Biotransformation of ginsenosides Rb1, Rg3 and Rh2 in rat gastrointestinal tracts

BACKGROUND Ginsenosides such as Rb1, Rg3 and Rh2 are major bioactive components of Panax ginseng. This in vivo study investigates the metabolic pathways of ginsenosides Rb1, Rg3 and Rh2 orally administered to rats. METHODS High performance liquid chromatography-mass spectrometry (LC-MS) and tandem mass spectrometry (MS-MS) techniques, particularly liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS), were used to identify the metabolites. RESULTS Six metabolites of Rb1, six metabolites of Rg3 and three metabolites of Rh2 were detected in the feces samples of the rats. Rh2 was a metabolite of Rb1 and Rg3, whereas Rg3 was a metabolite of Rb1. Some metabolites such as protopanaxadiol and monooxygenated protopanaxadiol are metabolites of all three ginsenosides. CONCLUSION Oxygenation and deglycosylation are two major metabolic pathways of the ginsenosides in rat gastrointestinal tracts.