Synthesis and biological properties of new constrained CCK-B antagonists: discrimination of two affinity states of the CCK-B receptor on transfected CHO cells

J Med Chem. 1997 Nov 21;40(24):3947-56. doi: 10.1021/jm970439a.


To improve our knowledge of the bioactive conformation of CCK-B antagonists, we have developed a new series of constrained dipeptoids whose synthesis and biochemical properties are reported here. These compounds, of general structure N alpha-[(2-adamantyloxy)carbonyl]-alpha-methyltryptophanyl-(4 -X)-proline, were designed by introducing a cyclization in the structure of the previously described CCK-B/peptoid antagonist RB 210, N-[N-[(2-adamantyloxy)carbonyl]-DL-alpha-methyltryptophanyl] -N-(2-phenylethyl)glycine (Blommaert et al. J. Med. Chem. 1993, 36, 2868-2877), by means of a five-membered ring. Structure-affinity relationship studies showed that an R configuration of Trp-C alpha and a cis configuration of the pyrrolidine substituents were favorable for receptor recognition. The most potent compounds of this new series had similar affinities for the CCK-B receptor as RB 210 and proved to be far more efficient in inhibiting inositol phosphate production in CHO cells stably transfected with rat brain CCK-B receptor, with IC50 values approaching those of the commonly used antagonists L-365,260 and PD-134,308. Moreover, binding studies performed using transfected CHO cells showed that two affinity states of the CCK-B receptor can be discriminated by some of these compounds which also have different biological profiles and are therefore highly interesting tools for the biochemical and pharmacological characterization of CCK-B receptor heterogeneity.

MeSH terms

  • Adamantane / analogs & derivatives*
  • Adamantane / chemical synthesis
  • Adamantane / pharmacology
  • Animals
  • CHO Cells / drug effects
  • CHO Cells / metabolism
  • CHO Cells / ultrastructure
  • Cricetinae
  • Dipeptides / chemical synthesis*
  • Dipeptides / pharmacology*
  • Guinea Pigs
  • Kinetics
  • Magnetic Resonance Spectroscopy
  • Peptoids
  • Proline / analogs & derivatives
  • Protein Conformation
  • Rats
  • Receptor, Cholecystokinin A
  • Receptor, Cholecystokinin B
  • Receptors, Cholecystokinin / antagonists & inhibitors*
  • Receptors, Cholecystokinin / chemistry
  • Receptors, Cholecystokinin / metabolism
  • Structure-Activity Relationship
  • Substrate Specificity
  • Transfection


  • Dipeptides
  • Peptoids
  • Receptor, Cholecystokinin A
  • Receptor, Cholecystokinin B
  • Receptors, Cholecystokinin
  • Proline
  • Adamantane