1. School of Pharmaceutical Sciences, Kyushu University of Health and Welfare, 1714-1 Yoshino-cho, Nobeoka 882-8508, Japan, Faculty of Pharmaceutical of Sciences, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan, and Breeding and Physiology Laboratory, Tsukuba Medicinal Plant Research Station, National Institute of Health Sciences, 1 Hachimandai, Tsukuba 305-0843, Japan