Antioxidant and anti-inflammatory effects of Equisetum arvense L. on acid-induced ulcerative colitis in rats

Equisetum arvense L. (EAL) has a long history in traditional medicine for its ability to address various digestive and inflammatory conditions. Here, we aimed to evaluate the therapeutic potential of the EAL hydroalcoholic extract (HAEA) compared with the standard medications in a rat model of ulcerative colitis (UC) caused by acetic acid. Eighty-one male Sprague Dawley rats were acquired and randomly allocated into nine equal groups: healthy control group, negative control groups (receiving normal saline and carboxymethyl cellulose gel base), positive control groups (receiving asacol rectally and mesalazine orally), and test groups treated with different amounts of HAEA. At the end of the experiment (7 days), colonic injury was evaluated by macroscopic, biochemical, and stereological assessments. The effectiveness of HAEA on colonic tissue was proved by significantly decreasing the malondialdehyde (MDA) and interleukin-1β (IL-1β) concentrations as well as myeloperoxidase (MPO) activity and increasing the superoxide dismutase (SOD) activities and glutathione peroxidase (GPx) in comparison to negative control groups. Particularly, the HAEA gel 10% rectal enema was significantly effective in decreasing MDA and IL-1β, as well as increasing GPx and SOD activities in comparison to positive control groups (P < 0.05). According to the stereological evaluations, HAEA 600 mg/kg orally and gel 10% rectal enema-treated groups, as well as the positive control groups, had significantly higher epithelium, submucosa, and muscularis mucosa volume density in comparison to the negative control groups (P < 0.001). This study showed promising therapeutic effects in all HAEA-treated groups, particularly HAEA gel 10% rectal enema in the induced UC rat model compared to conventional treatments. Both in vivo and in vitro findings indicate that EAL has the potential to be used as an additive therapeutic strategy in UC patients.