Analysis of herbal teas made from the leaves of comfrey (Symphytum officinale): reduction of N-oxides results in order of magnitude increases in the measurable concentration of pyrrolizidine alkaloids.
- UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
- Nicholas Oberlies, Patricia A. Sullivan Distinguished Professor of Chemistry (Creator)
- Mansukhlal Chhaganlal Wani (Contributor)
- Institution
- The University of North Carolina at Greensboro (UNCG )
- Web Site: http://library.uncg.edu/
Abstract: Objectives: To determine the relative quantities of two hepatotoxic pyrrolizidine alkaloids, symphytine and echimidine, in teas prepared from comfrey leaves (Symphytum officinale), and to determine the potential contribution of the N- oxide forms of these alkaloids to levels of the parent alkaloids.
Design: Comfrey leaves were purchased from three commercial sources and used to prepare tea in a manner consistent with the methods used by consumers. An extraction scheme was devised for extraction of the alkaloids, and a gas chromatographic method was developed to quantify the two major alkaloids, symphytine and echimidine. Recognising that the N-oxide derivatives of these alkaloids have also been identified in comfrey preparations, chemical reduction was applied to determine the total quantities of the alkaloids as free bases and as N-oxide derivatives.
Results: The concentration of symphytine and echimidine varied considerably between teas prepared from leaves purchased from the different vendors of plant material. Moreover, a much higher concentration of symphytine was found in the tea when steps were included to reduce N-oxides prior to analysis. The treatment of pure symphytine with hot water did not generate the N-oxide derivative de novo.
Conclusions: Since the pyrrolizidine alkaloids are known to be hepatotoxic, consumption of herbal teas made from comfrey leaves may be ill-advised. The concentration of pyrrolizidine alkaloids in such teas may be underestimated substantially unless the concentration of N-oxides is taken into consideration.
Analysis of herbal teas made from the leaves of comfrey (Symphytum officinale): reduction of N-oxides results in order of magnitude increases in the measurable concentration of pyrrolizidine alkaloids.
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Additional Information
- Publication
- increases in the measurable concentration of pyrrolizidine alkaloids. Public Health Nutrition 7, 919-924.
- Language: English
- Date: 2004
- Keywords
- Comfrey, Pyrrolizidine, N-oxide, Symphytum officinale, Symphytine, Echimidine