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

A Review of Recent Developments in Biopolymer Nano-Based Drug Delivery Systems with Antioxidative Properties: Insights into the Last Five Years

In recent years, biopolymer-based nano-drug delivery systems with antioxidative properties have gained significant attention in the field of pharmaceutical research. These systems offer promising strategies for targeted and controlled drug delivery while also providing antioxidant effects that can mitigate oxidative stress-related diseases. Generally, the healthcare landscape is constantly evolving, necessitating the continual development of innovative therapeutic approaches and drug delivery systems (DDSs). DDSs play a pivotal role in enhancing treatment efficacy, minimizing adverse effects, and optimizing patient compliance. Among these, nanotechnology-driven delivery approaches have garnered significant attention due to their unique properties, such as improved solubility, controlled release, and targeted delivery. Nanomaterials, including nanoparticles, nanocapsules, nanotubes, etc., offer versatile platforms for drug delivery and tissue engineering applications. Additionally, biopolymer-based DDSs hold immense promise, leveraging natural or synthetic biopolymers to encapsulate drugs and enable targeted and controlled release. These systems offer numerous advantages, including biocompatibility, biodegradability, and low immunogenicity. The utilization of polysaccharides, polynucleotides, proteins, and polyesters as biopolymer matrices further enhances the versatility and applicability of DDSs. Moreover, substances with antioxidative properties have emerged as key players in combating oxidative stress-related diseases, offering protection against cellular damage and chronic illnesses. The development of biopolymer-based nanoformulations with antioxidative properties represents a burgeoning research area, with a substantial increase in publications in recent years. This review provides a comprehensive overview of the recent developments within this area over the past five years. It discusses various biopolymer materials, fabrication techniques, stabilizers, factors influencing degradation, and drug release. Additionally, it highlights emerging trends, challenges, and prospects in this rapidly evolving field.

Advances in Research on the Activity Evaluation, Mechanism and Structure-Activity Relationships of Natural Antioxidant Peptides

Antioxidant peptides are a class of biologically active peptides with low molecular weights and stable antioxidant properties that are isolated from proteins. In this review, the progress in research on the activity evaluation, action mechanism, and structure-activity relationships of natural antioxidant peptides are summarized. The methods used to evaluate antioxidant activity are mainly classified into three categories: in vitro chemical, in vitro cellular, and in vivo animal methods. Also, the biological effects produced by these three methods are listed: the scavenging of free radicals, chelation of metal ions, inhibition of lipid peroxidation, inhibition of oxidative enzyme activities, and activation of antioxidant enzymes and non-enzymatic systems. The antioxidant effects of natural peptides primarily consist of the regulation of redox signaling pathways, which includes activation of the Nrf2 pathway and the inhibition of the NF-κB pathway. The structure-activity relationships of the antioxidant peptides are investigated, including the effects of peptide molecular weight, amino acid composition and sequence, and secondary structure on antioxidant activity. In addition, four computer-assisted methods (molecular docking, molecular dynamics simulation, quantum chemical calculations, and the determination of quantitative structure-activity relationships) for analyzing the structure-activity effects of natural peptides are summarized. Thus, this review lays a theoretical foundation for the development of new antioxidants, nutraceuticals, and cosmetics.

Bio-functional and prebiotics properties of products based on whole grain sorghum fermented with lactic acid bacteria

BACKGROUND

Products fermented with lactic acid bacteria based on whole grain flours of red or white sorghum (Sorghum bicolor (L.) Moench) added with malted sorghum flour, or with skim milk (SM) were developed. Composition, protein amino acid profile, total acidity, pH, prebiotic potential, and bio-functional properties after simulation of gastrointestinal digestion were evaluated.

RESULTS

In all cases, a pH of 4.5 was obtained in approximately 4.5 h. The products added with SM presented higher acidity. Products made only with sorghum presented higher total dietary fiber, but lower protein content than products with added SM, the last ones having higher lysine content. All products exhibited prebiotic potential, white sorghum being a better ingredient to promote the growth of probiotic bacteria. The addition of malted sorghum or SM significantly increased the bio-functional properties of the products: the sorghum fermented products added with SM presented the highest antioxidant (ABTS•+ inhibition, 4.7 ± 0.2 mM Trolox), antihypertensive (Angiotensin converting enzyme-I inhibition, 57.3 ± 0.5%) and antidiabetogenic (dipeptidyl-peptidase IV inhibition, 31.3 ± 2.1%) activities, while the products added with malted sorghum presented the highest antioxidant (reducing power, 1.6 ± 0.1 mg ascorbic acid equivalent/mL) and antidiabetogenic (α-amylase inhibition, 38.1 ± 0.9%) activities.

