Therapies for the treatment of pain and inflammation continue to pose a global challenge, emphasizing the significant impact of pain on patients’ quality of life. Therefore, this study aimed to investigate the effects of 4-(Phenylselanyl)-2H-chromen-2-one (4-PSCO) on pain-associated proteins through computational molecular docking tests. A new pharmaceutical formulation based on polymeric nanocapsules was developed and characterized. The potential toxicity of 4-PSCO was assessed using Caenorhabditis elegans and Swiss mice, and its pharmacological actions through acute nociception and inflammation tests were also assessed. Our results demonstrated that 4-PSCO, in its free form, exhibited high affinity for the selected receptors, including p38 MAP kinase, peptidyl arginine deiminase type 4, phosphoinositide 3-kinase, Janus kinase 2, toll-like receptor 4, and nuclear factor-kappa β. Both free and nanoencapsulated 4-PSCO showed no toxicity in nematodes and mice. Parameters related to oxidative stress and plasma markers showed no significant change. Both treatments demonstrated antinociceptive and anti-edematogenic effects in the glutamate and hot plate tests. The nanoencapsulated form exhibited a more prolonged effect, reducing mechanical hypersensitivity in an inflammatory pain model. These findings underscore the promising potential of 4-PSCO as an alternative for the development of more effective and safer drugs for the treatment of pain and inflammation.

Background/Objectives: Recognizing the current limitations in rheumatoid arthritis (RA) treatments, especially in managing pain and inflammation, there is an urgent need to develop and explore new therapeutic strategies. In this study, we devised two innovative approaches using nanotechnology for treating RA. We evaluated the effectiveness of compound 4-(phenylselanyl)-2H-chromen-2-one (4-PSCO) in three forms: free, as well as in nanoemulsified (4-PSCO NE) and nanoencapsulated (4-PSCO NC) formulations. Methods: Arthritis was induced in mice by intraplantar injection of Freund’s complete adjuvant (CFA; 0.1 mL). The 4-PSCO free, 4-PSCO NE, and 4-PSCO NC (1 mg/kg, orally) treatments were administered daily for 15 days. We assessed disease signs, symptoms, mechanical and thermal sensitivities, neurobehavioral deficits, and activities of myeloperoxidase (MPO), Na⁺, K⁺-ATPase, and acetylcholinesterase (AChE), as well as oxidative stress markers. Results: Our study demonstrates, for the first time, that both 4-PSCO NC and 4-PSCO NE inhibit the clinical signs of RA in mice, including inflammation. Moreover, both formulations alleviated pain and anxiety behaviors while restoring AChE activity and decreasing oxidative stress in the cerebral cortex. Notably, only the 4-PSCO NC treatment increased the time animals spent in the open arms of the elevated plus-maze. It lowered TBARS levels in the cerebral cortex, spinal cord, and paws, showcasing its advantages over the free 4-PSCO and 4-PSCO NE. Conclusions: These findings highlight the therapeutic potential of 4-PSCO, especially the polymeric nanocapsule, as a practical option for treating both the symptoms and underlying mechanisms of RA.