Design and Activity Evaluation of Berberine-Loaded Dual pH and Enzyme-Sensitive Colon-Targeting Microparticles

Ulcerative colitis (UC) is a multifactorial disorder, and conventional oral berberine (BBR) suffers from poor colonic targeting. This study aimed to develop a colon-targeted microparticle system (BBR-ES MPs) based on chitosan (CS) and Eudragit S-100 to enhance BBR delivery efficiency and therapeutic efficacy in UC. Methods: BBR-CS nanocarriers were prepared via ionotropic gelation and coated with Eudragit S-100 to form pH/enzyme dual-responsive MPs. Colon-targeting performance was validated through in vitro release assays. SPF-grade male KM mice (Ethics Approval No.: JMSU-2021090301) with dextran sulfate sodium (DSS)-induced UC were divided into normal, model, BBR, and BBR-ES MPs groups. Therapeutic outcomes were evaluated by monitoring body weight, disease activity index (DAI), colon length, histopathology, inflammatory cytokines (IL-1β, IL-6, TNF-α, IL-10), and myeloperoxidase (MPO) activity via ELISA. Gut microbiota diversity was analyzed using 16S rRNA sequencing. Results: BBR-ES MP treatment significantly reduced DAI scores (p < 0.01), restored colon length, downregulated pro-inflammatory cytokines (IL-1β, IL-6, TNF-α; p < 0.05), and upregulated anti-inflammatory IL-10. Microbiota analysis revealed that the Bacteroidetes/Firmicutes ratio, which decreased in the model group, was restored post-treatment, with alpha/beta diversity approaching normal levels. BBR-ES MPs outperformed free BBR at equivalent doses. Conclusion: BBR-ES MPs achieved colon-targeted drug delivery via pH/enzyme dual-responsive mechanisms, effectively alleviating UC inflammation and modulating gut dysbiosis, offering a safe and precise therapeutic strategy for UC management.