Pigeon pea enzymatic protein hydrolysates and ultrafiltration peptide fractions as potential sources of antioxidant peptides: An in vitro study

Melittin alcalase-hydrolysate: a novel chemically characterized multifunctional bioagent; antibacterial, anti-biofilm and anticancer

The prevalent life-threatening microbial and cancer diseases and lack of effective pharmaceutical therapies created the need for new molecules with antimicrobial and anticancer potential. Bee venom (BV) was collected from honeybee workers, and melittin (NM) was extracted from BV and analyzed by urea-polyacrylamide gel electrophoresis (urea-PAGE). The isolated melittin was hydrolyzed with alcalase into new bioactive peptides and evaluated for their antimicrobial and anticancer activity. Gel filtration chromatography fractionated melittin hydrolysate (HM) into three significant fractions (F1, F2, and F3), that were characterized by electrospray ionization mass spectrometry (ESI-MS) and evaluated for their antimicrobial, anti-biofilm, antitumor, and anti-migration activities. All the tested peptides showed antimicrobial and anti-biofilm activities against Gram-positive and Gram-negative bacteria. Melittin and its fractions significantly inhibited the proliferation of two types of cancer cells (Huh-7 and HCT 116). Yet, melittin and its fractions did not affect the viability of normal human lung Wi-38 cells. The IC50 and selectivity index data evidenced the superiority of melittin peptide fractions over intact melittin. Melittin enzymatic hydrolysate is a promising novel product with high potential as an antibacterial and anticancer agent.

Pepsin immobilization on activated carbon and functionalized with glutaraldehyde and genipin for the synthesis of antioxidant peptides of goat casein

In this article, the synthesis of antioxidant peptides in the enzymatic hydrolysis of caprine casein was analyzed at three different time points (60 min, 90 min, and 120 min) using immobilized pepsin on activated and modified carbon (AC, ACF, ACG 50, ACG 100). The immobilization assays revealed a reduction in the biocatalysts' activity compared to the free enzyme. Among the modified ones, ACG 50 exhibited greater activity and better efficiency for reuse cycles, with superior values after 60 min and 90 min. Peptide synthesis was observed under all studied conditions. Analyses (DPPH, β-carotene/linoleic acid, FRAP) confirmed the antioxidant potential of the peptides generated by the immobilized enzyme. However, the immobilized enzyme in ACG 50 and ACG 100, combined with longer hydrolysis times, allowed the formation of peptides with an antioxidant capacity greater than or equivalent to those generated by the free enzyme, despite reduced enzymatic activity.

Study on the Digestion-Induced Changes in the Characteristics and Bioactivity of Korean Native and Overseas Cattle-Derived Peptides

This study was conducted to compare and analyze the changes in the biochemical characteristics and biological activity of peptide extracts derived from Chickso, Hanwoo, and Wagyu beef during digestion. The results of the in vitro digestion analysis revealed that the digestion rate, total free amino acid content, and antioxidant and antihypertensive activities of Chickso loin and shank myofibrillar proteins were significantly higher (p<0.05) than those of Hanwoo and Wagyu loin and shank myofibrillar proteins. Particularly, the peptide extracts of Chickso loin and shank had a high angiotensin-converting enzyme inhibitory activity. In mice in vivo digestion experiment, the blood serum of mice fed with Chickso loin peptide extract (<10 kDa) showed the highest antioxidant enzyme activity. Thus, Chickso peptide extracts were deemed to be similar or more bioactive than Hanwoo and Wagyu peptide extracts, and can be used as bioactive materials.

Preparation, characterization, and bioavailability evaluation of antioxidant phosvitin peptide-ferrous complex

BACKGROUND

Iron deficiency anemia (IDA) is one of the commonest global nutritional deficiency diseases, and the low bioavailability of iron is a key contributing factor. The peptide-iron complex could be used as a novel iron supplement to improve iron bioavailability.

RESULTS

In this study, antioxidant low molecular weight (<3 kDa) phosvitin peptide (named PP-4) was separated to prepare a phosvitin peptide-ferrous complex (named PP-4-Fe); then the structural conformation of PP-4-Fe was characterized and its bioavailability by in vitro digestion was evaluated. The results showed that PP-4 had good ferrous-binding activity with 96.14 ± 2.86 μg Fe2+ mg-1 , and had a strong antioxidant effect with 995.61 ± 79.75 μmol TE mg-1 in 2,2'-azinobis'3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 62.3 ± 3.95 μmol FeSO4 mg-1 in ferric ion reducing antioxidant power (FRAP). After ferrous binding, the FRAP activity of PP-4-Fe, enhanced by 1.8 times, formed a more ordered structure with an increase in α-helix and decrease in γ-random coil. The ferrous binding sites of PP-4 involved were the amino, carboxyl, imidazole, and phosphate groups. The PP-4-Fe complex displayed excellent gastrointestinal stability and antioxidant effects during digestion. The iron dialysis percentage of PP-4-Fe was 74.59% ± 0.68%, and increased to 81.10% ± 0.89% with the addition of 0.25 times vitamin C (VC). This indicated that PP-4-Fe displayed excellent bioavailability and VC in sufficient quantities had a synergistic effect on improving bioavailability.

CONCLUSIONS

This study demonstrated that antioxidant phosvitin peptide was an efficient delivery system to protect ferrous ions and suggested that the phosvitin peptide-ferrous complex has strong potential as a ferrous supplement. © 2023 Society of Chemical Industry.

