Exploring the mechanism of Phyllanthus urinaria L. against ulcerative colitis based on network pharmacology and in vivo experiments

Objective: This study aims to explore the therapeutic effect and molecular mechanism of the aqueous extract of Phyllanthus urinaria L . (PUL) on ulcerative colitis (UC). Method: PUL was administered to UC mice induced by 2.25 % DSS. The changes of body weight, disease activity index (DAI) score and colon length were recorded during the experiment. Hematoxylin and eosin (HE) staining was conducted for pathology analysis of the mice in each group. The contents of inflammatory cytokines in colon tissues were detected by Elisa. Additionally, ultra performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-TOF-MS/MS) method was employed to identify the main components of PUL. Then, the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) database was utilized to explore the potential active ingredients and drug targets of PUL. The matching of drug targets and disease targets yielded cross targets, which were used to construct a protein-protein interaction (PPI) network in String. Key targets underwent Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. Finally, Western blotting was performed to verify the key proteins expressions in the predicted pathway of network pharmacology and the expressions of tight junction proteins in the colon tissue. Result: PUL has been found to effectively alleviate the symptoms such as weight loss, bloody stools, and colon shortening in mice with UC. Administration of PUL led to an increase in tight junction protein in the colonic tissue of mice, as compared to the model group. Elisa results revealed that PUL reduced the expression of pro- inflammatory factors in mice with UC. HE staining results show that PUL can alleviate colon tissue damage caused by UC. A total of 773 components were detected in the water extract of PUL, among which 26 components, including quercetin, epigallocatechin gallate and kaempferol, may possess anti-UC activity. Network pharmacology analysis suggested that PUL may play an anti-UC role by inhibiting tumor necrosis factor (TNF) pathway. Finally, Western blotting results confirmed that the PUL inhibited the TNF pathway and effectively treated UC. Conclusion: These preliminary research results indicate that PUL has the potential to exhibit anti-inflammatory activity by inhibiting the TNF pathway, thereby alleviating symptoms associated with UC. Substances such as quercetin, epigallocatechin gallate and kaempferol in PUL are believed to play an important role in this process.