Extraction of antioxidant peptides from rice dreg protein hydrolysate via an angling method

Recent progress in plant-based proteins: From extraction and modification methods to applications in the food industry

Plant proteins can meet consumers' demand for healthy and sustainable alternatives to animal proteins. It has been reported to possess numerous health benefits and is widely used in the food industry. However, conventional extraction methods are time-consuming, energy-intensive, as well as environmentally unfriendly. Plant proteins are also limited in application due to off-flavors, allergies, and anti-nutritional factors. Therefore, this paper discusses the challenges and limitations of conventional extraction processes. The current advances in green extraction technologies are also summarized. In addition, methods to improve the nutritional value, bioactivity, functional and organoleptic properties of plant proteins, and strategies to reduce their allergenicity are mentioned. Finally, examples of applications of plant proteins in the food industry are presented. This review aims to stimulate thinking and generate new ideas for future research. It will also provide new ideas and broad perspectives for the application of plant proteins in the food industry.

Recent progress in the preparation of bioactive peptides using simulated gastrointestinal digestion processes

Bioactive peptides (BAPs) represent a unique class of peptides known for their extensive physiological functions and their role in enhancing human health. In recent decades, owing to their notable biological attributes such as antioxidant, antihypertensive, antidiabetic, and anti-inflammatory activities, BAPs have received considerable attention. Simulated gastrointestinal digestion (SGD) is a technique designed to mimic physiological conditions by adjusting factors such as digestive enzymes and their concentrations, pH levels, digestion duration, and salt content. Initially established for analyzing the gastrointestinal processing of foods or their constituents, SGD has recently become a preferred method for generating BAPs. The BAPs produced via SGD often exhibit superior biological activity and stability compared with those of BAPs prepared via other methods. This review offers a comprehensive examination of the recent advancements in BAP production from foods via SGD, addressing the challenges of the method and outlining prospective directions for further investigation.

Extraction of antimicrobial peptides from pea protein hydrolysates by sulfonic acid functionalized biochar

The extraction methods for antimicrobial peptides (AMPs) from plants are varied, but the absence of a standardized and rapid technique remains a challenge. In this study, a functionalized biochar was developed and characterized for the extraction of AMPs from pea protein hydrolysates. The results indicated that the biochar mainly enriched AMPs through electrostatic interaction, hydrogen bonding and pore filling. Then three novel cationic antimicrobial peptides were identified, among which the RDLFK (Arg-Asp-Leu-Phe-Lys) had the greatest inhibitory effect against Staphylococcus aureus and Bacillus subtilis, showcasing IC50 value of 2.372 and 1.000 mg/mL, respectively. Additionally, it was found that RDLFK could damage bacterial cell membranes and penetrate the cells to inhibit DNA synthesis. These results provided that the biochar-based extraction method presents an efficient and promising avenue for isolating AMPs, addressing a critical gap in the current methodologies for their extraction from plant sources.

Enhancing storage stability of pea peptides through encapsulation in maltodextrin and gum tragacanth via monitoring scavenge ability to free radicals

Pea peptides can lead to degradation through oxidation, deamidation, hydrolysis, or cyclization during production, processing, and storage, which in turn limit their broader application. To stabilize pea peptides, this study employed spray drying technology to create a pea peptide micro-encapsule using maltodextrin, gum tragacanth, and pea peptides. Four key factors, including polysaccharide ratio, glycopeptide ratio, solid-liquid ratio, and inlet temperature, were optimized to enhance the antioxidant properties of the pea peptide micro-encapsule. The results indicated that the utilization of maltodextrin and gum tragacanth significantly improves the storage stability and antioxidant activity of pea peptides. Moreover, optimal storage stability for pea peptides was achieved with a polysaccharide ratio of 9:1, a glycopeptide ratio of 10:1, a solid-liquid ratio of 4:40, and an inlet temperature of 180 °C. After 60 days of storage, the encapsulated pea peptides maintained 70.22 %, 25.19 %, and 40.32 % for scavenging abilities to hydroxyl radical, superoxide anion, and ABTS radical, respectively. In contrast, the unencapsulated pea peptides showed a decline to 47.02 %, 0 %, and 24.46 % in the same antioxidant activities after storage. These findings underscore the potential of spray drying technology to enhance the functional properties of pea peptides for various applications.

Enrichment of antioxidant peptide from rice protein hydrolysates via rice husk derived biochar

In this study, rice husk biochar was engineered with abundant iron ion sites to enhance the enrichment of antioxidant peptides from rice protein hydrolysates through metal-chelating interactions. The π-π interactions and metal ion chelation were identified as the primary mechanisms for the enrichment process. Through peptide sequencing, four peptides were identified: LKFL (P1: Leu-Lys-Phe-Leu), QLLF (P2: Gln-Leu-Leu-Phe), WLAYG (P3: Trp-Leu-Ala-Tyr-Gly), and HFCGG (P4: His-Phe-Cys-Gly-Gly). The vitro analysis and molecular docking revealed that peptides P1-P4 possessed remarkable scavenging ability against radicals and Fe2+ chelating ability. Notably, peptide P4 showed radical scavenging activity comparable to glutathione (GSH) against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis-3-ethylbenzthiazoline-6-sulphonate (ABTS) radicals. Cellular experiments further confirmed that peptide P4 effectively protected HepG2 cells from oxidative stress-induced damage. The modified rice husk biochar proved to be an effective means for enriching rice antioxidant peptides from protein hydrolysates.

