1. School of Pharmacy Tokyo University of Pharmacy and Life Sciences 1432-1 Horinouchi Hachioji Tokyo 192-0392 Japan
2. Department of Chemistry, Biochemistry and Pharmaceutical Sciences University of Bern Freiestrasse 3 CH-3012 Bern Switzerland
3. Faculty of Chemistry and Pharmacy University of Regensburg Universitätsstr. 31 D-93053 Regensburg Germany