Egg yolk phosphatidylcholine alleviates DSS-induced colitis in BALB/c mice.

Ulcerative colitis (UC) is a common inflammatory bowel disease, whose incidence is on the rise worldwide. The drugs commonly used for UC are often associated with a number of side effects. Therefore, the development of effective, food-borne substances for UC is in line with the current needs. Egg yolk phosphatidylcholine (EYPC) is one of the abundant lipids in egg yolk and possesses various biological activities. However, its protective effect against UC has not been clarified. In this study, the anti-UC activity of EYPC was investigated using a dextran sodium sulfate (DSS)-induced colitis model of BALB/c mice. The results showed that EYPC supplementation inhibited DSS-induced colon shortening, the spleen index and disease activity index increase and intestinal structural damage. EYPC could down-regulate the levels of TNF-α, IL-1ß, IL-6 and MPO in the colon and restore the number of goblet cells and the level of tight junction (TJ) proteins. Besides, EYPC modulated the composition of the gut microbiota, lowered the relative abundance of the pathogenic bacterium Parabacteroides and upregulated the abundance of the beneficial bacteria Alistipes and Lachnospiraceae_NK4A136_group. These results evidenced that EYPC could attenuate DSS-induced colitis in mice and had the potential to prevent and treat UC.

Improving the gel properties of salted egg white/cooked soybean protein isolate composite gels by ultrasound treatment: Study on the gelling properties and structure.

In this study, the effects of ultrasound treatment on the texture, physicochemical properties and protein structure of composite gels prepared by salted egg white (SEW) and cooked soybean protein isolate (CSPI) at different ratios were investigated. With the increased SEW addition, the ζ-potential absolute values, soluble protein content, surface hydrophobicity and swelling ratio of composite gels showed overall declining trends (P < 0.05), while the free sulfhydryl (SH) contents and hardness of exhibited overall increasing trends (P < 0.05). Microstructural results revealed that composite gels exhibited denser structure with the increased SEW addition. After ultrasound treatment, the particle size of composite protein solutions significantly decreased (P < 0.05), and the free SH contents of ultrasound-treated composite gels were lower than that of untreated composite gels. Moreover, ultrasound treatment enhanced the hardness of composite gels, and promoted the conversion of free water into non-flowable water. However, when ultrasonic power exceeded 150 W, the hardness of composite gels could not be further enhanced. FTIR results indicated that ultrasound treatment facilitated the composite protein aggregates to form a more stable gel structure. The improvement of ultrasound treatment on the properties of composite gels was mainly by promoting the dissociation of protein aggregates, and the dissociated protein particles further interacted to form denser aggregates through disulfide bond, thus facilitating the crosslinking and reaggregation of protein aggregates to form denser gel structure. Overall, ultrasound treatment is an effective approach to improve the properties of SEW-CSPI composite gels, which can improve the potential utilization of SEW and SPI in food processing.

Improvement of gel properties and digestibility of the water-soluble polymer of tea polyphenol-egg white under thermal treatment.

In this study, the improvement of gel properties and digestibility of the water-soluble polymer of tea polyphenol (TP)-egg white protein (TEP) under heat induction (HTEP), was studied. Results indicated that the particle size and turbidity of TEP increased with TP concentration, and the absolute value of ζ-potential decreased. After heat induction, the surface hydrophobicity of HTEP decreased with TP concentration, and the degree of protein aggregation increased. Microstructure and T2 showed that the gel structure became compact and stable, and HTEP had a strong water-binding ability. The ionic and disulfide bonds were the main chemical bonds in HTEP. The hardness and disulfide bond increased, but the digestion of HTEP increased initially and then decreased (caused by the change of gel structure). Infrared spectroscopy indicated the mutual conversion of intermolecular and intramolecular ß-sheets. In short, TP could modify egg white gel through forming stable disulfide bonds and dense gel network structures.

Effects of stewing with tea polyphenol on the gel properties, microstructure, and secondary structure of boiled egg white.

