1. School of Bioresources, Hiroshima Prefectural University, 562, Nanatsuka, Shobara-shi, Hiroshima 727-0023, Japan, School of Pharmaceutical Sciences, University of Shizuoka, 52-1, Yada, Shizuoka-shi 422-8526, Japan, and Life Science Research Center, Lion Corporation, 100, Tajima, Odawara 256-0811, Japan