4-quinolone derivatives: High-affinity ligands at the benzodiazepine site of brain GABA(A) receptors. synthesis, pharmacology, and pharmacophore modeling

The 3-ethoxycarbonyl-4-quinolone compound I has previously been identified via a database search as an interesting lead compound for ligand binding at the benzodiazepine site of GABA(A) receptors (Kahnberg et al. J. Mol. Graphics Modelling 2004, 23, 253-261). Pharmacophore-guided optimization of this lead compound yielded a number of high-affinity ligands for the benzodiazepine site including compounds 20 and 23-25 displaying sub-nanomolar affinities. A few of the compounds have been tested on the alpha(1)beta(2)gamma(2s) and alpha(3)beta(2)gamma(2s) GABA(A) receptor subtypes, and two of the compounds (5 and 19) display selectivity for alpha(1) versus alpha(3)-containing receptors by a factor of 22 and 27, respectively. This selectivity for alpha(1)beta(2)gamma(2s) is in the same range as that for the well-known alpha(1) subunit selective compound zolpidem.