Anti-Inflammatory Effects of Immature Pear Extract through the Regulation of MAPKs Signaling Pathway in LPS-Induced Inflammation in RAW 264.7 Macrophages

Abstract

During the cultivation of pears, the immature pears are thinned out and discarded in large quantities as a by-product. Hence, this study was conducted to find ways to utilize them as a useful resource. The total polyphenol content of the immature pears was about 3.6 times higher than that of mature pears, and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity was about 2 times higher. Specifically, the anti-inflammatory effect of the immature pear extract (IPE) was confirmed in an activated macrophage experimental model. There was no significant change in the cell viability of RAW 264.7 macrophages in the cytotoxicity test wherein IPE was used in the concentration range of 50 to 500 μg/mL. The level of nitric oxide production was significantly reduced along with the decrease in the inducible nitric oxide synthase expression in IPE treated lipopolysaccharides (LPS)-induced inflammation in the macrophages. In addition, the levels of secretion of inflammatory cytokines induced by LPS, such as interleukin (IL)-1β, IL-6, and tumor necrosis factor-α were also reduced. The expression levels of phosphorylated extracellular signal-regulated kinase, phosphorylated Jun N-terminal kinase, and p-p38, which are the major factors inducing inflammation, were reduced. This can be inferred to be the anti-inflammatory effect of IPE caused by a mechanism that inhibits the phosphorylation of factors acting in the mitogen-activated protein kinase (MAPK) pathway. Therefore, IPE could be of commercial value as a new material for use as a healthy functional food and as an anti-inflammatory component for medicinal use.