Chem. Pharm. Bull. 53(2) 177—179 (2005)

the best-known Chinese traditional herbal medicines, which has been used as a tonic, sedative, antifatigue, or anti-gastric ulcer drug for thousands of years. Naturally occurring ginsenosides, isolated from ginseng, have been regarded as the principal components responsible for the pharmaceutical and biological activities of ginseng. There are more than 30 different known naturally occurring ginsenosides, which can be classified into two groups according to their sapogenins with a dammarane skeleton, the protopanaxadiol and protopanaxatriol groups, except for ginsenoside R0. In most cases, Ginseng has been used as an orally administered crude drug. It has been reported that some naturally occurring ginsenosides abundant in ginseng, such as Rb1, Rb2 and Rg1, are water soluble and their absorption from the intestines is very poor. However, the intestinal bacterial metabolites of ginseng saponins can easily be absorbed from the intestine and are considered as primary active ingredients. There are many studies showing that the intestinal bacterial metabolites of 20(S)-protopanaxadiol-type (dioltype) ginsenosides, such as compound K (C-K), compound Y (C-Y) and ginsenoside Mc (G-Mc), exhibited excellent antitumor activities and were responsible for the main pharmacological activities of Ginseng. The previous studies on the intestinal bacterial metabolites of ginsenosides suggested that the pathway of ginsenoside metabolism by intestinal bacteria begins with the attack to sugar moieties at the position C-20 and ends with the attack to sugar moieties at the position C-3, and one of the major terminal products of this pathway is C-K. However, we found a new kind of snailase with special properties, which may hydrolyze sugar moieties at the position C-3 of ginsenosides firstly. Thus, in order to clarify additional active components of Ginseng, we studied on other metabolites of ginsenosides, using the enzyme. As the results, a novel metabolite was isolated and characterized. In this paper, we report the preparation, structural elucidation and activity in reversing the doxocubicin, or adriamycin (ADM), resistance of the metabolite from ginsenoside Rb3 with glycosidase hydrolysis.