1. Department of Natural Medicinal Chemistry; China Pharmaceutical University; Nanjing 211198 P. R. China
2. Key Laboratory of Drug Quality Control and Pharmacovigilance (China Pharmaceutical University), Ministry of Education; China Pharmaceutical University; 24 Tongjiaxiang Nanjing 210009 P. R. China
3. Key Laboratory of Biomedical Functional Materials; China Pharmaceutical University; Nanjing 211198 P. R. China
4. Research Institute for Science and Technology; Tokyo University of Science; Chiba 278-8510 Japan