1. Department of Pharmacognosy and Phytochemistry, Meiji Pharmaceutical University, Noshio 2-522-1, Kiyose-shi, Tokyo 204-8588, Japan, Kotaro Pharmaceutical Co., Ltd., Nakatsu 2-5-23, Kitaku, Osaka 531-0071, Japan, and Faculty of Pharmaceutical Sciences, Chiba University, Yayoi-Cho 1-33, Inage-ku, Chiba 263-0022, Japan