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Tyrosinase is the rate-limiting enzyme controlling the production of melanin, and tyrosinase inhibitors can regulate the overproduction of melanin by inhibiting tyrosinase activity, which is an effective method to treat...

In the present study, antioxidant activities and functional properties of cowhide collagen antioxidant peptides (CCAPs) with different molecular weight (MW) were investigated. The optimum preparation conditions of CCAPs were hydrolysis time of 1.53 hr, temperature of 54.9 °C, pH 7.38, and neutral enzyme to trypsin ratio of 0.048 g: 0.016 g according to single factor test and response surface methodology (RSM). Three fractions (CCAP‐I, CCAP‐II, and CCAP‐III) were obtained by ultrafiltration and lyophilization. Antioxidant activities revealed that CCAP‐III had high reducing power activity (0.323 ± 0.035) and scavenging effect on 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radicals (64.30 ± 5.99%), 2,2‐azino‐bis‐(3‐ethylbenzothiazoline)‐6‐sulfonic acid (ABTS) radicals (75.25 ± 3.14%), and hydroxyl radicals (68.26 ± 6.74%) compared to the other fractions. In addition, LC‐MS/MS analysis showed that Ala‐Gly‐Glu‐Arg, Gly‐Ile‐Ala‐Gly‐Glu‐Arg, Gly‐Pro‐Ala‐Gly‐Pro‐Ala‐Gly‐Pro‐Arg, Gly‐Val‐Val‐Gly‐Pro‐Glu‐Gly‐Ala‐Arg and Gly‐Phe‐Ser‐Gly‐Leu‐Asp‐Gly‐Ala‐Lys were the major peptides of CCAP‐III. CCAP‐III showed good hygroscopicity (HYG), water holding capacity (WHC), and oil holding capacity (OHC) when compared with CCAP‐I and CCAP‐II. However, CCAP‐II has great emulsifying properties, and CCAP‐I has excellent foaming properties. Therefore, CCAPs can be used as a promising source of functional peptides with antioxidant properties. Practical Application This study demonstrated the peptides of cowhide collagen has superior antioxidant and functional properties. This study provided a scientific basis for the preparation of antioxidant peptides from cowhide collagen.

Tea Polyphenols (TP) has received much attention for their excellent antioxidant and antibacterial activities. Some additives (such as sodium alginate and sodium pyrophosphate) have good hydrophobicity which have influence on the mechanical properties of food. The effect of TP on the antibacterial activity of collagen casing was investigated, the effect of addition of TP, sodium pyrophosphate and sodium alginate on mechanical properties including tensile force, tensile strength and elongation at break were also studied. Results from the single factor experiments demonstrated that TP showed strong antibacterial activities against Escherichia coli, Staphylococcus aureus and Salmonella according to the Minimum Inhibitory Concentration (MIC) and the inhibition zone method. Moreover, the mechanical properties of collagen casings were obviously influenced by the addition of TP and two food additives including sodium alginate and sodium pyrophosphate. This work would be useful for application of collagen casings with TP in food package to extend shelf-life of sausage during processing, transportation and storage.

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Thioesterases play an essential role in the metabolism of fatty acids since they are considered one of the key enzymes to change the total amount and composition of fatty acid in an organism’s cells. Acyl-coenzyme A thioesterase 8 (ACOT8) exhibits substrate specificity mainly for short- to long-chain acyl-CoA. To identify and characterize the ACOT8 enzyme’s superfamily in Mucor circinelloides, three genes were characterized and homologously expressed in M. circinelloides WJ11 which has been used as a model organism to investigate the mechanism of lipid accumulation. Multiple sequence alignment showed that McACOT8s had significant conserved motifs in the ACOT8 family. Experimental data indicated that the biomass of the three recombinant strains (McACOT8a, McACOT8b and McACOT8c) was slightly lower than that of the control strain Mc2075, but the total fatty acid (TFA) content was significantly increased by 30.3, 21.5 and 23.9%, respectively, and the free fatty acid production increased from 12.9% (control strain) to 19.2, 25.2 and 26.2% (recombinant types), respectively, with a maximum increase of 103.1% in McACOT8c. The three strains did not show any significant improvement in fatty acid composition compared to the control strain. However, in terms of fatty acid composition of free fatty acid, McACOT8b and McACOT8c contained γ-linolenic acid (C18:3), which was not detected in the control strain or in McACOT8a, indicating that ACOT8b and ACOT8c had substrate specificity for C18:3. These results displayed that ACOT8 can increase TFA accumulation and that it may be an important target of genetic manipulation for microbial oil production.

In this paper, we studied the inhibitory effect of crude Walnut Leaf Polysaccharides (WLP) on free radical-induced oxidative damage of proteins and anti-proliferation activity on human Gastric Cancer cells (SGC-7901). The oxidative degradation of Bovine Serum Albumin (BSA), mouse brain proteins (MBP) and Mouse Liver Proteins (MLP) induced by hydroxyl radical and alcoxyl radical was analyzed by Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE). In addition, MTT method was used to analyze the effect of WLP on cell viabilities of SGC-7901 cells. The results indicated that WLP significantly inhibited the oxidative damage of BSA induced by hydroxyl radical within the concentration range of 0.5~20 mg/mL. Similar protective effects were found in hydroxyl radical-induced oxidative damage on mouse tissue proteins. WLP inhibited the oxidative damage of three protein models induced by alcoxyl radical in a dose-dependent manner. Furthermore, WLP inhibited the growth of SGC-7901 cells in time-and concentrationdependent manner. In conclusion, WLP show significant inhibitory effect on protein oxidative damage induced by hydroxyl radical and alcoxyl radical as well as anti-proliferation capacity on SGC-7901 cells.

In this paper, we studied the inhibitory effect of oleanolic acid (OA) on non-enzymatic glycosylation and the improvement of glycometabolism in insulin resistant (IR) human liver tumour (HepG2) cells. The anti-glycosylation activity of OA was determined by bovine serum albumin (BSA) fructose model. The results showed that OA moderately inhibited the formation of the intermediates of non-enzymatic glycosylation, fructosamine and α-dicarbonyl compounds, and strongly inhibited the formation of advanced glycation end products (AGEs). In addition, we analysed the effect of OA on glycometabolism induced by palmitic acid (PA) in HepG2 cells. The results showed that OA had almost no impact on HepG2 cell viability at concentrations lower than 30 µM. With the increase of OA concentration, glucose production in IR HepG2 cells decreased, while glycogen content increased. Meanwhile, OA has a significant inhibitory effect on reactive oxygen species (ROS) levels in IR-HepG2 cells. Those results suggested that OA could be a promising natural blood glucose decreasing substance in the pharmaceutical and functional food industries.