1. School of Chinese Medicine, The University of Hong Kong, 1/F, 10 Sassoon Road, Pokfulam, Hong Kong S.A.R. 00000, P.R. China.
2. School of Life Science and State Engineering Laboratory of AIDS Vaccine, Jilin University, Changchun, Jilin Province 130012, P.R. China.
3. Joint Research Center for National and Local Miao Drug, Anshun, Guizhou Province 561000, P.R. China.
4. Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P.R. China.