1. Department of Life Science, Faculty of Science, Okayama University of Science, 1-1 Ridai-cho, Kita-ku, Okayama 700-0005, Japan
2. Department of Biomedical chemistry, Faculty of Medicine, Oita University, 1-1 Hasama-machi, Oita 879-5593, Japan
3. Ensuiko Sugar Refining Co. Ltd, Tokyo, Japan