Synthesis and binding affinities of methylvesamicol analogs for the acetylcholine transporter and sigma receptor

Bioorg Med Chem. 2006 Apr 15;14(8):2620-6. doi: 10.1016/j.bmc.2005.11.044. Epub 2006 Jan 24.

Abstract

We synthesized methylvesamicol analogs 13-16 and investigated the binding characteristics of 2-[4-phenylpiperidino]cyclohexanol (vesamicol) and methylvesamicol analogs 13-16, with a methyl group introduced into the 4-phenylpiperidine moiety, to sigma receptors (sigma-1, sigma-2) and to vesicular acetylcholine transporters (VAChT) in membranes of the rat brain and liver. In competitive inhibition studies, (-)-o-methylvesamicol [(-)-OMV] (13) (Ki=6.7 nM), as well as (-)-vesamicol (Ki=4.4 nM), had a high affinity for VAChT. (+)-p-Methylvesamicol [(+)-PMV] (16) (Ki=3.0 nM), as well as SA4503 (Ki=4.4 nM), reported as a sigma-1 mapping agent for positron emission tomography (PET), had a high affinity for the sigma-1 receptor. The binding affinity of (+)-PMV (16) for the sigma-1 receptor (Ki=3.0 nM) was about 13 times higher than that for the sigma-2 (sigma-2) receptor (Ki=40.7 nM). (+)-PMV (16) (Ki=199 nM) had a much lower affinity for VAChT than SA4503 (Ki=50.2 nM) and haloperidol (Ki=41.4 nM). These results showed that the binding characteristics of (-)-OMV (13) to VAChT were similar to those of (-)-vesamicol and that (+)-PMV (16) bound to the sigma-1 receptor with high affinity. In conclusion, (-)-OMV (13) and (+)-PMV (16), which had a suitable structure, with a methyl group for labeling with 11C, may become not only a new VAChT ligand and a new type of sigma receptor ligand, respectively, but may also become a new target compound of VAChT and the sigma-1 receptor radioligand for PET, respectively.

MeSH terms

  • Animals
  • Brain / metabolism
  • Liver / metabolism
  • Magnetic Resonance Spectroscopy
  • Male
  • Piperidines / chemical synthesis*
  • Piperidines / metabolism*
  • Protein Binding
  • Radioligand Assay
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, sigma / metabolism*
  • Vesicular Acetylcholine Transport Proteins / metabolism*

Substances

  • Piperidines
  • Receptors, sigma
  • Vesicular Acetylcholine Transport Proteins
  • vesamicol