Comparison of characteristics and antioxidant activities of sesame protein hydrolysates and their fractions

Sesame meal is a by-product obtained from oil extraction. We investigated the characteristics and antioxidant activities of a sesame protein hydrolysate (SPH-B), as well as its peptide fractions. Four peptide fractions (F1; >100 kDa, F2; 10-100 kDa, F3; 1-10 kDa, and F4; <1 kDa) of SPH-B were prepared. The characteristics and antioxidant properties of SPH-B and its peptide fractions were evaluated. Sesame protein (SP) contained protein fractions with molecular weights ranging from 10 to 44 kDa, whereas SPH-B had peptide fractions ranging from 8 to 44 kDa. The peptide fractions had molecular weight ranging from 7 to 10 kDa. The four peptide fractions had a higher α-helix content and lower surface hydrophobicity than SPH-B and SP. They exhibited better antioxidant properties, with higher ABTS and DPPH radical scavenging activities, higher metal chelating activity, and greater inhibition of linoleic acid peroxidation, suggesting that sesame peptide fractions can use as plant-based functional ingredients and potentially health-promoting properties.

Determination of the effects of proteolysis-based changes by adjunct lactobacilli on the bioactivity (ACE-inhibitory and antioxidant activities) of cheese: a model cheese study

Bioactive properties, proteolysis and microbiology of model cheeses with and without adjunct lactobacilli (Lactobacillus helveticus, Lactiplantibacillus plantarum, Lactobacillus bulgaricus and L. casei) were studied during 120 days of storage at 8 or 16 °C. Bioactive properties were observed in peptide fractions (< 3 kDa, 3-10 kDa, < 10 kDa) separated using ultrafiltration membranes. Antioxidant activity of these fractions was determined by radical scavenging assays as ABTS [2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)]. Angiotensin-converting enzyme-inhibitory (ACE-i) activity (% and IC50) and peptide profiles of 70% ethanol-soluble and -insoluble fractions were determined by RP-HPLC. Use of lactobacilli as an adjunct culture significantly changed the RP-HPLC peptide profiles of the cheeses; however, slight changes were observed in the patterns of urea-polyacrylamide gel electrophoresis. Fractions smaller than 3 kDa had higher ACE-i and antioxidant activities for all cheese samples. In conclusion, this study indicates that the addition of lactobacilli as an adjunct culture contributed to the formation of bioactive compounds in the model cheeses and also changed the proteolysis levels.

Plant Protein-Derived Active Peptides: A Comprehensive Review

Active peptides are a class of physiologically active protein fragments, which can be prepared from different sources. In the past few decades, the production of peptides with various effects from different plant proteins continues to receive academic attention. With advances in extraction, purification, and characterization techniques, plant protein-derived active peptides continue to be discovered. They have been proven to have various functional activities such as antioxidant, antihypertensive, immunomodulatory, antimicrobial, anti-inflammatory, antidiabetic, antithrombotic, and so on. In this review, we searched Web of Science and China National Knowledge Infrastructure for relevant articles published in recent years. There are 184 articles included in this manuscript. The current status of plant protein-derived active peptides is systematically introduced, including their sources, preparation, purification and identification methods, physiological activities, and applications in the food industry. Special emphasis has been placed on the problems of active peptide exploration and the future trend. Based on these, it is expected to provide theoretical reference for the further exploitation of plant protein-derived active peptides, and promote the healthy and rapid development of active peptide industry.

Protein Hydrolysate from Underutilized Legumes: Unleashing the Potential for Future Functional Foods

Proteins play a vital role in human development, growth, and overall health. Traditionally, animal-derived proteins were considered the primary source of dietary protein. However, in recent years, there has been a remarkable shift in dietary consumption patterns, with a growing preference for plant-based protein sources. This shift has resulted in a significant increase in the production of plant proteins in the food sector. Consequently, there has been a surge in research exploring various plant sources, particularly wild, and underutilized legumes such as Canavalia, Psophocarpus, Cajanus, Lablab, Phaseolus, and Vigna, due to their exceptional nutraceutical value. This review presents the latest insights into innovative approaches used to extract proteins from underutilized legumes. Furthermore, it highlights the purification of protein hydrolysate using Fast Protein Liquid Chromatography. This review also covers the characterization of purified peptides, including their molecular weight, amino acid composition, and the creation of three-dimensional models based on amino acid sequences. The potential of underutilized legume protein hydrolysates as functional ingredients in the food industry is a key focus of this review. By incorporating these protein sources into food production, we can foster sustainable and healthy practices while minimizing environmental impact. The investigation of underutilized legumes offers exciting possibilities for future research and development in this area, further enhancing the utilization of plant-based protein sources.

A comprehensive review of mung bean proteins: Extraction, characterization, biological potential, techno-functional properties, modifications, and applications

The popularity of plant-based proteins has increased, and mung bean protein (MBP) has gained immense attention due to its high yield, nutritional value, and health benefits. MBP is rich in lysine and has a highly digestible indispensable amino acid score. Dry and wet extractions are used to extract MBP flours and concentrates/isolates, respectively. To enhance the quality of commercial MBP flours, further research is needed to refine the purity of MBPs using dry extraction methods. Furthermore, MBP possesses various biological potential and techno-functional properties, but its use in food systems is limited by some poor functionalities, such as solubility. Physical, biological, and chemical technologies have been used to improve the techno-functional properties of MBP, which has expanded its applications in traditional foods and novel fields, such as microencapsulation, three-dimensional printing, meat analogs, and protein-based films. However, study on each modification technique remains inadequate. Future research should prioritize exploring the impact of these modifications on the biological potential of MBP and its internal mechanisms of action. This review aims to provide ideas and references for future research and the development of MBP processing technology.

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.

Continuous production of velvet bean-based bioactive peptides in membrane reactor with dual enzyme system

One of the main challenges hindering the commercialization of bioactive peptides is the lack of scalable and consistent production methods. To overcome this obstacle, an automated enzyme membrane reactor was used to continuously produce bioactive peptides from velvet bean (Mucuna pruriens). The optimum operating conditions were [E]/[S] = 5%, pH = 7.5, and τ = 12 h. The long-term continuous operation of the EMR system demonstrated its ability to maintain steady-state conditions. To minimize membrane fouling, an industrially viable strategy was employed, which combines operation at threshold flux and performing regular membrane cleaning. Further fractionation of the hydrolysates with a 2-kDa PES membrane resulted in the highest bioactivity. The IC₅₀ values for antioxidant and ACE inhibition were 17.85 and 4.58 µg protein/mL, respectively. To map the overall bioactivities of the hydrolysates, LC-MS analysis coupled with BIOPEP-UWM database was performed and obtained DPP-4 and ACE inhibitors as the predominant bioactive activities.

