1. Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, 1 Xian Nong Tan Street, Beijing 100050, P. R. China, National Institute for the Control of Pharmaceutical and Biological Products, 2 Tiantanxili, 100050, P. R. China, and Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 555 Zu Chong-zhi Road, Shanghai 201203, P. R. China