1. Faculty of Mathematics and Natural Sciences, South-West University, Neofit Rilski 66, Ivan Mihailov Str. 2700, Blagoevgrad, Bulgaria
2. Laboratory of Free Radical Processes, Institute of Neurobiology, Bulgarian Academy of Sciences, Acad. G. Bonchev Bl. 23, Sofia 1113, Bulgaria
3. Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna Pot 113, Ljubljana 1000, Slovenia
4. Charles University, Faculty of Science, Section of Chemistry, Hlavova 2030/8 12843, Prague 2, Czech Republic
5. Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str. Bl. 9, Sofia 1113, Bulgaria