Metabolic analysis of Panax notoginseng saponins with gut microbiota-mediated biotransformation by HPLC-DAD-Q-TOF-MS/MS

Saponins such as notoginsenosides and ginsenosides from Panax notoginseng are responsible for the herb's clinical applications. Unfortunately, there is poor oral bioavailability of saponins. However, gut microbiota can transform saponins to yield the metabolites that are potential bioactive substances. In this study, we aimed to characterize the metabolic profiles of P. notoginseng saponins (PNS) by incubating them with human gut microbiota. The notoginsenosides, ginsenosides and related metabolites were separated and identified using a highly sensitive and selective high-performance liquid chromatography coupled with diode array detection/quadrupole tandem time-of-flight mass spectrometry (HPLC-DAD-Q-TOF-MS/MS). The results showed that the most abundant metabolites, ginsenoside F1, protopanaxatriol (PPT), ginsenoside Rh2, ginsenoside compound K (GCK) and protopanaxadiol (PPD), were reported to possess stronger related pharmacological activities when compared with parent ginsenosides. These metabolites were identified among a total of 45 other metabolites. Furthermore, it was elucidated that deglycosylation is the main metabolic pathway which saponins are split off from glycosyl moieties by the enzymes secreted from gut microbiota. The gut microbiota may play a significant role in mediating the bioactivities of PNS.