1. The Graduate School of Food and Medicinal Sciences and Faculty of Pharmaceutical Sciences, Kobe Gakuin University, Nishi-ku, Kobe 651-2180, Japan, Department of Biochemistry, Tohoku Pharmaceutical University, Aoba-ku, Sendai 981-8558, Japan, and Medicinal Chemistry Group, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709