1. Department of Medicinal Chemistry, Center for Frontier Research in Medicinal Science and Physical Chemistry, 21st Century COE Program, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8412, Japan, PRESTO, JST, Kawaguchi, Saitama 332-0012, Japan, and Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan