[Protective effect of ethyl syringate against ulcerative colitis based on JAK2/STAT3 pathway]

To study the therapeutic effect and mechanisms of ethyl syringate(MD) on ulcerative colitis(UC), the MTT assay was used to detect the proliferation inhibition of RAW264.7 cells and HT-29 cells by different concentrations of MD(50, 100, 200, 400 μmol·L~(-1)). UC cell models were constructed by inducing RAW264.7 cells and HT-29 cells with lipopolysaccharide(LPS) and tumor necrosis factor-α(TNF-α). An animal model was established by inducing mice with 2.5% dextran sulfate sodium(DSS) to verify the therapeutic effect of MD on UC. A control group, a model group(LPS or TNF-α), and groups treated with different concentrations of MD(50, 100, 200, 400 μmol·L~(-1)) were set up in this study. Nitric oxide(NO) levels were measured using a NO detection kit. Intracellular reactive oxygen species(ROS) levels were assessed using a laser confocal microscope and ROS kit. Enzyme-linked immunosorbent assay(ELISA) was used to detect changes in the levels of interleukin-6(IL-6), TNF-α, interferon-γ(INF-γ), interleukin-10(IL-10), and myeloperoxidase(MPO) in cells and animal tissues. Western blot was used to detect the expression levels of phosphorylated Janus kinase 2(p-JAK2), Janus kinase 2(JAK2), phosphorylated signal transducer and activator of transcription 3(p-STAT3), signal transducer and activator of transcription 3(STAT3), zonula occludens-1(ZO-1), occludin, and claudin-1 in cells and animal tissues. The results showed that MD can improve the inflammatory response by inhibiting the production of NO and ROS and regulating the expression of inflammatory factors. It significantly reduced the disease activity index(DAI) in mice, improved the shortening of the colon, and repaired intestinal epithelial damage by inhibiting the activation of the JAK2/STAT3 pathway, thereby exerting anti-UC activity.