Ginsenoside Re of Panax ginseng possesses significant antioxidant and antihyperlipidemic efficacies in streptozotocin-induced diabetic rats William C.S. Cho a, ⁎ , Wai-Shing Chung a , Sally K.W. Lee a , Albert W.N. Leung b , Christopher H.K. Cheng c , Kevin K.M. Yue a a School of Chinese Medicine, Hong Kong Baptist University, 7 Baptist University Road, Hong Kong, China b School of Chinese Medicine and Health Care, Chinese University of Hong Kong - Tung Wah Community College, Hong Kong, China c Department of Biochemistry, Chinese University of Hong Kong, Hong Kong, China Received 30 June 2006; received in revised form 24 August 2006; accepted 28 August 2006 Available online 8 September 2006 Abstract Diabetes mellitus is characterized by hyperglycemia and complications affecting the eye, kidney, nerve and blood vessel. We have previously demonstrated the occurrence of oxidative stress of streptozotocin-induced diabetic rats, preceded by a depletion in the tissue level of glutathione. In this study, when diabetic rats were treated with ginsenoside Re of Panax ginseng C.A. Meyer, there was a significant reduction in blood glucose, total cholesterol and triglyceride levels. On the other hand, oxidative stress has been implicated in the pathogenesis of diabetes and its complications. It was found that treatment by ginsenoside Re restored the levels of both glutathione and malondialdehyde in the eye and kidney to those found in the control rats. This is the first report demonstrating ginsenoside Re has significant antioxidant efficacy in diabetes, and prevents the onset of oxidative stress in some vascular tissues. Our results demonstrated that ginsenoside Re could lower blood glucose and lipid levels, and exerts protective actions against the occurrence of oxidative stress in the eye and kidney of diabetic rats. Our data also provide evidence that ginsenoside Re could be used as an effective antidiabetic agent particularly in the prevention of diabetic microvasculopathy. © 2006 Elsevier B.V. All rights reserved. Keywords: Diabetes mellitus; Ginsenoside Re; Panax ginseng; Antihyperglycemia; Antihyperlipidemia; Antioxidant 1. Introduction Diabetes mellitus is the most common endocrine disorder characterized by hyperglycemia and long-term complications affecting the eye, kidney, nerve and blood vessel. Panax ginseng C. A. Meyer (ginseng) has been widely used to treat diabetes in traditional Chinese medicine (Cho et al., 2005; Covington, 2001). Results of clinical studies demonstrated that ginseng could improve the immune response in diabetic patients (Kiefer and Pantuso, 2003). In most cases, it is the root of ginseng that is used to treat diabetes. Recent reports found that the berry extract of ginseng could also be used to treat diabetes in obese mice (Attele et al., 2002; Dey et al., 2002, 2003; Xie et al., 2002), and the beneficial effects could be attributed to ginsenoside Re (Attele et al., 2002; Xie et al., 2005). However, the mechanism of actions of ginsenoside Re remains to be elucidated. In this study, the action of ginsenoside Re on serum glucose, cholesterol and triglyceride of streptozotocin-induced diabetic rats was studied. This natural compound was also assessed of its ability to prevent the occurrence of oxidative stress in the vascular tissues of diabetic rats. 2. Materials and methods 2.1. Chemicals Streptozotocin was obtained from Sigma Chemical Co (St Louis, MO, USA). Ginsenoside Re of high performance liquid chromatography grade with purity N 99% was obtained from Hongjiu Ginseng (Jilin, PR China). The chemical structure of ginsenoside Re is shown in Fig. 1. Unless otherwise stated, all chemicals are of analytical grade. European Journal of Pharmacology 550 (2006) 173 – 179 www.elsevier.com/locate/ejphar ⁎ Corresponding author. Tel.: +852 2958 5441; fax: +852 2958 5455. E-mail address: williamcscho@gmail.com (W.C.S. Cho). 0014-2999/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.ejphar.2006.08.056