Abstract: AIM:To investigate the protective effects of 18-glycyrrhetinic acid(GA) on lipopolysaccharide(LPS)-induced injury in the intestinal epithelial cell line(IEC-6).METHODS:IEC-6 cells were treated by LPS(100 gmL-1) with or without GA(0.1,1.0 or 10 molL-1) for 24 h.The inflammatory cytokines in the cultured medium,TNF- and IL-6,were measured by ELISA.The supernatant nitric oxide(NO) production was detected by nitrite assay.Reactive oxygen species(ROS) were estimated by flow cytometry.Epithelial tight junction was determined by transepithelial resistance(TER),and protein levels were measured by Western blotting.RESULTS:With GA treatment,LPS-stimulated TNF- and IL-6 were inhibited,ROS and NO were decreased,the transepithelial permeability was recovered,ZO-1(tight junction related protein) was reversed,the protein level of cyclooxygenase-2(COX-2) was down-regulated,and 15-hydroxyprostaglandin dehydrogenase(PGDH) was up-regulated.CONCLUSIONS:These results suggest that GA has the protective capacity to attenuate LPS-induced injury in intestinal epithelial cells and protect the epithelial tight junction.The underlying mechanism was related to a decrease in proinflammatory factor and regulating COX-2 and PGDH.