1. Department of Biomedical Sciences, University of Sassari, Sassari, Italy;
2. CNR, Institute of Biomolecular Chemistry, Li Punti, Sassari, Italy;
3. Department of Chemistry and Pharmacy, University of Sassari, Sassari, Italy;
4. Department Medical, Surgical and Experimental Sciences, University of Sassari, Sassari, Italy;
5. Sacro Cuore Catholic University, Institute of Microbiology, Rome, Italy.