1. Dipartimento Farmaco−Chimico, University of Messina, Viale Annunziata, 98168 Messina, Italy, Department of Medicinal Chemistry, IRBM, MRL Rome, Via Pontina Km30.600, 00040 Pomezia, Roma, Italy, Research Center for Infectious Diseases, University of Würzburg, Röntgenring 11, D-97070 Würzburg, Germany, and Institute of Pharmacy and Food Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany