1. Natural and Synthetic Drugs Research Center, Department of Medicinal Chemistry, Université de Liège, 1, Avenue de l'Hôpital, Tour 4(+5) Sart-Tilman, B-4000 Liège, Belgium, Department of Molecular and Structural Chemistry, Université de Namur, 61 Rue de Bruxelles, B-5000 Namur, Belgium, and Department of Human Physiology, Université de Liège, 17 Place Delcour, 4020 Liège, Belgium