nifurtimox and Disease-Models--Animal

Despite more than 100 years since it was firstly described Chagas disease, only two drugs are available to treat Chagas disease: Nifurtimox launched by Bayer in 1965 and benznidazole launched by Roche in 1971. Drug discovery initiatives have been looking for new compounds as an alternative to these old drugs. Although new platforms have been used with the latest technologies, a critical step on that process still relies on the in vivo model. Unfortunately, to date, available animal models have limited predictive value and there is no standardization. With the aim to better understand the role of benznidazole, the current standard of care of Chagas disease, we performed this review. We intend to analyze the influence of the experimental design of the most used animal model, the murine model, in the assessment of the efficacy endpoint.

Topics: Animals; Chagas Disease; Disease Models, Animal; Dose-Response Relationship, Drug; Humans; Mice; Nifurtimox; Nitroimidazoles; Trypanocidal Agents; Trypanosoma cruzi

Chagas disease (CD) is caused by the protozoan parasite

Topics: Animals; Chagas Disease; Chronic Disease; Clinical Trials as Topic; Disease Models, Animal; Drug Compounding; Humans; Incidence; Latin America; Nanoparticles; Nifurtimox; Nitroimidazoles; Observational Studies as Topic; Randomized Controlled Trials as Topic; Tissue Distribution; Trypanocidal Agents; Trypanosoma cruzi

Human African trypanosomiasis is causing thousands of deaths every year in the rural areas of sub-saharan Africa. There is a high unmet medical need since the approved drugs are poorly efficacious, show considerable toxicity and are not easy to administer. This work describes the optimization of the pharmacokinetic properties of a previously published family of triazine lead compounds. One compound (35 (UAMC-03011)) with potent anti-trypanosomal activity and no cytotoxicity was selected for further study because of its good microsomal stability and high selectivity for Trypanosoma brucei over a panel including Trypanosoma cruzi, L.eishmania infantum, and Plasmodium falciparum. In vivo pharmacokinetic parameters were determined and the compound was studied in an acute in vivo mouse disease model. One of the important learnings of this study was that the rate of trypanocidal activity is an important parameter during the lead optimization process.

Topics: Animals; Disease Models, Animal; Humans; Mice; Structure-Activity Relationship; Triazines; Tropolone; Trypanocidal Agents; Trypanosoma brucei brucei; Trypanosomiasis, African

Although many Trypanosoma cruzi (T. cruzi) strains isolated from a wide range of hosts have been characterized, there is a lack of information about biological features from vertically transmitted strains. We describe the molecular and biological characteristics of the T. cruzi VD strain isolated from a congenital Chagas disease patient. The VD strain was typified as DTU TcVI; in vitro sensitivity to nifurtimox (NFX) and beznidazole (BZ) were 2.88 μM and 6.19 μM respectively, while inhibitory concentrations for intracellular amastigotes were 0.24 μM for BZ, and 0.66 μM for NFX. Biological behavior of VD strain was studied in a mouse model of acute infection, resulting in high levels of parasitemia and mortality with a rapid clearence of bloodstream trypomastigotes when treated with BZ or NFX, preventing mortality and reducing parasitic load and intensity of inflammatory infiltrate in skeletal and cardiac muscle. Treatment-induced parasitological cure, evaluated after immunossupression were 41% and 35% for BZ and NFX treatment respectively, suggesting a partial response to these drugs in elimination of parasite burden. This exhaustive characterization of this T. cruzi strain provides the basis for inclusion of this strain in a panel of reference strains for drug screening and adds a new valuable tool for the study of experimental T. cruzi infection.

