Purification and identification of adipogenic-differentiating peptides from egg white hydrolysate

Oral administration of PIISVYWK and FSVVPSPK peptides attenuates obesity, oxidative stress, and inflammation in high fat diet-induced obese mice

The bioactive peptides PIISVYWK (P1) and FSVVPSPK (P2), derived from the blue mussel Mytilus edulis, exhibit significant benefits in combating obesity, oxidative stress, and inflammation. This study demonstrates that these peptides inhibit the differentiation of bone marrow-derived mesenchymal stem cells (BMMSCs) into adipocytes by downregulating the adipogenic transcription factors peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer-binding protein alpha (C/EBPα), and sterol regulatory element-binding protein 1 (SREBP-1). Furthermore, P1 and P2 reduce lipogenesis and enhance lipolysis through the activation of AMP-activated protein kinase (AMPK) and hormone-sensitive lipase (HSL). These peptides also decrease intracellular reactive oxygen species (ROS) generation during adipogenesis and inhibit the mitogen-activated protein kinase (MAPK) pathway, thereby reducing inflammation. The involvement of heme oxygenase-1 (HO-1) in this mechanism is confirmed by the reversal of these effects upon HO-1 inhibition. In vivo, oral administration of P1 and P2 in high-fat diet (HFD) obese mice prevents weight gain, reduces adipose tissue accumulation, lowers adipogenic and lipogenic biomarkers, improves serum cholesterol levels, enhances lipolysis, and decreases pro-inflammatory cytokine production. These findings suggest that P1 and P2 peptides may effectively prevent obesity and related metabolic disorders by activating the HO-1/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway.

Gastrointestinal digestion of food proteins: Anticancer, antihypertensive, anti-obesity, and immunomodulatory mechanisms of the derived peptides

Food proteins and their peptides play a significant role in the important biological processes and physiological functions of the body. The peptides show diverse biological benefits ranging from anticancer to antihypertensive, anti-obesity, and immunomodulatory, among others. In this review, an overview of food protein digestion in the gastrointestinal tract and the mechanisms involved was presented. As some proteins remain resistant and undigested, the multifarious factors (e.g. protein type and structure, microbial composition, pH levels and redox potential, host factors, etc.) affecting their colonic fermentation, the derived peptides, and amino acids that evade intestinal digestion are thus considered. The section that follows focuses on the mechanisms of the peptides with anticancer, antihypertensive, anti-obesity, and immunomodulatory effects. As further considerations were made, it is concluded that clinical studies targeting a clear understanding of the gastrointestinal stability, bioavailability, and safety of food-based peptides are still warranted.

Albumen and Yolk Plasma Peptidomics for the Identification and Quantitation of Bioactive Molecules and the Quality Control of Hen Egg Products

Hen eggs and the corresponding food products are essential components of human diet. In addition to supplying basic nutrients, they contain functional peptides that are released in vivo within the intact raw material following physiological proteolytic events affecting specific proteins or derive from technological processing of albumen and yolk fractions as a result of the dedicated use of proteases from plant and microbial sources. Besides their potential importance for functional applications, peptides released under physiological conditions in intact egg can be used as markers of product storage and deterioration. Therefore, characterization and quantitation of peptides in egg and egg-derived products can be used to implement evaluation of potential bioactivities as well as to assess food product qualitative characteristics. Here, we provide dedicated information on extraction, identification, and quantitative analysis of peptides from albumen and yolk plasma; nano-liquid chromatography-mass spectrometry combined with bioinformatic analysis of resulting raw data by different software tools allowed to assign molecules based on database searching and to evaluate their relative quantity in different samples.

