Purification, Identification, and Mechanistic Investigation of Novel Selenium-Enriched Antioxidant Peptides from Moringa oleifera Seeds

Identification, in silico selection, and mechanistic investigation of antioxidant peptides from corn gluten meal hydrolysate

Seven novel antioxidant peptides (AWF, LWQ, WIY, YLW, LAYW, LPWG, and LYFY) exhibiting a superior activity compared to trolox were identified through in silico screening. Among these, the four peptides (WIY, YLW, LAYW, and LYFY) displayed notably enhanced performance, with ABTS activity 2.58-3.26 times and ORAC activity 5.19-8.63 times higher than trolox. Quantum chemical calculations revealed that the phenolic hydroxyl group in tyrosine and the nitrogen-hydrogen bond in the indole ring of tryptophan serve as the critical sites for antioxidant activity. These findings likely account for the potent chemical antioxidant activity. The corn peptides also exerted a protective effect against AAPH-induced cytomorphologic changes in human erythrocytes by modulating the antioxidant system. Notably, LAYW exhibited the most pronounced cytoprotective effects, potentially due to its high content of hydrophobic amino acids.

Co-Immobilization of Alcalase/Dispase for Production of Selenium-Enriched Peptide from Cardamine violifolia

Enzymatically derived selenium-enriched peptides from Cardamine violifolia (CV) can serve as valuable selenium supplements. However, the industrial application of free enzyme is impeded by its limited stability and reusability. Herein, this study explores the application of co-immobilized enzymes (Alcalase and Dispase) on amino resin for hydrolyzing CV proteins to produce selenium-enriched peptides. The successful enzyme immobilization was confirmed through scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and Fourier-transform infrared spectroscopy (FTIR). Co-immobilized enzyme at a mass ratio of 5:1 (Alcalase/Dispase) exhibited the smallest pore size (7.065 nm) and highest activity (41 U/mg), resulting in a high degree of hydrolysis of CV protein (27.2%), which was obviously higher than the case of using free enzymes (20.7%) or immobilized Alcalase (25.8%). In addition, after a month of storage, the co-immobilized enzyme still retained a viability level of 41.93%, showing fairly good stability. Encouragingly, the selenium-enriched peptides from co-immobilized enzyme hydrolysis exhibited uniform distribution of selenium forms, complete amino acid fractions and homogeneous distribution of molecular weight, confirming the practicality of using co-immobilized enzymes for CV protein hydrolysis.

Hydroxyl group-induced enhancement of antioxidant activity of resveratrol over pterostilbene by binding to lactoferrin

The reduced antioxidant capacity of trans-resveratrol (Res) than the second generation of Res, namely pterostilbene (Pte), severely prohibits its in-depth intriguing radical-scavenging applications in food formulations. Herein, a unique chemical structure-dependent strategy was proposed to specifically enhance the radical scavenging activity of Res over Pte, relying on the two more hydroxyl groups on the A-benzene ring of Res, thus facilitating its binding with lactoferrin (LF) to form stable complexes through more hydrogen bonds. We prepared LF-Res and LF-Pte complexes, revealed their binding mechanisms by multispectral analysis and molecular docking/dynamics simulations, further evaluated their antioxidant properties via ABTS and DPPH assays and a model of inhibiting apple browning, eventually elucidated their structure-binding-property relationships. This contribution offers a new approach to restore the antioxidant capability of Res, also paves the way to precisely regulate the fascinating bioactivities of hydrophobic compounds by protein-binding in a chemical structure-, especially hydroxyl group-dependent manner.

Egg Yolk Selenopeptides: Preparation, Characterization, and Immunomodulatory Activity

In this study, egg yolk selenium peptides (Se-EYP) were prepared using double-enzyme hydrolysis combined with a shearing pretreatment. The properties of the selenopeptides formed were then characterized, including their yield, composition, molecular weight distribution, antioxidant activity, in vitro digestion, and immunomodulatory activity. The peptide yield obtained after enzymatic hydrolysis using a combination of alkaline protease and neutral protease was 74.5%, of which 82.6% had a molecular weight <1000 Da. The selenium content of the lyophilized solid product was 4.01 μg/g. Chromatography-mass spectrometry analysis showed that 88.6% of selenium in Se-EYP was in the organic form, of which SeMet accounted for 60.3%, SeCys2 for 21.8%, and MeSeCys for 17.9%. After being exposed to in vitro simulated digestion, Se-EYP still had 65.1% of oligopeptides present, and the in vitro antioxidant activity was enhanced. Moreover, Se-EYP exhibited superior immune detection indices, including immune organ index, level of immune factors in the serum, histopathological changes in the spleen, and selenium content in the liver. Our results suggest that Se-EYP may be used as selenium-enriched ingredients in functional food products.

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.

Moringa oleifera (drumstick tree)-nutraceutical, cosmetological and medicinal importance: a review

Moringa oleifera Lam. (Moringaceae) is a species of tree with an increasing utility, occurring naturally mainly in Pakistan and northern India. M. oleifera is currently cultivated in Africa, South America, Asia and the Middle East. The usage of its leaves, seed oil, bark, fruits, flowers and roots has positive opinions of FDA (American Food and Drug Administration), EFSA (European Food Safety Authority) and CosIng (Cosmetic Ingredients database). The chemical composition of M. oleifera is dominated by: proteins (consisting mainly of amino acids such as arginine or serine), fatty acids (omega-3 and omega-6), vitamins (vitamin A, B and C and tocopherols), mineral salts (including several bioelements, such as calcium, magnesium, sodium, and potassium), valuable polyphenolic compounds from the group of phenolic acids (e.g., gallic acid, ferulic acid) and flavonoids (e.g., myricetin, rutoside, and kaempferol). The raw materials show antioxidant, hepatoprotective, anti-inflammatory and antimicrobial properties. Dietary supplements and alimentary products containing M. oleifera are recommended as health-promoting and "novel food" preparations. The main purpose of this work was a review of the latest scientific literature on M. oleifera, with particular emphasis on the studies focusing on its chemical composition, biological activity and safety. Moreover, the review tends to discuss the results of biotechnological studies using this material and the agronomical significance.

Novel Antioxidant Peptides Derived from Feather Keratin Alleviate H2O2-Induced Oxidative Damage in HepG2 Cells via Keap1/Nrf2 Pathway

Reactive oxygen species (ROS) are crucial for signal transduction and the maintenance of cellular homeostasis. However, superfluous ROS may engender chronic pathologies. Feather keratin is a promising new source of antioxidant peptides that can eliminate excess ROS and potentially treat oxidative stress-related diseases, but the underlying mechanisms have remained elusive. This study investigated the antioxidant effects and mechanisms against H2O2-induced oxidative damage in HepG2 cells of the two latest discovered antioxidant peptides, CRPCGPTP (CP-8) and ANSCNEPCVR (AR-10), first decrypted from feather keratin. The results revealed that CP-8 and AR-10 did not exhibit cytotoxicity to HepG2 cells while reducing intracellular ROS accumulation. Simultaneously, they enhanced the activities of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px), thus alleviating H2O2-induced cell apoptosis. Molecular docking analysis demonstrated that CP-8, AR-10 interacted well with the key amino acids in the Kelch domain of Keap1, thereby directly disrupting the Keap1-Nrf2 interaction. The peptides' biosafety and antioxidant activity via Keap1/Nrf2 signaling lay the groundwork for further animal studies and applications as functional food additives.

Novel antioxidant peptides in fermented pork sausage: Purification, characterization, and cytoprotective functions on Caco-2 cells

In this study, crude peptides from fermented sausages inoculated with Lactobacillus plantarum CD101 and Staphylococcus simulans NJ201 were initially separated by ultrafiltration and molecular-sieve chromatography. The obtained fractions with high 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and ferric-reducing antioxidant power values (MWCO-1 and fraction A) were used in Caco-2 cells to evaluate their cytoprotective effect on oxidative damage triggered by H₂O₂. MWCO-1 and A showed slight cytotoxicity. Increased glutathione peroxidase, catalase, and superoxide dismutase activities and decreased malondialdehyde content were observed in the peptide-treated groups. Fraction A was further purified using reversed high-performance liquid chromatography. Eighty potential antioxidant peptides were identified by liquid chromatography with tandem mass spectrometry, and fourteen antioxidant peptides were synthesized. SDEEVEH and FAGDDAPR showed strong DPPH radical scavenging activity, whereas ALELDSNLYR and QEYDESGPSIVHR presented strong ABTS^+· scavenging activity. These peptides might have great potential for food and pharmacological applications.