Topics: Animals; Brain; Chagas Disease; Chlorocebus aethiops; Disease Models, Animal; DNA, Protozoan; Female; Heart; Humans; Infant; Infectious Disease Transmission, Vertical; Inhibitory Concentration 50; Male; Mice; Mice, Inbred BALB C; Muscle, Skeletal; Myocardium; Nifurtimox; Nitroimidazoles; Parasitemia; Random Allocation; Trypanocidal Agents; Trypanosoma cruzi; Vero Cells

During Trypanosoma cruzi infection, oxidative stress is considered a contributing factor for dilated cardiomyopathy development. In this study, the effects of astaxanthin (ASTX) were evaluated as an alternative drug treatment for Chagas disease in a mouse model during the acute infection phase, given its anti-inflammatory, immunomodulating, and anti-oxidative properties. ASTX was tested in vitro in parasites grown axenically and in co-culture with Vero cells. In vivo tests were performed in BALB/c mice (4-6 weeks old) infected with Trypanosoma cruzi and supplemented with ASTX (10 mg/kg/day) and/or nifurtimox (NFMX; 100 mg/kg/day). Results show that ASTX has some detrimental effects on axenically cultured parasites, but not when cultured with mammalian cell monolayers. In vivo, ASTX did not have any therapeutic value against acute Trypanosoma cruzi infection, used either alone or in combination with NFMX. Infected animals treated with NFMX or ASTX/NFMX survived the experimental period (60 days), while infected animals treated only with ASTX died before day 30 post-infection. ASTX did not show any effect on the control of parasitemia; however, it was associated with an increment in focal heart lymphoplasmacytic infiltration, a reduced number of amastigote nests in cardiac tissue, and less hyperplasic spleen follicles when compared to control groups. Unexpectedly, ASTX showed a negative effect in infected animals co-treated with NFMX. An increment in parasitemia duration was observed, possibly due to ASTX blocking of free radicals, an anti-parasitic mechanism of NFMX. In conclusion, astaxanthin is not recommended during the acute phase of Chagas disease, either alone or in combination with nifurtimox.

Topics: Animals; Chagas Disease; Chlorocebus aethiops; Disease Models, Animal; Drug Therapy, Combination; Female; Heart; Malondialdehyde; Mice; Mice, Inbred BALB C; Myocardium; Nifurtimox; Organ Size; Parasitemia; Spleen; Trypanocidal Agents; Trypanosoma cruzi; Vero Cells; Xanthophylls

As chronic Chagas disease does not have a definitive treatment, the development of alternative therapeutic protocols is a priority. Dipyridamole (DPY) is an alternative to counteract the pathophysiological phenomena involved in Chagas cardiomyopathy.. To evaluate the therapeutic efficacy of DPY associated with nifurtimox (Nfx) in epimastigote axenic cultures and in mice with acute Chagas disease.. NMRI adult male mice were divided into nine groups: three healthy and six Trypanosoma cruzi-infected groups. Mice received vehicle, Nfx or DPY, alone or combined. The doses assayed were Nfx 10 and 40 mg/kg and DPY 30 mg/kg. The treatment efficacy was evaluated by clinical, electrocardiographic, parasitological, biochemical and histopathological methods.. In vitro, DPY and Nfx had a trypanocidal effect with IC50 values of 372 ± 52 and 21.53 ± 2.13 µM, respectively; DPY potentiated the Nfx effect. In vivo, Nfx (40 mg/kg) with or without DPY had a therapeutic effect, which was reflected in the 84-92% survival rate and elimination of parasitaemia and heart tissue amastigotes. Nfx (10 mg/kg) had a subtherapeutic effect with no survival and persistence of amastigotes, inflammation and fibrosis in heart tissue; adding DPY increased the survival rate to 85%, and all tested parameters were significantly improved.. DPY has a trypanocidal effect in vitro and enhances the Nfx therapeutic effect in an in vivo murine model.

Topics: Acute Disease; Animals; Chagas Cardiomyopathy; Dipyridamole; Disease Models, Animal; Drug Synergism; Drug Therapy, Combination; Male; Mice; Nifurtimox; Trypanocidal Agents

The clonal evolution of Trypanosoma cruzi sustains scientifically the hypothesis of association between parasite's genetic, biological behavior and possibly the clinical aspects of Chagas disease in patients from whom they were isolated. This study intended to characterize a range of biological properties of TcI, TcII and TcVI T. cruzi samples in order to verify the existence of these associations. Several biological features were evaluated, including in vitro epimastigote-growth, "Vero"cells infectivity and growth, along with in vivo studies of parasitemia, polymorphism of trypomastigotes, cardiac inflammation, fibrosis and response to treatment by nifurtimox during the acute and chronic murine infection. The global results showed that the in vitro essays (acellular and cellular cultures) TcII parasites showed higher values for all parameters (growth and infectivity) than TcVI, followed by TcI. In vivo TcII parasites were more virulent and originated from patients with severe disease. Two TcII isolates from patients with severe pathology were virulent in mice, while the isolate from a patient with the indeterminate form of the disease caused mild infection. The only TcVI sample, which displayed low values in all parameters evaluated, was also originated of an indeterminate case of Chagas disease. Response to nifurtimox was not associated to parasite genetic and biology, as well as to clinical aspects of human disease. Although few number of T. cruzi samples have been analyzed, a discreet correlation between parasite genetics, biological behavior in vitro and in vivo (murine model) and the clinical form of human disease from whom the samples were isolated was verified.

