Computer-aided molecular modeling, synthesis, and biological evaluation of 8-(benzyloxy)-2-phenylpyrazolo[4,3-c]quinoline as a novel benzodiazepine receptor agonist ligand

Using computer-aided conformational analysis, based on molecular dynamics simulation, cluster analysis, and Monte Carlo techniques, we have designed and synthesized compounds in which a benzyloxy substituent has been incorporated into a series of pyrazoloquinoline benzodiazepine receptor (BZR) ligands. Earlier studies had shown that the benzyloxy group could act as part of the agonist pharmacophoric determinant in the β-carboline ring system. Furthermore, the agonist β-carboline had been correlated with a binding site orientation and volume fit for an agonist 6-phenylimidazobenzodiazepine carboxylate. The present study was undertaken to determine whether the benzyloxy substituent could be used as an agonist pharmacophoric descriptor for the phenylpyrazolo[4,3-c]quinolin-3-one BZR ligands. The results of a determination of GABA shift ratios for the synthetic ligands indicate that 8-(benzyloxy)-2-phenylpyrazolo[4,3-c]quinolin-3-one can be predicted to be an agonist at the BZR.