1. Key Laboratory of Hunan Province for Study and Utilization of Ethnic Medicinal Plant Resources, Department of Chemistry & Chemical Engineering, Huaihua University, Yingfeng East Road, Huaihua, Hecheng District, Hunan 418008, P.R. China
2. Key Laboratory of Bioactive Substances and Resources Utilization of Chinese Herbal Medicine, Peking Union Medical College, Ministry of Education, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Beijing 100193, P.R. China