1. School of Chinese Medicine, Hong Kong Baptist University, 7 Baptist University Road, Kowloon, Hong Kong 999077, P. R. China
2. YMU-HKBU Joint Laboratory of Traditional Natural Medicine, Yunnan Minzu University, Kunming 650500, P. R. China
3. Key Laboratory for Tibet Plateau Phytochemistry of Qinghai Province, College of Pharmacy, Qinghai Nationalities University, Xining 810007, P. R. China