Indigo Naturalis regulates the gut microbiota to increase SCFAs content and improve ulcerative colitis lesions

Background The global prevalence of ulcerative colitis (UC) is approximately 5 million, and the incidence is on the rise. The gut microbiota (GM) plays a key role in the pathogenesis and progression of UC. Studies have found that Indigo Naturalis (abbreviated as Indan) and Indigo can regulate GM to improve UC, but the mechanism has not been elucidated. Materials and methods Using 16S rDNA to examine GM changes and evaluate the effects of Indan/Indigo treatment on short-chain fatty acids (SCFAs). Results The community structure of GM, there is a significant difference between the UC group and the control group. Among them, the abundance of the Proteobacteria phylum increases in the UC group, while the abundance of the Firmicutes phylum decreases. The dynamic balance between Lachnospiraceae_unclassified and Escherichia is a key factor in the pathogenesis of UC. Indan and indigo (Principal components of Indan) can alter the abundance and structure of GM. Indan and indigo increase the abundance of beneficial bacteria, leading to an increase in SCFAs content. Compared with indigo, Indan has a stronger effect on increasing the content of SCFAs. Indan can significantly increase the abundance of Clostridium_sensu_stricto_1 , produce hexanoic acid. It is worth noting that the proportion regulation of Indan and indigo on the microbial structure of different phenotypes is also a new mechanism for the treatment of UC. Conclusion Indan/Indigo regulates GM abundance and structure, enhances SCFAs content, inhibits inflammatory response, promotes ulcer healing, restores intestinal wall integrity, and treats UC.