title: Novel agonists of benzodiazepine receptors: design, synthesis, binding assay and pharmacological evaluation of 1,2,4-triazolo[1,5-a]pyrimidinone and 3-amino-1,2,4-triazole derivatives.
abstract: Agonists of benzodiazepine (BZD) binding site in GABA receptors are widely used in clinical practice. In spite of their benefits they have several side effects, so synthesis of new agonists of these receptors to get more specific effect and better profile of adverse drug reactions is still continued. Novel BZD agonists were designed based on the pharmacophore/receptor model of BZD binding site of GABAA receptor. Energy minima conformers of the designed compounds and estazolam, a known BZD receptor agonist, were well superimposed in conformational analysis. Docking studies revealed that the carbonyl group of the compound 4c, 3-(2-chlorobenzyl)-5-methyl-2-phenyl-[1,2,4]triazolo[1,5-a]pyrimidin-7(3H)-one, was near the nitrogen moiety of triazole ring of estazolam providing the hydrogen bond acceptor in proper direction in the BDZ-binding site of GABAA receptor model (α1β2ϒ2). The designed compounds were synthesized and their in vitro affinity for the central BZD receptor was determined. Most of the novel compounds had better affinity for the BZD site of action on GABAA receptor complex than diazepam. Finally, the novel compound 4c with the best affinity in radioligand receptor binding assay (Ki=0.42 nM and IC50=0.68 nM) was selected as candidate for in vivo evaluation. This compound showed significant hypnotic activity and weak anticonvulsant effect with no impairment on learning and memory performance in mouse. The pharmacological effects of the compound 4c were antagonized by flumazenil, a BZD antagonist, which confirms the involvement of BZD receptors in the biological effects of the novel ligand.
authors.affiliation: Department of Pharmacology and Toxicology, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Faizi
authors.affiliation: Department of Pharmaceutical Chemistry, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Sara
authors.initials: S
authors.lastname: Dabirian
authors.affiliation: Department of Pharmacology and Toxicology, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Hamed
authors.initials: H
authors.lastname: Tajali
authors.affiliation: Department of Pharmaceutical Chemistry, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Ahmadi
authors.affiliation: Department of Pharmaceutical Chemistry, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Elham Rezaee
authors.initials: ER
authors.lastname: Zavareh
authors.affiliation: Department of Pharmaceutical Chemistry, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Soraya
authors.initials: S
authors.lastname: Shahhosseini
authors.affiliation: Department of Pharmaceutical Chemistry, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Electronic address: sa_tabatabai@sbmu.ac.ir.
authors.forename: Sayyed Abbas
authors.initials: SA
authors.lastname: Tabatabai
mesh_terms: D000818:Animals; D000927:Anticonvulsants / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D015195:Drug Design; D058785:GABA-A Receptor Agonists / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008958:Models, Molecular; D011744:Pyrimidinones / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D011963:Receptors, GABA-A / Q000737:chemistry; D014230:Triazoles / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D000927:Anticonvulsants; D058785:GABA-A Receptor Agonists; D011744:Pyrimidinones; D011963:Receptors, GABA-A; D014230:Triazoles
keywords: Benzodiazepine agonists; Binding assay; Hypnotic activity; Synthesis