Novel derivatives of 2-pyridinemethylamine as selective, potent, and orally active agonists at 5-HT(1A) receptors

Bernard Vacher, Bernard Bonnaud, Philippe Funes, Nathalie Jubault, Wouter Koek, Marie Bernadette Assié, Cristina Cosi, Mark Kleven

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Abstract

The aim of this work was to improve the oral bioavailability of a recently discovered, novel structural class of 5-HT(1A) receptor agonists: aryl-{[4-(6-R-pyridin-2-ylmethyl)-amino]-methyl}piperidin-1-yl-methanone. Incorporation of a fluorine atom in the β-position to the amino function in the side chain led to analogues that exhibited, in general, enhanced and long-lasting 5-HT(1A) agonist activity in rats after oral administration. Location of the fluorine atom at the C-4 position of the piperidine ring was the most favorable, and among the various substituents tested, the ability of the fluorine was unique in improving the oral activity of this family of ligands. Thus, the derivatives 39, 46, and 61 bound with higher affinity and selectivity to 5-HT(1A) receptors (versus dopaminergic D2 and adrenergic α1 receptors) and displayed more potent 5-HT(1A) agonist activity in vitro and in vivo than their C-4 desfluoro analogues. To examine the relationship between the conformation of the pharmacophore and the level of agonistic activity of this type of ligand, we synthesized a series of 3-chloro-4- fluorophenyl-(4-fluoro-4{[(5-(H or CH3)-6-R-pyridin-2-ylmethyl)-amino]- methyl}-piperidin-1-yl-methanone derivatives and found that the combination of a 5-methyl and a 6-methylamino substituent on the pyridine ring synergistically affected their 5-HT(1A) agonist properties. Thus, the 3- chloro-4-fluorophenyl-(4-fluoro-4{[(5-methyl-6-methylamino-pyridin-2- ylmethyl)-amino]-methyl}-piperidin-1-yl-methanone 40 behaved as a more potent 5-HT(1A) receptor agonist in vitro and in vivo than its 5- unsubstituted analogue 38. The antidepressant potential of the lead compounds 40, 45, and 54 was examined by means of the forced swimming test (FST) in rats. The results indicated that, after a single oral administration, these compounds inhibited immobility in the FST more potently and more extensively than the clinically used antidepressant imipramine. Thus, 40, 45, and 54 are potent, orally active 5-HT(1A) receptor agonists with marked antidepressant potential.

Original languageEnglish (US)
Pages (from-to)1648-1660
Number of pages13
JournalJournal of Medicinal Chemistry
Volume42
Issue number9
DOIs
StatePublished - May 6 1999

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ASJC Scopus subject areas

  • Molecular Medicine
  • Drug Discovery

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