1. Key Laboratory of Medicinal Chemistry for Natural Resources, 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. State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
3. State Key Laboratory and Institute of Elemento-organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China