Millet Bran Protein Hydrolysate Displays the Anti-non-alcoholic Fatty Liver Disease Effect via Activating Peroxisome Proliferator-Activated Receptor γ to Restrain Fatty Acid Uptake

Non-alcoholic fatty liver disease (NAFLD) is a serious health problem worldwide. Impeding fatty acid uptake may be an attractive therapeutic strategy for NAFLD. In the current study, we found that millet bran protein hydrolysate (MBPH) prepared by in vitro gastrointestinal bionic digestion exhibits the potential of anti-NAFLD in vitro and in vivo, characterized by the alleviation of hepatic steatosis and the reduction of lipid accumulation. Further, MBPH significantly decreased the expression levels of fatty acid uptake related genes (FABP1, FABP2, FABP4, CD36, and CPT-1α) of liver tissue in a NAFLD mice model through activating peroxisome proliferator-activated receptor γ (PPARγ) and efficiently restrained the fatty acid uptake of liver tissue, thus exerting anti-NAFLD activity. As expected, the anti-NAFLD effect induced by MBPH, characterized by the alleviation of hepatic vacuolar degeneration, hepatic steatosis, and fibrosis, was effectively abrogated with PPARγ inhibitor (GW9662) treatment. These results indicate that the retardant of fatty acid uptake induced by PPARγ activation may be the critical factor for the anti-NAFLD effect of MBPH. Collectively, MBPH has the potential as a next-generation dietary supplementation for the prevention and treatment of NAFLD.

An Egg White-Derived Peptide Enhances Systemic Insulin Sensitivity and Modulates Markers of Non-Alcoholic Fatty Liver Disease in Obese, Insulin Resistant Mice

Non-alcoholic fatty liver disease (NAFLD), the hepatic manifestation of the metabolic syndrome, is a global health problem. Currently, no pharmacological treatment is approved for NAFLD. Natural health products, including bioactive peptides, are potential candidates to aid in the management of metabolic syndrome-related conditions, including insulin resistance and obesity. In this study, we hypothesized that an egg-white-derived bioactive peptide QAMPFRVTEQE (Peptide 2) would improve systemic and local white adipose tissue insulin sensitivity, thereby preventing high-fat diet-induced exacerbation of pathological features associated with NAFLD, such as lipid droplet size and number, inflammation, and hepatocyte hypertrophy in high-fat diet-fed mice. Similar to rosiglitazone, Peptide 2 supplementation improved systemic insulin resistance during the hyperinsulinemic-euglycemic clamp and enhanced insulin signalling in white adipose tissue, modulating ex vivo lipolysis. In the liver, compared with high-fat diet fed animals, Peptide 2 supplemented animals presented decreased hepatic cholesterol accumulation (p < 0.05) and area of individual hepatic lipid droplet by around 50% (p = 0.09) and reduced hepatic inflammatory infiltration (p < 0.05) whereas rosiglitazone exacerbated steatosis. In conclusion, Peptide 2 supplementation improved insulin sensitivity and decreased hepatic steatosis, unlike the insulin-sensitizing drug rosiglitazone.

Review on Extraction, Modification, and Synthesis of Natural Peptides and Their Beneficial Effects on Skin

Peptides, functional nutrients with a size between those of large proteins and small amino acids, are easily absorbed by the human body. Therefore, they are seeing increasing use in clinical medicine and have revealed immunomodulatory and anti-inflammatory properties which could make them effective in healing skin wounds. This review sorted and summarized the relevant literature about peptides during the past decade. Recent works on the extraction, modification and synthesis of peptides were reviewed. Importantly, the unique beneficial effects of peptides on the skin were extensively explored, providing ideas for the development and innovation of peptides and laying a knowledge foundation for the clinical application of peptides.

Antioxidant peptides: Overview of production, properties, and applications in food systems

In recent years, several studies have reported the beneficial effects of antioxidant peptides in delaying oxidation reactions. Thus, a growing number of food proteins have been investigated as suitable sources for obtaining these antioxidant peptides. In this study, some of the most critical developments in the discovery of peptidic antioxidants are discussed. Initially, the primary methods to release, purify, and identify these antioxidant peptides from various food-derived sources are reviewed. Then, computer-based screening methods of the available peptides are summarized, and methods to interpret their structure-activity relationship are illustrated. Finally, approaches to the large-scale production of these bioactive peptides are described. In addition, the applications of these antioxidants in food systems are discussed, and gaps, future challenges, and opportunities in this field are highlighted. In conclusion, various food items can be considered promising sources to obtain these novel antioxidant peptides, which present various opportunities for food applications in addition to health promotion. The lack of in-depth data on the link between the structure and activity of these antioxidants, which is critical for the prediction of possible bioactive amino acid sequences and their potency in food systems and in vivo conditions (rather than in vitro systems), requires further attention. Consequently, future collaborative research activities between the industry and academia are required to realize the commercialization objectives of these novel antioxidant peptides.

Food protein-derived bioactive peptides for the management of nutrition related chronic diseases

Dietary intervention via modifications of dietary pattern or supplementations of naturally derived bioactive compounds has been considered as an efficient approach in management of nutrition related chronic diseases. Food protein-derived bioactive peptide is representative of natural compounds which show the potential to prevent or mitigate nutrition related chronic diseases. In the past decades, substantial research has been conducted concentrating on the characterization, bioavailability, and activity assessment of bioactive peptides. Although various activities of bioactive peptides have been reported, the activity testes of most peptides were only conducted in cells and animal models. Some clinical trials of bioactive peptides were also reported but only limited to antihypertensive peptides, antidiabetic peptides and peptides modulating blood lipid profile. Hereby, clinical evidence of bioactive peptides in management of nutrition-related chronic diseases is summarized in this chapter, which aims at providing implications for the clinical studies of bioactive peptides in the future.

Bioactive Peptides: An Understanding from Current Screening Methodology

Bioactive peptides with high potency against numerous human disorders have been regarded as a promising therapy in disease control. These peptides could be released from various dietary protein sources through hydrolysis processing using physical conditions, chemical agents, microbial fermentation, or enzymatic digestions. Considering the diversity of the original proteins and the complexity of the multiple structural peptides that existed in the hydrolysis mixture, the screening of bioactive peptides will be a challenge task. Well-organized and well-designed methods are necessarily required to enhance the efficiency of studying the potential peptides. This article, hence, provides an overview of bioactive peptides with an emphasis on the current strategy used for screening and characterization methods. Moreover, the understanding of the biological activities of peptides, mechanism inhibitions, and the interaction of the complex of peptide–enzyme is commonly evaluated using specific in vitro assays and molecular docking analysis.

IRW (Isoleucine-Arginine-Tryptophan) Improves Glucose Tolerance in High Fat Diet Fed C57BL/6 Mice via Activation of Insulin Signaling and AMPK Pathways in Skeletal Muscle

IRW (Isoleucine−Arginine−Tryptophan), has antihypertensive and anti-inflammatory properties in cells and animal models and prevents angiotensin-II- and tumor necrosis factor (TNF)-α-induced insulin resistance (IR) in vitro. We investigated the effects of IRW on body composition, glucose homeostasis and insulin sensitivity in a high-fat diet (HFD) induced insulin resistant (IR) model. C57BL/6 mice were fed HFD for 6 weeks, after which IRW was incorporated into the diet (45 or 15 mg/kg body weight (BW)) until week 14. IRW45 (at a dose of 45 mg/kg BW) reduced BW (p = 0.0327), fat mass gain (p = 0.0085), and preserved lean mass of HFD mice (p = 0.0065), concomitant with enhanced glucose tolerance and reduced fasting glucose (p < 0.001). In skeletal muscle, IRW45 increased insulin-stimulated protein kinase B (AKT) phosphorylation (p = 0.0132) and glucose transporter 4 (GLUT4) translocation (p < 0.001). Angiotensin 2 receptor (AT2R) (p = 0.0024), phosphorylated 5′-AMP-activated protein kinase (AMPKα) (p < 0.0124) and peroxisome proliferator-activated receptor gamma (PPARγ) (p < 0.001) were enhanced in skeletal muscle of IRW45-treated mice, as was the expression of genes involved in myogenesis. Plasma angiotensin converting enzyme-2 (ACE2) activity was increased (p = 0.0016). Uncoupling protein-1 in white adipose tissue (WAT) was partially restored after IRW supplementation. IRW improves glucose tolerance and body composition in HFD-fed mice and promotes glucose uptake in skeletal muscle via multiple signaling pathways, independent of angiotensin converting enzyme (ACE) inhibition.

