A Leaf Methanolic Extract of Wercklea insignis Attenuates the Lipopolysaccharide-Induced Inflammatory Response by Blocking the NF-κB Signaling Pathway in RAW 264.7 Macrophages

Abstract

The biological activity of Wercklea insignis (WI) in inflammation and the underlying mechanisms of action of extracts of this plant are largely unknown. In the present study, we investigated the effects of a WI methanolic extract on lipopolysaccharide-stimulated inflammation in the mouse macrophage cell line, RAW 264.7. A WI methanolic extract significantly inhibited NO, PGE(2), IL-6, IL-1β, and TNF-α production in LPS-stimulated RAW 264.7 cells. Expression of iNOS, COX-2, IL-6, IL-1β, and TNF-α were suppressed by the extract at both the mRNA and protein levels in lipopolysaccharide (LPS)-stimulated cells. Additionally, the attenuation of inflammatory responses in RAW 264.7 cells by the WI extract was closely associated with suppression of phosphorylation of mitogen-activated protein kinase (MAPK) molecules, including ERK, JNK1/2, and p38 MAPK and translocation of the nuclear factor (NF)-κB p65 subunit into the nucleus. The effect of WI extract was investigated against carrageenan-induced paw edema in female (20-25 g). Our results collectively indicate that the WI extract inhibits LPS-induced inflammatory responses by blocking the NF-κB signaling pathway in macrophages, supporting use of the extract as a therapeutic anti-inflammatory treatment.