1. Pharmaceutical and Medicinal Chemistry Institute of Pharmacy and Food Chemistry Julius Maximilian University of Würzburg 97074 Würzburg Germany
2. Current address: Department of Chemistry and Molecular Biology University of Gothenburg SE-412 96 Göteborg Sweden
3. Division of Pharmaceutical Chemistry Department of Pharmacy National and Kapodistrian University of Athens Panepistimiopolis-Zografou 15771 Athens Greece