Integração de métodos in silico e in vitro para o planejamento de inibidores da enzima cruzaína

• Autor(a) principal: Wiggers, Helton José
• Data de Publicação: 2011
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFSCAR
• Texto Completo: https://repositorio.ufscar.br/handle/ufscar/6201
• topic: Química orgânica; Chagas, Doença de; Química medicinal; Trypanosoma cruzi; Planejamento de substâncias bioativas; CIENCIAS EXATAS E DA TERRA::QUIMICA

Chagas disease, caused by the flagellate protozoan of the family Trypanosomatidae Trypanosoma cruzi, is endemic in Latin America. The available drugs are ineffective and cause severe side effects. Therefore, it is necessary the discovery and development of new drugs for Chagas disease chemotherapy. The cruzain enzyme (EC 3.4.22.51) is expressed in all T. cruzi life cycle and represents a valid target against Chagas disease. The search for new cruzain enzyme inhibitors was carried out through the development of a new strategy using in silico methods, based on integrated ligand and target virtual screening. The consensus of different virtual screenings allowed the selection of 23 molecules for in vitro assays, from a virtual library containing approximately 8.5 million structures collected from the commercial database ZINC. The compounds were assayed against the cruzain and human homologous cathepsin-L and 12 presented inhibitory activity. The IC50 values ranged from 5.6 to 73.9 μM for cruzain and 8.6 to 89.1 μM for cathepsin-L. The apparent inhibition constant (Ki app) of the identified compounds ranged from 3.7 and 64.5 μM for cruzaínain and 3.8 to 87.1 μM for the cathepsin-L and showed competitive inhibition mechanisms. New molecular classes of non-covalent inhibitors of the enzyme cruzain were identified. Two substances were validated as inhibitors by evaluating compound analogs to establishing relationships between molecular structure and biological activity; a substance with the ligand efficiency of 0.33 kcal mol-1 NA-1 was identified. Two enzyme inhibitors showed trypanocidal activity against the Y strain of T. cruzi trypomastigotes with potency comparable to the drug benznidazole®. The micromolar activity of the compounds against the cruzain enzyme and the confirmed activity against the parasite provide the opportunity for molecular optimization and improve the bioactive compounds design with known mode of action.