Rapid triaging of three series of related hits selected from the Tres Cantos Anti-Malarial Set (TCAMS) are described. A triazolopyrimidine series was deprioritized due to delayed inhibition of parasite growth. A lactic acid series has derivatives with IC50 < 500 nM in a standard Plasmodium falciparum in vitro whole cell assay (Pf assay) but shows half-lives of < 30 min in both human and murine microsomes. Compound 19, from a series of cyclopropyl carboxamides, is a highly potent in vitro inhibitor of P. falciparum (IC50 = 3 nM) and has an oral bioavailability of 55% in CD-1 mice and an ED90 of 20 mg/kg after oral dosing in a nonmyelo-depleted P. falciparum murine model.
Keywords: Medicines for Malaria Venture; Plasmodium falciparum; TCAMS; Tres Cantos Anti-Malarial Set; carboxamide; cyclopropyl; in vivo activity; malaria; murine; oral bioavailability; triazole.