Bioactive Peptides

Protective Effect and Gut Microbiota Modulation of Grifola frondosa Antioxidant Peptides in Sodium Dextran Sulfate-Induced Ulcerative Colitis Mice

Grifola frondosa antioxidant peptides (GFAP) were prepared through trypsin enzymolysis and characterized. This study conducted a comprehensive assessment of clinical symptoms, colon pathological injuries, levels of inflammatory factors, expression of inflammation-related proteins, and alterations in gut microbiota composition in mice with ulcerative colitis (UC). The findings demonstrated that GFAP effectively mitigated UC, alleviated mucosal damage, and reduced inflammatory infiltration. Specifically, GFAP administration resulted in significant reductions in pro-inflammatory cytokines IL-6, IL-1β, and TNF-α, while enhancing the expression levels of tight junction proteins such as Occludin and ZO-1. Additionally, GFAP treatment led to decreased levels of Toll-like receptor 4 (TLR-4), inducible nitric oxide synthase (iNOS), and TNF-α. Noteworthy, GFAP also influenced the gut microbiota by decreasing the abundance of Proteobacteria and increasing Bacteroidetes and Firmicutes. Moreover, specific bacteria like Bacteroides uniformis and Alistipes exhibited elevated abundances following GFAP treatment. In summary, GFAP exhibited preventive and protective effects against UC in mice by effectively alleviating clinical symptoms and modulating gut microbiota composition.

Exploring the potential of Lacticaseibacillus paracasei M11 on antidiabetic, anti-inflammatory, and ACE inhibitory effects of fermented dromedary camel milk (Camelus dromedaries) and the release of antidiabetic and anti-hypertensive peptides

The goal of this investigation was to find antidiabetic peptides and inhibit angiotensin converting enzyme (ACE) in Lacticaseibacillus paracasei (M11) fermented dromedary camel milk (Camelus dromedaries). According to the findings, the rate of antidiabetic activity increased along with the incubation periods and reached its peak after 48 hr of fermentation. The inhibitions of α-amylase, α-glucosidase, and lipase were 80.75, 59.62, and 65.46%, respectively. The inhibitory activity of ACE was 78.33%, and the proteolytic activity was 8.90 mg/mL. M11 at 0.25 mg/mL effectively suppressed LPS-induced pro-inflammatory cytokines and their mediators such as NO, TNF-α, IL-6, and IL-1β in RAW 264.7 cells. The rate of inoculum in the optimization phase was 1.5-2.5%, and the greatest proteolytic activity was observed after 48 hr of fermentation. The investigation of the above property in the ultrafiltered fermented milk exhibited the highest antidiabetic and ACE inhibition activities in the 3 kDa than 10 kDa fractions. The molecular weight was determined employing SDS-PAGE, and the six-peptide sequences were identified using 2D gel electrophoresis. Due to its high proteolytic activity, the L. paracasei strain has been reported to be useful in the production of ACE-inhibitory and antidiabetic peptides. Amino acid sequences such from ɑ1, ɑ2, and β-caseins have been identified within fermented camel milk by searching on online databases, including BIOPEP (for antidiabetic peptides) and AHTPDB (for hypertension peptides) to validate the antidiabetic and ACE-inhibitory actions of several peptides. PRACTICAL APPLICATIONS: The study aims to identify antidiabetic peptides and inhibit ACE in dromedary camel milk fermented with Lacticaseibacillus paracasei M11. Maximum antidiabetic and ACE-inhibitory actions of the fermented camel milk were observed in 3 kDa permeate fractions. Fermented camel milk significantly reduced the excessive TNF-α, IL-6, and IL-1β production in LPS-activated RAW 264.7 cells. RP-LC/MS was used to identify 6 bioactive peptides from dromedary fermented camel milk. This fermented camel milk could be used for the management of hypertension and diabetic related problems.

A comprehensive review of bioactive peptides obtained from animal byproducts and their applications

Livestock generates high quantities of residues, which has become a major socioeconomic issue for the meat industry. This review focuses on the identification of bioactive peptides (BPs) in animal byproducts and meat wastes. Firstly, the main bioactivities that peptides can have will be described and the methods for their evaluation will be discussed. Secondly, the various origins of these BPs will be studied. Then, the techniques and tools for the generation of BPs will be detailed in order to discuss, in the final part, how peptides could be used and assimilated. BPs possess diverse biological activities and can be strategic candidates for substituting synthetic molecules. In silico potentiality studies are a helpful tool to understand and predict BPs released from proteins and their potential activities. However, in vitro validation is often required. Although BP use is compelled by strict regulations in relation to the field of application, they are also limited by their low bioavailability and bioaccessibility. Therefore, it is important to test peptide stability during gastrointestinal digestion. Protective strategies have been discussed since their use could improve the stability and effectiveness of BPs.