CONCLUSION

The fermented whole grain sorghum-based products could be commercially exploited by the food industry to expand the offer of the three high-growth markets: gluten-free products, plant-based products (products without SM), and functional foods. © 2023 Society of Chemical Industry.

Identification of the Bioavailable Peptidome of Chia Protein Hydrolysate and the In Silico Evaluation of Its Antioxidant and ACE Inhibitory Potential

The incorporation of novel, functional, and sustainable foods in human diets is increasing because of their beneficial effects and environmental-friendly nature. Chia (Salvia hispanica L.) has proved to be a suitable source of bioactive peptides via enzymatic hydrolysis. These peptides could be responsible for modulating several physiological processes if able to reach the target organ. The bioavailable peptides contained in a hydrolysate obtained with Alcalase, as functional foods, were identified using a transwell system with Caco-2 cell culture as the absorption model. Furthermore, 20 unique peptides with a molecular weight lower than 1000 Da and the higher statistical significance of the peptide-precursor spectrum match (-10 log P) were assessed by in silico tools to suggest which peptides could be those exerting the demonstrated bioactivity. From the characterized peptides, considering the molecular features and the results obtained, the peptides AGDAHWTY, VDAHPIKAM, PNYHPNPR, and ALPPGAVHW are anticipated to be contributing to the antioxidant and/or ACE inhibitor activity of the chia 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.

Antibacterial activity of a polysaccharide isolated from Artemisia argyi leaf against Staphylococcus aureus and mechanism investigation

Abuse of antibiotics has led to excessive amounts of antibiotic residues in food and environment, thus enhancing pathogenic bacterium resistance and threatening human health. Therefore, searching and developing safe and green antibiotic alternatives are necessary. In this study, an Artemisia argyi leaf polysaccharide (AALP) fraction was extracted and analyzed. Chemical composition analysis showed that the carbohydrate, uronic acid, protein, and polyphenol content in AALP were 68.3 % ± 4.13 %, 9.4 % ± 0.86 %, 1.79 % ± 0.27 %, and 0.16 % ± 0.035 %, respectively. Chromatographic results suggested that AALP contained rhamnose, arabinose, glucosamine, galactose, glucose, xylose, mannose, galacturonic acid, and glucuronic acid in a molar ratio of 9.26, 1.35, 1.18, 3.04, 48.51, 2.33, 31.26, 3.93, and 9.08; the weight average molecular weight, number average molecular weight, and polydispersity of AALP were 5.41 kDa, 4.63 kDa, and 1.168, respectively. Fourier transform infrared spectroscopy indicated that AALP constituted the polysaccharide-specific groups of CH, CO, and OH. Meanwhile, AALP showed a dose-dependent inhibitory effect on Staphylococcus aureus in the inhibition zone assay, and the minimal inhibitory concentration was 1.25 mg/mL. Furthermore, AALP disrupted the cell wall, depolarized the inner membrane potential, and inhibited the activities of succinate dehydrogenase and malate dehydrogenase in S. aureus.

From microbes to molecules: a review of microbial-driven antioxidant peptide generation

Oxidative stress, arising from excess reactive oxygen species (ROS) or insufficient antioxidant defenses, can damage cellular components, such as lipids, proteins, and nucleic acids, resulting in cellular dysfunction. The relationship between oxidative stress and various health disorders has prompted investigations into potent antioxidants that counteract ROS's detrimental impacts. In this context, antioxidant peptides, composed of two to twenty amino acids, have emerged as a unique group of antioxidants and have found applications in food, nutraceuticals, and pharmaceuticals. Antioxidant peptides are sourced from natural ingredients, mainly proteins derived from foods like milk, eggs, meat, fish, and plants. These peptides can be freed from their precursor proteins through enzymatic hydrolysis, fermentation, or gastrointestinal digestion. Previously published studies focused on the origin and production methods of antioxidant peptides, describing their structure-activity relationship and the mechanisms of food-derived antioxidant peptides. Yet, the role of microorganisms hasn't been sufficiently explored, even though the production of antioxidant peptides frequently employs a variety of microorganisms, such as bacteria, fungi, and yeasts, which are recognized for producing specific proteases. This review aims to provide a comprehensive overview of microorganisms and their proteases participating in enzymatic hydrolysis and microbial fermentation to produce antioxidant peptides. This review also covers endogenous peptides originating from microorganisms. The information obtained from this review might guide the discovery of novel organisms adept at generating antioxidant peptides.

