1. Department of Medicinal Chemistry, Center for Frontier Research in Medicinal Science, Kyoto Pharmaceutical University, Yamashina-Ku, Kyoto 607-8412, Japan, and Shimizu Laboratories, Marine Biotechnology Institute, 1900 Sodeshi-Cho, Shimizu, Shizuoka, 424-0037, Japan yhayashi@mb.kyoto-phu.ac.jp