In Silico and In Vitro Assessment of Portuguese Oyster (Crassostrea angulata) Proteins as Precursor of Bioactive Peptides

In this study, the potential bioactivities of Portuguese oyster (Crassostrea angulata) proteins were predicted through in silico analyses and confirmed by in vitro tests. C. angulata proteins were characterized by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and identified by proteomics techniques. Hydrolysis simulation by BIOPEP-UWM database revealed that pepsin (pH > 2) can theoretically release greatest amount of bioactive peptides from C. angulata proteins, predominantly angiotensin I-converting enzyme (ACE) and dipeptidyl peptidase IV (DPP-IV) inhibitory peptides, followed by stem bromelain and papain. Hydrolysates produced by pepsin, bromelain and papain have shown ACE and DPP-IV inhibitory activities in vitro, with pepsin hydrolysate (PEH) having the strongest activity of 78.18% and 44.34% at 2 mg/mL, respectively. Bioactivity assays of PEH fractions showed that low molecular weight (MW) fractions possessed stronger inhibitory activity than crude hydrolysate. Overall, in vitro analysis results corresponded with in silico predictions. Current findings suggest that in silico analysis is a rapid method to predict bioactive peptides in food proteins and determine suitable enzymes for hydrolysis. Moreover, C. angulata proteins can be a potential source of peptides with pharmaceutical and nutraceutical application.

Sonochemical action and reaction of edible insect protein: Influence on enzymolysis reaction-kinetics, free-Gibbs, structure, and antioxidant capacity

We investigated the impact of sonochemical action and the reaction of Hermetia illucens larvae meal protein (HILMP) as regards enzymolysis under varied enzyme concentration and temperature to explain the mechanism and effect of sonication on molecular conformation, limits of kinetics, free-Gibbs energy, and antioxidative capacity. Control treatment was used for comparison. The results showed sonochemical treatment enhanced HILMP-enzymolysis efficiency at various enzyme volume, and temperature. Enzymolysis-kinetics revealed sonochemical treatment increased the rate constant (p < .05) by 17.21%, 25.06%, 26.91%, and 41.38% at 323, 313, 303, and 293 K, respectively. On free-Gibbs, sonochemical treatment reduced the reactants-reactivity energy, enthalpy, and entropy by 30.53%, 35.05%, and 10.71%, respectively (p < .05). Changes in spectra of UV and fluorescence, and micrographic imaging indicated alterations of HILMP by sonochemical treatment. Antioxidative activity of sonochemically-treated HILMP increased, compared to control. Thus, sonochemical treatment may be beneficial in the production of edible insect proteins with smaller molecular weights for different food and/or pharmaceutical applications. PRACTICAL APPLICATIONS: Sonochemical pretreatment of HILMP positively impacted it enzymolysis rate-reaction, stability of reaction products, structure, and bioactivity. Thus, the technique may be beneficial to industry in the processing/development of new (bioactive/pharmaceutical) products involving enzymolysis of edible insects (e.g., Hermetia illucens) protein; particularly at such a time where edible insects are projected to be a source of protein for human nutrition and livestock in the next few years.

Discovery and Study of Novel Antihypertensive Peptides Derived from Cassia obtusifolia Seeds

Antihypertensive peptides were screened from thermolysin hydrolysate of Cassia obtusifolia seeds (Jue Ming Zi) using two independent bioassay-guided fractionations, reversed-phase high-performance liquid chromatography (RP-HPLC), and strong cation-exchange (SCX) liquid chromatography coupled with angiotensin I-converting enzyme (ACE) inhibitory assay. The identical peptide in the most active RP-HPLC and SCX fractions was simultaneously de novo sequenced as FHAPWK with high-resolution mass spectrometry. FHAPWK (IC₅₀ = 16.83 ± 0.90 μM) was further identified as a competitive inhibitor and a true inhibitor on ACE by a Lineweaver-Burk plot and preincubation experiment, respectively. The molecular docking simulation indicated that FHAPWK could interact with several key residues of the ACE active site, which is consistent with the result of the inhibitory kinetics study. Moreover, its antihypertensive effect was demonstrated using the animal model of spontaneously hypertensive rats. It is concluded that FHAPWK is the first reported antihypertensive peptide derived from thermolysin hydrolysate of C. obtusifolia seeds.

Production of Bioactive Peptides from Lactic Acid Bacteria: A Sustainable Approach for Healthier Foods

Traditional fermented foods where lactic acid bacteria (LAB) are present have been associated with beneficial effects on human health, and some of those benefits are related to protein-derived products. Peptides produced by LAB have attracted the interest of food industries because of their diverse applications. These peptides include ribosomally produced (bacteriocins) and protein hydrolysates by-products (bioactive peptides), which can participate as natural preservatives and nutraceuticals, respectively. It is essential to understand the biochemical pathways and the effect of growth conditions for the production of bioactive peptides and bacteriocins by LAB, in order to suggest strategies for optimization. LAB is an important food-grade expression system that can be used in the simultaneous production of peptide-based products for the food, animal, cosmetic, and pharmaceutical industries. This review describes the multifunctional proteinaceous compounds generated by LAB metabolism and discusses a strategy to use a single-step production process, using an alternative protein-based media. This strategy will provide economic advantages in fermentation processes and will also provide an environmental alternative to industrial waste valorization. New technologies that can be used to improve production and bioactivity of LAB-derived peptides are also analyzed.

