Structure-Activity Relationship Studies and Plasmodium Life Cycle Profiling Identifies Pan-Active N-Aryl-3-trifluoromethyl Pyrido[1,2- a]benzimidazoles Which Are Efficacious in an in Vivo Mouse Model of Malaria

J Med Chem. 2019 Jan 24;62(2):1022-1035. doi: 10.1021/acs.jmedchem.8b01769. Epub 2018 Dec 24.

Abstract

Structure-activity relationship studies involving N-aryl-3-trifluoromethyl pyrido[1,2- a]benzimidazoles (PBI) identified several compounds possessing potent in vitro activities against the asexual blood, liver, and gametocyte stages of the Plasmodium parasite with no cross-resistance to chloroquine. Frontrunner lead compounds with good in vitro absorption, distribution, metabolism, and excretion (ADME) profiles were subjected to in vivo proof-of-concept studies in NMRI mice harboring the rodent P. berghei infection. This led to the identification of compounds 10 and 49, effecting 98% and 99.93% reduction in parasitemia with mean survival days of 12 and 14, respectively, at an oral dose of 4 × 50 mg/kg. In vivo pharmacokinetics studies on 10 revealed slow absorption, low volume of distribution, and low clearance profiles. Furthermore, this series displayed a low propensity to inhibit the human ether-a-go-go-related gene (hERG) potassium ion channel whose inhibition is associated with cardiotoxicity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antimalarials / chemistry
  • Antimalarials / metabolism
  • Antimalarials / pharmacology
  • Antimalarials / therapeutic use*
  • Benzimidazoles / chemistry*
  • Benzimidazoles / metabolism
  • Benzimidazoles / pharmacology
  • Benzimidazoles / therapeutic use
  • Disease Models, Animal
  • Drug Design
  • ERG1 Potassium Channel / antagonists & inhibitors
  • ERG1 Potassium Channel / metabolism
  • Half-Life
  • Hemeproteins / antagonists & inhibitors
  • Hemeproteins / metabolism
  • Life Cycle Stages / drug effects
  • Malaria / drug therapy*
  • Malaria / mortality
  • Malaria / pathology
  • Mice
  • Mice, Inbred C57BL
  • Plasmodium / drug effects
  • Plasmodium / physiology*
  • Structure-Activity Relationship
  • Survival Rate

Substances

  • Antimalarials
  • Benzimidazoles
  • ERG1 Potassium Channel
  • Hemeproteins
  • KCNH2 protein, human
  • hemozoin