1. a Dept. of Pharmacognosy , School of Pharmaceutical Sciences, Beijing Medical University , Beijing, 100083, China
2. b NMR Laboratory , Academy of Military Medical Sciences , Beijing, 100850, China
3. c Analysis and Computation Center, Beijing Medical University , Beijing, 100083, China
4. d Institute for Pharmaceutical Biology, University of Munich , Karlstrasse 29, D-80333, Munich, FRG