Abstract: According to this invention, Prevotella sp. S-1 strain (Bacteroidaceae family, KFCC-10923) is cultured in a medium supplemented with Panax ginseng saponin so as to collect the metabolites of saponin generated and accumulated in the medium, thus ensuring their selective production with high efficiency.This invention related to a process for the preparation of the metabolites of protopanaxadiol saponin, wherein Prevotella sp. S-1 strain (Bacteroidaceae family, KFCC-10923), is cultured at a medium supplemented with Panax ginseng saponin and then, the metabolites of protopanaxadiol saponin contained in the medium--20-O-.beta.-D-glucopyranosyl-20(s)-protopanaxadiol, 20-O-?.alpha.-L-arabinopyranosyl-20(s)-protopanaxadiol, and 20-0-?.alpha.-L-arabinopuranosyl(1.fwdarw.6)-.beta.-D-glucopyranosyl!-20(s )-protopanaxadiol --are generated and accumulated for collecting them thereof.

Abstract: This invention relates to ginsenoside Mc with formula (I), ##STR1## an intestinal flora metabolite of ginseng saponin and anticancer agent containing it as an active ingredient. In addition to a novel compound, the anticancer agent of this invention consists of one active ingredient elected from compound K, compound Y or 20(S)-protopanaxatriol, intestinal flora metabolites of ginseng saponin, together with one or more pharmaceutically acceptable carriers. Said agent is a novel type of potential anticancer agent since it has immunopotentiating actions including inhibitory actions on the vascularization of tumors and extravasation of cancer cells.