Studies on Absorption, Distribution, Excretion and Metabolism of Ginseng Saponins. VII. Comparison of the Decomposition Modes of Ginsenoside-Rb1 and -Rb2 in the Digestive Tract of Rats

• Published in: Chemical & pharmaceutical bulletin Vol. 39; no. 9; pp. 2357 - 2361
• Main Authors: KARIKURA, Masami, MIYASE, Toshio, TANIZAWA, Hisayuki, TANIYAMA, Toshio, TAKINO, Yoshio
• Format: Journal Article
• Language: English
• Published: Tokyo The Pharmaceutical Society of Japan 1991; Maruzen; Japan Science and Technology Agency
• Subjects: Animals; Biological and medical sciences; C-NMR; decomposition mode; Digestive System - metabolism; FAB-MS; General pharmacology; ginsenoside prosapogenin; ginsenoside Rb1; ginsenoside Rb2; Ginsenosides; HPLC; hydroperoxide; Intestinal Absorption; Medical sciences; Panax - metabolism; Pharmacognosy. Homeopathy. Health food; Pharmacology. Drug treatments; Plants, Medicinal; rat gastrointestinal tract; Rats; Saponins - metabolism; Saponins - pharmacokinetics; Tissue Distribution; TLC; Rat; Digestive system; Pharmacognosy; Rodentia; Metabolism; Panax ginseng; Medicinal plant; Saponin; Vertebrata; Mammalia; Dicotyledones; Animal; Angiospermae; Spermatophyta; Degradation product; Araliaceae
• ISSN: 0009-2363; 1347-5223
• DOI: 10.1248/cpb.39.2357

In order to clarify some similarities and differences of decomposition modes between 20(S)-protopanaxadiol (20(S)-ppd) saponins, represented by ginsenoside Rb1 (Rb1) and ginsenoside Rb2 (Rb2), the devompositions of Rb1 and Rb2 in the rat gastrointestinal tract, 0.1 N NCl and crude hesperidinase were investigated in detail. As in the case of Rb2 reported previously, Rb1 was hydrolyzed to 20(R, S)-ginsenoside Rg3 in 0.1 N HCl. On the other hand, hydroperoxidation of Rb1 occurred in rat stomach; the major hydroperoxide was separated and identifed as the 25-hydroperoxy-23-ene derivative of Rb1 (VIII) by 1H- and 13C-nuclear magnetic resonance and fast atom bombardment mass spectrometry. The decomposition modes of 20(S)-ppd saponins (Rb1 and Rb2) differed from that of 20(S)-protopanaxatriol saponin (Rg1) in rat stomach. In rat large intestine, five decomposition products of Rb1 were observed by thin-layer chromatography, and these were identified as gypenoside XVII (G-XVII), ginesenoside Rd (Rd), ginsenoside F2 (F2), compound K (C-K) and VIII. The decomposition modes of Rb1 and Rb2, both 20(S)-ppd saponins, are considered to be different because of the hydrolysis rate in the terminal sugar moiety at the C-20 hydroxyl group in the rat large intestine. Using crude hesperidinase, Rb1 was decomposed to G-XVII, F2 and C-K, and Rb2 was decomposed to 3-O-β-D-glucopyranosyl-20-O-[α-L-arabinopyranosyl(1→6)-β-D-glucopyranosyl]-20(S)-ppd, F2 and C-K. Consequently, it appears that hydrolysis by β-glucosidase, which is present in the rat large intestine, is distinct from that by crude hesperidinase. Tetracycline-resistant bacteria decomposed both Rb1 and Rb2 to their respective prosapogenins, except for Rd, and their respective hydroperoxides, while Rd and hydroperoxides of Rb1 and Rb2 were produced by enteric enzymes.