1. Division of Molecular and Cellular Immunoscience, Department of Biomolecular Sciences, Faculty of Medicine; Saga University, 5-1-1 Nabeshima; Saga 849-8501 Japan
2. Department of Natural Products Chemistry, Graduate School of Pharmaceutical Sciences; Kyushu University, 3-1-1 Maidashi Higashi-ku; Fukuoka 812-8582 Japan