Suppression of Inflammatory Responses by Black Rice Extract in RAW 264.7 Macrophage Cells via Downregulation of NF-kB and AP-1 Signaling Pathways

Abstract

Anthocyanin, a phenolic compound, has been reported to have an anti-inflammatory effect againstlipopolysaccharide (LPS) induced changes in immune cells. However, little is known about the molecularmechanisms underlying its anti-inflammatory effects. Few research studies have concerned the anti-inflammationproperties of colored rice extract as a functional material. Therefore, the purpose of this study was to examineanti-inflammatory effects of the polar fraction of black rice whole grain extracts (BR-WG-P) that featuresa high anthocyanin content. Our results showed that BR-WG-P significantly inhibited LPS-induced proinflammatorymediators, including production of NO and expression of iNOS and COX-2. In addition, secretionof pro-inflammatory cytokines including TNF-α and IL-6 was also significantly inhibited. Moreover, BR-WG-Pand anthocyanin inhibited NF-kB and AP-1 translocation into the nucleus. BR-WG-P also decreased thephosphorylation of ERK, p38 and JNK in a dose dependent manner. These results suggested that BR-WG-Pmight suppress LPS-induced inflammation via the inhibition of the MAPK signaling pathway leading to decreaseof NF-kB and AP-1 translocation. All of these results indicate that BR-WG-P exhibits therapeutic potentialassociated with the anthocyanin content in the extract for treating inflammatory diseases associated with cancer.