| 17194034 |
Sharma BK, Singh P, Sharma S: Quantitative structure-activity relationship study of new potent and selective antagonists at the 5-HT (1A) and adrenergic alpha (1d) receptors: Derivatives of spiroethyl phenyl (substituted) piperazine. J Enzyme Inhib Med Chem. 2006 Oct;21(5):601-7.
The antagonistic activities of derivatives of spiroethyl phenyl (substituted) piperazine at the 5-HT (1A) and adrenergic alpha (1d) receptors is quantitatively analyzed employing physicochemical and structural parameters. The derived correlation equation revealed that a substituent, other than 2-CH3 in the phenyl ring, having higher molar refraction, MR, and a substituent producing higher positive field effect at the 3-position are beneficial in increasing the binding affinity at the 5-HT (1A) receptor. In addition, a less hydrophobic substituent at the 4-position is also helpful in augmenting the binding affinity. The 5-R substituents which have higher MR values, however, elicit a detrimental effect. Two disubstituted compounds which are not present in the original data-set and have higher theoretical binding affinities are designed from the correlation equation. These compounds consisting of 2-OCH (CH3) 2, 3-Cl and 2-C3H7, 3-Cl in the phenyl ring, have theoretical pK (i) values 10.57 and 10.12 respectively. For the adrenergic alpha (1d) receptor, a less bulky group at the 3-position with 5-Cl (or simply a 3-Cl) is advantageous in increasing the binding affinity. Likewise, a substituent exhibiting a less negative resonance effect at the 4-position and the substituent with low polarizability and showing more a negative resonance effect at the 5-position are suitable for enhancement of the binding affinity. The analysis provides the grounds for rationalizing substituent selection in designing better potency antagonists in the series. |
163(2,2,2,3) |