1. State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650204, P.R. China, Graduated School of Chinese Academy of Sciences, Beijing 100039, P.R. China, College of Pharmaceutical Sciences, Dali University, Dali 677100, P.R. China, and The Key Laboratory of Chemistry for Natural Product of Guizhou Province and Chinese Academy of Science, Guiyang 550002, P.R. China