Topics: Animals; Cells, Cultured; Chagas Disease; Disease Models, Animal; Humans; Mice; Nifurtimox; Trypanocidal Agents; Trypanosoma cruzi; Virulence

Chagas disease is a neglected tropical disease with 6-7 million people infected worldwide, and there is no effective treatment. Therefore, there is an urgent need to continue researching in order to discover novel therapeutic alternatives. We present a series of arylaminoketone derivatives as means of identifying new drugs to treat Chagas disease in the acute phase with greater activity, less toxicity, and a larger spectrum of action than that corresponding to the reference drug benznidazole. Indexes of high selectivity found in vitro formed the basis for later in vivo assays in BALB/c mice. Murine model results show that compounds 3, 4, 7, and 10 induced a remarkable decrease in parasitemia levels in acute phase and the parasitemia reactivation following immunosuppression, and curative rates were higher than with benznidazole. These high antiparasitic activities encourage us to propose these compounds as promising molecules for developing an easy to synthesize anti-Chagas agent.

Topics: Animals; Cells, Cultured; Chagas Disease; Chlorocebus aethiops; Disease Models, Animal; Dose-Response Relationship, Drug; Mannich Bases; Mice; Mice, Inbred BALB C; Molecular Structure; Parasitic Sensitivity Tests; Structure-Activity Relationship; Trypanocidal Agents; Trypanosoma cruzi; Vero Cells

The insect-transmitted protozoan parasite Trypanosoma cruzi is the causative agent of Chagas disease, and infects 5-8 million people in Latin America. Chagas disease is characterised by an acute phase, which is partially resolved by the immune system, but then develops as a chronic life-long infection. There is a consensus that the front-line drugs benznidazole and nifurtimox are more effective against the acute stage in both clinical and experimental settings. However, confirmative studies have been restricted by difficulties in demonstrating sterile parasitological cure. Here, we describe a systematic study of nitroheterocyclic drug efficacy using highly sensitive bioluminescence imaging of murine infections. Unexpectedly, we find both drugs are more effective at curing chronic infections, judged by treatment duration and therapeutic dose. This was not associated with factors that differentially influence plasma drug concentrations in the two disease stages. We also observed that fexinidazole and fexinidazole sulfone are more effective than benznidazole and nifurtimox as curative treatments, particularly for acute stage infections, most likely as a result of the higher and more prolonged exposure of the sulfone derivative. If these findings are translatable to human patients, they will have important implications for treatment strategies.

Topics: Animals; Area Under Curve; Chagas Disease; Disease Models, Animal; Female; Male; Mice; Mice, Inbred BALB C; Mice, Inbred C3H; Nifurtimox; Nitroimidazoles; Treatment Outcome; Trypanocidal Agents; Trypanosoma cruzi

