1. Department of Medicinal Chemistry, School of Pharmacy, Fudan University, 138 Yixueyuan Road, Shanghai 200032, P. R. China, Department of Pharmacology, Institute of Medical Sciences, Shanghai JiaoTong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, P. R. China, and School of Pharmacy, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, P. R. China