C-2-Linked Dimeric Strychnine Analogues as Bivalent Ligands Targeting Glycine Receptors

Research output: Contribution to journalJournal articlepeer-review

  • Darius P Zlotos
  • Carine M Abdelmalek
  • Liza S Botros
  • Maha M Banoub
  • Yasmine M Mandour
  • Ulrike Breitinger
  • Ahmed El Nady
  • Hans-Georg Breitinger
  • Christoph Sotriffer
  • Carmen Villmann
  • Jensen, Anders A.
  • Ulrike Holzgrabe

Strychnine is the prototypic antagonist of glycine receptors, a family of pentameric ligand-gated ion channels. Recent high-resolution structures of homomeric glycine receptors have confirmed the presence of five orthosteric binding sites located in the extracellular subunit interfaces of the receptor complex that are targeted by strychnine. Here, we report the synthesis and extensive pharmacological evaluation of bivalent ligands composed of two strychnine pharmacophores connected by appropriate spacers optimized toward simultaneous binding to two adjacent orthosteric sites of homomeric α1 glycine receptors. In all bivalent ligands, the two strychnine units were linked through C-2 by amide spacers of various lengths ranging from 6 to 69 atoms. Characterization of the compounds in two functional assays and in a radioligand binding assay indicated that compound 11a, with a spacer consisting of 57 atoms, may be capable of bridging the homomeric α1 GlyRs by simultaneous occupation of two adjacent strychnine-binding sites. The findings are supported by docking experiments to the crystal structure of the homomeric glycine receptor. Based on its unique binding mode, its relatively high binding affinity and antagonist potency, and its slow binding kinetics, the bivalent strychnine analogue 11a could be a valuable tool to study the functional properties of glycine receptors.

Original languageEnglish
JournalJournal of Natural Products
Volume84
Issue number2
Pages (from-to)382-394
ISSN0163-3864
DOIs
Publication statusPublished - 2021

ID: 257123612