1. Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba-yama, Aoba-ku, Sendai 980-8578, Japan, Faculty of Pharmaceutical Sciences, Kanazawa University, Takaramachi, Kanazawa 920-0934, Japan, Tohoku College of Pharmacy, Komatsushima, Aoba-ku, Sendai 981-8558, Japan, and Daiichi Pure Chemicals Company, Ltd., Tokai, Ibaragi 319-1182, Japan