[1. Fliebich BL, Grozdeva M, Hess S, et al. Petasites hybridus extracts in vitro inhibit COX-2 and PGE2 release by direct interaction with the enzyme and by preventing p42/44 MAP kinase activation in rat primary microglial cells. Planta Med. 2005;71:12-19.10.1055/s-2005-837744]Search in Google Scholar
[2. ***PDR for Herbal Medicines, Third Edition, Thompson PDR, Montvale, 2004, 220-221]Search in Google Scholar
[3. Mogoșanu GD, Pintea A, Bejenaru LE, et al. HPLC analysis of carotenoids from Senecio vernalis and S. jacobaea (Asteraceae). Farmacia. 2009;57(6): 780-786.]Search in Google Scholar
[4. ***Committee on Herbal Medicinal Products (HMPC). Assessment report on Symphytum offi cinale L., radix (EMA/HMPC/572844/2009), 2011]Search in Google Scholar
[5. ***Scientifi c Opinion on Pyrrolizidine alkaloids in food and feed. EFSA Journal. 2011;9:2406-2540.]Search in Google Scholar
[6. Roeder E. Medicinal plants in Europe containing pyrrolizidine alkaloids. Pharmazie. 1995;50:83-98.]Search in Google Scholar
[7. Mattocks AR. Spectrophotometric determination of unsaturated pyrrolizidine alkaloids. Anal. Chem. 1967;39:443-447.10.1021/ac60248a006]Search in Google Scholar
[8. Mattocks AR. Spectrophotometric determination of pyrrolizidine alkaloidssome improvements. Anal. Chem. 1968;40:1749-1750.10.1021/ac60267a024]Search in Google Scholar
[9. Barko Bartkowski JP, Wiedenfeld H, Roeder E. Quantitative Photometric Determination of Senkirkine in Farfarae Folium. Phytochem. Anal. 1997;8: 1-8.]Search in Google Scholar
[10. Birecka H, Catalfamo JL, Eisen RN. A sensitive method for detection and quantitative determination of pyrrolizidine alkaloids. Phytochemistry. 1981;20:343-344.10.1016/0031-9422(81)85124-2]Search in Google Scholar
[11. Ancuceanu R, Istudor V, Dinu M, Codreanu M. Contribution to the study of some Cuscuta species. Note 2. Use of the Constantinescu bioassay in the study of the correlations between Cuscuta sp. and their hosts. Farmacia. 2005;53:63-75.]Search in Google Scholar
[12. Couet CE, Crews C, Hanley AB. Analysis, separation, and bioassay of pyrrolizidine alkaloids from comfrey (Symphytum offi cinale). Nat Toxins. 1996;4:163-167.10.1002/19960404NT3]Search in Google Scholar
[13. Wildi E, Langer T, Schaffner W, Buter KB. Quantitative analysis of petasin and pyrrolizidine alkaloids in leaves and rhizomes of in situ grown Petasites hybridus plants. Planta Med. 1998;64:264-26710.1055/s-2006-95742217253240]Search in Google Scholar