Background and purpose: Previously, we reported the anti-inflammatory properties of Nasturtium officinale (watercress) in several models of acute inflammation. This study was designed to explore the effects of topical and systemic administrations of N. officinale in the two chronic inflammatory models and to evaluate the role of TNF-α and IL-1β in these effects.
Experimental approach: Folin-Ciocalteu and aluminum chloride methods were used to estimate the extract's total phenol and flavonoid content, respectively. Carrageenan-induced paw edema was carried out and TNF-α and IL-1β concentrations in the carrageenan-treated paw tissue were determined. Formalin injection into rat hind paws (7 days) and the application of 12-O-tetradecanoyl phorbol-13-acetate (TPA) on mouse ears (9 days) were used to simulate chronic inflammation. Furthermore, a histological assessment of the inflamed tissues was carried out.
Findings/results: The extract's flavonoid and phenolic contents were 90.26 ± 4.81 mg rutin equivalents/g and 68 ± 8.16 gallic acid equivalents/g gallic acid, respectively. N. officinale pretreatment in all doses administered considerably decreased carrageenan-induced edema. The extract also reduced IL-1β levels in carrageenan- treated paws while did not affect TNF-α levels. Oral and topical administrations of N. officinale considerably reserved the paw and ear edema. The extract also ameliorated the tissue injuries due to formalin and TPA challenges.
Conclusion and implications: The data confirmed the topical and systemic anti-inflammatory effects of watercress against two chronic models of inflammation. They suggested that these properties are not related to TNF-α but could be attributed to inhibition of IL-1β and inhibition of leukocyte infiltration.
Keywords: Anti-inflammatory; Interleukin-1 beta; Nasturtium officinale; Tetradecanoyl phorbol acetate; Tumor necrosis factor-alpha.
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