1. State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing 100083, People's Republic of China, Institute of Materia Medica, Chinese Academy of Medical Sciences, Beijing 100050, People's Republic of China, Ocean University of China, Qingdao 266003, People's Republic of China, and Institute of Pharmaceutical Biology, Heinrich-Heine University, Universitaetsstrasse 1, D-40225 Duesseldorf, Germany