Protective Effect of Peptides from Pinctada Martensii Meat on the H2O2-Induced Oxidative Injured HepG2 Cells

Pinctada martensii is a major marine pearl cultured species in southern China, and its meat is rich in protein, which is an excellent material for the preparation of bioactive peptides. In this study, the peptides from Pinctada martensii meat were prepared by simulated gastrointestinal hydrolysis, and after multistep purification, the structures of the peptides were identified, followed by the solid-phase synthesis of the potential antioxidant peptides. Finally, the antioxidant activities of the peptides were verified using HepG2 cells, whose oxidative stress was induced by hydrogen peroxide (H₂O₂). It was shown that the antioxidant peptide (S4) obtained from Pinctada martensii meat could significantly increase the cell viability of HepG2 cells. S4 could also scavenge reactive oxygen species (ROS) and reduce the lactate dehydrogenase (LDH) level. In addition, it could enhance the production of glutathione (GSH) and catalase (CAT) in HepG2 cells, as well as the expression of key genes in the Nrf2 signaling pathway. Three novel antioxidant peptides, arginine-leucine (RL), arginine-glycine-leucine (RGL), and proline-arginine (PR), were also identified. In conclusion, peptides from Pinctada martensii meat and three synthetic peptides (RGL, RL, PR) showed antioxidant activity and could have the potential to be used as antioxidant candidates in functional foods.

Optimization of enzymatic hydrolysis by alcalase and flavourzyme to enhance the antioxidant properties of jasmine rice bran protein hydrolysate

This study aimed to optimize the hydrolysis conditions for producing jasmine rice bran protein hydrolysate (JBH) using response surface methodology (RSM). The independent variables were the ratio of flavourzyme to alcalase (Fl:Al; 0: 100 to 15: 85; 2.84% enzyme concentration) and hydrolysis time (60–540 min). The optimum hydrolysate was obtained at an Fl:Al ratio of 9.81: 90.19 for 60 min, since it enabled high amounts of protein, high antioxidant activity and more low molecular weight proteins. The experimental values obtained were a degree of hydrolysis (DH) of 7.18%, a protein content of 41.73%, an IC₅₀ for DPPH of 6.59 mg/mL, an IC₅₀ for ABTS of 0.99 mg/mL, FRAP of 724.81 mmol FeSO₄/100 g, and 322.35 and 479.05 mAU*s for peptides with a molecular weight of < 3 and 3–5 kDa, respectively. Using a mixture of enzymes revealed the potential of mixed enzymes to produce JBH containing more small peptides and high antioxidant activity.

Pigeon pea penta- and hexapeptides with antioxidant properties also inhibit renin and angiotensin-I-converting enzyme activities

Pigeon pea protein was sequentially digested with pepsin followed by pancreatin and the hydrolysate separated into 18 fractions using reversed-phase high-performance liquid chromatography. Fractions were analyzed for in vitro antioxidant properties (radical scavenging, metal chelation, and ferric iron reducing ability) in addition to inhibition of renin and angiotensin-converting enzyme (ACE). The most active fractions were analyzed by mass spectroscopy followed by identification of 10 peptide sequences (7 pentapeptides and 3 hexapeptides). All the peptides showed a wide range of multifunctional activity by scavenging hydroxyl (31.9-66.8%) and superoxide (25.6-100.0%) radicals in addition to ACE inhibition (7.4-100%) with significant (p < .05) differences between the peptides. AGVTVS, TKDIG, TSRLG, GRIST, and SGEKI were the most active; however, AGVTVS had the highest hydrophobic residue and exhibited the strongest activity against ACE, renin as well as superoxide and hydroxyl radicals. PRACTICAL APPLICATIONS: There is an increasing attraction of researchers to food peptides especially from legume proteins. Enzymatic digestion as well as high performance liquid chromatography (HPLC) purification has become an important process used to separate peptides with significant biological activities and health-promoting effects. There is useful information regarding the bioactive and functional (in vitro antioxidant, antidiabetic, in vitro/in vivo antihypertensive) properties of hydrolyzed and ultra-filtered pigeon pea fractions but scant research output still exists for purified peptides from pigeon pea establishing their therapeutic potential. The present study aimed to separate peptide fractions from pigeon pea hydrolysate and identify available amino acid sequences from the parent protein. Therefore, peptide sequences generated from the most bioactive fractions showed prospects for the expanded industrial utilization of pigeon pea. Further promoting its application as functional ingredient or additive for alleviating angiotensin-converting enzyme-related diseases.

Acetylcholinesterase and butyrylcholinesterase inhibitory activities of antioxidant peptides obtained from enzymatic pea protein hydrolysates and their ultrafiltration peptide fractions

This study optimized the enzymatic hydrolysis of yellow field pea proteins using alcalase (ACH), chymotrypsin (CHH), flavourzyme (FZH), pancreatin (PCH), pepsin (PEH), and trypsin (TPH) to obtain hydrolysates and ultrafiltered fractions (<1, 1-3, 3-5 and 5-10 kDa) that possess antioxidant plus acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory activities. The hydrolysates exhibited varying degrees of radical scavenging and inhibition of linoleic acid peroxidation, as well as cholinesterase inhibition activities but the potency generally improved by >10% after UF separation into peptide fractions. ACH, FZH, and PEH exhibited significantly (p < .05) higher (20%-30% increases) radical scavenging activities than the other hydrolysates. The 1 and 3 kDa UF fractions of ACH, FZH, and PEH inhibited ~20%-30% AChE activity, while ACH, PCH, TPH, and PEH inhibited ~20%-40% BuChE activity. We conclude that the pea protein hydrolysates and their peptide fractions possess multifunctional properties with potential use against neurodegenerative disorders. PRACTICAL APPLICATIONS: Alzheimer's disease (AD) has multiple pathological pathways in addition to the loss of acetylcholine (ACh) catalyzed by acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). The presence of severe oxidative stress triggered by lipid peroxidation and formation of free radicals is a common trait in AD patients. The concept of AChE and BuChE inhibition as an approach toward AD amelioration involves the use of compounds with a similar structure to ACh, the natural substrate. Peptides derived from food proteins consist of ester bonds with structural similarity to ACh and theoretically possess the ability to interact with AChE and BuChE. Results from the present study imply that pea protein-derived peptides are potential candidates for use as inhibitors of AChE and BuChE activities, with application in the prevention and management of AD.

