1. School of Life Sciences, Beijing University of Chinese Medicine, Beijing 100029, China
2. State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources (Ministry of Education of China), Collaborative Innovation Center for Guangxi Ethnic Medicine, School of Chemistry and Pharmaceutical Sciences, Guangxi Normal University, Guilin 541004, P. R. China
3. Department of Medicinal Chemistry, College of Pharmacy and Rogel Cancer Center, University of Michigan, Ann Arbor, Michigan 48109, United States