1. Laboratory for Natural Product Chemistry
2. College of Pharmacy
3. South Central University for Nationalities
4. Wuhan 430074, P. R. China
5. State Key Laboratory of Oncology in South China
6. Cancer Center, Sun Yat-sen University
7. Guangzhou 510060, P. R. China
8. College of Chemistry and Material Sciences
9. College of Chemistry
10. Central China Normal University
11. Wuhan 430079, P. R. China