1. Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education; Yunnan Provincial Center for Research & Development of Natural Products; School of Chemical Science and Technology, Yunnan University, Kunming 650091, P. R. China
2. School of Chemistry and Chemical Engineering; Key Laboratory of Theoretical Organic Chemistry and Functional Molecular, Ministry of Education, Hunan University of Science and Technology, Xiangtan 411201, P. R. China
3. School of Life and Pharmaceutical Sciences, Dalian University of Technology, Dalian 116081, P. R. China
4. Department of Medicinal Chemistry, School of Pharmacy, Xi’an Jiaotong University, Xi’an 710061, China