1. Department of Pharmaceutical and Toxicological Chemistry, University of Naples “Federico II”, I-80131 Naples, Italy; Department of Pharmaceutical Sciences, University of Salerno, I-84084 Fisciano, Italy; Department of Organic Chemistry “Ugo Schiff”, Department of Neurological Sciences, Department of Pharmaceutical Sciences, and Laboratory of Peptide and Protein Chemistry and Biology, University of Florence, I-50019 Sesto Fiorentino, Italy