Free radical scavenging capacity as related to antioxidant activity and ginsenoside composition of Asian and North American ginseng extracts

Different Panax species; derived from Asia (Panax ginseng C.A. Meyer) and N orth America (Panax quinquefolium L.) were extracted by methanol and evalua ted for relative ginsenoside composition and antioxidant activities. Ginsen g root contained a greater proportion of total ginsenoside compared to gins eng hair analyzed by high-performance liquid chromatography.; North America n ginseng root was characterized with undetectable ginsenoside Rf and great er Rb-1/Rb-2 than Asian ginseng root. Panax quinquefolium exhibited a relat ively higher (P < 0.05) affinity to scavenge free radical than panax ginsen g using the 2,2-azobis (3-ethylbenzothine-6-thine-6-surfonic acid) radical model. In a bilayer lamella suspension oxidation model induced by peroxyl r adicals, ginseng samples exhibited notable antioxidant activity. Specifical ly, however, the P. quinquefolium extracts delayed lipid peroxidation longe r (P < 0.05) than the P. ginseng extracts. Ginseng extracts from both Panax species protected human low-density lipoprotein against cupric ion-mediate d oxidation. Similar protection was observed against peroxyl radical-induce d supercoiled DNA breakage. A pure ginsenoside standard (e.g., Rb-1) produc ed similar results. The antioxidant activities of different ginseng species and specific plant parts include free radical scavenging and may be relate d to ginsenoside Rb-1/Rb-2 content.