High affinity central benzodiazepine receptor ligands: synthesis and structure–activity relationship studies of a new series of pyrazolo[4,3-c]quinolin-3-ones Original Research Article

A large series of 2-aryl(heteroaryl)-2,5-dihydropyrazolo[4,3-c]quinolin-3-(3H)-ones, carrying appropriate substituents at the quinoline and N2-phenyl rings, were prepared and tested as central benzodiazepine receptor ligands. Results from structure–affinity relationship studies were in full agreement with previously proposed pharmacophore models and, in addition, quantitative structure–activity analysis gave further significant insight into the main molecular determinants of high benzodiazepine receptor affinity. The intrinsic activity of some active ligands was also determined and preliminary discussed.