1. Dipartimento di Chimica e Tecnologia del Farmaco, University of Perugia, Via del Liceo 1, 06123 Perugia, Italy, Institute of Microbiology, University of Padova, Via A. Gabelli 63, 35131 Padova, Italy, and Department of Pharmaceutical Sciences, University of Padova, Via Marzolo 5, 35131 Padova, Italy