摘要Background:Around the world,there is a high incidence of gastric ulcers.YS,an extract from the Chinese herb Albizzia chinensis (Osbeck) Merr,has potential thera-peutic applications for gastrointestinal diseases.Here we elucidated the protective effect and underlying mechanism of action of YS on gastric ulcer in rats injured by ethanol.Methods:The ethanol-induced gastric ulcer rat model was used to assess the pro-tective effect of YS.A pathological examination of gastric tissue was performed by H&E staining.GES-1 cells damaged by hydrogen peroxide were used to simu-late oxidative damage in gastric mucosal epithelial cells.Endogenous NRF2 was knocked down using small interfering RNA.Immunoprecipitation was used to detect ubiquitination of NRF2.Co-immunoprecipitation was used to detect the NRF2-Keap1 interaction.Results:YS (10 and 30 mg/kg,i.g.) significantly reduced the ulcer index,decreased MDA level,and increased SOD and GSH levels in gastric tissues damaged by ethanol.YS promoted NRF2 translocation from cytoplasm to nucleus and enhanced the NQO1 and HO-1 expression levels in injured rat gastric tissue.In addition,YS regulated NQO1 and HO-1 via NRF2 in H2O2 -induced oxidative injured GES-1 cells.Further studies on the underlying mechanism indicated that YS reduced the interaction between NRF2 and Keap1 and decreased ubiquitylation of NRF2,thereby increasing its stability and expression of downstream factors.NRF2 knockdown abolished the effect of YS on MDA and SOD in GES-1 cells treated with H2O2.Conclusion:YS reduced the NRF2-Keap1 interaction,promoting NRF2 transloca-tion into the nucleus,which increasing the transcription and translation of NQO1 and HO-1 and improved the antioxidant capacity of rat stomach.