New Insights into Antioxidant Peptides: An Overview of Efficient Screening, Evaluation Models, Molecular Mechanisms, and Applications

Antioxidant peptides are currently a hotspot in food science, pharmaceuticals, and cosmetics. In different fields, the screening, activity evaluation, mechanisms, and applications of antioxidant peptides are the pivotal areas of research. Among these topics, the efficient screening of antioxidant peptides stands at the forefront of cutting-edge research. To this end, efficient screening with novel technologies has significantly accelerated the research process, gradually replacing the traditional approach. After the novel antioxidant peptides are screened and identified, a time-consuming activity evaluation is another indispensable procedure, especially in in vivo models. Cellular and rodent models have been widely used for activity evaluation, whilst non-rodent models provide an efficient solution, even with the potential for high-throughput screening. Meanwhile, further research of molecular mechanisms can elucidate the essence underlying the activity, which is related to several signaling pathways, including Keap1-Nrf2/ARE, mitochondria-dependent apoptosis, TGF-β/SMAD, AMPK/SIRT1/PGC-1α, PI3K/Akt/mTOR, and NF-κB. Last but not least, antioxidant peptides have broad applications in food manufacture, therapy, and the cosmetics industry, which requires a systematic review. This review introduces novel technologies for the efficient screening of antioxidant peptides, categorized with a new vision. A wide range of activity evaluation assays, encompassing cellular models, as well as rodent and non-rodent models, are provided in a comprehensive manner. In addition, recent advances in molecular mechanisms are analyzed with specific cases. Finally, the applications of antioxidant peptides in food production, therapy, and cosmetics are systematically reviewed.

Antioxidant peptides, the guardian of life from oxidative stress

Reactive oxygen species (ROS) are produced during oxidative metabolism in aerobic organisms. Under normal conditions, ROS production and elimination are in a relatively balanced state. However, under internal or external environmental stress, such as high glucose levels or UV radiation, ROS production can increase significantly, leading to oxidative stress. Excess ROS production not only damages biomolecules but is also closely associated with the pathogenesis of many diseases, such as skin photoaging, diabetes, and cancer. Antioxidant peptides (AOPs) are naturally occurring or artificially designed peptides that can reduce the levels of ROS and other pro-oxidants, thus showing great potential in the treatment of oxidative stress-related diseases. In this review, we discussed ROS production and its role in inducing oxidative stress-related diseases in humans. Additionally, we discussed the sources, mechanism of action, and evaluation methods of AOPs and provided directions for future studies on AOPs.

Protein Hydrolysates from Fishery Processing By-Products: Production, Characteristics, Food Applications, and Challenges

Fish processing by-products such as frames, trimmings, and viscera of commercial fish species are rich in proteins. Thus, they could potentially be an economical source of proteins that may be used to obtain bioactive peptides and functional protein hydrolysates for the food and nutraceutical industries. The structure, composition, and biological activities of peptides and hydrolysates depend on the freshness and the actual composition of the material. Peptides isolated from fishery by-products showed antioxidant activity. Changes in hydrolysis parameters changed the sequence and properties of the peptides and determined their physiological functions. The optimization of the value of such peptides and the production costs must be considered for each particular source of marine by-products and for their specific food applications. This review will discuss the functional properties of fishery by-products prepared using hydrolysis and their potential food applications. It also reviews the structure-activity relationships of the antioxidant activity of peptides as well as challenges to the use of fishery by-products for protein hydrolysate production.

Characterization of the structure, antioxidant activity and hypoglycemic activity of soy (Glycine max L.) protein hydrolysates

This study aimed to hydrolyze soy isolate protein (SPI) using five enzymes (alcalase, pepsin, trypsin, papain, and bromelain) in order to obtain five enzymatic hydrolysates and to elucidate the effect of enzymes on structural and biological activities of the resulting hydrolysates. The antioxidant and hypoglycemic activities of the soy protein isolate hydrolysates (SPIEHs) were evaluated through in silico analysis, revealing that the alcalase hydrolysate exhibited the highest potential, followed by the papain and bromelain hydrolysates. Subsequently, the degree of hydrolysis (DH), molecular weight distribution (MWD), amino acid composition, structure, antioxidant activities, and hypoglycemic activity in vitro of SPIEHs were analyzed. After enzymatic treatment, the particle size, polymer dispersity index (PDI), ζ-potentials, β-sheet content and α-helix content of SPIEHs was decreased, and the maximum emission wavelength of all SPIEHs exhibited red-shifted, which all suggesting the structure of SPIEHs was unfolded. More total amino acids (TAAs), aromatic amino acids (AAAs), and hydrophobic amino acids (HAAs) were found in alcalase hydrolysate. For 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, metal ion chelating activity, α-glucosidase inhibitory activity and α-amylase inhibitory activity, alcalase hydrolysate had the lowest IC50; alcalase hydrolysate and papain hydrolysate had the lowest IC50 for hydroxyl radical scavenging activity. Physiological activity of SPIEHs was evaluated thoroughly by 5-Axe cobweb charts, and the results revealed that alcalase hydrolysate exhibited the greatest biological activities.

