RESUMEN

Chagas heart disease (CHD), caused by the protozoan parasite Trypanosoma cruzi, consists of a progressive myocarditis which may lead to congestive heart failure or sudden death. Previous work from our laboratory has demonstrated that the experimental infection of mice with T. cruzi positively modulates the expression of CD40 by myocardial cells, whose ligation potentiates IFN-γ-induced IL-6 production. Herein, we investigate the role of the CD40/CD40L interaction during T. cruzi infection using a CD40-targeted peptide and evaluating parasitological, histopathological and serological parameters. To reproduce acute and chronic phases of theT. cruzi infection, we used two experimental models: Balb/c mice infected with RA strain of T. cruzi (Balb/c-RA) and C3H/HeN mice infected with Sylvio X-10/4 parasites (C3H/HeN-Sylvio), respectively. Balb/c-RA treated with CD40-tageted peptide since day 0 post infection (pi), were unable to control the acute infection dying within 23-26 days pi with marked tissue damage. In contrast, treatment of C3H/HeN-Sylvio treated with CD40-targeted peptide starting on day 30 pi resulted in amelioration of myocardial and skeletal muscle damage. Altogether, our results indicate a dual role of CD40/CD40L dyad in the control of T.cruzi infection as well as the associated pathology, depending on the timing of treatment initiation.

Asunto(s)

Enfermedad de Chagas , Trypanosoma cruzi , Animales , Ratones , Ratones Endogámicos C3H , Ligando de CD40 , Antígenos CD40 , Ratones Endogámicos BALB C

RESUMEN

The purpose of this study was to evaluate the efficacy of imiquimod-containing nanovesicles prepared with lipids extracted from the hyperhalophile archaebacterium Halorubrum tebenquichense (nanoARC-IMQ) to induce protection against Trypanosoma cruzi infection. The therapeutic efficacy of archaeolipid nanovesicles was assessed in an experimental murine model of acute infection with T. cruzi. The administration of nanoARQ-IMQ prevented mortality as compared to infected untreated animals, reduced parasitemia levels and diminished myocardial and musculoskeletal lesions in mice infected with a lethal strain of T. cruzi. Our findings suggest that the immunotherapy with nanoARC-IMQ has potential to limit the progression of Chagas disease.

Asunto(s)

Adyuvantes Inmunológicos/uso terapéutico , Enfermedad de Chagas/terapia , Imiquimod/uso terapéutico , Inmunoterapia , Nanopartículas/uso terapéutico , Adyuvantes Inmunológicos/química , Animales , Enfermedad de Chagas/patología , Imiquimod/química , Lípidos/química , Masculino , Ratones , Ratones Endogámicos C3H , Nanopartículas/química , Tamaño de la Partícula , Propiedades de Superficie

RESUMEN

Chagas disease is one of the main neglected diseases in the world, being endemic in 21 countries of Latin America. This disease has become a global health problem due to migration of infected people non-endemic countries. Even though this disease affects millions of people, only two drugs are approved for its treatment, benznidazole and nifurtimox, and both have several limitations. We have previously reported the synthesis and biological activity against T. cruzi of polysubstituted quinolines analogous to natural products. Herein, we present the synthesis of rationally-based novel analogous of this family of compounds. All the evaluated compounds presented trypanocidal activity. Three of them (6, 7 and 10) stand out for their selectivity indexes. Ethyl 2-((4-benzyl-1,4-diazepan-1-yl)methyl)-6-chloro-4-phenylquinoline-3-carboxylate (compound 10) was found to display anti-parasite activity, presenting the highest selectivity index. Apart from controlling in vivo the parasitemia levels, compound 10 was able to prevent tissue inflammation, a key factor to prevent the progression to chronic chagasic cardiomyopathy. The therapeutic effects of compound 10 are promising and suggest a new possibility to treat this disease.

Asunto(s)

Enfermedad de Chagas/tratamiento farmacológico , Quinolinas/farmacología , Tripanocidas/farmacología , Trypanosoma cruzi/efectos de los fármacos , Animales , Supervivencia Celular/efectos de los fármacos , Enfermedad de Chagas/metabolismo , Chlorocebus aethiops , Relación Dosis-Respuesta a Droga , Femenino , Inflamación/tratamiento farmacológico , Inflamación/metabolismo , Ratones , Ratones Endogámicos C3H , Estructura Molecular , Pruebas de Sensibilidad Parasitaria , Quinolinas/síntesis química , Quinolinas/química , Relación Estructura-Actividad , Tripanocidas/síntesis química , Tripanocidas/química , Células Vero

RESUMEN

BACKGROUND: Drugs currently used for the treatment of Chagas' disease, nifurtimox and benznidazole, have a limited effectiveness and toxic side effects. With the aim of finding new therapeutic approaches, in vitro and in vivo anti-Trypanosoma cruzi activity of vitamin C alone and combined with benznidazole were investigated. METHODOLOGY/PRINCIPAL FINDINGS: The trypanocidal activity on epimastigote and trypomastigote forms was evaluated by counting parasites in a Neubauer chamber after treatment with the compounds. For the amastigote stage, transgenic parasites expressing ß-galactosidase were used and quantified by measuring the ß-galactosidase activity. The cytotoxicity of compounds was tested on Vero cells. The redox state of the parasite was evaluated by determining the reduced thiol levels (spectrophotometric assay) and the intracellular oxidative state (by flow cytometry). The in vivo trypanocidal activity was evaluated on a murine model of Chagas' disease. The trypanocidal activity of vitamin C and benznidazole was similar for the three parasite forms. When combining both drugs, vitamin C did not induce any change in the antiparasitic activity of benznidazole on trypomastigotes; however, on mammal cells, vitamin C diminished the cytotoxicity degree of benznidazole. Two mechanisms of action may be postulated for vitamin C: a lethal pro-oxidant effect on the parasite when used alone, and an antioxidant effect, when combined with benznidazole. A similar behavior was observed on infected mice; i.e., parasite counts in infected mice treated with vitamin C were lower than that of the control group. Animals treated with benznidazole presented lower parasitemia levels, as compared with those treated with vitamin C alone. Again, vitamin C did not cause any effect on the antiparasitic profile of benznidazole. Even though a combined treatment was employed, the antioxidant effect of vitamin C on the host was evidenced; a 100% survival was observed and the weight loss occurring during the acute phase of the infection was reduced. CONCLUSIONS/SIGNIFICANCE: Based on these results, the combination of vitamin C with benznidazole could be considered as an alternative treatment for Chagas' disease. These preliminary results encourage further research to improve the treatment of Chagas' disease.

Asunto(s)

Ácido Ascórbico/farmacología , Enfermedad de Chagas/tratamiento farmacológico , Interacciones Farmacológicas , Nitroimidazoles/farmacología , Tripanocidas/farmacología , Trypanosoma cruzi/efectos de los fármacos , Animales , Ácido Ascórbico/administración & dosificación , Peso Corporal , Enfermedad de Chagas/parasitología , Chlorocebus aethiops , Modelos Animales de Enfermedad , Quimioterapia Combinada/métodos , Femenino , Ratones Endogámicos C3H , Nitroimidazoles/administración & dosificación , Carga de Parásitos , Parasitemia , Análisis de Supervivencia , Resultado del Tratamiento , Tripanocidas/administración & dosificación , Células Vero

RESUMEN

BACKGROUND: Leishmaniasis and Chagas disease are life-threatening illnesses caused by the protozoan parasites Leishmania spp. and Trypanosoma cruzi, respectively. They are known as "neglected diseases" due to the lack of effective drug treatments and the scarcity of research work devoted to them. Therefore, the development of novel and effective drugs is an important and urgent need. Natural products are an important source of bioactive molecules for the development of new drugs. In this study, we evaluated the activity of enhydrin, uvedalin and polymatin B, three sesquiterpene lactones (STLs) isolated from Smallanthus sonchifolius, on Leishmania mexicana (MNYC/BZ/62/M) and Trypanosoma cruzi (Dm28c). In addition, the in vivo trypanocidal activity of enhydrin and uvedalin and the effects of these STLs on parasites' ultrastructure were evaluated. METHODS: The inhibitory effect of the three STLs on the growth of L. mexicana amastigotes and promastigotes as well as T. cruzi epimastigotes was evaluated in vitro. The changes produced by the STLs on the ultrastructure of parasites were examined by transmission electron microscopy (TEM). Enhydrin and uvedalin were also studied in a murine model of acute T. cruzi infection (RA strain). Serum activities of the hepatic enzymes alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase were used as biochemical markers of hepatotoxicity. RESULTS: The three compounds exhibited leishmanicidal activity on both parasite forms with IC50 values of 0.42-0.54 µg/ml for promastigotes and 0.85-1.64 µg/ml for intracellular amastigotes. Similar results were observed on T. cruzi epimastigotes (IC50 0.35-0.60 µg/ml). The TEM evaluation showed marked ultrastructural alterations, such as an intense vacuolization and mitochondrial swelling in both L. mexicana promastigotes and T. cruzi epimastigotes exposed to the STLs. In the in vivo study, enhydrin and uvedalin displayed a significant decrease in circulating parasites (50-71%) and no signs of hepatotoxicity were detected. CONCLUSIONS: Enhydrin, uvedalin and polymatin B possess significant leishmanicidal and trypanocidal activity on different parasite stages. These results show that these compounds may provide valuable leads for the development of new drugs against these neglected parasitic diseases.

