16-Bromoepiandrosterone, an activator of the mammalian immune system, inhibits glucose 6-phosphate dehydrogenase from Trypanosoma cruzi and is toxic to these parasites grown in culture

Autor(es)

Cordeiro, Artur T. ^[1] ; Thiemann, Otavio H. ^[2]

Afiliação do(s) autor(es)

^[1] Ctr Pesquisa Energia & Mat, Lab Nacl Biociencias, BR-10000 Campinas, SP - Brazil

^[2] Univ Sao Paulo, Inst Fis Sao Carlos, Ctr Biol Mol Estrutural, Sao Carlos, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Bioorganic & Medicinal Chemistry; v. 18, n. 13, p. 4762-4768, JUL 1 2010.
• Citações Web of Science: 18

Resumo

Glucose 6-phosphate dehydrogenase (G6PDH) catalyzes the first step of the pentose-phosphate pathway which supplies cells with ribose 5-phosphate (R5P) and NADPH. R5P is the precursor for the biosynthesis of nucleotides while NADPH is the cofactor of several dehydrogenases acting in a broad range of biosynthetic processes and in the maintenance of the cellular redox state. RNA interference-mediated reduction of G6PDH levels in bloodstream-form Trypanosoma brucei validated this enzyme as a drug target against Human African Trypanosomiasis. Dehydroepiandrosterone (DHEA), a human steroidal pro-hormone and its derivative 16 alpha-bromoepiandrosterone (16BrEA) are uncompetitive inhibitors of mammalian G6PDH. Such steroids are also known to enhance the immune response in a broad range of animal infection models. It is noteworthy that the administration of DHEA to rats infected by Trypanosoma cruzi, the causative agent of Human American Trypanosomiasis (also known as Chagas' disease), reduces blood parasite levels at both acute and chronic infection stages. In the present work, we investigated the in vitro effect of DHEA derivatives on the proliferation of T. cruzi epimastigotes and their inhibitory effect on a recombinant form of the parasite's G6PDH (TcG6PDH). Our results show that DHEA and its derivative epiandrosterone (EA) are uncompetitive inhibitors of TcG6PDH, with K(i) values of 21.5 +/- 0.5 and 4.8 +/- 0.3 mu M, respectively. Results from quantitative inhibition assays indicate 16BrEA as a potent inhibitor of TcG6PDH with an IC(50) of 86 +/- 8 nM and those from in vitro cell viability assays confirm its toxicity for T. cruzi epimastigotes, with a LD(50) of 12 +/- 8 mu M. In summary, we demonstrated that, in addition to host immune response enhancement, 16BrEA has a direct effect on parasite viability, most likely as a consequence of TcG6PDH inhibition. Crown Copyright (C) 2010 Published by Elsevier Ltd. All rights reserved. (AU)

• Processo FAPESP: 05/51966-6 - Emprego de ensaios de HTS na identificação de compostos guia de produtos naturais e abordagens de planejamento racional de fármacos a alvos selecionados de doenças parasitárias
• Beneficiário: Otavio Henrique Thiemann
• Modalidade de apoio: Auxílio à Pesquisa - Programa BIOTA - Regular
• Processo FAPESP: 98/14138-2 - Center for Structural Molecular Biotechnology
• Beneficiário: Glaucius Oliva
• Modalidade de apoio: Auxílio à Pesquisa - Centros de Pesquisa, Inovação e Difusão - CEPIDs
• Processo FAPESP: 07/02663-6 - Caracterizacao estrutural das enzimas de trypanosomatideos que atuam sobre a primeira etapa da via glicolitica e da via de pentoses.
• Beneficiário: Artur Torres Cordeiro
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado