Synthesis, anticonvulsant activity and molecular modeling study of some new hydrazinecarbothioamide, benzenesulfonohydrazide, and phenacylacetohydrazide analogues of 4(3H)-quinazolinone q Huda S. A. Al-Salem a , Gehan H. Hegazy b , Kamal E. H. El-Taher c , Shahenda M. El-Messery d , Abdulrahman M. Al-Obaid a , Hussein I. El-Subbagh e,f,⇑ a Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, PO Box 2457, Riyadh 11451, Saudi Arabia b Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Cairo University, Cairo 11562, Egypt c Department of Pharmacology, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia d Department of Pharmaceutical Organic Chemistry, Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt e Department of Medicinal Chemistry, Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt f Department of Pharmaceutical Chemistry, Faculty of Pharmaceutical Sciences & Pharmaceutical Industries, Future University, 12311 Cairo, Egypt article info Article history: Received 29 November 2014 Revised 6 February 2015 Accepted 11 February 2015 Available online 20 February 2015 Keywords: Synthesis 4(3H)-Quinazolinones Anticonvulsant activity Molecular modeling study abstract A new series of quinazoline analogues was designed and synthesized to get the target compounds 18–21, 30–41, 46–53, and 57–76. The Obtained compounds were evaluated for their anticonvulsant activity using PTZ and picrotoxin convulsive models. Compounds 47, 63, 68 and 73 proved to be the most active compounds in this study with a remarkable 100% protection against PTZ induced convulsions. Compounds 47, 63, 68 and 73 proved to be 10, 4, 4, and 5 fold more active, respectively than the used positive control sodium valproate. Structure activity correlation concluded valuable pharmacophoric information which confirmed by molecular modeling studies. Molecular docking study of 68 suggested its agonistic behavior toward GABA A receptor. The studied quinazoline analogues could be considered as useful templates for future development and further derivatization. Ó 2015 Elsevier Ltd. All rights reserved. Despite the broad and growing array of antiepileptic drugs (AEDs) available for treatment, approximately 30% of epileptic patients have inadequate seizure control and a further 25% suffer from significant adverse effects. 1 Thus there is an ongoing need to develop more AEDs that are effective and endowed with improved safety profile. Recently, a number of fused pyrimidine derivatives became known as potential drug molecules against various types of diseases. One of the most important compound families are quinazolinones which are the building blocks for approximately 150 naturally occurring alkaloids and drugs. 2 Literature survey reveals that natural quinazolinones and their synthetic analogues possess a variety of pharmacological activities, including antitumor, 3–5 CNS depressant, 6 antimicrobial, 7,8 and muscle relaxant activities. 9,11 Methaqualone (1) is an important landmark in the field of syn- thetic anticonvulant, 12 and its 6-chloro analogue 2 which proved to possess marked anticonvulsant action, 1.5 times more potent than phenytoin sodium (3) against electroshock induced convulsions and 10 times more potent than troxidone (4) against pentylenete- trazol induced seizures. 13,14 Several quinazolinones related to 1 have been synthesized and tested; a persistent problem arises from the fact that nearly every derivative exhibited neurotoxicity values (TD 50 ) that are less than or only slightly higher than the ED 50 values. Consequently, the protective index (PI) corresponding to TD 50 /ED 50 is too low. 15,16 Modification of the 2-methyl group of 1 by some other chemical moiety yielded structural analogues with potent anticonvulsant activity. 17 In continuation to our previous efforts, recently some new quinazoline analogues that possess remarkable anticonvulsant activity were prepared in our laborato- ry such as 5, (ED 50 73.1 mg/kg), which showed a 100% protection against PTZ induced clonic convulsion (Chart 1). 18–20 Based on the previous mentioned considerations, bearing in mind the inherited anticonvulsant potency of quinazoline nuclei, the CNS activity enhancement of the thioacetic acid hydrazide, and the potentiating effect of alkoxy functions and halogens to the anticonvulsant activity, 2,10 the combination of all these fea- tures in one structure to produce derivatives 6–9 was rationalized, (Chart 2). A new series of quinazoline analogues were synthesized http://dx.doi.org/10.1016/j.bmcl.2015.02.025 0960-894X/Ó 2015 Elsevier Ltd. All rights reserved. q Part of the European Patent, EP 2 740 727 A1, June 2014; See Ref. 21. ⇑ Corresponding author. Tel.: +20 50 2247800; fax: +20 50 2247900. E-mail address: subbagh@yahoo.com (H.I. El-Subbagh). Bioorganic & Medicinal Chemistry Letters 25 (2015) 1490–1499 Contents lists available at ScienceDirect Bioorganic & Medicinal Chemistry Letters journal homepage: www.elsevier.com/locate/bmcl