1. State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650204, People's Republic of China, Kunming Medical College, Yunnan Province Key Laboratory of the Natural Medicine Pharmacology, Kunming 650000, People's Republic of China, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, People's Republic of China, and Guiyang Medical College, Guiyang 550004, People's Republic of China