Characterization of oxygenated metabolites of ginsenoside Rb1 in plasma and urine of rat.

Oxygenated metabolites have been suggested as the major circulating metabolites of ginsenosides. In the current study, 10 oxygenated metabolites of ginsenoside Rb1 in plasma and urine of rat following iv dose were characterized by comparison with chemically synthesized authentic compounds as quinquenoside L16 (M1 and M2), notoginsenoside A (M3), ginsenoside V (M4 and M7), epoxyginsenoside Rb1 (M5 and M9), notoginsenoside K (M6), and notoginsenoside C (M8 and M10), 9 of which were detected as in vivo metabolites for the first time. After oral administration of ginsenoside Rb1, M3, M4, and M7 were observed as major circulating metabolites and presented in the bloodstream of rat for 24 h. Characterization of the exact chemical structures of these circulating metabolites could contribute greatly to our understanding of chemical exposure of ginsenosides after consumption of ginseng products and provide valuable information for explaining multiple bioactivities of ginseng products.