1. School of Pharmacy, Guizhou Provincial Engineering Technology Research Center for Chemical Drug R&D, Guizhou Medical University, 561113 Guiyang, P. R. China
2. State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medcial University, 550014 Guiyang, P. R. China
3. Department of Chemistry, Institute of Synthesis and Application of Medical Materials, Wannan Medical College, 241002 Wuhu, P. R. China