Is comfrey root more than toxic pyrrolizidine alkaloids? Salvianolic acids among antioxidant polyphenols in comfrey (Symphytum officinale L.) roots

• Published in: Food and chemical toxicology Vol. 112; pp. 178 - 187
• Main Authors: Trifan, Adriana, Opitz, Sebastian E.W., Josuran, Roland, Grubelnik, Andreas, Esslinger, Nils, Peter, Samuel, Bräm, Sarah, Meier, Nadja, Wolfram, Evelyn
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.02.2018
• Subjects: Antioxidant activity; Phenolic compounds; Pyrrolizidine alkaloids; Salvianolic acids; Symphytum officinale L; Salvianolic acids; Phenolic compounds; Symphytum officinale L; Pyrrolizidine alkaloids; Antioxidant activity
• ISSN: 0278-6915; 1873-6351
• DOI: 10.1016/j.fct.2017.12.051

Comfrey root preparations are used for the external treatment of joint distortions and myalgia, due to its analgesic and anti-inflammatory properties. Up to date, key activity-determining constituents of comfrey root extracts have not been completely elucidated. Therefore, we applied different approaches to further characterize a comfrey root extract (65% ethanol). The phenolic profile of comfrey root sample was characterized by HPLC-DAD-QTOF-MS/MS. Rosmarinic acid was identified as main phenolic constituent (7.55 mg/g extract). Moreover, trimers and tetramers of caffeic acid (isomers of salvianolic acid A, B and C) were identified and quantified for the first time in comfrey root. In addition, pyrrolizidine alkaloids were evaluated by HPLC-QQQ-MS/MS and acetylintermedine, acetyllycopsamine and their N-oxides were determined as major pyrrolizidine alkaloids in the comfrey root sample. Lastly, the antioxidant activity was determined using four assays: DPPH and ABTS radicals scavenging assays, reducing power assay and 15-lipoxygenase inhibition assay. Comfrey root extract exhibited significant antioxidant activities when compared to known antioxidants. Thus, comfrey root is an important source of phenolic compounds endowed with antioxidant activity which may contribute to the overall bioactivity of Symphytum preparations. •Phenolic compounds profile in comfrey root was characterized using HPLC-DAD-QTOF-MS/MS.•Salvianolic acids A, B and C isomers were identified for the first time in comfrey root.•Salvianolic acids may contribute to the bioactivity of comfrey root preparations.