Metabolic and pharmacokinetic differences of Huai Hua san in Sprague Dawley and ulcerative colitis rats.

Huai Hua San (HHS), a traditional Chinese medicine (TCM) originated from the "Pu Ji Ben Shi Fang," is primarily used to treat conditions such as colitis and hemorrhoids. Despite its demonstrated therapeutic effects on Ulcerative Colitis (UC), the metabolic characteristics in vivo and the mechanisms of action of bioactive components remain unclear. This study systematically investigated the metabolic differences of HHS in normal and UC model rats and explored the association between these variations and the pharmacological effects of key flavonoid components, providing a theoretical basis for further research into its chemical basis and mechanisms of action. The UHPLC-Orbitrap-MS/MS was performed to character the prototype and metabolites, and UPLC-MS/MS was used to elucidate the pharmacokinetic profiles of five main compounds of HHS in rats. Furthermore, we compared the differences of absorption and metabolism between normal and UC rats. Based on the comparison with reference substances, retention times, accurate masses, and characteristic MS/MS fragment patterns, a total of 181 and 167 HHS prototypes and metabolites were inferred in the normal and model groups. Sankey diagram visualization revealed a significant decrease in plasma flavonoid prototype compounds within the UC model group, accompanied by an increased abundance of flavonoid metabolites in urine. This suggests that intestinal absorption efficiency or enterohepatic circulation may be influenced by the inflammatory microenvironment. Further analysis indicated that metabolic pathways of flavonoid compounds, such as glucuronidation, sulfation, and methylation, were altered in UC rats. Furthermore, this investigation delved into the in vivo exposure profiles of five core flavonoid components in HHS (quercetin, naringenin, hesperetin, luteolin, and genistein). The results revealed that naringenin and hesperetin exhibited relatively higher exposure levels, while UC model rats displayed significantly enhanced quercetin absorption rates and markedly increased systemic exposure of genistein. Collectively, this study uncovers alterations in metabolic profiles and changes of pharmacokinetic behavior of HHS under UC pathological conditions, elucidating the dynamic metabolism-exposure-efficacy interrelationships of flavonoid components. These findings provide a theoretical basis for further research on the relationship between the chemical constituents of HHS and its pharmacological mechanisms of action.