1. Department of Pharmacy, University of Patras, 26500 Rio, Patras, Greece, Institute of Organic and Pharmaceutical Chemistry, The National Hellenic Research Foundation, 48 Vas. Constantinou Avenue, 11635 Athens, Greece, Department of Biology Chemistry and Pharmacy, Freie Universität Berlin, Takustrasse 3, 14195 Berlin, Germany, and Department of Chemistry, University of Athens, Zographou, 15784 Athens, Greece