Exploring novel ANGICon-EIPs through ameliorated peptidomics techniques: Can deep learning strategies as a core breakthrough in peptide structure and function prediction?

Dairy-derived angiotensin-I-converting enzyme inhibitory peptides (ANGICon-EIPs) have been regarded as a relatively safe supplementary diet-therapy strategy for individuals with hypertension, and short-chain peptides may have more relevant antihypertensive benefits due to their direct intestinal absorption. Our previous explorations have confirmed that endogenous goat milk short-chain peptides are also an essential source of ANGICon-EIPs. Nonetheless, there are limited explorations on endogenous ANGICon-EIPs owing to the limitations of the extraction and enrichment of endogenous peptides, currently. This review outlined ameliorated pre-treatment strategies, data acquisition methods, and tools for the prediction of peptide structure and function, aiming to provide creative ideas for discovering novel ANGICon-EIPs. Currently, deep learning-based peptide structure and function prediction algorithms have achieved significant advancements. The convolutional neural network (CNN) and peptide sequence-based multi-label deep learning approach for determining the multi-functionalities of bioactive peptides (MLBP) can predict multiple peptide functions with absolute true value and accuracy of 0.699 and 0.708, respectively. Utilizing peptide sequence input, torsion angles, and inter-residue distance to train neural networks, APPTEST predicted the average backbone root mean square deviation (RMSD) value of peptide (5-40 aa) structures as low as 1.96 Å. Overall, with the exploration of more neural network architectures, deep learning could be considered a critical research tool to reduce the cost and improve the efficiency of identifying novel endogenous ANGICon-EIPs.

Preparation, Characterization, and Antioxidant Properties of Selenium-Enriched Tea Peptides

The research on the activity of selenium (Se)-enriched agricultural products is receiving increasing attention since Se was recognized for its antioxidant activities and for its enhancement of immunity in trace elements. In this study, antioxidant Se-containing peptides, namely, Se-TAPepI-1 and Se-TAPepI-2, were optimally separated and prepared from Se-enriched tea protein hydrolysates by ultrafiltration and Sephadex G-25 purification, and subsequently, their physicochemical properties, oligopeptide sequence, and potential antioxidant mechanism were analyzed. Through the optimization of enzymatic hydrolysis conditions, the Se-enriched tea protein hydrolyzed by papain exhibited a better free radical scavenging activity. After separation and purification of hydrolysates, the two peptide fractions obtained showed significant differences in selenium content, amino acid composition, apparent morphology, peptide sequence, and free radical scavenging activity. Therein, two peptides from Se-TAPepI-1 included LPMFG (563.27 Da) and YPQSFIR (909.47 Da), and three peptides from Se-TAPepI-2 included GVNVPYK (775.42 Da), KGGPGG (552.24 Da), and GDEPPIVK (853.45 Da). Se-TAPepI-1 and Se-TAPepI-2 could ameliorate the cell peroxidation damage and inflammation by regulating NRF2/ARE pathway expression. Comparably, Se-TAPepI-1 showed a better regulatory effect than Se-TAPepI-2 due to their higher Se content, typical amino acid composition and sequence, higher surface roughness, and a looser arrangement in their apparent morphology. These results expanded the functional activities of tea peptide and provided the theoretical basis for the development of Se-containing peptides from Se-enriched tea as a potential natural source of antioxidant dietary supplements.

