14E-31 |
Preparation of pyrrolizidine alkaloid standards from Comfrey |
K. K. COOK, M. Y. Jenkins, P. Delmonte, K. D. White, M. P. Yurawecz, and J. I. Rader. Center for Food Safety & Applied Nutrition, U.S. Food & Drug Administration, Office of Nutritional Products, Labeling & Dietary Supplements, 5100 Paint Branch Pkwy., HFS-840, College Park, MD 20740-3835 (Symphytum officionale (common comfrey), ( prickley comfrey), and S. x uplandicum ( Russian comfrey) are a source of pyrrolizidine alkaloids (PAs) that may present a health hazard to consumers when ingested. There are no commercially available standards for PAs that are contained in comfrey and there is a need for such authentic standards. The objectives of the study are to extract, purify and identify PAs found in comfry leaves and roots. An authentic sample of Symphytum officianale roots and leaves was purchased from Botanical Liaisons, Boulder, CO., USA. and a voucher specimen was placed on file at FDA. The commercially available PA retrosine and its N-oxide (neither of which are found in comfrey) were purchased as reference standards for PAs. Since the roots are reported to contain the most concentrated amounts of PAs, the roots were ground to a powder, weighed into an erlenmeyer flask and 75 mL of methanol added. The mixture was shaken at 200 rpm at 60°C for 16 hours, filtered, and the methanolic filtrate distilled. The residue was acidified. Zn dust was added and the slurry stirred for 2 h to reduce the remaining N-oxides to bases. The solution was made basic by adding 1.25 mL of ammonium hydroxide for each 5 mL filtered. The resultant basic solution was poured into a ChemElut column and after 5 minutes equilibration, the pyrrolizidine bases were eluted with chloroform: ammonium hydroxide 99:1 v/v. The eluate was evaporated and taken up in 1 mL of methanol. Lycopsamine, 7-acetyl-lycopsamine, symphytine and echimedine with stereoisomers were identified by corresponding molecular weights through mass spectrometry. This mixture was confirmed to contain PAs by thin layer chromatography. These compounds are being separated by a phenyl column and further identifications will produce authentic pyrrolizidine alkaloid standards from comfrey.
Session 14E, Nutraceuticals & Functional Foods: General I
|