RESUMEN
The protein kinase PfCLK3 plays a critical role in the regulation of malarial parasite RNA splicing and is essential for the survival of blood stage Plasmodium falciparum. We recently validated PfCLK3 as a drug target in malaria that offers prophylactic, transmission blocking, and curative potential. Herein, we describe the synthesis of our initial hit TCMDC-135051 (1) and efforts to establish a structure-activity relationship with a 7-azaindole-based series. A total of 14 analogues were assessed in a time-resolved fluorescence energy transfer assay against the full-length recombinant protein kinase PfCLK3, and 11 analogues were further assessed in asexual 3D7 (chloroquine-sensitive) strains of P. falciparum parasites. SAR relating to rings A and B was established. These data together with analysis of activity against parasites collected from patients in the field suggest that TCMDC-135051 (1) is a promising lead compound for the development of new antimalarials with a novel mechanism of action targeting PfCLK3.
Asunto(s)
Antimaláricos/farmacología , Diseño de Fármacos , Plasmodium falciparum/enzimología , Inhibidores de Proteínas Quinasas/farmacología , Proteínas Serina-Treonina Quinasas/antagonistas & inhibidores , Proteínas Tirosina Quinasas/antagonistas & inhibidores , Antimaláricos/síntesis química , Antimaláricos/química , Modelos Moleculares , Plasmodium falciparum/efectos de los fármacos , Conformación Proteica , Inhibidores de Proteínas Quinasas/síntesis química , Inhibidores de Proteínas Quinasas/química , Proteínas Serina-Treonina Quinasas/química , Proteínas Tirosina Quinasas/química , Relación Estructura-ActividadRESUMEN
The requirement for next-generation antimalarials to be both curative and transmission-blocking necessitates the identification of previously undiscovered druggable molecular pathways. We identified a selective inhibitor of the Plasmodium falciparum protein kinase PfCLK3, which we used in combination with chemogenetics to validate PfCLK3 as a drug target acting at multiple parasite life stages. Consistent with a role for PfCLK3 in RNA splicing, inhibition resulted in the down-regulation of more than 400 essential parasite genes. Inhibition of PfCLK3 mediated rapid killing of asexual liver- and blood-stage P. falciparum and blockade of gametocyte development, thereby preventing transmission, and also showed parasiticidal activity against P. berghei and P. knowlesi Hence, our data establish PfCLK3 as a target for drugs, with the potential to offer a cure-to be prophylactic and transmission blocking in malaria.