1. School of Pharmacy, China Pharmaceutical University, Nanjing 211198, P. R. China
2. Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing 211198, P. R. China
3. State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 211198, P. R. China
4. School of Life Science and Technology, China Pharmaceutical University, Nanjing 211198, P. R. China