Tambjamines as Fast-Acting Multistage Antimalarials.

Well-tolerated and novel antimalarials that can combat multiple stages of the parasite life cycle are desirable but challenging to discover and develop. Herein, we report results for natural product-inspired novel tambjamine antimalarials. We show that they are potent against liver, asexual erythrocytic, and sexual erythrocytic parasite life cycle stages. Notably, our lead candidate 1 (KAR425) displays excellent oral efficacy with complete clearance of parasites within 72 h of treatment in the humanized Plasmodium falciparum (NOD-scid) mouse model at 50 mg/kg × 4 days. Profiling of compound 1 demonstrated a fast in vitro killing profile. In addition, several other tambjamine analogues cured erythrocytic Plasmodium yoelii infections after oral doses of 30 and 50 mg/kg × 4 days in a murine model while exhibiting good safety and metabolic profiles. This study presents the first account of multiple-stage antiplasmodial activities with rapid killing profile in the tambjamine family.