The present invention is directed to antioxidative and antiproliferative agents containing North American ginseng (proprietary extract HT1001) alone or in combination with Ginkgo biloba (GB), Saint John's Wort (SJW), ginkgolides, flavonoids, ginsenosides, hypericin, and/or hyperforin. The antioxidative and antiproliferative agents according to the present invention show significant inhibition of Fe.sup.2+-catalyzed lipid peroxidation and Fe.sup.2+ chelation activity, the ability to scavenge hydroxyl free radicals, the ability to reduce neuroblastoma cell numbers, and/or the ability to promote neurite outgrowth. These effects are consistent with the behavior of Fe.sup.2+ chelators and the variance in both type and magnitude of effects exerted by the chemical components suggests a synergistic mechanism of action.