Antioxidative peptides derived from plants for human nutrition: their production, mechanisms and applications

Plant-based antioxidant peptides: impact on oxidative stress and gut microbiota

Plant-based peptides can be obtained from natural and climate-friendly sources. These peptides show various bioactivities including antioxidant activity. Oxidative stress has an impact on the gut microbiota causing inflammation, insulin resistance, osteoporosis, cancer, and several chronic diseases like type 2 diabetes, arthritis, hypertension, and atherosclerosis. Therefore, antioxidant peptides may significantly affect oxidative stress as a potential alternative to conventional medication. The production of antioxidant peptides from plant-based protein sources through conventional and innovative approaches may provide promising strategies to improve gut microbiota. Recent studies in plant-based antioxidant peptides (PBAP) focus on their advanced identification and characterization techniques, structure-activity relationship, improvement of extraction and purification, cellular and molecular mechanisms, specific health applications in preventing and managing conditions with gut microbiota, and commercial applications in nutraceuticals. Short-chain fatty acids and reactive sulfur species are specific gut-derived metabolites that can improve metabolic function by modulating oxidative stress and the immune system. This review highlights the influence of food oxidants on the gut microbiota and PBAP-induced modulation of gut microbiota. Moreover, the production of PBAP and the challenges in their application will be discussed.

Antioxidant potential of peptides derived from chia seeds (Salvia hispanica L.) as natural preservatives

The challenge of preserving food quality without relying on harmful antioxidants requires the exploration of natural alternatives, such as chia-derived peptides (YACLKVK, KLKKNL, KLLKKYL, and KKLLKI). The antioxidant properties and stability to processing were evaluated using DPPH and ABTS, iron-reducing, ORAC, and copper chelating assays. The effects of autoclaving, heat treatment with glucose, and ultrasound on the antioxidant activity of the top-performing peptide were examined. YACLKVK displayed the highest antioxidant response with 87.25 ± 2.47 %, 93.65 ± 0.79 %, 0.418 ± 0.018 abs, 44.06 ± 0.78 μM TE/mL, and 86.49 ± 0.12 % in the DPPH, ABTS, iron-reducing capacity, ORAC, and copper chelating assays at 800 μg/mL (DPPH) and 1000 μg/mL, respectively. Autoclaving, heat, and ultrasound treatments reduced YACLKVK's DPPH scavenging to 63.09 ± 0.44 % and 74.15 ± 0.27 % and its Cu chelating capacity to 58.98 ± 1.28 %. YACLKVK retained over 50 % of its antioxidant capacity post-processing. These findings suggest its application as a potent natural antioxidant in food systems, particularly in processed foods where oxidation affects shelf life and quality. Incorporating YACLKVK could enhance food preservation, aligning with consumer preferences for natural-origin ingredients. Studies on commercial scalability, safety, and regulatory compliance will be essential for its widespread adoption in the food industry.

Exploration of antioxidant peptides from crocodile (Crocodylus siamensis) meat using modern information technology: Virtual-screening and antioxidant mechanisms

To develop a safe, stable and easily absorbed new antioxidant peptide. The myofibrillar protein hydrolysates of Siamese crocodile meat were prepared and purified, their free radical scavenging and Fe2+ chelating ability were determined. The results showed that isolated component 3 of neutral protease hydrolysate (N3) had the highest antioxidant activity. Subsequently, liquid chromatography-mass spectrometry was applied to appraise the amino acid sequences within the N3 component, and 8 novel antioxidant peptides were screened by bioinformatics analysis, the antioxidant test proved that all 8 synthetic peptides had certain antioxidant activity. Among them, there was no significant difference in the DPPH radical scavenging capacity of GWDK, LWDK, ERWP, LGWK and LWAK (P > 0.05), which were higher than that of DFRDY and WYRDD (P < 0.05), the ABTS radical scavenging ability of DFRDY was similar to WYRDD (P > 0.05), but remarkably stronger than that of the other 6 peptides (P < 0.05). Finally, the binding mechanism of 8 novel peptides to Keap1 protein was explored through molecular docking, and it was found that hydrogen bonding and hydrophobic interaction were the primary forces that bind antioxidant peptides to Keap1 protein.

