1. Graduate School of Biomedical Sciences; Nagasaki University, 1-14 Bunkyo-machi; Nagasaki 852-8521 Japan
2. Osaka University of Pharmaceutical Sciences; Osaka 569-1094 Japan
3. Division of Organic Chemistry; National Institute of Health Sciences; Tokyo 158-8501 Japan
4. Graduate School of Pharmaceutical Sciences; International University of Health and Welfare; Ohtawara 324-8501 Japan