1. State Key Laboratory of Natural and Biomimetic Drugs, Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing 100191, P. R. China
2. Key Laboratory of Tropical Biological Resources of Ministry of Education, School of Pharmaceutical Sciences, College of Marine Science, Hainan University, Haikou 570228, P. R. China
3. Ningbo Institute of Marine Medicine, Peking University, Ningbo 315832, P. R. China