Design and synthesis of new naphthalenic derivatives as ligands for 2-[125I]iodomelatonin binding sites

J Med Chem. 1995 Jun 9;38(12):2050-60. doi: 10.1021/jm00012a004.


New melatonin-like agents were designed from the frameworks of 2,5-dimethoxyphenethylamine, an important structural moiety for the 5-HT receptor, and (2-methoxynaphthyl)-ethylamine. The compounds were synthesized by classical methods and evaluated in binding assays with chicken brain membranes using 2-[125I]iodomelatonin as the radioligand. Preliminary studies on the series of N-acyl-disubstituted phenethylamines showed the favorable role of the methoxy group in the ortho position of the side chain on the affinity for the receptor (Ki = 8 +/- 0.2 nM) for N-[2-(2-methoxy-5-bromophenyl)ethyl]propionamide (3o). This effect was confirmed in a series of the naphthalene derivatives, a bioisosteric moiety of the indole ring, and several potent ligands for melatonin binding sites were prepared such as N-[2-(2-methoxynaphthyl)ethyl]propionamide (4b) (Ki = 0.67 +/- 0.05 nM) and N-[2-(2,7-dimethoxynaphthyl)ethyl]cyclopropylformamide (Ki = 0.05 +/- 0.004 nM) (4k). Structure-activity relationships are discussed with regard to melatonin and bioisosteric naphthalenic compound 2. The Ki value for 4b was affected to a similar extent to that of melatonin by GTP-gamma-S or Mn2+ in competition experiments, suggesting an agonist profile for this compound.

MeSH terms

  • Animals
  • Binding Sites
  • Chickens
  • Drug Design*
  • Iodine Radioisotopes / chemistry
  • Ligands
  • Magnetic Resonance Spectroscopy
  • Melatonin / chemistry
  • Melatonin / metabolism*
  • Naphthalenes / chemical synthesis*
  • Naphthalenes / chemistry
  • Naphthalenes / metabolism
  • Radioligand Assay
  • Structure-Activity Relationship


  • Iodine Radioisotopes
  • Ligands
  • Naphthalenes
  • Melatonin