Carrier-free self-assembled berberine–gallic acid nanorods ameliorate ulcerative colitis by inhibiting ferroptosis via regulation of the ACSL4/GPX4 Axis

Abstract Ulcerative colitis (UC) is a chronic relapsing inflammatory bowel disease with limited therapeutic options. Here, we report carrier-free nanoparticles (BG NPs) rationally assembled from berberine (BBR) and gallic acid (GA)—two natural products whose pharmacological activities target distinct pathological features of UC. BG NPs exhibited a uniform rod-like morphology and maintained colloidal stability under simulated gastrointestinal conditions. In a DSS-induced murine colitis model, orally administered BG NPs outperformed 5-aminosalicylic acid in reducing the disease activity index, restoring colon length, and preserving intestinal barrier integrity by upregulating the tight junction proteins Occludin and ZO-1. Mechanistically, BG NPs inhibited ferroptosis by upregulating GPX4 and downregulating ACSL4 at the transcriptional level, accompanied by reduced Fe²⁺, lipid ROS, and 4-HNE accumulation, and simultaneously suppressed NF-κB-driven inflammation by blocking p65 nuclear translocation. In vitro, BG NPs protected colonic epithelial cells from DSS-induced oxidative stress at non-cytotoxic concentrations, restored glutathione levels, and preserved mitochondrial membrane potential, with efficacy comparable to the antioxidant N-acetylcysteine while exhibiting ferroptosis pathway regulation that NAC lacks. No organ toxicity was detected at therapeutic doses. These findings establish BG NPs as a safe oral nanotherapeutic that concurrently targets ferroptosis and NF-κB-mediated inflammation in UC and illustrate a design-driven strategy for constructing natural product-based nanomedicines. Graphical abstract