1. Okinawa Science and Technology Promotion Center, 12-75 Suzaki, Uruma, Okinawa 904-2234, Japan
2. Okinawa Prefectural Institute of Health and Environment, 2085 Aza-Ozato, Ozato, Nanjo, Okinawa 901-1202, Japan
3. Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
4. Japan Food Research Laboratories, 6-11-10 Nagayama, Tama, Tokyo 206-0025, Japan