1. Institute of Organic and Pharmaceutical Chemistry, National Hellenic Research Foundation, 48 Vass. Constantinou, Athens 116−35 Greece, Departments of Pharmaceutical Sciences and Molecular and Cell Biology and Center for Drug Discovery, University of Connecticut, 372 Fairfield Road, Storrs, Connecticut 06269, and Department of Biomedical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK