title: Studies on absorption, distribution, excretion and metabolism of ginseng saponins. VI. The decomposition products of ginsenoside Rb2 in the stomach of rats.
abstract: The decomposition of ginsenoside Rb2 (Rb2) in rat stomach (in vivo) and in 0.1 N HCl solution (in vitro) was investigated in detail. By treating with 0.1 N HCl, the acidity of which is similar to that of gastric juice, a part of Rb2 was hydrolyzed to 20(R,S)-ginsenoside Rg3. On the other hand, Rb2 was little decomposed in rat stomach and a small quantity of an unidentified metabolite, which was different from the hydrolyzed products in 0.1 N HCl, was observed. The metabolite was separated into four compounds, which were identified by 1H- and 13C-nuclear magnetic resonance and fast atom bombardment mass spectrometry. These compounds were determined to be 25-hydroxy-23-ene (IV), 24-hydroxy-25-ene (V), 25-hydroperoxy-23-ene (VI) and 24-hydroperoxy-25-ene (VII) derivative of Rb2, respectively. In this study, it is suggested that 20(S)-protopanaxatriol saponins undergo hydrolysis of the C-20 glycosyl moiety and hydration of the side chain, on the other hand, 20(S)-protopanaxadiol saponins undergo oxygenation of the side chain.
authors.affiliation: School of Pharmaceutical Sciences, University of Shizuoka, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Karikura
authors.forename: T
authors.initials: T
authors.lastname: Miyase
authors.forename: H
authors.initials: H
authors.lastname: Tanizawa
authors.forename: T
authors.initials: T
authors.lastname: Taniyama
authors.forename: Y
authors.initials: Y
authors.lastname: Takino
mesh_terms: D000042:Absorption; D000818:Animals; D001711:Biotransformation; D005753:Gastric Mucosa / Q000378:metabolism*; D036145:Ginsenosides; D051381:Rats; D012503:Saponins / Q000378:metabolism / Q000493:pharmacokinetics*; D014018:Tissue Distribution
chemical_list: D036145:Ginsenosides; D012503:Saponins; C048026:ginsenoside Rb2