Natural products and Chagas' disease: the action of triterpenes acids isolated from Miconia species / Productos naturales y mal de Chagas: la acción de los ácidos triterpenos aislados de especies de Miconia / Produtos naturais e doença de Chagas: a ação de triterpenos ácidos isolados de espécies de Miconia

The protozoan Trypanosoma cruzi causes Chagas' disease, a neglected illness that remains a relevant public health concern in Latin America. In Brazil, Benznidazole is available for its treatment. This compound is effective against circulating forms of the parasite in the acute phase of the disease, but its efficacy during the chronic stage is debatable. The search for new medications that can treat Chagas' disease is therefore mandatory. Natural sources display a wide range of secondary metabolites and may play an important role in the discovery of new potential drugs. Miconia is one of the largest genus of the family Melastomataceae and includes approximately 1,000 plant species; Brazil alone is home to approximately 250 of these species, which exist in forests and savannas. Studies on the various biological activities of the Miconia species have reported promising results. Several researchers have screened these plants as well as their extracts in vitro against trypomastigote forms of T. cruzi, which displayed significant trypanocidal activity. It has been demonstrated that the presence of ursolic and oleanolic determines this biological activity.

El protozoario Trypanosoma cruzi causa mal de Chagas, enfermedad que aún es problema de salud pública relevante en América Latina. El fármaco disponible en Brasil para el tratamiento es benznidazol. Este compuesto es eficaz contra la forma de circulación del parásito en la fase aguda de la enfermedad, pero su eficacia durante la fase crónica es discutible. Por lo tanto, la búsqueda de nuevos medicamentos que pueden tratar el mal de Chagas es necesaria. Las fuentes naturales presentan amplia gama de metabolitos secundarios y pueden desempeñar papel importante en el descubrimiento de nuevas drogas potenciales. Miconia es un género de los más grandes perteneciente a la familia Melatomateceae, incluyendo cerca de 1.000 especies de plantas; sólo en Brasil hay aproximadamente 250 de estas especies en florestas y sabanas. Los estudios sobre las diversas actividades biológicas de las especies Miconia han presentando resultados promisorios. Varios autores han evaluado extractos de estas plantas contra T. cruzi, comprobando que estos exiben actividad tripanocida significativa. La presencia de ácidos ursólico y oleanólico determinan la actividad biológica.

A doença de Chagas é uma doença negligenciada causada pelo protozoário Trypanosoma cruzi e ainda permanece como um relevante problema de saúde pública na América Latina. O medicamento disponível para o tratamento clínico no Brasil é o benzonidazol, que é efetivo contra as formas circulantes do parasita na fase aguda da doença, entretanto, sua eficácia na fase crónica permanece discutível. A pesquisa por novas drogas que possam ser utilizadas no tratamento dessa doença é urgentemente necessária e as fontes naturais com os seus metabólitos secundários diversificados, podem desempenhar um papel extremamente importante. Miconia é um dos maiores géneros pertencente à família Melastomataceae incluindo cerca de 1.000 espécies e, no Brasil existem cerca de 250 espécies em florestas e savanas. Estudos realizados com o objetivo de descrever as diferentes atividades biológicas de espécies de Miconia têm apresentado resultados promissores. Vários autores têm avaliado os extratos dessas plantas contra as formas tripomastigotas sanguíneas de T. cruzi (in vitro) e verificado que essas amostras exibem atvidade tripanocida significativa. A presença dos triterpenos ácidos ursólico oleanólico está relacionada com esta atividade biológica.

In vitro antiparasitic activity and chemical composition of the essential oil obtained from the fruits of Piper cubeba.

Protozoans of the trypanosomatid family cause the neglected tropical diseases leishmaniasis and trypanosomiasis, for which few drugs are available. In this context our group has recently reported that the essential oil obtained by steam distillation of the fruits of Piper cubeba is active against Schistosoma mansoni. Therefore, we have investigated the in vitro effects of the essential oil against the trypomastigote and amastigote forms of Trypanosoma cruzi isolated from an LLCMK2 cell line culture and the promastigote forms of Leishmania amazonensis. The in vitro activity of the essential oil against trypomastigotes of T. cruzi increased upon rising concentrations, giving IC50 values of 45.5 and 87.9 µg ·â€ŠmL⁻¹ against trypomastigotes and amastigotes, respectively. The essential oil was not active against L. amazonensis, since it displayed lyses of only 24 % at 400 µg ·â€ŠmL⁻¹, and an IC50 of 326.5 µg ·â€ŠmL⁻¹. Therefore, the essential oil should be further investigated to determine the compounds responsible for the observed activities, as well as its mechanism of action.

