Experimental and Clinical Treatment of Chagas Disease: A Review

Identification of Chagas disease biomarkers using untargeted metabolomics

Untargeted metabolomic analysis is a powerful tool used for the discovery of novel biomarkers. Chagas disease (CD), caused by Trypanosoma cruzi, is a neglected tropical disease that affects 6-7 million people with approximately 30% developing cardiac manifestations. The most significant clinical challenge lies in its long latency period after acute infection, and the lack of surrogate markers to predict disease progression or cure. In this cross-sectional study, we analyzed sera from 120 individuals divided into four groups: 31 indeterminate CD, 41 chronic chagasic cardiomyopathy (CCC), 18 Latin Americans with other cardiomyopathies and 30 healthy volunteers. Using a high-throughput panel of 986 metabolites, we identified three distinct profiles among individuals with cardiomyopathy, indeterminate CD and healthy volunteers. After a more stringent analysis, we identified some potential biomarkers. Among peptides, phenylacetylglutamine and fibrinopeptide B (1-13) exhibited an increasing trend from controls to ICD and CCC. Conversely, reduced levels of bilirubin and biliverdin alongside elevated urobilin correlated with disease progression. Finally, elevated levels of cystathionine, phenol glucuronide and vanillactate among amino acids distinguished CCC individuals from ICD and controls. Our novel exploratory study using metabolomics identified potential biomarker candidates, either alone or in combination that if confirmed, can be translated into clinical practice.

Organic solvent-free benznidazole nanosuspension as an approach to a novel pediatric formulation for Chagas disease

Aim: Benznidazole (BNZ), a class-II drug, is the primary treatment for Chagas disease, but its low aqueous solubility presents challenges in formulation and efficacy. Nanosuspensions (NS) could potentially address these issues. Methods: BNZ-NS were prepared using a simple, organic solvents-free nano-milling approach. Physicochemical characterizations were conducted on both NS and lyophilized solid-state BNZ-nanocrystals (NC). Results: BNZ-NS exhibited particle size <500 nm, an acceptable polydispersity index (0.23), high Z-potential, and physical stability for at least 90 days. BNZ-NC showed tenfold higher solubility than pure BNZ. Dissolution assays revealed rapid BNZ-NS dissolution. BNZ-NC demonstrated biocompatibility on an eukaryotic cell and enhanced BNZ efficacy against trypomastigotes of Trypanosoma cruzi. Conclusion: BNZ-NS offers a promising alternative, overcoming limitations associated with BNZ for optimized pharmacotherapy.

Tackling the challenges of human Chagas disease: A comprehensive review of treatment strategies in the chronic phase and emerging therapeutic approaches

Chagas disease (CD), caused by the flagellated protozoan Trypanosoma cruzi (T. cruzi), affects approximately 7 million people worldwide and is endemic in Latin America, especially among socioeconomically disadvantaged populations. Since the 1960s, only two drugs have been commercially available for treating this illness: nifurtimox (NFX) and benznidazole (BZN). Although these drugs are effective in the acute phase (AP) of the disease, in which parasitemia is usually high, their cure rates in the chronic phase (CP) are low and often associated with several side effects. The CP is characterized by a subpatent parasitaemia and absence of clinical symptoms in the great majority of infected individuals. However, at least 30 % of the individuals will develop potentially lethal symptomatic forms, including cardiac and digestive manifestations. For such reason, in the CP the treatment is usually symptomatic and typically focuses on managing complications such as arrhythmias, heart failure, or digestive problems. Therefore, the need for new drugs or therapeutic approaches using BZN or NFX is extremely urgent. This review presents the main clinical trials, especially in the CP, which involve BZN and NFX in different treatment regimens. Additionally, other therapies using combinations of these drugs with other substances such as allopurinol, itraconazole, ravuconazole, ketoconazole, posaconazole and amiodarone are also reported. The importance of early diagnosis, especially in pediatric patients, is also discussed, emphasizing the need to identify the disease in its early stages to improve the chances of successful treatment.

Bioactivity of synthetic peptides from Ecuadorian frog skin secretions against Leishmania mexicana, Plasmodium falciparum, and Trypanosoma cruzi

Chagas disease, leishmaniasis, and malaria are major parasitic diseases disproportionately affecting the underprivileged population in developing nations. Finding new, alternative anti-parasitic compounds to treat these diseases is crucial because of the limited number of options currently available, the side effects they cause, the need for long treatment courses, and the emergence of drug-resistant parasites. Anti-microbial peptides (AMPs) derived from amphibian skin secretions are small bioactive molecules capable of lysing the cell membrane of pathogens while having low toxicity against human cells. Here, we report the anti-parasitic activity of five AMPs derived from skin secretions of three Ecuadorian frogs: cruzioseptin-1, cruzioseptin-4 (CZS-4), and cruzioseptin-16 from Cruziohyla calcarifer; dermaseptin-SP2 from Agalychnis spurrelli; and pictuseptin-1 from Boana picturata. These five AMPs were chemically synthesized. Initially, the hemolytic activity of CZS-4 and its minimal inhibitory concentration against Escherichia coli, Staphylococcus aureus, and Candida albicans were determined. Subsequently, the cytotoxicity of the synthetic AMPs against mammalian cells and their anti-parasitic activity against Leishmania mexicana promastigotes, erythrocytic stages of Plasmodium falciparum and mammalian stages of Trypanosoma cruzi were evaluated in vitro. The five AMPs displayed activity against the pathogens studied, with different levels of cytotoxicity against mammalian cells. In silico molecular docking analysis suggests this bioactivity may occur via pore formation in the plasma membrane, resulting in microbial lysis. CZS-4 displayed anti-bacterial, anti-fungal, and anti-parasitic activities with low cytotoxicity against mammalian cells. Further studies about this promising AMP are required to gain a better understanding of its activity.IMPORTANCEChagas disease, malaria, and leishmaniasis are major tropical diseases that cause extensive morbidity and mortality, for which available treatment options are unsatisfactory because of limited efficacy and side effects. Frog skin secretions contain molecules with anti-microbial properties known as anti-microbial peptides. We synthesized five peptides derived from the skin secretions of different species of tropical frogs and tested them against cultures of the causative agents of these three diseases, parasites known as Trypanosoma cruzi, Plasmodium falciparum, and Leishmania mexicana. All the different synthetic peptides studied showed activity against one of more of the parasites. Peptide cruzioseptin-4 is of special interest since it displayed intense activity against parasites while being innocuous against cultured mammalian cells, which indicates it does not simply hold general toxic properties; rather, its activity is specific against the parasites.

Mapping the transporter-substrate interactions of the Trypanosoma cruzi NB1 nucleobase transporter reveals the basis for its high affinity and selectivity for hypoxanthine and guanine and lack of nucleoside uptake

Trypanosoma cruzi is a protozoan parasite and the etiological agent of Chagas disease, a debilitating and sometimes fatal disease that continues to spread to new areas. Yet, Chagas disease is still only treated with two related nitro compounds that are insufficiently effective and cause severe side effects. Nucleotide metabolism is one of the known vulnerabilities of T. cruzi, as they are auxotrophic for purines, and nucleoside analogues have been shown to have genuine promise against this parasite in vitro and in vivo. Since purine antimetabolites require efficient uptake through transporters, we here report a detailed characterisation of the T. cruzi NB1 nucleobase transporter with the aim of elucidating the interactions between TcrNB1 and its substrates and finding the positions that can be altered in the design of novel antimetabolites without losing transportability. Systematically determining the inhibition constants (Ki) of purine analogues for TcrNB1 yielded their Gibbs free energy of interaction, ΔG0. Pairwise comparisons of substrate (hypoxanthine, guanine, adenine) and analogues allowed us to determine that optimal binding affinity by TcrNB1 requires interactions with all four nitrogen residues of the purine ring, with N1 and N9, in protonation state, functioning as presumed hydrogen bond donors and unprotonated N3 and N7 as hydrogen bond acceptors. This is the same interaction pattern as we previously described for the main nucleobase transporters of Trypanosoma brucei spp. and Leishmania major and makes it the first of the ENT-family genes that is functionally as well as genetically conserved between the three main kinetoplast pathogens.

New drug discovery strategies for the treatment of benznidazole-resistance in Trypanosoma cruzi, the causative agent of Chagas disease

INTRODUCTION

Benznidazole, the drug of choice for treating Chagas Disease (CD), has significant limitations, such as poor cure efficacy, mainly in the chronic phase of CD, association with side effects, and parasite resistance. Understanding parasite resistance to benznidazole is crucial for developing new drugs to treat CD.

AREAS COVERED

Here, the authors review the current understanding of the molecular basis of benznidazole resistance. Furthermore, they discuss the state-of-the-art methods and critical outcomes employed to evaluate the efficacy of potential drugs against T. cruzi, aiming to select better compounds likely to succeed in the clinic. Finally, the authors describe the different strategies employed to overcome resistance to benznidazole and find effective new treatments for CD.

EXPERT OPINION

Resistance to benznidazole is a complex phenomenon that occurs naturally among T. cruzi strains. The combination of compounds that inhibit different metabolic pathways of the parasite is an important strategy for developing a new chemotherapeutic protocol.

