1. Kekulé-Institute of Organic Chemistry and Biochemistry University of Bonn Gerhard-Domagk-Strasse 1 53121 Bonn Germany
2. State Key Laboratory of Drug Research Shanghai Institute of Materia Medica Chinese Academy of Sciences 555 Zu Chong Zhi Road, Zhangjiang Hi-Tech Park 201203 Shanghai China
3. University of Chinese Academy of Sciences No. 19A Yuquan Road Beijing 100049 China