1. a Institute of Organic Chemistry, Centre of Phytochemistry, Bulgarian Academy of Sciences , Acad. G. Bonchev Str., Bl. 9, Sofia 1113, Bulgaria
2. b Agrobioinstitute, National Centre of Agricultural Science , D. Tsankov Blvd 8, Sofia 1164, Bulgaria
3. c Institute of Agriculture and Seed Science, National Centre of Agricultural Science , Prof. I. Ivanov Str. 1, Rousse 7007, Bulgaria