A comparison of the effects of an Ascophyllum nodosum ethanol extract and its molecular weight fractions on the inflammatory immune gene expression in-vitro and ex-vivo

•Extracts of Ascophyllum nodosum exhibited anti-inflammatory bioactivity in Caco-2 cells.•EE inhibited NF-κB mediated pro-inflammatory pathways in-vitro and ex-vivo.•EE and its MW fractions inhibited the expression of pro-inflammatory genes ex-vivo.•Crude EE exhibited the most potent anti-inflammatory bioactivity via TLR4.

The anti-inflammatory bioactivities of three crude extracts of Ascophyllum nodosum (cold water, hot water and 80% ethanol extract (EE)) were initially evaluated. Following from this, the immune modulatory efficacy of EE and its MW fractions (< 3.5, 3.5-100, > 100 kDa) were compared. In TNF-α challenged Caco-2 cells, the crude extracts reduced IL-8 production (P < 0.001), while the EE caused a > 2 fold down-regulation of; cytokines (IL8, TNFA, IL1B, IL18 and CSF1) chemokines (CXCL10 and CCL5), components of NF-κB pathway (NFKB2 and IKBKB), and inflammatory mediators (PTGS2 and MIF) genes. In the porcine colonic tissue ex-vivo challenged with lipopolysaccharide, EE and its MW fractions down-regulated the immune related targets LYZ, IL8, PTGS2, TLR6, CXCL10, IL6, CXCL11, ICAM, NFKB1 and CXCL2. It was concluded that while the MW fractionation potentially generated compounds displaying distinct immune modulatory functions, the crude EE exhibited the most potent immunomodulatory bioactivity.Industrial relevanceThe result demonstrated that the fractionation of crude 80% ethanol extract of A. nodosum into MW fractions potentially separate bioactive compounds with distinct immune modulatory function. The crude extract exhibited the most potent immunomodulatory bioactivity in Caco-2 cells challenged with TNF-α and in the porcine colonic tissue challenged with LPS. Such a broad spectrum anti-inflammatory bioactivity of A. nodosum ethanol extract can be further explored for its potential application in inflammatory diseases of the mammalian intestine.