Structure-affinity relationship study on N-(1,2,3,4-tetrahydronaphthalen-1-yl)-4-aryl-1-piperazinealkylamides, a new class of 5-hydroxytryptamine(7) receptor agents

• Published in: Journal of medicinal chemistry Vol. 47; no. 26; pp. 6616 - 6624
• Main Authors: Leopoldo, M, Berardi, F, Colabufo, NA, Contino, M, Lacivita, E, Niso, M, Perrone, R, Tortorella
• Format: Journal Article
• Language: English
• Published: WASHINGTON Amer Chemical Soc 16.12.2004
• Subjects: Chemistry, Medicinal; Life Sciences & Biomedicine; Pharmacology & Pharmacy; Science & Technology; SEROTONIN RECEPTOR; SELECTIVE ANTAGONISTS; 5-HT7 RECEPTOR; IN-SITU HYBRIDIZATION; ANTIPSYCHOTIC AGENTS; MOLECULAR-CLONING; RAT-BRAIN; ADENYLATE-CYCLASE; DERIVATIVES; EXPRESSION
• ISSN: 0022-2623; 1520-4804
• DOI: 10.1021/jm049702f

A series of N-(1,2,3,4-tetrahydronaphthalen-1-yl)-4-aryl-1-piperazinealkylamides was prepared and their affinity for serotonin (5-hydroxytryptamine, 5-HT) 5-HT7, 5-HT1A, and 5-HT2A receptors was measured by in vitro binding assays. In relation to 5-HT7 receptor affinity, receptor binding studies indicated that (i) the optimal alkyl chain length was five methylenes, (ii) an unsubstituted 1,2,3,4-tetrahydronaphthalenyl nucleus was preferred, and (iii) the substitution pattern of the aryl ring linked to the piperazine ring played a crucial role. Several compound with high affinity for 5-HT7 receptors were identified. Among them, 4-(2-methoxyphenyl)-N-(1,2,3,4-tetrahydronaphthalen-1-yl)-1-piperazinehexanamide (28), 4-(2-acetylphenyl)-N-(1,2,3,4-tetrahydronaphthalen-1-yl)-1-piperazinehexanamide (34), 4-(2-methylthlophenyl)-N-(1,2,3,4-tetrahydronaphthalen-1-yl)-1-piperazinehexanamide (44), 4-(2-hydroxyphenyl)-N-(1,2,3,4-tetrahydronaphthalen-1-yl)-1-piperazinehexanamide (46), and 4-(2-methylphenyl)-N-(1,2,3,4-tetrahydronaphthalen-1-yl)-1-piperazinehexanamide (49) were assayed for the 5-HT7 receptor-mediated relaxation of substance P-induced guinea pig ileum contraction. Compounds 28, 44, and 49 behaved as full agonists and compound 34 as a partial agonist, whereas derivative 46 acted as an antagonist. Among the compounds presented here, it emerged that 44 was identified as a potent 5-HT7 receptor agonist (K-i = 0.22 nM, EC50 = 2.56 muM), endowed with selectivity over 5-HT1A and 5-HT2A receptors (200-fold and > 1000-fold, respectively).