Antioxidant and Renin Inhibitory Activities of Peptides from Food Proteins on Hypertension: A Review

Hypertension is a condition induced by oxidative stress causing an alteration in the endothelium, which increases the risk of suffering from other degenerative diseases. This review compiles the findings on peptides from food proteins with antioxidant and antihypertensive activities. Antihypertensive peptides are mainly focused on renin inhibition. Peptides containing hydrophobic amino acids have antioxidant and renin inhibitory activities, as reported by studies on the biological activity of peptides from various food sources evaluated separately and simultaneously. Peptides from food sources can present multiple biological activities. Moreover, antioxidant peptides have the potential to be evaluated against renin, offering an alternative for hypertension therapy without causing adverse side effects.

Biocompatible Palladium Nanoparticles Prepared Using Vancomycin for Colorimetric Detection of Hydroquinone

Hydroquinone poses a major threat to human health and is refractory to degradation, so it is important to establish a convenient detection method. In this paper, we present a novel colorimetric method for the detection of hydroquinone based on a peroxidase-like Pd nanozyme. The vancomycin-stabilized palladium nanoparticles (Van-Pd_n NPs, n = 0.5, 1, 2) were prepared using vancomycin as a biological template. The successful synthesis of Van-Pd_n NPs (n = 0.5, 1, 2) was demonstrated by UV-vis spectrophotometry, transmission electron microscopy, and X-ray diffraction. The sizes of Pd nanoparticles inside Van-Pd_0.5 NPs, Van-Pd₁ NPs, and Van-Pd₂ NPs were 2.6 ± 0.5 nm, 2.9 ± 0.6 nm, and 4.3 ± 0.5 nm, respectively. Furthermore, Van-Pd₂ NPs exhibited excellent biocompatibility based on the MTT assay. More importantly, Van-Pd₂ NPs had good peroxidase-like activity. A reliable hydroquinone detection method was established based on the peroxidase-like activity of Van-Pd₂ NPs, and the detection limit was as low as 0.323 μM. Therefore, vancomycin improved the peroxidase-like activity and biocompatibility of Van-Pd₂ NPs. Van-Pd₂ NPs have good application prospects in the colorimetric detection of hydroquinone.

Botanical Origins and Antioxidant Activities of Two Types of Flavonoid-Rich Poplar-Type Propolis

(1) Background: Propolis has attracted attention in recent years due to its important pharmacological effects. The present study aimed to investigate the botanical origins of 39 propolis samples and evaluate their antioxidant activities; (2) Methods: A HPLC-PDA system was used to analyze the phenolic compositions of propolis and poplar bud resin samples. The antioxidant activities of propolis samples were evaluated by oxygen radical absorption capacity (ORAC) and superoxide anion free radical scavenging capacity assay; (3) Results: Our study shows that 17 propolis samples were characterized by five predominant flavonoids, including 5-methoxy pinobanksin, pinobanksin, pinocembrin, pinobanksin-3-acetate, and chrysin, while 22 propolis samples were characterized by four flavonoids (pinobanksin, pinocembrin, pinobanksin-3-acetate, and chrysin). The average contents of characteristic flavonoids reached up to over 70% and 65% of total phenolics, respectively. Furthermore, the botanical origins of the two types of propolis samples were identified as Populus × euramericana cv. 'Neva' and Populus Simonii × P. nigra, respectively; (4) Conclusions: Most notably, our results reveal that these propolis samples presented excellent antioxidant activities due to their high contents of flavonoid. These flavonoid-rich propolis samples can thus be used to develop low-allergen and high-antioxidant nutraceuticals.

Structural Identification and Antioxidant Activity of Loach Protein Enzymatic Hydrolysates

Loach, rich in nutrients, such as proteins, amino acids, and mineral elements, is being gradually favored by consumers. Therefore, in this study, the antioxidant activity and structural characteristics of loach peptides were comprehensively analyzed. The loach protein (LAP) with a molecular weight between 150 and 3000 Da was graded by ultrafiltration and nanofiltration processes, which exhibited excellent scavenging activity against DPPH radical (IC50 2.91 ± 0.02 mg/mL), hydroxyl radical (IC50 9.95 ± 0.03 mg/mL), and superoxide anion radical (IC50 13.67 ± 0.33 mg/mL). Additionally, LAP was purified by gel filtration chromatography, and two principal components (named as LAP-I and LAP-II) were isolated. A total of 582 and 672 peptides were identified in LAP-I and LAP-II, respectively, through structural analysis. The XRD results revealed that LAP-I and LAP-II had an irregular amorphous structure. The 2D-NMR spectroscopy results suggested that LAP-I had a compact stretch conformation in the D₂O solution, while LAP-II had a folded conformation. Overall, the study results suggested that loach peptide could be a potential antioxidant agent and might provide valuable information for chain conformation and antioxidant mechanism research further.

