Protective effects of sinomenine against dextran sulfate sodium-induced ulcerative colitis in rats via alteration of HO-1/Nrf2 and inflammatory pathway

Background Dextran Sulfate Sodium (DSS) induces ulcerative colitis (UC), a type of inflammatory bowel disease (IBD) that leads to inflammation, swelling, and ulcers in the large intestine. The aim of this experimental study is to examine how sinomenine, a plant-derived alkaloid, can prevent or reduce the damage caused by DSS in the colon and rectum of rats. Material and methods Induction of ulcerative colitis (UC) in rats was achieved by orally administering a 2% Dextran Sulfate Sodium (DSS) solution, while the rats concurrently received oral administrations of sinomenine and sulfasalazine. The food, water intake was estimated. The body weight, disease activity index (DAI), colon length and spleen index estimated. Antioxidant, cytokines, inflammatory parameters and mRNA expression were estimated. The composition of gut microbiota was analyzed at both the phylum and genus levels in the fecal samples obtained from all groups of rats. Results Sinomenine treatment enhanced the body weight, colon length and reduced the DAI, spleen index. Sinomenine treatment remarkably suppressed the level of NO, MPO, ICAM-1, and VCAM-1 along with alteration of antioxidant parameters such as SOD, CAT, GPx, GR and MDA. Sinomenine treatment also decreased the cytokines like TNF-alpha, IL-1, IL-1 beta, IL-6, IL-10, IL-17, IL-18 in the serum and colon tissue; inflammatory parameters viz., PAF, COX-2, PGE(2), iNOS, NF-kappa B; matrix metalloproteinases level such as MMP-1 and MMP-2. Sinomenine significantly (P < 0.001) enhanced the level of HO-1 and Nrf(2). Sinomenine altered the mRNA expression of RIP1, RIP3, DRP3, NLRP3, IL-1 beta, caspase-1 and IL-18. Sinomenine remarkably altered the relative abundance of gut microbiota like firmicutes, Bacteroidetes, F/B ratio, Verrucomicrobia, and Actinobacteria. Conclusion The results clearly indicate that sinomenine demonstrated a protective effect against DSS-induced inflammation, potentially through the modulation of inflammatory pathways and gut microbiota.