Isolation of Ginsenoside Ra1-Hydrolyzing Bacteria from Human Intestinal Microflora Bacterial strains pre- viously isolated from the fresh feces of a healthy Korean man

lism of unabsorbable dietary components and in the enterohepatic circulation of endogenous and exogenous substances. The metabolism of ginsenosides from ginseng by human intestinal bacteria has been studied to learn the biological action of these components. Ginseng (the root of Panax ginseng C.A. MEYER, Araliaceae) is frequently used as a crude substance and taken orally in China, Korea, Japan, and other Asian countries as a traditional medicine. The major components of ginseng are ginsenosides, which are glycosides containing an aglycone with a dammarane skeleton. To express the pharmacological actions of these ginsenosides, it is thought that ginseng saponins must be metabolized by human intestinal bacteria after they are orally administered. For example, ginsenosides Rb1, Rb2, and Rc are transformed to 20-O-b-Dglucopyranosyl-20(S)-protopanaxadiol (compound K) by human intestinal bacteria. Compound K induces an antimetastatic or anticarcinogenic effect by blocking tumor invasion or preventing chromosomal aberration and tumorigenesis. Related to the biotransformation of ginsenosides, Hasegawa et al. and Bae et al. isolated Prevotella oris, Fusobacterium K-60 and Bacteroides HJ-15, from human intestinal feces. Park et al. purified ginsenoside Rb1-metabolizing b-glucosidase from Fusobacterium K-60. However, the purification and characterization of b-D-xylosidase (EC 3.2.1.37) from intestinal bacteria related to the metabolism of ginsenosides has not been studied. Therefore, we attempted to purify and characterize ginsenoside Ra-hydrolyzing b-D-xylosidase from Bifidobacterium breve K-110 (Chart 1), which was isolated as a ginsenoside-hydrolyzing intestinal bacterium from human intestinal feces.