Metabolite profiling of ginsenoside Re in rat urine and faeces after oral administration

Following oral administration of ginsenoside Re, the compound and its metabolites were identified and quantified in rat urine and faeces by liquid chromatography coupled with triple quadrupole mass spectrometry (LC-MS/MS). Ginsenoside Re (200 mg/kg) was orally administered to rats by gastric intubation, and urine and faeces samples were then collected during the next 24 h using metabolic cages. Samples were prepared by solid phase extraction and analysed by LC-MS/MS. The precursor-product ion pairs used for LC-MS/MS analysis were: m/z 945→475 for ginsenoside Re, 799→637 for ginsenoside Rg1, 783→475 for ginsenoside Rg2, 637→475 for ginsenosides Rh1 and F1, 475→391 for protopanaxatriol, and 779→641 for digoxin (internal standard). The major ginsenosides excreted in urine were ginsenosides Re and Rg1, and only minimal amounts of ginsenosides Rg2 and Rh1 were found. Greater amounts of ginsenoside metabolites were detected in the faeces samples; biotransformation to ginsenoside Rg1 was predominant but further deglycosylated metabolites including ginsenoside F1 and protopanaxatriol were additionally detected. The total recovery of ginsenosides over 24 h was approximately 46%.