1. Department of Biology, Premedical Sciences, Dokkyo Medical University, 880 Kitakobayashi, Mibu-machi, Shimotsuga-gun, Tochigi 321-0293, Japan
2. Department of Chemistry and Life Science, School of Advanced Engineering, Kogakuin University, 2665–1 Nakano, Hachioji 192-0015, Japan
3. Department of Chemistry, Keio University, 3–14–1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223–8522, Japan
4. National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Nishi-2–13, Inada-cho, Obihiro, Hokkaido 080–8555, Japan