Bioactive food derived peptides: a review on correlation between structure of bioactive peptides and their functional properties

Proteins in Food Systems-Bionanomaterials, Conventional and Unconventional Sources, Functional Properties, and Development Opportunities

Recently, food companies from various European countries have observed increased interest in high-protein food and other products with specific functional properties. This review article intends to present proteins as an increasingly popular ingredient in various food products that frequently draw contemporary consumers’ attention. The study describes the role of conventional, unconventional, and alternative sources of protein in the human body. Furthermore, the study explores proteins’ nutritional value and functional properties, their use in the food industry, and the application of proteins in bionanomaterials. Due to the expected increase in demand for high-protein products, the paper also examines the health benefits and risks of consuming these products, current market trends, and consumer preferences.

Rice bran-derived protein fractions enhance sulforaphane-induced anti-oxidative activity in gingival epithelial cells

OBJECTIVE

Food-derived bioactive peptides have been reported to exhibit various beneficial effects, including anti-microbial, anti-inflammatory, and anti-oxidant properties. Oxidative stress has been implicated in the development of several inflammatory diseases such as periodontal disease. However, the anti-oxidative effect of food-derived bioactive peptides in gingival epithelial cells (GECs) is unknown. Therefore, we examined the bioactivity of the peptides in GECs.

DESIGN

Food-derived peptide fractionations derived from rice bran, rice endosperm, corn, and soy were screened for anti-oxidative effects using anti-oxidant response element (ARE)-luciferase-transfected HEK 293 cells. The induction of anti-oxidation-related genes and proteins in GECs by the fractions were examined by quantitative PCR and Western blotting, respectively. Then, the fraction-mediated anti-oxidative effects were examined by measuring intracellular reactive oxygen species (ROS) levels using flow cytometry. Furthermore, the anti-oxidative response-related cellular signaling pathways were analyzed via Western blotting.

RESULTS

Although treatment with the food-derived peptides alone did not activate anti-oxidative responses, co-treatment with sulforaphane (SFN; a potent anti-oxidant) and certain food-derived peptides enhanced anti-oxidative responses in ARE-luciferase-transfected HEK 293 cells. The fractions augmented heme oxygenase-1 mRNA and protein expression in GECs. The percentage of ROS-positive cells was significantly decreased by co-treatment with SFN and peptide fractions derived from rice bran. Furthermore, the involvement of both nuclear factor erythroid 2-related factor 2 (Nrf2) and extracellular signal-regulated kinase (ERK) in the enhancement of anti-oxidative responses was demonstrated by Western blotting.

CONCLUSIONS

Peptides derived from rice bran enhances SFN-induced anti-oxidative responses in GECs through ERK-Nrf2-ARE signaling.

Chicken Feather Keratin Peptides for the Control of Keratinocyte Migration

FAO estimates that in 2030 the poultry meat production could reach 120 million tons, which is a challenge in terms of waste management. Feathers are mainly composed of keratin, an important biomaterial. Using feathers as a source of keratin will minimize the waste generated, while contributing to supply an important material for several industries, such as pharmaceutical and biomedical. The peptides were extracted from the feathers by microbial degradation. In this study, we evaluated the peptides effect on keratinocyte metabolic activity and migration. The influence of these peptides on non-activated and activated macrophages was also assessed. It was demonstrated that depending on the keratin peptide fraction in contact with keratinocytes, it is possible to modulate the migration rate of the keratinocytes. Peptide fraction with low molecular weight increases migration, while peptides with a high range of molecular sizes decreases it. Some peptide fractions induce the secretion of TNF-α in non-activated macrophages and not on activated macrophages, demonstrating that these peptides should only be placed in contact with cells, in the context of an ongoing inflammatory process. This work is a step forward on the understanding of keratin peptides influence on keratinocytes and immune cells system cells, macrophages.

Engineering Concanavalin B to Release Bioactive Peptides against Metabolic Syndrome

Metabolic syndrome is a severe public health issue characterized by multiple metabolic disturbances. Current treatments prescribe a particular drug for each of them, producing multiple side effects. As a first step towards a more integral approach, we applied our recently described methodology to design single proteins, based in the Concanavalin B scaffold (1CNV), that contain several bioactive peptides (BPs), including antioxidant and lipid-lowering activities as well as inhibitors of dipeptidyl peptidase IV (DPPIV) and the angiotensin converting enzyme. Modified Concanavalin (CNV44), the designed protein that showed the best in silico properties, was expressed in high yields in E. coli and purified to homogeneity. After in vitro digestion with gastrointestinal enzymes, all the biological activities tested where higher in CNV44 when compared to the non-modified protein 1CNV, or to other previous reports. The results presented here represent the first in vitro evidence of a modified protein with the potential to treat metabolic syndrome and open the venue for the design of proteins to treat other non-communicable diseases.

Plant Bioactive Peptides: Current Status and Prospects Towards Use on Human Health

Large numbers of bioactive peptides with potential applications in protecting against human diseases have been identified from plant sources. In this review, we summarized recent progress in the research of plant-derived bioactive peptides, encompassing their production, biological effects, and mechanisms. This review focuses on antioxidant, antimicrobial, antidiabetic, and anticancer peptides, giving special attention to evidence derived from cellular and animal models. Studies investigating peptides with known sequences and well-characterized peptidic fractions or protein hydrolysates will be discussed. The use of molecular docking tools to elucidate inter-molecular interactions between bioactive peptides and target proteins is highlighted. In conclusion, the accumulating evidence from in silico, in vitro and in vivo studies to date supports the envisioned applications of plant peptides as natural antioxidants as well as health-promoting agents. Notwithstanding, much work is still required before the envisioned applications of plant peptides can be realized. To this end, future researches for addressing current gaps were proposed.

Impact of Hydrolyzed Collagen from Defatted Sea Bass Skin on Proliferation and Differentiation of Preosteoblast MC3T3-E1 Cells

Osteoporosis is a serious problem affecting health of the elderly. Drugs (bisphosphonates) applied for treatment are often accompanied by adverse side effects. Thus, fish byproduct-derived peptides, particularly hydrolyzed collagen (HC) from defatted sea bass skin, could be a safe source of anti-osteoporosis agents. This study aimed to examine the effects of HC on proliferation and differentiation of preosteoblast cells. HC prepared using papain before Alcalase hydrolysis was determined for molecular weight (MW) distribution. Thereafter, the resulting HC (50-800 µg/mL) was added to the cell. Proliferation, alkaline phosphatase activity (AP-A) and mineralization of cells were investigated. Moreover, the expression of runt-related transcription factor 2 (RUNX2) and the p-Akt/Akt pathway were also determined using Western blot. The results showed that HC had an MW < 3 kDa. HC (50-200 µg/mL) could promote cell proliferation. Nevertheless, HC at 100 µg/mL (HC-100) had enhanced AP-A and increased mineralization during the first 7 days of culture. Moreover, HC-treated cells had higher calcium depositions than the control (p < 0.05). Additionally, cells treated with HC-100 had higher levels of RUNX2 and p-Akt expressions than control (p < 0.05). Therefore, HC could be a promising functional ingredient to promote osteoblast proliferation and differentiation, which could enhance bone strength.

Legumes as Functional Food for Cardiovascular Disease

Legumes are an essential food source worldwide. Their high-quality proteins, complex carbohydrates, dietary fiber, and relatively low-fat content make these an important functional food. Known to possess a multitude of health benefits, legume consumption is associated with the prevention and treatment of cardiovascular diseases (CVD). Legume crude protein isolates and purified peptides possess many cardiopreventive properties. Here, we review selected economically valued legumes, their taxonomy and distribution, biochemical composition, and their protein components and the mechanism(s) of action associated with cardiovascular health. Most of the legume protein studies had shown upregulation of low-density lipoprotein (LDL) receptor leading to increased binding and uptake, in effect significantly reducing total lipid levels in the blood serum and liver. This is followed by decreased biosynthesis of cholesterol and fatty acids. To understand the relationship of identified genes from legume studies, we performed gene network analysis, pathway, and gene ontology (GO) enrichment. Results showed that the genes were functionally interrelated while enrichment and pathway analysis revealed involvement in lipid transport, fatty acid and triglyceride metabolic processes, and regulatory processes. This review is the first attempt to collate all known mechanisms of action of legume proteins associated with cardiovascular health. This also provides a snapshot of possible targets leading to systems-level approaches to further investigate the cardiometabolic potentials of legumes.

Whether short peptides are good candidates for future neuroprotective therapeutics?

Neurodegenerative diseases are a broad group of largely debilitating, and ultimately terminal conditions resulting in progressive degeneration of different brain regions. The observed damages are associated with cell death, structural and functional deficits of neurons, or demyelination. The concept of neuroprotection concerns the administration of the agent, which should reverse some of the damage or prevent further adverse changes. A growing body of evidence suggested that among many classes of compounds considered as neuroprotective agents, peptides derived from natural materials or their synthetic analogs are good candidates. They presented a broad spectrum of activities and abilities to act through diverse mechanisms of action. Biologically active peptides have many properties, including antioxidant, antimicrobial, antiinflammatory, and immunomodulatory effects. Peptides with pro-survival and neuroprotective activities, associated with inhibition of oxidative stress, apoptosis, inflammation and are able to improve cell viability or mitochondrial functions, are also promising molecules of particular interest to the pharmaceutical industries. Peptide multiple activities open the way for broad application potential as therapeutic agents or ingredients of health-promoting functional foods. Significantly, synthetic peptides can be remodeled in numerous ways to have desired features, such as increased solubility or biological stability, as well as selectivity towards a specific receptor, and finally better membrane penetration. This review summarized the most common features of major neurodegenerative disorders, their causes, consequences, and reported new neuroprotective drug development approaches. The author focused on the unique perspectives in neuroprotection and provided a concise survey of short peptides proposed as novel therapeutic agents against various neurodegenerative diseases.

Effect of Fish Bone Bioactive Peptides on Oxidative, Inflammatory and Pigmentation Processes Triggered by UVB Irradiation in Skin Cells

In the present study, we evaluated for the first time the photoprotective effect of fish bone bioactive peptides (FBBP) preparation isolated from silver carp (Hypophthalmichthys molitrix) discarded tissue using in vitro experimental models of skin cells exposed to ultraviolet B (UVB) irradiation and stressing agents. FBBP preparation was obtained by papain treatment of minced bones and centrifugal ultrafiltration, and the molecular weight (MW) distribution was characterized by size exclusion and reversed-phase high performance liquid chromatography (RP-HPLC). In vitro assessment of the effect of FBBP pretreatment in UVB-irradiated L929 fibroblasts and HaCaT keratinocytes revealed their cytoprotective activity. Their capacity to efficiently reduce reactive oxygen species (ROS) production and lipid peroxidation varied in a dose-dependent manner, and it was greater in fibroblasts. A decrease of proinflammatory cytokines secretion, in particular of tumor necrosis factor alpha (TNF-α), was found after FBBP pretreatment of THP-1-derived inflamed macrophages. Melanin production and tyrosinase activity investigated in UVB-irradiated Mel-Juso cells were lowered in direct relation to FBBP concentrations. FBBP fractions with high radical scavenging activity were separated by ion exchange chromatography, and two collagenic sequences were identified. All these results offer new scientific data on aquaculture fish bone-derived peptides confirming their ability to control the antioxidant, anti-inflammatory and pigmentation processes developed during UV irradiation of skin cells and recommend their use as valuable natural ingredients of photoprotective cosmeceutical products.

A Review on Health-Promoting, Biological, and Functional Aspects of Bioactive Peptides in Food Applications

Food-derived bioactive peptides are being used as important functional ingredients for health-promoting foods and nutraceuticals in recent times in order to prevent and manage several diseases thanks to their biological activities. Bioactive peptides are specific protein fractions, which show broad applications in cosmetics, food additives, nutraceuticals, and pharmaceuticals as antimicrobial, antioxidant, antithrombotic, and angiotensin-I-converting enzyme (ACE)-inhibitory ingredients. These peptides can preserve consumer health by retarding chronic diseases owing to modulation or improvement of the physiological functions of human body. They can also affect functional characteristics of different foods such as dairy products, fermented beverages, and plant and marine proteins. This manuscript reviews different aspects of bioactive peptides concerning their biological (antihypertensive, antioxidative, antiobesity, and hypocholesterolemic) and functional (water holding capacity, solubility, emulsifying, and foaming) properties. Moreover, the properties of several bioactive peptides extracted from different foods as potential ingredients to formulate health promoting foods are described. Thus, multifunctional properties of bioactive peptides provide the possibility to formulate or develop novel healthy food products.

Exploring Molecular Insights of Cereal Peptidic Antioxidants in Metabolic Syndrome Prevention

The prevalence of metabolic syndrome (MetS) is presently an alarming public health problem globally. Oxidative stress has been postulated to be strongly correlated with MetS, such as type 2 diabetes, obesity, hypertension, cardiovascular diseases, and certain cancers. Cereals are important staple foods which account for a huge proportion of the human diet. However, owing to recent growing demand and the search for natural antioxidants for the prevention and management of MetS, cereal peptides have gained increasing attention for developing functional ingredients or foods with substantial antioxidant properties. This review explores the current production techniques for cereal peptidic antioxidants and their potential mechanism of action in the prevention and management of MetS.

Post translational modifications of milk proteins in geographically diverse goat breeds

Goat milk is a source of nutrition in difficult areas and has lesser allerginicity than cow milk. It is leading in the area for nutraceutical formulation and drug development using goat mammary gland as a bioreactor. Post translational modifications of a protein regulate protein function, biological activity, stabilization and interactions. The protein variants of goat milk from 10 breeds were studied for the post translational modifications by combining highly sensitive 2DE and Q-Exactive LC-MS/MS. Here we observed high levels of post translational modifications in 201 peptides of 120 goat milk proteins. The phosphosites observed for CSN2, CSN1S1, CSN1S2, CSN3 were 11P, 13P, 17P and 6P, respectively in 105 casein phosphopeptides. Whey proteins BLG and LALBA showed 19 and 4 phosphosites respectively. Post translational modification was observed in 45 low abundant non-casein milk proteins mainly associated with signal transduction, immune system, developmental biology and metabolism pathways. P_asp is reported for the first time in 47 sites. The rare conserved peptide sequence of (SSSEE) was observed in αS1 and αS2 casein. The functional roles of identified phosphopeptides included anti-microbial, DPP-IV inhibitory, anti-inflammatory and ACE inhibitory. This is first report from tropics, investigating post translational modifications in casein and non-casein goat milk proteins and studies their interactions.

Health Benefits of Antioxidative Peptides Derived from Legume Proteins with a High Amino Acid Score

Legumes such as soybean, chickpea, lentil, cowpea, and mung bean, are valuable sources of protein with a high amino acid score and can provide bioactive peptides. This manuscript presents a review on legume-derived peptides, focusing on in vitro and in vivo studies on the potential antioxidative activities of protein hydrolysates and their characterization, amino acid sequences, or purified/novel peptides. The health implications of legume-derived antioxidative peptides in reducing the risks of cancer and cardiovascular diseases are linked with their potent action against oxidation and inflammation. The molecular weight profiles and amino acid sequences of purified and characterized legume-derived antioxidant peptides are not well established. Therefore, further exploration of legume protein hydrolysates is necessary for assessing the potential applications of antioxidant-derived peptides in the functional food industry.

In situ monitoring of grape seed protein hydrolysis by Raman spectroscopy

Raman spectroscopy was used to monitor the enzymatic hydrolysis process of grape seed protein. The degree of hydrolysis (DH), IC₅₀ of the ACE inhibitory activity, and peptide content of the digestive products of grape seed protein were analyzed offline. The partial least squares (PLS), interval partial least squares (IPLS), and joint interval partial least squares (Si-PLS) models of DH, IC₅₀ , and peptide content were established and the optimal pretreatment method was selected. In the optimal model, the corrected model r of the grape seed protein hydrolysis degree is 0.997, the Root Mean Square Error of Cross Validation (RMSECV) is 0.507%. The predicted model r value is 0.9932, the Root Mean Square Error of Prediction (RMSEP) is 1.15%. The corrected model r value of the IC₅₀ is 0.9965, the RMSECV is 11.9%. The r value and RMSEP of predicted model are 0.9978 and 9.64%. The corrected model r value of the peptide content is 0.9955, the RMSECV is 12.7%, the predicted model r value is 0.9953, and the RMSEP is 15.4%. These results showed that in situ real-time monitoring of grape seed protein hydrolysis process can be achieved by Raman spectroscopy. PRACTICAL APPLICATIONS: This study uses Raman spectroscopy method to establish the quantification of proteolysis, IC50, and peptide content of the simulated digestive products during grape seed proteolysis. Analyze the model to monitor and evaluate the target parameters during the entire grape seed proteolysis process. In situ real-time monitoring of grape seed proteolysis is of great significance to the entire grape seed active peptide industry.

Effect of hydrolyzed collagen from defatted Asian sea bass (Lates calcarifer) skin on fibroblast proliferation, migration and antioxidant activities

Hydrolyzed collagen from the defatted Asian sea bass (Lates calcarifer) (Asbs-HC) had high hydrophobic amino acids and imino acids. When fibroblast cell was treated with Asbs-HC, there was no cytotoxicity at any concentrations (25-1000 µg/mL). Asbs-HC at 1000 µg/mL exhibited the highest cell proliferation and cell migration (p < 0.05), indicating wound healing ability. Antioxidative activities of Asbs-HC at different concentrations were determined. ABTS radical scavenging activity (ABTS-RSA) and oxygen radical absorbance capacity (ORAC) increased when Asbs-HC levels augmented up to 1 mg/mL (p < 0.05). Decreased activities in scavenging DPPH radical and chelating metal were found at higher levels of Asbs-HC (0.5 and 1 mg/mL) (p < 0.05). Molecular weight (MW) of peptides in Asbs-HC ranged from 406 to 16,120 Da. Peptide containing MW of 406 Da rendered the highest scavenging activity towards ABTS radical. Thus, Asbs-HC could be applied as antioxidant, skin nourishment and wound healing agents for food/drink fortification.

Functional and Bioactive Properties of Peptides Derived from Marine Side Streams

In fish processing, a great amount of side streams, including skin, bones, heads and viscera, is wasted or downgraded as feed on a daily basis. These side streams are rich sources of bioactive nitrogenous compounds and protein, which can be converted into peptides through enzymatic hydrolysis as well as bacterial fermentation. Peptides are short or long chains of amino acids differing in structure and molecular weight. They can be considered as biologically active as they can contribute to physiological functions in organisms with applications in the food and pharmaceutical industries. In the food industry, such bioactive peptides can be used as preservatives or antioxidants to prevent food spoilage. Furthermore, peptides contain several functional qualities that can be exploited as tools in modifying food ingredient solubility, water-holding and fat-binding capacity and gel formation. In the pharmaceutical industry, peptides can be used as antioxidants, but also as antihypertensive, anticoagulant and immunomodulatory compounds, amongst other functions. On the basis of their properties, peptides can thus be used in the development of functional foods and nutraceuticals. This review focuses on the bioactive peptides derived from seafood side streams and discusses their technological properties, biological activities and applications.

Covalent Immobilization of Proteases on Polylactic Acid for Proteins Hydrolysis and Waste Biomass Protein Content Valorization

The recovery of the protein component and its transformation into protein hydrolysates, generally carried out chemically, gives great added value to waste biomasses. The production of protein hydrolysates through enzymatic catalysis would guarantee to lower the environmental impact of the process and raise product quality, due to the reproducible formation of low molecular weight peptides, with interesting and often unexplored biological activities. The immobilization of the enzymes represents a good choice in terms of stability, recyclability and reduction of costs. In this context, we covalently linked proteases from Aspergillus oryzae to polylactic acid an eco-friendly biopolymer. The hydrolytic efficiency of immobilized enzymes was assessed testing their stability to temperature and over time, and checking the hydrolysis of model biomasses (casein and bovine serum albumin). Soybean waste extracts were also used as proof of principle.

Translating bioactive peptides for COVID-19 therapy

COVID-19 (Coronavirus disease 2019) is a global pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a positive-sense RNA virus. This virus has emerged as a threat to global health, social stability, and the global economy. This pandemic continues to cause rampant mortality worldwide with the dire urgency to develop novel therapeutic agents. To meet this task, this article discusses advances in the research and potential application of bioactive peptides for possible mitigation of infection by SARS-CoV-2. Growing insight into the molecular biology of SARS-CoV-2 has revealed potential druggable targets for bioactive peptides. Bioactive peptides with unique amino acid sequences can mitigate such targets including, type II transmembrane serine proteases (TMPRSS2) inhibition, furin cleavage, and renin-angiotensin-aldosterone system (RAAS) members. Based on current evidence and structure-function analysis, multiple bioactive peptides present potency to neutralize the virus. To date, no SARS-CoV-2-explicit drug has been reported, but we here introduce bioactive peptides in the perspective of their potential activity against SARS-CoV-2 infection.

In vitro antioxidant and antihypertensive properties of sesame seed enzymatic protein hydrolysate and ultrafiltration peptide fractions

The objective of this study was to determine the in vitro antioxidant and antihypertensive potentials of sesame seed protein hydrolysate and its membrane ultrafiltration peptide fractions in comparison to the unhydrolyzed protein. Sesame seed protein isolate (SESPI) was prepared from the defatted sesame seed meal and then hydrolyzed using consecutive additions of pepsin and pancreatin to yield sesame protein hydrolysate (SESPH). The SESPH was subjected to membrane ultrafiltration consecutively to obtain fractions with peptide sizes of <1, 1-3, 3-5, and 5-10 kDa, respectively, which were then assayed for in vitro antioxidant and antihypertensive properties. The results showed that protein hydrolysis and fractionation led to significant (p < .05) increases in the content of hydrophobic amino acids. Radical scavenging and metal ion chelation were also significantly (p < .05) enhanced by these treatments. Inhibition of linoleic acid oxidation was stronger with the 1.0 mg/ml of sesame peptide samples in comparison to the mild inhibitory effect exhibited by the 0.5 mg/ml of samples. The <1 kDa peptide fraction was the most active inhibitor (81%) against angiotensin converting enzyme, whereas the bigger peptides (>3-5 and 5-10 kDa) were the most effective (75%-85% ) inhibitors against renin. These sesame products could be used as therapeutic agents in the development of health enhancing foods for the prevention and management of chronic diseases. PRACTICAL APPLICATIONS: Bioactive peptides have been produced from plant protein sources through in vitro enzymatic activities. Sesame seed peptides have demonstrated multifunctional potential to act as antioxidative and antihypertensive agents that could be utilized as ingredients for the development of novel functional foods and nutraceuticals.

Prospects of cereal protein-derived bioactive peptides: Sources, bioactivities diversity, and production

Cereals account for a large proportion of the human diet and are an important source of protein. The preparation of cereal protein peptides is a good way to utilize these proteins. Cereal protein peptides have good application potential as antioxidant, antibacterial, anti-inflammatory and anticancer compounds, in lowering blood pressure, controlling blood sugar, and inhibiting thrombosis. This article reviews the literature on the functional properties, mechanisms of action, and applications of cereal protein peptides in the food industry with two perspectives, and summarizes the methods for their preparation and identification. The biologically active peptides derived from different grain proteins have varied main functional properties, which may be related to the differences in the amino acid composition and protein types of different grains. On this basis, the structure-activity relationship of cereal protein peptides was discussed. The advancement of identification technology makes the integration of bioinformatics and bioactive peptide research closer. Bioinformatics by combination of online database, computer simulation and experimental verification is helpful to in-deep study the structure-activity relationship of biologically active peptides, and improve efficiency in the process of obtaining target peptides with less cost. In addition, the application of cereal protein peptides in the food industry is also discussed.

Fatty Acid Profile and Antioxidative Properties of Peptides Isolated from Fermented Lamb Loin Treated with Fermented Milk

This study evaluated the impact of fermented milk maceration on fermented lamb loin without nitrate to obtain peptides with high activity against oxidative changes (ABTS, DPPH, reducing power) as well as a favorable fatty acid profile, including CLA content. Additionally, an attempt was made to evaluate the influence of the lamb breed on the assessed properties. Raw loins (m. Longissimus dorsi) obtained from sheep of three polish breeds—Wrzosówka, Uhruska, and Świniarka—and fermented products were tested. The fermented loins obtained after 14 days of processing were characterized by pH and water activity values in the ranges, respectively, 4.76–5.12 and 0.902–0.915. The maceration of meat in a fermented milk has caused greater acidification of the meat during fermentation. Statistical analysis indicated that treatment was the factor with significant effect on peptide content; no effect of animal breed was found. The peptide content isolated from raw meat ranged from 2.90 to 4.31 mg g⁻¹ of sample, while in fermented meat products it was significant higher (11.59–16.37 mg g⁻¹ of product). The antioxidant properties of peptides were positively correlated with peptides content. The maceration in fermented milk resulted in a statistically significant increase of ABTS value in case of fermented lamb loin of Świniarka breed. The raw meat and fermented meat products form the Świniarka lamb breed were characterized by the highest content of the total CLA isomers. The main CLA isomer found was cis9-trans11 (rumenic acid), followed by cis9-cis11, trans9-trans11, and trans10-cis12. The rumenic acid content was higher than, respectively, 87% and 80–88% of total CLA isomers in case of raw meat and fermented lamb loins of three breeds.

Bioactive peptides derived from plant origin by-products: Biological activities and techno-functional utilizations in food developments - A review

Agro-industrial by-products containing considerable amounts of protein (10-50%) such as soybean meal, rice bran and coconut pulp are promising bioactive peptide sources with annual disposal rate of 800 million tons in the world. More recently, plant by-products rich in protein content have been studied under various prisms that include recovery techniques, peptide production methods, determination of technological benefits and functional properties, and their applications in foods. The researches in bioactive peptides provide evidence over the techno-functional properties and the health benefits are highly dependent upon their amino acid sequences, molecular weights, conformations and surface properties. Research findings compared bioactive properties of the obtained peptides with respect to their amino acid sequences and also reported that hydrophobic/hydrophilic properties have direct effect on both functional and health effects. In addition, the resultant properties of the peptides could be affected by the conducted extraction method (alkaline, enzymatic, ultrasound assisted, microwave assisted, etc.), extraction solvent, precipitation and purification techniques and even by the final drying process (spray, freeze, vacuum, etc.) which may alter molecular weights, conformations and surface properties. Latest studies have investigated solubility, emulsifying, foaming, water/oil holding capacity and surface properties and also antioxidant, antimicrobial, anticarcinogenic, hypocholesterolemic, antihypertensive, immunomodulatory and opioid activities of bioactive peptides obtained from plant by-products. Moreover, the application of the bioactive peptides into different food formulations has been a recent trend of functional food development. These bioactive peptides' bitter taste and toxicity are possible challenges in some cases that need to be resolved before their wider utilization.

Characterisation of Seasonal Mytilus edulis By-Products and Generation of Bioactive Hydrolysates

Mussel cultivation results in tons of by-product, with 27% of the harvest considered as reject material. In this study, mussel by-products considered to be undersized (mussels with a cooked meat yield <30%), mussels with broken shells and barnacle-fouled mussels were collected from three different locations in the west, north-west and south-west of Ireland. Samples were hydrolysed using controlled temperatures and agitation, and the proteolytic enzyme Protamex® was added at an enzyme:substrate ratio of 1:50 (w:v). The hydrolysates were freeze-dried and analysed for protein content and amino acid composition, lipid content and fatty acid methyl ester (FAME) composition, ash and techno-functional and bioactive activities. The degree of hydrolysis was determined using the Adler-Nissen pH stat method and was found to be between 2.41% ± 0% and 7.55% ± 0.6%. Mussel by-products harvested between February and May 2019 had protein contents ranging from 36.76% ± 0.41% to 52.19% ± 1.78%. The protein content of mussels collected from July to October (the spawning season) ranged from 59.07% ± 1.375% to 68.31% ± 3.42%. The ratio of essential to nonessential amino acids varied from 0.68–0.96 and it was highest for a sample collected in November from the west of Ireland. All the hydrolysate samples contained omega-3 polyunsaturated fatty acids (PUFA), especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are known anti-inflammatory agents. Selected hydrolysates which had angiotensin-converting enzyme I (ACE-I; EC 3.4.15.1) and dipeptidyl peptidase IV (DPP-IV; EC 3.4.14.5) inhibitory activities were filtered using 3-kDa membrane filtration and the permeate fraction was sequenced using mass spectrometry (MS). Identified peptides were >7 amino acids in length. Following BIOPEP database mining, 91% of the by-product mussel peptides identified were found to be previously identified DPP-IV and ACE-I inhibitory peptides, and this was confirmed using in vitro bioassays. The ACE-I inhibitory activity of the by-product mussel hydrolysates ranged from 22.23% ± 1.79% to 86.08% ± 1.59% and the most active hydrolysate had an ACE-I inhibitory concentration (IC50) value of 0.2944 mg/mL compared to the positive control, captopril. This work demonstrates that by-product mussel hydrolysates have potential for use as health-promoting ingredients.

Reduction of Oxidative Stress through Activating the Nrf2 mediated HO-1 Antioxidant Efficacy Signaling Pathway by MS15, an Antimicrobial Peptide from Bacillus velezensis

The efficient culture and purification of antimicrobial peptides (AMPs), along with intense antioxidant activity, have drawn the interest to study antioxidant activity mechanism. We report the culture conditions optimization, efficient biosynthesis, and purification of an antioxidant peptide MS15 from Bacillus velezensis obtained from fermented food that would generate heme oxygenase-1 (HO-1) expression and lead to nuclear factor erythroid 2-related factor-2 (Nrf2) nuclear translocation. We explored the ability of kinetics and potency for the bacterial killing to work against various pathogenic bacteria. A bioassay showed the lysis zone of MS15 by tricine SDS-PAGE near at 6 kDa. MALDI-TOF/MS verified molecular weight, and the existence of a molecular mass of 6091 Da was reported by purity. The MIC of MS15 ranged from 2.5-160 μg/mL for many pathogenic bacteria, showing greater potency. In macrophage RAW 264.7 cells, MS15 was exposed to assess its inhibitory effect against the generation of reactive oxygen species (ROS) in oxidative stress. In the sample treated group, the translation, and transcriptional levels of CAT (catalase), GPx (glutathione peroxidase), and SOD (superoxide dismutase) were significantly greater. In short, MS15 has significant antioxidant properties, reducing ROS production in RAW 264.7 cells, and raising the translation and transcriptional rates of antioxidant enzymes with stimulating HO-1 induction facilitated by Nrf2.

Insights on Health and Food Applications of Equus asinus (Donkey) Milk Bioactive Proteins and Peptides-An Overview

Due to its similarity with human milk and its low allergenic properties, donkey milk has long been used as an alternative for infants and patients with cow's milk protein allergy (CMPA). In addition, this milk is attracting growing interest in human nutrition because of presumed health benefits. It has antioxidant, antimicrobial, antitumoral, antiproliferative and antidiabetic activity. In addition, it stimulates the immune system, regulates the gastrointestinal flora, and prevents inflammatory diseases. Although all donkey milk components can contribute to functional and nutritional effects, it is generally accepted that the whey protein fraction plays a significant role. This review aims to highlight the active proteins and peptides of donkey milk in comparison with other types of milk, emphasizing their properties and their roles in different fields of health and food applications.

Identification and Antimicrobial Activity of Medium-Sized and Short Peptides from Yellowfin Tuna (Thunnus albacares) Simulated Gastrointestinal Digestion

Due to the rapidly increasing resistance to conventional antibiotics, antimicrobial peptides are emerging as promising novel drug candidates. In this study, peptide fragments were obtained from yellowfin tuna muscle by simulated gastrointestinal digestion, and their antimicrobial activity towards Gram-positive and Gram-negative bacteria was investigated. In particular, the antimicrobial activity of both medium- and short-sized peptides was investigated by using two dedicated approaches. Medium-sized peptides were purified by solid phase extraction on C18, while short peptides were purified thanks to a graphitized carbon black sorbent. For medium-sized peptide characterization, a peptidomic strategy based on shotgun proteomics analysis was employed, and identification was achieved by matching protein sequence database by homology, as yellowfin tuna is a non-model organism, leading to the identification of 403 peptides. As for short peptide sequences, an untargeted suspect screening approach was carried out by means of an inclusion list presenting the exact mass to charge ratios (m/z) values for all di-, tri- and tetrapeptides. In total, 572 short sequences were identified thanks to a customized workflow dedicated to short peptide analysis implemented on Compound Discoverer software.

Fermented milk: The most popular probiotic food carrier

Fermented milks are extensively produced and consumed all around the world. The production of these products is an old process that was used for extending the shelf life of milk. Nowadays, numerous traditional and industrial fermented milks with various texture and aroma can be found as an important part of human diet that exhibit several health benefits. In recent years, consumers' awareness about the effect of diet on health and tendency for consuming healthful food products directed manufacturers to develop functional foods. In this context, production of probiotic food products is a common approach. Fermented milks are suitable carrier for probiotics and their production and consumption can be a beneficial way for improving health status. For development of probiotic fermented milks, probiotic viability during fermentation and storage time, their interaction with starter cultures in the product as well as their effect on sensory properties of the product should be taken into account. This chapter describes different fermented milks, probiotics used in fermented milks, process of their production and quality aspects associated with these products.

Bioactive Peptides and Dietary Polyphenols: Two Sides of the Same Coin

The call for health-promoting nutraceuticals and functional foods containing bioactive compounds is growing. Among the great diversity of functional phytochemicals, polyphenols and, more recently, bioactive peptides have stood out as functional compounds. The amount of an ingested nutrient able to reach the bloodstream and exert the biological activity is a critical factor, and is affected by several factors, such as food components and food processing. This can lead to unclaimed interactions and/or reactions between bioactive compounds, which is particularly important for these bioactive compounds, since some polyphenols are widely known for their ability to interact and/or precipitate proteins/peptides. This review focuses on this important topic, addressing how these interactions could affect molecules digestion, absorption, metabolism and (biological)function. At the end, it is evidenced that further research is needed to understand the true effect of polyphenol-bioactive peptide interactions on overall health outcomes.

Extraction and Characterization of Antioxidant Peptides from Fruit Residues

Fruit residues with high protein contents are generated during the processing of some fruits. These sustainable sources of proteins are usually discarded and, in all cases, underused. In addition to proteins, these residues can also be sources of peptides with protective effects against oxidative damage. The revalorization of these residues, as sources of antioxidant peptides, requires the development of suitable methodologies for their extraction and the application of analytical techniques for their characterization. The exploitation of these residues involves two main steps: the extraction and purification of proteins and their hydrolysis to release peptides. The extraction of proteins is mainly carried out under alkaline conditions and, in some cases, denaturing reagents are also employed to improve protein solubilization. Alternatively, more sustainable strategies based on the use of high-intensity focused ultrasounds, microwaves, pressurized liquids, electric fields, or discharges, as well as deep eutectic solvents, are being implemented for the extraction of proteins. The scarce selectivity of these extraction methods usually makes the subsequent purification of proteins necessary. The purification of proteins based on their precipitation or the use of ultrafiltration has been the usual procedure, but new strategies based on nanomaterials are also being explored. The release of potential antioxidant peptides from proteins is the next step. Microbial fermentation and, especially, digestion with enzymes such as Alcalase, thermolysin, or flavourzyme have been the most common. Released peptides are next characterized by the evaluation of their antioxidant properties and the application of proteomic tools to identify their sequences.

Microbial Fermentation of Industrial Rice-Starch Byproduct as Valuable Source of Peptide Fractions with Health-Related Activity

The rice-starch processing industry produces large amounts of a protein-rich byproducts during the conversion of broken rice to powder and crystal starch. Given the poor protein solubility, this material is currently discarded or used as animal feed. To fully exploit rice's nutritional properties and reduce this waste, a biotechnological approach was adopted, inducing fermentation with selected microorganisms capable of converting the substrate into peptide fractions with health-related bioactivity. Lactic acid bacteria were preferred to other microorganisms for their safety, efficient proteolytic system, and adaptability to different environments. Peptide fractions with different molecular weight ranges were recovered from the fermented substrate by means of cross-flow membrane filtration. The fractions displayed in vitro antioxidant, antihypertensive, and anti-tyrosinase activities as well as cell-based anti-inflammatory and anti-aging effects. In the future, the peptide fractions isolated from this rice byproduct could be directly exploited as health-promoting functional foods, dietary supplements, and pharmaceutical preparations. The suggested biotechnological process harnessing microbial bioconversion may represent a potential solution for many different protein-containing substrates currently treated as byproducts (or worse, waste) by the food industry.

Identification and characterization of antioxidant peptides from Chinese dry-cured mutton ham

BACKGROUND

Chinese mutton ham is a dry-cured meat product with a long ripening time. The aim of this study was to identify and characterize antioxidant peptides from Chinese mutton ham.

RESULTS

Mutton ham peptides (MHPs) were purified by gel filtration, anion exchange and reversed-phase high-performance liquid chromatography steps. The 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) free radical scavenging capacity was used to guide the purification of MHPs. Three antioxidant peptides were identified by liquid chromatography with tandem mass spectrometry (LC-MS/MS) as Met-Trp-Thr-Asp (MWTD), Ala-Pro-Tyr-Met-Met (APYMM) and Phe-Trp-Ile-Ile-Glu (FWIIE), with molecular weights 551.61, 611.76, and 706.84 Da, respectively. Among them, APYMM exhibited the highest ABTS radical scavenging activity. The three peptides had the ability to inhibit lipid oxidation and Fenton's reagent-induced protein oxidation and DNA damage. After simulated gastrointestinal digestion, FWIIE and APYMM showed increased antioxidant activity, while MWTD showed decreased activity.

CONCLUSION

Three novel peptides isolated from Chinese mutton ham had strong biological activity. Chinese mutton ham is potentially a functional food and an excellent source of natural antioxidants. © 2019 Society of Chemical Industry.

Identification of New Peptides from Fermented Milk Showing Antioxidant Properties: Mechanism of Action

Due to their beneficial properties, fermented foods are considered important constituents of the human diet. They also contain bioactive peptides, health-promoting compounds studied for a wide range of effects. In this work, several antioxidant peptides extracted from fermented milk proteins were investigated. First, enriched peptide fractions were purified and analysed for their antioxidant capacity in vitro and in a cellular model. Subsequently, from the most active fractions, 23 peptides were identified by mass spectrometry MS/MS), synthesized and tested. Peptides N-15-M, E-11-F, Q-14-R and A-17-E were selected for their antioxidant effects on Caco-2 cells both in the protection against oxidative stress and inhibition of ROS production. To define their action mechanism, the activation of the Kelch-like ECH-associated protein 1/nuclear factor erythroid 2-related factor 2(Keap1/Nrf2) pathway was studied evaluating the translocation of Nrf2 from cytosol to nucleus. In cells treated with N-15-M, Q-14-R and A-17-E, a higher amount of Nrf2 was found in the nucleus with respect to the control. In addition, the three active peptides, through the activation of Keap1/Nrf2 pathway, led to overexpression and increased activity of antioxidant enzymes. Molecular docking analysis confirmed the potential ability of N-15-M, Q-14-R and A-17-E to bind Keap1, showing their destabilizing effect on Keap1/Nrf2 interaction.

Peptides obtained from edible mushrooms: Hericium erinaceus offers the ability to scavenge free radicals and induce apoptosis in lung cancer cells in humans

This research examined the antioxidant abilities of peptides derived from the Hericium erinaceus mushroom produced via three microbial proteases at varying concentrations.