1. Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., bl. 9, Sofia 1113, Bulgaria. Fax: (+359)(2)8700225
2. The Stephan Angeloff Institute of Microbiology, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., bl. 26, Sofia 1113, Bulgaria
3. Institute of Chemistry and Chemical Technology, Mongolian Academy of Sciences, Ulaanbataar 51, Mongolia