Alanine Substitution to Determine the Effect of LR5 and YR6 Rice Peptide Structure on Antioxidant and Anti-Inflammatory Activity

The relationship between the structure of peptides LR5 (LHKFR) and YR6 (YGLYPR) and their antioxidant and anti-inflammatory activity remains unclear. Herein, leucine, tyrosine, proline, and phenylalanine at different positions in the peptides were replaced by Alanine (Ala), and two new pentapeptides (AR5 and LAR5) and four hexapeptides (AGR6, YAR6, YLR6, and YGR6) were obtained. The effect of Ala replacement on the hydrophobicity, cytotoxicity, NO inhibition rate, and active oxygen radical scavenging ability of these peptides and their antioxidant and anti-inflammatory abilities were investigated. The results indicated that the hydrophobicity of the peptides was associated with their amino acid composition and their specific sequence. However, hydrophobicity had no significant effect on cytotoxicity. Ala replacement was shown to enhance hydrophobicity and consequently increased the antioxidant and anti-inflammatory activity of the peptides. The molecular docking studies indicated that the amino acid interactions of the peptide with the Keap1 protein influenced the hydrophobicity and thus affected the antioxidant activity of the peptide.

Silver Carp (Hypophthalmichthys molitrix) Scales Collagen Peptides (SCPs): Preparation, Whitening Activity Screening and Characterization

This study involves the preparation of scale collagen peptides (SCPs) with whitening activity from silver carp (Hypophthalmichthys molitrix) and their characterization and peptide sequence identification. In this article, scanning electron microscopy (SEM) was used to observe structure changes of sliver carp scales; enzymatic hydrolysis was optimized through protease screening and response surface optimization. The ultrafiltration was used to separate SCPs and the whitening activity was comprehensively evaluated using radical scavenging rate and tyrosinase-inhibiting activity, among others. An optimal component was characterized and identified using various modern spectral analysis techniques. The results showed that the surface of silver carp scales after decalcification was smooth and clear. The pepsin had the highest peptide yield and tyrosinase-inhibiting activity (90.01% and 82.25%, respectively). The optimal enzymatic hydrolysis conditions were an enzyme dosage of 16.1%, a solid–liquid ratio of 1:15.6 and a time of 4.9 h. The proportions of hydrophobic and basic amino acids in the peptide composition were 32.15% and 13.12%, respectively. Compared with SCPs2, SCPs1 (6096.68–9513.70 Da) showed better ·OH scavenging ability, tyrosinase-inhibiting activity and moisture absorption. SCPs1 was a macromolecular fragment of type I collagen with a triple helix structure, containing three peptide sequences with the potential for tyrosinase activity inhibition (AGPPGADGQTGQRGE, SGPAGIAGPAGPRGPAGPNGPPGKD and KRGSTGEQGSTGPLGMRGPRGAA). These results show that SCPs1 is a collagen peptide product with whitening potential.

Insight into Antioxidant Activity and Peptide Profile of Jinhua Ham Broth Peptides at Different Cooking Times

This present study aimed to investigate the effects of various cooking times (1 h, 1.5 h, 2 h, 2.5 h, named as JHBP-1, JHBP-1.5, JHBP-2, JHBP-2.5) on the antioxidant activity and peptide profile of Jinhua ham broth peptides (JHBP). The peptides extracted from uncooked ham were used as an uncooked group with the name of JHBP-0. The results revealed that the antioxidant efficacy in the four cooked groups changed dramatically compared to JHBP-0. After cooking, the DPPH radical scavenging activity, hydroxyl radical scavenging activity and superoxide anion radical scavenging activity decreased, except for the Fe2+ chelation and ABTS+ scavenging capacity which increased significantly. However, the cooked groups still showed a strong antioxidant capacity. In particular, the superoxide anion radical scavenging ability and the Fe2+ chelation action were significantly stronger compared to glutathione (GSH) and butylated hydroxytoluene (BHT) (p < 0.05). JHBP-1.5 also displayed stronger antioxidant capacity than the other three cooked groups, and its secondary structure and mass distribution changed significantly after cooking, specifically with an increased proportion of helix and <1 kDa peptides. Moreover, the constitution of free amino acids (FAAs) and the types of peptides released in the broth increased significantly with a longer cooking time. In total, 1306 (JHBP-0), 1352 (JHBP-1), 1431 (JHBP-1.5), 1500 (JHBP-2), and 1556 (JHBP-2.5) peptide sequences were detected using LC-MC/MC. The proportion of <1 kDa peptides also gradually increased as the cooking time extended, which is consistent with the molecular weight distribution measurements.

Isolation, identification, and characterization of corn-derived antioxidant peptides from corn fermented milk by Limosilactobacillus fermentum

Dairy-derived peptides and corn-derived peptides have been identified as essential ingredients for health promotion in the food industry. The hydrolysis based on lactic acid bacteria (LAB) protease system is one of the most popular methods to prepare bioactive peptides. The objectives of this paper are to develop antioxidant fermented milk and to obtain natural antioxidant peptides. In our study, LAB with antioxidant capacity were screened in vitro, and the corn fermented milk with antioxidant capacity was achieved by the traditional fermentation method. Fermented milk was purified by ultrafiltration and molecular sieve, and identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Our findings demonstrate that Limosilactobacillus fermentum L15 had a scavenging capacity of more than 80% of DPPH radicals, Trolox equivalent antioxidant capacity (TEAC) of 0.348 ± 0.005 mmol/L. Meanwhile, the peptide content of corn fermented milk prepared with L. fermentum L15 was 0.914 ± 0.009 mg/mL and TAEC of 0.781 ± 0.020 mmol/L. Particularly important, IGGIGTVPVGR and LTTVTPGSR isolated and extracted from fermented milk were found to have antioxidant capacity for the first time. The synthetic peptides IGGIGTVPVGR and LTTVTPGSR demonstrated a scavenging capacity of 70.07 ± 2.71% and 70.07 ± 2.77% for DPPH radicals and an antioxidant capacity of 0.62 ± 0.01 mmol/L and 0.64 ± 0.02 mmol/L Trolox equivalent, respectively. This research provides ideas and basis for the development and utilization of functional dairy products.

