1. School of Pharmaceutical SciencesGuangzhou University of Chinese Medicine Guangzhou 510006 P. R. China
2. School of Pharmaceutical ScienceSun Yat-Sen University Guangzhou 510006 P. R. China
3. Guangdong Province Key Laboratory of Pharmacodynamic Constituents of Traditional Chinese Medicine and New Drugs Research, College of PharmacyJinan University Guangzhou 510632 P. R. China
4. State Key Laboratory of Marine Resource Utilization in South China Sea, College of Marine ScienceHainan University Haikou 570228 P. R. China
5. Department of Chemistry and BiochemistryUniversity of South Carolina, Columbia South Carolina 29208 USA