Current state of insect proteins: extraction technologies, bioactive peptides and allergenicity of edible insect proteins

This review aims to provide an updated overview of edible insect proteins and the bioactivity of insect-derived peptides. The essential amino acid content of edible insects is compared with well-known protein sources to demonstrate that edible insects have the potential to cover the protein quality requirements for different groups of the population. Then the current methodologies for insect protein extraction are summarized including a comparison of the protein extraction yield and the final protein content of the resulting products for each method. Furthermore, in order to improve our understanding of insect proteins, their functional properties (such as solubility, foaming capacity, emulsifying, gelation, water holding capacity and oil holding capacity) are discussed. Bioactive peptides can be released according to various enzymatic hydrolysis protocols. In this context, the bioactive properties of insect peptides (antihypertensive, antidiabetic, antioxidant and anti-inflammatory properties) have been discussed. However, the allergens present in insect proteins are still a major concern and an unsolved issue for insect-based product consumption; thus, an analysis of cross reactivity and the different methods available to reduce allergenicity are proposed. Diverse studies of insect protein hydrolysates/peptides have been ultimately promoting the utilization of insect proteins for future perspectives and the emerging processing technologies to enhance the wider utilization of insect proteins for different purposes.

Novel and efficient techniques in the discovery of antioxidant peptides

As a research hotspot in food science and nutrition, antioxidant peptides can function by scavenging free radicals, inhibiting peroxides, and chelating metal ions. Therefore, how to efficiently discover and screen antioxidant peptides has become a key issue in research and production. Traditional discovery methods are time-consuming and costly, but also challenging to resolve the quantitative structure-activity relationship of antioxidant peptides. Several novel techniques, including artificial intelligence, molecular docking, bioinformatics, quantum chemistry, phage display, switchSENSE, surface plasmon resonance, and fluorescence polarization, are emerging rapidly as solutions. These techniques possess efficient capability for the discovery of antioxidant peptides, even with the potential for high-throughput screening. In addition, the quantitative structure-activity relationship can be resolved. Notably, combining these novel techniques can overcome the drawbacks of a single one, thus improving efficiency and expanding the discovery horizon. This review has summarized eight novel and efficient techniques for discovering antioxidant peptides and the combination of techniques. This review aims to provide scientific evidence and perspectives for antioxidant peptide research.

Toward the high-efficient utilization of poultry blood: Insights into functionality, bioactivity and functional components

A large amount of poultry blood is annually generated, and currently underutilized or largely disposed of as waste, resulting in environmental pollution and waste of protein resources. As one of the main by-products during the poultry slaughter process, the produced poultry blood can serve as a promising food ingredient due to its excellent functional properties and abundant source of essential amino acids, bioactive peptides and functional components. This work provides a comprehensive summary of recent research progress in the composition, functional and bioactive properties, as well as the functional components of poultry blood. Furthermore, the main preparation methods of poultry blood-derived peptides and their bioactivities were reviewed. In addition, their potential applications in the food industry were discussed. Overall, poultry blood is characterized by excellent functionalities, including solubility, gelation, foaming, and emulsifying properties. The major preparation methods for poultry blood-derived peptides include enzymatic hydrolysis, ultrasound-assisted enzymatic methods, macroporous adsorbent resins, and subcritical water hydrolysis. Poultry blood-derived peptides exhibit diverse bioactivities. Their metallic off-flavors and bitterness can be improved by exopeptidase treatment, Maillard reaction, and plastein reaction. In addition, poultry blood is also abundant in functional components such as hemoglobin, superoxide dismutase, immunoglobulin, and thrombin.

From In Silico to a Cellular Model: Molecular Docking Approach to Evaluate Antioxidant Bioactive Peptides

The increasing need to counteract the redox imbalance in chronic diseases leads to focusing research on compounds with antioxidant activity. Among natural molecules with health-promoting effects on many body functions, bioactive peptides are gaining interest. They are protein fragments of 2–20 amino acids that can be released by various mechanisms, such as gastrointestinal digestion, food processing and microbial fermentation. Recent studies report the effects of bioactive peptides in the cellular environment, and there is evidence that these compounds can exert their action by modulating specific pathways. This review focuses on the newest approaches to the structure–function correlation of the antioxidant bioactive peptides, considering their molecular mechanism, by evaluating the activation of specific signaling pathways that are linked to antioxidant systems. The correlation between the results of in silico molecular docking analysis and the effects in a cellular model was highlighted. This knowledge is fundamental in order to propose the use of bioactive peptides as ingredients in functional foods or nutraceuticals.

