1. Laboratory of Medicinal Chemistry School of Pharmacy Kitasato University 5-9-1, Shirokane Minato-ku Tokyo 108-8641 Japan
2. Medicinal Research Laboratories School of Pharmacy Kitasato University 5-9-1, Shirokane Minato-ku Tokyo 108-8641 Japan
3. Analytical Unit for Organic Chemistry Kitasato University 5-9-1, Shirokane Minato-ku Tokyo 108-8641 Japan
4. Division of Cancer Pathophysiology National Cancer Center Research Institute 5-1-1 Tsukiji Chuo-ku Tokyo 104-0045 Japan
5. Department of Pain Control Research Jikei University School of Medicine 3-25-8, Nishi-Shimbashi Minato-ku Tokyo 105-8461 Japan
6. Supportive and Palliative Care Research Support Office National Cancer Center Hospital East 6-5-1 Kashiwanoha Kashiwa city Chiba 277-8577 Japan