Ketanserin and Spiperone as Templates for Novel Serotonin 5-HT2A Antagonists
Richard A. Glennon, Kamel Metwally, Malgorzata Dukat, Abd M. Ismaiel, Joseph De. Los Angeles, Jeffery Herndon, Milt Teitler and Nantaka Khorana
Affiliation: Department ofMedicinal Chemistry, School of Pharmacy, Virginia CommonwealthUniversity, Richmond, VA 23298 USA
The structures of ketanserin (1) and spiperone (2) were examined in detail to determine the role of various substituent groups on 5-HT2A receptor affinity and selectivity. It was found that the presence of the quinazoline ring of ketanserin detracts from selectivity and that various ring-opened analogs displayed ketanserin-like affinity and up to 30-fold enhanced selectivity. The triazaspirodecanone portion of spiperone is a major determinant of its 5-HT2A affinity and selectivity. The conformational rigidity imposed by the ring, as well as the nature of the N1-substituent, are important factors in controlling binding at 5-HT2A, 5-HT2C, 5-HT1A, and dopamine D2 receptors. Replacement of the N1-phenyl ring of spiperone with a methyl group (KML-010 48) resulted in a compound that binds at 5-HT2A receptors with slightly lower affinity than spiperone, but that lacked affinity (Ki > 10,000 nM) for 5-HT2C and 5-HT1A receptors and binds with 400-fold reduced affinity at D2 receptors.
Keywords: Ketanserin and Spiperone, Serotonin 5-HT2A, KETANSERIN ANALOGS, Quinazoline-Abbreviated Analogs, Benzoylpiperidine
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