Antioxidative and mineral-binding food-derived peptides: Production, functions, metal complexation conditions, and digestive fate

The discovery of food-derived biopeptides is becoming increasingly prevalent in the scientific community. Some peptides possess multiple biological functions that can confer health benefits through various mechanisms following ingestion. The present review targets food-derived antioxidant and mineral-binding peptides (AMBPs) including their production procedure i.e., enzymolysis, separation, and purification (through membrane separation, gel filtration, ion exchange chromatography, and high-performance liquid chromatography), followed by mass spectrometry for identification. The most effective AMBPs exhibit radical scavenging activity, detoxification of excess metals, and reduction of lipid peroxidation to facilitate mineral bioavailability. The metal complexation of AMBPs necessitates an optimal metal-to-peptide ratio, specific ligands, precursors, and complexation reactions. The bioavailability and absorbability mechanisms of AMBPs are also elucidated, encompassing gastrointestinal stability, binding mode, and cell absorption machinery. Ultimately, further considerations regarding additional research on AMBPs are provided, which will assist researchers in conducting more comprehensive studies to promote the effective and safe use of AMBPs.

Aggregation Rules of Short Peptides

The elucidation of aggregation rules for short peptides (e.g., tetrapeptides and pentapeptides) is crucial for the precise manipulation of aggregation. In this study, we derive comprehensive aggregation rules for tetrapeptides and pentapeptides across the entire sequence space based on the aggregation propensity values predicted by a transformer-based deep learning model. Our analysis focuses on three quantitative aspects. First, we investigate the type and positional effects of amino acids on aggregation, considering both the first- and second-order contributions. By identifying specific amino acids and amino acid pairs that promote or attenuate aggregation, we gain insights into the underlying aggregation mechanisms. Second, we explore the transferability of aggregation propensities between tetrapeptides and pentapeptides, aiming to explore the possibility of enhancing or mitigating aggregation by concatenating or removing specific amino acids at the termini. Finally, we evaluate the aggregation morphologies of over 20,000 tetrapeptides, regarding the morphology distribution and type and positional contributions of each amino acid. This work extends the existing aggregation rules from tripeptide sequences to millions of tetrapeptide and pentapeptide sequences, offering experimentalists an explicit roadmap for fine-tuning the aggregation behavior of short peptides for diverse applications, including hydrogels, emulsions, or pharmaceuticals.

Techno-Functions and Safety Concerns of Plant-Based Peptides in Food Matrices

Plant-based peptides (PBPs) benefit functional food development and environmental sustainability. Proteolysis remains the primary method of peptide production because it is a mild and nontoxic technique. However, potential safety concerns still emanate from toxic or allergenic sequences, amino acid racemization, iso-peptide bond formation, Maillard reaction, dose usage, and frequency. The main aim of this review is to investigate the techno-functions of PBPs in food matrices, as well as their safety concerns. The distinctive characteristics of PBPs exhibit their techno-functions for improving food quality and functionality by contributing to several crucial food formulations and processing. The techno-functions of PBPs include solubility, hydrophobicity, bitterness, foaming, oil-binding, and water-holding capacities, which subsequently affect food matrices. The safety and quality of foodstuff containing PBPs depend on the proper source of plant proteins, the selection of processing approaches, and compliance with legal regulations for allergen labeling and safety evaluations. The safety concerns in allergenicity and toxicity were discussed. The conclusion is that food technologists must apply safe limits and consider potential allergenic components generated during the development of food products with PBPs. Therefore, functional food products containing PBPs can be a promising strategy to provide consumers with wholesome health benefits.