Bioactive and health-promoting properties of enzymatic hydrolysates of legume proteins: a review

This study comprehensively reviewed the effect of controlled enzymatic hydrolysis on the bioactivity of pulse protein hydrolysates (PPHs). Proteolysis results in the partial structural unfolding of pulse proteins with an increase in buried hydrophobic groups of peptide sequences. The use of PPHs in a dose-dependent manner can enhance free radical scavenging and improve antioxidant activities regarding inhibition of lipid oxidation, ferric reducing power, metal ion chelation, and β-carotene bleaching inhibition. Ultrafiltered peptide fractions with low molecular weights imparted angiotensin-I converting enzyme (ACE) inhibitory effects during in vitro simulated gastrointestinal digestion and in vivo conditions. Ultrasonication, high-pressure pretreatments, and glycosylation as post-treatments can improve the antiradical, antioxidant, and ACE inhibitory activities of PPHs. The electrostatic attachment of pulse peptides to microbial cells can inhibit the growth and activity of bacteria and fungi. Bioactive pulse peptides can reduce serum cholesterol and triglycerides, and inhibit the formation of adipocyte lipid storage, allergenic factors, inflammatory markers, and arterial thrombus without cytotoxicity. The combination of germination and enzymatic hydrolysis can significantly increase the protein digestibility and bioavailability of essential amino acids. Moreover, the utilization and enrichment of bakery and meat products with functional PPHs ensure quality, safety, and health aspects of food products.

Bioengineered Lab-Grown Meat-like Constructs through 3D Bioprinting of Antioxidative Protein Hydrolysates

Lab-grown bovine meat analogues are emerging alternatives to animal sacrifices for cultured meat production. The most challenging aspect of the production process is the rapid proliferation of cells and establishment of the desired 3D structure for mass production. In this study, we developed a direct ink writing-based 3D-bioprinted meat culture platform composed of 6% (w/v) alginate and 4% (w/v) gelatin (Alg/Gel)-based hydrogel scaffolds supplemented with naturally derived protein hydrolysates (PHs; 10%) from highly nutritive plants (soybean, pigeon pea, and wheat), and some selected edible insects (beetles, crickets, and mealworms) on in vitro proliferation of bovine myosatellite cells (bMSCs) extracted from fresh meat samples. The developed bioink exhibited excellent shear-thinning behavior (n < 1) and mechanical stability during 3D bioprinting. Commercial proteases (Alcalase, Neutrase, and Flavourzyme) were used for protein hydrolysis. The resulting hydrolysates exhibited lower-molecular-weight bands (12-50 kDa) than those of crude isolates (55-160 kDa), as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The degree of hydrolysis was higher in the presence of Alcalase for both plant (34%) and insect (62%) PHs than other enzymes. The 3D-printed hydrogel scaffolds displayed excellent bioactivity and stability after 7 days of incubation. The developed prototype structure (pepperoni meat, 20 × 20 × 5 mm) provided a highly stable, nutritious, and mechanically strong structure that supported the rapid proliferation of myoblasts in a low-serum environment during the entire culture period. The 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay enhanced the free radical reduction of Alcalase- and Neutrase-treated PHs. Furthermore, the bioprinted bMSCs displayed early myogenesis (desmin and Pax7) in the presence of PHs, suggesting its role in bMSC differentiation. In conclusion, we developed a 3D bioprinted and bioactive meat culture platform using Alg/Gel/PHs as a printable and edible component for the mass production of cultured meat.

Protective effects of oyster protein hydrolysates on alcohol-induced liver disease (ALD) in mice: based on the mechanism of anti-oxidative metabolism

Many bioactivities of hydrolysates from oyster (Crassostrea gigas) muscle have been reported, while there is no knowledge about their protective effects on alcohol-induced liver disease (ALD). In the present study, the anti-oxidative activities in vitro and molecular weight distribution of oyster protein hydrolysates (OPH) were detected and the OPH released by alcalase (AOPH) was used to treat C57BL/6 mice. C57BL/6 mice were treated with a Lindros control diet to establish an ethanol-exposed model. The content of small-weight components (<2.0 kDa) of OPH reached 90.85%. AOPH showed more potent antioxidant activities in vitro with higher reducing power and ferric reducing antioxidant power (FRAP), and those capacities could be maintained at a high level after simulated gastrointestinal digestion. Compared to the model mice, oral administration (4 weeks) of AOPH at 800 mg per kg body weight could lead to a decline in T-AOC, GSH-PX, and ADH in the liver. The hepatocellular lesions were effectively relieved and impaired liver tissue development was successfully inhibited. A total of 834 genes and 54 proteins showed differential expression in the AOPH group and the oxidative metabolic pathways of ethanol such as oxidative phosphorylation, glutathione metabolism, peroxisomes, the PPAR signaling pathway and drug metabolism-cytochrome P450 play a preeminent role in ALD according to the results of transcriptomics and proteomics. The beneficial effects of AOPH were available in the improvement of ALD. These results revealed that AOPH intervention ameliorated ALD by affecting oxidative metabolism and highlighting AOPH's potential application as a functional food.

