Sargaquinoic acid attenuates inflammatory responses by regulating NF-κB and Nrf2 pathways in lipopolysaccharide-stimulated RAW 264.7 cells

Myagropsis myagroides, a brown alga, showed strong anti-inflammatory activities in the previous studies. In this study, we isolated a strong anti-inflammatory compound, sargaquinoic acid (SQA), from M. myagroides and investigated the anti-inflammatory action using lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. SQA suppressed the production of inducible nitric oxide synthase and cyclooxygenase-2 in LPS-stimulated cells as well as that of reactive oxygen species. As a result, SQA inhibited the production of NO, prostaglandin E-2, and proinflammatory cytokines. LPS-induced transcriptional activation of nuclear factor-kappa B (NF-kappa B) was remarkably inhibited by SQA treatment through the prevention of inhibitor kappa B-alpha degradation. The regulation of NF-kappa B activation was also mediated by the phosphorylation of ERK and Akt in LPS-stimulated RAW 264.7 cells. Moreover, SQA induced the production of heme oxygenase 1 via activation of transcription factor Nrf2. These results indicate that SQA inhibits the LPS-induced expression of inflammatory mediators via suppression of ERK and Akt-mediated NF-kappa B pathway as well as up-regulation of Nrf2/HO-1 pathway, indicating that SQA has a potential therapeutic and preventive application in various inflammatory diseases. (C) 2015 Elsevier B.V. All rights reserved.