Structure-Activity Relationship Studies Reveal New Astemizole Analogues Active Against Plasmodium Falciparum In Vitro

In the context of drug repositioning and expanding the existing structure-activity relationship around astemizole (AST), a new series of analogues were designed, synthesized, and evaluated for their antiplasmodium activity. Among 46 analogues tested, compounds 21, 30, and 33 displayed high activities against asexual blood stage parasites (PfNFS4 IC50 = 0.025-0.043 mu M), whereas amide compound 46 additionally showed activity against late-stage gametocytes (stage IV/V; PfLG IC50 = 0.6 +/- 0.1 mu M) and 860-fold higher selectivity over hERG (46, SI = 43) compared to AST. Several analogues displaying high solubility (Sol > 100 mu M) and low cytoxicity in the Chinese hamster ovary (SI > 148) cell line have also been identified.