Production, Purification, and Potential Health Applications of Edible Seeds' Bioactive Peptides: A Concise Review

Edible seeds play a significant role in contributing essential nutritional needs and impart several health benefits to improve the quality of human life. Previous literature evidence has confirmed that edible seed proteins, their enzymatic hydrolysates, and bioactive peptides (BAPs) have proven and potential attributes to ameliorate numerous chronic disorders through the modulation of activities of several molecular markers. Edible seed-derived proteins and peptides have gained much interest from researchers worldwide as ingredients to formulate therapeutic functional foods and nutraceuticals. In this review, four main methods are discussed (enzymatic hydrolysis, gastrointestinal digestion, fermentation, and genetic engineering) that are used for the production of BAPs, including their purification and characterization. This article’s main aim is to provide current knowledge regarding several health-promoting properties of edible seed BAPs in terms of antihypertensive, anti-cancer, antioxidative, anti-inflammatory, and hypoglycemic activities.

Preparation and in vitro bioactive evaluation of cashew-nut proteins hydrolysate as a potential source of anti-allergy peptides

This work proposes a novel potential source of antiallergens based on bioactive peptides. Cashew-nut protein hydrolysate with antiallergic activity was prepared from cashew nuts through protease treatment. The change in the antiallergic activity of cashew-nut protein hydrolysate during in vitro simulated digestion was investigated. Cashew-nut protein hydrolysates were prepared through treatment using five different enzymes, namely, Alcalase, Protamex, Neutrase, papain, and bromelin. According to the results of molecular weight distribution, more small molecular weight peptides could be obtained by selecting Alcalase protease than other proteases, and the degree of hydrolysis, trichloroacetic acid-soluble peptide yield and hyaluronidase inhibitory rate of the hydrolysate were 17.0 ± 61.52%, 26.28 ± 0.13% and 62.06% ± 5.07%, which were significantly higher than those of other proteases. Therefore, Alcalase is the most suitable protease for the preparation of cashew-nut hydrolysates. Cashew-nut protein hydrolysates prepared with Alcalase under optimum conditions were fractionated through ultrafiltration. Fractions with low molecular weight exhibited the highest hyaluronidase inhibitory rate (90.57%) among all fractions. The inhibition of hyaluronidase activity during digestion showed that cashew-nut protein hydrolysate III (CPH III) has persistent antiallergic activity. Therefore, CPH III could serve as a potential source of functional peptides with health-promoting effects.

Antioxidant and Angiotensin I-Converting Enzyme (ACE) Inhibitory Peptides Obtained from Alcalase Protein Hydrolysate Fractions of Hemp (Cannabis sativa L.) Bran

Proteins from hemp bran (HPB), a byproduct of the hemp seed food-processing chain, were chemically extracted, hydrolyzed by Alcalase, and separated by membrane ultrafiltration into four fractions (MW <1, 1-3, 3-5, and >5 kDa). The antioxidant and antihypertensive properties of the initial extract and the fractions were evaluated by in vitro assays for their ability to scavenge radical species, bind with metal ions, reduce ferric ions, and inhibit angiotensin-converting enzyme (ACE) activity. Bioactive peptides were identified by high-resolution mass spectrometry and sequence comparison with BIOPEP and BioPep DB databases. The hydrolysate was strongly antioxidant and ACE-inhibiting; the most bioactive peptides were further concentrated by ultrafiltration. Of the 239 peptides identified, 47 (12 antioxidant and 35 ACE-inhibitory) exhibited structural features correlated with the specific bioactivity. These results highlight the promise of hydrolysate and size-based HPB fractions as natural functional ingredients for the food or pharmaceutical industry.

Production and antioxidant capacity of bioactive peptides from plant biomass to counteract lipid oxidation

Preventing lipid oxidation, especially with the polyunsaturated fat-based products, is a major concern in sectors as agri-food and cosmetic. Even though the efficiency of synthetic antioxidants has been recognized, both consumers and manufacturers are looking for more innovative, healthy and quality products while rejecting synthetic additives due to their concern about safety, along with their environmental impact issues. In this context, plant biomass, which have shown to be rich in compounds, have raised interest for the isolation of novel naturally occurring antioxidants. Among their myriad of molecules, bioactive peptides, which are biologically active sequence of amino acid residues of proteins, seem to be of a great interest. Therefore, the number of identified amino acids sequences of bioactive peptides from plant biomass with potential antioxidant action is progressively increasing. Thus, this review provides a description of 129 works that have been made to produce bioactive peptides (hydrolysate, fraction and/or isolate peptide) from 55 plant biomass, along with the procedure to examine their antioxidant capacity (until 2019 included). The protein name, the process, and the method to concentrate or isolate antioxidant bioactive peptides, along with their identification and/or specificity were described. Considering the complex, dynamic and multifactorial physico-chemical mechanisms of the lipid oxidation, an appropriate in-vitro methodology should be better performed to efficiently probe the antioxidant potential of bioactive peptides. Therefore, the results were discussed, and perspective for antioxidant applications of bioactive peptides from plant biomass was argued.

Effect of Protease Type and Peptide Size on the In Vitro Antioxidant, Antihypertensive and Anti-Diabetic Activities of Eggplant Leaf Protein Hydrolysates

Solanum macrocarpon (eggplant) leaf protein isolate (ELI) was hydrolyzed using four different enzymes to produce hydrolysates from alcalase (AH), chymotrypsin (CH) pepsin (PH) and trypsin (TH). CH had an overall stronger antioxidant property and was separated using ultrafiltration membranes into <1, 1–3 and 3–5 kDa peptide fractions. Gel-permeation chromatography confirmed conversion of the ELI (average of 22 kDa) into protein hydrolysates that contained smaller peptides (<6 kDa). A total of 23 peptides consisting of tri and tetrapeptides were identified from the CH, which is a wider spectrum when compared to seven for AH and four each for TH and PH. CH exhibited stronger scavenging activities against DPPH and hydroxyl radicals. CH and TH exhibited the strongest inhibitions against angiotensin-converting enzyme. In contrast, AH was the strongest inhibitor of α-amylase while AH and PH had strong inhibitory activities against α-glucosidase when compared with other hydrolysates. Ultrafiltration fractionation produced peptides that were stronger (p < 0.05) scavengers of DPPH, and hydroxyl radicals, in addition to better metal-chelating and enzyme inhibition agents. The study concluded that the eggplant protein hydrolysates and the UF fractions may find applications in tackling oxidative stress-related diseases and conditions involving excessive activities of the metabolic enzymes.

