title: Synthesis of an affinity ligand ('UPHIT') for in vivo acylation of the kappa-opioid receptor.
abstract: The isothiocyanate analog (1S,2S-trans-2-isothiocyanato-4,5-dichloro-N- methyl-N-[2-(1-pyrrolidinyl)cyclohexyl]benzeneacetamide, 3a) of the highly selective kappa-opioid receptor agonist, U50,488, was prepared as a potential site-directed affinity ligand for acylation of kappa-opioid receptors in vivo. The isothiocyanate (3a) which we have designated UPHIT and its enantiomer (3b) were synthesized in 3 steps starting from optically pure (1S,2S)-(+)-trans-2-pyrrolidinyl-N-methyl-cyclohexylamine (4a) and its enantiomer (4b), respectively, thus defining their absolute stereochemistry. Binding in vitro of the 1S,2S enantiomer 3a to kappa receptors labelled by [3H]U69,593 was shown to occur with an IC50 value of 25.92 +/- 0.36 nM, whereas 827.42 +/- 5.88 and 115.10 +/- 1.23 nM were obtained for the IC50 value of the 1R,2R enantiomer (3b) and (+/-)-3 respectively. Intracerebroventricular (ICV) injection of 100 micrograms of (+/-)-3 into guinea-pig brain followed by analysis of remaining kappa-binding sites 24 h later revealed that (+/-)-3 depleted 98% of the kappa receptors that bind [3H]U69,593 and 40% of those that bind [3H]bremazocine. These preliminary data suggest exciting uses for these compounds in furthering our knowledge of the kappa-opioid receptor.
authors.affiliation: Laboratory of Medicinal Chemistry, National Institute of Digestive, Diabetes, and Kidney Diseases, Bethesda, MD 20892.
authors.forename: B R
authors.initials: BR
authors.lastname: de Costa
authors.forename: L
authors.initials: L
authors.lastname: Band
authors.forename: R B
authors.initials: RB
authors.lastname: Rothman
authors.forename: A E
authors.initials: AE
authors.lastname: Jacobson
authors.forename: V
authors.initials: V
authors.lastname: Bykov
authors.forename: A
authors.initials: A
authors.lastname: Pert
authors.forename: K C
authors.initials: KC
authors.lastname: Rice
mesh_terms: D000215:Acylation; D000345:Affinity Labels / Q000138:chemical synthesis*; D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D006168:Guinea Pigs; D008297:Male; D011957:Receptors, Opioid / Q000378:metabolism*; D017473:Receptors, Opioid, kappa
chemical_list: D000345:Affinity Labels; D011957:Receptors, Opioid; D017473:Receptors, Opioid, kappa