Computer-assisted design, synthesis, binding and cytotoxicity assessments of new 1-(4-(aryl(methyl)amino)butyl)-heterocyclic sigma 1 ligands

Abstract

In this work we applied a blend of computational and synthetic techniques with the aim to design, synthesize, and characterize new σ1 receptor (σ1R) ligands. Starting from the structure of previously reported, high-affinity benzoxazolone-based σ1 ligands, the three-dimensional homology model of the σ1R was exploited for retrieving the molecular determinants to fulfill the optimal pharmacophore requirements. Accordingly, the benzoxazolone moiety was replaced by other heterocyclic scaffolds, the relevant conformational space in the σ1R binding cavity was explored, and the effect on σ1R binding affinity was ultimately assessed. Next, the compounds designed in silico were synthesized, and their affinity and selectivity toward σ1 and σ2 receptors were tested. Finally, a representative series of best σ1R binders were assayed for cytotoxic activity on the SH-SY5Y human neuroblastoma cell line. Specifically, the new 4-phenyloxazolidin-2-one derivatives 2b (i.e., (R)-2b and (S)-2b) emerged as potential leads for further development as σ1R agents, as they were found endowed with the highest σ1R affinity (Kiσ1 values in the range 0.95-9.3 nM), and showed minimal cytotoxic levels exhibited in the selected, cell-based test, in line with a σ1R agonist behavior.

Sigmar1’s Molecular, Cellular, and Biological Functions in Regulating Cellular Pathophysiology

“…Moderate Sigmar1 (Ki 860 nM) (Villard et al, 2011) Agonist (Vamvakidès, 2002;Villard et al, 2011;Christ et al, 2019) − Muscarinic acetylcholine receptor-inhibitor (Villard et al, 2011;Christ et al, 2019) − (+)-SKF-10047 Sigmar1 (Ki 54-597 nM) > Sigmar2 (Ki 11.17-39.74 µM) (Hellewell et al, 1994;Vilner and Bowen, 2000) Agonist (Hellewell et al, 1994;Vilner and Bowen, 2000) − NMDA receptor antagonist, enhances acetylcholine release (Hiramatsu and Hoshino, 2005) Inhibits Na v channels in Sigmar1 knockout cells (Johannessen et al, 2009(Johannessen et al, , 2011 Fluvoxamine Sigmar1 (Ki 36 nM) > Sigmar2 (Ki 8,439 nM) (Narita et al, 1996) Agonist (Narita et al, 1996;Tagashira et al, 2010;Bhuiyan et al, 2011b) − Serotonin reuptake inhibitor (Fu et al, 2012;Narita et al, 1996) − DTG Sigmar1 (Ki 38-203 nM) =Sigmar2 (Ki13-58 nM) (Koe et al, 1989;Hellewell et al, 1994;Vilner and Bowen, 2000) Agonist (Walker et al, 1992;Marrazzo et al, 2011;Zampieri et al, 2016) Agonist (Walker et al, 1992;Marrazzo et al, 2011;Zampieri et al, 2016) − Inhibits Na v channels in Sigmar1 knockout cells (Johannessen et al, 2009(Johannessen et al, , 2011 DHEA Moderate Sigmar1 (Ki 2.96 µM)…”

Small Molecules Selectively Targeting Sigma-1 Receptor for the Treatment of Neurological Diseases

“…In 2016, Zampieri et al . designed 1-(4-(aryl­(methyl)­amino)­butyl)-heterocyclic derivatives as substitutes for benzoxazolones ( e.g.…”

“…99 and 100 hold excellent σ 1 receptor selectivity profiles over σ 2 receptors (ratio: up to 389) and 40 other receptors including H 1 , 5-HT 3 , and μ opioid receptors. 192 In 2016, Zampieri et al 193 designed 1-(4-(aryl(methyl)amino)butyl)-heterocyclic derivatives as substitutes for benzoxazolones (e.g., 98) based upon modeling. As shown in Figure 18, the 4-phenyloxazolidin-2-one derivatives (R)-101 and (R)-102 achieved low nanomolar σ 1 receptor affinity (K i = 2.9 nM and 7.7 nM, respectively) and selectivity over σ 2 receptors (K i > 3000 nM and 603 nM, respectively), and minimal cytotoxicity in the MTT viability assay employing human SH-SY5Y neuroblastoma cells (<15% inhibition @ 50 μM).…”

Direct and Catalytic Amide Synthesis from Ketones via Transoximation and Beckmann Rearrangement under Mild Conditions

“…H 2 18 O used was 99% 18 O-labeled water made by Taiyo Nippon Sanso Corporation. Most of the amides were characterized by 1 H NMR for comparison to previous reports. ,,,,,,− …”