Sunflower seed-derived bioactive peptides show antioxidant and anti-inflammatory activity: From in silico simulation to the animal model

Screening, identification, and mechanism of novel antioxidant peptides in walnut meal under aerobic stress

Walnut (Juglans regia L.) meal, being the primary by-product of walnut oil processing, is rich in high-quality proteins and of significant potential for development and utilization. The study used multi-stage gradient purification, liquid-quantity chromatography, and computerized virtual screening to isolate and characterize antioxidant peptides from walnut meal. Active sites and mechanism actions of antioxidant peptides were examined using oxidative damage model of HepG2 cells. Five novel peptides exhibiting high antioxidant activity were identified, among which YR-10 significantly increased the cell viability of HepG2 oxidatively damaged cells to 20.64 %. Meanwhile, YR-10 significantly reduced the ROS content to 42.54 % and apoptosis level to 11.80 % in HepG2 oxidatively damaged cells. In addition, YR-10 competed with Nrf2 for Keap1 binding site, inhibited Keap1 (13.83 %) expression, and promoted Nrf2 (27.15 %), HO-1 (34.59 %), and SOD1 (42.67 %) expression, which ultimately activated the Keap1/Nrf2/HO-1 pathway and alleviated oxidative damage.

Identification of Ni2+-binding peptides in sunflower meal protein hydrolysate for deeper understanding of peptide-metal interactions

Sunflower (Helianthus annus L.) is one of the most important oil crops in the world. Once oil extracted, sunflower meal by-product could offer a potential alternative for various food applications due to its high protein content. Derived from food protein hydrolysates, metal-binding peptides have attracted attention as bioactive compounds to prevent metal-induced oxidation and diseases. This study aimed to investigate the Ni2+-binding ability of sunflower meal protein hydrolysates and ten peptides theoretically present in sunflower proteins using IMAC, switchSENSE®, UV-vis and CD techniques. Single and sequential enzymatic treatments were applied to produce hydrolysates using Protamex® (Prot) and Protamex followed by Flavourzyme® (Prot+Flav), respectively. MS/MS analysis of enriched Ni2+-binding peptides fractions revealed different composition of His-containing peptides among hydrolysates; however, similar to the His-containing pure peptides, the Ni2+-binding ability of all the hydrolysates was almost identical in IMAC. On the contrary, switchSENSE® studies indicated that the Ni2+-binding ability of sunflower peptides does not depend only on the presence of His residues, but also on their position along the polypeptide chain and the presence of proline, suggesting that Prot hydrolysates exhibited the highest Ni2+-binding ability. UV-vis and CD data confirmed that sunflower peptides bound onto Ni2+ through nitrogen atoms from imidazole sidechain of His residues, deprotonated amide bonds and N-terminal amino group, indicating square-planar and also octahedral geometries in the formed complexes. Finally, His-containing peptides without proline could offer a suitable strategy to design metal-binding peptides from sunflower meal by-product, with the most promising motifs being LLHVT and WLH.

Antioxidant Peptides from Tiger Nut (Cyperus esculentus L.): Chemical Analysis and Cytoprotective Functions on HepG2 and Caco-2 Cells

Tiger nuts were enzymatically hydrolyzed by Alcalase and then separated and purified by ultrafiltration classification and Sephadex G-15 fractionation to obtain tiger nut peptides. Their chemical antioxidant activities and cytoprotective functions on HepG2 and Caco-2 cells were systematically evaluated in this study. The tiger nut peptides (TNP) were found to perform excellent antioxidant activity supported by their chemical and cell antioxidant behaviors, amino acid composition, and morphological observation. Higher 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity (DPPH• RSA, 64.05-124.07%) and ferric ion-reducing antioxidant power (FRAP, 0.17-1.78 μmol/mL) were observed in the TNP with more hydrophobic amino acids (41.77 ± 1.36 g/100 g) compared with traditional soybean and peanut peptides. Furthermore, the peptides from tiger nut (TNP, TNP-4, T1, T2, T3) could effectively protect H2O2-induced HepG2 and Caco-2 cells from oxidative damage by enhancing endogenous antioxidant enzyme activities and reducing oxidative stress levels, especially the T3 peptides purified from the fraction less than 1 kDa molecular weight. The catalase, superoxide dismutase, and glutathione peroxidase activities significantly increased, and the contents of intracellular reactive oxygen species and malondialdehyde decreased. This study highlights the potential of the peptides from tiger nuts as antioxidant ingredients for food applications.

