1. Department of Medicinal Chemistry, College of Pharmaceutical Sciences of Capital Medical University, Beijing 100069, P. R. China
2. Beijing Area Major Laboratory of Peptide and Small Molecular Drugs, Engineering Research Center of Endogenous Prophylactic of Ministry of Education of China, Beijing Laboratory of Biomedical Materials, Beijing Laboratory of Oral Health, Laboratory for Clinical Medicine, Capital Medical University, Beijing 100069, P. R. China
3. School of Pharmacy, Guangxi University of Chinese Medicine, Nanning, P. R. China
4. Center for Pharmacy, University of Bergen, P. O. Box 7803, 5020 Bergen, Norway
5. Department of Chemistry, University of Bergen, P. O. Box 7803, 5020 Bergen, Norway