1. College of Life Science, Northwest Normal University, Lanzhou 730070, P. R. China
2. Gansu Provincial Academic Institute for Medical Research, Lanzhou 730050, P. R. China
3. Bioactive Products Engineering Research Center for Gansu Distinctive Plants, Northwest Normal University, Lanzhou 730070, P. R. China
4. Institute of New Rural Development, Northwest Normal University, Lanzhou 730070, P. R. China