Magnolia biondii-Derived Exosome-Like Nanoparticles Ameliorate Ulcerative Colitis by Suppressing Inflammation,...

Ulcerative colitis (UC) is a chronic, relapsing inflammatory bowel disease with limited treatment options and suboptimal remission rates. Plant-derived exosome-like nanoparticles have emerged as promising therapeutic agents due to their natural origin, biocompatibility, and capacity to deliver bioactive cargo. This study aimed to isolate exosome-like nanoparticles from the decoction of Magnolia biondii flower buds (Xinyi) (MFELNs) and evaluate their therapeutic potential in a murine model of UC.

MFELNs were isolated from Xinyi decoction using differential centrifugation and ultracentrifugation. MFELNs were characterized by transmission electron microscopy, nanoparticle size and potential analysis, and metabolomic profiling. The in vitro antioxidant activity was assessed by DPPH scavenging and intracellular ROS suppression assays. Anti-inflammatory effects were evaluated in LPS-stimulated RAW 264.7 macrophages by measuring cytokine expression and macrophage polarization via flow cytometry. The promotion of cell migration was assessed in NIH3T3 cells by scratch assay. UC was induced in C57BL/6 mice using dextran sodium sulfate (DSS), and MFELNs were orally administered daily for 14 days. Disease activity index, colon length, histopathology, colonic cytokine expression, and gut microbiota composition were evaluated. Bioinformatics analysis, molecular docking, and Western blot were performed to elucidate the underlying molecular mechanisms.

MFELNs exhibited typical exosome-like morphology with a size of 66.7 ± 1.3 nm and a negative surface charge. Metabolomic profiling revealed enrichment in flavonoids, alkaloids, lignans, and phenolic acids. MFELNs demonstrated satisfactory biocompatibility and gastrointestinal stability. In vitro, MFELNs scavenged DPPH radicals, suppressed H₂O₂-induced ROS generation, downregulated LPS-induced pro-inflammatory cytokines (TNF-α, IL-1β, IL-6), restored IL-10 expression, and promoted macrophage polarization from M1 to M2 phenotype. In vivo, MFELNs attenuated DSS-induced body‑weight loss, reduced DAI scores, prevented colon shortening, and alleviated histopathological damage. MFELNs downregulated colonic pro-inflammatory cytokines and restored IL-10 expression. Gut microbiota analysis revealed that MFELNs restored the DSS-elevated Firmicutes/Bacteroidota ratio without significantly affecting α-diversity. Bioinformatics screening identified four potential bioactive components (sesamin, litsoeine/laurotetanine, demethylwedelolactone, and armepavine) that target SRC. Molecular docking demonstrated favorable binding between these components and SRC, while Western blot confirmed that MFELNs suppressed the SRC/NF-κB signaling pathway.

MFELNs represent a novel class of decoction-derived exosome-like nanoparticles that ameliorate UC through integrated anti-inflammatory, antioxidant, and microbiota-modulating mechanisms. Their therapeutic effects are mediated, at least in part, through suppression of the SRC/NF-κB signaling pathway. These findings position MFELNs as a promising natural nanotherapeutic strategy for UC and support the concept that self-assembled nanoparticles formed during herbal decoction constitute an important material basis for the efficacy of traditional Chinese herbals.