Design, synthesis and evaluation of a PLG tripeptidomimetic based on a pyridine scaffold

J Med Chem. 2004 Dec 16;47(26):6595-602. doi: 10.1021/jm049484q.

Abstract

A 2,3,4-substituted pyridine derivative has been identified as a potential tripeptidomimetic scaffold. The design of the scaffold was based on conformational and electrostatic comparisons with a natural tripeptide. The scaffold has been used in the synthesis of a Pro-Leu-Gly-NH2 (PLG) mimetic. The different substituents in the 2-, 3-, and 4-positions of the pyridine ring were introduced via an aromatic nucleophilic substitution reaction, a "halogen-dancing" reaction, and a Grignard coupling of a Boc-protected amino aldehyde, respectively. The synthetic route involves eight steps and provides the mimetic in 20% overall yield. The pyridine based PLG-mimetic was evaluated for its ability to enhance the maximum response of the dopamine agonist N-propylapomorphine (NPA) at human D2 receptors using a cell based assay (the R-SAT assay). The dose-response curve of the mimetic was found to exhibit a down-turn phase, similar to that of PLG. In addition, the mimetic was more potent than PLG to enhance the NPA response; the maximum response was found to be 146% at 10 nM concentration, as compared to 115% for PLG at the same concentration. Interestingly, conformational analysis by molecular modeling showed that the pyridine mimetic cannot adopt a type II beta-turn conformation that previously has been suggested to be the bioactive conformation of PLG.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetamides / chemical synthesis*
  • Acetamides / chemistry
  • Acetamides / pharmacology
  • Animals
  • Apomorphine / analogs & derivatives*
  • Apomorphine / pharmacology
  • Crystallography, X-Ray
  • Dopamine Agents / chemical synthesis*
  • Dopamine Agents / chemistry
  • Dopamine Agents / pharmacology
  • Drug Synergism
  • Humans
  • Hydrogen Bonding
  • MSH Release-Inhibiting Hormone / chemistry*
  • Mice
  • Models, Molecular
  • Molecular Mimicry
  • Molecular Structure
  • NIH 3T3 Cells
  • Protein Structure, Secondary
  • Pyridines / chemical synthesis*
  • Pyridines / chemistry
  • Pyridines / pharmacology
  • Receptors, Dopamine D2 / agonists
  • Structure-Activity Relationship

Substances

  • 2-(3-isobutyl-4-(pyrrolidine-2-carbonyl)pyridin-2-yloxy)acetamide
  • Acetamides
  • Dopamine Agents
  • Pyridines
  • Receptors, Dopamine D2
  • N-n-propylnorapomorphine
  • MSH Release-Inhibiting Hormone
  • Apomorphine