Trypanosoma brucei gambiense is the main causative agent of Human African Trypanosomiasis (HAT), also known as sleeping sickness. Because of limited alternatives and treatment toxicities, new therapeutic options are urgently needed for patients with HAT. Sterol 14alpha-demethylase (CYP51) is a potential drug target but its essentiality has not been determined in T. brucei. We used a tetracycline-inducible RNAi system to assess the essentiality of CYP51 in T. brucei bloodstream form (BSF) cells and we evaluated the effect of posaconazole, a well-tolerated triazole drug, within a panel of virulent strains in vitro and in a murine model. Expression of CYP51 in several T. brucei cell lines was demonstrated by western blot and its essentiality was demonstrated by RNA interference (CYP51RNAi) in vitro. Following reduction of TbCYP51 expression by RNAi, cell growth was reduced and eventually stopped compared to WT or non-induced cells, showing the requirement of CYP51 in T. brucei. These phenotypes were rescued by addition of ergosterol. Additionally, CYP51RNAi induction caused morphological defects with multiflagellated cells (p<0.05), suggesting cytokinesis dysfunction. The survival of CYP51RNAi Doxycycline-treated mice (p = 0.053) and of CYP51RNAi 5-day pre-induced Doxycycline-treated mice (p = 0.008) were improved compared to WT showing a CYP51 RNAi effect on trypanosomal virulence in mice. The posaconazole concentrations that inhibited parasite growth by 50% (IC50) were 8.5, 2.7, 1.6 and 0.12 μM for T. b. brucei 427 90-13, T. b. brucei Antat 1.1, T. b. gambiense Feo (Feo/ITMAP/1893) and T. b. gambiense Biyamina (MHOM/SD/82), respectively. During infection with these last three virulent strains, posaconazole-eflornithine and nifurtimox-eflornithine combinations showed similar improvement in mice survival (p≤0.001). Our results provide support for a CYP51 targeting based treatment in HAT. Thus posaconazole used in combination may represent a therapeutic alternative for trypanosomiasis.

Topics: 14-alpha Demethylase Inhibitors; Animals; Anti-Bacterial Agents; Cytokinesis; Disease Models, Animal; Doxycycline; Eflornithine; Ergosterol; Humans; Mice; Nifurtimox; Phenotype; RNA Interference; Sterol 14-Demethylase; Triazoles; Trypanocidal Agents; Trypanosoma brucei brucei; Trypanosomiasis, African

In this paper, the design, synthesis and biological evaluation of a set of quinazoline-2,4,6-triamine derivatives (1-9) as trypanocidal, antileishmanial and antiplasmodial agents are explained. The compounds were rationalized basing on docking studies of the dihydrofolate reductase (DHFR from Trypanosoma cruzi, Leishmania major and Plasmodium vivax) and pteridin reductase (PTR from T. cruzi and L. major) structures. All compounds were in vitro screened against both bloodstream trypomastigotes of T. cruzi (NINOA and INC-5 strains) and promatigotes of Leishmania mexicana (MHOM/BZ/61/M379 strain), and also for cytotoxicity using Vero cell line. Against T. cruzi, three compounds (5, 6 and 8) were the most effective showing a better activity profile than nifurtimox and benznidazole (reference drugs). Against L. mexicana, four compounds (5, 6, 8, and 9) exhibited the highest activity, even than glucantime (reference drug). In the cytotoxicity assay, protozoa were more susceptible than Vero cells. In vivo Plasmodium berghei assay (ANKA strain), the compounds 1, 5, 6 and 8 showed a more comparable activity than chloroquine and pyrimethamine (reference drugs) when they were administrated by the oral route. The antiprotozoal activity of these substances, endowed with redox properties, represented a good starting point for a medicinal chemistry program aiming for chemotherapy of Chagas' disease, leishmaniosis and malaria.

Topics: Administration, Oral; Animals; Antimalarials; Antiprotozoal Agents; Chlorocebus aethiops; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Design; Female; Leishmania major; Malaria; Mice; Mice, Inbred Strains; Models, Molecular; Molecular Structure; Parasitic Sensitivity Tests; Plasmodium vivax; Quinazolines; Structure-Activity Relationship; Trypanosoma cruzi; Vero Cells

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

Topics: Animals; Binding Sites; Cell Line; Chagas Disease; Disease Models, Animal; Leishmania donovani; Mice; Mice, Inbred BALB C; Nitroreductases; Parasitic Sensitivity Tests; Prodrugs; Protein Structure, Tertiary; Protozoan Proteins; Rats; Sterol 14-Demethylase; Structure-Activity Relationship; Triazoles; Trypanocidal Agents; Trypanosoma brucei rhodesiense; Trypanosoma cruzi