Recent Advancements of UF-Based Separation for Selective Enrichment of Proteins and Bioactive Peptides—A Review

Proteins are one of the primary building blocks that have significant functional properties to be applied in food and pharmaceutical industries. Proteins could be beneficial in their concentrated products or isolates, of which membrane-based filtration methods such as ultrafiltration (UF) encompass application in broad spectra of protein sources. More importantly, selective enrichment by UF is of immense interest due to the presence of antinutrients that may dominate their perspicuous bioactivities. UF process is primarily obstructed by concentration polarization and fouling; in turn, a trade-off between productivity and selectivity emerges, especially when pure isolates are an ultimate goal. Several factors such as operating conditions and membrane equipment could leverage those pervasive contributions; therefore, UF protocols should be optimized for each unique protein mixture and mode of configuration. For instance, employing charged UF membranes or combining UF membranes with electrodialysis enables efficient separation of proteins with a similar molecular weight, which is hard to achieve by the conventional UF membrane. Meanwhile, some proposed strategies, such as utilizing ultrasonic waves, tuning operating conditions, and modifying membrane surfaces, can effectively mitigate fouling issues. A plethora of advancements in UF, from their membrane material modification to the arrangement of new configurations, contribute to the quest to actualize promising potentials of protein separation by UF, and they are reviewed in this paper.

Antioxidant mechanism, antibacterial activity, and functional characterization of peptide fractions obtained from barred mackerel gelatin with a focus on application in carbonated beverages

The present study aimed to use fish by-products to generate gelatin peptides with potential applications in carbonated beverages. After ultrafiltration, the F < 3 kDa (fraction < 3 kDa) showed the highest peptide concentration (227.22 mg/g) as well as antibacterial (MIC of ≤ 0.5 mg/mL) and antioxidant activities, including hydroxyl and superoxide radical scavenging, ferrous chelation, and ferric reduction (with IC₅₀ values of 0.88, 1.04, 0.50 mg/mL, and 0.58, respectively). 2,2-diphenyl-1-picrylhydrazyl scavenging was the highest in the 3 < F < 10 kDa (IC₅₀ of 0.64 mg/mL). In vitro gastrointestinal digestion significantly decreased all biological activities. Solubility, water holding capacity, and emulsifying activity of the F < 3 kDa were the highest while foaming properties and overfoaming were reversibly related to the molecular weight. All abovementioned properties, in addition to in vitro cytotoxicity analysis in different cell lines and better flavor characteristics, indicated that the F < 3 kDa could be safely and properly used as an ingredient for the fortification of carbonated beverages.

Thermoase-hydrolysed pigeon pea protein and its membrane fractions possess in vitro bioactive properties (antioxidative, antihypertensive, and antidiabetic)

Enzymatic hydrolysis can liberate bioactive peptides from protein materials, thus, pigeon pea was hydrolysed using thermoase. Crude hydrolysate (PPHT) was subjected to ultrafiltration using different molecular weight cutoffs to collect <1, 1-3, 3-5, 5-10, and >10 kDa peptide fractions. Fractions were analysed for in vitro antioxidative, antihypertensive, and antidiabetic properties. The peptide fractions had stronger DPPH^• scavenging and renin inhibition when compared to PPHT. In contrast, ACE inhibition was stronger for the PPHT and <1 kDa peptide fraction while activity decreased as peptide size increased. The <1 kDa peptide also showed significantly stronger ferric reducing antioxidant power, OH^• scavenging and inhibition of linoleic acid oxidation when compared to PPHT. α-amylase and α-glucosidase were inhibited by all the peptide fractions, though the 3-5 and >10 kDa had higher values. We conclude that the PPHT and peptide fractions could serve as potential ingredients to formulate antihypertensive and antidiabetic functional foods and nutraceuticals. PRACTICAL APPLICATIONS: Oxidative stress promotes the generation of free radicals, which have a significant impact in the pathogenesis of human chronic diseases such as cardiovascular impairment, cancer, and diabetes. Peptides generated from enzymatic hydrolysis of proteins have been identified to impart beneficial health effects. In this work, we showed that a thermoase digest of pigeon pea protein as well as the fractionated peptides had strong antioxidant properties in addition to exhibiting inhibitory activities against renin and angiotensin converting enzyme, the main therapeutic targets for antihypertensive agents. The peptide products also inhibited α-amylase and α-glucosidase activities, providing potential ingredients that can be used to formulate antidiabetic functional foods.

Antioxidant and enzymes inhibitory properties of Amaranth leaf protein hydrolyzates and ultrafiltration peptide fractions

Amaranth leaf protein isolate (ALI) was hydrolyzed using four different proteases (alcalase, trypsin, pepsin, and chymotrypsin) followed by fractionation of the pepsin hydrolyzate (PH) into different sizes using ultrafiltration membrane. Gel permeation chromatography showed that all the hydrolyzates had smaller size peptides (<7 kDa) than the protein isolate (>32 kDa). The chymotrypsin hydrolyzate had higher contents of hydrophobic amino acid (44.95%) compared to alcalase (42.72%), pepsin (43.93%), and trypsin (40.95%) hydrolyzates. The PH had stronger DPPH, hydroxyl radical, and superoxide radical scavenging activities than the other protein hydrolyzates but weaker Ferric reducing antioxidant power and metal chelating activities when compared to the peptide fractions. The <1 kDa peptide fraction exhibited stronger DPPH, hydroxyl, and superoxide radicals scavenging activities than the higher molecular weight (>1 kDa) fractions. Fractionation of PH also resulted in enhanced inhibition of α-amylase and ACE activities but weaker α-glucosidase inhibition. PRACTICAL APPLICATIONS: ALI was hydrolyzed using four proteases to produce protein hydrolyzates. The most active of the hydrolyzate was then fractionated to produce fractions of different molecular sizes. The results of the analyses showed that the hydrolyzates and the fractions showed good antioxidant and enzyme inhibitory activities such as the inhibition of ACE, α-amylase, and glucosidase enzymes. The results suggest that the enzymatic hydrolyzates and peptide fractions could be used as ingredients in the nutraceutical and functional food industries to scavenge free radicals and inhibit angiotensin-converting enzyme activity.

