Metabolic profiling of Gegen-Qinlian Decoction and its modified formula in gut microbiota from healthy individuals and ulcerative colitis patients with different syndromes using UHPLC-QTOF-MS/MS and an in vitro incubation model.

The efficacy of Gegen-Qinlian Decoction (GQD) and its modified formula (MGQD) against ulcerative colitis (UC) with damp-heat syndrome (UC-DHS) is closely linked to gut microbiota-mediated biotransformation. Using UHPLC-QTOF-MS/MS, this study profiled GQD and MGQD in artificial gastrointestinal fluids (AGF) and after incubation with gut microbiota from healthy individuals (HI) and UC patients with spleen deficiency syndrome (UC-SDS) and UC patients with UC-DHS. A custom-built MS data analysis workflow was developed to characterize the metabolic profiles of GQD and MGQD. The profiles comprised metabolized prototype constituents, metabolites, pathways, and metabolic rates. The results showed that GQD/MGQD remained stable in AGF. The HI, UC-SDS, and UC-DHS gut microbiota metabolized 52/60, 39/43, and 35/35 GQD/MGQD prototype compounds, resulting in 25 (GQD) and 28 (MGQD) metabolites common to all groups. All three groups exhibited similar metabolic pathways, predominantly deglycosylation to produce aglycones. However, the HI group demonstrated the highest metabolic capability, followed by UC-SDS and then UC-DHS, with superior metabolic rates, lower residual compounds, and higher metabolite abundance. Notably, the addition of two herbs to MGQD did not alter the core metabolic pathways of GQD-sourced constituents but inhibited the biotransformation of certain constituents. Further analysis revealed that glycoside metabolic rates depended on structural features: flavonoid glycosides were metabolized fastest, followed by phenylethanoid glycosides and saponins; among sugar moieties, glucosides were fastest, followed by glucuronides, xylosides, arabinosides, and apiosides. This study reveals the metabolic profiles of GQD/MGQD across different gut microbiota groups (HI, UC-SDS, UC-DHS) and provides a practical analytical workflow for herb-microbiota interaction research.