1. State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, P. R. China
2. University of Chinese Academy of Sciences, Beijing 100049, P. R. China
3. Department of Chemistry, College of Sciences, Shanghai University, Shanghai 200444, P. R. China
4. Department of Microbiology, Sichuan Primed Bio-Tech Group Co., Ltd., Chengdu, Sichuan Province 610041, P. R. China