Cascade Ligand- and Structure-Based Virtual Screening to Identify New Trypanocidal Compounds Inhibiting Putrescine Uptake.

Chagas disease is a neglected tropical disease endemic to Latin America, though migratory movements have recently spread it to other regions. Here, we have applied a cascade virtual screening campaign combining ligand- and structure-based methods. In order to find novel inhibitors of putrescine uptake in Trypanosoma cruzi, an ensemble of linear ligand-based classifiers obtained by has been applied as initial screening filter, followed by docking into a homology model of the putrescine permease TcPAT12. 1,000 individual linear classifiers were inferred from a balanced dataset. Subsequently, different schemes were tested to combine the individual classifiers: MIN operator, average ranking, average score, average voting, with MIN operator leading to the best performance. The homology model was based on the arginine/agmatine antiporter (AdiC) from Escherichia coli as template. It showed 64% coverage of the entire query sequence and it was selected based on the normalized Discrete Optimized Protein Energy parameter and the GA341 score. The modeled structure had 96% in the allowed area of Ramachandran's plot, and none of the residues located in non-allowed regions were involved in the active site of the transporter. Positivity Predictive Value surfaces were applied to optimize the score thresholds to be used in the ligand-based virtual screening step: for that purpose Positivity Predictive Value was charted as a function of putative yields of active in the range 0.001-0.010 and the Se/Sp ratio. With a focus on drug repositioning opportunities, DrugBank and Sweetlead databases were subjected to screening. Among 8 hits, cinnarizine, a drug frequently prescribed for motion sickness and balance disorder, was tested against T. cruzi epimastigotes and amastigotes, confirming its trypanocidal effects and its inhibitory effects on putrescine uptake. Furthermore, clofazimine, an antibiotic with already proven trypanocidal effects, also displayed inhibitory effects on putrescine uptake. Two other hits, meclizine and butoconazole, also displayed trypanocidal effects (in the case of meclizine, against both epimastigotes and amastigotes), without inhibiting putrescine uptake.

Inovação para tratamento da Doença de Chagas: efeito antiinflamatório e regulador do transito intestinal em ensaio pré clínico de dieta a base de subproduto vegetal / Inovation for treatment of Chagas disease: anti-inflammatory effect and regulator of intestinal transit in pre-clinical trial of diet to vegetable by products basis

A alimentação é básica para a saúde, auxiliando no enfrentamento de doenças, sendo os alimentos funcionais especialmente importantes nesse contexto. Alimentos funcionais são definidos como qualquer substância ou componente de um alimento que proporcione benefícios para a saúde, inclusive a prevenção e o tratamento de doenças. Os subprodutos alimentares provenientes da agroindústria possuem potencial para serem usados como alimentos funcionais, mas tal abordagem ainda é escassa, particularmente em aplicações em doenças negligenciadas. Considerando a facilidade de acesso a esses alimentos e seu baixocusto, o uso terapêutico desses subprodutos poderia se constituir como um complemento notratamento de doenças negligenciadas, como a doença de Chagas. A doença de Chagas éum importante problema de saúde pública na América Latina, sendo a forma digestiva asegunda principal manifestação dessa doença. O presente trabalho objetivou avaliar o efeitode uma dieta a base de subproduto com propriedade funcional (semente de abóbora) nainfecção experimental por T. cruzi com alteração intestinal, em associação ou não aotratamento com selênio. O subproduto foi avaliado quimicamente quanto à composiçãocentesimal, perfil lipídico, de minerais, de aminoácidos, atividade de água, capacidadeantioxidante e análise microbiológica. O ensaio pré-clinico foi realizado em camundongos,tendo sido analisados os seguintes parâmetros: parasitemia, peso corporal, consumo deração, trânsito intestinal e análise histopatológica. Os resultados mostraram que a sementede abóbora apresenta um alto teor de fibras, lipídios e proteínas, além de baixa atividade deágua e qualidade microbiológica, conforme legislação vigente para humanos. Inserida naração dos camundongos, comparativamente a rações normais, verificamos que no curso dainfecção em fase aguda não houve efeito na parasitemia dos animais infectados...

Food is essential for health and helps fighting diseases. Functional foods areespecially important in this context and are defined as any food substance orcomponent that provides health benefits, including disease prevention and treatment.Food sub-products derived from the agro-industry have the potential to be used asfunctional food. However, it is still incipient this approach, especially on neglecteddiseases. Taking into account the easy access to these foods and their low cost, thetherapeutic use of functional sub-products could complement the treatment ofneglected diseases, as Chagas disease. Chagas disease is an important publichealth problem in Latin America, and its gastro-intestinal form is the second mainmanifestation. This work aimed to evaluate the effect of a sub-product with functionalproperties (pumpkin seed-based diet) on the experimental infection with T. cruzi, amodel of intestinal dysfunction, associated or not to selenium treatment. The subproductwas chemically analyzed by determining its centesimal composition, lipid,amino acids and mineral profiles, water activity, anti-oxidant capacity, andmicrobiological analysis. A pre-clinic assay was done using mice and evaluating thefollowing parameters: parasitemia, body weight, food consume, intestinal transit andhistopathology...

