Echimidine Content of Commercial Comfrey (Symphytumspp.-Boraginaceae)

Abstract

The pyrrolizidine alkaloid (PA) content of 13 commercial comfrey products sold in Canada was examined following an increased health concern about the consumption of PA-containing plant material, and particularly comfrey, the use of which had been linked to a number of cases of human poisoning during the last decade. The samples were purchased so as to be representative of the variety of sources, shapes and forms of the commercially available products. Total PA content of comfrey root samples, determined by 1H-NMR spectroscopy, has indicated significant variation both quantitatively and qualitatively. The occurrence of echimidine, probably the most toxic PA of Symphytum spp., has been evaluated by reverse-phase HPLC (RP-HPLC), TLC, and GC-MS. Echimidine was detected in 9 of the 13 samples analyzed, and was noted to be the major PA constituent of 1 root preparation-approximately 85 percent Symphytum as measured by RP-HPLC. Leaf preparations generally contained lower levels of echimidine, detected only by GC-MS, associated with lower overall quantities of extract. Of the 6 preparations identified on the package label as being derived from the species Symphytum officinale, 3 were observed to contain echimidine at varying levels, likely an indication of inaccurate species designation since substantial echimidine content is usually indicative of Symphytum officinale hybridization.