Hepatoprotective effect of ginsenoside Rb1 and compound K on tert-butyl hydroperoxide-induced liver injury

Background/Aim: The main component of Panax ginseng, which have been reported by many researchers, are ginsenoside Rb1, Rb2 and Rc. Orally administered ginsenosides are metabolized to 20-O-beta-D-glucopyranosyl-20(S)-protopanaxadiol (compound K) by intestinal bacteria and absorbed to blood. To understand its hepatoprotective effect and its mechanism, the effects of ginsenoside Rb1 and its metabolite compound K on chemically injured HepG2 cells and mice were investigated. Methods: Ginsenoside Rb1 and compound K were isolated from ginseng. Hepatotoxicity of HepG2 cells and mice was induced by tert-butyl hydroperoxide (t-BHP). Cytotoxicity for HepG2 cells and serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) for mice as markers of hepatoprotective activity were measured. Results: Compound K protected HepG2 cell cytotoxicity induced by t-BHP. However, ginsenoside Rb1 did not inhibit cytotoxicity. Nevertheless, both ginsenoside Rb1 and compound K significantly inhibited the increment of ALT and AST induced by t-BHP in mice, when it was orally administered. However, intraperitoneally administered ginsenoside Rb1 did not inhibit the increment of plasma ALT and AST induced by t-BHP in mice. These compounds did not exhibit antioxidant activity. However, compound K showed the potent membrane stabilizing activity more than ginsenoside Rb1. Conclusion: Compound K, which was produced from ginsenosides of Panax ginseng in intestine, could protect liver injury.