Novel mitochondrial complex II isolated from Trypanosoma cruzi is composed of 12 peptides including a heterodimeric Ip subunit.

Mitochondrial respiratory enzymes play a central role in energy production in aerobic organisms. They differentiated from the alpha-proteobacteria-derived ancestors by adding noncatalytic subunits. An exception is Complex II (succinate: ubiquinone reductase), which is composed of four alpha-proteobacteria-derived catalytic subunits (SDH1-SDH4). Complex II often plays a pivotal role in adaptation of parasites in host organisms and would be a potential target for new drugs. We purified Complex II from the parasitic protist Trypanosoma cruzi and obtained the unexpected result that it consists of six hydrophilic (SDH1, SDH2N, SDH2C, and SDH5-SDH7) and six hydrophobic (SDH3, SDH4, and SDH8-SDH11) nucleus-encoded subunits. Orthologous genes for each subunit were identified in Trypanosoma brucei and Leishmania major. Notably, the iron-sulfur subunit was heterodimeric; SDH2N and SDH2C contain the plant-type ferredoxin domain in the N-terminal half and the bacterial ferredoxin domain in the C-terminal half, respectively. Catalytic subunits (SDH1, SDH2N plus SDH2C, SDH3, and SDH4) contain all key residues for binding of dicarboxylates and quinones, but the enzyme showed the lower affinity for both substrates and inhibitors than mammalian enzymes. In addition, the enzyme binds protoheme IX, but SDH3 lacks a ligand histidine. These unusual features are unique in the Trypanosomatida and make their Complex II a target for new chemotherapeutic agents.

Influence of dietary protein content on Trypanosoma cruzi infection in germfree and conventional mice

Camundongos isentos de germes (GF) e convencionais (CV) foram alimentados com racoes contendo 4,4, 13,2 ou 26,4 por cento de proteina nao ganharam peso durante quatro semanas, enquanto a racao deficiente em proteina nao afetou o crescimento dos camundongos GF. Apos quatro semanas nessas racoes, os camundongos foram inoculados com 5x10 elevado ao cubo tripomastigotos de Trypanosoma cruzi. A deficiencia em proteina afetou menos os camundongos GF do que os CV, segundo os seguintes parametros: ganho em peso, hemoglobina, niveis em proteina e albumina no plasma e conteudos em agua e proteina na carcassa. A infeccao com T. cruzi produziu um decrescimo significante nos niveis em hemoglobina, na contagem de celulas vermelhas sanguineas e nos conteudos em agua e proteina na carcaca. Este decrescimo foi mais acentuado nos camundongos GF...

El compromiso ocular en la enfermedad de Chagas congénita / Ocular involvement in congenital Chagas' disease

En 9 de 11 casos de enfermedad de Chagas congénita, se comprobó compromiso ocular. Las alteraciones fueron siempre del polo posterior del ojo: edema de la papila, pequeñas hemorragias retinales, coriorretinitis de aspecto variable, compromiso macular y opacidades vítreas prerretinales. Estas lesiones se presentaron aisladamente o combinándose en forma variable. El estudio histopatológico de uno de los niños, reveló infiltración linfoplasmocitaria de la coroides y de la retina. Las lesiones encontradas no fueron características . Aparentemente, la intesidad del daño ocular no se relaciona con el tiempo de evolución, ni con la severidad de los síntomas y signos clínicos. Estos niños tratados con Primaquina o con Nifurtimox, se observó mejoría en los exámenes fondoscópicos de control. Por la incidencia relativamente elevada del compromiso ocular en nuestros casos, recomendamos efectuar el estudio de fondo de ojos en todo niño en que se sospeche o se confirme una enfermedad de Chagas congénita

Fisiopatologia e aspectos dietoterápicos na Doença de Chagas

Aborda a fisiopatologia e os aspectos dietoterápicos na Doença de Chagas. Apresenta as características da Doença e descreve seus sintomas, etiologia, epidemiologia, diagnóstico e tratamento. Informa quais as zonas de propagação da Doença e como se dá o processo de infecção e aponta quais as populações mais suscetíveis a Doença. Aborda a Doença de Chagas em comorbidade com a Sífilis e o Bócio Endêmico. Enfoca as manifestações digestivas da Doença e apresenta propostas de três tipos de dietas para a mesma, sendo elas a dieta branda; a dieta líquida-pastosa; e a dieta exclusivamente liquída.