Antioxidant Activity of Different Hop (Humulus lupulus L.) Genotypes

The antioxidant activity (AA) of hop extracts obtained from different hop genotypes (n = 14) was studied. For comparison, the purified β-acids-rich fraction and α-acids-with-β-acids-rich fraction were also used to test the antioxidative potential. The AA of purified hydroacetonic hop extracts was investigated using the Ferric Reducing Ability of Plasma (FRAP), Oxygen Radical Absorption Capacity (ORAC) and Intracellular Antioxidant (IA) methods. The FRAP values in different hop genotypes ranged between 63.5 and 101.6 μmol Trolox equivalent (TE)/g dry weight (DW), the ORAC values ranged between 1069 and 1910 μmol TE/g DW and IA potential values ranged between 52.7 and 118.0 mmol TE/g DW. Significant differences in AA between hop genotypes were observed with all three methods. AAs were determined using three different methods, which did not highly correlate with each other. We also did not find significant correlations between AA and different chemical components, which applies both to AA determined using individual methods as well as the total AA. Based on this fact, we assume that the synergistic or antagonistic effects between hop compounds have a more pronounced effect on AA than the presence and quantity of individual hop compounds.

RETRACTED: Hemp bioactive peptides: Nutrition, functional properties and action mechanisms to maximize their nutraceutical applications and future prospects

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/locate/withdrawalpolicy). This review article has been retracted at the request of the Editor in Chief and authors. The article has been retracted as it duplicates several figures from a paper that had already appeared in Trends in Food Science & Technology, Volume 127, September 2022, Pages 303-318, without giving appropriate credit to this paper. One of the conditions of submission of a paper for publication is that authors declare explicitly that their work is original and has not appeared in a publication elsewhere. Re-use of any data should be appropriately cited. As such this article falls short of the scientific quality requirement of the journal. The third author admits responsibility for the oversight and wishes to apologize to the readers and editors of Food Chemistry for the inconvenience. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.

The Effect of Erythritol on the Physicochemical Properties of Reformulated, High-Protein, and Sugar-Free Macarons Produced from Whey Protein Isolate Intended for Diabetics, Athletes, and Physically Active People

This study reports the possibility of obtaining sugar-free WPI-based macarons with erythritol addition. The whey protein isolate (WPI) solution (20%, w/v) was whipped, and erythritol was added to the foam at concentrations of 20, 40, and 60 g, with 125 g of almond flour. The rheological properties (τ, G', G″, and tan (δ)) and stability of the macaron batters before baking were evaluated. In order to produce the macarons, the batters were solidified at 147 °C for 12 min. The textural and surface properties (roughness and color), as well as the microstructures and water activities, were determined for the macarons. It was feasible to produce macarons over the entire range of the tested erythritol content. Even the smallest amount of erythritol (20 g) facilitated the preservation of the macaron structure. The medium erythritol concentration (40 g) improved the stability of the batters and their rheology and was the most effective for air pocket stabilization during baking; however, its largest addition (60 g) resulted in an increase in the final macaron volume. The increased erythritol addition improved mechanical properties and shelf life, producing a smoothing effect on the macaron surfaces and having a significant effect on their color co-ordinates.

A critical review on immunomodulatory peptides from plant sources; action mechanisms and recent advances

Plant protein components contribute positively to human well-being as they modulate the immune status of a consumer, especially when the enzymatic method is employed in order to release their bioactive peptides. These peptides are derived from plant-based foods such as soy, wheat, barley, rye, oats, rice, corn, sorghum, and millet, the famous staple foods around the world. Since these peptides are crucial to functional food among other key industries, the present study endeavored to scout for relevant information within the past three decades, using the Web of Science, Scopus, and Google search engines. In this review, first, the core of immunomodulation and types of immunomodulatory agents will be discussed, followed by the production of plant-based immunomodulatory peptides and their immunomodulatory mechanisms in cells, animals, and humans are also studied. Finally, applications and challenges associated with plant-based immunomodulatory peptides are put forward.

Exploration of the Nutritional and Functional Properties of Underutilized Grains as an Alternative Source for the Research of Food-Derived Bioactive Peptides

The estimated increase in world population will lead to a deterioration in global food security, aggravated in developing countries by hidden hunger resulting from protein deficiency. To reduce or avoid this crisis, a dietary shift towards the consumption of sustainable, nutrient-rich, and calorically efficient food products has been recommended by the FAO and WHO. Plant proteins derived from grains and seeds provide nutritionally balanced diets, improve health status, reduce poverty, enhance food security, and contain several functional compounds. In this review, the current evidence on the nutritional and functional properties of underutilized grains is summarized, focusing on their incorporation into functional foods and the role of their proteins as novel source of bioactive peptides with health benefits.

