Shigeru Katayama

Antioxidant activity of tryptic digests of hen egg yolk phosvitin

BACKGROUND Food protein-derived peptides with antioxidant activity have great potential for use as natural antioxidants in food products. However, neither the structure-activity relationship nor the antioxidant mechanism of peptides is fully understood. Egg yolk phosvitin has been acknowledged to have strongly antioxidant protein owing to its highly phosphorylated form. In this study the antioxidant activities of tryptic digests of hen egg yolk phosvitin (PPPs), which were prepared by partial dephosphorylation and subsequent hydrolysis by trypsin, were compared with that of intact phosvitin. RESULTS Compared with intact phosvitin, PPPs exhibited distinctly stronger capability of inhibiting lipid oxidation in a linoleic acid system and more efficient radical-scavenging activity on 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals. However, the chelating capability of PPPs on iron(II) was weaker than that of intact phosvitin. The strong antioxidant activity of PPPs can be mainly attributed to the amino acid composition rather than to the content of phosphorylserine ligands. Histidine, methionine and tyrosine are the amino acids most likely to be responsible for the strong antioxidant activity of phosvitin peptides. CONCLUSION The present study indicated that PPPs could be used in foods as natural antioxidants with strong antioxidant activity. Copyright

Effects of ovalbumin glycoconjugates on alleviation of orally induced egg allergy in mice via dendritic‐cell maturation and T‐cell activation

SCOPE Glycation of allergens via Maillard reaction or chemical conjugation has been shown to influence susceptibility to food-induced allergies. It is hypothesized that mucosal immune response bias can be favorably altered by orally administering various forms of glycated ovalbumin (OVA). METHODS AND RESULTS Groups of Balb/c mice (n = 10) were orally sensitized to OVA and administered various forms of glycated OVA (glucose, mannose, glucomannan, galactomannan, and a mixture containing OVA and glucomannan). Outcomes post oral challenge were measured as clinical allergic signs, serum histamine, mouse mast cell protease 1 (MMCP-1), antibody activity, type-1/2 cytokines, percentage of T-regulatory cells (T-regs) and in vitro dendritic cell, and T-cell-related mechanisms. Clinical signs and specific IgE were decreased (p ≤ 0.05), and T-reg cell percentage was increased in the mannose and glucomannan treated groups. The OVA-mannose group also had less histamine, MMCP-1, specific IgG, IL-4 and IL-17, and more IL-12p70 (p ≤ 0.05). Other parameters measured did not differ significantly among groups. Also, OVA-glycated mannose reduced maturation and uptake by dendritic cells. Less activation of T cells and type-2 cytokine response in DC-T-cell cocultures were observed with OVA-glycated mannose stimulation. CONCLUSION This study validates, for the first time, the use of OVA-glycated mannose and glucomannan for potential beneficial dietary interventions for allergy.

Immunomodulating effects of egg yolk low lipid peptic digests in a murine model

Abstract There is a close link between nutrition and immunity. Bioactive peptides derived from various protein sources have been demonstrated to exert immunomodulating effects. Those activated sequences may also be found in egg yolk. When administered in vivo to chicken, egg yolk digests prevented bacterial infections. Thus, egg yolk low lipid peptic digests’ (EYLLPD) effects were studied in a murine model to elucidate their actions mechanism and immunomodulating capacity. The mucosal immune response was investigated by immunohistochemistry. IL-6 production was evaluated by ELISA. The results show that EYLLPD induces an immune response with an increase in IgA+ cells, while orchestrating the Th1/Th2 response. Furthermore, they reveal a potential role of the epithelium in the effects of EYLLPD at the epithelial surface, as suggested by the increase of the IL-6 secretion by small intestinal epithelial cells (SIEC). In summary, this study shows that EYLLPD enhances mucosal immune responses and that SIEC might have played an important role in preventing the bacterial infection.

Loss of filament-forming ability of myosin by non-enzymatic glycosylation and its molecular mechanism.

Carp and scallop myosin and their subfragments (S‐1 and rod) were reacted with glucose to investigate the effect of non‐enzymatic glycosylation on the functionality of myosin. The filament‐forming ability of the myosin rod diminished with the progress of non‐enzymatic glycosylation and myosin became soluble in 0.1 M NaCl. The inhibition of the self‐assembly of myosin molecules occurred chemically as a result of the increase in negative charge repulsion among myosin molecules and, further, physically as a result of the introduction of the glycosyl units into the surface of the rod region.

Apricot carotenoids possess potent anti-amyloidogenic activity in vitro.

Alzheimers disease (AD) is the most common form of dementia and is characterized by the progressive accumulation of amyloid β protein (Aβ) in areas of the brain. There has been an increased interest in screening for food-grade anti-amyloidogenic compounds in foodstuffs. The purpose of this study was to screen and identify bioactive compounds with anti-amyloidogenicity in apricot fruits using synthetic Aβ(1-42). The anti-amyloidogenicity was investigated using thioflavin T fluorescence assay, electron microscopy, and dot blotting analysis. The carotenoid fraction from apricot showed strong inhibitory effects against oligomer and fibril formation of Aβ and fibril-destabilizing effects. Among the peaks in the HPLC chromatogram, lutein showed the strongest inhibitory effect on Aβ fibril formation. The inhibitory effect was dependent on the number and portion of hydroxyl groups on both sides of carotenoids. These findings suggest that lutein in fruits may be useful as a preventive agent for amyloid-associated diseases.

