Reinvestigating Old Pharmacophores: Are 4-Aminoquinolines and Tetraoxanes Potential Two-Stage Antimalarials?

J Med Chem. 2016 Jan 14;59(1):264-81. doi: 10.1021/acs.jmedchem.5b01374. Epub 2015 Dec 18.

Abstract

The syntheses and antiplasmodial activities of various substituted aminoquinolines coupled to an adamantane carrier are described. The compounds exhibited pronounced in vitro and in vivo activity against Plasmodium berghei in the Thompson test. Tethering a fluorine atom to the aminoquinoline C(3) position afforded fluoroaminoquinolines that act as intrahepatocytic parasite inhibitors, with compound 25 having an IC50 = 0.31 μM and reducing the liver load in mice by up to 92% at 80 mg/kg dose. Screening our peroxides as inhibitors of liver stage infection revealed that the tetraoxane pharmacophore itself is also an excellent liver stage P. berghei inhibitor (78: IC50 = 0.33 μM). Up to 91% reduction of the parasite liver load in mice was achieved at 100 mg/kg. Examination of tetraoxane 78 against the transgenic 3D7 strain expressing luciferase under a gametocyte-specific promoter revealed its activity against stage IV-V Plasmodium falciparum gametocytes (IC50 = 1.16 ± 0.37 μM). To the best of our knowledge, compounds 25 and 78 are the first examples of either an 4-aminoquinoline or a tetraoxane liver stage inhibitors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aminoquinolines / chemical synthesis*
  • Aminoquinolines / metabolism
  • Aminoquinolines / pharmacology*
  • Animals
  • Antimalarials / chemical synthesis*
  • Antimalarials / metabolism
  • Antimalarials / pharmacology*
  • Drug Evaluation, Preclinical
  • Ether-A-Go-Go Potassium Channels / drug effects
  • Hemin / antagonists & inhibitors
  • Hepatocytes / metabolism
  • Humans
  • In Vitro Techniques
  • Liver / parasitology
  • Mice
  • Microsomes, Liver / metabolism
  • Parasite Load
  • Plasmodium berghei / drug effects
  • Plasmodium falciparum / drug effects
  • Structure-Activity Relationship
  • Tetraoxanes / chemical synthesis*
  • Tetraoxanes / metabolism
  • Tetraoxanes / pharmacology*

Substances

  • Aminoquinolines
  • Antimalarials
  • Ether-A-Go-Go Potassium Channels
  • Tetraoxanes
  • Hemin