Synthesis and Anti-Trypanosoma cruzi Activity of 3-Cyanopyridine Derivatives

Chagas disease (CD) is a parasitic neglected tropical disease (NTD) caused by the protozoan Trypanosoma cruzi that affects 6 million people worldwide, often resulting in financial burden, morbidity, and mortality in endemic regions. Given a lack of highly efficient and safe treatments, new, affordable, and fit-for-purpose drugs for CD are urgently needed. In this work, we present a hit-to-lead campaign for novel cyanopyridine analogues as antichagasic agents. In a phenotypic screening against intracellular T. cruzi, hits 1 and 2 were identified and displayed promising potency combined with balanced physicochemical properties. As part of the Lead Optimization Latin America consortium, a set of 40 compounds was designed, synthesized, and tested against T. cruzi intracellular amastigotes and relevant human cell lines. The structural modifications were focused on three positions: cyanopyridine core, linker, and right-hand side. The ADME properties of selected compounds, lipophilicity, kinetic solubility, permeability, and liver microsomal stability, were evaluated. Compounds 1-9 displayed good potency (EC50T. cruzi amastigote <1 μM), and most compounds did not present significant cytotoxicity (CC50 MRC-5 = 32-64 μM). Despite the good balance between potency and selectivity, the antiparasitic activity of the series appeared to be driven by lipophilicity, making the progression of the series unfeasible due to poor ADME properties and potential promiscuity issues.

Improving in vitro screening compounds anti-Trypanosoma cruzi by GFP-expressing parasites

BACKGROUND

Conventional microscopic counting is a widely utilised method for evaluating the trypanocidal effects of drugs on intracellular amastigotes. This is a low-cost approach, but it is time-consuming and reliant on the expertise of the microscopist. So, there is a pressing need for developing technologies to enhance the efficiency of low-cost anti-Trypanosoma cruzi drug screening.

OBJECTIVES

In our laboratory, we aimed to expedite the screening of anti-T. cruzi drugs by implementing a fluorescent method that correlates emitted fluorescence from green fluorescent protein (GFP)-expressing T. cruzi (Tc-GFP) with cellular viability.

METHODS

Epimastigotes (Y strain) were transfected with the pROCKGFPNeo plasmid, resulting in robust and sustained GFP expression across epimastigotes, trypomastigotes, and intracellular amastigotes. Tc-GFP epimastigotes and intracellular amastigotes were exposed to a serial dilution of benznidazole (Bz). Cell viability was assessed through a combination of microscopic counting, MTT, and fluorimetry.

FINDINGS

The fluorescence data indicated an underestimation of the activity of Bz against epimastigotes (IC50 75 µM x 14 µM). Conversely, for intracellular GFP-amastigotes, both fluorimetry and microscopy yielded identical IC50 values. Factors influencing the fluorimetry approach are discussed.

MAIN CONCLUSIONS

Our proposed fluorometric assessment is effective and can serve as a viable substitute for the time-consuming microscopic counting of intracellular amastigotes.

Chagas Disease: Comparison of Therapy with Nifurtimox and Benznidazole in Indigenous Communities in Colombia

Background: For indigenous people in Colombia, high infection rates with Chagas disease (CD) are known. Methods: In 2018 and 2020, nine villages were screened for CD. CD-positive patients could enter a drug observed treatment. While, in 2018, Benznidazole (BNZ) was provided as the first-line drug by the government, nifurtimox (NFX) was administered in 2020. Results: Of 121 individuals treated with BNZ, 79 (65%) suffered from at least one adverse event (AE). Of 115 treated with NFX, at least one AE occurred in 96 (84%) patients. In 69% of BNZ cases, the side effects did not last longer than one day; this applied to 31% of NFX cases. Excluding extreme outlier values, average duration of AEs differed highly significantly: BNZ (M = 0.7, SD = 1.4) and NFX (M = 1.7, SD = 1.5, p < 0.001). Using an intensity scale, AEs were highly significantly more severe for NFX (M = 2.1, SD = 0.58) compared to BZN (M = 1.1, SD = 0.38), p < 0.001. When analyzing the duration in relation to the intensity, the burden of AEs caused by NFX was significantly more pronounced. Dropouts (n = 2) due to AEs were in the NFX-group only. Conclusions: Side effects caused by BNZ were significantly fewer, as well as milder, shorter in duration, and more easily treatable, compared to NFX.

Neutrophils versus Protozoan Parasites: Plasmodium, Trichomonas, Leishmania, Trypanosoma, and Entameoba

Neutrophils are the most abundant polymorphonuclear granular leukocytes in human blood and are an essential part of the innate immune system. Neutrophils are efficient cells that eliminate pathogenic bacteria and fungi, but their role in dealing with protozoan parasitic infections remains controversial. At sites of protozoan parasite infections, a large number of infiltrating neutrophils is observed, suggesting that neutrophils are important cells for controlling the infection. Yet, in most cases, there is also a strong inflammatory response that can provoke tissue damage. Diseases like malaria, trichomoniasis, leishmaniasis, Chagas disease, and amoebiasis affect millions of people globally. In this review, we summarize these protozoan diseases and describe the novel view on how neutrophils are involved in protection from these parasites. Also, we present recent evidence that neutrophils play a double role in these infections participating both in control of the parasite and in the pathogenesis of the disease.

The End Justifies the Means: Chagas Disease from a Perspective of the Host-Trypanosoma cruzi Interaction

The neglected Chagas disease (CD) is caused by the protozoan parasite Trypanosoma cruzi. Despite CD dispersion throughout the world, it prevails in tropical areas affecting mainly poor communities, causing devastating health, social and economic consequences. Clinically, CD is marked by a mildly symptomatic acute phase, and a chronic phase characterized by cardiac and/or digestive complications. Current treatment for CD relies on medications with strong side effects and reduced effectiveness. The complex interaction between the parasite and the host outlines the etiology and progression of CD. The unique characteristics and high adaptability of T. cruzi, its mechanisms of persistence, and evasion of the immune system seem to influence the course of the disease. Despite the efforts to uncover the pathology of CD, there are many gaps in understanding how it is established and reaches chronicity. Also, the lack of effective treatments and protective vaccines constitute challenges for public health. Here, we explain the background in which CD is established, from the peculiarities of T. cruzi molecular biology to the development of the host's immune response leading to the pathophysiology of CD. We also discuss the state of the art of treatments for CD and current challenges in basic and applied science.

Omega-3 and omega-6 polyunsaturated fatty acids and their potential therapeutic role in protozoan infections

Protozoa exert a serious global threat of growing concern to human, and animal, and there is a need for the advancement of novel therapeutic strategies to effectively treat or mitigate the impact of associated diseases. Omega polyunsaturated fatty acids (ω-PUFAs), including Omega-3 (ω-3) and omega-6 (ω-6), are constituents derived from various natural sources, have gained significant attention for their therapeutic role in parasitic infections and a variety of essential structural and regulatory functions in animals and humans. Both ω-3 and ω-6 decrease the growth and survival rate of parasites through metabolized anti-inflammatory mediators, such as lipoxins, resolvins, and protectins, and have both in vivo and in vitro protective effects against various protozoan infections. The ω-PUFAs have been shown to modulate the host immune response by a commonly known mechanism such as (inhibition of arachidonic acid (AA) metabolic process, production of anti-inflammatory mediators, modification of intracellular lipids, and activation of the nuclear receptor), and promotion of a shift towards a more effective immune defense against parasitic invaders by regulation the inflammation like prostaglandins, leukotrienes, thromboxane, are involved in controlling the inflammatory reaction. The immune modulation may involve reducing inflammation, enhancing phagocytosis, and suppressing parasitic virulence factors. The unique properties of ω-PUFAs could prevent protozoan infections, representing an important area of study. This review explores the clinical impact of ω-PUFAs against some protozoan infections, elucidating possible mechanisms of action and supportive therapy for preventing various parasitic infections in humans and animals, such as toxoplasmosis, malaria, coccidiosis, and chagas disease. ω-PUFAs show promise as a therapeutic approach for parasitic infections due to their direct anti-parasitic effects and their ability to modulate the host immune response. Additionally, we discuss current treatment options and suggest perspectives for future studies. This could potentially provide an alternative or supplementary treatment option for these complex global health problems.

Efficacy of three benznidazole dosing strategies for adults living with chronic Chagas disease (MULTIBENZ): an international, randomised, double-blind, phase 2b trial

BACKGROUND

Treatment with benznidazole for chronic Chagas disease is associated with low cure rates and substantial toxicity. We aimed to compare the parasitological efficacy and safety of 3 different benznidazole regimens in adult patients with chronic Chagas disease.

METHODS

The MULTIBENZ trial was an international, randomised, double-blind, phase 2b trial performed in Argentina, Brazil, Colombia, and Spain. We included participants aged 18 years and older diagnosed with Chagas disease with two different serological tests and detectable T cruzi DNA by qPCR in blood. Previously treated people, pregnant women, and people with severe cardiac forms were excluded. Participants were randomly assigned 1:1:1, using a balanced block randomisation scheme stratified by country, to receive benznidazole at three different doses: 300 mg/day for 60 days (control group), 150 mg/day for 60 days (low dose group), or 400 mg/day for 15 days (short treatment group). The primary outcome was the proportion of patients with a sustained parasitological negativity by qPCR during a follow-up period of 12 months. The primary safety outcome was the proportion of people who permanently discontinued the treatment. Both primary efficacy analysis and primary safety analysis were done in the intention-to-treat population. The trial is registered with EudraCT, 2016-003789-21, and ClinicalTrials.gov, NCT03191162, and is completed.

