1. Department of Organic Chemistry, University of Chemical Technology and Metallurgy, Sofia 1756, Bulgaria
2. Department of Analytical Chemistry, University of Chemical Technology and Metallurgy, Sofia 1756, Bulgaria
3. Institute of Neurobiology, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
4. Institute of Organic Chemistry with centre of phytochemistry, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
5. Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria