Dual benefits of Xiao Chai Hu Tang and its active compounds in CPT-11 therapy: intestinal protection via barrier restoration and anti-inflammation combined with enhanced tumor apoptosis

Ethnopharmacological relevance Xiao Chai Hu Tang (XCHT) is a classic Chinese herbal formula traditionally used for gastrointestinal disorders. Although XCHT alleviates irinotecan (CPT-11)-induced diarrhea, whether it confers the dual benefit of concurrently reducing intestinal toxicity and enhancing antitumor apoptosis remains unknown. Aim of the study To determine whether XCHT confers dual benefits in CPT-11-treated colorectal cancer (CRC), elucidate the underlying mechanisms, and identify the active constituents responsible. Materials and methods A DMH/DSS-induced CRC rat model was established to evaluate XCHT in CPT-11 therapy. Intestinal barrier integrity, inflammation, and tumor apoptosis were assessed. Effects were validated in SN-38-treated NCM-460 (barrier protection, anti-inflammation) and HCT-116 cells (synergistic apoptosis). Systemically absorbed constituents were identified by HPLC-Q-Orbitrap MS and functionally validated. Results XCHT mitigated CPT-11-induced toxicity in CRC rats by restoring tight junction proteins (ZO-1, occludin) and suppressing NLRP3 inflammasome-mediated inflammation (IL-1β, IL-18, IL-6, TNF-α), with these effects recapitulated in SN-38-treated NCM-460 cells. XCHT also enhanced CPT-11-induced apoptosis in tumor tissues and synergized with SN-38 in HCT-116 cells, as evidenced by increased Bax/Bcl-2 ratio. Among 17 systemically absorbed compounds, baicalein, baicalin, and wogonin were identified as key contributors to barrier protection and anti-inflammation, while baicalein and isoliquiritin were associated with the synergistic pro-apoptotic effect with SN-38 in functional screening. Conclusion XCHT improves CPT-11's therapeutic index by protecting intestinal barrier, suppressing NLRP3 inflammasome, and enhancing tumor apoptosis through distinct bioactive constituents. These findings provide a pharmacochemical and mechanistic foundation for its adjunctive use in CRC treatment.