FINDINGS

From April 20, 2017, to Sept 20, 2020, 245 people were enrolled, and 234 were randomly assigned: 78 to the control group, 77 to the low dose group, and 79 to the short treatment group. Sustained parasitological negativity was observed in 42 (54%) of 78 participants in the control group, 47 (61%) of 77 in the low dose group, and 46 (58%) of 79 in the short treatment group. Odds ratios were 1·41 (95% CI 0·69-2·88; p=0·34) when comparing the low dose and control groups and 1·23 (0·61-2·50; p=0·55) when comparing short treatment and control groups. 177 participants (76%) had an adverse event: 62 (79%) in the control group, 56 (73%) in the low dose group, and 59 (77%) in the short treatment group. However, discontinuations were less frequent in the short treatment group compared with the control group (2 [2%] vs 11 [14%]; OR 0·20, 95% CI 0·04-0·95; p=0·044).

INTERPRETATION

Participants had a similar parasitological responses. However, reducing the usual treatment from 8 weeks to 2 weeks might maintain the same response while facilitating adherence and increasing treatment coverage. These findings should be confirmed in a phase 3 clinical trial.

FUNDING

European Community's 7th Framework Programme.

Evaluation and discovery of novel benzothiazole derivatives as promising hits against Leishmania infantum

An early exploration of the benzothiazole class against two kinetoplastid parasites, Leishmania infantum and Trypanosoma cruzi, has been performed after the identification of a benzothiazole derivative as a suitable antileishmanial initial hit. The first series of derivatives focused on the acyl fragment of its class, evaluating diverse linear and cyclic, alkyl and aromatic substituents, and identified two other potent compounds, the phenyl and cyclohexyl derivatives. Subsequently, new compounds were designed to assess the impact of the presence of diverse substituents on the benzothiazole ring or the replacement of the endocyclic sulfur by other heteroatoms. All compounds showed relatively low cytotoxicity, resulting in decent selectivity indexes for the most active compounds. Ultimately, the in vitro ADME properties of these compounds were assessed, revealing a satisfying water solubility, gastrointestinal permeability, despite their low metabolic stability and high lipophilicity. Consequently, compounds 5 and 6 were identified as promising hits for further hit-to-lead exploration within this benzothiazole class against L. infantum, thus providing promising starting points for the development of antileishmanial candidates.

Seroprevalence of Trypanosoma cruzi among children from Veracruz, Mexico: Epidemiological baseline for a control model based on Chagas disease active transmission

Introduction. In 2021, the Secretaría de Salud de México and the Pan American Health Organization launched an initiative to interrupt intra-domiciliary vector transmission of Trypanosoma cruzi based on the prevalence of Chagas disease in children. The Mexican State of Veracruz was leading this initiative. Objective. To estimate the seroprevalence of T. cruzi infection among children under 15 years of age from rural areas of Veracruz, México. Materials and methods. We identified eight localities of high priority from the Municipality of Tempoal, Veracruz, for baseline serology. Blood samples were collected on filter paper from 817 individuals between June and August 2017, for screening with a third-generation enzyme immunoassay. Reactive cases were confirmed by indirect hemagglutination, enzyme-linked immunosorbent assay, and indirect immunofluorescence tests on peripheral blood serum samples. We calculated seroprevalence and 95% confidence intervals (CI). Results. We confirmed Chagas disease cases in children under 15 years of age with a seroprevalence of 1,9% (95 % CI = 1,12-3,16) in the localities of Citlaltepetl, Cornizuelo, Cruz de Palma and Rancho Nuevo. Conclusions. These results indicate recent transmission of T. cruzi in these communities and allow to establish an epidemiological baseline for the design and implementation of a model focused on geographical areas with active transmission to advance toward the elimination of intra-domiciliary vector transmission of this parasite in Mexico.

Synthesis and Evaluation of (Bis)benzyltetrahydroisoquinoline Alkaloids as Antiparasitic Agents

Visceral leishmaniasis and Chagas disease are neglected tropical diseases (NTDs) that severely impact the developing world. With current therapies suffering from poor efficacy and safety profiles as well as emerging resistance, new drug leads are direly needed. In this work, 26 alkaloids (9 natural and 17 synthetic) belonging to the benzyltetrahydroisoquinoline (BI) family were evaluated against both the pro/trypomastigote and amastigote forms of the parasites Leishmania infantum and Trypanosoma cruzi, the causative agents of these diseases. These alkaloids were synthesized via an efficient and modular enantioselective approach based on Bischler-Napieralski cyclization/Noyori asymmetric transfer hydrogenation to build the tetrahydroisoquinoline core. The bis-benzyltetrahydroisoquinoline (BBI) alkaloids were prepared using an Ullmann coupling of two BI units to form the biaryl ether linkage, which enabled a comprehensive survey of the influence of BI stereochemistry on bioactivity. Preliminary studies into the mechanism of action against Leishmania mexicana demonstrate that these compounds interfere with the cell cycle, potentially through inhibition of kinetoplast division, which may offer opportunities to identify a new target/mechanism of action. Three of the synthesized alkaloids showed promising druglike potential, meeting the Drugs for Neglected Disease initiative (DNDi) criteria for a hit against Chagas disease.

The Potential Use of Peptides in the Fight against Chagas Disease and Leishmaniasis

Chagas disease and leishmaniasis are both neglected tropical diseases that affect millions of people around the world. Leishmaniasis is currently the second most widespread vector-borne parasitic disease after malaria. The World Health Organization records approximately 0.7-1 million newly diagnosed leishmaniasis cases each year, resulting in approximately 20,000-30,000 deaths. Also, 25 million people worldwide are at risk of Chagas disease and an estimated 6 million people are infected with Trypanosoma cruzi. Pentavalent antimonials, amphotericin B, miltefosine, paromomycin, and pentamidine are currently used to treat leishmaniasis. Also, nifurtimox and benznidazole are two drugs currently used to treat Chagas disease. These drugs are associated with toxicity problems such as nephrotoxicity and cardiotoxicity, in addition to resistance problems. As a result, the discovery of novel therapeutic agents has emerged as a top priority and a promising alternative. Overall, there is a need for new and effective treatments for Chagas disease and leishmaniasis, as the current drugs have significant limitations. Peptide-based drugs are attractive due to their high selectiveness, effectiveness, low toxicity, and ease of production. This paper reviews the potential use of peptides in the treatment of Chagas disease and leishmaniasis. Several studies have demonstrated that peptides are effective against Chagas disease and leishmaniasis, suggesting their use in drug therapy for these diseases. Overall, peptides have the potential to be effective therapeutic agents against Chagas disease and leishmaniasis, but more research is needed to fully investigate their potential.

In silico toxicologic profile and in vivo trypanocidal activity of estafietin, a sesquiterpene lactone isolated from Stevia alpina Griseb

Chagas disease is an infection caused by the protozoan Trypanosoma cruzi, affecting 6-8 million people worldwide. Only two drugs are available for its treatment, having a limited efficacy and adverse side-effects. Estafietin is a sesquiterpene lactone isolated from Stevia alpina with in vitro activity against T. cruzi and low cytotoxicity against mammalian cells. The aim of this work was to predict the toxicologic profile of estafietin by in silico methods and assess its in vivo activity on a murine model of Chagas disease. Estafietin showed low toxicity according to pkCSM web tool and passed the PAINS filter from PAINS-remover web server. The treatment of infected mice with 1 mg/Kg/day of estafietin for five consecutive days administrated by intraperitoneal route significatively decreased parasitemia levels and reduced inflammatory infiltrates and myocyte damage on muscle tissue. These results suggest that estafietin had effect both on acute and chronic stages of the infection.

Drug Repositioning: A Monetary Stratagem to Discover a New Application of Drugs

Drug repurposing, also referred to as drug repositioning or drug reprofiling, is a scientific approach to the detection of any new application for an already approved or investigational drug. It is a useful policy for the invention and development of new pharmacological or therapeutic applications of different drugs. The strategy has been known to offer numerous advantages over developing a completely novel drug for certain problems. Drug repurposing has numerous methodologies that can be categorized as target-oriented, drug-oriented, and problem-oriented. The choice of the methodology of drug repurposing relies on the accessible information about the drug molecule and like pharmacokinetic, pharmacological, physicochemical, and toxicological profile of the drug. In addition, molecular docking studies and other computer-aided methods have been known to show application in drug repurposing. The variation in dosage for original target diseases and novel diseases presents a challenge for researchers of drug repurposing in present times. The present review critically discusses the drugs repurposed for cancer, covid-19, Alzheimer's, and other diseases, strategies, and challenges of drug repurposing. Moreover, regulatory perspectives related to different countries like the United States (US), Europe, and India have been delineated in the present review.

