Integrated metabolomics and network pharmacology revealed the key active ingredients for the treatment of ulcerative colitis in the Citrus reticulata 'Dahongpao' peel.

Citrus reticulata pericarpium (CRP), the peel of Citrus reticulata 'Dahongpao' (DHP) is a medicinal herb with significant therapeutic value for treating ulcerative colitis (UC). However, the active therapeutic components of CRP are unclear. This study aims to reveal the metabolites potentially associated with the pharmacological properties of CRP. We performed flavonoid-targeting metabolomics to characterize the components of CRP (anti-UC part), tangerine pith and Citrus reticulata semen (no anti-UC effects parts) of DHP and further screened active components of CRP using network pharmacology and molecular docking. Lipopolysaccharide (LPS)-stimulated RAW 264.7 cells were used to study the anti-inflammatory effect of the selected biologically active components. The therapeutic effects of the selected components were further investigated in a mouse model of UC induced by DSS. Three compounds, namely nobiletin, sinensetin, and hispidulin had the lowest docking scores among all screened ingredients. IL-6 and NO concentrations were significantly decreased in the LPS-stimulated RAW264.7 cells compared with control cells treated with these compounds. Moreover, UC mice treated with these compounds showed a reversal in weight loss, inhibition of shortening of colon length, and amelioration of colon injury. Our results indicated that sinensetin, nobiletin, and hispidulin can be potentially used for the treatment of UC.