A comprehensive review on the glucoregulatory properties of food-derived bioactive peptides

Diabetes mellitus, a group of metabolic disorders characterized by persistent hyperglycemia, affects millions of people worldwide and is on the rise. Dietary proteins, from a wide range of food sources, are rich in bioactive peptides with antidiabetic properties. Notable examples include AGFAGDDAPR, a black tea-derived peptide, VRIRLLQRFNKRS, a β-conglycinin-derived peptide, and milk-derived peptide VPP, which have shown antidiabetic effects in diabetic rodent models through variety of pathways including improving beta-cells function, suppression of alpha-cells proliferation, inhibiting food intake, increasing portal cholecystokinin concentration, enhancing insulin signaling and glucose uptake, and ameliorating adipose tissue inflammation. Despite the immense research on glucoregulatory properties of bioactive peptides, incorporation of these bioactive peptides in functional foods or nutraceuticals is widely limited due to the existence of several challenges in the field of peptide research and commercialization. Ongoing research in this field, however, is fundamental to pave the road for this purpose.

Purification and characterization of hypoglycemic peptides from traditional Chinese soy-fermented douchi

Douchi is a popular soy-fermented food originated in China, with documented hypoglycemic effect. However, the responsible molecules and the mechanism underlying its beneficial effects remains unclear. Therefore, in this study,...

Bioactive peptides from foods: production, function, and application

Bioactive peptides are a class of peptides with special physiological functions and have potential applications in human health and disease prevention. Bioactive peptides have gained much research attention because they affect the cardiovascular, endocrine, immune, and nervous systems. Recent research has reported that bioactive peptides are of great value for physiological function regulation, including antioxidation, anti-hypertension, antithrombosis, antibacterial properties, anti-cancer, anti-inflammation, anti-diabetic, anti-obesity, cholesterol-lowering, immunoregulation, mineral binding and opioid activities. The production of food-derived bioactive peptides is mainly through the hydrolysis of digestive enzymes and proteolytic enzymes or microbial fermentation. The purpose of this review is to introduce the production, function, application, challenges, and prospects of food-derived bioactive peptides.

Bioactive Peptides and Hydrolysates from Egg Proteins as a New Tool for Protection Against Cardiovascular Problems

The aim of the present work is to review the potential beneficial effects of dietary supplementation with bioactive egg protein hydrolysates or peptides on cardiometabolic changes associated with oxidative stress. The development of nutritionally improved food products designed to address specific health concerns is of particular interest because many bioactive food compounds can be potentially useful in various physiological functions such as for reducing oxidative stress. The results presented suggest that egg hydrolysates or derived peptides could be included in the diet to prevent and/or reduce some cardiometabolic complications associated with oxidative stress-related diseases.

Bifunctional peptides with antioxidant and angiotensin-converting enzyme inhibitory activity in vitro from egg white hydrolysates

Oxidative stress is frequently associated with hypertension. However, the studies on antihypertensive peptides usually focus on ACE inhibitory activity and ignore antioxidant activity of bioactive peptides. In our research, we optimized enzymatic hydrolysis condition of egg white protein. After that we evaluated both the antioxidant and the ACE-inhibitory activity in vitro of egg white hydrolysates and its purified fractions. Four peptides, LAPYK, SVIRW, PKSVIRW, and ADWAK, which can match to ovotransferrin were identified from fraction with the highest bioactivity. Among them, LAPYK possessed the strongest activity with ABTS scavenging IC₅₀ of 5.29 ± 0.24 µM, ORAC of 1.50 ± 0.04 µM TE/µM, ACE-inhibitory IC₅₀ of 12.65 ± 1.34 µM. For further, we explored inhibitory mechanism of LAPYK against ACE. Research on bifunctional peptides is helpful for the application of antihypertensive peptides. PRACTICAL APPLICATIONS: At present, the therapeutic drugs for hypertension usually focus on a single target, but the pathogenesis of hypertension is multifactorial, and the combined treatment of multiple targets may have a better therapeutic effect. Compared with commercially available drugs, food-derived bioactive peptides have lower side effects, as well as exhibit multi-bioactivities more easily. Exploration of bifunctional peptides with both ACE inhibitory and antioxidant activity provides new ideas for the treatment of hypertension.

