1. Department of Organic Synthesis, University of Chemical Technology and Metallurgy, 8 Kliment Ohridski Blvd., 1756 Sofia, Bulgaria
2. Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str. Bl. 9, 1113 Sofia, Bulgaria
3. Department of Infectious Diseases, Parasitology and Tropical Medicine, Medical University, 15A Vasil Aprilov Blvd., 4002 Plovdiv, Bulgaria
4. Faculty of Pharmacy, Medical University of Sofia, 2 Dunav Str., 1000 Sofia, Bulgaria
5. Institute of Physical Chemistry, Bulgarian Academy of Sciences, Build. 11, 1113 Sofia, Bulgaria