceuticals. Further, we deployed an automated docking pipeline to conduct large-scale docking studies involving several thousand drugs and potential targets to identify network-based binding propensities. These experiments have revealed that the existing FDA-approved drugs benznidazole (Bz) and nifurtimox (Nf) show comparatively high binding energies to the T. cruzi network proteins (e.g., PIF1 helicase-like protein, trans-sialidase), when compared with control datasets consisting of proteins from other pathogens. We envisage this work to be of value to those interested in finding new vaccines for CD, as well as drugs against the T. cruzi parasite.

A comprehensive phytochemical and pharmacological review on sesquiterpenes from the genus Ambrosia

Sesquiterpenes are bitter secondary metabolites characteristic to the genus Ambrosia (Asteraceae) and constitute one of the most diverse classes of terpenoids. These compounds exhibit broad-spectrum bioactivities, such as antiproliferative, cytotoxic, antimicrobial, anti-inflammatory, molluscicidal, schistomicidal, larvicidal, and antiprotozoal activities. This review compiles and discusses the chemistry and pharmacology of sesquiterpenes of the Ambrosia species covering the period between 1950 and 2021. The review identified 158 sesquiterpenes previously isolated from 23 different Ambrosia species collected from across the American, African, and Asian continents. These compounds have guaiane, pseudoguaiane, seco-pseudoguaiane, daucane, germacrane, eudesmane, oplopane, clavane, and aromadendrane carbon skeletons. Most sesquiterpene compounds predominantly harbor the pseudoguaiane skeleton, whereas the eudesmanes have the most varied substituents. Antiproliferative and antiprotozoal activities are the most promising bioactivities of sesquiterpenes in Ambrosia and could lead to new pathways toward drug discovery.

In vitro, ex vivo and in vivo short-term screening of DHEA nitrate derivatives activity over Trypanosoma cruzi Ninoa and TH strains from Oaxaca State, México

Chagas disease is a health problem that affects millions of persons, currently Nifurtimox (Nfx) and Benznidazole (Bz) are the unique drugs to treat it. However, these drugs produce adverse effects and high toxicity, which has motivated the search for new candidate drugs. Based on reports about the extensive biological activity of steroidal nitrate esters, in this study three nitrate esters steroids (1b, 2b and 4b) were synthetized and characterized from Dehydroepiandrosterone (DHEA, 1a), 19-hydroxy-DHEA (2a), and Androst-5-en-3β,17β-diol (4a), respectively. In addition, compounds 3a and 3b were obtained by introducing an α-ethynyl and a β-hydroxyl groups at position 17 of 2b and further nitration of the hydroxyl group. The trypanocidal activity of these steroids was evaluated in vitro against the epimastigote stage of two T. cruzi strains, Ninoa and TH, and their cytotoxicity over J774.2 macrophage cell line was assayed. Compounds 3a, 3b, and 4a shown higher trypanocidal activity than Bz and Nfx against epimastigotes of Ninoa strain, whereas DHEA (1a) and its nitrate derivative 1b showed higher activity than the reference drugs against the TH strain epimastigote. None of the compounds showed activity in the ex vivo assays against the blood trypomastigote of both strains. Interestingly, the selectivity index of Androst-5-en-3β,17β-diol 4a was almost twice the value of Nfx and 50 times more than Bz, against Ninoa and TH strains, respectively. Therefore, compound 4a could represent a valuable starting point toward the optimization of steroid derivatives as trypanocidal agents.

Circulating miR-146a as a possible candidate biomarker in the indeterminate phase of Chagas disease

BACKGROUND

Chagas disease is considered important and presents intense inflammatory and fibrotic processes induced by the perpetuation of the parasite in the affected tissues and organs. Therefore, it is necessary to inquire about the host defense and attack mechanisms to have a more detailed knowledge about Chagas disease. MicroRNAs are found in blood, tissues and extracellular vesicles. These small regulators of gene expression are involved in physiological and pathological processes in both mammals and parasites. Several microRNAs have deregulated expression in chagasic heart disease, although little is known about their extracellular expression. Our main objective was to evaluate the involvement of miR-21, miR-146a and miR-155 in several samples from mice infected with the TcI Ninoa strain from the acute and indeterminate phases. We also explored a potential functional association of the selected microRNAs using STRING software. This software identified 23 pathways associated with Trypanosoma cruzi infection. In addition, eleven genes were identified through bioinformatics analysis, and we found that SMAD family member 5 was downregulated in both phases. This gene serves as a mediator in the TGF-β signaling pathway. Thus, forty female mice of the CD1 strain were distributed into 4 groups and the expression levels of miR-21, miR-146a and miR-155 were measured in samples of heart tissue, total plasma and plasma extracellular vesicles by quantitative real-time polymerase chain reaction.

RESULTS

Overexpression of miR-21, miR-146a and miR-155 was observed in heart and plasma in both phases. Moreover, in extracellular vesicles miR-21 and miR-146a were also overexpressed in the acute phase, whereas in the indeterminate chronic phase we found only miR-146a up-regulated.

CONCLUSIONS

The expression of inflammatory microRNAs miR-21, miR-146a and miR-155 were up-regulated in each of the samples from acutely and chronically infected mice. The relevant finding was that miR-146a was up-regulated in each sample in both phases; therefore, this miRNA could be a possible candidate biomarker in Chagas disease.

Phenylbenzothiazole derivatives: effects against a Trypanosoma cruzi infection and toxicological profiles

Current treatments for Chagas disease have a limited impact during the chronic stage and trigger severe side effects. Treatments target Trypanosoma cruzi, the etiological agent of the disease. The aims of this study were to evaluate the trypanocidal activity of four 2-phenylbenzothiazole derivatives (BZT1-4) in vitro by using the infectious and non-infectious forms of T. cruzi (trypomastigotes and epimastigotes, respectively) and to test the most promising compound (BZT4) in vivo in mice. Additionally, the toxicological profile and possible neuronal damage were examined. In relation to trypomastigotes, BZT4 was more selective and effective than the reference drug (benznidazole) during this infective stage, apparently due to the synergistic action of the CF₃ and COOH substituents in the molecule. During the first few hours post-administration of BZT4, parasitemia decreased by 40% in an in vivo model of short-term treatment, but parasite levels later returned to the basal state. In the long-term assessment, the compound did not produce a significant antiparasitic effect, only attaining a 30% reduction in parasitemia by day 20 with the dose of 16 mg/kg. The toxicity test was based on repeated dosing of BZT4 (administered orally) during 21 days, which did not cause liver damage. However, the compound altered the concentration of proteins and the proteinic profile of neuronal cells in vitro, perhaps leading to an effect on the central nervous system. Further research on the low trypanocidal activity in vivo compared to the better in vitro effect could possibly facilitate molecular redesign to improve trypanocidal activity.

Imidazoles and Oxazoles from Lapachones and Phenanthrene-9,10-dione: A Journey through their Synthesis, Biological Studies, and Optical Applications

Diverse structural frameworks are found in natural compounds and are well known for their chemical and biological properties; such compounds include the imidazoles and oxazoles. Researchers worldwide are continually working on the development of methods for synthesizing new molecules bearing these basic moiety and evaluating their properties and applications. To expand the knowledge related to azoles, this review summarizes important examples of imidazole and oxazole derivatives from 1,2-dicarbonyl compounds, such as lapachones and phenanthrene-9,10-diones, not only regarding their synthesis and biological applications but also their photophysical properties and uses. The data concerning the latter are particularly scarce in the literature, which leads to underestimation of the potential applications that can be envisaged for these compounds.

