The chemical constituents and metabolite profiles of Huangqin decoction in normal and ulcerative colitis rats by UHPLC-Q-TOF/MS analysis

Ulcerative colitis (UC) is a recurrent and palliative inflammatory bowel disease (IBD) begins in distal colon and spreads proximally to the entire colon, characterized by mucosal inflammation which reduces patients' quality of life and increases the risk of bowel cancer. Huangqin decoction (HQD), a classical Chinese formula recorded in Treatise on Febrile Diseases has been widely used for the treatment of UC. Studies found that HQD has good curative effect on UC. However, the chemical constituents and metabolites of it has not been fully elucidated due to lack of in vitro and in vivo studies, which also limits the pathogenesis study and clinical application of UC. In this study, a rapid and high-throughput UHPLC-Q-TOF/MS method was established and applied to analyse the chemical constituents and metabolites of HQD. Besides, we established an UC rat model and compared the differences of metabolite profiles between normal and UC rats both in plasma and urine. A total of 139 constituents were chemically defined or tentatively identified, including 98 flavonoids, 10 triterpene saponins, 10 monoterpene glycosides, 4 phenols, 5 phenylethanoid glycosides and 12 other types of compounds. A total of 175 and 147 HQD-related xenobiotics were detected in normal and UC rats, respectively. The main metabolic pathways of HQD were methylation, hydrolysis, hydroxylation, glucuronidation and sulfation. The holistic metabolic profiles of HQD revealed that normal and UC rats had certain differences in drug absorption and metabolism. This study can provide references for the follow-up study of HQD, and provide essential data for the further study of the relationships between chemical constituents and pharmacological activities of HQD.