The Ethanol Extract of Syringa pubescens Turcz. Flower Ameliorates Inflammation Responses by Inhibiting the Expression of Cyclooxygenase-2/Inducible Nitric Oxide Synthase and the Release of Inflammatory Factors.

The flower of Syringa pubescens Turcz., frequently prepared as herbal tea, exhibits various biological properties, including anti-inflammatory, antioxidant, and hepatoprotective activities. Herein, we identify the chemical constituents from ethanol extract of S. pubescens flower (SPFE) and explore its antioxidant, anti-xanthine oxidase (anti-XOD), and 5-lipoxygenase (5-LOX) enzyme activities, and anti-inflammatory activities and mechanisms. SPFE contained a variety of glycosides and showed good antioxidant capacity and effectively inhibited the activity of 5-LOX and XOD enzymes in vitro. In the model of RAW264.7 cell inflammation generated by lipopolysaccharide, SPFE not only impeded the expression of inflammatory mediators and the accumulation of malondialdehyde, but also restored the capacity of antioxidant enzymes. Moreover, SPFE could notably relieve or treat inflammation by suppressing the expression of inducible nitric oxide synthase and cyclooxygenase-2 proteins. In vivo inflammation models, oral SPFE remarkably reduced the swelling of the ear, paw tissues in mice and had a good anti-inflammatory activity, reducing cell infiltration in the claw tissue, and restoring the degree of oxidative damage in the organism. Our findings demonstrate that SPFE exhibits promising potential as a novel therapeutic agent or nutraceutical for anti-inflammatory applications.