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.

Separation of soy isoflavones from soy sauce residue by MIL-100(Fe)

Soy sauce residue (SSR) is a valuable biological resource, which contains soy isoflavones (SIs) with antioxidant activity and can be used to scavenge radicals. Herein, MIL-100(Fe) was synthesized for the extraction of SIs from SSR. Under the optimal adsorption conditions, the adsorption capacity of MIL-100(Fe) for SIs was 51.81 mg/g, which could achieve a purity of 56.17% and a recovery of 93.8%. These results demonstrated MIL-100(Fe) possessed effective properties of adsorption and purification for SIs. The content of SIs in the purified product was 167 times than that of SSR. The purified total SIs had a good antioxidant activity. The established method had a good scavenging ability toward 2, 2-diphenyl-1-picrylhydrazyl, superoxide and hydroxyl radicals, with IC₅₀ values of 0.177, 0.116 and 0.082 mg/mL, respectively. Besides, the ferrous ion chelating potency was better than others, with IC₅₀ values of 0.63 ± 0.0044 mg/mL. The established method was suitable for large-scale separation of purified total SIs and provided a reference for purification of bioactive factors from complex substrates.

Plant-derived proteins as a sustainable source of bioactive peptides: recent research updates on emerging production methods, bioactivities, and potential application

The development of novel protein sources to compensate for the expected future shortage of traditional animal proteins due to their high carbon footprint is a major contemporary challenge in the agri-food industry currently. Therefore, both industry and consumers are placing a greater emphasis on plant proteins as a sustainable source of protein to meet the growing nutritional demand of ever increasing population. In addition to being key alternatives, many plant-based foods have biological properties that make them potentially functional or health-promoting foods, particularly physiologically active peptides and proteins accounting for most of these properties. This review discusses the importance of plant-based protein as a viable and sustainable alternative to animal proteins. The current advances in plant protein isolation and production and characterization of bioactive hydrolysates and peptides from plant proteins are described comprehensively. Furthermore, the recent research on bioactivities and bioavailability of plant protein-derived bioactive peptides is reviewed briefly. The limitations of using bioactive peptides, regulatory criteria, and the possible future applications of plant protein-derived bioactive peptides are highlighted. This review may help understand plant proteins and their bioactive peptides and provide valuable suggestions for future research and applications in the food industry.

Recent research progress of biologically active peptides

With the rapid development of molecular biology and biochemical technology, great progress has been made in the study of peptides. Peptides are easy to digest and absorb, with lowering of blood pressure and cholesterol, improving immunity, regulating hormones, antibacterial, and antiviral effects. Peptides also have physiological regulation and biological metabolism functions with applications in the fields of feed production and biomedical research. In the future, the research focus of bioactive peptides will focus on their efficient preparation and application. This article introduces a comprehensive review of the types, synthesis, functionalization, and bio-related applications of bioactive peptides. For this aim, we introduced in detail various biopeptides and then presented the production methods of bioactive peptides, such as enzymatic synthesis, microbial fermentation, chemical synthesis, and others. The applications of bioactive peptides for anticancers, immune therapy, antibacterial, and other applications have been introduced and discussed. And discussed the development prospects of biologically active peptides.

Extraction and Identification of Three New Urechis unicinctus Visceral Peptides and Their Antioxidant Activity

The viscera of Urechis unicinctus with polypeptides, fatty acids, and amino acids are usually discarded during processing to food. In order to improve the utilization value of the viscera of Urechis unicinctus and avoid resource waste, antioxidant polypeptides were isolated from the viscera of Urechis unicinctus. First, a protein hydrolysate of Urechis unicinctus (UUPH) was prepared by ultrasonic-assisted enzymatic hydrolysis, and the degree of hydrolysis was as high as 79.32%. Subsequently, three new antioxidant peptides (P1, P2, and P3) were purified from UUPH using ultrafiltration and chromatography, and their amino acid sequences were identified as VTSALVGPR, IGLGDEGLRR, TKIRNEISDLNER, respectively. Then, the antioxidant activity of the polypeptide was predicted by the structure-activity relationship and finally verified by experiments on eukaryotic cells. The P1 peptide exhibited the strongest antioxidant activity among these three antioxidant peptides. Furthermore, P1, P2, and P3 have no toxic effect on RAW264.7 cells at the concentration of 0.01~2 mg/mL and can protect RAW264.7 cells from H2O2-induced oxidative damage in a concentration-dependent manner. These results suggested that these three new antioxidant peptides were isolated from the viscera of Urechis unicinctus, especially the P1 peptide, which might serve as potential antioxidants applied in health-derived food or beverages. This study further developed a new use of the by-product of Urechis unicinctus, which improved the comprehensive utilization of marine biological resources.

