1. Key Laboratory of Chemical Biology of Ministry of Education, Department of Natural Products Chemistry, School of Pharmaceutical Science, Shandong University, Jinan 250012, P.R. China
2. Natural Products Research Laboratories, UNC Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599, USA
3. School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, P.R. China
4. Department of Surgery, Duke University Medical Center, Durham, NC 27710, USA
5. Chinese Medicine Research and Development Center, China Medical University and Hospital, Taichung, Taiwan