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, HsiehS Biotech. Co., Ltd., Va. 11a, No.15 Road, Tan Thuan Export Processing Zone, District 7, Ho Chi Minh City, Vietnam, and Graduate School of Chinese Academy of Sciences, Beijing 100039, P. R. China