1. Biological Chemistry Section, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, South Kensington, London SW7 2AZ, United Kingdom, UMR 1089 - Xénobiotiques, INRA, BP 3, 31931 Toulouse Cedex 9, France, Laboratoire de Pharmacognosie, Université Montpellier I, 15 Avenue Charles Flahault, B.P. 14491, 34093 Montpellier Cedex 5, France, LABERCA, Ecole Nationale Vétérinaire, BP 50707, 44307 Nantes Cedex 3, France