Structural and functional properties of food protein-derived antioxidant peptides

The aim of this work is to provide a timely examination of the structure-activity relationship of antioxidative peptides. The main production approach involves enzymatic hydrolysis of animal and plant proteins to produce protein hydrolyzates, which can be further processed by membrane ultrafiltration into size-based peptide fractions. The hydrolyzates and peptide fractions can also be subjected to separation by column chromatography to obtain pure peptides. Although the structural basis for enhanced antioxidant activity varies, protein hydrolyzates and peptide fractions that contain largely low molecular weight peptides have generally been shown to be potent antioxidants. In addition to having hydrophobic amino acids such as Leu or Val in their N-terminal regions, protein hydrolyzates, and peptides containing the nucleophilic sulfur-containing amino acid residues (Cys and Met), aromatic amino acid residues (Phe, Trp, and Tyr) and/or the imidazole ring-containing His have been generally found to possess strong antioxidant properties. PRACTICAL APPLICATIONS: High levels of reactive oxygen species (ROS) in addition to the presence of metal cations can lead to oxidative stress, which promotes reactions that cause destruction of critical cellular biopolymers, such as proteins, lipids, and nucleic acids. Oxidative stress could be due to insufficient levels of natural cellular antioxidants, which enables accumulation of ROS to toxic levels. A proposed approach to ameliorating oxidative stress is the provision of exogenous peptides that can be consumed to complement cellular antioxidants. Food protein-derived peptides consist of amino acids joined by peptides bonds just like glutathione, a very powerful natural cellular antioxidant. Therefore, this review provides a timely summary of the in vitro and in vivo reactions impacted by antioxidant peptides and the postulated mechanisms of action, which could aid development of potent antioxidant agents. The review also serves as a resource material for identifying novel antioxidant peptide sources for the formulation of functional foods and nutraceuticals.

Anti-Cancer Activity of Maize Bioactive Peptides

Cancer is one of the main chronic degenerative diseases worldwide. In recent years, consumption of whole-grain cereals and their derivative food products has been associated with a reduced risk of various types of cancer. The main biomolecules in cereals include proteins, peptides, and amino acids, all of which are present in different quantities within the grain. Some of these peptides possess nutraceutical properties and exert biological effects that promote health and prevent cancer. In this review, we report the current status and advances in knowledge regarding the bioactive properties of maize peptides, such as antioxidant, antihypertensive, hepatoprotective, and anti-tumor activities. We also highlight the potential biological mechanisms through which maize bioactive peptides exert anti-cancer activity. Finally, we analyze and emphasize the potential applications of maize peptides.

Synergy of licorice extract and pea protein hydrolysate for oxidative stability of soybean oil-in-water emulsions

Previously developed radical-scavenging pea protein hydrolysates (PPHs) prepared with Flavourzyme (Fla-PPH) and Protamex (Pro-PPH) were used as cosurfactants with Tween 20 to produce soybean oil-in-water (O/W) emulsions, and the suppression of lipid oxidation was investigated. Both PPHs significantly retarded oxidation (P < 0.05) of the emulsions when stored at 37 °C for 14 days. Electron microscopy revealed an interfacial peptidyl membrane around oil droplets, which afforded steric restrictions to oxidation initiators. When licorice extract (LE) was also used in emulsion preparation, a remarkable synergistic oxidation inhibition was observed with both PPHs. LE adsorbed onto oil droplets either directly or through associating with PPH to produce a thick and compact interfacial membrane enabling the defense against oxygen species. Liquiritin apioside, neolicuroside, glabrene, and 18β-glycyrrhetic acid were the predominant phenolic derivatives partitioning at the interface and most likely the major contributors to the notable synergistic antioxidant activity when coupled with PPHs.

Interfacial structural role of pH-shifting processed pea protein in the oxidative stability of oil/water emulsions

Understanding the behavior of protein surfactants at the oil-water interface is essential to the design of physicochemically stable emulsions. The objective of the study was to investigate the steric role of an interfacial membrane made of structurally modified pea protein with alkaline pH treatment (APP) in the oxidative stability of oil-in-water emulsions. Confocal laser scanning microscopy depicted more uniform and smaller oil droplets that had a reduced tendency to coalesce for emulsions prepared with APP than with native pea protein (NPP). Correspondingly, the APP emulsions were less prone to oxidation (malonaldehyde, peroxide) during storage. Similarly, cryo-transmission electron microscopy revealed more uniform air pockets with smoother undersurface that were surrounded by partially coalesced emulsions in whipped creams prepared with APP than with NPP. The improved interfacial properties and steric hindrance played a crucial role in the inhibition of oxidation in emulsions by alkaline pH-modified pea protein.