Stereospecific antioxidant effects of ginsenoside Rg3 on oxidative stress induced by cyclophosphamide in mice.

Ginsenoside Rg3 is one of the active ingredients isolated from Panax ginseng C.A. Meyer. Previous investigation demonstrated that Rg3 was stereospecific in promotion of the immune response. The present study was designed to evaluate Rg3 and its epimers, 20(R)-Rg3 and 20(S)-Rg3, for their effects on oxidative stress induced by cyclophosphamide (Cy) in mice. Forty-eight mice were randomly distributed into 6 groups and intraperitoneally administered saline solution, Cy, 20(R)-Rg3, 20(S)-Rg3, 20(R)-Rg3+Cy or 20(S)-Rg3+Cy. After that, the spleen, thymus and serum were collected to measure the indices of the organs and oxidative parameters. The results showed that Rg3 significantly inhibited Cy-induced oxidative stress in mice by increasing the indices of the spleen and thymus and total antioxidant capacity, elevating the activities of catalase, superoxidase dismutase and lysozyme as well as decreasing the activity of xanthine oxidase and the levels of malondialdehyde and nitric oxide. Rg3 was stereospecific in antioxidant activities as R form exhibited significantly higher antioxidant effects than S form. Therefore, R form should be used when Rg3 is considered to be used as an antioxidant agent.