Ketanserin Analogues: Structure-Affinity Relationships for 5-HT2 and 5-HT1C Serotonin Receptor Binding

J Med Chem. 1992 Dec 25;35(26):4903-10. doi: 10.1021/jm00104a017.

Abstract

Ketanserin is the prototypic 5-HT2 serotonin antagonist; although it has been an important tool for the study of serotonin pharmacology, it has had relatively little impact on drug design because remarkably little is known about its structure-affinity relationships. Furthermore, ketanserin also binds at 5-HT1C receptors and even less is known about the influence of its structural features on 5-HT1C receptor affinity. The present study reveals that the fluoro and carbonyl groups of the 4-fluorobenzoyl portion of ketanserin make small contributions to 5-HT2 binding and that the intact benzoylpiperidine moiety is an important feature. Ring-opening of the piperidine ring reduces affinity. Although the quinazoline-2,4-dione moiety also contributes to binding, it appears to play a smaller role and can be structurally simplified with retention of 5-HT2 affinity. N-(4-Phenylbutyl)-4-(4-fluorobenzoyl)piperidine (39), for example, binds with nearly the same affinity (Ki = 5.3 nM) as ketanserin (Ki = 3.5 nM). All of the compounds examined bind at 5-HT1C sites with lower affinity than ketanserin, and some of the simplified analogues bind with nearly 10 times the 5-HT2 versus 5-HT1C selectivity of ketanserin; however, none displays > 120-fold selectivity. Several of the compounds, such as the amide 32 and the urea 33 represent examples of new structural classes of 5-HT2 ligands.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Binding, Competitive
  • Ketanserin / analogs & derivatives*
  • Ketanserin / metabolism
  • Male
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, Serotonin / drug effects*
  • Receptors, Serotonin / metabolism
  • Serotonin Antagonists / chemical synthesis*
  • Serotonin Antagonists / chemistry
  • Serotonin Antagonists / pharmacology
  • Structure-Activity Relationship

Substances

  • Receptors, Serotonin
  • Serotonin Antagonists
  • Ketanserin