1. Istituto di Chimica Biomolecolare - CNR; via Campi Flegrei 34 80078 Pozzuoli (NA) Italy, Fax: +39 0818041770
2. Department of Chemistry and Biology; University of Salerno; via Giovanni Paolo II 132 84084 Fisciano (SA) Italy, Tel.: +39 089969392, Fax: +39 089969603