RESUMO
The protozoan parasite Plasmodium falciparum causes the most severe form of human malaria and is estimated to kill 400,000 people a year. The parasite infects and replicates in host red blood cells (RBCs), where it expresses an array of proteases to carry out multiple essential processes. We are investigating the function of falcilysin (FLN), a protease known to be required for parasite development in the RBC. We previously developed a piperazine-based hydroxamic acid scaffold to generate the first inhibitors of FLN, and the current study reports the optimization of the lead compound from that series. A range of substituents were tested at the N1 and N4 positions of the piperazine core, and inhibitors with significantly improved potency against purified FLN and cultured P. falciparum were identified. Computational studies were also performed to understand the mode of binding for these compounds, and predicted a binding model consistent with the biochemical data and the distinctive SAR observed at both the N1 and N4 positions.
Assuntos
Antimaláricos/química , Ácidos Hidroxâmicos/química , Metaloendopeptidases/antagonistas & inibidores , Piperazina/química , Proteínas de Protozoários/antagonistas & inibidores , Antimaláricos/metabolismo , Antimaláricos/farmacologia , Sítios de Ligação , Ácidos Hidroxâmicos/metabolismo , Ácidos Hidroxâmicos/farmacologia , Metaloendopeptidases/metabolismo , Simulação de Acoplamento Molecular , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/metabolismo , Proteínas de Protozoários/metabolismo , Relação Estrutura-AtividadeRESUMO
The human parasite Plasmodium falciparum kills an estimated 445,000 people a year, with the most fatalities occurring in African children. Previous studies identified falcilysin (FLN) as a malarial metalloprotease essential for parasite development in the human host. Despite its essentiality, the biological roles of this protease are not well understood. Here we describe the optimization of a piperazine-based hydroxamic acid scaffold to develop the first reported inhibitors of FLN. Inhibitors were tested against cultured parasites, and parasiticidal activity correlated with potency against FLN. This suggests these compounds kill P. falciparum by blocking FLN, and that FLN is a druggable target. These compounds represent an important step towards validating FLN as a therapeutic target and towards the development of chemical tools to investigate the function of this protease.