In vivo activity of ursolic and oleanolic acids during the acute phase of Trypanosoma cruzi infection.

Reduction in the parasitemic levels of the Y strain of Trypanosoma cruzi in mice treated with oral or intraperitoneal ursolic (UA) and oleanolic (OA) acids was evaluated during the acute phase of Chagas' disease. Oral administration of UA and OA (50mg/kg/day) provided the most significant reduction in the parasitemic peak, while intraperitoneal administration of UA and OA did not significantly affect the biological activity of the Y strain of T. cruzi. Interleukin levels in mice treated by the intraperitoneal route were compared to untreated chagasic mice. Reduced γ-IFN levels and enhanced IL-10 concentrations potentially explain the exacerbated parasitemia. Our data suggests an immunosuppressive effect for UA and OA, which could interfere with host control of parasitemia. Optimal results were achieved with oral administration. This observation may be explained by the low intestinal absorption of UA and OA, could cause a reduced immune response and promote parasite control. Taken together, these data demonstrate that triterpenes could be interesting compounds to develop therapeutically for the treatment of Chagas' disease.

Evaluation of the in vivo therapeutic properties of (-)-cubebin and (-)-hinokinin against Trypanosoma cruzi.

Even though the Chagas' disease, caused by the protozoan Trypanosoma cruzi, was described 100years ago by Carlos Chagas, it still represents a major public health concern and is found in 18 developing countries in South and Central America. In Brazil, Benznidazole (Rochagan) is the only drug with trypanocidal activity available in the market, despite its several side effects and limited efficacy in the chronic phase of the infection. In view of the need for new substances displaying biological activity against T. cruzi, there has been growing interest in research toward the attainment of compounds capable of acting on the parasite while being devoid of serious side effects. In this context, this study aims to evaluate the in vivo therapeutic activity of dibenzylbutyrolactone lignans (-)-cubebin and (-)-hinokinin during the acute phase of infection by T. cruzi. As a study criterion, animals with acute parasitemia were investigated by tissue morphometric analysis. There was significant parasitemia reduction in the groups of animals treated with (-)-cubebin or (-)-hinokin oral administration, compared to the negative control. Values close to those of the uninfected control were found in the groups treated with (-)-cubebin and (-)-hinokinin via kariometry, showing that there was positive cellular response compared to the infected control.

In vivo infection by Trypanosoma cruzi: a morphometric study of tissue changes in mice.

Nifurtimox and benznidazole, medications currently used for the treatment of the Chagas disease, are not always successful. We determine whether (-)-cubebin and (-)-hinokinin could be used as alternative drugs for the treatment of parasitic infections by Trypanosoma cruzi. To this end, male BALB/c mice were treated with both drugs, and the nuclear parameters (largest diameter, smallest diameter, and perimeter) were determined from slides prepared from the spleen, liver, and heart. The cytotoxicity of the substances was determined after 24-h treatment. Results revealed increased cell nuclei in untreated infected animals as compared to uninfected mice. The values obtained for infected animals treated with (-)-cubebin and (-)-hinokinin were close to those observed for uninfected mice. For the spleen, perimeter values of 10.85 µm (p < 0.01) and 10.90 µm (p < 0.05) were obtained for mice treated with (-)-cubebin 50 mg/kg and (-)-hinokinin 20 mg/kg, respectively, whereas untreated infected animals furnished a perimeter of 11.76 µm. As for the liver, perimeter values of 19.06 µm (p < 0.01) and 18.61 µm (p < 0.001) were achieved for mice treated with (-)-cubebin 50 mg/kg and (-)-hinokinin 20 mg/kg, respectively, whereas a perimeter of 18.54 µm was obtained for untreated infected animals. The cytotoxicity assays demonstrated that (-)-cubebin and (-)-hinokinin does not display toxicity. Therefore, (-)-cubebin and (-)-hinokinin are promising therapeutic agents and could be used in future clinical studies concerning treatment of the Chagas disease. Even if the karyometry is not used frequently, it can complement other methods, such as PCR, and furthermore, it is a simple method which is easily possible to analyze the activity of substances in the tissues of treated infected animals compared to uninfected animals.