Chagas disease, which is caused by Trypanosoma cruzi, is a major health problem in Latin America, and there are currently no drugs for the effective treatment of this disease. The energy metabolism of T. cruzi is an attractive target for drug design, and we previously reported that inhibitors of α-hydroxy acid dehydrogenase (HADH)-isozyme II exhibit trypanocidal activity. N-Propyl oxamate (NPOx) is an inhibitor of HADH-isozyme II, and its non-polar ethyl ester (Et-NPOx) is cytotoxic to T. cruzi. A new derivative of NPOx has been developed in this study with higher trypanocidal activity, which could be used for the treatment of Chagas disease.. The benzyl ester of NPOx (B-NPOx) was synthesized and its activity evaluated towards epimastigotes and bloodstream trypomastigotes (in vitro), as well as mice infected with T. cruzi (in vivo). The activity of B-NPOx was also compared with those of Et-NPOx, benznidazole (Bz) and nifurtimox (Nx). NINOA, Miguz, Compostela, Nayarit and INC-5 T. cruzi strains were used in this study.. Polar NPOx did not penetrate the parasites and exhibited no trypanocidal activity. In contrast, the hydrophobic ester B-NPOx exhibited trypanocidal activity in vitro and in vivo. B-NPOx exhibited higher trypanocidal activity than Et-NPOx, Bz and Nx towards all five of the T. cruzi strains. The increased activity of B-NPOx was attributed to its hydrolysis inside the parasites to give NPOx and benzyl alcohol, which is an antimicrobial compound with trypanocidal effects. B-NPOx was also effective against two strains of T. cruzi that are resistant to Bz and Nx.. B-NPOx exhibited higher in vitro (2- to 14.8-fold) and in vivo (2.2- to 4.5-fold) trypanocidal activity towards T. cruzi than Et-NPOx. B-NPOx also exhibited higher in vitro (2- to 24-fold) and in vivo (1.9- to 15-fold) trypanocidal activity than Bz and Nx. B-NPOx is more lipophilic than Et-NPOx, allowing for better penetration into T. cruzi parasites, where the enzymatic cleavage of B-NPOx would give NPOx and benzyl alcohol, which are potent trypanocidal agents. Taken together with its low toxicity, these results suggest that B-NPOx could be used as a potent prodrug for the treatment of Chagas disease.

Topics: Alcohol Oxidoreductases; Animals; Cell Line; Cell Survival; Chagas Disease; Disease Models, Animal; Esters; Isoenzymes; Male; Mice; Nifurtimox; Nitroimidazoles; Oxamic Acid; Prodrugs; Trypanocidal Agents; Trypanosoma cruzi

The present work aimed to investigate the curative effect of benznidazole (BZL) in combination with other patented drugs [nifurtimox (NFX), posaconazole (POS) or AmBisome(®) (AMB)] in mice acutely or chronically infected with either a BZL-susceptible (Tulahuen) or a BZL-partially-resistant (Y) strain of Trypanosoma cruzi. To appreciate the eventual advantage of such combinations, infected mice were treated for short durations (non-curative) of each individual treatment. Cure rates were determined by investigating blood parasites (microscopic examination) and parasite DNA (quantitative PCR) after submitting treated mice to immune suppression with cyclophosphamide. The results mainly suggest that shorter durations of treatment combining BZL and POS or NFX might cure mice acutely or chronically infected with the Tulahuen strain, whereas the combination of BZL with AMB does not have such an effect. Moreover, the association BZL+POS does not improve the curative effect of POS (all used for shorter durations) in infection with the Y strain. Shortening the duration of treatment whilst keeping a complete curative effect deserves interest in limiting adverse reactions due to dose-cumulative toxic effects of long treatment. Genotyping of the T. cruzi strain(s) infecting patients might also allow a better adaptation of individual therapeutic schedules, improving both the efficiency and safety of trypanocidal treatment. This preliminary experimental study should encourage further investigations to find the best combination of adequate drug concentrations and timing of treatment.

