Li-Chen Ge1, Hong-Sheng Wang2. 1. Department of Microbial and Biochemical Pharmacy, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China. 2. Department of Microbial and Biochemical Pharmacy, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China. Electronic address: whongsh@mail.sysu.edu.cn.