Asunto(s)

Lactonas/farmacología , Leishmania mexicana/efectos de los fármacos , Sesquiterpenos de Germacrano/química , Sesquiterpenos/farmacología , Trypanosoma cruzi/efectos de los fármacos , Animales , Asteraceae/química , Enfermedad de Chagas/tratamiento farmacológico , Enfermedad de Chagas/parasitología , Modelos Animales de Enfermedad , Lactonas/administración & dosificación , Lactonas/efectos adversos , Lactonas/uso terapéutico , Leishmania mexicana/crecimiento & desarrollo , Leishmania mexicana/ultraestructura , Leishmaniasis/tratamiento farmacológico , Leishmaniasis/parasitología , Hígado/efectos de los fármacos , Ratones , Microscopía Electrónica de Transmisión , Extractos Vegetales/química , Extractos Vegetales/farmacología , Extractos Vegetales/uso terapéutico , Sesquiterpenos/administración & dosificación , Sesquiterpenos/efectos adversos , Sesquiterpenos/química , Sesquiterpenos/uso terapéutico , Sesquiterpenos de Germacrano/farmacología , Trypanosoma cruzi/crecimiento & desarrollo , Trypanosoma cruzi/ultraestructura

RESUMEN

In this work, the synthesis of a series of 2-arylazoimidazole derivatives 6-20 has been achieved through the reaction of imidazole with aryldiazonium salts, followed by ultrasound-assisted alkylation. This approach has important advantages including higher yield, shorter reaction times and milder reaction conditions. The structures of the compounds obtained were determined by MS, IR; and 1H and 13C NMR. The anti-Trypanosoma cruzi activity of the 15 compounds obtained was evaluated. Two compounds with piperidino substituents in the carboxamide moiety proved to be effective inhibitors of epimastigote proliferation, obtaining inhibition values comparable to those achieved with the reference drug Benznidazole. Besides, these compounds displayed low cytotoxicity on mammalian cells. In vivo, both compounds protected mice against a challenge with a lethal Trypanosoma cruzi strain. These results allow us to propose 2-arylazoimidazoles as lead compounds for the design of novel drugs to treat Chagas' disease.

Asunto(s)

Enfermedad de Chagas/tratamiento farmacológico , Imidazoles/química , Imidazoles/uso terapéutico , Tripanocidas/química , Tripanocidas/uso terapéutico , Trypanosoma cruzi/efectos de los fármacos , Alquilación , Animales , Línea Celular , Enfermedad de Chagas/parasitología , Humanos , Imidazoles/farmacología , Masculino , Ratones , Ratones Endogámicos BALB C , Sonicación , Tripanocidas/farmacología , Trypanosoma cruzi/citología

RESUMEN

Context Chagas' disease and leishmaniasis produce significant disability and mortality with great social and economic impact. The genus Stevia (Asteraceae) is a potential source of antiprotozoal compounds. Objective Aerial parts of four Stevia species were screened on Trypanosoma cruzi. Stevia satureiifolia (Lam.) Sch. Bip. var. satureiifolia (Asteraceae) dichloromethane extract was selected for a bioassay-guided fractionation in order to isolate its active compounds. Additionally, the antileishmanial activity and the cytotoxicity of these compounds on mammalian cells were assessed. Materials and methods The dichloromethane extract was fractionated by column chromatography. The isolated compounds were evaluated using concentrations of 0-100 µg/mL on T. cruzi epimastigotes and on Leishmania braziliensis promastigotes for 72 h, on trypomastigotes and amastigotes of T. cruzi for 24 h and 120 h, respectively. The compounds' cytotoxicity (12.5-500 µg/mL) was assessed on Vero cells by the MTT assay. The structure elucidation of each compound was performed by spectroscopic methods and HPLC analysis. Results The dichloromethane extracts of Stevia species showed significant activity on T. cruzi epimastigotes. The flavonoids eupatorin (1.3%), cirsimaritin (1.9%) and 5-desmethylsinensetin (1.5%) were isolated from S. satureiifolia var. satureiifolia extract. Eupatorin and 5-desmethylsinensetin showed IC50 values of 0.2 and 0.4 µg/mL on T. cruzi epimastigotes and 61.8 and 75.1 µg/mL on trypomastigotes, respectively. The flavonoid 5-desmethylsinensetin showed moderate activity against T. cruzi amastigotes (IC50 value = 78.7 µg/mL) and was the most active compound on L. braziliensis promastigotes (IC50 value = 37.0 µg/mL). Neither of the flavonoids showed cytotoxicity on Vero cells, up to a concentration of 500 µg/mL.

