Garlic polysaccharides are great potential agents because of their anti-inflammation, antioxidation, and immunomodulation properties. However, few studies have reported their anti-inflammatory effects on improving the colon system and corresponding intestinal microbiota. Herein, a water-soluble garlic polysaccharide (WSGP) was extracted from Jinxiang garlic to evaluate its effects on ameliorating dextran sulfate sodium (DSS)-induced colitis in a mouse model. The results showed that (1) after administration of the WSGP (200 or 400 mg/kg/day), the feed intake, body weight, and colon length of colitic mice were increased, while the disease activity index and the histological score of colitic mice were decreased; (2) the WSGP reduced the colonic tissue damage and inhibited the expression of inflammatory factors (interleukin 6, interleukin 1 beta , and tumor necrosis factor alpha); and (3) the WSGP enhanced the production of short-chain fatty acids and improved the composition of intestinal microbiota. The key microorganisms, including Muribaculaceae, Lachnospiraceae, Lachnospiraceae_NK4A136_group, Mucispirillum, Helicobacter, Ruminococcus_1, and Ruminiclostridium_5, were identified to be associated with inflammatory bowel diseases. Taken together, this study proved that WSGP supplementation could alleviate DSS-induced colitis by improving mucosal barriers, blocking proinflammatory cytokines, and modulating gut microbiota.

Neutrase-hydrolysates hydrolyzed from mulberry leaf proteins were separated by ion exchange chromatography, gel filtration chromatography, and semipreparative reverse-phase HPLC. Purified fractions were analyzed for their radical scavenging activity, hemolysis inhibition ability, and cellular antioxidant activity (CAA). Three new antioxidant peptides, P1 (SVL, 317 Da), P2 (EAVQ, 445 Da), and P3 (RDY, 452 Da), were obtained from the most active HPLC fraction (R1) and identified using UPLC-QTOF-MS. These three peptides were then synthesized, and their antioxidant activities were analyzed. P1 and P2 had no ability to inhibit hemolysis of erythrocytes but did show antioxidant activity on HepG2 cells. P3 showed the highest hemolysis inhibition ability (92%) and CAA value (2204 μM QE/100 g peptide). The Tyr residues at the C-terminal region play an important role in the antioxidant activity in P3. Thus, the natural peptide R1 and synthesized P3 could be used as antioxidants and might be promising components of functional foods.

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Summary Defatted wheat germ globulin (DWGG) was hydrolysed using the enzymes alcalase, neutrase, papain, pepsin or trypsin to improve the immunomodulatory effects of the protein. The degree of hydrolysis (DH), molecular weight distribution, hydrophobicity, secondary structures and immunomodulatory activities were determined. The DH of hydrolysate using alcalase or neutrase was higher (P < 0.05) than that of hydrolysate prepared by other proteases. Alcalase hydrolysate (AH) had the strongest (P < 0.05) immunomodulatory activity with respect to lymphocyte proliferation, phagocytosis of neutral red and secretion of pro‐inflammatory cytokines. The molecular weight of AH ranged between 300 and 1450 Da and was composed of α‐helix and β‐turns. AH also showed the highest hydrophobic value (P < 0.05). The DH and hydrophobicity appear to be related to immunomodulatory activities. The hydrolysate prepared by the alcalase treatment on DWGG may be used as an immune supplement by the food industry.

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Summary Wheat bran was fermented at 28 °C for 7 days under 70% humidity by Aspergillus niger, Aspergillus oryzae and Aspergillus awamori. Total phenolic content (TPC) of the unfermented sample was 1531.5 μg g−1 wheat bran. After the fermentation of Aspergillus awamori, Aspergillus oryzae and Aspergillus niger, TPC reached 5362.1, 7462.6 and 10 707.5 μg g−1, respectively. The antioxidant activity in the extractions of fermented wheat bran also increased significantly compared with the unfermented sample (P < 0.05). Aspergillus niger showed the greatest capacity to release bound ferulic acid (416.6 μg g−1). Aspergillus oryzae and Aspergillus awamori had the advantages of releasing more chlorogenic acid (84.0 μg g−1) and syringic acid (142.3 μg g−1), respectively. The destructive effect of Aspergillus niger on wheat bran structure was the strongest, followed by that of Aspergillus oryzae. This effect of Aspergillus niger may be due to its higher cellulase, xylanase, arabinofuranosidase and β‐xylosidase activities. Besides, Aspergillus oryzae possessed higher β‐glucosidase activity, and Aspergillus awamori had higher α‐amylase and feruloyl esterase activities. Aspergillus niger may be the best to release bound phenolic acids in the three Aspergillus species. These will provide the helpful information for understanding mechanism of the fermentation by Aspergillus species releasing bound phenolic in wheat bran.

Summary DA‐P, fraction of peptides with a molecular weight <1 kDa isolated from Dendrobium aphyllum, was analysed in three types of cell lines to verify its bioactivity and absorptivity. The cellular antioxidant activity of DA‐P in HepG2 cells was used and results revealed an EC50 of 2.88 ± 0.143 mg mL−1 and a CAA unit of 63.46 ± 2.11 μm QE/100 g peptides. DA‐P treatment enhanced the secretion of cytokines in RAW 264.7 cells. After demonstrating the presence of tight junctions in Caco‐2 monolayers, the absorption was 25.57% ± 0.016% and 19.7% ± 0.012% from different sides. The relatively high absorption indicated that the antioxidant‐relevant immune functions of DA‐P had a greater possibility to be absorbed by Caco‐2 cells. Free amino acids and LC‐MS/MS analysis indicated the degradation and expulsion of components after the absorption of DA‐P, and Ser‐Ser‐Arg was able to come across the monolayers.

Summary Proteins and peptides must be degraded and modified in the gastrointestinal (GI) tract prior to absorption; this process changes their physicochemical and biological properties. Mulberry leaf protein (MP) and its hydrolysates (HMP) have favourable antioxidant activities. To investigate, in vitro and separately, the effects of GI digestion and intestinal digestion on the stability of MP and HMP, we monitored the changes in secondary structures, amino acids, molecular weights and antioxidant activities. We found that MP was more hydrolysed by pepsin than by pancreatin, unlike HMP. The final digests of MP and HMP were mainly composed of polypeptides (0.5–6.5 kDa) and oligopeptides (<0.5 kDa), respectively. The GI digestion influenced MP and HMP differently; GI digestion increased the antioxidant efficiency of MP and decreased that of HMP. For the intestinal digests, the antioxidant activities of MP and HMP also differed. The 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) and 2,2′‐azinobis (3‐ethylbenzothiazoline‐6‐sulphonic acid) diammonium salt (ABTS) radical quenching abilities of MP and HMP at 1 mg mL−1 were comparable to or exceeded that of L‐glutathione (GSH) and 6‐hydroxy‐2,5,7,8‐tetramethychroman‐2‐carboxylic acid (trolox). Meanwhile, the erythrocyte haemolysis rates of MP, HMP and their GI products at 0.05–1.0 mg mL−1 were significantly lower than that of the 2,2′‐azobis (isobutyramidine) dihydrochloride (AAPH) control. Both MP and HMP can be used as natural antioxidants and may promote digestive health.