In Vitro and in Vivo Study of a Photostable Quinone Compound with Enhanced Therapeutic Efficacy against Chagas Disease

Chagas disease, a neglected tropical disease caused by the protozoan Trypanosoma cruzi poses a significant health challenge in rural areas of Latin America. The current pharmacological options exhibit notable side effects, demand prolonged administration, and display limited efficacy. Consequently, there is an urgent need to develop drugs that are safe and clinically effective. Previously, we identified a quinone compound (designated as compound 2) with potent antiprotozoal activity, based on the chemical structure of komaroviquinone, a natural product renowned for its antitrypanosomal effects. However, compound 2 was demonstrated considerably unstable to light. In this study, we elucidated the structure of the light-induced degradation products of compound 2 and probed the correlation between the quinone ring's substituents and its susceptibility to light. Our findings led to the discovery of quinones with significantly enhanced light stability, some of which exhibiting antitrypanosomal activity. The most promising compound was evaluated for drug efficacy in a mouse model of Chagas disease, revealing where a notable reduction in blood parasitemia.

Evaluation of Anti-Trypanosoma cruzi Activity of Chemical Constituents from Baccharis sphenophylla Isolated Using High-Performance Countercurrent Chromatography

Endemic in 21 countries, Chagas disease, also known as American Trypanosomiasis, is a neglected tropical disease (NTD) caused by the protozoan parasite Trypanosoma cruzi. The available drugs for the treatment of this disease, benznidazole and nifurtimox, are outdated and display severe side effects. Thus, the discovery of new drugs is crucial. Based on our continuous studies aiming towards the discovery of natural products with anti-T. cruzi potential, the MeOH extract from aerial parts of Baccharis sphenophylla Dusén ex. Malme (Asteraceae) displayed activity against this parasite and was subjected to high-performance countercurrent chromatography (HPCCC), to obtain one unreported syn-labdane diterpene - sphenophyllol (1) - as well as the known compounds gaudichaudol C (2), ent-kaurenoic acid (3), hispidulin (4), eupafolin (5), and one mixture of di-O-caffeoylquinic acids (6-8). Compounds 1-8 were characterized by analysis of nuclear magnetic resonance (NMR) and mass spectrometry (MS) data. When tested against trypomastigote forms, isolated labdane diterpenes 1 and 2 displayed potent activity, with EC50 values of 20.1 μM and 2.9 μM, respectively. The mixture of chlorogenic acids 6-8, as well as the isolated flavones 4 and 5, showed significant activity against the clinically relevant amastigotes, with EC50 values of 24.9, 12.8, and 2.7 μM, respectively. Nonetheless, tested compounds 1-8 displayed no cytotoxicity against mammalian cells (CC50 > 200 μM). These results demonstrate the application of HPCCC as an important tool to isolate bioactive compounds from natural sources, including the antitrypanosomal extract from B. sphenophylla, allowing for the development of novel strategic molecular prototypes against tropical neglected diseases.

Clinical trials for Chagas disease: etiological and pathophysiological treatment

Chagas disease (CD) is caused by the flagellate protozoan Trypanosoma cruzi. It is endemic in Latin America. Nowadays around 6 million people are affected worldwide, and 75 million are still at risk. CD has two evolutive phases, acute and chronic. The acute phase is mostly asymptomatic, or presenting unspecific symptoms which makes it hard to diagnose. At the chronic phase, patients can stay in the indeterminate form or develop cardiac and/or digestive manifestations. The two trypanocide drugs available for the treatment of CD are benznidazole (BZ) and nifurtimox (NFX), introduced in the clinic more than five decades ago. WHO recommends treatment for patients at the acute phase, at risk of congenital infection, for immunosuppressed patients and children with chronic infection. A high cure rate is seen at the CD acute phase but better treatment schemes still need to be investigated for the chronic phase. There are some limitations within the use of the trypanocide drugs, with side effects occurring in about 40% of the patients, that can lead patients to interrupt treatment. In addition, patients with advanced heart problems should not be treated with BZ. This is a neglected disease, discovered 114 years ago that still has no drug effective for their chronic phase. Multiple social economic and cultural barriers influence CD research. The high cost of the development of new drugs, in addition to the low economical return, results in the lack of investment. More economic support is required from governments and pharmaceutical companies on the development of more research for CD treatment. Two approaches stand out: repositioning and combination of drugs, witch drastically decrease the cost of this process, when compared to the development of a new drug. Here we discuss the progress of the clinical trials for the etiological and pathophysiological treatment for CD. In summary, more studies are needed to propose a new drug for CD. Therefore, BZ is still the best option for CD. The trials in course should clarify more about new treatment regimens, but it is already possible to indicate that dosage and time of treatment need to be adjusted.

The economic burden of Chagas disease: A systematic review

BACKGROUND

Chagas disease (CD) is a neglected disease affecting millions worldwide, yet little is known about its economic burden. This systematic review is part of RAISE project, a broader study that aims to estimate the global prevalence, mortality, and health and economic burden attributable to chronic CD and Chronic Chagas cardiomyopathy. The objective of this study was to assess the main costs associated with the treatment of CD in both endemic and non-endemic countries.

METHODS

An electronic search of the Medline, Lilacs, and Embase databases was conducted until 31st, 2022, to identify and select economic studies that evaluated treatment costs of CD. No restrictions on place or language were made. Complete or partial economic analyses were included.

RESULTS

Fifteen studies were included, with two-thirds referring to endemic countries. The most commonly investigated cost components were inpatient care, exams, surgeries, consultation, drugs, and pacemakers. However, significant heterogeneity in the estimation methods and presentation of data was observed, highlighting the absence of standardization in the measurement methods and cost components. The most common component analyzed using the same metric was hospitalization. The mean annual hospital cost per patient ranges from $25.47 purchasing power parity US dollars (PPP-USD) to $18,823.74 PPP-USD, and the median value was $324.44 PPP-USD. The lifetime hospital cost per patient varies from $209,44 PPP-USD for general care to $14,351.68 PPP-USD for patients with heart failure.

DISCUSSION

Despite the limitations of the included studies, this study is the first systematic review of the costs of CD treatment. The findings underscore the importance of standardizing the measurement methods and cost components for estimating the economic burden of CD and improving the comparability of cost components magnitude and cost composition analysis. Finally, assessing the economic burden is essential for public policies designed to eliminate CD, given the continued neglect of this disease.

The pipeline for drugs for control and elimination of neglected tropical diseases: 2. Oral anti-infective drugs and drug combinations for off-label use

In its 'Road map for neglected tropical diseases 2021-2030', the World Health Organization outlined its targets for control and elimination of neglected tropical diseases (NTDs) and research needed to achieve them. For many NTDs, this includes research for new treatment options for case management and/or preventive chemotherapy. Our review of small-molecule anti-infective drugs recently approved by a stringent regulatory authority (SRA) or in at least Phase 2 clinical development for regulatory approval showed that this pipeline cannot deliver all new treatments needed. WHO guidelines and country policies show that drugs may be recommended for control and elimination for NTDs for which they are not SRA approved (i.e. for 'off-label' use) if efficacy and safety data for the relevant NTD are considered sufficient by WHO and country authorities. Here, we are providing an overview of clinical research in the past 10 years evaluating the anti-infective efficacy of oral small-molecule drugs for NTD(s) for which they are neither SRA approved, nor included in current WHO strategies nor, considering the research sponsors, likely to be registered with a SRA for that NTD, if found to be effective and safe. No such research has been done for yaws, guinea worm, Trypanosoma brucei gambiense human African trypanosomiasis (HAT), rabies, trachoma, visceral leishmaniasis, mycetoma, T. b. rhodesiense HAT, echinococcosis, taeniasis/cysticercosis or scabies. Oral drugs evaluated include sparfloxacin and acedapsone for leprosy; rifampicin, rifapentin and moxifloxacin for onchocerciasis; imatinib and levamisole for loiasis; itraconazole, fluconazole, ketoconazole, posaconazole, ravuconazole and disulfiram for Chagas disease, doxycycline and rifampicin for lymphatic filariasis; arterolane, piperaquine, artesunate, artemether, lumefantrine and mefloquine for schistosomiasis; ivermectin, tribendimidine, pyrantel, oxantel and nitazoxanide for soil-transmitted helminths including strongyloidiasis; chloroquine, ivermectin, balapiravir, ribavirin, celgosivir, UV-4B, ivermectin and doxycycline for dengue; streptomycin, amoxicillin, clavulanate for Buruli ulcer; fluconazole and isavuconazonium for mycoses; clarithromycin and dapsone for cutaneous leishmaniasis; and tribendimidine, albendazole, mebendazole and nitazoxanide for foodborne trematodiasis. Additional paths to identification of new treatment options are needed. One promising path is exploitation of the worldwide experience with 'off-label' treatment of diseases with insufficient treatment options as pursued by the 'CURE ID' initiative.

