1. Institute of Organic Chemistry with Centre of Phytochemistry
2. Bulgarian Academy of Sciences
3. 1113 Sofia
4. Bulgaria
5. Institute of Molecular Genetics and Genetic Engineering
6. University of Belgrade
7. 11000 Belgrade
8. Serbia
9. Department of Chemistry
10. Faculty of Medicine
11. University of Niš
12. 18108 Niš
13. University of Copenhagen
14. DK-2100 Copenhagen
15. Denmark