Induction of chemoprotective phase 2 enzymes by ginseng and its components.

Phase 2 detoxification enzymes protect against carcinogenesis and oxidative stress. Ginseng (Panax spp.) extracts and components were assayed for inducer activity of NQO1 (quinone reductase), a phase 2 enzyme, in Hepalc1c7 cells. Ginseng extracts were analyzed for ginsenosides and panaxytriol. Korean red Panax ginseng extracts demonstrated the most potent phase 2 enzyme induction activity (76900 U/g dried rhizome powder and 27800 U/g for two similar preparations). The ginsenoside-enriched HT-1001 American ginseng (Panax quinquefolius) extract was the next most potent inducer, with activity of 15900 U/g, followed by raw American ginseng root with activity of 8700 U/g. Neither a polysaccharide-enriched extract of American ginseng nor a commercial white Panax ginseng preparation showed any inducer activity. Pure ginsenosides showed no inducer activity. Protopanaxadiol and protopanaxatriol, deglycosylated ginsenoside metabolic derivatives, showed potent induction activity (approximately 500000 U/g each). Synthetic panaxytriol was over 10-fold more potent (induction potency 5760000 U/g). There was no correlation between ginsenoside content and phase 2 enzyme induction. The most potent inducing red ginseng extract also had the highest panaxytriol content, 120.8 mu g/g. We found that ginseng induced NQO1 and that polyacetylenes are the most active components.