This study aimed to investigatethe mechanism of stewing with tea polyphenols (TP) on the properties of boiled egg white gel (BEWG). The results indicated that, during the stewing process, soluble protein and hardness showed an overall increasing trend, while surface hydrophobicity showed a decreasing trend with blue-shift. The free sulfhydryl group showed that TP could promote the formation of disulfide bonds, and the position of immobilized water at T2 showed a decreasing trend. Environmental scanning electron microscopy and SDS-PAGE showed that the protein gel aggregation degree increased. Moreover, Fourier transform infrared spectrometry showed that protein polarity increased and that α-helices, ß-turn, intramolecular ß-sheets, as well as intermolecular antiparallel ß-sheets showed an increasing trend. Generally, TP strengthened protein aggregation by promoting the formation of disulfide and hydrogen bonds, thus enhancing the gel strength of BEWG. Moreover, the secondary structure of proteins became more stable under the action of TP, and the higher the concentration of TP, the greater the effect on BEWG. PRACTICAL APPLICATION: TP, an ideal, cheap, and safe natural food additive, can be applied to the processing of egg products because the addition of TP can significantly improve the gel strength of egg white.

Egg yolk oils exert anti-inflammatory effect via regulating Nrf2/NF-κB pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Egg yolk oils (EYO) is a traditional Chinese medicine obtained from Gallus gallus domesticus Brisson, which has been used to treat inflammatory related diseases such as cheilitis, ulceration and acute anal fissure. However, the detailed anti-inflammatory mechanism of EYO is still unknown. AIM OF THE STUDY: The anti-inflammatory activity and mechanism of EYO were investigated in tumor necrosis factor (TNF)-α induced Caco-2 cells. MATERIALS AND METHODS: EYO was obtained by direct-heat extraction (HE), ethanol extraction (EE) and petroleum ether extraction (PE), respectively. Fatty acid compositions of three EYO were measured by gas chromatography (GC). Cell viability, enzyme-linked immunosorbent assay (ELISA), transcriptome, RT-PCR and Western blotting were also performed. RESULTS: Fatty acid compositions of three EYO were different with varied extraction methods. EYO significantly reduced interleukin (IL)-8 secretion. EYO exerted anti-inflammatory effect via coordinating regulation of Nrf2/NF-κB pathways based on the results of transcriptome, Q-PCR and Western blotting. In detail, PE and HE inhibited the NF-κB pathway, whereas EE exerted anti-inflammatory activity via the Nrf2/NF-κB pathways. CONCLUSIONS: The aforementioned results showed the anti-inflammatory mechanism of EYO. These findings might be beneficial to clinical applications of EYO.

Isolation and identification of peptides from simulated gastrointestinal digestion of preserved egg white and their anti-inflammatory activity in TNF-α-induced Caco-2 cells.

Simulated gastrointestinal digestion of preserved egg white (SGD-PEW) exerts anti-inflammatory effects on Caco-2 cells and a mouse model of DSS-induced colitis. Here, we aimed to separate peptides derived from SGD-PEW and evaluate their anti-inflammatory effects using an in vitro inflammatory model. Six peptides were isolated and identified. DEDTQAMPFR (DR-10), DEDTQAMPF (DF-9), MLGATSL (ML-7) and MSYSAGF (MF-7) significantly inhibited IL-8 secretion and markedly decreased gene expression, including TNF-α, IL-8, IL-6, IL-1ß and IL-12 and promoted IL-10 gene expression in Caco-2 cells. DR-10, DF-9, ML-7 and MF-7 significantly inhibited the phosphorylation of JNK. In the meantime, DR-10 and DF-9 significantly reduced the phosphorylation of IκB and p38. These results indicated that ML-7 and MF-7 exerted their anti-inflammatory activity through the MAPK signaling pathway in TNF-α-induced Caco-2 cells. Whereas, DR-10 and DF-9 inhibited the NF-κB and MAPK signaling pathways. The results suggested that DR-10, DF-9, ML-7 and MF-7 derived from SGD-PEW may be a new type of prophylactic food for the treatment of inflammation.