In vitro comparative evaluation of Tamarix gallica extracts for antioxidant and antidiabetic activity

Tamarix gallica known as Jhau is traditionally used as expectorant, liver tonic, laxative, astringent, and antidiarrheal. The current study was proposed to determine the in vitro antioxidant, antidiabetic properties of the methanolic, ethanolic, and aqueous extracts of Tamarix gallica arial part, subsequently the phytochemical evaluation. Hence, Tamarix gallica arial part extracts were extracted with methanol (MthTg), ethanol (EthTg), and distilled water (AqTg). Extracts phytochemical analysis were accomplished to identify the phenolic components (TPC and TFC). Extracts antioxidant property was evaluated by DPPH, FRAP, and ABTS assay. For antidiabetic property, α-amylase and α-glucosidase inhibitory activities were assessed. One Way ANOVA was applied statistically by means of software SPSS Statistics 23 and attained data were definite as mean ± standard deviation. Result revealed that EthTg have the maximum TPC and TFC levels than MthTg and AqTg. Antioxidant property in relations of DPPH (lowest IC₅₀ = 1.309 ± 0.31), FRAP (323.51 ± 2.32), and ABTS (266.97 ± 25.14) assay was also highest in EthTg. EthTg was also exposed highest α-amylase and α-glucosidase inhibition activity with lower IC₅₀ (1.116 ± 0.051; 0.402 ± 0.2, respectively). The extracts antioxidant and antidiabetic activities order was as EthTg > MthTg > AqTg. TFC and TPC also revealed directly proportional correlation with antioxidant, and antidiabetic properties of the Tamarix gallica arial part extracts. Results noticeably stated that the ethanolic extract of Tamarix gallica have the highest antioxidant and antidiabetic properties. Tamarix gallica has competency to reduce the oxidative stress and can be utilized in the management of diabetes.

Multi-Bioactivity of Protein Digests and Peptides from Oat (Avena sativa L.) Kernels in the Prevention of the Cardiometabolic Syndrome

The aim of this study was to characterize the digests and peptides derived from oat kernel proteins in terms of their major enzyme inhibitory activities related to the prevention of cardiometabolic syndrome. It also entailed the characteristics of antioxidant bioactivity of the analyzed material. The study was carried out using coupled in silico and in vitro methods. The additional goal was to investigate whether identified peptides can pervade Caco-2 cells. Based on the results of bioinformatic analysis, it was found that the selected oat proteins may be a potential source of 107 peptides with DPP-IV and/or ACE inhibitory and/or antioxidant activity. The duodenal digest of oat kernels revealed multiple activities. It inhibited the activities of the following enzymes: DPP-IV (IC₅₀ = 0.51 vs. 10.82 mg/mL of the intact protein), α-glucosidase (IC₅₀ = 1.55 vs. 25.20 mg/mL), and ACE (IC₅₀ = 0.82 vs. 34.52 mg/mL). The DPPH^• scavenging activity was 35.7% vs. 7.93% that of the intact protein. After in silico digestion of oat proteins, 24 peptides were selected for identification using LC-Q-TOF-MS/MS. Among them, 13 sequences were successfully identified. One of them, i.e., VW peptide, exhibited triple activities, i.e., DPP-IV and ACE inhibitory and DPPH^• scavenging activity. The multifunctional peptides: PW, TF, VF, and VW, were identified in the basolateral samples after transport experiments. Both in silico and in vitro analyses demonstrated that oat kernel proteins were the abundant sources of bioactive digests and peptides to be used in a diet for patients suffering from cardiometabolic syndrome.

Food Protein-Derived Antioxidant Peptides: Molecular Mechanism, Stability and Bioavailability

The antioxidant activity of protein-derived peptides was one of the first to be revealed among the more than 50 known peptide bioactivities to date. The exploitation value associated with food-derived antioxidant peptides is mainly attributed to their natural properties and effectiveness as food preservatives and in disease prevention, management, and treatment. An increasing number of antioxidant active peptides have been identified from a variety of renewable sources, including terrestrial and aquatic organisms and their processing by-products. This has important implications for alleviating population pressure, avoiding environmental problems, and promoting a sustainable shift in consumption. To identify such opportunities, we conducted a systematic literature review of recent research advances in food-derived antioxidant peptides, with particular reference to their biological effects, mechanisms, digestive stability, and bioaccessibility. In this review, 515 potentially relevant papers were identified from a preliminary search of the academic databases PubMed, Google Scholar, and Scopus. After removing non-thematic articles, articles without full text, and other quality-related factors, 52 review articles and 122 full research papers remained for analysis and reference. The findings highlighted chemical and biological evidence for a wide range of edible species as a source of precursor proteins for antioxidant-active peptides. Food-derived antioxidant peptides reduce the production of reactive oxygen species, besides activating endogenous antioxidant defense systems in cellular and animal models. The intestinal absorption and metabolism of such peptides were elucidated by using cellular models. Protein hydrolysates (peptides) are promising ingredients with enhanced nutritional, functional, and organoleptic properties of foods, not only as a natural alternative to synthetic antioxidants.

Micronized Dietary Okara Fiber: Characterization, Antioxidant, Antihyperglycemic, Antihyperlipidemic, and Pancreato-Protective Effects in High Fat Diet/Streptozotocin-Induced Diabetes Mellitus

Diabetes mellitus (DM) is a lifelong devastating and debilitating disease with serious chronic complications. Okara is a byproduct generated from soymilk or tofu production and it has been reported to have antioxidant and lipid-lowering effects. However, the antidiabetic effects and pancreatic β-cells' secretory functions of micronized okara fiber (MOF) have not been reported. Therefore, this study explored the antidiabetic effects and modulatory potentials of MOF on pancreatic β-cells' secretory functions in a high fat/high sugar/streptozotocin rat model of diabetes mellitus. Fiber-rich okara was prepared by removing fat and proteins from freshly obtained okara, followed by micronization. Fiber-rich okara was prepared, micronized, and characterized for hydrophobicity, thermal stability, structure-function relationship, and antioxidant potentials. We then established a rat model of DM and MOF and two doses (100 and 400 mg kg^-1) were administered to see its anti-DM effect. Four weeks of MOF supplementation significantly reduced blood glucose, increased serum insulin level, improved hepatorenal functions, glucose tolerance, and regenerated pancreatic β-cells in the treated DM rats. Furthermore, MOF significantly improved the pancreatic antioxidant defense system by significantly elevating glutathione peroxidase, catalase, and superoxide dismutase activities while depleting the malonaldehyde level in the pancreas of the treated diabetic rats. Our results indicated that MOF ameliorated DM by impeding hyperglycemia, hyperlipidemia, and oxidative stress and enhancing the secretory functions of the beta cells, suggesting that MOF might be used as a protective nutrient in DM.

Comparative biological analyses on kenger and kenger coffee as novel functional food products

Abstract

The current research was conducted to investigate neuroprotective, anticancer, antiproliferative and apoptotic DNA fragmentation potentials of the extracts obtained from aerial-parts, raw-fruits, and coffee samples (prepared by roasting and boiled-roasting) of kenger (Gundelia tournefortii var. armata). Neuroprotection capacities of the samples were screened against enzymes that are linked to the progression of Alzheimer's and Parkinson's diseases. Since the oxidative damage is closely related to the development of neurodegeneration and cancer, the extracts were also analyzed for their antioxidant activities. Anticancer and antiproliferative activities of the samples were evaluated towards A549, MCF-7, and HeLa cells, and they exhibited remarkable anticancer activities in dose-and time-dependent manners. Furthermore, the apoptotic activity regarding DNA fragmentation was also imaged. The extracts obtained from the aerial-parts and raw-fruits of kenger possessed the highest anticancer and antiproliferative activities on HeLa cells with the IC₅₀ values varied from 290.71 ± 0.69 to 342.46 ± 0.42, whilst kenger coffee samples had the weakest activity on the cell death towards MCF-7. However, the tested extracts exhibited strong antioxidant activities, in which the best reducing antioxidant capacity was defined in the raw-fruits and aerial-parts of the extracts. The roasted-coffee samples had the best inhibition on tyrosinase (88.26 ± 0.15%, p < 0.05), while the raw fruit-EtOH extract showed the highest inhibition on AChE and BChE enzymes (39.10 ± 2.01%, p < 0.01 and 72.69 ± 0.16%, p < 0.016, respectively). Consequently, research outputs provide noteworthy data on the usage of kenger for the nutraceutical and the healthy food industries.

Graphic abstract

Enhanced light harvesting, higher donor density, appropriate band bending, lowest charge transfer radius of C-Ag-ZnO hybrid signifies that efficient charge transfer and restriction to charge recombination leading to the enhanced PEC performance.

Production of egg white hydrolysate by digestion with pineapple bromelain: optimization, evaluation and antioxidant activity study

Chicken egg white is known to be an excellent source of good quality proteins to make hydrolysate with potential bioactive properties. Enzymatic digestion is a well-known method to produce protein hydrolysates; however, the type of enzyme determines the bioactive potential of the protein hydrolysates due to difference in their catalytic specificity. In this study, process optimization, production and evaluation of whole egg white protein hydrolysate (WEWPH) using pineapple bromelain through the Box-Behnken design were carried out. The design experiment (r 2 = 0.9557) displayed a significant (p < 0.01) effect of pH of egg white (9.0), hydrolysis time (24 h), and enzyme/substrate ratio (3.2 unit/g substrate) on hydrolysis and to form bioactive WEWPH. Antioxidant activity of the WEWPH was confirmed by DPPH radical scavenging assay. Gel filtration chromatography, SDS-PAGE and FTIR spectroscopy analysis of WEWPH revealed the digestion of egg white and the integrity of WEWPH in terms of secondary structure. The WEWPH exhibited strong scavenging activities of DPPH (EC50 = 238.3 µg/ml), ABTS ABTS (EC50 = 54.9 µg/ml), peroxyl (EC50 = 391.6 µg/ml) and superoxide radicals. The WEWPH also displayed reducing power and singlet oxygen quenching activity. These results reveal that the bioactive WEWPH could be a promising ingredient in health food and nutraceuticals.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-021-05188-0.

Phytochemical Screening, Antioxidant, and Inhibition Activity of Picrorhiza kurroa Against α-Amylase and α-Glucosidase

Picrorhiza kurroa (P.K) usually familiar as kutki is a well-known plant in the Ayurvedic system of medicine due to its reported activities including antidiabetic, antibacterial, antioxidant, antitumor, anti-inflammatory, and hepatoprotective. The current research was intended to evaluate the antioxidant, inhibition activity of the ethanolic, methanolic, and aqueous extracts of P.K roots against α-amylase and α-glucosidase in vitro, after the phytochemical analysis. For this purpose, P.K roots were extracted with ethanol (EthPk), methanol (MthPk), and distilled water (AqPk) and phytochemical study of the extracts were performed to recognize the total phenolic content (TPC) and total flavonoids content (TFC). Antioxidant capability of the extracts was assessed by FRAP, ABTS, and DPPH assay. α-amylase inhibitory and α-glucosidase inhibitory activities were also determined. Software SPSS-23 was used to statistically analyze with One Way ANOVA and results were stated as mean standard deviation. Result of the study showed that MthPk contained the maximum concentration of TPC and TFC than EthPk and AqEh. Antioxidants in terms of DPPH (lowest IC₅₀ = .894 ± .57), FRAP (612.54 ± 11.73) and ABTS (406.42 ± 4.02) assay was also maximum in MthPk. MthPk was also showed maximum inhibition activity against α-amylase and α-glucosidase with lowest IC₅₀ (.39 ± .41; .61 ± .24), respectively. The extracts α-amylase and α-glucosidase inhibitory activities order was as MthPk > EthPk> AqPk. Results clearly specified that the methanolic extract of Picrorhiza kurroa have the maximum antioxidant, α-amylase, and α-glucosidase inhibitory activities. A positive correlation of TPC, TFC with antioxidant, and α-amylase and α-glucosidase inhibition activities of the P.K roots were also shown. The plant has capability to diminish the oxidative stress and can be used to treat diabetes by inhibiting α-amylase and α-glucosidase actions.

Purification and Identification of Novel Antioxidant Peptides Isolated from Geoffroea decorticans Seeds with Anticoagulant Activity

Geoffroea decorticans is a xerophilous deciduous tree present in most arid forests of southern South America, which is commonly used in traditional medicine. The seeds of this tree have been previously investigated for their singular chemical composition, but their protein content has been poorly investigated. Herein, we report the isolation, purification, and characterization of a set of thermostable peptides derived from Geoffroea decorticans seeds (GdAPs) with strong antioxidant and anticoagulant activities. The most potent antioxidant peptides showed a half maximal inhibitory concentration (IC50) of 35.5 ± 0.3 µg/mL determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH). They also caused a dose-dependent prolongation of the aPTT clotting time with an IC50 value of ~82 µg/mL. Interestingly, MALDI-TOF/MS analysis showed the presence of three major peptides with low molecular weights of 2257.199 Da, 2717.165 Da, and 5422.002 Da. The derived amino-acid sequence of GdAPs revealed their unique structural features, exhibiting homology with various proteins present in the genome of Arachis hypogaea. All in all, our data suggest a direct applicability of GdAPs for pharmaceutical purposes.

Emulsifier peptides derived from seaweed, methanotrophic bacteria, and potato proteins identified by quantitative proteomics and bioinformatics

Global focus on sustainability has accelerated research into alternative non-animal sources of food protein and functional food ingredients. Amphiphilic peptides represent a class of promising biomolecules to replace chemical emulsifiers in food emulsions. In contrast to traditional trial-and-error enzymatic hydrolysis, this study utilizes a bottom-up approach combining quantitative proteomics, bioinformatics prediction, and functional validation to identify novel emulsifier peptides from seaweed, methanotrophic bacteria, and potatoes. In vitro functional validation reveal that all protein sources contained embedded novel emulsifier peptides comparable to or better than sodium caseinate (CAS). Thus, peptides efficiently reduced oil-water interfacial tension and generated physically stable emulsions with higher net zeta potential and smaller droplet sizes than CAS. In silico structure modelling provided further insight on peptide structure and the link to emulsifying potential. This study clearly demonstrates the potential and broad applicability of the bottom-up approach for identification of abundant and potent emulsifier peptides.

Food-Derived Bioactive Peptides with Antioxidative Capacity, Xanthine Oxidase and Tyrosinase Inhibitory Activity

Bioactive peptides (BPs) released by proteases from different food protein sources are often served as antioxidants in food applications. This study aims to investigate 11 BPs derived from fish and egg white as potential natural antioxidants by antioxidant activity assays. The kinetic activity of the BPs against xanthine oxidase (XOD) and tyrosinase was also analyzed. The antioxidative capacity of the BPs indicated that VWWW (VW4, mackerel meat), followed by IRW (IW3, egg white) and VKAGFAWTANQQLS (VS14, tuna backbone protein), possessed the highest antioxidant activity in 1,1-diphenyl-2-picrylhydrazyl radical (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) and reducing power (RP) assays. Both the free-radical scavenging score predicted from the AnOxPePred algorithm and the DPPH, ABTS and RP results indicated that VW4 was the best antioxidant. Furthermore, the XOD and tyrosinase inhibition by three selected peptides exhibited competitive patterns of effective inhibition. The half maximal inhibitory concentrations (IC50) of the peptides for XOD inhibition were 5.310, 3.935, and 1.804 mM for VW4, IW3, and VS14, respectively, and they could serve as competitive natural XOD inhibitors. The IC50 of the peptides for tyrosinase inhibition were 1.254, 2.895, and 0.595 mM for VW4, IW3, and VS14, respectively. Overall, VW4, IW3, and VS14 are potential antioxidants and natural XOD inhibitors for preventing milk-fat oxidation, and anti-browning sources for inhibiting food-derived tyrosinase oxidation.

