1. Faculty of Pharmacy, Meijo University, Tempaku, Nagoya 468-8503, Japan, Tokai Gakuen University, Miyoshi, Aichi 470-0207, Japan, Department of Chemistry, University of Papua New Guinea, Papua New Guinea, and Department of Biochemistry, Kyoto Prefectural University of Medicine, Kamigyou-ku, Kyoto 602-0841, Japan