Biol. Pharm. Bull. 28(4) 652—656 (2005)

aceae) is frequently taken orally, as a crude substance, as a traditional medicine in Asian countries. The major components of ginseng are ginsenosides, which contain an aglycone with a dammarane skeleton. These ginsenosides have been reported to exhibit various biological activities, including anti-inflammatory action and antitumor effects (inhibition of tumor-induced angiogenesis and the prevention of tumor invasion and metastasis). The pharmacological actions of these ginsenosides have been explained by their biotransformation by human intestinal bacteria. For example, protopanaxadiol ginsenosides are transformed to 20-O-b-D-glucopyranosyl-20(S)-protopanaxadiol (compound K) by human intestinal bacteria. The metabolite compound K induces an antimetastatic or anticarcinogenic effect by blocking tumor invasion or preventing chromosomal aberration and tumorigenesis. Ginsenosides Re and Rg1 are also transformed to ginsenoside Rh1 or 20(S)-protopanaxatriol, which have exhibited potent antiallergic and antiinflammatory effects. However, the antiiflammatory effect of protopanaxadiol ginsenosides, such as ginsenoside Rb1, and compound K, has not been studied. Therefore, we isolated ginsenoside Rb1 from ginseng and its metabolite compound K and investigated the antiinflammatory effect of ginsenoside Rb1 and its metabolite compound K (Fig. 1), using RAW264.7 cell induced by lipopolysaccharide (LPS).