1. Department
of Biotechnology, Chemistry and Pharmacy, University of Siena, I-53100 Siena, Italy
2. Centro
de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, E-28040 Madrid, Spain
3. Department
of Chemistry, “Ugo Schiff” and INSTM RU, University of Florence, 50019 Sesto Fiorentino, Florence, Italy