Industrially Produced Rice Protein Ameliorates Dextran Sulfate Sodium-Induced Colitis via Protecting the Intestinal Barrier, Mitigating Oxidative Stress, and Regulating Gut Microbiota

Inflammatory bowel disease (IBD) poses a threat to health and compromises the immune system and gut microflora. The present study aimed to explore the effects of rice protein (RP) purified from rice dregs (RD) on acute colitis induced by dextran sulfate sodium (DSS) and the underlying mechanisms. Results showed that RP treatment could alleviate the loss of body weight, colon shortening and injury, and the level of disease activity index, repair colonic function (claudin-1, ZO-1 and occludin), regulate inflammatory factors, and restore oxidative balance (malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD), and total antioxidant capability (T-AOC)) in mice. Also, RP treatment could activate the Kelch-like ECH-associating protein 1 (Keap1)-nuclear factor E2-related factor 2 (Nrf2) signaling pathway, mediate the expression of downstream antioxidant protease (NQO-1, HO-1, and Gclc), regulate gut microbiota by enhancing the relative abundance of Akkermansia and increasing the value of F/B, and adjust short-chain fatty acid levels to alleviate DSS-induced colitis in mice. Thus, RP may be an effective therapeutic dietary resource for ulcerative colitis.

Bioactive peptides of plant origin: distribution, functionality, and evidence of benefits in food and health

The multiple functions of peptides released from proteins have immense potential in food and health. In the past few decades, research interest in bioactive peptides of plant origin has surged tremendously, and new plant-derived peptides are continually discovered with advances in extraction, purification, and characterization technology. Plant-derived peptides are mainly extracted from dicot plants possessing bioactive functions, including antioxidant, cholesterol-lowering, and antihypertensive activities. Although the distinct functions are said to depend on the composition and structure of amino acids, the practical or industrial application of plant-derived peptides with bioactive features is still a long way off. In summary, the present review mainly focuses on the state-of-the-art extraction, separation, and analytical techniques, functional properties, mechanism of action, and clinical study of plant-derived peptides. Special emphasis has been placed on the necessity of more pre-clinical and clinical trials to authenticate the health claims of plant-derived peptides.

Plant polypeptides: A review on extraction, isolation, bioactivities and prospects

The application of traditional Chinese medicine has a long history in China with unique advantages and functions. With the rapid development of separation and purification technologies, more and more polypeptide compounds with specific biological activity and medicinal value were isolated from natural plants. The plant polypeptides have a lot of biological activities, such as antitumor effect, antioxidize effect, antibacterial effect, hypoglycemic effect, blood pressure lowering effect, lipid-lowering effect, anti-fatigue effect, and so on. This review summarized the extraction method, purification method, biological activities, and prospects of plant polypeptides, providing a basis for further study of plant polypeptides.

Photocatalytic degradation of imidacloprid by optimized Bi2WO6/NH2-MIL-88B(Fe) composite under visible light

Imidacloprid as a widely used neonicotinoid insecticide can cause harmful pesticide residue inevitably. Metal-organic frameworks (MOFs) were innovatively composited to improve the light absorption and degradation performance of Bi₂WO₆ semiconductor, which expanded the photodegradation application in solving environmental problems. Based on the synergistic effect of Bi₂WO₆ and NH₂-MIL-88B(Fe), a Bi₂WO₆/NH₂-MIL-88B(Fe) (BNM) heterojunction photocatalyst with high-performance of photocatalytic degradation activities was successfully synthesized. The optimized BNM catalyst had a good degradation rate under visible light, which was mainly caused by generation of the active ·OH. Transient photocurrent response and electrochemical impedance tests verified that 1:2 BNM exhibits a highest charge separation and a lowest carrier recombination rate which were favorable to the photocatalytic activity. Cycle experiments show that the composite photocatalyst had good reusability and stability which were very important for potential industry applications.

Neuroprotective effects of fermented yak milk-derived peptide LYLKPR on H2O2-injured HT-22 cells

This study explored the neuroprotective effect of the peptide LYLKPR derived from fermented yak milk by Lactiplantibacillus plantarum JLAU103 on H2O2-injured HT-22 cells.

Identification of three novel antioxidative peptides from Auxenochlorella pyrenoidosa protein hydrolysates based on a peptidomics strategy

Auxenochlorella pyrenoidosa is recognized as a potential sustainable protein material in food industry, however, its application remains still very limited. Herein, this study aimed to investigate the antioxidative properties of Auxenochlorella pyrenoidosa protein hydrolysates and identify novel antioxidative peptides from protein hydrolysates through a workflow mainly including enzymatic hydrolysis, peptidome quantification, quantitative structure-activity relationship (QSAR) modeling, in silico screening, and validation. Three novel antioxidative peptides including AGWACLVG, IDLAY and YPLDL were identified from protein hydrolysates by papain with the hydrolysis time of 4 h, in which, AGWACLVG showed strong 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity with the IC₅₀ value of 68.88 µM and Trolox equivalent antioxidative capacity of 6.20 ± 0.23 mmol TE/g. This study suggested that Auxenochlorella pyrenoidosa protein hydrolysates could be used as potential antioxidative ingredients in food industry, and the identification of novel antioxidative peptides would contribute to the construction of more robust QSAR models in the future.

