Carthamin yellow alleviates dextran sodium sulfate-induced ulcerative colitis by repairing the intestinal barrier and activating the Nrf2/GPX4 axis.

Ulcerative colitis (UC) is a chronic and recurrent inflammatory bowel disease (IBD). There is a growing prevalence of UC, but current conventional drugs lack efficacy. Carthamin yellow (CY) is a flavonoid compound extracted from safflower that is widely used and has various pharmacological effects. In the present study, we established colitis models in mice via DSS and in Caco-2 cells via lipopolysaccharide (LPS). Our results showed that CY treatment attenuated the symptoms of colitis by decreasing colonic pathological damage and improving disease activity index (DAI) scores. Notably, we observed that CY treatment decreased the levels of proinflammatory cytokines (TNF-α, IL-6, and IL-1β) by inhibiting the NLRP3/Caspase-1/IL-1β and MAPK/NF-κB signaling pathways. Moreover, we verified that treatment with CY obviously improved intestinal barrier function in both DSS-induced mice and LPS-stimulated Caco-2 cells. Ferroptosis-related markers were assessed. CY attenuated DSS-induced colitis by inhibiting ferroptosis, as assessed by Fe accumulation, total antioxidant capacity (T-AOC), and reactive oxygen species (ROS), 4-hydroxynonenal (4-HNE), and glutathione (GSH) levels. Additionally, there was an increase in superoxide dismutase (SOD) and catalase (CAT) activity, as well as alterations in ferroptosis-related protein and gene expression (ACSL4, GPX4, SLC7A11, TfR1, and FTH1). Further analyses revealed that CY could inhibit ferroptosis via the Nrf2/GPX4 axis in both in vivo and RSL3-induced Caco-2 cell models. Importantly, the antiferroptotic and protective effects of CY were nullified by Nrf2 knockout in vivo and by the use of ML385 in vitro. In conclusion, the effects of CY on UC are strongly associated with the Nrf2 pathway. CY might be a potential candidate for the treatment of UC. Therefore, our results provide an important reference for investigating the mechanisms of flavonoid compounds involved in preventing inflammatory diseases.