Differential antioxidant and quinone reductase inducing activity of American, Asian, and Siberian ginseng

The antioxidant and quinone reductase (QR) inducing activities of American, Asian, and Siberian ginseng have been reported using various plant materials, solvents, and assays. To directly establish their comparative bioactivity, the effects of extracts obtained from acidified methanol (MeOH), a gastrointestinal mimic (GI), and hexane (Hex) on free radical scavenging and QR induction were tested. Siberian ginseng-MeOH had the highest total phenolic content at 52.6 μmol gallic acid equivalents/g. GI liberated ⩾50% more phenolics than MeOH and Hex from American and Asian ginseng. Siberian ginseng-Hex was most effective at inducing QR activity in Hepa1c1c7 cells. GI and MeOH extracts of American and Asian ginseng exhibited comparable HOCl scavenging activity, but were ⩾4.6-fold more potent than Siberian ginseng. Siberian ginseng was the most effective scavenger of ONOO−. Siberian-MeOH had the highest ferric reducing antioxidant power (FRAP), and American ginseng-GI had the highest oxygen radical absorbance capacity (ORAC). Thus, the components in ginseng have antioxidant and QR-inducing activity which are dependent upon the dose, method of extraction, radical species, and plant species.