1. School of Pharmacy, Tokyo College of Pharmacy and Life Science, 1432-1, Horinouchi, Hachioji, Tokyo 192-0392, Japan1
2. Department of Medical Microbiology, University of Gothenburg, Guldhedsgatan 10, S-41346 Gothenburg, Sweden2
3. Department of Chemistry, University of Newcastle, Newcastle upon Tyne NE1 7RU, UK3