Optimization of the 2-arylquinazoline-4(3H)one scaffold for a selective and potent antitrypanosomal agent: modulation of the mechanism of action through chemical functionalization

We sought to identify a potent and selective antitrypanosomal agent through modulation of the mechanism of action of a 2-arylquinazoline scaffold as an antitrypanosomal agent via chemical functionalization at the 4-position. We wished to use the: (i) susceptibility of trypanosomatids towards nitric oxide (NO) and reactive oxygen species (ROS); (ii) capacity of the 4-substituted quinazoline system to act as an antifolate agent. Three quinazolin-based moieties that differed from each other by having at the 4-position key pharmacophores targeting the induction of NO and ROS production were evaluated in vitro against Leishmania infantum and Trypanosoma cruzi parasites and their modes of action were explored. Replacement of an oxygen moiety at the 4-position of the antifolate 2-arylquinazolin-4(3H)one by hydrazinyl and 5-nitrofuryl-hydrazinyl pharmacophores enhanced antitrypanosomatid activity significantly due to promotion of an additional mechanism beyond the antifolate response such as NO or ROS production, respectively. Among the three types of chemical functionalization, the 5-nitrofuryl-hydrazinyl moiety generated the most potent compounds. Compound 3b was a potential candidate thanks to its sub-micromolar response against the promastigotes/amastigotes of L. infantum and epimastigote of T. cruzi, moderate toxicity on macrophages (J774.1), good selectivity index (∼15.1-17.6) and, importantly, non-mutagenic effects. 2-Arylquinazoline could be an attractive platform to design new anti-trypanosomatid agents with the use of key pharmacophores.

Design, synthesis and biological evaluation of antiparasitic dinitroaniline-ether phospholipid hybrids

A series of nine novel ether phospholipid-dinitroaniline hybrids were synthesized in an effort to deliver more potent antiparasitic agents with improved safety profile compared to miltefosine. The compounds were evaluated for their in vitro antiparasitic activity against L. infantum, L.donovani, L. amazonensis, L. major and L. tropica promastigotes, L. infantum and L. donovani intracellular amastigotes, Trypanosoma brucei brucei and against different developmental stages of Trypanosoma cruzi. The nature of the oligomethylene spacer between the dinitroaniline moiety and the phosphate group, the length of the side chain substituent on the dinitroaniline and the choline or homocholine head group were found to affect both the activity and toxicity of the hybrids. The early ADMET profile of the derivatives did not reveal major liabilities. Hybrid 3, bearing an 11-carbon oligomethylene spacer, a butyl side chain and a choline head group, was the most potent analogue of the series. It exhibited a broad spectrum antiparasitic profile against the promastigotes of New and Old World Leishmania spp., against intracellular amastigotes of two L. infantum strains and L. donovani, against T. brucei and against T. cruzi Y strain epimastigotes, intracellular amastigotes and trypomastigotes. The early toxicity studies revealed that hybrid 3 showed a safe toxicological profile while its cytotoxicity concentration (CC50) against THP-1 macrophages being >100 μM. Computational analysis of binding sites and docking indicated that the interaction of hybrid 3 with trypanosomatid α-tubulin may contribute to its mechanism of action. Furthermore, compound 3 was found to interfere with the cell cycle in T. cruzi epimastigotes, while ultrastructural studies using SEM and TEM in T. cruzi showed that compound 3 affects cellular processes that result in changes in the Golgi complex, the mitochondria and the parasite's plasma membrane. The snapshot pharmacokinetic studies showed low levels of 3 after 24 h following oral administration of 100 mg/Kg, while, its homocholine congener compound 9 presented a better pharmacokinetic profile.

Use of Nanocarriers Containing Antitrypanosomal Drugs for the Treatment of Chagas Disease

Chagas disease, caused by the Trypanosoma cruzi parasitic protozoan, is a neglected tropical disease (NTD) of significant incidence in Latin America. Transmission to humans and other mammals is mainly via the vector insect from the Reduviidae family, popularly known as the kissing bug. There are other transmission means, such as through congenital transmission, blood transfusions, organ transplantations, and the consumption of contaminated food. For more than 50 years, the disease has been treated with benznidazole and nifurtimox, which are only effective during the acute phase of the disease. In addition to their low efficacy in the chronic phase, they cause many adverse effects and are somewhat selective. The use of nanocarriers has received significant attention due to their ability to encapsulate and release therapeutic agents in a controlled manner. Generally, their diameter ranges from 100 to 300 nanometers. The objective of this scoping review was to perform a search of the literature for the use of nanocarriers as an alternative for improving the treatment of Chagas disease and to suggest future research. Bibliographic searches were carried out in the Web of Science and PubMed scientific databases from January 2012 to May 2023, using the "Chagas disease and Trypanosoma cruzi and nanoparticles" keywords, seeking to gather the largest number of articles, which were evaluated using the inclusion and exclusion criteria. After analyzing the papers, the results showed that nanocarriers offer physiological stability and safety for the transport and controlled release of drugs. They can increase solubility and selectivity against the parasite. The in vitro assays showed that the trypanocidal activity of the drug was not impaired after encapsulation. In the in vivo assays, parasitemia reduction and high survival and cure rates in animals were obtained during both phases of the disease using lower doses when compared to the standard treatment. The scoping review showed that nanocarriers are a promising alternative for the treatment of Chagas disease.

Antiprotozoal Activity of Benzoylthiourea Derivatives against Trypanosoma cruzi: Insights into Mechanism of Action

For decades, only two nitroheterocyclic drugs have been used as therapeutic agents for Chagas disease. However, these drugs present limited effectiveness during the chronic phase, possess unfavorable pharmacokinetic properties, and induce severe adverse effects, resulting in low treatment adherence. A previous study reported that N-(cyclohexylcarbamothioyl) benzamide (BTU-1), N-(tert-butylcarbamothioyl) benzamide (BTU-2), and (4-bromo-N-(3-nitrophenyl) carbamothioyl benzamide (BTU-3) present selective antiprotozoal activity against all developmental forms of Trypanosoma cruzi Y strain. In this study, we investigated the mechanism of action of these compounds through microscopy and biochemical analyses. Transmission electron microscopy analysis showed nuclear disorganization, changes in the plasma membrane with the appearance of blebs and extracellular arrangements, intense vacuolization, mitochondrial swelling, and formation of myelin-like structures. Biochemical results showed changes in the mitochondrial membrane potential, reactive oxygen species content, lipid peroxidation, and plasma membrane fluidity. In addition, the formation of autophagic vacuoles was observed. These findings indicate that BTU-1, BTU-2, and BTU-3 induced profound morphological, ultrastructural, and biochemical alterations in epimastigote forms, triggering an autophagic-dependent cell death pathway.

What Do You Need to Know before Studying Chagas Disease? A Beginner's Guide

Chagas disease is one of the most important tropical infections in the world and mainly affects poor people. The causative agent is the hemoflagellate protozoan Trypanosoma cruzi, which circulates among insect vectors and mammals throughout the Americas. A large body of research on Chagas disease has shown the complexity of this zoonosis, and controlling it remains a challenge for public health systems. Although knowledge of Chagas disease has advanced greatly, there are still many gaps, and it is necessary to continue generating basic and applied research to create more effective control strategies. The aim of this review is to provide up-to-date information on the components of Chagas disease and highlight current trends in research. We hope that this review will be a starting point for beginners and facilitate the search for more specific information.

Kinetic and Structural Characterization of Trypanosoma cruzi Hypoxanthine-Guanine-Xanthine Phosphoribosyltransferases and Repurposing of Transition-State Analogue Inhibitors

Over 70 million people are currently at risk of developing Chagas Disease (CD) infection, with more than 8 million people already infected worldwide. Current treatments are limited and innovative therapies are required. Trypanosoma cruzi, the etiological agent of CD, is a purine auxotroph that relies on phosphoribosyltransferases to salvage purine bases from their hosts for the formation of purine nucleoside monophosphates. Hypoxanthine-guanine-xanthine phosphoribosyltransferases (HGXPRTs) catalyze the salvage of 6-oxopurines and are promising targets for the treatment of CD. HGXPRTs catalyze the formation of inosine, guanosine, and xanthosine monophosphates from 5-phospho-d-ribose 1-pyrophosphate and the nucleobases hypoxanthine, guanine, and xanthine, respectively. T. cruzi possesses four HG(X)PRT isoforms. We previously reported the kinetic characterization and inhibition of two isoforms, TcHGPRTs, demonstrating their catalytic equivalence. Here, we characterize the two remaining isoforms, revealing nearly identical HGXPRT activities in vitro and identifying for the first time T. cruzi enzymes with XPRT activity, clarifying their previous annotation. TcHGXPRT follows an ordered kinetic mechanism with a postchemistry event as the rate-limiting step(s) of catalysis. Its crystallographic structures reveal implications for catalysis and substrate specificity. A set of transition-state analogue inhibitors (TSAIs) initially developed to target the malarial orthologue were re-evaluated, with the most potent compound binding to TcHGXPRT with nanomolar affinity, validating the repurposing of TSAIs to expedite the discovery of lead compounds against orthologous enzymes. We identified mechanistic and structural features that can be exploited in the optimization of inhibitors effective against TcHGPRT and TcHGXPRT concomitantly, which is an important feature when targeting essential enzymes with overlapping activities.