Bioactive peptides from food waste: New innovative bio-nanocomplexes to enhance cellular uptake and biological effects

Mastitis is the most important bovine disease, causing dramatic economic losses to the dairy industry, worldwide. This study explores the valorization of whey from cows affected by mastitis, through a novel separation approach. Surface Active Maghemite Nanoparticles (SAMNs) were used as magnetic baits to selectively bind bioactive peptides with potential health benefits. Advanced techniques such as HPLC and LC-MS/MS highlighted SAMN capability of isolating a restricted group of peptides, drastically diverging from the control profile (Solid Phase Extraction, SPE) and characterized by a peculiar acidic residue distribution. Most importantly, both magnetically purified and nano-immobilized peptides (SAMN@peptides) showed protective activity against oxidative stress and inflammation, when tested on Caco-2 cells; with SAMN@peptides being associated with the strongest biological effect. SAMNs exhibited excellent characteristics, they are environmentally sustainable, and their synthesis is cost-effective prompting at a scalable and selective tool for capturing bioactive peptides, with potential applications in functional foods and nutraceuticals.

Transforming plant-based waste and by-products into valuable products using various "Food Industry 4.0" enabling technologies: A literature review

The last several years have seen unprecedented strain on food systems as a result of pandemics, climate change, population growth, and urbanization. Thus, academic and scientific communities now view global food security as a critical issue. However, food loss and waste are a major challenge when adopting food security and sustainability strategies, since a large proportion of food is lost or wasted along the food supply chain. In order to use resources efficiently and enhance food security and sustainability, food waste and by-products must be reduced and properly valorized. Plant-based food production generates various by-products which are generally rich in nutrients and bioactive compounds. Emerging technologies have been effectively employed to extract these valuable compounds with health benefits. Recently, Industry 4.0 technologies such as artificial intelligence, the Internet of Things, blockchain, robotics, smart sensors, 3D printing, and digital twins have a great deal of potential for waste reduction and by-products valorization in food industry. Reducing food waste not only benefits the environment, but also reduces greenhouse gas emissions and thus contributes to sustainable resource management. This review provides up-to-date information on the potential of Industry 4.0 for converting plant-based waste and by-products into valuable products. Recent studies showed that innovations in Industry 4.0 provide attractive opportunities to increase the effectiveness of manufacturing operations and improve food quality, safety and traceability. By leveraging Food Industry 4.0, companies can transform plant-based waste and by-products into valuable products and contribute to a more sustainable and efficient food production system.

Anti-inflammatory potential of mycoprotein peptides obtained from fermentation of Schizophyllum commune DS1 with young apples

Fermenting edible filamentous fungi with food industry by-products, such as young apples, shows promise for producing mycoproteins and functional peptides. This study aimed to evaluate the production of mycoprotein by fermenting different edible-grade filamentous fungi using young apples as a substrate. Schizophyllum commune DS1 (DS1) demonstrated significant potential for generating mycoprotein, yielding 33.56 ± 0.82 %. From the hydrolysis of DS1 mycoprotein, three polypeptides were identified with the capacity of inhibiting nitric oxide synthase (iNOS): DNIQGITKPAIR (DR12), SDNAFGGR (SR8), and ASDPSGF (AF7). Computational analysis, including bioinformatics and molecular docking, indicated their high affinity for inhibiting iNOS, with binding energies of -452.8157 kcal/mol, -388.0222 kcal/mol, and -323.8843 kcal/mol, respectively. This binding was facilitated through various interactions such as electrostatic forces, π-π interactions, hydrogen bonds, and non-covalent interactions, resulting in potential anti-inflammatory properties. Furthermore, cell experiments using RAW264.7 macrophages demonstrated that these peptides effectively suppressed nitric oxide production in a dose-dependent manner. Additionally, they reduced the production of inflammatory cytokines, such as interleukin-6 (IL-6), interleukin-1β (IL-1β), inducible iNOS, and cell apoptosis. In conclusion, this study presents a novel approach for developing plant-based mycoproteins and a new source for discovering food-derived bioactive peptides.

Fermented blend from sunflower seed press-cake and bovine sweet whey: Protein breakdown during in vitro gastrointestinal digestion

Sustainable food production implements circular economic system, valuing side streams and minimizing waste. This study was aimed to develop a new food by fermenting a blend of dehulled sunflower seed protein powder (SSPP) and reconstituted bovine sweet whey powder (RSWP). Blends were inoculated with Lactococcus lactis B12 alone or in association with Saccharomyces cerevisiae L12, and fermentation proceeded until reaching pH 4.8. After in vitro static gastrointestinal digestion, RSWP and SSPP proteins were highly proteolyzed and the soluble nitrogen content was 69-71% of total nitrogen. In digests, 42-75 unique peptides were identified, and most of them weighed 500-1000 Da. Free amino acids accounted for 202-228 mg/g protein in digests. Few bioactive peptides derived from RSWP were identified. These findings demonstrated strong degradability of RSWP and SSPP proteins during digestion and shed light on nutritional properties exploitable for food applications of the developed fermented blend.