The sol-gel-sol transformation behavior of egg white proteins induced by alkali

In the current study, we found an interesting phenomenon that fresh egg white (EW) undergo the sol-gel-sol transition with alkali treatment. The transformation behavior at different alkalinity (1.5%, 2.0%, and 2.5%) was investigated. As the gel formed, the hardness, lightness, surface hydrophobicity and the total number of identified peptides increased, and then, remarkable reduction when the gel collapsed. Rheological behavior indicated that the viscosity varied with shear rate. Fourier transform infrared spectroscopy (FTIR) showed that β-sheets gradually decreased as the α-helices increased during gel-sol transformation. The quantification of EW peptides analysis revealed that there was no dramatic correlation between the number of identified peptides and alkalinity. It was concluded that the sol-gel-sol transition was strongly dependent on alkali levels, moreover, high concentration promoted gel formation as well as liquefaction. The EW transformation behavior induced by alkali had a significant effect on protein aggregation and denaturation, and further changed physicochemical properties.

Perspectives on the Potential Benefits of Antihypertensive Peptides towards Metabolic Syndrome

In addition to the regulation of blood pressure, the renin-angiotensin system (RAS) also plays a key role in the onset and development of insulin resistance, which is central to metabolic syndrome (MetS). Due to the interplay between RAS and insulin resistance, antihypertensive compounds may exert beneficial effects in the management of MetS. Food-derived bioactive peptides with RAS blocking properties can potentially improve adipose tissue dysfunction, glucose intolerance, and insulin resistance involved in the pathogenesis of MetS. This review discusses the pathophysiology of hypertension and the association between RAS and pathogenesis of the MetS. The effects of bioactive peptides with RAS modulating effects on other components of the MetS are discussed. While the in vivo reports on the effectiveness of antihypertensive peptides against MetS are encouraging, the exact mechanism by which these peptides infer their effects on glucose and lipid handling is mostly unknown. Therefore, careful design of experiments along with standardized physiological models to study the effect of antihypertensive peptides on insulin resistance and obesity could help to clarify this relationship.

A multi-approach peptidomic analysis of hen egg white reveals novel putative bioactive molecules

Chicken egg white is a raw material broadly used as additive for the preparation of food and cosmetoceutical products. To describe its molecular properties, various proteomic investigations were performed in the last decade characterizing highly abundant components. No peptidomic counterparts were accomplished so far; scientific literature only reports on the characterization of specific bioactive peptides or preparations from egg white and its hydrolysates, which was performed through dedicated functional assays. In this study, a broad description of the egg white peptidome at 24, 336 and 672 h after laying was achieved using three peptide extraction procedures, which were combined with MALDI-TOF-TOF-MS and nanoLC-ESI-Q-Orbitrap-MS/MS analyses. In the whole, 506 peptides were characterized; they mostly resulted from the physiological degradation of intact proteins following the activity of endoprotease ArgC-, trypsin- and plasmin-like enzymes. Eventual detection of peptide post-translational modifications also provided structural information on parental proteins. When analyzed by bioinformatics and/or compared with literature data, identified peptides allowed recognizing a number of protein fragments associated with different hypothetical biological activities. These results confirmed previous observations regarding functional characteristics of egg white unfractionated preparations or purified molecules, emphasizing the useful application of this raw material in human nutrition and cosmetics. Finally, a comparative label-free peptidomic evaluation of samples stored for different times under refrigeration identified 31 peptides showing significant quantitative changes during storage. BIOLOGICAL SIGNIFICANCE: This study provided the largest inventory of peptides described in chicken egg while so far. In addition, it identified a number of protein fragments associated with hypothetical antihypertensive, antioxidant, antiinflammatory, antimicrobial, anticancer, antiviral, antibiofilm, calcium-binding, antidiabetic, antithrombotic, adipogenic differentiating, stimulating/immunostimulating, hormonal, lipid-binding and cell adhesion-affecting activities. These results confirmed previous observations regarding functional characteristics of egg white unfractionated preparations or purified molecules, emphasizing the useful application of this raw material in human nutrition and cosmetics.

