Design and synthesis of new naphthalenic derivatives as ligands for 2-[125I]iodomelatonin binding sites.
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.
Langlois
M
M
CNRS-BIOCIS, Faculté de Pharmacie, Châtenay-Malabry, France.
Brémont
B
B
Shen
S
S
Poncet
A
A
Andrieux
J
J
Sicsic
S
S
Serraz
I
I
Mathé-Allainmat
M
M
Renard
P
P
Delagrange
P
P
D000818:Animals; D001665:Binding Sites; D002645:Chickens; D015195:Drug Design; D007457:Iodine Radioisotopes / Q000737:chemistry; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008550:Melatonin / Q000737:chemistry / Q000378:metabolism*; D009281:Naphthalenes / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D011869:Radioligand Assay; D013329:Structure-Activity Relationship
D007457:Iodine Radioisotopes; D008024:Ligands; D009281:Naphthalenes; D008550:Melatonin