[1] Bulgarian Acad Sci, Inst Organ Chem, Ctr Phytochem, Sofia 1113, Bulgaria
[2] Univ Chem Technol & Met, Dept Organ Chem, Sofia 1756, Bulgaria
[3] Med Univ Sofia, Fac Pharm, Dept Pharmacol Pharmacotherapy & Toxicol, Lab Drug Metab & Drug Toxicity, Sofia 1000, Bulgaria
[4] Med Univ Sofia, Fac Med, Dept Med Phys & Biophys, Sofia 1431, Bulgaria
[5] Bulgarian Acad Sci, Inst Biodivers & Ecosyst Res, Sofia 1113, Bulgaria