Functional properties and antioxidant activity of gelatine and hydrolysate from deer antler base

Gelatine was extracted from deer antler base by the hot water method and hydrolyzed with trypsin. A comparison of the properties of gelatine before and after enzymatic hydrolysis showed a decline in the surface hydrophobicity, enhanced thermal stability, broadening of the particle size distribution, a zeta potential shift to a lower pH, reduced foaming and emulsifying properties, and enhanced antioxidant activity. Hydrolysis increased the gelatine antioxidant activity in DPPH and FRAP assays. These results indicate that the functional properties of deer antler base gelatine may be affected by trypsin modification.

Evaluation of antioxidant peptides generated from Jiuzao (residue after Baijiu distillation) protein hydrolysates and their effect of enhancing healthy value of Chinese Baijiu

BACKGROUND

Jiuzao is the residue after Bajiu distillation which is usually used as forage for livestock. However, it is not fully utilized yet considering the content of protein remained. The present study aimed to isolate antioxidant peptides from Jiuzao protein hydrolysates, then add these peptides into Baijiu product to enhance the healthy value of Baiju. Meanwhile environmental pollution caused by massive Jiuzao can be mitigated indirectly.

RESULTS

Four peptides Ala-Tyr-Ile(Leu) (AYI(L)) and Asp-Arg-Glu-Ile(Leu) (DREI(L)) were identified from Jiuzao protein hydrolysates, the extraction contents of AYI + AYL and DREI + DREL were 896.10 and 110.51 mg kg^-1 Jiuzao, respectively. On the one hand, antioxidant activities of these peptides were investigated. For in vitro antioxidant assays, AYI, AYL and DREI exhibited strong capacities in oxygen radical absorbance capacity (ORAC) assay. Furthermore, three levels of four peptides were assessed by 2,2'-azobis(2-methylpropanimidamidine) (AAPH)-induced HepG2 cells model. The results showed that these peptides exerted a degree of antioxidant activities in cells. Meanwhile, selected peptides concentrations according to cell assays remined at effective doses after in vitro digestion. On the other hand, the influence of these four peptides on the characteristic aroma compounds in Baijiu was studied. Most characteristic aroma compounds releases were increased with the addition of peptides.

CONCLUSION

In the study, antioxidant activities of peptides were evaluated, the feasibility of utilizing Jiuzao protein hydrolysates to obtain beneficial peptides was also proved. Healthy effect of Baijiu or other food can be increased by adding these functional substances. The findings might contribute to food application and Baijiu industries. © 2019 Society of Chemical Industry.

Mung Bean Protein Hydrolysates Protect Mouse Liver Cell Line Nctc-1469 Cell from Hydrogen Peroxide-Induced Cell Injury

Mung bean is nutritious and rich in protein (19.5%–33.1%). However, there are few studies on mung bean protein active peptides so the mung bean protein hydrolysates (MBPHs) were investigated for evaluating their ability to clear intracellular reactive oxygen species (ROS) and regulating the ability of antioxidant enzymes on NCTC-1469 cells. Results showed that MBPHs, MBPHs-I (molecular weight < 3 kDa), MBPHs-II (molecular weight between 3 and 10 kDa), and MBPHs-III (molecular weight > 10 kDa) could all improve the survival rate of cells compared with the model group. MBPHs, MBPHs-I, and MBPHs-II could significantly decrease the content of lactate dehydrogenase (LDH) and reduce the generation of malonaldehyde (MDA) at a concentration of 0.4 mg/mL. Regarding the intracellular ROS, the result showed that MBPHs-I significantly reduced the production of ROS (from 58.3% to 26.6%) and had a dose-dependent relationship. In addition, the amino acid analysis showed that MBPHs-I had a balanced amino acid composition. MBPHs-I is rich in lysine but was deficient in cereals. Therefore, the hydrophobic and aromatic amino acids in MBPHs-I were high, which could improve its antioxidant activity. According to the results, MBPHs-I was the best and most potent natural antioxidant and it can contribute to drug development and medical application.

Bioactive proteins and phytochemicals from legumes: Mechanisms of action preventing obesity and type-2 diabetes

The Fabaceae family of plants include a variety of seeds with multiple shapes, sizes, and colors; with a great diversity of bioactive compounds found in legume seeds. Legumes are an excellent source of protein, peptides and phytochemicals which are present in significant amounts. These bioactive compounds have been reported to reduce the risk of developing non-communicable diseases (NCD), such as obesity and type-2 diabetes. In this narrative review, we discuss the biological potential of bioactive compounds found in legumes and the health benefits associated with their consumption as an alternative approach in the management of NCD. Current extraction methods, characteristics of the bioactive compounds, and different in vitro and in vivo studies evaluating the bioactivity of legume bioactives are reviewed and discussed.

