1. Faculty of Chemistry and Pharmacy; Sofia University, 1; J. Bourchier blvd. Sofia 1164 Bulgaria
2. Faculty of Pharmacy; Medical University of Sofia; 2 Dunav Street Sofia 1000 Bulgaria
3. Chemical Resources Laboratory; Tokyo Institute of Technology; 4259 Nagatsuta Midori-ku Yokohama 226-8503 Japan
4. NMR Laboratory; Institute of Organic Chemistry with Centre of Phytochemistry; Bulgarian Academy of Sciences; Acad. G. Bonchev Str., Bl. 9 Sofia 1113 Bulgaria