Metabolic Profiling of Panax notoginseng Saponins in Rat Feces Under Colitis by UHPLC-QTOF-MS/MS

The biotransformation of Panax notoginseng saponins (PNS) is pertinent to the effect of colitis mediated by gut microbiota, which has variant microbes and diversities in inflammatory bowel diseases (IBDs). However, the metabolic profiles of PNS mediated by gut microbiota are ambiguous under the pathological condition in vivo. Therefore, it is meaningful to explore the metabolic profiling of PNS mediated by gut microbiota under colitis in vivo. In this study, an ultrahigh performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (UHPLC-QTOF-MS/MS) method was employed to identify, and relatively quantify PNS and metabolites in rat feces with dextran sulfate sodium salt-induced colitis. The results showed that 89 metabolites were identified in the control group, whereas only 39 ones were detected in the colitis model group, indicating a significant reduction in Panax notoginseng saponin metabolites in the model group, particularly in deglycosylated products. Several main metabolites, such as ginsenoside Rb₁, ginsenoside compound K, protopanaxatriol, and protopanaxadiol, were generated with relatively low yields in the colitis group. Simultaneously, the deglycosylation reactions as the main biotransformation pathways mediated by gut microbiota of PNS were significantly limited in the colitis group. The employed analytical method helpfully demonstrated that gut microbiota dysbiosis in colitis was associated with the metabolism variation of PNS in vivo.