Topics: Amphotericin B; Animals; Chagas Disease; Disease Models, Animal; DNA, Protozoan; Drug Therapy, Combination; Female; Mice; Mice, Inbred BALB C; Nifurtimox; Nitroimidazoles; Parasite Load; Parasitemia; Real-Time Polymerase Chain Reaction; Treatment Outcome; Triazoles; Trypanocidal Agents; Trypanosoma cruzi

During the first stage of human African trypanosomiasis (HAT), Trypanosoma brucei gambiense is found mainly in the blood, and pentamidine treatment is used. Pentamidine is predominantly ineffective once the parasites have invaded the central nervous system (CNS). This lack of efficacy is thought to be due to the inability of pentamidine to cross the blood-brain barrier, although this has never been explored directly. This study addresses this using brain perfusion in healthy mice, P-glycoprotein-deficient mice, and in a murine model of HAT (T. brucei brucei). The influence of additional antitrypanosomal drugs on pentamidine delivery to the CNS also was investigated. Results revealed that [(3)H]pentamidine can cross the blood-brain barrier, although a proportion was retained by the capillary endothelium and failed to reach the healthy or trypanosome-infected brain (up to day 21 p.i.). The CNS distribution of pentamidine was increased in the final (possibly terminal) stage of trypanosome infection, partly because of loss of barrier integrity (days 28-35 p.i.) as measured by [(14)C]sucrose and [(3)H]suramin. Furthermore, pentamidine distribution to the CNS involved influx and efflux [via P-glycoprotein and multidrug resistance-associated protein (MRP)] transporters and was affected by the other antitrypanosomal agents, suramin, melarsoprol, and nifurtimox, but not eflornithine. These interactions could contribute to side effects or lead to the development of parasite resistance to the drugs. Thus, great care must be taken when designing drug combinations containing pentamidine or other diamidine analogs. However, coadministration of P-glycoprotein and/or MRP inhibitors with pentamidine or other diamidines might provide a means of improving efficacy against CNS stage HAT.

Topics: Adenine; Adenosine; Animals; ATP Binding Cassette Transporter, Subfamily B; Biological Transport; Blood-Brain Barrier; Brain; Cerebrospinal Fluid; Disease Models, Animal; Drug Interactions; Eflornithine; Indomethacin; Male; Melarsoprol; Mice; Mice, Inbred BALB C; Mice, Inbred Strains; Mice, Knockout; Multidrug Resistance-Associated Proteins; Nifurtimox; Pentamidine; Perfusion; Suramin; Trypanosoma brucei brucei; Trypanosomiasis, African

5-arylethenylbenzofuroxan derivatives with high in vitro anti-Trypanosoma cruzi activity were studied in vivo using acute murine models of Chagas' disease. The selected compounds, as pure isomeric forms, 1, 2, 3 and 4, or as equimolecular mixture of geometric isomers, 1:2, 3:4, 5:6 were studied against different T. cruzi strains. Consequently, Tulahuen 2 strain, Colombiana strain (resistant to Nifurtimox and Benznidazole), and two different wild strains, one isolated from the wild reservoir Didelphis marsupialis and another one from Uruguayan patients, were selected. No relevant signs of in vivo toxicity were observed with the benzofuroxans orally administered. Compound 1 and the mixture of isomers 1:2 were the best for treating infection against the four studied strains.

Topics: Acute Disease; Animals; Antibodies, Protozoan; Benzoxazoles; Chagas Disease; Disease Models, Animal; Female; Mice; Parasitemia; Treatment Outcome; Trypanosoma cruzi

L-buthionine (S,R)-sulfoximine (BSO) at a dose of 220 mg/kg of body weight/day showed an anti-Trypanosoma cruzi effect in infected mice, increasing their survival rate and decreasing the parasitemias and parasite burden in the hearts. Treatment with BSO plus nifurtimox caused an increase in the survival rate in comparison to the rates with treatment with each drug alone.

Topics: Acute Disease; Animals; Buthionine Sulfoximine; Chagas Disease; Disease Models, Animal; Drug Synergism; Drug Therapy, Combination; Mice; Mice, Inbred BALB C; Nifurtimox; Survival Rate; Trypanocidal Agents; Trypanosoma cruzi

