1. Department of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, D-37077 Göttingen, Germany, Institute of Oceanology, Chinese Academy of Sciences, Nanhai Road 7, 266071 Qingdao, People's Republic of China, Graduate School of the Chinese Academy of Sciences, Yuquan Road 19A, 100039 Beijing, People's Republic of China, and Oncotest GmbH, Am Flughafen 12-14, D-79108 Freiburg, Germany