title: QSAR study of imidazoline antihypertensive drugs.
abstract: The hypotensive effect of imidazoline ligands was attributed to both alpha(2)-adrenergic receptors and nonadrenergic imidazoline-1 receptors (I(1)-R). Selective I(1)-R ligands, devoid of the typical side effects of other centrally acting antihypertensive drugs, could be widely used in antihypertensive therapy. Thus, there is significant interest in developing new imidazoline analogs with higher selectivity and affinity for I(1) receptors. The quantitative structure-activity relationship (QSAR) study of 12 ligands was carried out using multilinear regression method on I(1)-R and alpha(2)-adrenergic receptors binding affinities on human platelets. The compounds have been studied using Becke3LYP/3-21G (d,p) and Becke3LYP/6-31G(d,p) DFT methods. Among 42 descriptors that were considered in generating the QSAR model, three descriptors such as partial atomic charges of nitrogen in the heterocyclic moiety, distribution coefficient, and molar refractivity of the ligands resulted in a statistically significant model with R(2)=0.935 and cross-validation parameter q(2)(pre) =0.803. The validation of the QSAR models was done by cross-validation and external test set prediction. The developed multiple linear regression models for the I(1)-R ligands were aimed to link the structures to their reported I(1)-R binding affinity log(1/K(i)). The theoretical approach indicates that an increase in distribution coefficient and molar refractivity value, together with a decrease in average N-charge in the heterocyclic moiety of the ligands, causes better binding affinity for active site of the I(1) receptors. The developed QSAR model is intended to predict I(1)-R binding affinity of related compounds and to define possible physicochemical, electrical, and structural requirements for selective I(1)-receptor ligands.
authors.affiliation: Institute of Pharmaceutical Chemistry and Drug Analysis, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11000 Belgrade, Serbia. knikolic@pharmacy.bg.ac.yu
authors.forename: Katarina
authors.initials: K
authors.lastname: Nikolic
authors.forename: Slavica
authors.initials: S
authors.lastname: Filipic
authors.forename: Danica
authors.initials: D
authors.lastname: Agbaba
mesh_terms: D000959:Antihypertensive Agents / Q000737:chemistry* / Q000494:pharmacology*; D001665:Binding Sites; D054755:Imidazoline Receptors / Q000037:antagonists & inhibitors / Q000737:chemistry; D048288:Imidazolines / Q000737:chemistry* / Q000494:pharmacology*; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D021281:Quantitative Structure-Activity Relationship
chemical_list: D000959:Antihypertensive Agents; D054755:Imidazoline Receptors; D048288:Imidazolines; D008024:Ligands; C410887:imidazoline I1 receptors