Chagas' disease, caused by the parasite Trypanosoma cruzi, remains the leading cause of cardiopathy in Latin America with about 12 million people infected. Classic clinical manifestations derive from infection of muscle cells leading to progressive cardiomyopathy, while some patients develop megacolon or megaesophagus. A very aggressive clinical course including fulminant meningoencephalitis has been reported in patients who contract Chagas' disease in the background of immunodeficiency. This includes patients with human immunodeficiency virus infection as well as patients receiving immunosuppressive therapy for organ transplant. Currently, only two drugs are approved for the treatment of Chagas' disease, nifurtimox and benznidazole. Both have significant limitations due to common and serious side effects as well as limited availability. A promising group of new drug leads for Chagas' disease is cysteine protease inhibitors targeting cruzain, the major protease of T. cruzi. The inhibitor N-methyl-Pip-F-homoF-vinyl sulfonyl phenyl (N-methyl-Pip-F-hF-VS phi) is in late-stage preclinical development. Therefore, the question arose as to whether protease inhibitors targeting cruzain would have efficacy in Chagas' disease occurring in the background of immunodeficiency. To address this question, we studied the course of infection in recombinase-deficient (Rag1(-/-)) and normal mice infected with T. cruzi. Infections localized to heart and skeletal muscle in untreated normal animals, while untreated Rag1(-/-) mice showed severe infection in all organs and predominantly in liver and spleen. Treatment with the dipeptide N-methyl-Pip-F-hF-VS phi rescued immunodeficient animals from lethal Chagas' infection. The majority (60 to 100%) of inhibitor-treated Rag1(-/-) mice had increased survival, negative PCR, and normal tissues by histopathological examination.

Topics: Animals; Cattle; Cells, Cultured; Chagas Disease; Cysteine Endopeptidases; Cysteine Proteinase Inhibitors; Disease Models, Animal; Female; Homeodomain Proteins; Humans; Mice; Mice, Inbred C3H; Mice, Inbred C57BL; Mice, Knockout; Nifurtimox; Nitroimidazoles; Protozoan Proteins; Survival Analysis; Trypanocidal Agents; Trypanosoma cruzi

The trypanocidal activity of N-isopropyl oxamate (NIPOx) and the ethyl ester of N-isopropyl oxamate (Et-NIPOx) were tested on cultured epimastigotes (in vitro) and on murine trypanosomiasis (in vivo) using five different T. cruzi strains. When benznidazole and nifurtimox, used for comparison, were tested we found that only three of these T. cruzi strains were affected, whereas the other two strains, Miguz and Compostela, were resistant to the in vitro and the in vivo trypanocidal activity of these substances. In addition, when NIPOx was tested on cultured epimastigotes and on mice parasitaemia, trypanocidal activity was not obtained on either of these T. cruzi strains. Our experiments strongly suggest that NIPOx does not penetrate intact epimastigotes due to the polarity of its carboxylate whereas Et-NIPOx, acting as a prodrug, exhibited in vitro and in vivo trypanocidal activity in the five tested T. cruzi strains.

Topics: Alcohol Oxidoreductases; Animals; Disease Models, Animal; Dose-Response Relationship, Drug; Enzyme Inhibitors; Kinetics; Mice; Models, Chemical; NAD; Nifurtimox; Nitroimidazoles; Oxamic Acid; Species Specificity; Time Factors; Trypanocidal Agents; Trypanosoma cruzi; Trypanosomiasis

Chagas' disease, which is caused by Trypanosoma cruzi, remains essentially incurable. Due principally to a lack of profit incentive, the pharmaceutical industry has had limited interest in developing new antichagasic drugs. Thus, a search for agents that exhibit activity against T. cruzi, although medicaments have been developed for the treatment of other diseases, seems justifiable. Responding to evidence that the principal biochemical differences between mammalian cells and African trypanosomes apply equally to T. cruzi, our evaluations were conducted. Previous work showed the effectiveness of anticancer agents against T. rhodesiense. In the present studies, 76 anticancer compounds were assessed for their ability to suppress the trypomastigotes of T. cruzi- infected mice. Five compounds were found to be active. The most effective was cycloheximide, which was more than six times as effective as the standard, nifurtimox.

