Benzodiazepine-induced hyperphagia: development and assessment of a 3D pharmacophore by computational methods.

Benzodiazepine receptor (BDZR) ligands are structurally diverse compounds that bind to specific binding sites on GABA(A) receptors and allosterically modulate the effect of GABA on chloride ion flux. The binding of BDZR ligands to this receptor system results in activity at multiple behavioral endpoints, including anxiolytic, sedative, anticonvulsant, and hyperphagic effects. In the work presented here, a computational procedure developed in our laboratory has been used to obtain a 3D pharmacophore for ligand recognition of the GABA(A)/BDZRs initiating the hyperphagic response. To accomplish this goal, 17 structurally diverse compounds, previously assessed in our laboratory for activity at the hyperphagic endpoint, were used. The result is a four-component 3D pharmacophore. It consists of two proton acceptor atoms, the centroid of an aromatic ring and the centroid of a hydrophobic moiety in a common geometric arrangement in all compounds with activity at this endpoint. This 3D pharmacophore was then assessed and successfully validated using three different tests. First, two BDZR ligands, which were included as negative controls in the set of seventeen compounds used for the pharmacophore development, did not fit the pharmacophore. Second, some benzodiazepine ligands known to have activity at the hyperphagia endpoint, but not included in the pharmacophore development, were used as positive controls and were found to fit the pharmacophore. Finally, using the 3D pharmacophore developed in the present work to search 3D databases, over 50 classical benzodiazepines were found. Among them, were benzodiazepine ligands known to have an effect at the hyperphagic endpoint. In addition, the novel compounds also found in this search are promising therapeutic agents that could beneficially affect feeding behavior.