Reduction of parasitism tissue by treatment of mice chronically infected with Trypanosoma cruzi with lignano lactones.

The reduction of parasitism tissue upon treatment with two lignano lactones, namely (-)- cubebin (CUB) and (-)-hinokinin (HNK), was evaluated in the chronic phase of Chagas' disease by quantifying the enzyme beta-galactosidase expressed by the CL B5 clone strain of Trypanosoma cruzi. Tissue karyometry was also performed. Treatment with the assessed lignans led to a larger reduction in parasitism tissue in all evaluated organs, compared with benznidazole (BZN). Oral treatment with CUB or HNK was more effective. Karyometry results demonstrated that the infected control animals had increased nuclear area compared with uninfected controls, indicating cellular hypertrophy. Results also revealed that use of CUB or HNK was able to significantly prevent this increase, and a slight decrease in the nuclear area was observed, compared with mice treated with BZN. Taken together, these data demonstrate that CUB and HNK could be considered as potential compounds for the development of new drugs for treatment of Chagas' disease.

New method for quantification of Trypanosoma cruzi in animal's tissue in the chronic phase of experimental Chagas' disease.

We developed a new method for the quantification of parasites in tissue. Trypanosoma cruzi strain CL parasites were genetically engineered to express the Escherichia coli beta-galactosidase gene, lacZ and this enzyme is able to catalyze a colorimetric reaction with chlorophenol red beta-D: galactopyranoside (CPRG) as the substrate. The animals were infected with clone CL Brener strain B5 of T. cruzi and treated with benznidazole in order to verify the reduction in the number of parasites in tissue study by quantifying the enzyme beta-galactosidase. The assay demonstrates a reduction in the number of parasites in the groups treated. Thus, this test can be used to test other substances with the aim of verifying the effectiveness in the chronic phase of experimental Chagas' disease.

(-)-Hinokinin-loaded poly(D,-lactide-co-glycolide) microparticles for Chagas disease.

The (-)-hinokinin display high activity against Trypanosoma cruzi in vitro and in vivo. (-)-Hinokinin-loaded poly(D,L-lactide-co-glycolide) microparticles were prepared and characterized in order to protect (-)-hinokinin of biological interactions and promote its sustained release for treatment of Chagas disease. The microparticles contain (-)-hinokinin were prepared by the classical method of the emulsion/solvent evaporation. The scanning electron microscopy, light-scattering analyzer were used to study the morphology and particle size, respectively. The encapsulation efficiency was determined, drug release studies were kinetically evaluated, and the trypanocidal effect was evaluated in vivo. (-)-Hinokinin-loaded microparticles obtained showed a mean diameter of 0.862 microm with smooth surface and spherical shape. The encapsulation efficiency was 72.46 +/- 2.92% and developed system maintained drug release with Higuchi kinetics. The preparation method showed to be suitable, since the morphological characteristics, encapsulation efficiency, and in vitro release profile were satisfactory. In vivo assays showed significant reduction of mice parasitaemia after administration of (-)-hinokinin-loaded microparticles. Thus, the developed microparticles seem to be a promising system for sustained release of (-)-hinokinin for treatment of Chagas disease.

In vitro trypanocidal activity of triterpenes from miconia species.

The bioassay-guided fractionation of methylene chloride extracts of Miconia fallax DC. and Miconia stenostachya DC. led to the isolation of five triterpene acids. The triterpenes ursolic acid, oleanolic acid and gypsogenic acid were active against blood trypomastigote forms of Trypanosoma cruzi. In contrast, the acetyl and methyl ester derivatives were not found to potentiate the trypanocidal activity. These results suggest the importance of the polar groups for activity.