Biotransformation and metabolic profile of American ginseng saponins with human intestinal microflora by liquid chromatography quadrupole time-of-flight mass spectrometry

American ginseng is a widely used natural product. Ginseng products are usually taken orally, and human intestinal microflora may metabolize ginsenosides. Existing publications report the metabolite fates of ginsenosides. However, investigations on the comprehensive metabolic profile of American ginseng extract are absent because of the chemical complexity and limitation of analytical methods. In this work, we studied the biotransformation and metabolic profile of American ginseng extract by human intestinal microflora. Human fecal microflora was prepared from a healthy Chinese man and then anaerobically incubated with American ginseng sample at 37 degrees C for 24h. A rapid and simple liquid-liquid extraction method was used for sample pretreatment. A highly sensitive and selective liquid chromatography/quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS) method was used to characterize ginsenosides and related metabolites in the reaction samples. The LC-Q-TOF-MS provides superior data quality and advanced analytical capabilities for profiling, identifying, and characterizing complex metabolites in matrix-based biological samples. A total of 25 metabolites were detected, 13 of which were undoubtedly assigned by comparison with reference compounds, and 12 others were tentatively identified. The three most abundant metabolites are 20S-ginsenoside Rg(3), ginsenoside F-2 and compound K. The main metabolic pathways of ginseng saponins are deglycosylation reactions by intestinal microflora through stepwise cleavage of sugar moieties. Subsequent dehydration reactions also occur. Protopanaxadiol- and oleanane-type triterpenoids are easy to metabolize. The intestinal microbiota may play an important role in mediating the metabolism bioactivity of American ginseng. (C) 2013 Elsevier B.V. All rights reserved.