By-Products Valorization: Peptide Fractions from Milk Permeate Exert Antioxidant Activity in Cellular and In Vivo Models

The discarding of agri-food by-products is a stringent problem due to their high environmental impact. Recovery strategies can lead to a reduction of waste and result in new applications. Agri-food waste represents a source of bioactive molecules, which could promote health benefits. The primary goal of this research has been the assessment of the antioxidant activity of milk permeate, a dairy farm by-product, and the isolation and identification of peptide fractions endowed with antioxidant activity. The chromatographic extraction of the peptide fractions was carried out, and the peptides were identified by mass spectrometry. The fractions showed radical scavenging activity in vitro. Moreover, the results in the Caco-2 cell model demonstrated that the peptide fractions were able to protect from oxidative stress by stimulating the Keap1/Nrf2 antioxidant signaling pathway, increasing the transcription of antioxidant enzymes. In addition, the bioactive peptides can affect cellular metabolism, increasing mitochondrial respiration. The action of the peptide fractions was also assessed in vivo on a zebrafish model and resulted in the protection of the whole organism from the adverse effects of acute cold stress, highlighting their strong capability to protect from an oxidative insult. Altogether, the results unveil novel recovery strategies for food by-products as sources of antioxidant bioactive peptides that might be utilized for the development of functional foods.

Antioxidant Function and Application of Plant-Derived Peptides

With the development of society and the improvement of people's health consciousness, the demand for antioxidants is increasing. As a natural antioxidant with no toxic side effects, antioxidant peptides are widely used in food, cosmetics, medicine, and other fields because of their strong antioxidant capacity and easy absorption by the human body. Plant-derived antioxidant peptides have attracted more attention than animal-derived antioxidant peptides because plants are more diverse than animals and produce a large number of protein-rich by-products during the processing of their products, which are the main source of antioxidant peptides. In this review, we summarize the source, structure and activity, other biological functions, mechanism of action, and comprehensive applications of plant antioxidant peptides, and look forward to their future development trends, which will provide a reference for further research and development of plant antioxidant peptides.

Screening and Exploring the Application of the Multifunctional Antioxidant Peptides MSWLC and TSWLC

In this study, an antioxidant pentapeptide library is created based on antioxidant characteristics. The peptides are then purified and separated using liquid chromatography/mass spectrometry (LC/MS) and time-of-flight mass spectrometry (TOF). Chemical evaluations identify four peptides with excellent antioxidant activity. The four peptides undergo biocompatibility testing with L-929, NIH 3T3, and Hep-G2 cells. A model of hydrogen peroxide-induced cellular damage in G2 cells shows the peptides' protective and reparative effects against oxidative damage. Two peptides, MSWLC and TSWLC, which perform best overall, are chosen for further analysis. To explore the peptides' potential multifunctionality, acute liver inflammation, keratitis, and aging models are established in mice. MSWLC and TSWLC demonstrate anti-inflammatory and anti-aging properties. An antioxidant emulsion prepared by emulsification is found to be non-irritant in a mouse skin irritation test. In a mouse model exposed to ultraviolet radiation, the sunscreen exhibits excellent UV protection and antioxidant effects. These peptides possess potent antioxidant properties and multifunctionality, indicating broad application potential.

Structurally manipulated antioxidant peptides derived from wheat bran: Preparation and identification

Bioactive peptide's development is facing two challenges in terms of its lower yield and limited understanding of structurally orientated functionality. Therefore, peptides were prepared from wheat bran via a cocktail enzyme for achieving a higher level of hydrophobic amino acids than traditional method. The obtained peptides exhibited great antioxidant activities against H2O2-induced oxidative stress in HepG2 cells. Among them, 91 bioactive peptides were selected through the virtual screening, and their N-terminal and C-terminal contained many hydrophobic amino acids. Then the peptides with capacity to interact with Keap1 were identified by in silico simulation, because Keap1 acts as a sensor of redox insults. The results revealed that peptides DLDW and DLGL demonstrated the highest binding affinities, and a bridge was formed between Asp of DLGL and Arg415 of Klech domain, contributing to interfering Keap1-Nrf2 interaction. These findings implied a potential application of wheat bran peptides as nutraceuticals and health-promoting ingredients.

Preparation, Isolation and Antioxidant Function of Peptides from a New Resource of Rumexpatientia L. ×Rumextianshanicus A. Los

Rumexpatientia L. ×Rumextianshanicus A. Los (RRL), known as "protein grass" in China, was recognized as a new food ingredient in 2021. However, the cultivation and product development of RRL are still at an early stage, and no peptide research has been reported. In this study, two novel antioxidant peptides, LKPPF and LPFRP, were purified and identified from RRL and applied to H2O2-induced HepG2 cells to investigate their antioxidant properties. It was shown that 121 peptides were identified by ultrafiltration, gel filtration chromatography, and LC-MS/MS, while computer simulation and molecular docking indicated that LKPPF and LPFRP may have strong antioxidant properties. Both peptides were not cytotoxic to HepG2 cells at low concentrations and promoted cell growth, which effectively reduced the production of intracellular ROS and MDA, and increased cell viability and the enzymatic activities of SOD, GSH-Px, and CAT. Therefore, LKPPF and LPFRP, two peptides, possess strong antioxidant activity, which provides a theoretical basis for their potential as food additives or functional food supplements, but still need to be further investigated through animal models as well as cellular pathways.