SAR of alpha 7 nicotinic receptor agonists derived from tilorone: Exploration of a novel nicotinic pharmacophore

The well-known interferon-inducer tilorone was found to possess potent affinity for the agonist site of the alpha 7 neuronal nicotinic receptor (Ki = 56 nM). SAR investigations determined that both basic sidechains are essential for potent activity, however active monosubstituted derivatives can also be prepared if the flexible sidechains are replaced with conformationally rigidified cyclic amines. Analogs in which the fluorenone core is replaced with either dibenzothiophene-5,5-dioxide or xanthenone also retain potent activity.