1. Chongqing Key Laboratory of Natural Product Synthesis and Drug Research Innovative Drug Research Center School of Pharmaceutical Sciences Chongqing University Chongqing 401331 P. R. China
2. Chemical Biology Research Center School of Pharmaceutical Sciences Chongqing University Chongqing 401331 P. R. China
3. Key Laboratory of Biorheological Science and Technology Ministry of Education College of Bioengineering Chongqing University 400044 Chongqing P. R. China