Discovery of a Potent (4 R,5 S)-4-Fluoro-5-methylproline Sulfonamide Transient Receptor Potential Ankyrin 1 Antagonist and Its Methylene Phosphate Prodrug Guided by Molecular Modeling

J Med Chem. 2018 Apr 26;61(8):3641-3659. doi: 10.1021/acs.jmedchem.8b00117. Epub 2018 Apr 12.

Abstract

Transient receptor potential ankyrin 1 (TRPA1) is a non-selective cation channel expressed in sensory neurons where it functions as an irritant sensor for a plethora of electrophilic compounds and is implicated in pain, itch, and respiratory disease. To study its function in various disease contexts, we sought to identify novel, potent, and selective small-molecule TRPA1 antagonists. Herein we describe the evolution of an N-isopropylglycine sulfonamide lead (1) to a novel and potent (4 R,5 S)-4-fluoro-5-methylproline sulfonamide series of inhibitors. Molecular modeling was utilized to derive low-energy three-dimensional conformations to guide ligand design. This effort led to compound 20, which possessed a balanced combination of potency and metabolic stability but poor solubility that ultimately limited in vivo exposure. To improve solubility and in vivo exposure, we developed methylene phosphate prodrug 22, which demonstrated superior oral exposure and robust in vivo target engagement in a rat model of AITC-induced pain.

MeSH terms

  • Animals
  • Dogs
  • Drug Discovery
  • Drug Stability
  • Humans
  • Ligands
  • Madin Darby Canine Kidney Cells
  • Microsomes, Liver / metabolism
  • Models, Molecular
  • Molecular Conformation
  • Prodrugs / chemical synthesis
  • Prodrugs / chemistry
  • Prodrugs / pharmacokinetics
  • Prodrugs / pharmacology*
  • Proline / analogs & derivatives*
  • Proline / chemical synthesis
  • Proline / pharmacokinetics
  • Proline / pharmacology*
  • Rats
  • Solubility
  • Structure-Activity Relationship
  • Sulfonamides / chemical synthesis
  • Sulfonamides / chemistry
  • Sulfonamides / pharmacokinetics
  • Sulfonamides / pharmacology*
  • TRPA1 Cation Channel / antagonists & inhibitors*
  • TRPA1 Cation Channel / chemistry

Substances

  • Ligands
  • Prodrugs
  • Sulfonamides
  • TRPA1 Cation Channel
  • TRPA1 protein, human
  • Trpa1 protein, rat
  • Proline