Sigma receptor is a transmembrane non‐GPCR protein expressed mainly in the endoplasmic reticulum membrane associated with mitochondria. It is classified into two types: Sigma‐1 (S1R) and Sigma‐2 (S2R) based on their biological functions. S1R has been implicated in many neurological disorders such as anxiety, schizophrenia, and depression. Therefore, S1R ligands possess a variety of potential clinical applications with a great interest in the treatment of neuropathic pain. In this study, we report the discovery of a novel lead compound for S1R binding, based on the thiazolidine‐2,4‐dione nucleus. We have explored hydrophobic groups of different sizes on both sides of the five‐membered ring scaffold guided by the crystal structure of S1R. Six compounds showed more than 50% displacement of the radioligand at 10 µM concentration with compound 6c resulting in 100% displacement and a Ki of 95.5 nM. Moreover, compounds 6c and 6e showed a significant selectivity over S2R. In addition, molecular docking predicted that all the compounds showed the critical salt bridge with Glu172 with variable degrees of π‐stacking interaction with Tyr103. Upon optimization, this series of compounds could represent potential clinically useful S1R ligands for pain management.

Background: Colon delivery systems are designed for the oral delivery of active compounds in the large intestine. Food-grade copolymers Eudraguard® Biotic (EUGB) and control (EUGC) have been investigated to develop colloidal systems loading natural active ingredients. Methods: In this study, we evaluated the degradation process of these matrices in simulated gastric, intestinal and colonic conditions. Microparticles made of EUGB and EUGC, alone or in combination, were loaded with the model compound resveratrol (RSV). A parallel study was performed on in vitro RSV release and SEM analysis of microparticles kept at different pH values. Results: All systems ensured a limited gastric release of RSV (below 20%), presenting only small pores on the surface of microparticles treated with simulated gastric fluid. EUGB microparticles showed the maximum release in simulated colon fluid (SCF), showing a complete dissolution of the microparticle matrix. The EUGC-based system allowed a prolonged release of RSV over time, and in SCF, it showed only partial degradation. Using mixed EUGB/EUGC matrices, a prolonged RSV release was observed along the intestinal tract. Conclusion: Overall, EUGB and EUGC copolymers were able to modulate and localize the release of entrapped cargo in the small intestine and colon. They could have interesting applications in treating bowel diseases synergistically with other therapeutic strategies.

Herein, we describe our efforts to identify sigma receptor 1 (S1R) ligands through a screening campaign on our in-house collection of piperidine/piperazine-based compounds. Our investigations led to the discovery of...

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.