Peroxidase-mimetic activity of a nanozyme with uniformly dispersed Fe3O4 NPs supported by mesoporous graphitized carbon for determination of glucose

A Fe₃O₄/mesoporous graphitized carbon (Fe₃O₄/m-GC) composite was prepared through a facile calcination method with iron-based metal-organic frameworks (Fe-MOFs) as a sacrificial template. After carbonization, the Fe₃O₄ nanoparticles were uniformly dispersed in the mesoporous carbon support, resulting in spatial structural stability. The mesoporous carbon support obtained was highly graphitized and exhibited eminent electrical conductivity, which accelerated the electron transfer between the Fe₃O₄ nanoparticles by Fe(II)/Fe(III) redox cycles and m-GC by C = C_sp2/C-C_sp3 redox cycles, leading to the excellent peroxidase-mimetic activity of Fe₃O₄/m-GC. K_m values for tetramethylbenzidine (TMB) and H₂O₂ were 26.8 and 15.8 times lower than that of natural horseradish peroxidase, respectively. Taking advantage of the peroxidase-mimetic activity of Fe₃O₄/m-GC, a colorimetric assay was fabricated for detecting glucose in the range 0.5 ~ 200 μM, with a limit of detection of 0.24 μM. Fig 1 A Schematic illustration of the preparation process of Fe₃O₄/m-GC, B schematic illustration of a proposed synergistic catalytic mechanism of TMB oxidation by Fe₃O₄/m-GC.

Functional Hybrid Micro/Nanoentities Promote Agro-Food Safety Inspection

The rapid development of nanomaterials has provided a good theoretical basis and technical support to solve the problems of food safety inspection. The combination of functionalized composite nanomaterials and well-known detection methods is gradually applied to detect hazardous substances, such as chemical residues and toxins, in agricultural food products. This review concentrates on the latest agro-food safety inspection techniques and methodologies constructed with the assistance of new hybrid micro/nanoentities, such as molecular imprinting polymers integrated with quantum dots (MIPs@QDs), molecular imprinting polymers integrated with upconversion luminescent nanoparticles (MIPs@UCNPs), upconversion luminescent nanoparticles combined with metal-organic frameworks (UCNPs@MOFs), magnetic metal-organic frameworks (MOFs@Fe₃O₄), magnetic covalent-organic frameworks (Fe₃O₄@COFs), covalent-organic frameworks doped with quantum dots (COFs@QDs), nanobody-involved immunoassay for fast inspection, etc. The presented summary and discussion favor a relevant outlook for further integrating various disciplines, like material science, nanotechnology, and analytical methodology, for addressing new challenges that emerge in agro-food research fields.

An out of box thinking: the changes of iron-porphyrin during meat processing and gastrointestinal tract and some methods for reducing its potential health hazard

Iron-porphyrin is a very important substance in organisms, especially in animals. It is not only the source of iron in human body, but is also the catalytic center of many reactions. Previous studies suggested that adequate intake of iron was important for the health of human, especially for children and pregnant women. However, associated diseases caused by iron over-intake and excessive meat consumption suggested its potential harmfulness for human health. During meat processing, Iron-porphyrin will cause the oxidation of proteins and fatty acids. In the gastrointestinal tract, iron-porphyrin can induce the production of malondialdehyde, fats oxidation, and indirectly cause oxidation of amino acids and nitrates etc. Iron-porphyrin enters the intestinal tract and disturbs the balance of intestinal flora. Finally, some common measures for inhibiting its activity are introduced, including the use of chelating agent, antioxidants, competitive inhibitor, etc., as well as give the hypothesis that sodium chloride increases the catalytic activity of iron-porphyrin. The purpose of this review is to present an overview of current knowledge about the changes of iron-porphyrin in the whole technico- and gastrointesto- processing axis and to provide ideas for further research in meat nutrition.

Identification of novel antioxidant peptide from porcine plasma hydrolysate and its effect in in vitro digestion/HepG2 cells model

A novel antioxidant peptide EDEQKFWGK from porcine plasma hydrolysate (PPH) was separated by chromatography, HPLC, and identified by LC-MS/MS. Results showed that EDEQKFWGK had better antioxidant ability (Hydroxyl RAS 32.19%, ABTS RAS 92.93% and DPPH RAS 26.76%) compared with glutathione (30.11%, 82.01%, 26.44%) due to the presence of hydrophobic, aromatic acids (F, W) and acidic amino acids (E, D), decreasing ROS by providing hydrogen atom and chelating metal ions. Furthermore, the antioxidant properties of synthetic EDEQKFWGK still significant despite in vitro digestion because of the production of smaller active peptide. Additionally, it could increase SOD, CAT, GSH-Px to resist oxidative damage in HepG2 cells by inhibiting ROS (O₂ ^- , OH·), forming complexes to prevent OH· from destroying DNA and binding to ARE to promote antioxidase expression. Thereby, the novel peptide EDEQKFWGK from porcine plasma had much stable antioxidant properties and hade great potential in formulating functional foods. PRACTICAL APPLICATIONS: This research isolated a novel antioxidant peptide. Moreover, the antioxidant effects of peptide were confirmed under the in vitro digestion model and oxidative damage HepG2 cells model. The results showed the antioxidant peptide could play better effect after digestion and protect the cells from oxidative damage. These data could expand the sequence data of antioxidant peptides and promote the high-value utilization of PPH.

