1. State Key Laboratory of Natural and Biomimetic Drugs; Institute of Ocean Research; Peking University; Beijing 100191 P. R. China
2. Department Marine Zoology; Naturalis Biodiversity Center; Darwinweg 2 2333 CR Leiden The Netherlands
3. Institute für Pharmazeutische Biologie und Biotechnologie; Heinrich-Heine - Universität Düsseldorf; 40225 Düsseldorf Germany