RESUMO
The search for compounds with new structural scaffolds is an important tool to the discovery of new drugs against Chagas disease. We report herein the synthesis of 1,2,3-triazoles obtained from eugenol and di-hydroeugenol and their in vitro and in vivo trypanocidal activity. These derivatives were obtained by a three-step objective route and were suitably characterized by 1 H and 13 C nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry. Two compounds (9 and 10) showed activity against epimastigote forms of Trypanosoma cruzi (Y strain) in the range 42.8-88.4 µM and were weakly toxic to cardiomyoblast cells (H9c2 cells). The triazole 10 was the most active derivative and could reduce more than 50% of parasitemia after a 100-mg/kg oral treatment of mice infected with T. cruzi. Molecular docking studies suggested this compound could act as a trypanocidal agent by inhibiting cruzain, an essential enzyme for T. cruzi metabolism, usually inhibited by triazole compounds.
Assuntos
Doença de Chagas/tratamento farmacológico , Inibidores de Cisteína Proteinase/síntese química , Proteínas de Protozoários/antagonistas & inibidores , Triazóis/síntese química , Tripanossomicidas/síntese química , Trypanosoma cruzi/efeitos dos fármacos , Animais , Produtos Biológicos/química , Cisteína Endopeptidases , Inibidores de Cisteína Proteinase/farmacologia , Modelos Animais de Doenças , Desenho de Fármacos , Humanos , Camundongos , Simulação de Acoplamento Molecular , Estrutura Molecular , Relação Estrutura-Atividade , Triazóis/farmacologia , Tripanossomicidas/farmacologiaRESUMO
Chagas disease remains a major health problem in South America, and throughout the world. The two drugs clinically available for its treatment have limited efficacy and cause serious adverse effects. Cruzain is an established therapeutic target of Trypanosoma cruzi, the protozoan that causes Chagas disease. Our group recently identified a competitive cruzain inhibitor (compound 1) with an IC50 = 15 µM that is also more synthetically accessible than the previously reported lead, compound 2. Prior studies, however, did not propose a binding mode for compound 1, hindering understanding of the structure-activity relationship and optimization. Here, the cruzain binding mode of compound 1 was investigated using docking, molecular dynamics (MD) simulations with ab initio derived parameters, ab initio calculations, and MM/PBSA. Two ligand protonation states and four binding poses were evaluated. A careful ligand parameterization method was employed to derive more physically meaningful parameters than those obtained by automated tools. The poses of unprotonated 1 were unstable in MD, showing large conformational changes and diffusing away from the binding site, whereas the protonated form showed higher stability and interaction with negatively charged residues Asp161 and Cys25. MM/PBSA also suggested that these two residues contribute favorably to binding of compound 1. By combining results from MD, ab initio calculations, and MM/PBSA, a binding mode of 1 is proposed. The results also provide insights for further optimization of 1, an interesting lead compound for the development of new cruzain inhibitors.
Assuntos
Inibidores de Cisteína Proteinase/química , Modelos Moleculares , Proteínas de Protozoários/antagonistas & inibidores , Quinolinas/química , Cisteína Endopeptidases , Desenho de Fármacos , Ligantes , Estrutura Molecular , Ligação Proteica , Relação Estrutura-Atividade , TermodinâmicaRESUMO
BACKGROUND: Chagas' disease is one of the main causes of heart failure in developing countries. The disadvantages of current therapy include the undesirable side-effects, resistance, and therapeutic adhesion. The development of new efficient and safe drugs is, therefore, an issue of extreme importance. OBJECTIVES: In order to gain a better understanding of how the compounds interact with the target, computational methods are essential. METHODS: In this theoretical study, we report a docking protocol applied to a dataset of 173 cruzain inhibitors with IC50 values of less than 10 µM, belonging 16 different chemical classes. A preliminary analysis was performed, where the best protein structure for the study was identified. RESULTS: The enzyme was validated by redocking and a fingerprint graph for the ligand-enzyme interactions was generated, allowing the identification of the main amino acid residues related to the activity. Additionally, a larger cluster was generated, allowing the visualization of the orientation of the compounds and providing binding information for the different classes of compounds as well as their interaction in the cruzain active site. Amino acid residues other than those known as the catalytic triad (Gly23, Cys25, and Gly65) were identified, for example, Gln19 and Asp158. CONCLUSION: This provides a better insight into the mode of interaction of various cruzain inhibitors, which show IC50 values in the nanomolar range but which do not interact with the triad. These findings can help researchers to find new cruzain inhibitors for use in the fight against the Chagas disease.