In Vitro Anti-Inflammatory Activity of Ilex cornuta Extract Mediated by Inhibition of Extracellular Signal-Regulated Kinase Phosphorylation

Abstract

Ilex cornuta, commonly known as Chinese holly, is an evergreen shrub from the family Aquifoliaceae, and it is widely distributed in Korea and China. In folk medicine, the leaves of I. cornuta are used for treatment of several disorders, including weakness of the waist and knees, arthrodynia, headache, acute conjunctivitis, toothache, urticaria, rheumatic arthralgia, and cardiovascular diseases. In this study, we investigated the anti-inflammatory effects of an I. cornuta leaf ethanol extract (ILE) and its underlying mechanisms of action. The anti-inflammatory activities of ILE were evaluated in murine RAW 264.7 macrophages, using lipopolysaccharide (LPS) stimulation. ILE treatment-related changes in the production of nitric oxide (NO), prostaglandin E-2 (PGE(2)), and proinflammatory cytokines were also measured. Finally, the expression of signaling molecules involved in inflammatory reactions was also assessed. Pretreatment of macrophages with ILE attenuated the expression of inducible NO synthase and cyclooxygenase-2, resulting in a decrease in NO and PGE(2) production. The secretion of proinflammatory cytokines such as interleukin (IL)-6 and IL-1 beta was also reduced. Furthermore, ILE reduced extracellular signal-regulated kinases (ERK) phosphorylation, without affecting the inhibitor of kappa B alpha and other mitogen-activated protein kinases. Liquid chromatography-tandem mass spectrometry analysis (LC-MS/MS) demonstrated that 1 g of ILE contains 27 mg of kaempferol, 0.3 mg of vanillic acid, and 21 mg of combined amount of isoquercetin and hyperin, among which isoquercetin and kaempferol significantly suppressed IL-6, IL-1 beta, and PGE(2) production. Our results demonstrated that ILE possesses anti-inflammatory effects mediated through inhibition of ERK phosphorylation.