1-aryl-4-[(5-methoxy-1,2,3, 4-tetrahydronaphthalen-1-yl)alkyl]piperazines and their analogues: influence of the stereochemistry of the tetrahydronaphthalen-1-yl nucleus on 5-HT1A receptor affinity and selectivity versus alpha1 and D2 receptors. 5.
Some 1-aryl-4-[(5-methoxy-1,2,3, 4-tetrahydronaphthalen-1-yl)-n-propyl]piperazines and their alkylamino and alkylamido analogues, previously studied as 5-HT1A ligands, were prepared in enantiomerically pure form, and their absolute configuration was determined by chemical correlation or by chiroptical properties. They were evaluated for in vitro 5-HT1A, D2, and alpha1 receptor affinity by radioligand binding assays, to study the influence of the chiral carbon atom of the tetrahydronaphthalene nucleus on the 5-HT1A affinity and selectivity. Results indicated that, as regarding the 5-HT1A receptor affinity, there was no difference in affinity between (-)- and (+)-enantiomers as well as the racemate of each compound. The stereochemistry, instead, influenced the selectivity: all (-)-enantiomers displayed affinity values higher than those of (+)-isomers at D2 receptors, and conversely, all (+)-enantiomers displayed affinity values higher than those of (-)-isomers at alpha1 receptors. As a result of this trend, it is not possible to predict the isomer with a better selectivity profile. However, compounds (S)-(+)-2, (S)-(+)-4, and (R)-(+)-6 displayed high affinity for the 5-HT1A receptor (IC50 values ranging between 7.0 and 2.3 nM) and good selectivity (>/=250-fold) versus both D2 and alpha1 receptors. Furthermore, compounds (S)-(+)-4 and (R)-(-)-4 were submitted to the [35S]GTPgammaS binding assay for a preliminary evaluation of their intrinsic activity on the 5-HT1A receptor.
Perrone
R
R
Dipartimento Farmaco-Chimico, Università di Bari, via Orabona, 4, 70126 Bari, Italy.
Berardi
F
F
Colabufo
N A
NA
Leopoldo
M
M
Tortorella
V
V
D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D010879:Piperazines / Q000737:chemistry* / Q000378:metabolism; D011869:Radioligand Assay; D018340:Receptors, Adrenergic, alpha-1 / Q000378:metabolism*; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D011985:Receptors, Serotonin / Q000378:metabolism*; D044263:Receptors, Serotonin, 5-HT1; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D013764:Tetrahydronaphthalenes / Q000737:chemistry*