TRYPANOSOMA CRUZI INFECTION IN THREE SLENDER-TAILED MEERKATS (SURICATA SURICATTA)

Trypanosoma cruzi is a protozoan parasite primarily transmitted by triatomine insects (Hemiptera: subfamily Reduviidae) and is the cause of Chagas disease (CD). This report describes three cases of CD in a mob of five slender-tailed meerkats (Suricata suricatta) living in an outdoor exhibit at one zoological institution in Texas. The index case was a 9.5-yr-old female that presented with ataxia, lethargy, and pleural effusion. This case was diagnosed with CD postmortem via cytology, T. cruzi PCR of whole blood and lung fluid, and histology. Blood was opportunistically collected from the remaining four meerkats 28 d after the death of the index case and tested by PCR and serology. The second case was a clinically normal 7.5-yr-old male that tested PCR and antibody positive and the third case was a clinically normal 9-yr-old female that tested PCR positive. The second animal presented depressed, with pneumonia, and with continuous shivering 53 d after blood collection, and clinically improved after treatment with antibiotics and supportive care. Fifteen days later, the animal was found minimally responsive and died shortly thereafter. Histologic examination revealed Trypanosoma sp. amastigotes in the myocardium and the tissue was positive for T. cruzi DNA. The third meerkat, which received two separate courses of benznidazole over a span of almost 2 yr, was monitored routinely by PCR and serology and appeared clinically normal until found dead on exhibit 93 d after completion of the second treatment. Myocardium was positive for T. cruzi DNA. To the authors' knowledge, this case series is the first to document Chagas disease in meerkats and features associated cytologic and histologic findings.

Transcriptomic analysis of benznidazole-resistant and susceptible Trypanosoma cruzi populations

BACKGROUND

Chagas disease (CD), caused by the parasite Trypanosoma cruzi, is a serious public health concern in Latin America. Nifurtimox and benznidazole (BZ), the only two drugs currently approved for the treatment of CD, have very low efficacies in the chronic phase of the disease and several toxic side effects. Trypanosoma cruzi strains that are naturally resistant to both drugs have been reported. We performed a comparative transcriptomic analysis of wild-type and BZ-resistant T. cruzi populations using high-throughput RNA sequencing to elucidate the metabolic pathways related to clinical drug resistance and identify promising molecular targets for the development of new drugs for treating CD.

METHODS

All complementary DNA (cDNA) libraries were constructed from the epimastigote forms of each line, sequenced and analysed using the Prinseq and Trimmomatic tools for the quality analysis, STAR as the aligner for mapping the reads against the reference genome (T. cruzi Dm28c-2018), the Bioconductor package EdgeR for statistical analysis of differential expression and the Python-based library GOATools for the functional enrichment analysis.

RESULTS

The analytical pipeline with an adjusted P-value of < 0.05 and fold-change > 1.5 identified 1819 transcripts that were differentially expressed (DE) between wild-type and BZ-resistant T. cruzi populations. Of these, 1522 (83.7%) presented functional annotations and 297 (16.2%) were assigned as hypothetical proteins. In total, 1067 transcripts were upregulated and 752 were downregulated in the BZ-resistant T. cruzi population. Functional enrichment analysis of the DE transcripts identified 10 and 111 functional categories enriched for the up- and downregulated transcripts, respectively. Through functional analysis we identified several biological processes potentially associated with the BZ-resistant phenotype: cellular amino acid metabolic processes, translation, proteolysis, protein phosphorylation, RNA modification, DNA repair, generation of precursor metabolites and energy, oxidation-reduction processes, protein folding, purine nucleotide metabolic processes and lipid biosynthetic processes.

CONCLUSIONS

The transcriptomic profile of T. cruzi revealed a robust set of genes from different metabolic pathways associated with the BZ-resistant phenotype, proving that T. cruzi resistance mechanisms are multifactorial and complex. Biological processes associated with parasite drug resistance include antioxidant defenses and RNA processing. The identified transcripts, such as ascorbate peroxidase (APX) and iron superoxide dismutase (Fe-SOD), provide important information on the resistant phenotype. These DE transcripts can be further evaluated as molecular targets for new drugs against CD.

Arylimidamides Have Potential for Chemoprophylaxis against Blood-Transmitted Chagas Disease

Chagas disease (CD) affects over 6 million people worldwide and can be transmitted iatrogenically. Crystal violet (CV) was previously used for pathogen reduction but has harmful side-effects. In the present study, three arylimidamides (AIAs) and CV were used to sterilize mice blood samples experimentally contaminated with bloodstream trypomastigotes (BT) of Trypanosoma cruzi, at non hemolytic doses. All AIAs were not toxic to mouse blood cells until the highest tested concentration (96 µM). The previous treatment of BT with the AIAs impaired the infection establishment of cardiac cell cultures. In vivo assays showed that pre-incubation of mouse blood samples with the AIAs and CV (96 µM) significantly suppressed the parasitemia peak, but only the AIA DB1831 gave ≥90% animal survival, while vehicle treated samples reached 0%. Our findings support further studies regarding the potential use of AIAs for blood bank purposes.

Effectiveness of Nitazoxanide and Electrolyzed Oxiding Water in Treating Chagas Disease in a Canine Model

Chagas disease (CD) is caused by the protozoan Trypanosoma cruzi, and affects seven million people in Latin America. Side effects and the limited efficacy of current treatment have led to new drug research. The objective of this work was to evaluate the effectiveness of nitazoxanide (NTZ) and electrolyzed oxidizing water (EOW) in a canine model of experimental CD. Náhuatl dogs were infected with the T. cruzi H8 strain and NTZ- or EOW-treated orally for 10 days. Seronegativity was shown at 12 months post-infection (mpi) in the NTZ-, EOW-, and benznidazole (BNZ)-treated groups. The NTZ and BNZ groups had high levels of IFN-γ, TNF-α, IL-6, IL-12B, and IL-1β at 1.5 mpi and low levels of IL-10. Electrocardiographic studies showed alterations from 3 mpi and worsening at 12 mpi; NTZ treatment produced fewer cardiac pathomorphological changes compared to EOW, similar to BNZ treatment. There was no cardiomegaly in any group. In conclusion, although NTZ and EOW did not prevent changes in cardiac conductivity, they were able to avoid the severity of heart damage in the chronic phase of CD. NTZ induced a favorable proinflammatory immune response after infection, being a better option than EOW as a possible treatment for CD after BNZ.

Sulfonamide derived from anacardic acid as potential antichagasic: a theoretical approach based on molecular docking, molecular dynamics, and density functional theory calculations

Chagas disease (CD) is a tropical disease caused by the parasite Trypanosoma cruzi, transmitted by the barber insect. Currently, there are approximately 7 million infected people in the world, and it is estimated that 70 million people could contract this disease. The anacardic acid (AA) showed effectiveness in in silico and in vitro tests. The antichagasic potential of five sulfonamide molecules, derived from anacardic acid, was evaluated from a molecular approach based on the density functional theory (DFT), molecular dynamics (MD), and molecular docking (docking) calculations. Methyl 2-methoxy-6- (8- (methylsulfonamide) octyl) benzoate (SA1); 2-methoxy-6- (8- (phenylsulfonamide) octyl) benzoate (SA2); methyl 2-methoxy-6- (8- (2methylphenyl sulfonamide) octyl) benzoate (SA3); methyl 2-methoxy-6- (8-(methylphenylsulfonamide)octyl)benzoate (SA4); methyl2-(8-(2,5-dimethylphenylsulfonamide)octyl)-6-methoxybenzoate (SA5) were the investigated molecules. The DFT calculations were performed using the B3LYP/6-311+G (d, p) level of theory. The global and local reactivity data showed that SA1 shows the highest molecular reactivity, while SA2 is the most stable derivative. In addition, the structures of investigated molecules were confirmed by the linear correlations higher than 0.98 displayed between the experimental and calculated spectroscopic data (IR and NMR). Molecular docking of the molecules showed a greater prominence for the SA1, SA2, and SA4 molecules in the results of distances of ligand-cruzain. In molecular dynamics, SA2 obtained better stability due to greater interactions with important amino acids of cruzain.

In silico and in vitro assessment of anti-Trypanosoma cruzi efficacy, genotoxicity and pharmacokinetics of pentasubstituted pyrrolic Atorvastatin-aminoquinoline hybrid compounds

Atorvastatin (AVA) is a third-generation statin with several pleiotropic effects, considered the last synthetic pharmaceutical blockbuster. Recently, our group described the effects of AVA on DNA damage prevention and against Trypanosoma cruzi infection. In this study, our aim was to evaluate the efficacy, safety, and in silico pharmacokinetic profile of four hybrids of aminoquinolines with AVA 4a-d against T. cruzi using in vitro and in silico models. These synthetic compounds were designed by hybridization of the pentapyrrolic moiety of AVA with the aminoquinolinic unit of chloroquine or primaquine. Pharmacokinetics (ADME) and toxicity parameters were predicted by SwissADME, admetSAR and LAZAR in silico algorithms. The trypanocidal activity of AVA-quinoline hybrids were evaluated in vitro against amastigotes and trypomastigotes of T. cruzi, from Y (Tc II) and Tulahuen (Tc VI) strains. In vitro cardiocytotoxicity was assessed using primary cultures of mouse embryonic cardiac cells and in vitro hepatocytotoxicity on bidimensional and 3D-cultured HepG2 cells. Genotoxicity was evaluated by Ames test and micronucleus assay. Despite the overall good in silico ADMET profile, all tested compounds were predicted to be hepatotoxic. All hybrid derivatives presented high trypanocidal activity, against both trypomastigote and intracellular forms of T. cruzi, presenting EC₅₀'s lower than 1 µM besides superior selectivity than the reference drug, without evidences of cardiotoxicity in vitro. The compounds 4a and 4b presented a time-dependent toxicity in monolayer culture of HepG2 but no detectable toxic effects in their spheroids, opposing to the in silico prediction. We can conclude that the AVA-aminoquinoline hybrids presented a hit profile as antiparasitic agents in synthetic pharmaceutical innovation platforms.