The Role of Nitro (NO2-), Chloro (Cl), and Fluoro (F) Substitution in the Design of Antileishmanial and Antichagasic Compounds

Neglected tropical diseases (NTDs) are responsible for over 500,000 deaths annually and are characterized by multiple disabilities. Leishmaniasis and Chagas diseases are among the most severe NTDs, and are caused by the Leishmania sp and Trypanosoma cruzi, respectively. Glucantime, pentamidine, and miltefosine are commonly used to treat leishmaniasis, whereas nifurtimox, benznidazole are current treatments for Chagas disease. However, these treatments are associated with drug resistance and severe side effects. Hence, the development of synthetic products, especially those containing N0₂, F, or Cl, are known to improve biological activity. The present work summarizes the information on the antileishmanial and antitrypanosomal activity of nitro-, chloro-, and fluorosynthetic derivatives. Scientific publications referring to halogenated derivatives in relation to antileishmanial and antitrypanosomal activities were hand-searched in databases such as SciFinder, Wiley, Science Direct, PubMed, ACS, Springer, Scielo, and so on. According to the literature information, more than 90 compounds were predicted as lead molecules with reference to their IC₅₀/EC₅₀ values in in vitro studies. It is worth mentioning that only active compounds with known cytotoxic effects against mammalian cells were considered in the present study. The observed activity was attributed to the presence of nitro-, fluoro-, and chloro-groups in the compound backbone. All in all, nitro and halogenated derivatives are active antileishmanial and antitrypanosomal compounds and can serve as the baseline for the development of new drugs against leishmaniasis and Chagas disease. However, efforts in in vitro and in vivo toxicity studies of the active synthetic compounds is still needed. Pharmacokinetic studies and the mechanism of action of the promising compounds need to be explored. The use of new catalysts and chemical transformation can afford unexplored halogenated compounds with improved antileishmanial and antitrypanosomal activity.

The role of imidazole and benzimidazole heterocycles in Chagas disease: A review

The haemoflagellate protozoan Trypanosoma cruzi (T. cruzi) is the causative agent of Chagas disease (CD), a potentially life-threatening disease. Little by little, remarkable progress has been achieved against CD, although it is still not enough. In the absence of effective chemotherapy, many research groups, organizations and pharmaceutical companies have focused their efforts on the search for compounds that could become viable drugs against CD. Within the wide variety of reported derivatives, this review summarizes and provides a global vision of the situation of those compounds that include broadly studied heterocycles in their structures due to their applications in medicinal chemistry: imidazole and benzimidazole rings. Therefore, the intention of this work is to present a compilation, as much as possible, of all the reported information, regarding these imidazole and benzimidazole derivatives against T. cruzi, as a starting point for future researchers in this field.

In silico tools to study molecular targets of neglected diseases: inhibition of TcSir2rp3, an epigenetic enzyme of Trypanosoma cruzi

There is a growing interest to study and address neglected tropical diseases (NTD). To this end, in silico methods can serve as the bridge that connects academy and industry, encouraging the development of future treatments against these diseases. This chapter discusses current challenges in the development of new therapies, available computational methods and successful cases in computer-aided design with particular focus on human trypanosomiasis. Novel targets are also discussed. As a case study, we identify amentoflavone as a potential inhibitor of TcSir2rp3 (sirtuine) from Trypanosoma cruzi (20.03 μM) with a workflow that integrates chemoinformatic approaches, molecular modeling, and theoretical affinity calculations, as well as in vitro assays.

Partial inhibition of the tricarboxylic acid cycle in Taenia crassiceps cysticerci after the in vitro exposure to a benzimidazole derivative (RCB15)

The benzimidazole derivative, 6-chloro-5-(2,3-dichlorophenoxy)-2-(trifluoromethyl)-1H-benzimidazole (RCB15), has a similar mode of action and efficacy as albendazole, a commonly used anthelminthic drugs. The aim of this study was to evaluate its influence on the tricarboxylic acid cycle in Taenia crassiceps cysticerci. The parasites were cultured in supplemented RPMI medium containing albendazole sulfoxide (ABZSO) or RCB15, for 24 h. Then, frozen in liquid nitrogen for organic metabolites extraction. Samples were analyzed by high performance liquid chromatography and organic acids of the tricarboxylic acid cycle were detected. It was possible to observe changes in the concentrations of all acids involved in this metabolic pathway, with the exception of α-ketoglutarate, which was not detected in the control group neither in most of the treated groups. It indicates that the parasite presented a partial inhibition of the tricarboxylic acid cycle. The significant increase in the concentration of citrate, oxaloacetate and succinate in the RCB15 treated groups may indicate an activation of the fumarate reductase pathway, leading to metabolic distress. Therefore RCB15 may be considered an alternative for the treatment of tissue parasitic diseases, since it induced changes in the main metabolic pathway of the parasite.

Pharmacological significance of heterocyclic 1H-benzimidazole scaffolds: a review

Heterocyclic compounds are inevitable in a numerous part of life sciences. These molecules perform various noteworthy functions in nature, medication and innovation. Nitrogen-containing heterocycles exceptionally azoles family are the matter of interest in synthesis attributable to the way that they happen pervasively in pharmacologically dynamic natural products, multipurpose arranged useful materials also profoundly powerful pharmaceuticals and agrochemicals. Benzimidazole moiety is the key building block for several heterocyclic scaffolds that play central role in the biologically functioning of essential molecules. They are considered as promising class of bioactive scaffolds encompassing diverse varieties of activities like antiprotozoal, antihelminthic, antimalarial, antiviral, anti-inflammatory, antimicrobial, anti-mycobacterial and antiparasitic. Therefore in the present review we tried to compile the various pharmacological activities of different derivatives of heterocyclic benzimidazole moiety.

Facile Synthesis of a Series of Non-Symmetric Thioethers Including a Benzothiazole Moiety and Their Use as Efficient In Vitro anti-Trypanosoma cruzi Agents

A series of 2-benzylsulfanyl benzothiazole (BTA) derivatives were synthesized and fully characterized and in vitro tested against two strains of T. cruzi (NINOA and INC-5), exhibiting good activities at low concentrations.

Coumarins isolated from Calophyllum brasiliense produce ultrastructural alterations and affect in vitro infectivity of Trypanosoma cruzi

BACKGROUND

The current drugs for Chagas Disease caused by the protozoan Trypanosoma cruzi have limited therapeutic potential and are associated with serious side effects. Natural products can aid to develop new chemotherapeutic agents. Several natural coumarins, especially Mammea A/BA, have shown significant activity against T. cruzi and low toxicity on human lymphocytes, but its effectivity on a wide range of strains need to be tested, as well as to deepen in their mode of action and safety.

HYPOTHESIS/PURPOSE

To discern the effects and explore the action mechanisms of mammea A/BA and a mixture of mammea coumarins isolated from Calophyllum brasiliense on Mexican strains of T. cruzi belonging to different genotypes and compare its effectivity with the drug benznidazole.

STUDY DESIGN

We evaluated the trypanocidal activity in vitro of mammea A/BA (93.6%), and a mixture of coumarins, mammea A/BA + A/BB + A/BD (86:10:1%) on Mexican T. cruzi strains belonging to different genotypes Ninoa, Querétaro (TcI) and Ver6 (TcVI).

MATERIAL AND METHODS

Mammea A/BA and the mixture of coumarins, were isolated from Calophyllum brasiliense, identified by proton NMR and purity determined by HPLC. The in vitro trypanocidal activity was evaluated on mobility, growth recovery, morphology and infectivity of T. cruzi. The cytotoxicity on mammalian cells was compared with benznidazole. The ultrastructure of the treated epimastigotes was analyzed by transmission electron microscopy (TEM).

RESULTS

Mammea A/BA and the mixture of coumarins showed high trypanocidal activity, affecting the mobility, growth recovery, morphology, ultrastructure of epimastigotes, and drastically reduce trypomastigotes infectivity on Vero cells. These substances were four times more potent than benznidazole and showed low cytotoxicity and high selectivity index. The TEM showed severe alterations on the plasmatic membrane, nuclear envelope, as well as, mitochondrial swelling, that leads to the death of parasites.

CONCLUSION

Mammea A/BA (93.6%) and a mixture of mammea A/BA + A/BB and A/BD (86: 10: 1%) isolated from the tropical tree C. brasiliense showed higher trypanocidal activity than the current drug benznidazole on three Mexican strains of T. cruzi. These compounds induced severe physiological and morphological alterations. These results suggest their possible use in preclinical studies.

Tailoring microstructural, drug release properties, and antichagasic efficacy of biocompatible oil-in-water benznidazol-loaded nanoemulsions

This study explored the transition of lamellar-type liquid crystal (LLC) to biocompatible oil-in-water nanoemulsions able to modify benznidazole (BNZ) release and target the drug to cells infected with the T. cruzi parasite. Three cosolvents (2methylpyrrolidone [NMP], polyethylene glycol [POL], and propylene glycol [PRO] were tested to induce the transition of anisotropic LLC systems to isotropic nanoemulsions. Mixtures of soy phosphatidylcholine with sodium oleate stabilized the dispersions of medium chain triglyceride in water. Rheological measurements, polarized microscopy, and small angle X-ray scattering demonstrated that there is a phase transition from LLC to desired nanoemulsions. These small and narrow droplet-sized nanocarriers exhibited some advantages and promising features, such as the enhanced BNZ aqueous solubility and slow drug release rate. In vitro cell biocompatibility of formulations was assessed in the Vero E6 and SiHa cell lines. Drug-loaded nanoemulsions inhibited the epimastigote growth of the T. cruzi parasite (IC50 0.208 ± 0.052 μg mL^-1) and reduced its infective life form trypomastigote (IC50 0.392 ± 0.107 μg mL^-1). The oil-in-water nanoemulsions were demonstrated as promising biocompatible liquid drug delivery systems capable of improving the BNZ trypanocidal activity for the treatment of Chagas disease.

In vitro activity of new N-benzyl-1H-benzimidazol-2-amine derivatives against cutaneous, mucocutaneous and visceral Leishmania species

The identification of specific therapeutic targets and the development of new drugs against leishmaniasis are urgently needed, since chemotherapy currently available for its treatment has several problems including many adverse side effects. In an effort to develop new antileishmanial drugs, in the present study a series of 28 N-benzyl-1H-benzimidazol-2-amine derivatives was synthesized and evaluated in vitro against Leishmania mexicana promastigotes. Compounds 7 and 8 with the highest antileishmanial activity (micromolar) and lower cytotoxicity than miltefosine and amphotericin B were selected to evaluate their activity against L. braziliensis 9and L. donovani, species causative of mucocutaneous and visceral leishmaniasis, respectively. Compound 7 showed significantly higher activity against L. braziliensis promastigotes than compound 8 and slightly lower than miltefosine. Compounds 7 and 8 had IC₅₀ values in the micromolar range against the amastigote of L. mexicana and L. braziliensis. However, both compounds did not show better activity against L. donovani than miltefosine. Compound 8 showed the highest SI against both parasite stages of L. mexicana. In addition, compound 8 inhibited 68.27% the activity of recombinant L. mexicana arginase (LmARG), a therapeutic target for the treatment of leishmaniasis. Docking studies were also performed in order to establish the possible mechanism of action by which this compound exerts its inhibitory effect. Compound 8 shows promising potential for the development of more potent antileishmanial benzimidazole derivatives.

