1. Laboratory of Marine Drugs, Department of Pharmacy, Changzheng Hospital, Second Military Medical University, Shanghai 200003, P. R. China, Department of Medicinal Chemistry, School of Pharmacy, Second Military Medical University, Shanghai 200433, P. R. China, and Department of Pharmacy, Renji Hospital, Affiliated to School of Medicine, Shanghai Jiaotong University, Shanghai 200127, P. R. China