Compound spleen-tonifying composition alleviates dextran sulfate sodium-induced ulcerative colitis in rats

Ulcerative colitis (UC) is a chronic relapsing inflammatory bowel disease with rising global incidence. Current therapies for UC often provide incomplete relief and are associated with adverse side effects, highlighting the need for alternatives with increased safety and effectiveness. Compound spleen-tonifying composition (CSTC) contains ingredients, such as Pulsatilla chinensis (Bunge) Regel and Glycyrrhiza uralensis Fisch, that have been shown to be efficacious in the treatment of UC. Its mechanism needs to be investigated further.

To study the therapeutic effect and mechanism of CSTC in dextran sulfate sodium (DSS)-induced UC in rats.

Sprague-Dawley rats were freely given 4% DSS solution for seven days to establish the UC model. After intervention with CSTC and its different solvent extracts, body weight changes, the disease activity index (DAI), and colon histopathology were assessed to evaluate therapeutic outcomes. The contents of superoxide dismutase (SOD), malondialdehyde (MDA), myeloperoxidase (MPO), glutathione peroxidase (GSH-px), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) in colon tissue were determined to investigate changes in biochemical indicators.

DSS administration triggered severe UC symptoms, including weight loss, colon shortening, elevated DAI scores, and histological damage. These symptoms were accompanied with oxidative stress (reduced SOD and GSH-px levels and increased MDA and MPO levels), inflammation (elevated TNF-α, IL-1β, and IL-6 levels), and a reduction in the expression levels of tight junction proteins [zonula occludens-1 (ZO-1) and occluding]. High- and medium-dose CSTC treatment significantly alleviated clinical symptoms, restored colon morphology, normalized oxidative stress markers, suppressed proinflammatory cytokines, and enhanced ZO-1 and occludin levels, demonstrating dose-dependent efficacy. Notably, solvent extraction critically influenced bioactivity: Nonpolar extracts (chloroform and petroleum ether) showed minimal effects, whereas polar extracts (ethyl acetate and n-butanol) remarkably improved clinical symptoms.

The above findings highlight CSTC's multifaceted anti-UC effects, which are mediated through oxidative stress mitigation and cytokine modulation, while emphasizing the polarity-dependent efficacy of its extracts.