1. State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650204, Yunnan, P. R. China, Yunnan Pharmacological Laboratory of Natural Products, Kunming Medical College, Kunming 650031, Yunnan, P. R. China, and Institute of Materia Medica, Chinese Academy of Medical Sciences, Beijing 100050, Beijing, P. R. China