1. Department of Medicinal Natural ProductsWest China School of PharmacySichuan University Chengdu 610041 P. R. China
2. State Key Laboratory of Phytochemistry and Plant Resources in West ChinaYunnan Key Laboratory of Natural Medicinal ChemistryKunming Institute of BotanyChinese Academy of Sciences 132 Lanhei Road Kunming China
3. University of Chinese Academy of Sciences Beijing 100049 China