Diosmetin has therapeutic efficacy in colitis regulating gut microbiota, inflammation, and oxidative stress via the circ-Sirt1/Sirt1 axis

• Published in: Acta pharmacologica Sinica Vol. 43; no. 4; pp. 919 - 932
• Main Authors: Li, Hai-long, Wei, Yi-ying, Li, Xiao-he, Zhang, Shan-shan, Zhang, Ruo-tong, Li, Jin-he, Ma, Bo-wei, Shao, Shuai-bo, Lv, Zi-wei, Ruan, Hao, Zhou, Hong-gang, Yang, Cheng
• Format: Journal Article
• Language: English
• Published: Singapore Springer Singapore 01.04.2022; Nature Publishing Group
• Subjects: Animal models; Animals; Biomedical and Life Sciences; Biomedicine; Body weight; Caco-2 Cells; Colitis; Colitis - chemically induced; Colitis - drug therapy; Colitis - metabolism; Colon; Colon - metabolism; Cyanobacteria; Cyclooxygenase-2; Dextran; Dextran sulfate; Dextran Sulfate - toxicity; Digestive system; Disease Models, Animal; Drinking water; Flavonoids; Flavonoids - metabolism; Flavonoids - pharmacology; Flavonoids - therapeutic use; Gastrointestinal Microbiome; Gastrointestinal tract; Humans; IL-1β; Immunology; Inflammation - metabolism; Inflammatory bowel disease; Inflammatory bowel diseases; Interleukin 6; Internal Medicine; Intestinal microflora; Lipopolysaccharides; Medical Microbiology; Mice; Mice, Inbred C57BL; Microbiota; Mitochondria; NF-κB protein; Oxidative Stress; Pharmacology/Toxicology; Reactive oxygen species; Signal transduction; SIRT1 protein; Sirtuin 1 - metabolism; Tumor necrosis factor-α; Vaccine; Zonula occludens-1 protein; proinflammatory cytokines; colitis; inflammatory bowel disease; oxidative stress; gut microbiota; diosmetin
• ISSN: 1671-4083; 1745-7254
• DOI: 10.1038/s41401-021-00726-0

Diosmetin (3',5,7 -trihydroxy-4'-methoxy flavone) is a natural flavonoid compound in the citrus species, it exhibits a variety of pharmacological activities, but little is known of its effects on colitis. In this study we evaluated the therapeutic effects of diosmetin on mouse models of chronic and acute colitis. Chronic colitis was induced in mice by drinking water containing 3% dextran sulfate sodium (DSS) from D0 to D8, followed by administration of diosmetin (25, 50 mg · kg −1  · d −1 ) for another 8 days. Acute colitis was induced by drinking water containing 5% DSS from D0 to D7, the mice concomitantly received diosmetin (25, 50 mg · kg −1  · d −1 ) from D1 to D7. During the experiments, body weight and disease activity index (DAI) were assessed daily. After the mice were sacrificed, colon tissue and feces samples were collected, and colon length was measured. We showed that in both models, diosmetin administration significantly decreased DAI score and ameliorated microscopic colon tissue damage; increased the expression of tight junction proteins (occludin, claudin-1, and zonula occludens-1), and reduced the secretion of proinflammatory cytokines IL-1β, IL-6, TNF-α, and Cox-2 in colon tissue. We found that diosmetin administration remarkably inhibited colon oxidative damage by adjusting the levels of intracellular and mitochondrial reactive oxygen species, GSH-Px, SOD, MDA and GSH in colon tissue. The protection of diosmetin against intestinal epithelial barrier damage and oxidative stress were also observed in LPS-treated Caco-2 and IEC-6 cells in vitro. Furthermore, we demonstrated that diosmetin markedly increased the expression of Nrf2 and HO-1 and reduced the ratio of acetylated NF-κB and NF-κB by activating the circ-Sirt1/Sirt1 axis, which inhibited oxidative stress and inflammation in vivo and in vitro. Diosmetin reversed the effects of si-circSirt1 and si-Sirt1 in LPS-treated Caco-2 and IEC-6 cells. When the gut microbiota was analyzed in the mouse model of colitis, we found that diosmetin administration modulated the abundance of Bacteroidetes, Actinobacteria, Cyanobacteria and Firmicutes, which were crucial for inflammatory bowel disease. Our results have linked colitis to the circ-Sirt1/Sirt1 signaling pathway, which is activated by diosmetin. The results imply that diosmetin may be a novel candidate to alleviate DSS-induced colitis and can be a lead compound for future optimization and modification.