Asunto(s)

Leishmania braziliensis/efectos de los fármacos , Extractos Vegetales/farmacología , Stevia , Tripanocidas/farmacología , Trypanosoma cruzi/efectos de los fármacos , Animales , Supervivencia Celular/efectos de los fármacos , Fraccionamiento Químico , Chlorocebus aethiops , Cromatografía Líquida de Alta Presión , Relación Dosis-Respuesta a Droga , Concentración 50 Inhibidora , Leishmania braziliensis/crecimiento & desarrollo , Cloruro de Metileno/química , Pruebas de Sensibilidad Parasitaria , Fitoterapia , Componentes Aéreos de las Plantas , Extractos Vegetales/aislamiento & purificación , Extractos Vegetales/toxicidad , Plantas Medicinales , Solventes/química , Stevia/química , Tripanocidas/aislamiento & purificación , Tripanocidas/toxicidad , Trypanosoma cruzi/crecimiento & desarrollo , Células Vero

RESUMEN

Trypanosoma cruzi is the causative agent of Chagas' disease, which is a major endemic disease in Latin America and is recognized by the WHO as one of the 17 neglected tropical diseases in the world. Psilostachyin and psilostachyin C, two sesquiterpene lactones isolated from Ambrosia spp., have been demonstrated to have trypanocidal activity. Considering both the potential therapeutic targets present in the parasite, and the several mechanisms of action proposed for sesquiterpene lactones, the aim of this work was to characterize the mode of action of psilostachyin and psilostachyin C on Trypanosoma cruzi and to identify the possible targets for these molecules. Psilostachyin and psilostachyin C were isolated from Ambrosia tenuifolia and Ambrosia scabra, respectively. Interaction of sesquiterpene lactones with hemin, the induction of oxidative stress, the inhibition of cruzipain and trypanothione reductase and their ability to inhibit sterol biosynthesis were evaluated. The induction of cell death by apoptosis was also evaluated by analyzing phosphatidylserine exposure detected using annexin-V/propidium iodide, decreased mitochondrial membrane potential, assessed with Rhodamine 123 and nuclear DNA fragmentation evaluated by the TUNEL assay. Both STLs were capable of interacting with hemin. Psilostachyin increased about 5 times the generation of reactive oxygen species in Trypanosoma cruzi after a 4h treatment, unlike psilostachyin C which induced an increase in reactive oxygen species levels of only 1.5 times. Only psilostachyin C was able to inhibit the biosynthesis of ergosterol, causing an accumulation of squalene. Both sesquiterpene lactones induced parasite death by apoptosis. Upon evaluating the combination of both compounds, and additive trypanocidal effect was observed. Despite their structural similarity, both sesquiterpene lactones exerted their anti-T. cruzi activity through interaction with different targets. Psilostachyin accomplished its antiparasitic effect by interacting with hemin, while psilostachyin C interfered with sterol synthesis.

Asunto(s)

Enfermedad de Chagas/tratamiento farmacológico , Compuestos Heterocíclicos con 3 Anillos/farmacología , Lactonas/farmacología , Pironas/farmacología , Sesquiterpenos/farmacología , Trypanosoma cruzi/efectos de los fármacos , Ambrosia/química , Apoptosis/efectos de los fármacos , Enfermedad de Chagas/parasitología , Hemina/metabolismo , Compuestos Heterocíclicos con 3 Anillos/química , Compuestos Heterocíclicos con 3 Anillos/metabolismo , Humanos , Lactonas/química , Lactonas/metabolismo , Extractos Vegetales/química , Extractos Vegetales/farmacología , Pironas/química , Pironas/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Sesquiterpenos/química , Sesquiterpenos/metabolismo , Trypanosoma cruzi/patogenicidad

RESUMEN

Therapeutic vaccine research and development are especially important in Chagas disease considering the characteristics of the chronic infection and the number of people in the Americas living with a parasite infection for decades. We have previously reported the efficacy of attenuated Salmonella enterica (S) carrying plasmid encoding cruzipain (SCz) to protect against Trypanosoma cruzi infection. In the present work we investigated whether Cz DNA vaccine immunotherapy could be effective in controlling an ongoing T. cruzi infection in mice. We here report the intramuscular administration of naked Cz DNA or the oral administration of Salmonella as Cz DNA delivery system as therapeutic vaccines in mice during acute or chronic infection. The coadministration of a plasmid encoding GM-CSF improved vaccine performance, indicating that the stimulation of innate immune cells is needed in the event of an ongoing infection. These therapeutic vaccines were able to address the response to a protective and sustained Th1 biased profile not only against Cz but also against a variety of parasite antigens. The combined therapeutic vaccine during the chronic phase of infection prevents tissue pathology as shown by a reduced level of enzyme activity characteristic of tissue damage and a tissue status compatible with normal tissue. The obtained results suggest that immunotherapy with Cz and GM-CSF DNAs, either alone or in combination with other drug treatments, may represent a promising alternative for Chagas disease therapy.

