In Vitro and In Vivo Anti-inflammatory Effects of Struthanthus vulgaris

Struthanthus vulgaris is probably the most common medicinal mistletoe plant in Brazil, and has been used in folk medicine as an anti-inflammatory agent and for cleaning skin wounds. Our proposal was to evaluate the anti-inflammatory activity of S. vulgaris ethanol leaf extract and provide further insights of how this biological action could be explained using in vitro and in vivo assays. In vitro anti-inflammatory activity was preliminarily investigated in lipopolysaccharide/interferon gamma-stimulated macrophages based on their ability to inhibit nitric oxide production and tumor necrosis factor-alpha. In vivo anti-inflammatory activity of S. vulgaris ethanol leaf extract was investigated in the mice carrageenan-induced inflammation air pouch model. The air pouches were inoculated with carrageenan and then treated with 50 and 100 mg/kg of S. vulgaris ethanol leaf extract or 1 mg/kg of dexamethasone. Effects on the immune cell infiltrates, pro- and anti-inflammatory mediators such as tumor necrosis factor-alpha, interleukin 1, interleukin 10, and nitric oxide, were evaluated. The chemical composition of S. vulgaris ethanol leaf extract was characterized by LC-MS/MS. In vitro S. vulgaris ethanol leaf extract significantly decreased the production of nitric oxide and tumor necrosis factor-alpha in macrophages and did not reveal any cytotoxicity. In vivo, S. vulgaris ethanol leaf extract significantly suppressed the influx of leukocytes, mainly neutrophils, protein exudation, nitric oxide, tumor necrosis factor-alpha, and interleukin 1 concentrations in the carrageenan-induced inflammation air pouch. In conclusion, S. vulgaris ethanol leaf extract exhibited prominent anti-inflammatory effects, thereby endorsing its usefulness as a medicinal therapy against inflammatory diseases, and suggesting that S. vulgaris ethanol leaf extract may be a source for the discovery of novel anti-inflammatory agents.