1. Department of Pharmacognosy, School of Pharmacy, Fudan University, 138 Yi Xue Yuan Road, Shanghai 200032, People's Republic of China, Laboratory of Phytochemistry, Kunming Institute of Botany, Academia Sinica, Kunming 650204, Yunnan, People's Republic of China, and Natural Products Laboratory, Division of Medicinal Chemistry and Natural Products, School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina 27599