Asunto(s)

Anticuerpos Antiprotozoarios/sangre , Enfermedad de Chagas/tratamiento farmacológico , Cisteína Endopeptidasas/uso terapéutico , ADN/uso terapéutico , Factor Estimulante de Colonias de Granulocitos y Macrófagos/genética , Inmunoterapia/métodos , Vacunas Antiprotozoos/inmunología , Trypanosoma cruzi/inmunología , Animales , Anticuerpos Antiprotozoarios/inmunología , Antígenos de Protozoos/inmunología , Enfermedad de Chagas/parasitología , Combinación de Medicamentos , Femenino , Inmunidad Innata/genética , Inmunidad Innata/inmunología , Inmunoglobulina G/sangre , Inmunoglobulina G/inmunología , Ratones , Ratones Endogámicos C3H , Parasitemia/tratamiento farmacológico , Parasitemia/prevención & control , Plásmidos/genética , Plásmidos/uso terapéutico , Proteínas Protozoarias , Salmonella/genética , Células TH1/inmunología , Trypanosoma cruzi/efectos de los fármacos , Vacunas de ADN/genética , Vacunas de ADN/inmunología

RESUMEN

The discovery of effective adjuvants for many vaccines especially those with limited commercial appeal, such as vaccines to poverty-related diseases, is required. In this work, we demonstrated that subcutaneous co-administration of mice with the outer membrane protein U-Omp19 from Brucella spp. plus OVA as antigen (Ag) increases Ag-specific T cell proliferation and T helper (Th) 1 immune responses in vitro and in vivo. U-Omp19 treated dendritic cells promote IFN-γ production by specific CD4(+) T cells and increases T cell proliferation. U-Omp19 co-administration induces the production of Ag specific effector memory T cell populations (CD4(+) CD44(high) CD62L(low) T cells). Finally, subcutaneous co-administration of U-Omp19 with Trypanosoma cruzi Ags confers protection against virulent parasite challenge, reducing parasitemia and weight loss while increasing mice survival. These results indicate that the bacterial protein U-Omp19 when delivered subcutaneously could be a suitable component of vaccine formulations against infectious diseases requiring Th1 immune responses.

Asunto(s)

Adyuvantes Inmunológicos/administración & dosificación , Antígenos Bacterianos/inmunología , Proteínas de la Membrana Bacteriana Externa/inmunología , Inmunidad Celular , Lipoproteínas/inmunología , Células TH1/inmunología , Animales , Anticuerpos Antibacterianos/sangre , Antígenos de Protozoos/inmunología , Brucella abortus , Bovinos , Células Cultivadas , Células Dendríticas/inmunología , Femenino , Memoria Inmunológica , Activación de Linfocitos , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ovalbúmina/administración & dosificación , Proteínas Recombinantes/inmunología , Trypanosoma cruzi

RESUMEN

We report here that a bacterial protease inhibitor from Brucella spp. called U-Omp19 behaves as an ideal constituent for a vaccine formulation against infectious diseases. When co-administered orally with an antigen (Ag), U-Omp19: i) can bypass the harsh environment of the gastrointestinal tract by inhibiting stomach and intestine proteases and consequently increases the half-life of the co-administered Ag at immune inductive sites: Peyer's patches and mesenteric lymph nodes while ii) it induces the recruitment and activation of antigen presenting cells (APCs) and increases the amount of intracellular Ag inside APCs. Therefore, mucosal as well as systemic Ag-specific immune responses, antibodies, Th1, Th17 and CD8(+) T cells are enhanced when U-Omp19 is co-administered with the Ag orally. Finally, this bacterial protease inhibitor in an oral vaccine formulation confers mucosal protection and reduces parasite loads after oral challenge with virulent Toxoplasma gondii.