Novel ACE inhibitory tripeptides from ovotransferrin using bioinformatics and peptidomics approaches

Food-derived ACE inhibitory peptides have recently attracted increased attention. This work focused on a more efficient in silico method to find ACE inhibitory peptides from ovotransferrin. In this work, ovotransferrin was digested into peptides by virtual enzymolysis. Subsequently, in vitro ACE inhibitory activity of potential tripeptides was conducted following the peptide score, toxicity, and water solubility prediction. Both pharmacophore study and flexible docking were applied to analyze ACE inhibition mechanism of tripeptides. Our results demonstrated that EWL was a potent ACE inhibitory tripeptide with IC₅₀ value of 380 ± 10 μM. Besides, pharmacophore and flexible docking showed that the pi interaction and hydrogen bond were the key interactions in ACE-EWL complex. It appears that the in vitro ACE inhibitory activity of tripeptide EWL was consistent with its molecular modeling.

Separation and Identification of Highly Efficient Antioxidant Peptides from Eggshell Membrane

The enzymatic hydrolysates (EHs) of the eggshell membrane (ESM) were obtained after incubating eggshell membrane in solutions prepared with Na₂SO₃ and alkaline protease combinations. The effects of enzyme species, enzyme dosage, Na₂SO₃ concentration, and hydrolysis time on the antioxidant activity of the ESM-EH were determined. Also, the correlation between the degree of hydrolysis (DH) and the antioxidant activity of ESM-EH was analyzed. The DH of ESM-EH showed a highly positive correlation with the reducing power (R² = 0.857) and total antioxidant activity (TAA) (R² = 0.876) and performed negative correlation with the Fe²⁺-chelating ability (R² = −0.529). The molecular weight distribution of the ESM-EH was determined by MALDI-TOF/MS. Cation exchange chromatography (Sephadex C-25) was used to isolate the ESM-EH and then the enzymatic hydrolysis fragment (EHF) was obtained. Among the five isolated fragments (F1~F5), fragment 3 (F3), which was composed of 28 polypeptides, showed the highest ability to quench ABTS• (2,2-azinobis-3-ethyl-benzothiazoline-6-sulfonic acid) (90.44%) and also displayed stronger TBARS (thiobarbituric acid– reactive substances) (58.17%) and TAA (303.82 µg /mL) than the ESM-EH. Further analysis of the 28 peptides in F3 identified using LC-MS/MS indicated that five peptides (ESYHLPR, NVIDPPIYAR, MFAEWQPR, LLFAMTKPK, MLKMLPFK) showed high water-solubility, biological activities, and antioxidant characteristics. Finally, the TAA of the synthetic peptide was verified, the synthetic peptides ESYHLPR and MFAEWQPR performed the best activity and have high potentials to be used as antioxidant agents in functional foods, pharmaceuticals, or cosmetics.

