Hesperidin-loaded Eudragit S100 nanoparticles alleviate ulcerative colitis by repairing intestinal barrier and modulating gut microbiota.

Ulcerative colitis (UC) is a chronic inflammatory bowel disease with no curative therapy. Hesperidin (HDN) exhibits potent anti-inflammatory and antioxidant properties, but its poor solubility limits its therapeutic application. Here, we developed a colon-targeted nano-formulation by encapsulating HDN in pH-responsive Eudragit S100 nanoparticles (HDN-EUD NPs). The nanoparticles were optimized using Box-Behnken Design, yielding uniform spherical morphology with a mean particle size of 174.4 nm and encapsulation efficiency of 83.98%. HDN-EUD NPs remained stable in simulated gastric and intestinal fluids but rapidly disintegrated in simulated colonic fluid, releasing 74% of HDN within 2 h. At the cellular level, HDN-EUD NPs exhibited excellent biocompatibility and significantly enhanced protection against H₂O₂-induced oxidative stress and apoptosis. In vivo biodistribution confirmed prolonged colonic retention of HDN-EUD NPs. In a DSS-induced UC mouse model, HDN-EUD NPs treatment significantly alleviated disease symptoms, as evidenced by attenuated body weight loss, reduced disease activity index (2.06 vs. 3.61), and restored colon length (6.8 cm vs. 4.5 cm) compared to the DSS group. Mechanistically, HDN-EUD NPs repaired the intestinal barrier by upregulating tight junction proteins ZO-1 and Occludin, downregulated pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) and myeloperoxidase activity (from 3.56 to 1.02 U/g) in colon tissue, and restored gut microbiota balance by increasing beneficial bacteria (Prevotellaceae, Bifidobacteriaceae) while decreasing harmful taxa (Sutterellaceae, Bacteroidaceae). Biosafety assessments revealed no obvious toxicity. Overall, this colon-targeted nano-formulation effectively delivered HDN to the colon and enhanced its therapeutic efficacy, representing a promising preclinical candidate for UC therapy.