Biotransformation of ginsenosides Rb(1), Rg(3 )and Rh(2 )in rat gastrointestinal tracts

BACKGROUND: Ginsenosides such as Rb(1), Rg(3 )and Rh(2 )are major bioactive components of Panax ginseng. This in vivo study investigates the metabolic pathways of ginsenosides Rb(1), Rg(3 )and Rh(2 )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 Rb(1), six metabolites of Rg(3 )and three metabolites of Rh(2 )were detected in the feces samples of the rats. Rh(2 )was a metabolite of Rb(1 )and Rg(3), whereas Rg(3 )was a metabolite of Rb(1). 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.