Effect of ethyl gallate and propyl gallate on dextran sulfate sodium (DSS)-induced ulcerative colitis in C57BL/6 J mice: preventive and protective

Objective and design Inflammatory bowel disease (IBD) is an idiopathic inflammatory condition of the digestive system marked by oxidative stress, leukocyte infiltration, and elevation of inflammatory mediators. In this study, we demonstrate the protective effect of ethyl gallate (EG), a phytochemical, and propyl gallate (PG), an anti-oxidant, given through normal drinking water (DW) and copper water (CW) in various combinations, which had a positive effect on the amelioration of DSS-induced ulcerative colitis in C57BL/6 J mice. Materials and methods We successfully determined the levels of proinflammatory cytokines and anti-oxidant enzymes by ELISA, tracked oxidative/nitrosative stress (RO/NS) by in vivo imaging (IVIS) using L-012 chemiluminescent probe, disease activity index (DAI), and histopathological and morphometric analysis of colon in DSS-induced colitis in a model. Results The results revealed that oral administration of ethyl gallate and propyl gallate at a dose of 50 mg/kg considerably reduced the severity of colitis and improved both macroscopic and microscopic clinical symptoms. The level of proinflammatory cytokines (TNF-α, IL-6, IL-1β, and IFN-γ) in colonic tissue was considerably reduced in the DSS + EG-treated and DSS + PG-treated groups, compared to the DSS alone-treated group. IVIS imaging of animals from the DSS + EG and DSS + PG-treated groups showed a highly significant decrease in RO/NS species relative to the DSS control group, with the exception of the DSS + PG/CW and DSS + EG + PG/CW-treated groups. We also observed lower levels of myeloperoxidase (MPO), nitric oxide (NO), and lipid peroxidation (LPO), and restored levels of GST and superoxide dismutase (SOD) in DSS + EG-DW/CW, DSS + PG/DW, and DSS + EG + PG/DW groups compared to DSS alone-treated group. In addition, we showed that the EG, PG, and EG + PG treatment significantly reduced the DAI score, and counteracted the body weight loss and colon shortening in mice compared to DSS alone-treated group. In this 21-day study, mice were treated daily with test substances and were challenged to DSS from day-8 to 14. Conclusion Our study highlights the protective effect of ethyl gallate and propyl gallate in various combinations which, in pre-clinical animals, serve as an anti-inflammatory drug against the severe form of colitis, indicating its potential for the treatment of IBD in humans. In addition, propyl gallate was investigated for the first time in this study for its anti-colitogenic effect with normal drinking water and reduced effect with copper water. Graphical Abstract