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