Effect of N-alkyl and N-alkenyl substituents in noroxymorphindole, 17-substituted-6,7-dehydro-4,5alpha-epoxy-3,14-dihydroxy-6,7:2',3'-indolomorphinans, on opioid receptor affinity, selectivity, and efficacy.
The N-alkyl analogues (N-ethyl through N-heptyl), branched N-alkyl chain analogues (N-isopropyl, N-2-methylpropyl, and N-3-methylbutyl), and N-alkenyl analogues ((E)-N-3-methylallyl (crotyl), N-2-methylallyl, and N-3,3-dimethylallyl) were prepared in the noroxymorphindole series (17-substituted-6,7-dehydro-4,5alpha-epoxy-3,14-dihydroxy-6,7:2',3'-indolomorphinans), and the effect of the N-substituent on opioid receptor affinity, selectivity, and efficacy was examined using receptor binding assays, [(35)S]GTPgammaS efficacy determinations, and smooth muscle functional assays (electrically stimulated mouse vas deferens and guinea pig ileum). All of the compounds acted as opioid antagonists, including those with N-substituents which usually confer either weak agonist-antagonist behavior (N-ethyl) or potent opioid agonist activity (N-pentyl) in morphinan-like ligands which interact with the mu-receptor. Several N-substituted noroxymorphindoles were found to be more mu/delta-selective than naltrindole (NTI). The N-2-methylallylnoroxymorphindole, in particular, was found to be more selective than NTI in receptor binding assays (mu/delta = 1700 vs 120; kappa/delta = 810 vs 140), as an antagonist in the GTPgammaS assay (mu/delta = 170 vs 140; kappa/delta = 620 vs 160), and considerably more selective than NTI in the functional assays (mu/delta > 2200 vs 90). It also had high affinity for the delta-opioid receptor (K(i) = 4.7 nM in the binding assay) and high antagonist potency (1.2 nM in the GTPgammaS assay; 8.9 nM in the MVD assay).
McLamore
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S
Laboratory of Medicinal Chemistry, Building 8, Room B1-23, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0815, USA.
Ullrich
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T
Rothman
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RB
Xu
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H
Dersch
C
C
Coop
A
A
Davis
P
P
Porreca
F
F
Jacobson
A E
AE
Rice
K C
KC
D000818:Animals; D001667:Binding, Competitive; D004558:Electric Stimulation; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D009019:Morphinans / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D009292:Narcotic Antagonists; D011869:Radioligand Assay; D011957:Receptors, Opioid / Q000378:metabolism*; D017465:Receptors, Opioid, delta / Q000037:antagonists & inhibitors / Q000378:metabolism; D017473:Receptors, Opioid, kappa / Q000037:antagonists & inhibitors / Q000378:metabolism; D017450:Receptors, Opioid, mu / Q000037:antagonists & inhibitors / Q000378:metabolism; D013329:Structure-Activity Relationship; D014649:Vas Deferens / Q000187:drug effects / Q000502:physiology
C426027:17-(2-methyl-2-propenyl)-6,7-dehydro-4,5-epoxy-3,14-dihydroxy-6,7-2,3-indolomorphinan; D009019:Morphinans; D009292:Narcotic Antagonists; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D016244:Guanosine 5'-O-(3-Thiotriphosphate)