Probes for narcotic receptor mediated phenomena. 17. Synthesis and evaluation of a series of trans-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)cyclohexyl]benzeneacet amide (U50,488) related isothiocyanate derivatives as opioid receptor affinity ligands.
A series of U50,488 related isothiocyanates was synthesized from enantiomerically pure (S,S)-(+)-trans-2-pyrrolidinyl-N-methylcyclohexylamine [(+)-7] and (R,R)-(-)-trans-2-pyrrolidinyl-N-methylcyclohexylamine [(-)-7]. DCC coupling of (+)- and (-)-7 with nitrophenylacetic acids followed by catalytic hydrogenation and treatment with thiophosgene afforded a series of six isomeric aryl isothiocyanate analogues of U50,488. Similarly, DCC coupling of (+)- and (-)-7 with (+)- and (-)-N-t-Boc-protected phenylglycines afforded four isomeric alkyl isothiocyanates. Evaluation of the isothiocyanates for their capacity to produce wash-resistant inhibition of mu, delta, and kappa sites in vitro was performed using rat and guinea pig brain membranes. None of the compounds was able to irreversibly inhibit binding of [3H]bremazocine to guinea pig and rat brain membranes (depleted of functional mu and delta receptors by pretreatment with acylating agents BIT and FIT). However, (1S,2S)-trans-2-isothiocyanato-N-methyl-N-[2- (1-pyrrolidinyl)cyclohexyl]benzeneacetamide [(-)-1] was able to specifically and irreversibly inhibit kappa receptors labeled by [3H]-U69,593: Incubation of rat brain membranes for 60 min at 25 degrees C with 1 microM of (-)-1 resulted in a wash-resistant reduction of the binding to 11.2 +/- 2.5% of the control. Binding analysis revealed the wash-resistant reduction in [3H]-U69,593 binding by (-)-1 to be through an increase in the Kd without effect on the Bmax. (-)-1 failed to effect mu or delta binding in rat or guinea pig brain under the same conditions. The enantiomer of (-)-1, (1R,2R)-trans-2-isothiocyanato-N-methyl-N-[2- (1-pyrrolidinyl)cyclohexyl]benzeneacetamide [(+)-1], failed to affect kappa receptors labeled by [3H]-U69,593 under the same conditions as for (-)-1. (1S,2S)-trans-3-Isothiocyanato-N-methyl-N-[2- (1-pyrrolidinyl)cyclohexyl]benzeneacetamide [(-)-2] inhibited to 49.6 +/- 5.1% of the control, in a wash-resistant manner, kappa receptors labeled by [3H]-U69,593. However, (-)-2 was not as selective as (-)-1 since it also reduced [3H]DADLE (delta) binding to 82.4 +/- 8.0% of the control value. (1S,2S)-trans-4-Isothiocyanato-N-methyl-N-[2-(1-pyrrolidinyl)- cyclohexyl]benzeneacetamide [(-)-3] exhibited selective wash-resistant inhibition of delta receptors labeled by [3H]DADLE resulting in a reduction in binding to 42.9 +/- 4.2% of control.(ABSTRACT TRUNCATED AT 400 WORDS)
de Costa
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Laboratory of Medicinal Chemistry, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892.
Rothman
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Bykov
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Band
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Pert
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Jacobson
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Rice
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D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D000700:Analgesics / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D044482:Benzeneacetamides; D001575:Benzomorphans / Q000378:metabolism; D001665:Binding Sites; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D055598:Chemical Phenomena; D002621:Chemistry; D003510:Cyclohexanes / Q000138:chemical synthesis* / Q000494:pharmacology; D006168:Guinea Pigs; D011759:Pyrrolidines / Q000138:chemical synthesis* / Q000378:metabolism / Q000494:pharmacology; D051381:Rats; D011957:Receptors, Opioid / Q000187:drug effects* / Q000378:metabolism; D017473:Receptors, Opioid, kappa; D013329:Structure-Activity Relationship; D013861:Thiocyanates / Q000138:chemical synthesis* / Q000494:pharmacology
D000700:Analgesics; D044482:Benzeneacetamides; D001575:Benzomorphans; D003510:Cyclohexanes; D011759:Pyrrolidines; D011957:Receptors, Opioid; D017473:Receptors, Opioid, kappa; D013861:Thiocyanates; C058445:2-isothiocyanato-N-methyl-N-(2-(1-pyrrolidinyl)cyclohexyl)benzeneacetamide; D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; C027248:bremazocine; C045444:U 69593