Discovery and Optimization of Thiazolidinyl and Pyrrolidinyl Derivatives as Inhaled PDE4 Inhibitors for Respiratory Diseases

J Med Chem. 2017 Dec 28;60(24):10026-10046. doi: 10.1021/acs.jmedchem.7b01044. Epub 2017 Dec 14.

Abstract

Phosphodiesterase 4 (PDE4) is a key cAMP-metabolizing enzyme involved in the pathogenesis of inflammatory disease, and its pharmacological inhibition has been shown to exert therapeutic efficacy in chronic obstructive pulmonary disease (COPD). Herein, we describe a drug discovery program aiming at the identification of novel classes of potent PDE4 inhibitors suitable for pulmonary administration. Starting from a previous series of benzoic acid esters, we explored the chemical space in the solvent-exposed region of the enzyme catalytic binding pocket. Extensive structural modifications led to the discovery of a number of heterocycloalkyl esters as potent in vitro PDE4 inhibitors. (S*,S**)-18e and (S*,S**)-22e, in particular, exhibited optimal in vitro ADME and pharmacokinetics properties and dose-dependently counteracted acute lung eosinophilia in an experimental animal model. The optimal biological profile as well as the excellent solid-state properties suggest that both compounds have the potential to be effective topical agents for treating respiratory inflammatory diseases.

MeSH terms

  • Administration, Inhalation
  • Animals
  • Binding Sites
  • Cyclic Nucleotide Phosphodiesterases, Type 4 / chemistry
  • Cyclic Nucleotide Phosphodiesterases, Type 4 / metabolism
  • Dose-Response Relationship, Drug
  • Drug Discovery
  • Drug Evaluation, Preclinical / methods
  • Drug Stability
  • Humans
  • Male
  • Phosphodiesterase 4 Inhibitors / administration & dosage
  • Phosphodiesterase 4 Inhibitors / chemistry*
  • Phosphodiesterase 4 Inhibitors / pharmacology*
  • Pulmonary Eosinophilia / drug therapy
  • Pyrrolidines / chemistry
  • Rats, Inbred BN
  • Respiratory Tract Diseases / drug therapy
  • Structure-Activity Relationship*
  • Thiazoles / chemistry

Substances

  • Phosphodiesterase 4 Inhibitors
  • Pyrrolidines
  • Thiazoles
  • Cyclic Nucleotide Phosphodiesterases, Type 4
  • pyrrolidine