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Abstract: Following previous studies focused on the search for new molecules targeting GluN2B-containing NMDA, a small series of 1-(1H-indol-3-yl)-2-(4-phenylpiperidin-1-yl)ethanone derivatives has been synthesized by using Microwave Assisted Organic Synthesis (MAOS). Given that GluN2B ligands frequently exert off-target effects we also tested their affinity towards sigma receptors. Binding assay revealed that only the 1-(5-hydroxy-1H-indol-3-yl)-2-(4-phenylpiperidin-1-yl)ethanone (7a) retained GluN2B affinity. Interestingly, the 5-methoxyindoles 5a and 6a were efficient and selective ligands toward σ2 receptor (K i values of 10nM and 20nM, respectively). Thus, in this case the discovery of new σ2 receptor selective ligands was an unexpected result emerging from the screening of cross-activity against other CNS receptors. [Copyright &y& Elsevier]

Abstract: Herein we report the synthesis, drug-likeness evaluation, and in vitro studies of new sigma (σ) ligands based on arylalkenylaminic scaffold. For the most active olefin the corresponding arylalkylamine was studied. Novel arylalkenylamines generally possess high σ1 receptor affinity (K i values <25nM) and good σ1/σ2 selectivity (K iσ2 >100). Particularly, the piperidine derivative (E)-17 and its arylalkylamine analog (R,S)-33 were observed to be excellent σ1 receptor ligands (K i =0.70 and 0.86nM, respectively) and to display significantly high selectivity over σ2, μ-, and κ-opioid receptors and phencyclidine (PCP) binding site of the N-methyl-d-aspartate (NMDA) receptors. Moreover in PC12 cells (R,S)-33 promoted the nerve growth factor (NGF)-induced neurite outgrowth and elongation. Co-administration of the selective σ1 receptor antagonist BD-1063 totally counteracted this effect, confirming that σ1 receptors are involved in the (R,S)-33 modulation of the NGF effect in PC12 cells and suggesting a σ1 agonist profile. As a part of our work, a threedimensional σ1 pharmacophore model was also developed employing GALAHAD methodology. Only active compounds were used for deriving this model. The model included two hydrophobes and a positive nitrogen as relevant features and it was able to discriminate between molecules with and without affinity toward σ1 receptor subtype. [Copyright &y& Elsevier]