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Phytother Res. 2015 Aug;29(8):1117-22. doi: 10.1002/ptr.5356. Epub 2015 Apr 16.

Comparative Study of the Biological Activity of Allantoin and Aqueous Extract of the Comfrey Root.

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University of Niš, Department for Pharmacy, Faculty of Medicine, Blvd. Dr Zoran Djindjić 81, 18000 Niš, Serbia.
University of Niš, Faculty of Technology, Bulevar oslobodjenja 124, Leskovac, Serbia.
University of Niš, Department for Cell and Tissue Engineering, Institute of Biology and Human Genetics, Faculty of Medicine, Blvd. Dr Zoran Djindjić 81, 18000 Niš, Serbia.


This study investigates the biological activity of pure allantoin (PA) and aqueous extract of the comfrey (Symphytum officinale L.) root (AECR) standardized to the allantoin content. Cell viability and proliferation of epithelial (MDCK) and fibroblastic (L929) cell line were studied by using MTT test. Anti-irritant potential was determined by measuring electrical capacitance, erythema index (EI) and transepidermal water loss of artificially irritated skin of young healthy volunteers, 3 and 7 days after application of creams and gels with PA or AECR. Pure allantoin showed mild inhibitory effect on proliferation of both cell lines at concentrations 40 and 100 µg/ml, but more pronounced on MDCK cells. Aqueous extract of the comfrey root effect on cell proliferation in concentrations higher than 40 µg/ml was significantly stimulatory for L929 but inhibitory for MDCK cells. Pharmaceutical preparations that contained AECR showed better anti-irritant potential compared with PA. Creams showed better effect on hydration and EI compared with the gels that contained the same components. Our results indicate that the biological activity of the comfrey root extract cannot be attributed only to allantoin but is also likely the result of the interaction of different compounds present in AECR. Topical preparations that contain comfrey extract may have a great application in the treatment of skin irritation.


allantoin; anti-irritant potential; comfrey; extract; proliferation; viability

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