This study was done to evaluate the antioxidant activity of Pueraria lobata. Pueraria is known as kudzu in Japan and gegen in China. This study was done on diabetic rats. The chemicals included puerarin (and variants,) daidzin, genistin, daidzein and genistein. The rats were given pueraria roots (500 mg/kg extract) containing 50 mg/kg puerarin, the main isoflavone in Pueraria. The rats received a coenzyme Q(9) supplementation, also.
Oxidative stress is associated with atherosclerosis, diabetes and cancer. Malondialdehyde (MDA) levels of the blood are a measure of the oxidative damage to tissues. It is a measure of lipid peroxidation. Much of the oxidative stress comes from the oxidation of glucose. Reactive oxygen species are produced by enzymes, such as NO synthase and xanthine oxidase. Use of plant phenolic antioxidants, such as puerarin, can reduce oxidative damage.
The present study used dried roots of Pueraria lobata. The main puerarin related phenols were hydroxypuerarin, puerarin, methoxypuerarin and xylosylpuerarin. Diabetes was induced in a group of male rats. Oxidation was allowed to develop for 7 weeks before puerarin treatment was started. Some rats were treated with puerarin and some were not (controls.)
The kudzu dose of 500 mg/kg/day corresponds to a dose of about 50 mg/kg/day of puerarin for body weight per day. One group received alpha-tocopherol (vitamin E) as a ‘control’ for comparison.
After 3 weeks of treatment the animals were examined. All stressed animals lost body weight, including those treated with puerarin and those treated with alpha-tocopherol. There was a marked reduction in oxidative stress (as measured by MDA) in animals treated with either puerarin or alpha-tocopherol.
CONCLUSION: Puerarin and alpha-tocopherol were shown to have a strong effect in reducing oxidative stress in live animals. No toxicity was found. Puerarin may be useful to treat oxidative stress in cancer, atherosclerosis and diabetes mellitus.