Design, Synthesis, and Structure-Activity Relationship Studies of (4-Alkoxyphenyl)glycinamides and Bioisosteric 1,3,4-Oxadiazoles as GPR88 Agonists

J Med Chem. 2020 Dec 10;63(23):14989-15012. doi: 10.1021/acs.jmedchem.0c01581. Epub 2020 Nov 18.


Increasing evidence implicates the orphan G protein-coupled receptor 88 (GPR88) in a number of striatal-associated disorders. In this study, we report the design and synthesis of a series of novel (4-alkoxyphenyl)glycinamides (e.g., 31) and the corresponding 1,3,4-oxadiazole bioisosteres derived from the 2-AMPP scaffold (1) as GPR88 agonists. The 5-amino-1,3,4-oxadiazole derivatives (84, 88-90) had significantly improved potency and lower lipophilicity compared to 2-AMPP. Compound 84 had an EC50 of 59 nM in the GPR88 overexpressing cell-based cAMP assay. In addition, 84 had an EC50 of 942 nM in the [35S]GTPγS binding assay using mouse striatal membranes but was inactive in membranes from GPR88 knockout mice, even at a concentration of 100 μM. In vivo pharmacokinetic testing of 90 in rats revealed that the 5-amino-1,3,4-oxadiazole analogues may have limited brain permeability. Taken together, these results provide the basis for further optimization to develop a suitable agonist to probe GPR88 functions in the brain.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Drug Design
  • Glycine / analogs & derivatives*
  • Glycine / pharmacokinetics
  • Glycine / pharmacology*
  • Male
  • Mice, Knockout
  • Molecular Structure
  • Oxadiazoles / chemical synthesis
  • Oxadiazoles / pharmacokinetics
  • Oxadiazoles / pharmacology*
  • Rats, Long-Evans
  • Receptors, G-Protein-Coupled / agonists*
  • Solubility
  • Structure-Activity Relationship


  • Gpr88 protein, mouse
  • Gpr88 protein, rat
  • Oxadiazoles
  • Receptors, G-Protein-Coupled
  • Glycine