1. School of Life Sciences, Nanjing University, Nanjing, Jiangsu Province 210023, P. R. China
2. Changzhou High-Tech Research Institute of Nanjing University and Jiangsu TargetPharma Laboratories Inc., Changzhou, Jiangsu 213164, P. R. China
3. TopoGEN, Inc., Buena Vista, Colorado 81211, United States
4. Pharmaceutical Sciences Department, College of Pharmacy at Rockford, University of Illinois at Chicago, 1601 Parkview Avenue, N310, Rockford, Illinois 61107, United States