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Urtica urens dry extract as contained in Combudoron® prevented inflammatory edema in vivo
Combudoron®, an herbal remedy containing ethanolic extracts from Urtica urens (Urtica) and Arnica montana (Arnica), is authorized (according to the anthroposophical under-standing of humankind and nature) for the treatment of insect bites, sunburns, general first and second-degree burns, and radiation injuries, respectively. All of these pathologies share initial inflammatory reactions eventually leading to typical symptoms such as redness, pain and edema formation. Leukotrienes produced by 5-lipoxygenase (5-LOX) as part of the arachidonic acid (AA) pathway are key mediators for the onset and promotion of inflammation and preparations from Arnica and Urtica are well known for their anti-inflammatory properties. Both extracts were analyzed for inhibition of recombinant human 5-LOX and the anti-edema efficacy of both extracts were determined in vivo using the AA-induced ear edema model in mice. The right ears of ICR mice were topically treated with 0.6-12 mg Urtica or 0.6 and 6 mg Arnica dry extract before and after challenge with 2 mg AA. Ear swelling was measured 60 min after AA challenge. Urtica and Arnica concentration-dependently inhibited 5-LOX activity in vitro (IC50: 59 and 3.5 µg/ml, respectively). However, in vivo Urtica but not Arnica revealed a dose-dependent and significant anti-edema activity starting at a dose of 1 mg/ear. These experimental data suggest that Combudoron® may be effective in the prevention of edema formation and thus may ease inflammatory symptoms in the treatment of e. g., mild burns and insect bites. However, inhibition of 5-LOX might not be solely accountable for this effect and further studies are required to define the mechanisms of action of both extracts.
Article published online:
13 December 2021
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