Further Investigations of Nitroheterocyclic Compounds as Potential Antikinetoplastid Drug Candidates

Due to the lack of specific vaccines, management of the trypanosomatid-caused neglected tropical diseases (sleeping sickness, Chagas disease and leishmaniasis) relies exclusively on pharmacological treatments. Current drugs against them are scarce, old and exhibit disadvantages, such as adverse effects, parenteral administration, chemical instability and high costs which are often unaffordable for endemic low-income countries. Discoveries of new pharmacological entities for the treatment of these diseases are scarce, since most of the big pharmaceutical companies find this market unattractive. In order to fill the pipeline of compounds and replace existing ones, highly translatable drug screening platforms have been developed in the last two decades. Thousands of molecules have been tested, including nitroheterocyclic compounds, such as benznidazole and nifurtimox, which had already provided potent and effective effects against Chagas disease. More recently, fexinidazole has been added as a new drug against African trypanosomiasis. Despite the success of nitroheterocycles, they had been discarded from drug discovery campaigns due to their mutagenic potential, but now they represent a promising source of inspiration for oral drugs that can replace those currently on the market. The examples provided by the trypanocidal activity of fexinidazole and the promising efficacy of the derivative DNDi-0690 against leishmaniasis seem to open a new window of opportunity for these compounds that were discovered in the 1960s. In this review, we show the current uses of nitroheterocycles and the novel derived molecules that are being synthesized against these neglected diseases.

A functional assay using human whole blood and flow cytometry analysis to evaluate cytotoxicity and immunomodulatory effect of anti-Trypanosoma cruzi drugs

The discovery and development of new drugs for the treatment of Chagas disease is urgent due to the high toxicity and low cure efficacy, mainly during the chronic phase of this disease. Other chemotherapeutic approaches for Chagas disease treatment are being researched and require screening assays suitable for evaluating the effectivity of new biologically active compounds. This study aims to evaluate a functional assay using the internalization of epimastigotes forms of Trypanosoma cruzi by human peripheral blood leukocytes from healthy volunteers and analyses by flow cytometry of cytotoxicity, anti-T. cruzi activity, and immunomodulatory effect of benznidazole, ravuconazole, and posaconazole. The culture supernatant was used to measure cytokines (IL-1-β, IL-6, INF-γ, TNF and IL-10) and chemokines (MCP-1/CCL2, CCL5/RANTES and CXCL8/IL-8). The data showed a reduction in the internalization of T. cruzi epimastigote forms treated with ravuconazole, demonstrating its potential anti-T. cruzi activity. In addition, an increased amount of IL-10 and TNF cytokines was observed in the supernatant of cultures upon the addition of the drug, mainly IL-10 in the presence of benznidazole, ravuconazole and posaconazole, and TNF in the presence of ravuconazole and posaconazole. Moreover, the results revealed a decrease in the MCP-1/CCL2 index in cultures in the presence of benznidazole, ravuconazole, and posaconazole. A decrease in the CCL5/RANTES and CXCL8/IL-8 index in cultures with BZ, when compared to the culture without drugs, was also observed. In conclusion, the innovative functional test proposed in this study may be a valuable tool as a confirmatory test for selecting promising compounds identified in prospecting programs for new drugs for Chagas disease treatment.

Antimicrobial Peptides (AMPs): Potential Therapeutic Strategy against Trypanosomiases?

Trypanosomiases are a group of tropical diseases that have devastating health and socio-economic effects worldwide. In humans, these diseases are caused by the pathogenic kinetoplastids Trypanosoma brucei, causing African trypanosomiasis or sleeping sickness, and Trypanosoma cruzi, causing American trypanosomiasis or Chagas disease. Currently, these diseases lack effective treatment. This is attributed to the high toxicity and limited trypanocidal activity of registered drugs, as well as resistance development and difficulties in their administration. All this has prompted the search for new compounds that can serve as the basis for the development of treatment of these diseases. Antimicrobial peptides (AMPs) are small peptides synthesized by both prokaryotes and (unicellular and multicellular) eukaryotes, where they fulfill functions related to competition strategy with other organisms and immune defense. These AMPs can bind and induce perturbation in cell membranes, leading to permeation of molecules, alteration of morphology, disruption of cellular homeostasis, and activation of cell death. These peptides have activity against various pathogenic microorganisms, including parasitic protists. Therefore, they are being considered for new therapeutic strategies to treat some parasitic diseases. In this review, we analyze AMPs as therapeutic alternatives for the treatment of trypanosomiases, emphasizing their possible application as possible candidates for the development of future natural anti-trypanosome drugs.

Novel Diarylthioether Compounds as Agents for the Treatment of Chagas Disease

Herein, we describe the hit optimization of a novel diarylthioether chemical class found to be active against Trypanosoma cruzi; the parasite responsible for Chagas disease. The hit compound was discovered through a whole-cell phenotypic screen and as such, the mechanism of action for this chemical class is unknown. Our investigations led to clear structure-activity relationships and the discovery of several analogues with high in vitro potency. Furthermore, we observed excellent activity during acute in vivo efficacy studies in mice infected with transgenic T. cruzi. These diarylthioether compounds represent a promising new chemotype for Chagas disease drug discovery and merit further development to increase oral exposure without increasing toxicity.

Effect of statins on inflammation and cardiac function in patients with chronic Chagas disease: A protocol for pathophysiological studies in a multicenter, placebo-controlled, proof-of-concept phase II trial

BACKGROUND

Cardiac complications, including heart failure and arrhythmias, are the leading causes of disability and death in Chagas disease (CD). CD, caused by the Trypanosoma cruzi parasite, afflicts 7 million people in Latin America, and its incidence is increasing in non-endemic countries due to migration. The cardiac involvement is explained by parasite-dependent, immune-mediated myocardial injury, microvascular abnormalities, and ischemia. Current treatment of early CD includes the administration of nifurtimox and benznidazole. However, their efficacy is low in the chronic phase and may induce severe adverse events, forcing therapy to halt. Therefore, finding innovative approaches to treat this life-threatening tropical disease is of utmost importance. Thus, improving the efficacy of the current antichagasic drugs by modifying the inflammatory response would render the current treatment more effective. It has been reported that, in mice, simvastatin decreases cardiac inflammation and endothelial activation, and improves cardiac function, effects that require clinical confirmation.

OBJECTIVE

The study aims to analyze whether two doses of Atorvastatin, administered after CD treatment is completed, are safe and more efficacious than the antiparasitic drugs alone in reducing general inflammation and improving endothelial and cardiac functions in a proof-of-concept, placebo-controlled phase II trial.

METHODS

300 subjects will be recruited from four Chilean hospitals with an active Program for the Control of Chagas Disease. 40 or 80 mg/day of atorvastatin or placebo will be administered after completion of the antichagasic therapy. The patients will be followed up for 12 months. Efficacy will be determined by measuring changes in plasma levels of anti-inflammatory and pro-inflammatory cytokines, soluble cell adhesion molecules, BNP, and cTnT. Also, the resting 12-lead ECG and a 2D-echocardiogram will be obtained to evaluate cardiac function.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04984616.

Effect of B-NIPOx in Experimental Trypanosoma cruzi Infection in Mice

Chagas disease is caused by Trypanosoma cruzi and represents a major public health problem, which is endemic in Latin America and emerging in the rest of the world. The two drugs that are currently available for its treatment, Benznidazole and Nifurtimox, are partially effective in the chronic phase of the disease. In this study, we designed and synthesized the benzyl ester of N-isopropyl oxamic acid (B-NIPOx), which is a non-polar molecule that crosses cell membranes. B-NIPOx is cleaved inside the parasite by carboxylesterases, releasing benzyl alcohol (a molecule with antimicrobial activity), and NIPOx, which is an inhibitor of α-hydroxy acid dehydrogenase isozyme II (HADH-II), a key enzyme in T. cruzi metabolism. We evaluated B-NIPOx cytotoxicity, its toxicity in mice, and its inhibitory activity on purified HADH-II and on T. cruzi homogenates. We then evaluated the trypanocidal activity of B-NIPOx in vitro and in vivo and its effect in the intestine of T. cruzi-infected mice. We found that B-NIPOx had higher trypanocidal activity on epimastigotes and trypomastigotes than Benznidazole and Nifurtimox, that it was more effective to reduce blood parasitemia and amastigote nests in infected mice, and that, in contrast to the reference drugs, it prevented the development of Chagasic enteropathy.

