1. Division of Organic Chemistry; National Institute of Health Sciences; 1-18-1, Kamiyoga, Setagaya; Tokyo; 158-8501; Japan
2. Osaka University of Pharmaceutical Sciences; Osaka; 569-1094; Japan
3. Graduate School of Biomedical Sciences; Nagasaki University; 1-14 Bunkyo-machi; Nagasaki; 852-8521; Japan