Ginseng (the roots of Panax ginseng C. A. Meyer) is a well-known oriental crude drug and has been used as a tonic for enhancing body strength, recovering physical balance and stimulating metabolic function. A number of saponins called ginsenosides have been isolated,1 and are regarded as the main biological active principles of ginseng. Ginseng saponins are classified into three groups according to their chemical structures: protopanaxadiol, protopanaxatriol and oleanolic acid. The majority of saponins existing in the vegetable kingdom are of the oleanane family, while ginseng saponin is known to be of the triterpenoid saponin, a family of dammarane, which is rarely seen in other herbs.
Recently, many studies on absorption, distribution and excretion of ginsenosides (the biologically active ingredients of ginseng) after oral administration have been reported. Studies conducted especially on the metabolites of ginseng saponins show various pharmacological activities in vivo as well as in vitro - the inhibition of tumor growth and invasion, the reversal of multidrug-resistance in tumors and bacteria, and the prevention of tumor metastasis - which were undertaken by some researchers using acids, enzymes and intestinal bacteria.
Han et al. examined the decomposition products of ginsenosides Rb1, Re, and Rg1 using 0.1N HCl,9 while Kanaoka et al. investigated the metabolism of ginsenosides Rb1 and Rg1 by human intestinal flora. According to these studies, actual physiological effects in the human body arise from the metabolites of ginsenosides as well as compound K (20-O-β-D-glucopyranosyl-20(S)-protopanaxadiol) produced by gastric acid and intestinal bacteria etc.
However, thus far in cosmetic formulations, ginsenosides have only been used as an extract from ginseng and contain other undefined components, and the biological activity of each ginsenoside in the skin was not completely understood.