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BACKGROUND: Ulcerative colitis is a gastrointestinal disease closely related to intestinal epithelial barrier damage and intestinal microbiome imbalance; however, effective treatment methods are currently limited. Rehmannia glutinosa polysaccharide (RGP) is an important active ingredient with a wide range of pharmacological activities, although its protective effect on colitis remains to be explored. In the present study, we verified the in vitro anti‐inflammatory effect of RGP, and observed the ameliorating effect of RGP on dextran sulfate sodium‐induced colitis in mice. RESULTS: The results showed that (i) RGP attenuates lipopolysaccharide‐induced overexpression of inflammatory factors in RAW264.7 cells; (ii) RGP improves the pathological damage caused by DSS, including weight loss, increased disease activity index and intestinal tissue ulcers; (iii) RGP improves tight junction proteins to protects the tightness of the intestinal epithelium; (iv) RGP inhibits the expression of inflammatory factors through the nuclear factor‐kappa B pathway, and improved the of intestinal tissues inflammation; and (v) RGP can maintain the species diversity of intestinal microbes, increase the content of short‐chain fatty acids and then restore the imbalance of intestinal microecology. CONCLUSION: RGP can improve the intestinal microbiota to strengthen the intestinal epithelial barrier and protect against DSS‐induced colitis. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: Oleanolic acid (OA) is a pentacyclic triterpenoid compound that is present at high levels in olive oil and has several promising pharmacological effects, such as liver protection and anti‐inflammatory, antioxidant, and anticancer effects. The purpose of the present study was to assess whether OA treatment affects gut health compared to a control condition, including gut microbiota and intestinal epithelial immunity. RESULTS: Illumina MiSeq sequencing (16S rRNA gene) was used to investigate the effect of OA on the microbial community of the intestinal tract, while Illumina HiSeq (RNA‐seq) technology was used to investigate the regulatory effect of OA on gene expression in intestinal epithelial cells, which allowed for a comprehensive analysis of the effects of OA on intestinal health. The results showed that the consumption of OA initially controlled weight gain in mice and altered the composition of the gut microbiota. At the phylum level, OA significantly increased the relative abundances of cecum Firmicutes but decreased the abundance of Actinobacteria, and at the genus level it increased the relative abundance of potentially beneficial bacteria such as Oscillibacter and Ruminiclostridium 9. Oleanolic acid treatment also altered the expression of 12 genes involved in the Kyoto Encyclopedia of Genes and Genomes（KEGG）pathways of complement and coagulation cascades, hematopoietic cell lineage, and leukocyte transendothelial migration in intestinal epithelial cells to improve gut immunity. CONCLUSION: Intake of OA can contribute beneficial effects by optimizing gut microbiota and altering the immune function of intestinal epithelial cells, potentially to improve intestinal health status. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]