Amino Acid Imprinted UiO-66s for Highly Recognized Adsorption of Small Angiotensin-Converting-Enzyme-Inhibitory Peptides

Introduction of targeted defects into microporous UiO-66s for manipulating their three-dimensional size and surface properties can endow them with adsorption and separation areas involving angiotensin-converting-enzyme-inhibitory (ACE-inhibitory) peptides. Three hydrophobic amino acids (AAs) (i.e., proline (Pro), phenylalanine (Phe), and tryptophan (Trp)) having different physical/chemical properties were applied to in situ tailor defects in UiO-66 through targeted incoordination of missing linkers or missing nodes. Characterization results revealed a uniform oval shape of the developed defects with lengths ranging from 1.8 to 3.1 nm, which was also highly consistent with our molecular simulation. Among these three defective UiO-66s, Phe and Trp imprinted UiO-66s significantly promoted the adsorption affinity of small ACE-inhibitory peptides (uptake: 1.25 mmol g^-1 for DDFF and 1.37 mmol g^-1 for DDWW) and ultrahigh selectivity for DDFF (249) or DDWW (279) from inactive KKKK solution based on a lock-and-key mechanism. As a result, the imprinted UiO-66 showed an enrichment capacity for ACE-inhibitory peptides about eight times higher than that of pristine UiO-66. Therefore, the amino acid imprinting strategy endorsed by its facile and discerning ability can be envisioned to be of great value for small functional peptide separation and oriented enrichment in biomedicines.

Egg white hydrolysate enhances insulin sensitivity in high-fat diet-induced insulin-resistant rats via Akt activation

Agents that block the renin-angiotensin system (RAS) improve glucoregulation in the metabolic syndrome disorder. We evaluated the effects of egg white hydrolysate (EWH), previously shown to modulate the protein abundance of RAS component in vivo, on glucose homeostasis in diet-induced insulin-resistant rats. Sprague-Dawley rats were fed a high-fat diet (HFD) for 6 weeks to induce insulin resistance. They were then randomly divided into four groups receiving HFD or HFD supplemented with different concentrations of EWH (1, 2 and 4 %) for another 6 weeks in the first trial. In the second trial, insulin-resistant rats were divided into two groups receiving only HFD or HFD+4 % EWH for 6 weeks. Glucose homeostasis was assessed by oral glucose tolerance and insulin tolerance tests. Insulin signalling and protein abundance of RAS components, gluconeogenesis enzymes and PPARγ were evaluated in muscle, fat and liver. Adipocyte morphology and inflammatory markers were evaluated. In vivo administration of EWH increased insulin sensitivity, improved oral glucose tolerance (P < 0·0001) and reduced systemic inflammation (P < 0·05). EWH potentiated insulin-induced Akt phosphorylation in muscle (P = 0·0341) and adipose tissue (P = 0·0276), but minimal differences in the protein abundance of tissue RAS components between the EWH and control groups were observed. EWH treatment also reduced adipocyte size (P = 0·0383) and increased PPARγ2 protein abundance (P = 0·0237). EWH treatment yielded positive effects on the inflammatory profile, glucose tolerance, insulin sensitivity and adipocyte differentiation in HFD-induced insulin resistance rats. The involvement of local RAS activity requires further investigation.

Bioactive Egg Proteins

The nutritional excellence of chicken egg is derived from its task as a life-giving medium, supplying the necessary nutrients to the hen's embryo while protecting it from external threats. Additionally, egg proteins possess unique biological activities above and beyond their known functional and nutritional roles. In the last few decades, extensive research has been done to evaluate the various biological activities of egg proteins and protein-derived peptides. Egg proteins and protein-derived peptides have been attributed to diverse biological activities, the most well-known being their antimicrobial properties. However, egg proteins and peptides have been shown to have other biological activities, such as antihypertensive, antioxidant, anticancer, immunomodulatory, and protease inhibitory activity. Egg-derived bioactive proteins have had a relevant scientific impact and exhibit promising applicability as an ingredient for the development of functional foods and nutraceuticals. However, it is critical to understand the effects of these proteins in signaling pathways to delineate their molecular mechanisms of action. Further studies are required to fill the current knowledge gaps. Therefore, the purpose of the chapter is to illustrate the present knowledge of the bioactivity of different egg proteins and their physiological effects.