Combinatorial Metabolism Notably Affects Human Systemic Exposure to Ginsenosides from Orally Administered Extract of Panax notoginseng Roots (Sanqi)

Ginsenosides are medicinal ingredients of the cardiovascular herb Panax notoginseng roots (Sanqi). Here, we implemented a human study (ChiCTR-ONC-09000603; www.chictr.org) to characterize pharmacokinetics and metabolism of ginsenosides from an orally ingested Sanqi-extract (a 1:10 water extract of Sanqi) and the human plasma and urine samples were analyzed by liquid chromatography-mass spectrometry. Plasma and urinary compounds derived from ginsenosides included: 1) intestinally absorbed ginsenosides Ra₃, Rb₁, Rd, F₂, Rg₁, and notoginsenoside R₁; and 2) the deglycosylated products compound-K, 20(S)-protopanaxadiol, 20(S)-protopanaxatriol, and their oxidized metabolites. The systemic exposure levels of the first group compounds increased as the Sanqi-extract dose increased, but those of the second group compounds were dose-independent. The oxidized metabolites of 20(S)-protopanaxadiol and 20(S)-protopanaxatriol represented the major circulating forms of ginsenosides in the bloodstream, despite their large interindividual differences in exposure level. The metabolites were formed via combinatorial metabolism that consisted of a rate-limiting step of ginsenoside deglycosylation by the colonic microflora and a subsequent step of sapogenin oxidation by the enterohepatic cytochrome P450 enzymes. Significant accumulation of plasma ginsenosides and metabolites occurred in the human subjects receiving 3-week subchronic treatment with the Sanqi-extract. Plasma 20(S)-protopanaxadiol and 20(S)-protopanaxatriol could be used as pharmacokinetic markers to reflect the subjects' microbial activities, as well as the timely-changes and interindividual differences in plasma levels of their respective oxidized metabolites. The information gained from the current study is relevant to pharmacology and therapeutics of Sanqi.