Context: To find bioactive medicinal herbs exerting anti-asthmatic activity, we investigated the effect of an aqueous extract of Urtica dioica L. (Urticaceae) leaves (UD), the closest extract to the Algerian traditional use.
Objective: In this study, we investigated the in vivo anti-asthmatic and antioxidant activities of nettle extract.
Materials and methods: Adult male Wistar rats were divided into four groups: Group I: negative control; group II: Ovalbumin sensitized/challenged rats (positive control); group III: received UD extract (1.5 g/kg/day) orally along the experimental protocol; group IV: received UD extract (1.5 g/kg/day) orally along the experimental protocol and sensitized/challenged with ovalbumin. After 25 days, blood and tissue samples were collected for haematological and histopathological analysis, respectively. The oxidative stress parameters were evaluated in the lungs, liver and erythrocytes. Then, correlations between markers of airway inflammation and markers of oxidative stress were explored.
Results: UD extract significantly (p < 0.01) inhibited eosinophilia increases in BALF (-60%) and the levels of leucocytes (-32.75%) and lymphocytes (-29.22%) in serum, and effectively suppressed inflammatory cells recruitment in the asthmatic rat model. Besides, the lipid peroxidation generated by allergen administration was significantly (p < 0.05) diminished by UD treatment in lung tissue (-48.58%). The nettle extract was also investigated for the total phenolic content (30.79 ± 0.96 mg gallic acid/g dry extract) and shows DPPH radical scavenging activity with 152.34 ± 0.37 μg/mL IC50 value.
Conclusions: The results confirmed that UD administration might be responsible for the protective effects of this extract against airway inflammation.
Keywords: Anti-asthmatic; airway inflammation; nettle; oxidative stress; polyphenols.