Objective To elucidate the material basis of Quzhou Chenpi (Citri Reticulatae Pericarpium) extract (CPE) and to investigate its mechanism in improving functional dyspepsia (FD) by repairing the intestinal barrier. Methods CPE was prepared by water decoction combined with freeze-drying. Qualitative and quantitative analyses of its chemical components were performed using ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) and high-performance liquid chromatography (HPLC), followed by network pharmacology to predict potential targets and pathways. In vivo, an FD rat model was established by iodoacetamide combined with irregular feeding. After drug intervention, gastric emptying rate and small intestinal propulsion rate were measured. Histopathological changes in the stomach and duodenum were examined by hematoxylin-eosin staining. Levels of lipopolysaccharide (LPS), diamine oxidase (DAO) in serum as well as tumor necrosis factor-α (TNF-α) in duodenal tissue were determined by ELISA. The expressions of zonula occludens-1 (ZO-1) and Occludin in duodenal tissue was assessed by immunohistochemistry. In vitro, a TNF-α-induced Caco-2 intestinal barrier injury model was used. Transepithelial electrical resistance (TEER) value and fluorescein isothiocyanate-dextran with relative molecular mass 4 × 10⁴ (FD-4) permeability were measured. The distribution of ZO-1 and Occludin proteins was observed by immunofluorescence staining. The mRNA expressions of ZO-1, Occludin, interleukin-6 (IL-6) and TNF-α were detected by qRT-PCR. IL-6 secretion was measured by ELISA. The phosphorylation levels of cellular Src (c-Src) and protein kinase B (Akt) were detected by Western blotting. Results A total of 84 chemical components were identified from CPE, eight of which were reported in Citri Reticulatae Pericarpium for the first time. The contents of the four major flavonoids were ranked from high to low as hesperidin > narirutin > nobiletin > tangeretin. Network pharmacology predicted that the potential core targets of CPE for improving FD involved SRC, AKT1, etc., with enrichment in phosphoinositide 3-kinase (PI3K)/Akt signaling pathway and tight junction regulation. In vivo, CPE significantly ameliorated gastrointestinal motility disorders in FD rats (P < 0.05, 0.01, 0.001), alleviated duodenal mucosal injury, reduced levels of LPS and DAO in serum (P < 0.01, 0.001), suppressed TNF-α protein and mRNA expressions in duodenal tissue (P < 0.01, 0.001), and up-regulated Occludin protein expression (P < 0.05, 0.001). In vitro, the actual hesperidin content in CPE was only 10.48% of that in the hesperidin monomer group, yet CPE was equivalent to hesperidin monomer in stabilizing TEER and reducing FD-4 permeability (P < 0.01, 0.001). CPE significantly up-regulated the mRNA expressions of ZO-1 and Occludin (P < 0.001), maintained their continuous network-like distribution, significantly inhibited IL-6 transcription and secretion (P < 0.01, 0.001), and significantly reduced the values of p-c-Src/c-Src and p-Akt/Akt (P < 0.05). Conclusion CPE significantly ameliorates gastrointestinal motility disorders and duodenal mucosal barrier injury in FD rats, and alleviates barrier dysfunction and inflammation in TNF-α-induced Caco-2 cells. Its effect depends on the inhibition of over-activation of c-Src/Akt signaling pathway. The overall efficacy demonstrates the multi-component synergistic characteristics of traditional Chinese medicine, providing an experimental basis for the application of Quzhou Citri Reticulatae Pericarpium in gastrointestinal diseases.

Quzhou Citri Reticulatae Pericarpium  /  functional dyspepsia  /  Caco-2 cells  /  intestinal barrier injury  /  tight junction  /  inflammation  /  c-Src/Akt signaling pathway  /  narirutin  /  hesperidin  /  nobiletin  /  tangeretin