Antimicrobial effects of chlorogenic acid and related compounds

Chlorogenic acid (CGA) is a natural chemical ester composed of caffeic acid and (-)-quinic acid, and is further metabolized into active compounds in the living body. Here, we aimed to provide fundamental information on the antimicrobial action of CGA and related compounds against the Gram-negative bacterium Escherichia coli IFO 3301. Bacteriostatic effects were assessed by spectrophotometry, and bactericidal effects were determined by enumerating viable cells on MacConkey agar plates. CGA and related compounds exhibited specific antimicrobial activity and corresponding reduction in log survival ratio, in which ferulic, isoferulic, benzoic, and hydroxybenzoic acids exhibited obvious antimicrobial activity against E. coli. In a time-kill assay, it was observed that bactericidal effects were associated with treatment time, temperature, and dose. A reduction in log survival ratio was observed at low pH as well as under thermal stress condition. Thus, we demonstrated that CGA and related compounds have not only bacteriostatic effects but also bactericidal effects.

Attenuation of allergic immune response phenotype by mannosylated egg white in orally induced allergy in BALB/c mice.

Food allergies are attributed to an imbalance in immune response to ubiquitous antigens. A previous study demonstrated that mannose glycation (mannosylation) of ovalbumin decreased allergenicity in vivo. The proposed research targets mannosylation of various common allergens that may help prevent food allergy. Balb/c mice (n = 8) were sensitized toxin egg white, peanut, and whey and treated with mannosylated forms of the test antigens. Glucosylated peanut and cholera toxins were used as controls. Allergic status was assessed as clinical signs, serum histamine, mouse mast cell protease (MMCP), antibody activity, cytokines, and T regulatory cells (T-regs). Significant preventative effects were observed with mannosylated egg white treatment such as reduced clinical signs, histamine, MMCP, specific G, G1, and E antibody activities, and IL-4 and increased IL-10 and CD25(+) Foxp3(+) cells. Other groups did not differ significantly. It was concluded that mannosylated egg white provides a powerful tool to prevent allergic phenotypes with possible relevance to control human egg allergy.

Enzymatic synthesis of novel phenol acid rutinosides using rutinase and their antiviral activity in vitro.

Novel rutinosides of vanillic acid, sinapic acid, ferulic acid, and caffeic acid were prepared via a rutinase-catalyzed transglycosylation reaction. Reaction mixtures containing rutin, phenolic acid, and rutinase derived from tartary buckwheat ( Fagopyrum tataricum ) seeds were incubated in 20 mM acetate buffer (pH 5.0) at 40 °C. The resulting rutinoside of each phenolic acid was purified by HPLC, and the structure was determined by NMR and FAB-MS analysis. Antiviral activity was determined using feline calicivirus (FCV) strain F9, which is a typical norovirus surrogate. It was found that rutinosylation of the phenolic acids increased their antiviral activity against FCV, with the sinapic acid rutinoside being the most effective. These results will contribute to the development of antiviral agents against noroviruses.

Apple polyphenols suppress antigen presentation of ovalbumin by THP-1-derived dendritic cells

Apple polyphenol extract (AP) and procyanidin contained in AP were investigated for their immunomodulatory effects using THP-1-derived human dendritic cells (TDDCs). The expression levels of HLA-DR (MHC class II) and CD86 (costimulatory molecule) were measured as an indicator of antigen presentation in TDDCs. A significant decrease in HLA-DR expression was observed in the AP and fractionated procyanidin-treated cells in the presence of ovalbumin (OVA), but no effect on CD86 expression was observed. The uptake of OVA was not inhibited by AP treatment, and the gene expression of membrane-associated RING-CH ubiquitin E3 ligase, MARCH1, was up-regulated by AP treatment. It can therefore be presumed that AP suppresses HLA-DR expression via the ubiquitin-proteasome pathway. Furthermore, the up-regulation of IL-12 and TNF-α was found in the procyanidin trimers-treated cells in the presence of OVA. These results suggest that apple polyphenols would be an effective factor for the development of immunomodulatory agents with suppressive effects of antigen presentation.

Antioxidative Ability of Chicken Myofibrillar Protein Developed by Glycosylation and Changes in the Solubility and Thermal Stability

Myofibrillar protein prepared from chicken breast muscle was incubated with several concentrations of glucose or maltose for 6 h at 60 °C and 35% relative humidity in order to obtain glycosylated chicken protein. When the ratio of the weights of the myofibrillar protein and glucose or maltose had respectively reached 1:6 or 1:3–5, the solubility of each type of glycosylated chicken protein in a 0.1 M NaCl solution was exceeded by about 60%, although the myofibrillar protein was insoluble in a low ionic strength solution. Moreover, when the myofibril and maltose reaction (myofibril:maltose = 1:4) was extended to 36 h, the glycosylated protein did not undergo denaturation when held at 50 °C for 2 h, while it also exhibited an antioxidative function against superoxide anion radicals.