1. Key Laboratory of Drug-Targeting and Drug Delivery System of the Education MinistrySichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial TechnologyWest China School of PharmacySichuan University Chengdu 610041 P. R. China
2. School of Pharmaceutic ScienceChongqing University Chongqing 401331 P. R. China