1. Department of Natural Medicinal Chemistry; China Pharmaceutical University; Nanjing 210009 P. R. China
2. Key Laboratory of Biomedical Functional Materials; China Pharmaceutical University; Nanjing 211198 P. R. China
3. School of Continuing Education; China Pharmaceutical University; Nanjing 211198 P. R. China
4. Key Laboratory of Drug Quality Control and Pharmacovigilance; Ministry of Education; China Pharmaceutical University; Nanjing 210009 P. R. China
5. Jiangsu Food & Pharmaceutical Science College; Huaian 223003 P. R. China