1. Graduate School of Pharmaceutical Sciences, Chiba University, Inage, Chiba 263‐8522 (Japan), Fax: +81 43 290 2913
2. Temko Corporation, 4‐27‐4 Honcho, Nakano, Tokyo 164‐0012 (Japan)
3. Faculty of Agriculture, Kohn Kaen University, Kohn Kaen 40002 (Thailand)
4. Institute of Molecular and Cellular Biosciences, The University of Tokyo, Yayoi, Tokyo 113‐0032 (Japan)