1. School of Molecular Sciences; Arizona State University; Tempe AZ 85287 USA
2. School of Pharmacy; Health Science Center; Xi'an Jiaotong University; Xi'an Shaanxi Province 710061 P. R. China
3. State Key Laboratory of Shaanxi for Natural Medicines Research and Engineering; Xi'an 710061 P. R. China
4. Shaanxi Institute of International Trade & Commence; Xianyang 712046 P. R. China