ABSTRACT
Pyrrolizidine alkaloids (PAs) exist in many plants and many of them cause liver toxicity and/or cancer in humans and experimental animals. Comfrey contains as many as 14 pyrrolizidine alkaloids, including 7-acetylintermedine, 7-acetyllycopsamine, echimidine, intermedine, lasiocarpine, lycopsamine, myoscorpine, symlandine, symphytine, and symviridine. The main liver injury caused by comfrey is veno-occlusive disease, a non-thrombotic obliteration of small hepatic veins leading to cirrhosis and eventually liver failure. Patients may present with either acute or chronic clinical signs with portal hypertension, hepatomegaly, and abdominal pain as the main features. Comfrey leaves were purchased from three commercial sources and used to prepare tea in a manner consistent with the methods used by consumers. The concentration of symphytine and echimidine varied considerably between teas prepared from leaves purchased from the different vendors of plant material. Concentration of symphytine was found in the tea when steps were included to reduce N-oxides prior to analysis.
