1. State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650204, Yunnan, PRC, Graduate School of Chinese Academy of Sciences, Beijing 100039, PRC, The Key Laboratory of Chemistry for Natural Products of Guizhou Province, Chinese Academy of Sciences, Guiyang 550002, PRC, and Institute of Materia Medica, Chinese Academy of Medical Sciences, Beijing 100050, PRC