Apigenin-7-Glucuronide from Urera aurantiaca Inhibits Tumor Necrosis Factor Alpha and Total Nitrite Release in Lipopolysaccharide-Activated Macrophages

Abstract

Urera aurantiaca is an Argentinean medicinal and edible species traditionally used to treat symptoms of inflammation. The aim of this study was to evaluate the anti-inflammatory activity of a methanol extract and its major compound. U. aurantiaca aerial parts were extracted with methanol by maceration. A phytochemical analysis was performed, and the extract's major component, apigenin-7-glucuronide (A7G), was identified by spectroscopic and HPLC methods. The analysis of the inflammatory mediators nitric oxide (NO) and tumor necrosis factor alpha (TNF-α) in lipopolysaccharide- (LPS-) stimulated macrophages were used in the evaluation of the extract and the major compound anti-inflammatory effects. The extract reduced LPS-augmented NO release from 100 μg/mL (27%), reaching the highest inhibition at 1000 μg/mL (96.3%), while A7G reduced it 30.7% at 1 μg/mL, and its maximum effect was 97.1% at 10 μg/mL. In the TNF-α model, the extract at 500 and 1000 μg/mL reduced LPS-augmented TNF-α by 13.5% and 93.9%, respectively; meanwhile, A7G reduced it by 26.2% and 83.8% at 5 and 10 μg/mL, respectively. U. aurantiaca popular use was validated. In the present study, for the first time, A7G was isolated from U. aurantiaca; furthermore, A7G showed anti-inflammatory effect in the macrophage cell line RAW264.7 (ATCC) and seems to be responsible for the extract anti-inflammatory effect.