Comparative pharmacodynamic material basis of oral and colonic administration of Baitouweng decoction in experimental ulcerative colitis.

ETHNOPHARMACOLOGICAL RELEVANCE: Baitouweng Decoction (BTWD) is a traditional Chinese medicine formula widely used in clinical practice for treating ulcerative colitis (UC). However, its precise therapeutic mechanisms remain unclear.

AIM OF THE STUDY: This study investigates the therapeutic effects of BTWD administered via colon and oral routes in a UC model induced by fecal microbiota transplantation (FMT) and dextran sodium sulfate (DSS). It further explores the distinct pharmacological mechanisms associated with each route of administration.

MATERIALS AND METHODS: Male rats with UC induced by human-derived FMT and DSS were treated with BTWD via oral or colonic administration. Therapeutic outcomes were evaluated through clinical indicators and histopathology. Drug metabolites in serum and colon contents were analyzed by Ultra Performance Liquid Chromatography-Q Exactive-Orbitrap Mass Spectrometer (UPLC-QE-Orbitrap MS). Serum and fecal metabolomics identified disease-related biomarkers. Potential active substances were screened by correlating serum and fecal biomarkers with BTWD-derived components. Key active substances and targets were identified through network pharmacology and molecular docking, clarifying the pharmacological basis of each administration route. Surface plasmon resonance (SPR) and Western blot were performed to experimentally validate the binding interactions and target protein expression.

RESULTS: Both administration routes of BTWD significantly alleviated UC symptoms. Compared to the model group, BTWD-treated rats exhibited reduced weight loss, lower disease activity index (DAI) scores, and recovered colon length. Serum levels of pro-inflammatory cytokines IL-6, IL-17, and IL-1β were decreased, while anti-inflammatory IL-10 was increased. Expression of Occludin and MUC2 proteins in colon tissue was significantly upregulated. In total, 82 serum and 70 colon components were identified following oral administration, while colonic administration yielded 73 serum and 78 colon components. Correlation analysis screened 36 active components associated with colonic administration and 25 with oral administration. Network pharmacology and molecular docking suggested that core components from colon administration (Anemoside B4, Betulonic acid) may act via targets such as EGFR, LCK, and MET, while oral components (Berberine, Oxyepiberberine) may target AURKA, MET, and PTGS2. SPR confirmed direct binding of anemoside B4 and berberine to EGFR with KD values of 9.47E-04 M and 2.96E-04 M, respectively. Western blot revealed route-dependent modulation of EGFR, PTGS2, LCK and AURKA expression, corroborating the predicted targeting.

CONCLUSION: BTWD is effective in treating UC through both colonic and oral administration. This study provides a comprehensive "efficacy-component-metabolism-target" analysis that reveals distinct pharmacological mechanisms underlying each administration route. These findings support the traditional use of BTWD and offer a theoretical foundation for developing optimized, route-specific therapies for UC.