Preventative Effects of Ginkgo biloba Extract (EGb761) on High Glucose-Cultured Opacity of Rat Lens Qian Lu, 1,2† Tingting Yang, 2† Mingzhu Zhang, 2 Lei Du, 2 Ling Liu, 2 Nan Zhang, 2 Hao Guo, 2 Fan Zhang, 2 Gang Hu 1 * and Xiaoxing Yin 1,2 * 1 Jiangsu Key Laboratory of Neurodegeneration, Department of Pharmacology, Nanjing Medical University, Nanjing, 210029, China 2 Laboratory of New Drugs and Clinical Application, Xuzhou Medical College, Xuzhou, 221004, China Diabetic cataract is one of the earliest secondary complications of diabetes, and it is characterized by opacification of the eye lens. In this study, we examined the protective effects of Ginkgo biloba extract (EGb761) on rat lenses cultured in high-glucose conditions. The cultured rat lenses were divided into six groups: normal group, high-glucose group, high glucose plus low, medium, and high concentrations of EGb761 groups, and a high glucose plus bendazac lysine group. The activities of antioxidases, aldose reductase, advanced glycosylation end products, transforming growth factor-β2, Smad2/3, E-cadherin, and α-smooth muscle actin were assessed by different methods. Compared with the levels in the high glucose group, EGb761 decreased the intensity of oxidative stress, decreased aldose reductase activation and the level of advanced glycosylation end products, and suppress the transforming growth factor-β2 or Smad pathway activation, further increase the expression of E-cadherin and decrease α-smooth muscle actin, and therefore, prevents the pathological changes of high glucose-induced lens epithelial cells and ameliorated lens opacity. These results suggest that EGb761 has protective effects on several pharmacological targets in the progress of diabetic cataract and is a potential drug for the prevention of diabetic cataract. Copyright © 2013 John Wiley & Sons, Ltd. Keywords: Ginkgo biloba extract; lens opacity; high glucose; oxidative stress; TGF-β2. INTRODUCTION Hyperglycemia is the key initiating factor in the develop- ment of diabetes mellitus, and involved in the pathogenesis of diabetic complications affecting the kidneys, nerves, blood vessels, and eyes. Diabetic cataract is one of the earliest secondary complications of diabetes, leading to loss of vision. It is characterized by opacification of the eye lens that interferes with transmission of light onto the retina (Pollreisz and Schmidt–Erfurth, 2010). The mechanism underlying the pathogenesis of cataractogenesis is not completely understood. Many scholars consider the progression of diabetic cataract as a result of the interaction of multiple factors, such as polyol pathway, advanced glycation end products (AGEs), and oxidative stress. Oxidative stress is well recognized as a key mechanism in the pathogenesis of diabetic complications (Brownlee, 2005). Transforming growth factor-β (TGF-β) has been identified as a critical regulator in pathophysiological processes of ocular tissue development or repair. Our previous studies confirmed that high glucose-induced reactive oxygen species (ROS) increases the level of TGF-β (Lu et al., 2013). Inappropriate TGF-β signaling in the anterior lens epithelial cells results in an epithelial- mesenchymal transition (EMT) that bears morphological and molecular resemblance to forms of cataract, including anterior subcapsularand posterior capsule opacification (de Iongh et al., 2005). Numerous in vitro and in vivo studies indicate that this TGF-β-induced EMT in lens epithelial cells is characterized by induced expression of numerous extracellular matrix proteins (laminin, collagens I, III, and fibronectin), intermediate filaments (desmin and α-smooth muscle actin [α-SMA]), as well as, the loss of epithelial genes (α-crystallin and E-cadherin) (de Iongh et al., 2005; Cho and Yoo, 2007). Because of complexity of the mechanisms involved, there are no definitive drugs to delay the development of diabetic cataract. Therefore, it is necessary to develop new drugs for diabetic cataract that can deal with more than one pharma- cological target in this intricate mechanism. Ginkgo biloba extract is a standard extract from the leaves of Ginkgo biloba containing 24% ginkgo-flavone glycosides (e.g., kaempferol, quercetin, and isorhamnetin derivatives) and 6% terpenoid (e.g., ginkgolides A, B, C, and J and bilobalide) (Liu et al., 2012). It has been used to treat cardiovascular and neurological disorders in recent years. However, there are still few published reports that focus on the protection of EGb761 on diabetic cataract. Therefore, it is worthwhile to explore its potential effects on preventing the progression of diabetic cataract. In the present work, the possible influence of EGb761 on the lens opacification and the parameters that indi- cate protective effects against the progress of diabetic cataract, such as antioxidase activities, the level of AGEs, aldose reductase (AR) activity, the expression * Correspondence to: Xiao-Xing Yin, Department of Clinical Pharmacology, School of Pharmacy, Xuzhou Medical College, Xuzhou, Jiangsu 221004, China; Gang Hu, Department of Pharmacology, Nanjing Medical University, Nanjing, 210029, China. E-mail: yinxx@xzmc.edu.cn (Xiao-Xing Yin); ghu@njmu.edu.cn (Gang Hu) † These authors contributed equally to this work. PHYTOTHERAPY RESEARCH Phytother. Res. 28: 767–773 (2014) Published online 2 September 2013 in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/ptr.5060 Copyright © 2013 John Wiley & Sons, Ltd. Received 30 March 2013 Revised 09 July 2013 Accepted 29 July 2013