Repurposing of 5‐nitrofuran‐3,5‐disubstituted isoxazoles: A thriving scaffold to antitrypanosomal agents

Chagas disease (CD) is a neglected disease caused by the protozoan Trypanosoma cruzi. The two drugs used in the treatment schedules exhibit adverse effects and severe toxicity. Thus, searching for new antitrypanosomal agents is urgent to provide improved treatments to those affected by this disease. 5-Nitrofuran-isoxazole analogs were synthesized by cycloaddition reactions [3+2] between chloro-oximes and acetylenes in satisfactory yields. We analyzed the structure-activity relationship of the analogs based on Hammett's and Hansch's parameters. The 5-nitrofuran-isoxazole analogs exhibited relevant in vitro antitrypanosomal activity against the amastigote forms of T. cruzi. Analog 7s was the trending hit of the series, showing an IC₅₀ value of 40 nM and a selectivity index of 132.50. A possible explanation for this result may be the presence of an electrophile near the isoxazole core. Moreover, the most active analogs proved to act as an in vitro substrate of type I nitroreductase rather than the cruzain, enzymes commonly investigated in molecular target studies of CD drug discovery. These findings suggest that 5-nitrofuran-isoxazole analogs are promising in the studies of agents for CD treatment.

The Trypanosoma cruzi TcrNT2 Nucleoside Transporter Is a Conduit for the Uptake of 5-F-2'-Deoxyuridine and Tubercidin Analogues

Among the scarce validated drug targets against Chagas disease (CD), caused by Trypanosoma cruzi, the parasite's nucleoside salvage system has recently attracted considerable attention. Although the trypanocidal activity of tubercidin (7-deazapurine) has long been known, the identification of a class of 7-substituted tubercidin analogs with potent in vitro and in vivo activity and much-enhanced selectivity has made nucleoside analogs among the most promising lead compounds against CD. Here, we investigate the recently identified TcrNT2 nucleoside transporter and its potential role in antimetabolite chemotherapy. TcrNT2, expressed in a Leishmania mexicana cell line lacking the NT1 nucleoside transporter locus, displayed very high selectivity and affinity for thymidine with a K_m of 0.26 ± 0.05 µM. The selectivity was explained by interactions of 2-oxo, 4-oxo, 5-Me, 3'-hydroxy and 5'-hydroxy with the transporter binding pocket, whereas a hydroxy group at the 2' position was deleterious to binding. This made 5-halogenated 2'-deoxyuridine analogues good substrates but 5-F-2'-deoxyuridine displayed disappointing activity against T. cruzi trypomastigotes. By comparing the EC₅₀ values of tubercidin and its 7-substituted analogues against L. mexicana Cas9, Cas9^ΔNT1 and Cas9^ΔNT1+TcrNT2 it was shown that TcrNT2 can take up tubercidin and, at a minimum, a subset of the analogs.

Chagas disease in Oklahoma

Chagas disease, caused by infection with the protozoan Trypanosoma cruzi, is one of the leading public health problems in the Western Hemisphere. The parasite is mainly transmitted by contact with infected insect vectors but other forms of transmission are important in endemic areas. In the United States, while the disease is largely restricted to immigrants from endemic countries in Latin America, there is some risk of local acquisition. T. cruzi circulates in a sylvatic cycle between mammals and local triatomine insects in the southern half of the country, where human residents may be at risk for incidental infection. There are several reported cases of locally-acquired Chagas disease in the United States, but there is a paucity of information in Oklahoma. We present a brief summary of the available data of Chagas disease in Oklahoma to raise awareness and serve as a foundation for future research.

Drug Repurposing in Chagas Disease: Chloroquine Potentiates Benznidazole Activity against Trypanosoma cruzi In Vitro and In Vivo

Drug combinations and drug repurposing have emerged as promising strategies to develop novel treatments for infectious diseases, including Chagas disease. In this study, we aimed to investigate whether the repurposed drugs chloroquine (CQ) and colchicine (COL), known to inhibit Trypanosoma cruzi infection in host cells, could boost the anti- T. cruzi effect of the trypanocidal drug benznidazole (BZN), increasing its therapeutic efficacy while reducing the dose needed to eradicate the parasite. The combination of BZN and COL exhibited cytotoxicity to infected cells and low antiparasitic activity.

Disruption of multiple copies of the Prostaglandin F2alpha synthase gene affects oxidative stress response and infectivity in Trypanosoma cruzi

Chagas disease, caused by the protozoan Trypanosoma cruzi, is a serious chronic parasitic disease, currently treated with Nifurtimox (NFX) and Benznidazole (BZ). In addition to high toxicity, these drugs have low healing efficacy, especially in the chronic phase of the disease. The existence of drug-resistant T. cruzi strains and the occurrence of cross-resistance between BZ and NFX have also been described. In this context, it is urgent to study the metabolism of these drugs in T. cruzi, to better understand the mechanisms of resistance. Prostaglandin F2α synthase (PGFS) is an enzyme that has been correlated with parasite resistance to BZ, but the mechanism by which resistance occurs is still unclear. Our results show that the genome of the CL Brener clone of T. cruzi, contains five PGFS sequences and three potential pseudogenes. Using CRISPR/Cas9 we generated knockout cell lines in which all PGFS sequences were disrupted, as shown by PCR and western blotting analyses. The PGFS deletion did not alter the growth of the parasites or their susceptibility to BZ and NFX when compared to wild-type (WT) parasites. Interestingly, NTR-1 transcripts were shown to be upregulated in ΔPGFS mutants. Furthermore, the ΔPGFS parasites were 1.6 to 1.7-fold less tolerant to oxidative stress generated by menadione, presented lower levels of lipid bodies than the control parasites during the stationary phase, and were less infective than control parasites.

Platelets, Macrophages, and Thromboinflammation in Chagas Disease

Chagas disease (CD) is a major health problem in the Americas and an emerging health problem in Europe and other nonendemic countries. Several studies have documented persistence of the protozoan parasite Trypanosoma cruzi, and oxidative and inflammatory stress are major pathogenic factor. Mural and cardiac thrombi, cardiac arrhythmias, and cardiomyopathy are major clinical features of CD. During T. cruzi infection, parasite-released factors induce endothelial dysfunction along with platelet (PLT) and immune-cell activation. PLTs have a fundamental role in maintaining hemostasis and preventing bleeding after vascular injury. Excessive activation of PLTs and coagulation cascade can result in thrombosis and thromboembolic events, which are recognized to occur in seropositive individuals in early stages of CD when clinically symptomatic heart disease is not apparent. Several host and parasite factors have been identified to signal hypercoagulability and increase the risk of ischemic stroke in early phases of CD. Further, PLT interaction with immune cells and their role in host defense against pathogens and inflammatory processes have only recently been recognized and evolving. In the context of parasitic diseases, PLTs function in directly responding to T. cruzi infection, and PLT interactions with immune cells in shaping the proinflammatory or immunoregulatory function of monocytes, macrophages, and neutrophils remains elusive. How T. cruzi infection alters systemic microenvironment conditions to influence PLT and immune-cell interactions is not understood. In this review, we discuss the current literature, and extrapolate the mechanistic situations to explain how PLT and innate immune cell (especially monocytes and macrophages) interactions might be sustaining hypercoagulability and thromboinflammation in chronic CD.

New derivatives from dehydrodieugenol B and its methyl ether displayed high anti-Trypanosoma cruzi activity and cause depolarization of the plasma membrane and collapse the mitochondrial membrane potential

In the present work, dehydrodieugenol B (1) and its methyl ether (2), isolated from Nectandra leucantha twigs, were used as starting material for the preparation of two new derivatives (1a and 2a) containing an additional methoxycarbonyl unit on allyl side chains. Compounds 1a and 2a demonstrated activity against trypomastigotes (EC₅₀ values of 13.5 and 23.0 μM, respectively) and against intracellular amastigotes (EC₅₀ values of 10.2 and 6.1 μM, respectively). Additionally, compound 2a demonstrated no mammalian cytotoxicity up to 200 μM whereas compound 1a exhibited a CC₅₀ value of 139.8 μM. The mechanism of action studies of compounds 1a and 2a demonstrated a significant depolarization of the plasma membrane potential in trypomastigotes, followed by a mitochondrial membrane potential collapse. Neither calcium level nor reactive oxygen species alterations were observed after a short-time incubation. Considering the potential of compound 2a against T. cruzi and its simple preparation from the natural product 2, isolated from N. leucantha, this compound could be considered a new hit for future drug design studies in Chagas disease.

Xanthine Analogs Suppress Trypanosoma cruzi Infection In Vitro Using PDEs as Targets

Trypanosoma cruzi (T. cruzi), the causative agent of Chagas disease, has infected 6 million people, putting 70 million people at risk worldwide. Presently, very limited drugs are available, and these have severe side effects. Hence, there is an urgency to delve into other pathways and targets for novel drugs. Trypanosoma cruzi (T. cruzi) expresses a number of different cyclic AMP (cAMP)-specific phosphodiesterases (PDEs). cAMP is one of the key regulators of mammalian cell proliferation and differentiation, and it also plays an important role in T. cruzi growth. Very few studies have demonstrated the important role of cyclic nucleotide-specific PDEs in T. cruzi’s survival. T. cruzi phosphodiesterase C (TcrPDEC) has been proposed as a potential new drug target for treating Chagas disease. In the current study, we screen several analogs of xanthine for potency against trypomastigote and amastigote growth in vitro using three different strains of T. cruzi (Tulahuen, Y and CA-1/CL72). One of the potent analogs, GVK14, has been shown to inhibit all three strains of amastigotes in host cells as well as axenic cultures. In conclusion, xanthine analogs that inhibit T. cruzi PDE may provide novel alternative therapeutic options for Chagas disease.