1. Chongqing Key Laboratory of Natural Product Synthesis and Drug Research, 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. Beijing National Laboratory for Molecular Sciences, Beijing 100190, P. R. China