1. Natural Products Research Center, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, Sichuan 610041, P. R. China
2. Department of Biomedical Engineering, Southern University of Science and Technology, No. 1088, Xueyuan Rd., Xili, Nanshan District, Shenzhen, Guangdong 518055, P. R. China
3. University of Chinese Academy of Sciences, 19 A Yuquan Road, Shijingshan District, Beijing 100049, P. R. China