Design, synthesis and neuropharmacological evaluation of new 2,4-disubstituted-1,5-benzodiazepines as CNS active agents.

Benzodiazepines (BZDs) represent a class of privilege scaffold in the modern era of medicinal chemistry as CNS active agents and BZD based drugs are used to treat different psychotic disorders. Inspired from the therapeutic potential of BZDs as promising CNS active agents, in the present work three different series of 1,5-benzodiazepines bearing various substitutions at position 2 and 4 of the benzodiazepine core were synthesized by condensing different substituted chalcones with o-phenylenediamine in the presence of piperidine as a base catalyst. Structural characterization of title compounds was done by using various analytical techniques such as IR, NMR, elemental analysis and mass spectral data. All the synthesized compounds (9a-d, 10a-e and 11a-c) were subjected to in vivo neuropharmacological studies to evaluate their CNS depressant and antiepileptic activity. Results of in vivo evaluation data showed that analogue 11b exhibited potent CNS depressant activity which was comparable to the standard drug diazepam. Compounds 10b and 10c displayed significant antiepileptic activity however they were less potent than the standard drug phenobarbitone. Molecular docking studies were performed using MOE software to find the interaction pattern and binding mode at the GABAA receptor (PDB Id: 6HUP). The results of the docking studies were in good agreement with the observed in vivo activity and revealed the satisfactory binding mode of the compounds within the binding site of the protein. The docking scores for the most promising candidates 10c, 11b and Diazepam were found to be -9.18, -9.46 and -9.88, respectively. Further, the compounds showed compliance with the Lipinski's 'rule of five' and exhibited favourable drug-likeness scores. The identified leads can be explored further for the design and development of new BZD based psychotropic agents.

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Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.