1. Department of Medicinal Chemistry School of Pharmacy China Pharmaceutical University 639 Longmian Avenue Nanjing Jiangsu 211198 China
2. State Key Laboratory of Bioorganic and Natural Products Chemistry Shanghai Institute of Organic Chemistry Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
3. Instrumental Analysis Center China Pharmaceutical University 24 Tong Jia Xiang Nanjing Jiangsu 210009 China