Eighteen Novel Bioactive Peptides from Monkfish (Lophius litulon) Swim Bladders: Production, Identification, Antioxidant Activity, and Stability

In the study, papain was chosen from five proteases to hydrolyze proteins of monkfish swim bladders for effectively utilizing monkfish (Lophius litulon) processing byproducts, and the hydrolysis conditions of papain were optimized as hydrolysis temperature of 65 °C, pH 7.5, enzyme dose 2.5% and time 5 h using single-factor and orthogonal experiments. Eighteen peptides were purified from the swim bladder hydrolysate of monkfish by ultrafiltration and gel permeation chromatography methods and identified as YDYD, QDYD, AGPAS, GPGPHGPSGP, GPK, HRE, GRW, ARW, GPTE, DDGGK, IGPAS, AKPAT, YPAGP, DPT, FPGPT, GPGPT, GPT and DPAGP, respectively. Among eighteen peptides, GRW and ARW showed significant DPPH· scavenging activities with EC₅₀ values of 1.053 ± 0.003 and 0.773 ± 0.003 mg/mL, respectively; YDYD, QDYD, GRW, ARW and YPAGP revealed significantly HO· scavenging activities with EC₅₀ values of 0.150 ± 0.060, 0.177 ± 0.035, 0.201 ± 0.013, 0.183 ± 0.0016 and 0.190 ± 0.010 mg/mL, respectively; YDYD, QDYD, ARW, DDGGK and YPAGP have significantly O2-· scavenging capability with EC₅₀ values of 0.126 ± 0.0005, 0.112 ± 0.0028, 0.127 ± 0.0002, 0.128 ± 0.0018 and 0.107 ± 0.0002 mg/mL, respectively; and YDYD, QDYD and YPAGP showed strong ABTS⁺· scavenging ability with EC₅₀ values of 3.197 ± 0.036, 2.337 ± 0.016 and 3.839 ± 0.102 mg/mL, respectively. YDYD, ARW and DDGGK displayed the remarkable ability of lipid peroxidation inhibition and Ferric-reducing antioxidant properties. Moreover, YDYD and ARW can protect Plasmid DNA and HepG2 cells against H₂O₂-induced oxidative stress. Furthermore, eighteen isolated peptides had high stability under temperatures ranging from 25-100 °C; YDYD, QDYD, GRW and ARW were more sensitive to alkali treatment, but DDGGK and YPAGP were more sensitive to acid treatment; and YDYD showed strong stability treated with simulated GI digestion. Therefore, the prepared antioxidant peptides, especially YDYD, QDYD, GRW, ARW, DDGGK and YPAGP from monkfish swim bladders could serve as functional components applied in health-promoting products because of their high-antioxidant functions.

Formation of Oxidative Compounds during Enzymatic Hydrolysis of Byproducts of the Seafood Industry

There is a significant potential to increase the sustainability of the fishing and aquaculture industries through the maximization of the processing of byproducts. Enzymatic hydrolysis provides an opportunity to valorize downstream fish industry byproducts for the production of protein hydrolysates (FPH) as a source of bioactive peptides (BAP) with health benefits. Deteriorative oxidative reactions may occur during the enzymatic hydrolysis of byproducts, influencing the safety or bioactivities of the end product. Lipid oxidation, autolysis mediated by endogenous enzymes in viscera, protein degradation, and formation of low-molecular-weight metabolites are the main reactions that are expected to occur during hydrolysis and need to be controlled. These depend on the freshness, proper handling, and the type of byproducts used. Viscera, frames, trimmings, and heads are the byproducts most available for enzymatic hydrolysis. They differ in their composition, and, thus, require standardization of both the hydrolysis procedures and the testing methods for each source. Hydrolysis conditions (e.g., enzyme type and concentration, temperature, and time) also have a significant role in producing FPH with specific structures, stability, and bioactivity. Protein hydrolysates with good safety and quality should have many applications in foods, nutraceuticals, and pharmaceuticals. This review discusses the oxidative reactions during the enzymatic hydrolysis of byproducts from different fish industry sectors and possible ways to reduce oxidation.