This study investigates ultrasound assisted extraction (UAE) process parameters (time, frequency and solvent) to obtain high yields of phlorotannins, flavonoids, total phenolics and associated antioxidant activities from 11 brown seaweed species. Optimised UAE conditions (35 kHz, 30 min and 50% ethanol) significantly improved the extraction yield from 1.5-fold to 2.2-fold in all seaweeds investigated compared to solvent extraction. Using ultrasound, the highest recovery of total phenolics (TPC: 572.3 ± 3.2 mg gallic acid equivalent/g), total phlorotannins (TPhC: 476.3 ± 2.2 mg phloroglucinol equivalent/g) and total flavonoids (TFC: 281.0 ± 1.7 mg quercetin equivalent/g) was obtained from Fucus vesiculosus seaweed. While the lowest recovery of TPC (72.6 ± 2.9 mg GAE/g), TPhC (50.3 ± 2.0 mg PGE/g) and TFC (15.2 ± 3.3 mg QE/g) was obtained from Laminaria digitata seaweed. However, extracts from Fucus serratus obtained by UAE exhibited the strongest 1,1-diphenyl-2-picryl-hydrazyl (DPPH) scavenging activity (29.1 ± 0.25 mg trolox equivalent/g) and ferric reducing antioxidant power (FRAP) value (63.9 ± 0.74 mg trolox equivalent/g). UAE under optimised conditions was an effective, low-cost and eco-friendly technique to recover biologically active polyphenols from 11 brown seaweed species.

β-Glucans have been identified as natural biomolecules with immunomodulatory activity. The first objective of the present study was to compare the effects of purified β-glucans derived fromLaminariadigitata,L. hyperboreaandSaccharomyces cerevisiaeon piglet performance, selected bacterial populations and intestinal volatile fatty acid (VFA) production. The second aim was to compare the gene expression profiles of the markers of pro- and anti-inflammation in both unchallenged and lipopolysaccharide (LPS)-challenged ileal and colonic tissues. β-Glucans were included at 250 mg/kg in the diets. The β-glucans derived fromL. hyperborea,L. digitataandS. cerevisiaeall reduced the Enterobacteriaceae population (P < 0·05) without influencing the lactobacilli and bifidobacteria populations (P>0·05) in the ileum and colon. There was a significant interaction between gastrointestinal region and β-glucan source in the expression of cytokine markers, IL-1α (P < 0·001), IL-10 (P < 0·05), TNF-α (P < 0·05) and IL-17A (P < 0·001). β-Glucans did not stimulate any pro- or anti-inflammatory cytokine markers in the ileal epithelial cells. In contrast, the expression of a panel of pro- and anti-inflammatory cytokines (IL-1α,IL-10,TNF-αandIL-17A) was down-regulated in the colon following exposure to β-glucans from all the three sources. However, the data suggest that the soluble β-glucans derived fromL. digitatamay be acting via a different mechanism from the insoluble β-glucans derived fromL. hyperboreaandS. cerevisiae, as the VFA profile was different in theL. digitata-treated animals. There was an increase inIL-8gene expression (P < 0·05) in the gastrointestinal tract from the animals exposed toL. digitatafollowing an LPSex vivochallenge that was not evident in the other two treatment groups. In conclusion, β-glucans from both seaweed and yeast sources reduce Enterobacteriaceae counts and pro-inflammatory markers in the colon, though the mechanisms of action may be different between the soluble and insoluble fibre sources.

The main objective was to determine the chemical, phytochemical, fatty acid and mineral profiles of three commercially relevant brown macroalgae (Laminaria digitata, Laminaria hyperborea and Ascophyllum nodosum) collected each season for two years off the west coast of Ireland. All the chemical, phytochemical, fatty acid and minerals analysed varied significantly depending on the macroalgal species, season and year of collection. Overall, the protein contents of macroalgae were negatively correlated with carbohydrate content. Protein (2–11%) was at its highest during winter and/or spring, decreasing to a minimum during summer and/or autumn. The three macroalgal species analysed in this study had clearly differentiated fatty acid profiles. The concentration of fatty acids was higher in A. nodosum compared with both Laminaria species. The mineral profile of the three macroalgal species was rich in essential metals, particularly Ca, Mg and P, while the levels of I were approximately 9- to 10-fold higher in both Laminaria spp. compared with A. nodosum. The levels of toxic metals (Cd, Hg and Pb) in all the macroalgal species studied were low in the current study; while the levels of total As were high (49–64 mg/kg DW macroalgae) compared with previous reports.

A 2 × 2 factorial experiment was conducted to investigate the interactions between laminarin (LAM; 0 and 300 parts per million (ppm)) and fucoidan (FUC; 0 and 240 ppm) levels on intestinal morphology, selected microbiota and inflammatory cytokine gene expression in the weaned pig. There was an interaction between LAM and FUC supplementation on the Enterobacteriaceae population (P< 0·05) and the abundance of attaching and effacingEscherichia coli(AEEC) strains (P< 0·05) in the colon. Pigs offered the FUC diet had a reduced Enterobacteriaceae population compared with pigs offered the basal diet. However, the effect of FUC on the Enterobacteriaceae population was not observed when combined with LAM. Pigs offered the LAM diet had reduced abundance of AEEC strains compared with pigs offered the basal diet. However, there was no effect of LAM on the abundance of AEEC strains when combined with FUC. There was an interaction between LAM and FUC supplementation on villous height (P< 0·01) and the villous height:crypt depth ratio (P< 0·01) in the duodenum. Pigs offered the LAM or FUC diet had an increased villous height and villous height:crypt depth ratio compared with pigs offered the basal diet. However, there was no effect of the LAM and FUC combination diet on intestinal morphology. Pigs offered the LAM-supplemented diets had a lowerIL-6(P< 0·05),IL-17A(P< 0·01) andIL-1β(P< 0·01) mRNA expression in the colon compared with pigs offered the diets without LAM. In conclusion, supplementation with either LAM or FUC alone modified intestinal morphology and selected intestinal microbiota, but these effects were lost when offered in combination.