Topics: Animals; Antineoplastic Agents; Berberine Alkaloids; Chagas Disease; Cycloheximide; Disease Models, Animal; Female; Mice; Nifurtimox; Quinolinium Compounds; Reserpine; Streptozocin

In the search for novel antitoxoplasmic agents, we evaluated the efficacy of nifurtimox (3-methyl-4[5'-nitrofurfurylidene-amino]-tetrahydroe-4H-1,4- thiazine-1,1-dioxide), an antiprotozoal drug effective against trypanosomiasis, in an experimental model of acute toxoplasmosis in mice. One hundred NIH mice were inoculated intraperitoneally, each with 2,614 RH tachyzoites of Toxoplasma gondii, and randomly allocated into 5 groups (n = 19-21). Animals from each group were orally treated for 10 days either with nifurtimox 25 mg/kg/day (NF1), nifurtimox 50 mg/kg/day (NF2), pyrimethamine 60 mg/kg/day (P), the combination nifurtimox 50 mg/kg/day plus pyrimethamine 60 mg/kg/day (NF2-P), or with corn oil (controls). Survival of mice was recorded daily for 1 mo after the experimental infection. Comparisons of cumulative mortality between groups were made applying the chi2 test. Mean survival time was longer in animals from P and NF2-P groups than those from NF1, NF2, and control groups. Cumulative mortality was less in mice from the NF2-P group (25%), than that in mice from the P (65%), the NF1 (100%), the NF2 (89%), or the control (95%) groups (P < 0.01). The doses of nifurtimox used in the present study were not significantly effective against murine toxoplasmosis. However, when combined with pyrimethamine, a strong anti-toxoplasma effect was obtained in comparison with survival rates associated with pyrimethamine or nifurtimox alone. It seems feasible that nifurtimox inhibits the replication of T. gondii tachyzoites similar to that of other protozoans, e.g., Trypanosoma and Leishmania. It will be important to determine if the reduction of mortality in mice treated with the nifurtimox-pyrimethamine combination results from summation or from synergism. Further studies on the toxic mechanisms exerted by nifurtimox on T. gondii seem warranted.

Topics: Administration, Oral; Animals; Antiprotozoal Agents; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Therapy, Combination; Male; Mice; Nifurtimox; Pyrimethamine; Random Allocation; Toxoplasmosis, Animal

If military forces are required to operate in areas that are endemic for Chagas' disease, the occupation should be of critical concern. These areas, located in Central and South America, are many. The matter is of particular importance because no suitable drug exists to treat individuals who contract the disease. We examined 60 compounds of a chemical class, thiosemicarbazones, known to have some activity against the disease. The work was carried out using Trypanosoma cruzi-infected mice. Of the 60 potential drugs evaluated, 12 showed significant suppressive activity. One of these compounds was almost 50% greater than the reference drug used in the test system.

Topics: Animals; Chagas Disease; Disease Models, Animal; Drug Evaluation, Preclinical; Female; Mice; Mice, Inbred Strains; Military Medicine; Nifurtimox; Thiosemicarbazones; Trypanocidal Agents

Forty-nine "standard" compounds known to be useful in the treatment of other diseases were tested for their suppressive activity against the trypomastigotes of Trypanosoma cruzi-infected mice. The most active was the antidepressant protriptyline, which was almost three times as effective as the reference drug, nifurtimox. A major value of the present data is to demonstrate the refractoriness of the T. cruzi parasite against many of the drug standards that have known biological activity.

Topics: Animals; Antiprotozoal Agents; Chagas Disease; Disease Models, Animal; Female; Imipramine; Ketoconazole; Mice; Mice, Inbred Strains; Nifurtimox; Nigericin; Niridazole; Protriptyline; Trypanosoma cruzi

Nine of 25 carefully selected compounds (from a stock of more than 200 000 chemical species amassed principally as a result of testing against other parasitic diseases) were found to have significant suppressive activity against the parasites in the blood of a Trypanosoma cruzi mouse model. Eight of these compounds evaluated in this model had suppressive activity equal to or greater than the reference compound, nifurtimox. For the first time, suppressive activity against T. cruzi is reported for a 7-aminoquinoline, a phosphonium salt, and TAC pamoate; The biological model is believed to be able to serve as a means of identifying other new "leads* in seeking drugs broadly effective against T=ruzi infections in man.

Topics: 5-Amino-3-((5-nitro-2-furyl)vinyl)-1,2,4-oxadiazole; Aminoquinolines; Animals; Chagas Disease; Disease Models, Animal; Male; Mice; Nifurtimox; Onium Compounds; Structure-Activity Relationship; Trityl Compounds; Trypanocidal Agents; Trypanosoma cruzi