1. College of Pharmacy, Shaanxi University of Chinese Medicine , Xi’an 712046 , Shaanxi , P. R. China
2. Shaanxi Key Laboratory of Basic and New Herbal Medicament Research , Xi’an 712046 , P. R. China
3. Shaanxi Institute of Food and Drug Administration and Inspection , Xi’an 712046 , Shaanxi , P. R. China