Potent and Selective Inhibitors of CDPK1 from T. gondii and C. parvum Based on a 5-Aminopyrazole-4-carboxamide Scaffold

5-Aminopyrazole-4-carboxamide was used as an alternative scaffold to substitute for the pyrazolopyrimidine of a known bumped kinase inhibitor to create selective inhibitors of calcium-dependent protein kinase-1 from both Toxoplasma gondii and Cryptosporidium parvum. Compounds with low nanomolar inhibitory potencies against the target enzymes were obtained. The most selective inhibitors also exhibited submicromolar activities in T. gondii cell proliferation assays and were shown to be nontoxic to mammalian cells.