Potential "biopeptidal" therapeutics for severe respiratory syndrome coronaviruses: a review of antiviral peptides, viral mechanisms, and prospective needs

Although great advances have been made on large-scale manufacturing of vaccines and antiviral-based drugs, viruses persist as the major cause of human diseases nowadays. The recent pandemic of coronavirus disease-2019 (COVID-19) mounts a lot of stress on the healthcare sector and the scientific society to search continuously for novel components with antiviral possibility. Herein, we narrated the different tactics of using biopeptides as antiviral molecules that could be used as an interesting alternative to treat COVID-19 patients. The number of peptides with antiviral effects is still low, but such peptides already displayed huge potentials to become pharmaceutically obtainable as antiviral medications. Studies showed that animal venoms, mammals, plant, and artificial sources are the main sources of antiviral peptides, when bioinformatics tools are used. This review spotlights bioactive peptides with antiviral activities against human viruses, especially the coronaviruses such as severe acute respiratory syndrome (SARS) virus, Middle East respiratory syndrome (MERS) virus, and severe acute respiratory syndrome coronavirus 2 (SARS-COV-2 or SARS-nCOV19). We also showed the data about well-recognized peptides that are still under investigations, while presenting the most potent ones that may become medications for clinical use.

Impact of in vitro gastrointestinal digestion on peptide profile and bioactivity of cooked and non-cooked oat protein concentrates

Oat (Avena sativa) is one of the most cultivated and consumed cereals worldwide. Recognized among cereals for its high protein content (12%-24%), it makes it an excellent source of bioactive peptides, which could be modified during processes such as heating and gastrointestinal digestion (GID). This work aims to evaluate the impact of heat treatment on the proteolysis of oat proteins and on the evolution of antioxidant peptide released during in vitro static GID, in terms of comparative analysis between cooked oat protein concentrate (COPC) and non-heated oat protein concentrate (OPC) samples. The protein extraction method and cooking procedure used showed no detrimental effects on protein quality. After GID, the proportion of free amino acids/dipeptides (<0.2 ​kDa) reached >40% for both samples (OPC and COPC), thus producing peptides with low molecular weight and enhanced bioactivity. Furthermore, during GID, the amino acid profile showed an increase in essential, positively-charged, hydrophobic and aromatic amino acids. At the end of GID, the reducing power of OPC and COPC increased >0.3 and 8-fold, respectively, in comparison to the non-digested samples; while ABTS•+ and DPPH• showed a >20-fold increase. Fe2+ chelating capacity of OPC and COPC was enhanced >4 times; similarly, Cu2+ chelation showed a >19-fold enhancement for OPC and >10 for COPC. β-carotene bleaching activity was improved 0.8 times in OPC and >9 times in COPC; the oxygen radical antioxidant capacity assay increased 2 times in OPC and >4.7 times in COPC, respectively. This study suggests that OPC after cooking and GID positively influenced the nutritional and bioactive properties of oat peptides. Thus, COPC could be used as a functional food ingredient with health-promoting effects, as hydrothermal treatment is frequently used for this type of cereals.

Soy bioactive peptides and the gut microbiota modulation

The balance of protein, carbohydrate, and fat affect the composition and functions of the gut microbiota. The complexities involved thereof require insights into the roles and impacts of individual dietary components due to the difficulty of defining such in a group of others. Peptides and proteins from several animal and plant sources have been widely explored in relation to the gut microbiome modulation, but the effects of soy peptides and other soy derivatives on the gut microbiota are largely unexplored. This piece considered an overview of the production and interventions of soy bioactive peptides on gut, as they affect the composition and functions of the gut microorganisms. A mini review on the production of soy protein hydrolysates/peptides and highlights of the most recent knowledge regarding their physiological effects on host's gut microbiota cum health were investigated. Overall deductions and research gaps were critically evaluated for futuristic interventions and relevance. Key points • Diet affects the composition of gut microorganisms. • Modulation of the gut microbiota by soy biopeptides is described. • Critical deductions on personal and commercial use are provided.