[1] Sofia Univ St Kliment Ohridski, Fac Chem & Pharm, Dept Pharmaceut & Appl Organ Chem, 1 James Bourchier Blvd, Sofia 1164, Bulgaria
[2] Trakia Univ, Med Fac, Dept Gen & Clin Pathol, 11 Armeiska Str, Stara Zagora 6000, Bulgaria
[3] Univ Forestry, Fac Ecol & Landscape Architecture, Dept Plant Pathol & Chem, 10 Kliment Ohridsky Blvd, Sofia 1756, Bulgaria
[4] Med Univ Sofia, Fac Pharm, Dept Pharmacol Pharmacotherapy & Toxicol, 2 Dunav Str, Sofia 1000, Bulgaria