1. Department of Basic Medicine, Wuxi Medical School Jiangnan University Wuxi Jiangsu 214122 P. R. China
2. State Key Laboratory of Natural Medicines China Pharmaceutical University No. 24 Tongjia Lane Nanjing 210009 P. R. China
3. Department of Pharmacology, Yong Loo Lin School of Medicine National University of Singapore Singapore 117600 Singapore