Tetrahydrofuran-Based Transient Receptor Potential Ankyrin 1 (TRPA1) Antagonists: Ligand-Based Discovery, Activity in a Rodent Asthma Model, and Mechanism-of-Action via Cryogenic Electron Microscopy

J Med Chem. 2021 Apr 8;64(7):3843-3869. doi: 10.1021/acs.jmedchem.0c02023. Epub 2021 Mar 22.

Abstract

Transient receptor potential ankyrin 1 (TRPA1) is a nonselective calcium-permeable ion channel highly expressed in the primary sensory neurons functioning as a polymodal sensor for exogenous and endogenous stimuli and has generated widespread interest as a target for inhibition due to its implication in neuropathic pain and respiratory disease. Herein, we describe the optimization of a series of potent, selective, and orally bioavailable TRPA1 small molecule antagonists, leading to the discovery of a novel tetrahydrofuran-based linker. Given the balance of physicochemical properties and strong in vivo target engagement in a rat AITC-induced pain assay, compound 20 was progressed into a guinea pig ovalbumin asthma model where it exhibited significant dose-dependent reduction of inflammatory response. Furthermore, the structure of the TRPA1 channel bound to compound 21 was determined via cryogenic electron microscopy to a resolution of 3 Å, revealing the binding site and mechanism of action for this class of antagonists.

MeSH terms

  • Animals
  • Asthma / chemically induced
  • Asthma / complications
  • Asthma / drug therapy*
  • CHO Cells
  • Cricetulus
  • Furans / chemical synthesis
  • Furans / metabolism
  • Furans / therapeutic use*
  • Guinea Pigs
  • Humans
  • Inflammation / drug therapy
  • Inflammation / etiology
  • Ligands
  • Male
  • Molecular Structure
  • Ovalbumin
  • Oxadiazoles / chemical synthesis
  • Oxadiazoles / metabolism
  • Oxadiazoles / therapeutic use
  • Protein Binding
  • Purines / chemical synthesis
  • Purines / metabolism
  • Purines / therapeutic use*
  • Rats
  • Rats, Sprague-Dawley
  • Structure-Activity Relationship
  • TRPA1 Cation Channel / antagonists & inhibitors*
  • TRPA1 Cation Channel / metabolism

Substances

  • Furans
  • Ligands
  • Oxadiazoles
  • Purines
  • TRPA1 Cation Channel
  • TRPA1 protein, human
  • Trpa1 protein, rat
  • Ovalbumin