Design of a new histamine H3 receptor antagonist chemotype: (3aR,6aR)-5-alkyl-1-aryl-octahydropyrrolo[3,4-b]pyrroles, synthesis, and structure-activity relationships

J Med Chem. 2009 Aug 13;52(15):4640-9. doi: 10.1021/jm900480x.

Abstract

A new histamine H3 receptor (H3R) antagonist chemotype 1 was designed by combining key pharmacophoric elements from two different precursor structural series and then simplifying and optimizing the resulting combined structural features. First, analogues were made based on a previously identified conessine-based H3R antagonist series. While the first analogues 11 and 15 showed no antagonistic activity to H3R, the mere addition of a key moiety found in the reference compound 7 (ABT-239) elevated the series to high potency at H3R. The hybrid structure (16b) was judged too synthetically demanding to enable an extensive SAR study, thus forcing a strategy to simplify the chemical structure. The resulting (3aR,6aR)-5-alkyl-1-aryl-octahydropyrrolo[3,4-b]pyrrole series proved to be highly potent, as exemplified by 17a having a human H3 K(i) of 0.54 nM, rat H3 K(i) of 4.57 nM, and excellent pharmacokinetics (PK) profile in rats (oral bioavailability of 39% and t(1/2) of 2.4 h).

MeSH terms

  • Animals
  • Drug Design
  • ERG1 Potassium Channel
  • Ether-A-Go-Go Potassium Channels / metabolism
  • Histamine H3 Antagonists / chemical synthesis*
  • Histamine H3 Antagonists / pharmacokinetics
  • Histamine H3 Antagonists / pharmacology
  • Humans
  • Pyrroles / chemical synthesis*
  • Pyrroles / pharmacokinetics
  • Pyrroles / pharmacology
  • Rats
  • Structure-Activity Relationship

Substances

  • ERG1 Potassium Channel
  • Ether-A-Go-Go Potassium Channels
  • Histamine H3 Antagonists
  • Pyrroles