1. Department of Chemistry, National and Kapodistrian University of Athens, 15771 Athens, Greece
2. Institute of Chemical Biology, National Hellenic Research Foundation, 11635 Athens, Greece
3. Department of Biology, National and Kapodistrian University of Athens, 15771 Athens, Greece
4. Istituto ISOF, Area della Ricerca di Bologna CNR, Via P. Gobetti 101, 40129 Bologna, Italy