Symphytum: Comfrey is comfrey is comfrey: or is it?
by Paul Bergner
Medical Herbalism 04-30-94 6(1): 13
The pyrrolizidine content of thirteen commercial Comfrey products sold in Canada was examined due to concern about its safety. The samples were representative of the variety of sources, shapes, and forms of commercially available products. Echimidine which is probably the most toxic PA of Symphytum spp. was detected in nine of the thirteen samples. Chemotaxonomic studies have indicated echimidine is often not found in Symphytum officinale and when it is, the PA is in low levels. High levels of echimidine are regarded as a strong indicator of non-Symphytum offinale origin. It is a significant component of Symphytum asperum, and S.asperum’ s hybridization with S. officinale such as S.uplandicum (Russian comfrey). The level of Echimidine was highest in the root samples while leaf samples were so low as to be detectable only by the highly sensitive GC-MS method. The level of echimidine varied widely, from very little to the most abundant component of the extracted PA’s in two of the products. Six of the samples were labeled as S. officinale. Only 3 were found to be free of echimidine. The high incidence of echimidine in these commercial comfrey products raised doubts about the authenticity of herbal products labeled S. officinale actually being Symphytum uplandicum, or a hybrid species.
Proper identification of Symphytum species, is very important if you are planning to use it. Unfortunately commercial preparations are often labeled incorrectly and, to make matters worse, research on comfrey has been confusing due to errors or lack of clarity in species identification. See the related article “Symphytum: Hepatotoxicity of pyrrolizidine alkaloids.”Awang D, Dawson B., et al. “Echimidine content of commercial comfrey (Symphytum spp.-Boraginaceae). Journal of Herbs, Spices & Medicinal Plants, Vol. 2(1):2-33,1993