1. Department of Food and Medicine, Guizhou Vocational College of Agriculture, Qingzhen 551400, P. R. China
2. State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang 550014, P. R. China
3. The Key Laboratory of Chemistry for Natural Products of Guizhou Province and Chinese Academy of Sciences, Guiyang 550014, P. R. China