1. Division of Chemistry, Graduate School of Science and §Division of Innovative Research, Creative Research Institution, Hokkaido University, North 21, West 10, Kita-ku, Sapporo 001-0021, Japan
2. Research Center for Tropical Diseases, Kitasato Institute for Life Sciences and ¶Graduate School of Infection Control Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan