1. Division of Advanced Chemical Biology, Graduate School of Advanced Life Science, Frontier Research Center for the Post-Genome Science and Technology, Hokkaido University, N21, W11, Sapporo 001-0021, Japan, YAMASA Company Choshi, Chiba 288-0056, Japan, Drug-Seeds Discovery Research Laboratory, National Institute of Advanced Industrial Science and Technology (AIST), Sapporo 062-8517, Japan, and Shionogi & Company, Ltd., Osaka 541-0045, Japan