Imaging mass spectrometry and MS/MS molecular networking reveals chemical interactions among cuticular bacteria and pathogenic fungi associated with fungus-growing ants

The fungus-growing ant-microbe symbiosis is an ideal system to study chemistry-based microbial interactions due to the wealth of microbial interactions described, and the lack of information on the molecules involved therein. In this study, we employed a combination of MALDI imaging mass spectrometry (MALDI-IMS) and MS/MS molecular networking to study chemistry-based microbial interactions in this system. MALDI IMS was used to visualize the distribution of antimicrobials at the inhibition zone between bacteria associated to the ant Acromyrmex echinatior and the fungal pathogen Escovopsis sp. MS/MS molecular networking was used for the dereplication of compounds found at the inhibition zones. We identified the antibiotics actinomycins D, X2 and X_0β, produced by the bacterium Streptomyces CBR38; and the macrolides elaiophylin, efomycin A and efomycin G, produced by the bacterium Streptomyces CBR53.These metabolites were found at the inhibition zones using MALDI IMS and were identified using MS/MS molecular networking. Additionally, three shearinines D, F, and J produced by the fungal pathogen Escovopsis TZ49 were detected. This is the first report of elaiophylins, actinomycin X_0β and shearinines in the fungus-growing ant symbiotic system. These results suggest a secondary prophylactic use of these antibiotics by A. echinatior because of their permanent production by the bacteria.

In vitro and in vivo assessment of newer quinoxaline-oxadiazole hybrids as antimicrobial and antiprotozoal agents

A new series of N-(substituted-phenyl)-2-[5-(quinoxalin-2-yloxymethyl)-[1,3,4] oxadiazol-2-ylsulfanyl]-acetamides (5a-o) was designed and synthesised from the parent compound 2-hydroxy quinoxaline (1) through a multistep reaction sequence and was characterised by spectral and elemental analyses. All of the compounds synthesised were evaluated for their antimicrobial and antiprotozoal activities. The results revealed that quinoxaline-based 1,3,4-oxadiazoles displayed promising antibacterial, antifungal and anti-Trypanosoma cruzi activities compared with reference drugs, particularly the lead compound 5l in a short-term in vivo model in T. cruzi.

Repositioning FDA Drugs as Potential Cruzain Inhibitors from Trypanosoma cruzi: Virtual Screening, In Vitro and In Vivo Studies

Chagas disease (CD) is a neglected disease caused by the parasite Trypanosoma cruzi, which affects underdeveloped countries. The current drugs of choice are nifurtimox and benznidazole, but both have severe adverse effects and less effectivity in chronic infections; therefore, the need to discover new drugs is essential. A computer-guided drug repositioning method was applied to identify potential FDA drugs (approved and withdrawn) as cruzain (Cz) inhibitors and trypanocidal effects were confirmed by in vitro and in vivo studies. 3180 FDA drugs were virtually screened using a structure-based approach. From a first molecular docking analysis, a set of 33 compounds with the best binding energies were selected. Subsequent consensus affinity binding, ligand amino acid contact clustering analysis, and ranked position were used to choose four known pharmacological compounds to be tested in vitro. Mouse blood samples infected with trypomastigotes from INC-5 and NINOA strains were used to test the trypanocidal effect of four selected compounds. Among these drugs, one fibrate antilipemic (etofyllin clofibrate) and three β-lactam antibiotics (piperacillin, cefoperazone, and flucloxacillin) showed better trypanocidal effects (LC₅₀ range 15.8-26.1 μg/mL) in comparison with benznidazole and nifurtimox (LC₅₀ range 33.1-46.7 μg/mL). A short-term in vivo evaluation of these compounds showed a reduction of parasitemia in infected mice (range 90-60%) at 6 h, but this was low compared to benznidazole (50%). This work suggests that four known FDA drugs could be used to design and obtain new trypanocidal agents.

Synthesis and biological evaluation of 2-methyl-1H-benzimidazole-5-carbohydrazides derivatives as modifiers of redox homeostasis of Trypanosoma cruzi

Twelve novel benzimidazole derivatives were synthesized and their in vitro activities against epimastigotes of Trypanosoma cruzi were evaluated. Two derivatives (6 and 7), which have 4-hydroxy-3-methoxyphenyl moiety in their structures, proved to be the most active in inhibiting the parasite growth. Compound 6 showed a trypanocidal activity higher than benznidazole (IC₅₀=5µM and 7.5µM, respectively) and less than nifurtimox (IC₅₀=3.6µM). In addition, the ability of 6 and 7 to modify the redox homeostasis in T cruzi epimastigote was studied; cysteine and glutathione increased in parasites exposed to both compounds, whereas trypanothione only increased with 7 treatment. These results suggest that the decrease in viability of T. cruzi may be attributed to the change in cellular redox balance caused by compound 6 or 7. Furthermore, compounds 6 and 7 showed CC₅₀ values of 160.64 and 160.66µM when tested in mouse macrophage cell line J774 and selectivity indexes (macrophage/parasite) of 32 and 20.1, respectively.

Trypanocidal Activity of Quinoxaline 1,4 Di-N-oxide Derivatives as Trypanothione Reductase Inhibitors

Chagas disease or American trypanosomiasis is a worldwide public health problem. In this work, we evaluated 26 new propyl and isopropyl quinoxaline-7-carboxylate 1,4-di-N-oxide derivatives as potential trypanocidal agents. Additionally, molecular docking and enzymatic assays on trypanothione reductase (TR) were performed to provide a basis for their potential mechanism of action. Seven compounds showed better trypanocidal activity on epimastigotes than the reference drugs, and only four displayed activity on trypomastigotes; T-085 was the lead compound with an IC₅₀ = 59.9 and 73.02 µM on NINOA and INC-5 strain, respectively. An in silico analysis proposed compound T-085 as a potential TR inhibitor with better affinity than the natural substrate. Enzymatic analysis revealed that T-085 inhibits parasite TR non-competitively. Compound T-085 carries a carbonyl, a CF₃, and an isopropyl carboxylate group at 2-, 3- and 7-position, respectively. These results suggest the chemical structure of this compound as a good starting point for the design and synthesis of novel trypanocidal derivatives with higher TR inhibitory potency and lower toxicity.

In vivo and in vitro auranofin activity against Trypanosoma cruzi: Possible new uses for an old drug

Chagas disease, Sleeping Sickness, Nagana and Leishmaniasis are serious infections caused by protozoa of the order Kinetoplastidae. They were described over a century ago by seminal work of different physician-researchers and, despite the initial discoveries, few drugs have been made available for the treatment of these infections. The drugs available present serious efficacy and toxicity problems. Moreover, the emergence of resistant strains has rendered the development of novel chemotherapeutic strategies a priority. Auranofin is currently in use to treat rheumatoid arthritis in humans. Previous reports showed that this compound presents activity against Trypanosoma brucei and Leishmania cells. In Trypanosoma cruzi cells, auranofin resulted in a more potent compound than benznidazole in vitro when tested in different DTUs. In vivo experiments, although not decreasing T. cruzi parasitemia, decreases host mortality. Therefore, we propose auranofin as a potential alternative for a new chemotherapy in Chagas disease with the added advantage of already being approved for use in humans.

JVG9, a benzimidazole derivative, alters the surface and cytoskeleton of Trypanosoma cruzi bloodstream trypomastigotes

Trypanosoma cruzi has a particular cytoskeleton that consists of a subpellicular network of microtubules and actin microfilaments. Therefore, it is an excellent target for the development of new anti-parasitic drugs. Benzimidazole 2-carbamates, a class of well-known broad-spectrum anthelmintics, have been shown to inhibit the in vitro growth of many protozoa. Therefore, to find efficient anti-trypanosomal (trypanocidal) drugs, our group has designed and synthesised several benzimidazole derivatives. One, named JVG9 (5-chloro-1H-benzimidazole-2-thiol), has been found to be effective against T. cruzi bloodstream trypomastigotes under both in vitro and in vivo conditions. Here, we present the in vitro effects observed by laser scanning confocal and scanning electron microscopy on T. cruzi trypomastigotes. Changes in the surface and the distribution of the cytoskeletal proteins are consistent with the hypothesis that the trypanocidal activity of JVG9 involves the cytoskeleton as a target.