New peptides with immunomodulatory activity identified from rice proteins through peptidomic and in silico analysis

The new food-derived bio-functional peptides are urgently needed globally, but the separation and purification process for obtaining the immunopeptides from food is low efficiency and highly time-consuming. In the present study, rice proteins were extracted and identified by using liquid chromatography/tandem mass spectrometry (LC-MS/MS). Furthermore, a strategy combining immuno-prediction and in silico simulation was used to screen for peptides showing immunomodulatory activity, including inhibition of the release of nitric oxide, tumor necrosis factor-α, and the interleukins IL-6 and IL-1β in lipopolysaccharide-induced RAW264.7 mouse macrophages. This LC-MS/MS identification and immuno-prediction method may provide insights for the potential identification of more food-derived immunopeptides.

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.

Three-dimensional assembly and disassembly of Fe3O4-decorated porous carbon nanocomposite with enhanced transversal relaxation for magnetic resonance sensing of bisphenol A

The design and construction of a novel magnetic resonance sensor (MRS) is presented for bisphenol A (BPA) detection. The MRS has been built based on the core component of magnetic Fe₃O₄ nanoparticles (~ 40 nm), which were uniformly distributed in nanoporous carbon (abbreviated as Fe₃O₄@NPC). The synthesis was derived from the calcination of the metal organic framework (MOF) precursor of Fe-MIL-101 at high temperature. Fe₃O₄@NPC was confirmed with enhanced transversal relaxation with r₂ value of 118.2 mM^-1 s^-1, which was around 1.7 times higher than that of the naked Fe₃O₄ nanoparticle. This enhancement is attributed to the excellent proton transverse relaxation rate of Fe₃O₄@NPC caused by the reduced self-diffusion coefficient of water molecules in the vicinity of Fe₃O₄ nanoparticles in the nanoporous carbon. BPA antibody (Ab) and antigen (Ag)-ovalbumin (OVA) were immobilized onto the Fe₃O₄@NPC to form Ab-Fe₃O₄@NPC and Ag-Fe₃O₄@NPC, respectively. These two composites can cause the three-dimensional assembly of Fe₃O₄@NPC via immunological recognition. The presence of BPA can compete with antigen-OVA to combine with Ab-Fe₃O₄@NPC, thereby breaking the assembly process (disassembly). The difference in the change of the T₂ value before and after adding BPA can thus be used to monitor BPA. The proposed MRS not only revealed a wide linear range of BPA concentration from 0.05 to 50 ng mL^-1 with an extremely low detection limit of 0.012 ng mL^-1 (S/N = 3), but also displayed high selectivity towards matrix interferences. The recoveries of BPA ranged from 95.6 to 108.4% for spiked tea π, and 93.4 to 104.7% for spiked canned oranges samples, respectively, and the RSD (n = 3) was less than 4.4% for 3 successive assays. The versatility of Fe₃O₄@NPC with customized relaxation responses provides the possibility for the adaptation of magnetic resonance platforms for food safety development. The magnetic Fe3O4 nanoparticles are uniformly dispersed in the nanoporous carbon (Fe3O4@NPC), which derived from the calcinating of the metal organic framework (MOF) precursor of Fe-MIL-101. And the magnetic Fe₃O₄@NPCs are adopted for the construction of magnetic resonance sensor (MRS) for bisphenol A (BPA) detection.

Cation exchange in a fluorescent zinc-based metal–organic framework for cadmium ion detection

A Zn metal–organic framework with a large aperture shows remarkable fluorescence characteristics for the detection of cadmium ions in aqueous solution and can adsorb CO2 and O2 selectively.

Metal Organic Frame-Upconverting Nanoparticle Assemblies for the FRET Based Sensor Detection of Bisphenol A in High-Salt Foods

To resolve the occurrence of unfulfillable detection in high-salts foods, we used fluorescence resonant energy transfer (FRET) sensors based on nanoparticle upconversion. In this study, we developed a novel FRET sensor for the detection of bisphenol A (BPA) in high-salt foods. We based this approach on the assembly of aptamer modified upconversion nanoparticles (DNA1-UCNPs) and complementary DNA modified metal organic frames (DNA2-MOFs), which possessed corresponding wavelength absorption. Targeting BPA signal transduction was performed using the BPA aptamer, via competitive recognition between the BPA analyte and complementary DNA sequences in a high-salt solution. Sensor adaption in high-salt samples was attributed to functional hydrophilic groups, modified in the MOFs, and the enhanced colloidal stability of these MOFs. The MOF-UCNP assembly displayed considerable analytical performance in terms of BPA detection, with a linear range of 0.1-100 nM, and a limit of detection (LOD) of 0.02 nM, in a 340 mM NaCl food sample (the energy drink, Gatorade). Thus, this method provides a solid basis for small molecules detection in high-salt foods.

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.