Anti-inflammatory action of high molecular weight Mytilus edulis hydrolysates fraction in LPS-induced RAW264.7 macrophage via NF-κB and MAPK pathways

Anti-inflammatory Mytilus edulis hydrolysates (MEHs) were prepared by peptic hydrolysis and MEH was further fractionated into three fractions based on molecular weight, namely >5 kDa, 1-5 kDa, and <1 kDa. The >5 kDa peptide fraction exerted the highest nitric oxide (NO) inhibitory activity and inhibited prostaglandin E-2 (PGE(2)) secretion in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Pretreatment with the >5 kDa peptide fraction markedly inhibited LPS-stimulated inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein and gene expressions. Stimulation by LPS induced the production of pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and -1 beta (IL-1 beta), whereas co-treatment with the >5 kDa peptide fraction suppressed proinflammatory cytokine production. The >5 kDa peptide fraction inhibited the translocation of NF-kappa B (nuclear factor-kappa B) through the prevention of I kappa B alpha (inhibitory factor kappa B alpha) phosphorylation and degradation and also inhibited the MAPK signaling pathway in LPS-stimulated RAW264.7 macrophages. (C) 2016 Elsevier Ltd. All rights reserved.