Identification of (4-(9H-fluoren-9-yl) piperazin-1-yl) methanone derivatives as falcipain 2 inhibitors active against Plasmodium falciparum cultures.
Hernandez-Gonzalez, J. E., Salas-Sarduy, E., Hernandez Ramirez, L. F., Pascual, M. J., Alvarez, D. E., Pabon, A., Leite, V. B. P., Pascutti, P. G. and Valiente, P. A.
Departamento de Fisica, Universidade Estadual Paulista (UNESP), Sao Jose do Rio Preto, Sao Paulo CEP 15054-000, Brazil.; Computational Biology and Biomolecular Dynamics Laboratory, Center for Protein Studies, Faculty of Biology, University of Havana, Havana, Cuba.
Instituto de Investigaciones Biotecnologicas - Instituto Tecnologico de Chascomus (IIB-INTECH), Universidad Nacional de San Martin (UNSAM) - Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), San Martin, Buenos Aires, Argentina.
Grupo de Malaria, Facultad de Medicina, Universidad de Antioquia, Medellin, Colombia.
Departamento de Fisica, Universidade Estadual Paulista (UNESP), Sao Jose do Rio Preto, Sao Paulo CEP 15054-000, Brazil.
Laboratorio de Dinamica e Modelagem Molecular, Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Ave. Carlos Chagas Filho, 373, CCS-Bloco D sala 30, Cidade Universitaria Ilha de Fundao, Rio de Janeiro CEP 21941-902, Brazil.
Computational Biology and Biomolecular Dynamics Laboratory, Center for Protein Studies, Faculty of Biology, University of Havana, Havana, Cuba. Electronic address: valiente@fbio.uh.cu.
BACKGROUND: Falcipain 2 (FP-2) is the hemoglobin-degrading cysteine protease of Plasmodium falciparum most extensively targeted to develop novel antimalarials. However, no commercial antimalarial drugs based on FP-2 inhibition are available yet due to the low selectivity of most FP-2 inhibitors against the human cysteine proteases. METHODS: A structure-based virtual screening (SVBS) using Maybridge HitFinder compound database was conducted to identify potential FP-2 inhibitors. In vitro enzymatic and cell-growth inhibition assays were performed for the top-scoring compounds. Docking, molecular dynamics (MD) simulations and free energy calculations were employed to study the interaction of the best hits with FP-2 and other related enzymes. RESULTS AND CONCLUSIONS: Two hits based on 4-(9H-fluoren-9-yl) piperazin-1-yl) methanone scaffold, HTS07940 and HTS08262, were identified as inhibitors of FP-2 (half-maximal inhibitory concentration (IC50)=64muM and 14.7muM, respectively) without a detectable inhibition against the human off-target cathepsin K (hCatK). HTS07940 and HTS08262 inhibited the growth of the multidrug-resistant P. falciparum strain FCR3 in culture (half-maximal inhibitory concentrations (IC50)=2.91muM and 34muM, respectively) and exhibited only moderate cytotoxicity against HeLa cells (Half-maximal cytotoxic concentration (CC50)=133muM and 350muM, respectively). Free energy calculations reproduced the experimental affinities of the hits for FP-2 and explained the selectivity with respect to hCatK. GENERAL SIGNIFICANCE: To the best of our knowledge, HTS07940 stands among the most selective FP-2 inhibitors identified by SBVS reported so far, displaying moderate antiplasmodial activity and low cytotoxicity against human cells. Hence, this compound constitutes a promising lead for the design of more potent and selective FP-2 inhibitors.
Biochim Biophys Acta Gen Subj 1862(12): 2911-2923 (2018)