Asunto(s)

Antígenos/metabolismo , Proteínas Bacterianas/farmacología , Brucella/química , Inmunidad Mucosa , Inhibidores de Proteasas/farmacología , Vacunas/inmunología , Administración Oral , Secuencia de Aminoácidos , Animales , Femenino , Ratones , Ratones Endogámicos , Datos de Secuencia Molecular

RESUMEN

Among the natural compounds, terpenoids play an important role in the drug discovery process for tropical diseases. The aim of the present work was to isolate antiprotozoal compounds from Ambrosia elatior and A. scabra. The sesquiterpene lactone (STL) cumanin was isolated from A. elatior whereas two other STLs, psilostachyin and cordilin, and one sterol glycoside, daucosterol, were isolated from A. scabra. Cumanin and cordilin were active against Trypanosoma cruzi epimastigotes showing 50% inhibition concentrations (IC50) values of 12 µM and 26 µM, respectively. Moreover, these compounds are active against bloodstream trypomastigotes, regardless of the T. cruzi strain tested. Psilostachyin and cumanin were also active against amastigote forms with IC50 values of 21 µM and 8 µM, respectively. By contrast, daucosterol showed moderate activity on epimastigotes and trypomastigotes and was inactive against amastigote forms. We also found that cumanin and psilostachyin exhibited an additive effect in their trypanocidal activity when these two drugs were tested together. Cumanin has leishmanicidal activity with growth inhibition values greater than 80% at a concentration of 5 µg/ml (19 µM), against both L. braziliensis and L. amazonensis promastigotes. In an in vivo model of T. cruzi infection, cumanin was more active than benznidazole, producing an 8-fold reduction in parasitemia levels during the acute phase of the infection compared with the control group, and more importantly, a reduction in mortality with 66% of the animals surviving, in comparison with 100% mortality in the control group. Cumanin also showed nontoxic effects at the doses assayed in vivo, as determined using markers of hepatic damage.

Asunto(s)

Ambrosia/química , Antiprotozoarios/aislamiento & purificación , Antiprotozoarios/farmacología , Leishmania/efectos de los fármacos , Terpenos/aislamiento & purificación , Terpenos/farmacología , Trypanosoma cruzi/efectos de los fármacos , Animales , Antiprotozoarios/administración & dosificación , Supervivencia Celular/efectos de los fármacos , Interacciones Farmacológicas , Concentración 50 Inhibidora , Masculino , Ratones , Ratones Endogámicos C3H , Parasitemia/tratamiento farmacológico , Parasitemia/parasitología , Terpenos/administración & dosificación

RESUMEN

Three thioamide-substituted imidazoquinolinone, which possess a heterocyclic center similar to tryptanthrin and are named C1, C2, and C3, were studied regarding (a) their in vitro anti-Trypanosoma cruzi activity, (b) their cytotoxicity and electrochemical behaviour, and (c) their effect on cell viability, redox state, and mitochondrial function. The assayed compounds showed a significant activity against the proliferative forms, but only C1 showed activity on the trypomastigote form (for C1, IC50 epi = 1.49 µM; IC50 amas = 1.74 µM; and IC50 try = 34.89 µM). The presence of an antioxidant compound such as ascorbic acid or dithiotreitol induced a threefold increase in the antiparasitic activity, whereas glutathione had a dual effect depending on its concentration. Our results indicate that these compounds, which exhibited low toxicity to the host cells, can be reduced inside the parasite by means of the pool of low molecular weight thiols, causing oxidative stress and parasite death by apoptosis. The antiparasitic activity of the compounds studied could be explained by a loss of the capacity of the antioxidant defense system of the parasite to keep its intracellular redox state. C1 could be considered a good candidate for in vivo evaluation.

RESUMEN

The aim of this study was to investigate the antiprotozoal and antiviral activities of four Argentinean Mikania species. The organic and aqueous extracts of Mikania micrantha, M. parodii, M. periplocifolia, and M. cordifolia were tested on Trypanosoma cruzi epimastigotes, Leishmania braziliensis promastigotes, and dengue virus type 2. The organic extract of M. micrantha was the most active against T. cruzi and L. braziliensis exhibiting a growth inhibition of 77.6 ± 4.5% and 84.9 ± 6.1%, respectively, at a concentration of 10 µg/ml. The bioguided fractionation of M. micrantha organic extract led to the identification of two active fractions. The chromatographic profile and infrared analysis of these fractions revealed the presence of sesquiterpene lactones. None of the tested extracts were active against dengue virus type 2.

Asunto(s)

Antiprotozoarios/farmacología , Antivirales/farmacología , Mikania/química , Extractos Vegetales/farmacología , Cromatografía Líquida de Alta Presión , Virus del Dengue/efectos de los fármacos , Técnicas In Vitro , Leishmania braziliensis/efectos de los fármacos , Espectroscopía Infrarroja por Transformada de Fourier , Trypanosoma cruzi/efectos de los fármacos

RESUMEN

A nutritional characteristic of trypanosomatid protozoa is that they need a heme compound as a growth factor. Because of the cytotoxic activity of heme and its structural similarity to cobalamins, we have investigated the in vitro and in vivo effect of vitamin B(12) (or cyanocobalamin) on the different forms of Trypanosoma cruzi. Cyanocobalamin showed a marked antiparasitic activity against epimastigotes (50% inhibitory concentration [IC(50)], 2.42 µM), amastigotes (IC(50), 10.69 µM), and trypomastigotes (IC(50), 9.46 µM). Anti-epimastigote and -trypomastigote values were 1.7 to 4 times lower than those obtained with the reference drug benznidazole (Bnz). We also found that B(12) and hemin do not interact with each other in their modes of action. Our results show that B(12) increases intracellular oxidative activity and stimulates both superoxide dismutase (50%) and ascorbate peroxidase (20%) activities, while the activity of trypanothione reductase was not modified. In addition, we found that the antioxidants dithiothreitol and ascorbic acid increase the susceptibility of the parasite to the cytotoxic action of B(12). We propose that vitamin B(12) exerts its growth-inhibitory effect through the generation of reactive oxygen species. In an in vivo assay, a significant reduction in the number of circulating parasites was found in T. cruzi-infected mice treated with cyanocobalamin and ascorbic acid. The reduction of parasitemia in benznidazole-treated mice was improved by the addition of these vitamins. According to our results, a combination of B(12) and Bnz should be further investigated due to its potential as a new therapeutic modality for the treatment of Chagas' disease.

Asunto(s)

Tripanocidas/farmacología , Tripanocidas/uso terapéutico , Trypanosoma cruzi/efectos de los fármacos , Vitamina B 12/farmacología , Vitamina B 12/uso terapéutico , Animales , Enfermedad de Chagas/tratamiento farmacológico , Enfermedad de Chagas/parasitología , Femenino , Masculino , Ratones , Nitroimidazoles/farmacología , Nitroimidazoles/uso terapéutico

RESUMEN

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

Asunto(s)

Antiprotozoarios/síntesis química , Antiprotozoarios/farmacología , Hidrazonas/síntesis química , Hidrazonas/farmacología , Trypanosoma cruzi/efectos de los fármacos , Animales , Antiprotozoarios/química , Antiprotozoarios/toxicidad , Técnicas de Química Sintética , Chlorocebus aethiops , Hidrazonas/química , Hidrazonas/toxicidad , Estadios del Ciclo de Vida/efectos de los fármacos , Esteroles/biosíntesis , Trypanosoma cruzi/crecimiento & desarrollo , Trypanosoma cruzi/metabolismo , Células Vero

RESUMEN

Research and development of new drugs effective in the treatment of Trypanosoma cruzi infections are a real need for the 16 million people infected in the Americas. In a previous work, a quinoline derivative substituted by a 2-piperidylmethyl moiety showed to be active against Chagas disease and was considered a lead compound for further optimization. A series of ten analogous derivatives were tested against epimastigotes as a first approach. In view of their promising results, six of them were evaluated against the blood and intracellular replicative forms of the parasite in humans. Among them, compound 12 which possesses a 6-acetamidohexylamino substituent showed remarkable improvement in activity against epimastigotes, trypomastigotes and amastigotes compared with the structure lead, as well as a good selectivity index for the two parasite stages present in humans. In addition, treatment of infected mice with compound 12 induced a significant reduction in parasitemia compared with non-treated mice. Molecular modeling studies were performed by computational methods in order to elucidate the factors determining these experimental bioactivities.

Asunto(s)

Quinolinas/síntesis química , Quinolinas/farmacología , Tripanocidas/síntesis química , Tripanocidas/farmacología , Espectroscopía de Resonancia Magnética , Modelos Moleculares , Quinolinas/química , Espectrofotometría Infrarroja , Tripanocidas/química

RESUMEN

Synthetic oligodeoxynucleotides containing unmethylated CpG motifs (CpG-ODN) have been characterized as Th1-promoting immunopotentiators, an adjuvant activity desirable for vaccination against intracellular parasites like Toxoplasma gondii. In an attempt to find new antigen-adjuvant combinations that enhance the immunogenicity of antigen candidates for toxoplasma vaccines, we analyzed the extent of protection in mice immunized with ROP2 and GRA4 recombinant proteins when co-administered with CpG-ODN. Both GRA4+CpG-ODN and ROP2+CpG-ODN formulations were shown to induce a strong humoral Th1-biased response characterized by a high IgG(2a) to IgG(1) antibody ratio. Both vaccination regimens led to increased secretion of IFN-γ and IL-10, and negligible amounts of IL-4, upon specific re-stimulation of spleen cells from these groups of mice. After a non-lethal challenge with tissue cysts of a moderately virulent strain, only the brains from mice vaccinated with ROP2 or GRA4 in combination with CpG-ODN showed a significant reduction (63% and 62%, respectively) in their parasite load compared to the controls. The rate of protection obtained with GRA4+ROP2+CpG-ODN resulted equivalent (66%) to those achieved with the single antigens plus CpG-ODN. Taken together, these results indicate that CpG-ODN is an important candidate adjuvant for use in potential multicomponent anti-T. gondii vaccines for animals and humans.

