1. State Key Laboratory
of Grassland Agro-Ecosystems, College of Pastoral Agriculture Science
and Technology, Lanzhou University, Lanzhou, Gansu 730000, People’s Republic of China
2. Gansu University of Chinese Medicine, Lanzhou, Gansu 730000, People’s Republic of China
3. Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, United States