Characterization of 2,4-dianilinopyrimidines Against Five P. falciparum Kinases PfARK1, PfARK3, PfNEK3, PfPK9 and PfPKB

Plasmodium kinases are increasingly recognized as potential novel antiplasmodial targets for the treatment of malaria, but only a small subset of these kinases have had structure-activity-relationship (SAR) campaigns reported. Herein we report the discovery of CZC-54252 (1) as an inhibitor of five P. falciparum kinases PfARK1, PfARK3, PfNEK3, PfPK9 and PfPKB. 39 analogues were evaluated against all five kinases to establish SAR at three regions of the kinase active site. Nanomolar inhibitors of each kinase are discovered. We identify common and divergent SAR trends across all five kinases, highlighting substituents at each region that improve potency and selectivity for each kinase. Potent analogues were evaluated against the P. falciparum blood stage. Eight submicromolar inhibitors were discovered, of which 37 demonstrated potent antiplasmodial activity (EC50 = 0.16 μM). Our results provide an understanding of features needed to inhibit each individual kinase and lay groundwork for future optimization efforts towards novel antimalarials.