The free radicals and reactive oxygen species (ROS) generated by microsomal metabolism may augment an oxidative stress by the formation of hydrogen peroxide or superoxide anions in human beings. Accumulating proofs indicate that free radicals or active oxygen species would assault on important biological molecules such as DNA, protein, or lipid leading to many degenerative dis-ease conditions, such as cancer, gastric ulcers, Alzheimer’s, arthritis and ischemic reperfusion. For example, ROS make both nuclear DNA and mitochondrial DNA susceptible to damage and muta-genesis, and mutations in these two DNA pools were reported to lead to oxidative stress and both aging and carcinogenesis. Indeed, increased mutations in DNA have been observed in cancer cells of various tissue origins. Fortunately, human normal cells possess antioxidant system, viz. enzyme-mediated system, such as superoxide dismutase, catalase, glutathione peroxidase, and non-enzymatic factors, glutathione, ascorbic acid (Vitamin C), a-tocopherol (Vitamin E) to protect them against the oxidative stress and consecutive lipid peroxidation.