Discovery ofAmodiachins, a Novel Class of 4-AminoquinolineAntimalarials Active against Multidrug-Resistant <i>Plasmodium falciparum</i>

Abstract A structure activity relationship study was conducted to optimize metabolic stability and in vivo activity of amodiaquine analog antimalarials. Antiplasmodial activity of synthesized amodiachins (ADCs) were evaluated against drug-sensitive and drug-resistant strains of Plasmodium falciparum. Select compounds were tested in Plasmodium yoelli murine models. Structural modifications, including introduction of a piperidine ring and varied N-alkyl substitutions enhanced antiparasitic activity, metabolic stability, and in vivo efficacy. Compound 43 (ADC-028) emerged as a standout candidate, exhibiting nanomolar activity against drug-sensitive and multidrug-resistant P. falciparum, minimal cytotoxicity, and favorable murine microsomal stability (t1/2 = 48.2 min). In vivo, 43 achieved a nonrecrudescence dose at 16 mg/kg/d and a single dose cure at 50 mg/kg. Pharmacokinetic analysis of 43 showed excellent metabolic stability (T1/2 = 84 h) and oral bioavailability (F = 76%). This study identifies 43 as a potential candidate for further evaluation as a novel compound to overcome drug-resistant malaria.