1. Faculty of Pharmacy, University of Ljubljana, Aškerčeva 7, 1000 Ljubljana, Slovenia, Research and Development Division, Lek d.d., Celovška 135, 1000 Ljubljana, Slovenia, Faculty of Medicine, Institute of Microbiology and Immunology, Korytkova 2, 1105 Ljubljana, Slovenia, and Institute of Organic Chemistry, Technical University of Graz, Stremayrgasse 16, A-8010 Graz, Austria