Asunto(s)

Proteínas de la Membrana/inmunología , Oligodesoxirribonucleótidos/inmunología , Proteínas Protozoarias/inmunología , Proteínas Recombinantes/inmunología , Toxoplasma/inmunología , Toxoplasmosis Animal/prevención & control , Adyuvantes Inmunológicos , Animales , Anticuerpos Antiprotozoarios/biosíntesis , Anticuerpos Antiprotozoarios/sangre , Encéfalo/parasitología , Citocinas/análisis , Femenino , Proteínas de la Membrana/genética , Ratones , Ratones Endogámicos C3H , Proteínas Protozoarias/genética , Vacunas Antiprotozoos/inmunología , Bazo/inmunología , Toxoplasmosis Animal/inmunología

RESUMEN

In this study, the antiprotozoal activity of the sesquiterpene lactone psilostachyin C was investigated. This natural compound was isolated from Ambrosia scabra by bioassay-guided fractionation and was identified by spectroscopic techniques. Psilostachyin C exerted in vitro trypanocidal activity against Trypanosoma cruzi epimastigotes, trypomastigotes and amastigotes, with 50% inhibitory concentration (IC(50)) values of 0.6, 3.5 and 0.9 µg/mL, respectively, and displayed less cytotoxicity against mammalian cells, with a 50% cytotoxic concentration (CC(50)) of 87.5 µg/mL. Interestingly, this compound induced ultrastructural alterations, as seen by transmission electron microscopy, in which vacuolisation and a structural appearance resembling multivesicular bodies were observed even at a concentration as low as 0.2 µg/mL. In an in vivo assay, a significant reduction in the number of circulating parasites was found in T. cruzi-infected mice treated with psilostachyin C for 5 days compared with untreated mice (7.4 ± 1.2 × 10(5)parasites/mL vs. 12.8 ± 2.0 × 10(5)parasites/mL) at the peak of parasitaemia. According to these results, psilostachyin C may be considered a promising template for the design of novel trypanocidal agents. In addition, psilostachyin C inhibited the growth of Leishmania mexicana and Leishmania amazonensis promastigotes (IC(50)=1.2 µg/mL and 1.5 µg/mL, respectively).

Asunto(s)

Antiprotozoarios/farmacología , Extractos Vegetales/farmacología , Sesquiterpenos/farmacología , Trypanosoma cruzi/efectos de los fármacos , Ambrosia/química , Animales , Antiprotozoarios/toxicidad , Línea Celular , Supervivencia Celular/efectos de los fármacos , Enfermedad de Chagas/tratamiento farmacológico , Modelos Animales de Enfermedad , Femenino , Humanos , Concentración 50 Inhibidora , Leishmania mexicana/efectos de los fármacos , Masculino , Ratones , Microscopía Electrónica de Transmisión , Extractos Vegetales/aislamiento & purificación , Extractos Vegetales/toxicidad , Enfermedades de los Roedores/tratamiento farmacológico , Sesquiterpenos/aislamiento & purificación , Sesquiterpenos/toxicidad , Resultado del Tratamiento , Trypanosoma cruzi/ultraestructura

RESUMEN

Despite the strong immune responses elicited after natural infection with Trypanosoma cruzi or vaccination against it, parasite survival suggests that these responses are insufficient or inherently inadequate. T. cruzi contains a major cystein proteinase, cruzipain, which has a catalytic N-terminal domain and a C-terminal extension. Immunizations that employed recombinant cruzipain or its N- and C-terminal domains allowed evaluation of the ability of cruzipain to circumvent responses against the catalytic domain. This phenomenon is not a property of the parasite but of cruzipain itself, because recombinant cruzipain triggers a response similar to that of cruzipain during natural or experimental infection. Cruzipain is not the only antigen with a highly immunogenic region of unknown function that somehow protects an essential domain for parasite survival. However, our studies show that this can be reverted by using the N-terminal domain as a tailored immunogen able to redirect host responses to provide enhanced protection.

Asunto(s)

Enfermedad de Chagas/prevención & control , Cisteína Endopeptidasas/inmunología , Vacunas Antiprotozoos/inmunología , Trypanosoma cruzi/genética , Animales , Anticuerpos Antiprotozoarios/sangre , Femenino , Ratones , Ratones Endogámicos C3H , Músculo Esquelético/patología , Miocardio/patología , Proteínas Protozoarias/inmunología , Proteínas Recombinantes/inmunología , Trypanosoma cruzi/enzimología , Trypanosoma cruzi/inmunología