Antagonists of the adenosine A2A receptor based on a 2-arylbenzoxazole scaffold: Investigation of the C5- and C7-positions to enhance affinity

Eur J Med Chem. 2018 Jan 20:144:151-163. doi: 10.1016/j.ejmech.2017.12.007. Epub 2017 Dec 5.

Abstract

We have recently reported a series of 2-furoyl-benzoxazoles as potential A2A adenosine receptor (A2AR) antagonists. Two hits were identified with interesting pharmacokinetic properties but were find to bind the hA2AR receptor in the micromolar-range. Herein, in order to enhance affinity toward the hA2AR, we explored the C5- and C7-position of hits 1 and 2 based on docking studies. These modifications led to compounds with nanomolar-range affinity (e.g. 6a, Ki = 40 nM) and high antagonist activity (e.g. 6a, IC50 = 70.6 nM). Selected compounds also exhibited interesting in vitro DMPK (Drug Metabolism and Pharmacokinetics) properties including high solubility and low cytotoxicity. Therefore, the benzoxazole ring appears as a highly effective scaffold for the design of new A2A antagonists.

Keywords: A(2A) receptor; Benzoxazole; DMPK; Neurodegenerative disease.

MeSH terms

  • Adenosine A2 Receptor Antagonists / chemistry*
  • Adenosine A2 Receptor Antagonists / metabolism
  • Adenosine A2 Receptor Antagonists / pharmacokinetics
  • Adenosine A2 Receptor Antagonists / pharmacology*
  • Benzoxazoles / chemistry*
  • Benzoxazoles / metabolism
  • Benzoxazoles / pharmacokinetics
  • Benzoxazoles / pharmacology*
  • Caco-2 Cells
  • Cell Line, Tumor
  • Drug Design
  • Humans
  • Microsomes, Liver / metabolism
  • Receptor, Adenosine A2A / metabolism*
  • Solubility

Substances

  • Adenosine A2 Receptor Antagonists
  • Benzoxazoles
  • Receptor, Adenosine A2A