A series of 2,4-disubstituted quinolines as a new class of allosteric enhancers of the adenosine A3 receptor

J Med Chem. 2009 Feb 26;52(4):926-31. doi: 10.1021/jm8014052.


The adenosine receptor subfamily consists of the adenosine A(1), A(2A), A(2B), and A(3) receptors, which are localized in a variety of tissues throughout the human body. It is, therefore, a challenge to develop receptor specific ligands with improved tissue selectivity. Allosteric modulators could have these therapeutic advantages over orthosteric ligands. In the present study, a series of 2,4-disubstituted quinolines were synthesized on the basis of the structure of LUF6000 (34). Compound 27 (LUF6096) was able to allosterically enhance agonist binding to a similar extent as 34. In addition, this new compound showed low, if any, orthosteric affinity for any of the adenosine receptors. In a functional assay, compound 27 showed improved activity in comparison to 34, as it increased both the intrinsic efficacy and the potency of the reference agonist Cl-IB-MECA at the human adenosine A(3) receptor.

MeSH terms

  • Adenosine A3 Receptor Agonists*
  • Allosteric Regulation*
  • Aminoquinolines / chemistry
  • Humans
  • Imidazoles / chemistry
  • Ligands
  • Protein Binding
  • Quinolines / chemical synthesis*
  • Quinolines / pharmacology
  • Structure-Activity Relationship


  • Adenosine A3 Receptor Agonists
  • Aminoquinolines
  • Imidazoles
  • Ligands
  • N-(3,4-dichlorophenyl)-2-cyclohexyl-1H-imidazo(4,5-c)quinolin-4-amine
  • Quinolines