1. Faculty of Pharmaceutical Sciences, Hokuriku University, Ho-3 Kanagawa-machi, Kanazawa 920-1181, Japan, Molecular- Nature Limited, Plas Gogerddan, Aberystwyth, Cardiganshire SY23 3EB, U.K., Institute of Grassland and Environmental Research, Aberystwyth, Cardiganshire SY23 3EB, U.K., and Dyson Perrins Laboratory, Oxford University, Oxford OX1 3QY, U.K.