Tetrahydro-2-naphthyl and 2-Indanyl Triazolopyrimidines Targeting Plasmodium falciparum Dihydroorotate Dehydrogenase Display Potent and Selective Antimalarial Activity

J Med Chem. 2016 Jun 9;59(11):5416-31. doi: 10.1021/acs.jmedchem.6b00275. Epub 2016 May 21.

Abstract

Malaria persists as one of the most devastating global infectious diseases. The pyrimidine biosynthetic enzyme dihydroorotate dehydrogenase (DHODH) has been identified as a new malaria drug target, and a triazolopyrimidine-based DHODH inhibitor 1 (DSM265) is in clinical development. We sought to identify compounds with higher potency against Plasmodium DHODH while showing greater selectivity toward animal DHODHs. Herein we describe a series of novel triazolopyrimidines wherein the p-SF5-aniline was replaced with substituted 1,2,3,4-tetrahydro-2-naphthyl or 2-indanyl amines. These compounds showed strong species selectivity, and several highly potent tetrahydro-2-naphthyl derivatives were identified. Compounds with halogen substitutions displayed sustained plasma levels after oral dosing in rodents leading to efficacy in the P. falciparum SCID mouse malaria model. These data suggest that tetrahydro-2-naphthyl derivatives have the potential to be efficacious for the treatment of malaria, but due to higher metabolic clearance than 1, they most likely would need to be part of a multidose regimen.

MeSH terms

  • Animals
  • Antimalarials / chemical synthesis
  • Antimalarials / chemistry
  • Antimalarials / pharmacology*
  • Dihydroorotate Dehydrogenase
  • Disease Models, Animal
  • Dose-Response Relationship, Drug
  • Enzyme Inhibitors / chemical synthesis
  • Enzyme Inhibitors / chemistry
  • Enzyme Inhibitors / pharmacology*
  • Humans
  • Malaria, Falciparum / drug therapy*
  • Mice
  • Mice, SCID
  • Molecular Structure
  • Oxidoreductases Acting on CH-CH Group Donors / antagonists & inhibitors*
  • Oxidoreductases Acting on CH-CH Group Donors / metabolism
  • Parasitic Sensitivity Tests
  • Plasmodium falciparum / drug effects*
  • Plasmodium falciparum / enzymology
  • Pyrimidines / chemical synthesis
  • Pyrimidines / chemistry
  • Pyrimidines / pharmacology*
  • Rats
  • Structure-Activity Relationship
  • Triazoles / chemical synthesis
  • Triazoles / chemistry
  • Triazoles / pharmacology*

Substances

  • Antimalarials
  • Dihydroorotate Dehydrogenase
  • Enzyme Inhibitors
  • Pyrimidines
  • Triazoles
  • Oxidoreductases Acting on CH-CH Group Donors