1. The Key Laboratory of Natural Medicine and Immuno-Engineering, Henan University, Kaifeng 475000, P. R. China
2. School of Pharmacy, Henan University, Kaifeng 475000, P. R. China
3. Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, Illinois 60660, USA
4. Green Catalysis Center, College of Chemistry, Zhengzhou University, Zhengzhou 450001, P. R. China
5. School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, P. R. China