Discovery of AD258 as a Sigma Receptor Ligand with Potent Antiallodynic Activity

Abstract

The design and synthesis of a series of 2,7-diazaspiro [4.4]nonane derivatives as potent sigma receptor (SR) ligands, associated with analgesic activity, are the focus of this work. In this study, affinities at S1R and S2R were measured, and molecular modeling studies were performed to investigate the binding pose characteristics. The most promising compounds were subjected to in vitro toxicity testing and subsequently screened for in vivo analgesic properties. Compound 9d (AD258) exhibited negligible in vitro cellular toxicity and a high binding affinity to both SRs (K i S1R = 3.5 nM, K i S2R = 2.6 nM), but not for other pain-related targets, and exerted high potency in a model of capsaicininduced allodynia, reaching the maximum antiallodynic effect at very low doses (0.6−1.25 mg/kg). Functional activity experiments showed that S1R antagonism is needed for the effects of 9d and that it did not induce motor impairment. In addition, 9d exhibited a favorable pharmacokinetic profile.

Exploring Structural Requirements for Sigma-1 Receptor Linear Ligands: Experimental and Computational Approaches

“…Liver homogenates for S1R and S2R receptor binding assays were prepared from male Sprague–Dawley rats as previously reported. − In vitro S1R ligand binding assays were carried out in Tris buffer (50 mM, pH 8), using [ 3 H]­(+)-pentazocine (2 nM) in a final volume of 0.5 mL with increasing concentrations of the test compounds. The K d value of [ 3 H]­(+)-pentazocine was 2.9 nM.…”