1. Department of Natural Product Chemistry, School of Pharmacy, Second Military Medical University, 325 Guohe Road, Shanghai 200433, P. R. China
2. Key Laboratory of Marine Bio-resources Sustainable Utilization, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, P. R. China
3. Department of Ethnobotany, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650204, P. R. China