1. Department of Applied Biochemistry, Faculty of Agriculture, Shizuoka University, 836 Ohya, Shizuoka 422-8529, Japan; Department of Chemistry, Faculty of Science, Shizuoka University, 836 Ohya, Shizuoka 422-8529, Japan; and Research Institute, Kagome Company, Ltd., 17 Nishitomiyama, Nishinasuno-machi, Nasu-gun, Tochigi 329-2762, Japan