Anti-Trypanosoma cruzi and anti-leishmanial activity by quinoxaline-7-carboxylate 1,4-di-N-oxide derivatives

In this work, a novel series of ethyl and methyl quinoxaline-7-carboxylate 1,4-di-N-oxide derivatives were evaluated in vitro on Trypanosoma cruzi trypomastigotes and Leishmania mexicana promastigotes, and cytotoxicity activity in murine macrophages was tested. In silico molecular docking simulations of trypanothione reductase were also done. Three compounds of 33 quinoxaline-7-carboxylate 1,4-di-N-oxide derivatives showed better anti-T. cruzi activity than nifurtimox and beznidazole; two compounds had better anti-leishmanial activity that amphotericin-B, and two compounds showed better activity against both parasites than reference drugs. Compounds M2, M7, M8 and E5, showed low cytotoxic activity on the host cell. The in silico studies suggest that compound M2 is a potential trypanothione reductase inhibitor.

Activities of psilostachyin A and cynaropicrin against Trypanosoma cruzi in vitro and in vivo

In vitro and in vivo activities against Trypanosoma cruzi were evaluated for two sesquiterpene lactones: psilostachyin A and cynaropicrin. Cynaropicrin had previously been shown to potently inhibit African trypanosomes in vivo, and psilostachyin A had been reported to show in vivo effects against T. cruzi, albeit in another test design. In vitro data showed that cynaropicrin was more effective than psilostachyin A. Ultrastructural alterations induced by cynaropicrin included shedding events, detachment of large portions of the plasma membrane, and vesicular bodies and large vacuoles containing membranous structures, suggestive of parasite autophagy. Acute toxicity studies showed that one of two mice died at a cynaropicrin dose of 400 mg/kg of body weight given intraperitoneally (i.p.). Although no major plasma biochemical alterations could be detected, histopathology demonstrated that the liver was the most affected organ in cynaropicrin-treated animals. Although cynaropicrin was as effective as benznidazole against trypomastigotes in vitro, the treatment (once or twice a day) of T. cruzi-infected mice (up to 50 mg/kg/day cynaropicrin) did not suppress parasitemia or protect against mortality induced by the Y and Colombiana strains. Psilostachyin A (0.5 to 50 mg/kg/day given once a day) was not effective in the acute model of T. cruzi infection (Y strain), reaching 100% animal mortality. Our data demonstrate that although it is very promising against African trypanosomes, cynaropicrin does not show efficacy compared to benznidazole in acute mouse models of T. cruzi infection.

Antitrypanosomal alkaloids from the marine bacterium Bacillus pumilus

Fractionation of the ethyl acetate extract of the marine bacterium Bacillus pumilus isolated from the black coral Antipathes sp. led to the isolation of five compounds: cyclo-(L-Leu-L-Pro) (1), 3-hydroxyacetylindole (2), N-acetyl-β-oxotryptamine (3), cyclo-(L-Phe-L-Pro) (4), and 3-formylindole (5). The structures of compounds 1−5 were established by spectroscopic analyses, including HRESITOF-MS and NMR (¹H, ¹³C, HSQC, HMBC and COSY). Compounds 2, 3 and 5 caused the inhibition on the growth of Trypanosoma cruzi (T. cruzi), with IC₅₀ values of 20.6, 19.4 and 26.9 μM, respectively, with moderate cytotoxicity against Vero cells. Compounds 1−5 were found to be inactive when tested against Plasmodium falciparum and Leishmania donovani, therefore showing selectivity against T. cruzi parasites.