Evaluation of 4-Amino 2-Anilinoquinazolines against Plasmodium and Other Apicomplexan Parasites In Vitro and in a P. falciparum Humanized NOD-scid IL2Rγnull Mouse Model of Malaria

26 Feb 2019

Gilson PR, Nguyen W, Poole WA, Teixeira JE, Thompson JK, Guo K, Stewart RJ, Ashton TD, White KL, Sanz LM, Gamo FJ, Charman SA, Wittlin S, Duffy J, Tonkin CJ, Tham WH, Crabb BS, Cooke BM, Huston CD, Cowman AF, Sleebs BE

Antimicrobial Agents and Chemotherapy
PMID: 30559138

Doi: 10.1128/AAC.01804-18


A series of 4-amino 2-anilinoquinazolines optimized for activity against the most lethal malaria parasite of humans was evaluated for activity against other human parasites and related apicomplexans that infect humans and animals. Four of the most promising compounds from the 4-amino 2-anilinoquinazoline series were equally as effective against the asexual blood stages of the zoonotic, suggesting that they could also be effective against the closely related, another important human pathogen. The 2-anilinoquinazoline compounds were also potent against an array of parasites resistant to clinically available antimalarial compounds, although slightly less so than against the drug-sensitive 3D7 parasite line. The apicomplexan parasites were less sensitive to the 2-anilinoquinazoline series with a 50% effective concentration generally in the low micromolar range, suggesting that the yet to be discovered target of these compounds is absent or highly divergent in non- parasites. The 2-anilinoquinazoline compounds act as rapidly as chloroquine and when tested in rodents displayed a half-life that contributed to the compound's capacity to clear blood stages in a humanized mouse model. At a dose of 50 mg/kg of body weight, adverse effects to the humanized mice were noted, and evaluation against a panel of experimental high-risk off targets indicated some potential off-target activity. Further optimization of the 2-anilinoquinazoline antimalarial class will concentrate on improving efficacy and addressing adverse risk.

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