Enzymatic release of dipeptidyl peptidase-4 inhibitors (gliptins) from pigeon pea (Cajanus cajan) nutrient reservoir proteins: In silico and in vitro assessments

In silico and in vitro parameters were used to assess the potential of pigeon pea (Cajanus cajan) nutrient reservoir proteins as sources of dipeptidyl peptidase (DPP)-4 inhibitors. In silico, 40 pigeon pea proteins evaluated had 46% of amino acids associated with DPP-4 inhibition. After virtual hydrolysis, pepsin had the highest frequency of release and bioactivity of released DPP-4 inhibiting peptides, compared to papain and thermolysin. In vitro, thermolysin released the most active DPP-4 inhibitors. The protein hydrolysates contained similar amino acids but different particle sizes. Thus, the bioactivity patterns are attributable to the different nature and behavior of proteins/peptides under actual and virtual conditions. Using eight physicochemical variables, a random forest model with moderate prediction accuracy was developed for predicting DPP-4 inhibitory activity of papain hydrolysates. The findings demonstrate that proteins from pigeon pea are precursors of DPP-4 inhibitors, with potential use in formulating functional food for managing type 2 diabetes. PRACTICAL APPLICATIONS: The emerging use of in silico simulations to predict bioactivity of peptides can provide a framework to direct further wet lab assessments. This pattern can enhance focusing on factors relevant to the bioactive properties of interest. However, there is still limited evidence to confirm the reliability and accuracy of this tool. This study therefore provides insight into the practical use of in silico simulations to predict bioactivity of food peptides by assessing the factors relevant to the enzymatic release of dipeptidyl peptidase-4 inhibitors from pigeon pea seed storage proteins and validating the findings with wet lab assessment. This work also provides important information that can enhance the utilization of pigeon pea, which is an orphan crop, in developing functional food products for managing type 2 diabetes mellitus in developing countries.

Separation and Identification of Highly Efficient Antioxidant Peptides from Eggshell Membrane

The enzymatic hydrolysates (EHs) of the eggshell membrane (ESM) were obtained after incubating eggshell membrane in solutions prepared with Na₂SO₃ and alkaline protease combinations. The effects of enzyme species, enzyme dosage, Na₂SO₃ concentration, and hydrolysis time on the antioxidant activity of the ESM-EH were determined. Also, the correlation between the degree of hydrolysis (DH) and the antioxidant activity of ESM-EH was analyzed. The DH of ESM-EH showed a highly positive correlation with the reducing power (R² = 0.857) and total antioxidant activity (TAA) (R² = 0.876) and performed negative correlation with the Fe²⁺-chelating ability (R² = −0.529). The molecular weight distribution of the ESM-EH was determined by MALDI-TOF/MS. Cation exchange chromatography (Sephadex C-25) was used to isolate the ESM-EH and then the enzymatic hydrolysis fragment (EHF) was obtained. Among the five isolated fragments (F1~F5), fragment 3 (F3), which was composed of 28 polypeptides, showed the highest ability to quench ABTS• (2,2-azinobis-3-ethyl-benzothiazoline-6-sulfonic acid) (90.44%) and also displayed stronger TBARS (thiobarbituric acid– reactive substances) (58.17%) and TAA (303.82 µg /mL) than the ESM-EH. Further analysis of the 28 peptides in F3 identified using LC-MS/MS indicated that five peptides (ESYHLPR, NVIDPPIYAR, MFAEWQPR, LLFAMTKPK, MLKMLPFK) showed high water-solubility, biological activities, and antioxidant characteristics. Finally, the TAA of the synthetic peptide was verified, the synthetic peptides ESYHLPR and MFAEWQPR performed the best activity and have high potentials to be used as antioxidant agents in functional foods, pharmaceuticals, or cosmetics.

Optimization and Identification of Antioxidant Peptide from Underutilized Dunaliella salina Protein: Extraction, In Vitro Gastrointestinal Digestion, and Fractionation

DPPH• scavenging peptides (<3kDa) from underutilized Dunaliella salina protein were obtained by the following successive treatment, i.e., ultrasound extraction, simulated in vitro gastrointestinal digestion hydrolyzation, and membrane ultrafiltration classification. The optimal condition for ultrasound-assisted extraction was an ultrasound wave with 800 W of power treating a mixture of 60 mL of 1.0 mol L⁻¹ NaOH and 2 g algae powder for 15 min. A high correlation (r=0.8146) between DPPH• scavenging activity and yield of the intact peptides showed their antioxidant capacity. Simulated in vitro digestion assay resulted in excellent DPPH• scavenging activity of the total peptide, amounting to (86.5 ± 10.1)%, comparing with the nondigestion samples at (46.8 ± 6.5)%. After fractionation, the 500-1000 Da fraction exhibited the highest DPPH• scavenging activity (81.2 ± 4.0)%, increasing 1.5 times due to digestion. Then, the 500-1000 Da fraction was analyzed by RPLC-Q Exactive HF mass spectrometer, and 4 novel peptides, i.e., Ile-Leu-Thr-Lys-Ala-Ala-Ile-Glu-Gly-Lys, Ile-Ile-Tyr-Phe-Gln-Gly-Lys, Asn-Asp-Pro-Ser-Thr-Val-Lys, and Thr-Val-Arg-Pro-Pro-Gln-Arg, were identified. From these amino acid sequences, hydrophobic residues accounted for 56%, which indicated their high antioxidant property. The results indicated that underutilized protein of Dunaliella salina could be a potential source of antioxidative peptides through simulated in vitro gastrointestinal digestion.

Anti-Oxidative and Anti-Aging Activities of Porcine By-Product Collagen Hydrolysates Produced by Commercial Proteases: Effect of Hydrolysis and Ultrafiltration

To investigate methods for improving the processing of porcine waste, porcine skin was hydrolyzed using different commercially available proteases (Alcalase, Flavorzyme, Neutrase, Bromeline, Protamex, and Papain) under several optimal conditions. Following enzymatic hydrolysis, the collagen hydrolysates (CHs) were fractionated by molecular weight (3 kDa) via membrane ultrafiltration. The CHs were analyzed for physical properties (pH, protein recovery, free amino group content, molecular weight distribution, and amino composition) as well as for functional properties (antioxidant activities and anti-aging activities). Among the CHs, CHs hydrolyzed by Alcalase (CH-Alcalase) exhibited the highest degree of hydrolysis compared to other CHs. Both “CH-Alcalase” and “CH-Alcalase < 3 kDa” fractions showed a considerably high antioxidant activity and collagenase inhibition activity. Therefore, resulting bioactives have potential for development as antioxidants and anti-aging ingredients in the food, cosmetics, and pharmaceuticals, from animal by-products.