Synthesis and Biological Characterization of 3-Substituted-1H-indoles as Ligands of GluN2B-Containing N-Methyl-d-aspartate Receptors

As an extension of our studies, novel indole derivatives were rationally designed and synthesized as ligands targeted to GluN2B/NMDA receptors. The 2-(4-benzylpiperidin-1-yl)-1-(6-hydroxy-1H-indol-3-yl)ethanone (4i) and 1-(4-benzylpiperidin-l-yl)-2-(6-hydroxy-1H-indol-3-yl)ethane-1,2-dione (6i) showed high binding affinity in [H-3]ifenprodil displacement assay. By computational studies, we suggested the hypothetical interactions playing a significant role during the binding process. However, in functional and in vivo studies the most potent compound 4i did not show any activity whereas it displayed relevant affinity toward the sigma(2) receptor.