title: Synthesis and Pharmacology of the enantiomers of the potential atypical antipsychotic agents 5-OMe-BPAT and 5-OMe-(2,6-di-OMe)-BPAT.
abstract: The optically pure enantiomers of the potential atypical antipsychotic agents 5-methoxy-2-[N-(2-benzamidoethyl)-N-n-propylamino]tetralin (5-OMe-BPAT, 5) and 5-methoxy-2-{N-[2-(2,6-dimethoxy)benzamidoethyl]-N-n-propylamino}t etralin [5-OMe-(2,6-di-OMe)-BPAT, 6] were synthesized and evaluated for their in vitro binding affinities at alpha1-, alpha2-, and beta-adrenergic, muscarinic, dopamine D1, D2A, and D3, and serotonin 5-HT1A and 5-HT2 receptors. In addition, their intrinsic efficacies at serotonin 5-HT1A receptors were established in vitro. (S)- and (R)-5 had high affinities for dopamine D2A, D3, and serotonin 5-HT1A receptors, moderate affinities for alpha1-adrenergic and serotonin 5-HT2 receptors, and no affinity (Ki > 1000 nM) for the other receptor subtypes. (S)- and (R)-6 had lower affinities for the dopamine D2A and the serotonin 5-HT1A receptor, compared to (S)- and (R)-5, and hence showed some selectivity for the dopamine D3 receptor. The interactions with the receptors were stereospecific, since the serotonin 5-HT1A receptor preferred the (S)-enantiomers, while the dopamine D2A and D3 receptors preferred the (R)-enantiomers of 5 and 6. The intrinsic efficacies at the serotonin 5-HT1A receptor were established by measuring their ability to inhibit VIP-induced cAMP production in GH4ZD10 cells expressing serotonin 5-HT1A receptors. Both enantiomers of 5 behaved as full serotonin 5-HT1A receptor agonists in this assay, while both enantiomers of 6 behaved as weak partial agonists. The potential antipsychotic properties of (S)- and (R)-5 were evaluated by establishing their ability to inhibit d-amphetamine-induced locomotor activity in rats, while their propensity to induce extrapyramidal side-effects (EPS) in man was evaluated by determining their ability to induce catalepsy in rats. Whereas (R)-5 was capable of blocking d-amphetamine-induced locomotor activity, indicative of dopamine D2 receptor antagonism, (S)-5 even enhanced the effect of d-amphetamine, suggesting that this compound has dopamine D2 receptor-stimulating properties. Since both enantiomers also were devoid of cataleptogenic activity, they are interesting candidates for further exploring the dopamine D2/serotonin 5-HT1A hypothesis of atypical antipsychotic drug action.
authors.affiliation: Department of Medicinal Chemistry, University Centre for Pharmacy, University of Groningen, The Netherlands. ehoman@pharmacop.com
authors.forename: E J
authors.initials: EJ
authors.lastname: Homan
authors.forename: S
authors.initials: S
authors.lastname: Copinga
authors.forename: L
authors.initials: L
authors.lastname: Unelius
authors.forename: D M
authors.initials: DM
authors.lastname: Jackson
authors.forename: H V
authors.initials: HV
authors.lastname: Wikström
authors.forename: C J
authors.initials: CJ
authors.lastname: Grol
mesh_terms: D000661:Amphetamine / Q000494:pharmacology; D000818:Animals; D014150:Antipsychotic Agents / Q000138:chemical synthesis / Q000378:metabolism* / Q000494:pharmacology*; D001549:Benzamides / Q000138:chemical synthesis* / Q000378:metabolism* / Q000494:pharmacology*; D002375:Catalepsy / Q000139:chemically induced; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D015259:Dopamine Agents / Q000138:chemical synthesis / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D020128:Inhibitory Concentration 50; D007536:Isomerism; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D018340:Receptors, Adrenergic, alpha-1 / Q000378:metabolism; D018341:Receptors, Adrenergic, alpha-2 / Q000378:metabolism; D011943:Receptors, Adrenergic, beta / Q000378:metabolism; D017447:Receptors, Dopamine D1 / Q000378:metabolism; D017448:Receptors, Dopamine D2 / Q000378:metabolism; D050637:Receptors, Dopamine D3; D011985:Receptors, Serotonin / Q000378:metabolism; D044263:Receptors, Serotonin, 5-HT1; D017330:Remoxipride / Q000378:metabolism; D018490:Serotonin Agents / Q000138:chemical synthesis / Q000378:metabolism / Q000494:pharmacology; D013329:Structure-Activity Relationship; D013764:Tetrahydronaphthalenes / Q000138:chemical synthesis* / Q000378:metabolism* / Q000494:pharmacology*; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology
chemical_list: C121612:5-methoxy-2-(N-(2-(2,6-dimethoxy)benzamidoethyl)-N-n-propylamino)tetralin; C120949:5-methoxy-2-(N-(2-benzamidoethyl)-N-n-propylamino)tetralin; D014150:Antipsychotic Agents; D001549:Benzamides; C493593:DRD3 protein, human; D015259:Dopamine Agents; C493595:Drd3 protein, rat; D018340:Receptors, Adrenergic, alpha-1; D018341:Receptors, Adrenergic, alpha-2; D011943:Receptors, Adrenergic, beta; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D050637:Receptors, Dopamine D3; D011985:Receptors, Serotonin; D044263:Receptors, Serotonin, 5-HT1; D018490:Serotonin Agents; D013764:Tetrahydronaphthalenes; D017330:Remoxipride; D014660:Vasoactive Intestinal Peptide; D000661:Amphetamine; D000242:Cyclic AMP