Achillea wilhelmsii-Incorporated Chitosan@Eudragit Nanoparticles Intended for Enhanced Ulcerative Colitis Treatment.

Achillea wilhelmsii (A. wilhelmsii) contains several therapeutic phytochemicals, proposing a protective effect on inflammatory responses in autoimmune diseases such as ulcerative colitis (UC). However, its activities against UC encounter multiple obstacles. The current study aimed to formulate a colon-specific delivery of A. wilhelmsii for treating UC using chitosan nanoparticles (NPs) and Eudragit S100 as a mucoadhesive and pH-sensitive polymer, respectively. Core chitosan NP was loaded with A. wilhelmsii extract, followed by coating with Eudragit S100. Then, physicochemical characterizations of prepared NPs were conducted, and the anti-UC activity in the rat model was evaluated. The relevant physicochemical characterizations indicated the spherical NPs with an average particle size of 305 ± 34 nm and high encapsulation efficiency (88.6 ± 7.3%). The FTIR (Fourier transform infrared) analysis revealed the Eudragit coating and the extract loading, as well as the high radical scavenging ability of A. wilhelmsii was confirmed. The loaded NPs prevented the extract release in an acidic pH-mimicking medium and presented a complete release thereafter at a colonic pH. The loaded NPs markedly mitigated the induced UC lesions in rats, reflected by reducing inflammation, ulcer severity, and UC-related symptoms. Further, histopathological analysis exhibited reducing the extent of the inflammation and damage to colon tissue, and the determination of the involved pro-inflammatory cytokines in serum showed a significant reduction relative to free extract. The present results show that chitosan NPs containing A. wilhelmsii extract coated with Eudragit having proper physicochemical properties and substantial anti-inflammatory activity can significantly improve colonic lesions caused by UC.