ABSTRACT
Mulberry leaf protein is a potentially functional food component and health care agent with antioxidant and anti-inflammatory properties. However, its composition, immunoregulatory effects, and gut microbial regulatory effects are unclear. Herein, ultra-filtrated and gel-fractionated mulberry leaf protein (GUMP) was characterized. Its effects on cyclophosphamide-induced immunosuppressed mice were further investigated. The results indicated that GUMP is a glycoprotein mainly containing glucose, arabinose, and mannose with 9.23% total sugar content. Its secondary structure is mainly ß-sheet. LC-MS/MS analysis showed that GUMP closely matched with a 16.7 kDa mannose-binding lectin and a 52.7 kDa Rubisco's large subunit. GUMP intervention significantly improved serous TNF-α, IL-6, and IL-2 contents; increased serum immunoglobulins (IgA and IgG) levels; and reversed splenic damage prominently. Moreover, GUMP administration increased fecal shot-chain fatty acid concentration and up-regulated the relative abundance of Odoribacter, which was positively correlated with SCFAs and cytokine contents. Overall, GUMP alleviated immunosuppression through the integrated modulation of the gut microbiota and immune response. Therefore, GUMP could be a promising dietary supplement to help maintain gut health.
ABSTRACT
To improve the antioxidant efficiency of mulberry leaf protein (MLP), alcalase, protamex, papain, flavourzyme, neutrase, and trypsin were used to hydrolyze MLP. The yield of soluble peptides, secondary structures, molecular weight distributions, and antioxidant activities of MLP hydrolysates (MLPHs) were investigated. Results showed that the native MLP was rich in the fraction above 6.5 kDa and was mainly composed of ß-sheets, while MLPHs were abundant in the fractions of 0.3-0.6 kDa and 0.6-6.5 kDa and were mainly composed of disordered coils and ß-folds. Limited hydrolysis of MLP could lead to better antioxidant activity than extensive hydrolysis. After enzymatic hydrolysis, the content of total sugar and total phenol in MLP increased significantly. MLP hydrolysates prepared with neutrase, alcalase, and protamex were preferable to other enzymes. Meanwhile, an enzyme to substrate level of 1% and a hydrolysis time of 2 hr were the optimum conditions to obtain higher antioxidant hydrolysates using neutrase.
ABSTRACT
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.