1. Institute of Medicinal Plant Development, Chinese Academy of Medical Science, Peking Union Medical College, Beijing 100094, People's Republic of China, Department of Biology and Chemistry, City University of Hong Kong, Hong Kong, People's Republic of China, Shenzhen Research Institute of Hongkong City University, Shenzhen 518057, People's Republic of China, and Department of Chemistry, College of Chemistry & Environmental Science, Hebei University, Baoding 071002, People's Republic of China