Benzoylbenzimidazole-based selective inhibitors targeting Cryptosporidium parvum and Toxoplasma gondii calcium-dependent protein kinase-1

Calcium-dependent protein kinase-1 (CDPK1) from Cryptosporidium parvum (CpCDPK1) and Toxoplasma gondii (TgCDPK1) have become attractive targets for discovering selective inhibitors to combat infections caused by these protozoa. We used structure-based design to improve a series of benzoylbenzimidazole-based compounds in terms of solubility, selectivity, and potency against CpCDPK1 and TgCDPK1. The best inhibitors show inhibitory potencies below 50 nM and selectivity well above 200-fold over two human kinases with small gatekeeper residues.