Antioxidant Activity Of Peptides Research Articles

Isolation and antioxidant activity of peptides from Chinese hairy tofu.

Hairy tofu is a famous Chinese snack that is made from soybeans and rich in various nutrients. In order to further explore the antioxidant peptides of hairy tofu hydrolysates, seven proteases were used to hydrolyze hairy tofu. The results of in vitro radical scavenging activity showed that hairy tofu hydrolysates obtained by pancreatin exhibited the highest antioxidant activity. After Sephadex G-25 gel filtration and reversed-phase high-performance liquid chromatography (RP-HPLC), 97 peptides were identified in the most antioxidant fraction using liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS). Among them, nine peptides were synthesized and their antioxidant activities were assessed using a H2 O2 -induced oxidative 293T cell model. Finally, four peptides (QCESHK, LAWNEGR, NLQGENEWDQK, and FTEMWR) at concentrations of < 50 μg/ml significantly decreased the malondialdehyde content compared with the model group, displaying in vivo antioxidant activity and low cytotoxicity. Overall, this research provided the choice of using hairy tofu peptides as antioxidant products in the pharmaceutical and food industries.

Exploring the novel antioxidant peptides in low-salt dry-cured ham: Preparation, purification, identification and molecular docking

Dry-cured ham is important source of bioactive peptides. In this study, the antioxidant activities of peptides and components from low and fully salted dry-cured hams were compared by peptidomics. And novel antioxidant peptides were identified and characterized. The results showed that the peptides (<3 KDa) extracted from low-salt dry-cured ham had higher antioxidant activity. Therefore, the antioxidant peptides in low-salt dry-cured ham were further characterized and the mechanism of their antioxidant activity was investigated. From the five candidate peptides selected, we found DWPDARGIWHND (DD12) to be highly stable, non-sensitizing, and non-toxic with the highest free radical scavenging activity. Molecular docking predicted that DD12 interacted with Keap1 through hydrogen-bond formation and hydrophobic interactions, suggesting that DD12 had good cellular antioxidant activity. DD12 peptide can bind to DPPH• and ABTS•+, resulting in strong free radical scavenging activity. Our findings support the development and application of natural antioxidant peptides in dry-cured ham.

HPLC purification of antioxidant and antibacterial peptides from a lichen "Parmotrema perlatum (Huds.) M. Choisy": Identification by LC-MS/MS peptide mass fingerprinting.

Parmotrema perlatum, a lichen belonging to the family Parmeliaceae, is well known for its culinary benefits and aroma used as a condiment in Indian homes is also known as the "black stone flower" or "kalpasi" in India. This research intends to analyze the antioxidant power of the crude extracts using four pH-based buffers solubilized proteins/peptides and RP-HPLC fractions of P. perlatum obtained by purification. The proteins that were extracted from the four different buffers were examined using LC-MS/MS-based peptide mass fingerprinting. When compared to the other buffers, the 0.1M of Tris-HCl buffer pH 8.0 solubilized proteins/peptides had the strongest antioxidant capacity. The sequential purification of the peptide was carried out by using a 3-kDa cut-off membrane filter and semipreparative RP-HPLC. Additionally, the purified fractions of the peptide's antioxidant activity were assessed, and effects were compared with those of the crude and 3kDa cut--off membrane filtrates. The peptide fractions were sequenced by LC-MS/MS, which reveals that fraction 2 from RP-HPLC with the sequence LSWFMVVAP has shown the highest antioxidant potential in comparison with other fractions which can serve as the potential natural antioxidant drug. Further, fraction 2 also showed antibacterial activity against the selected microorganisms.

Protein Hydrolysates from Fishery Processing By-Products: Production, Characteristics, Food Applications, and Challenges.

Fish processing by-products such as frames, trimmings, and viscera of commercial fish species are rich in proteins. Thus, they could potentially be an economical source of proteins that may be used to obtain bioactive peptides and functional protein hydrolysates for the food and nutraceutical industries. The structure, composition, and biological activities of peptides and hydrolysates depend on the freshness and the actual composition of the material. Peptides isolated from fishery by-products showed antioxidant activity. Changes in hydrolysis parameters changed the sequence and properties of the peptides and determined their physiological functions. The optimization of the value of such peptides and the production costs must be considered for each particular source of marine by-products and for their specific food applications. This review will discuss the functional properties of fishery by-products prepared using hydrolysis and their potential food applications. It also reviews the structure-activity relationships of the antioxidant activity of peptides as well as challenges to the use of fishery by-products for protein hydrolysate production.

Effects of cluster dextrin encapsulation on the properties and antioxidant stability of fractionated Riceberry protein hydrolysate powder prepared by bromelain

In this work, the biological properties of fractionated Riceberry bran protein hydrolysate obtained by ultrafiltration (URBPH) were evaluated and the possibility of using cluster dextrin to produce hydrolysate powder by spray-drying was investigated. Fractionation into peptides < 3 kDa was observed to improve antioxidant activity. URBPH < 3 kDa was then freeze-dried (FD-URBPH) and spray-dried (SD-URBPH) at different inlet air temperatures of 100–160 °C. The water solubility and antioxidant activity of FD-URBPH were higher than those of SD-URBPH. Nevertheless, encapsulation of hydrolysate with 10% cluster dextrin and an inlet temperature of 120 °C was also successful in maintaining protein qualities, which showed high 2,2′-azino-bis 3-ethylbenzthiazoline-6-sulfonic (ABTS•+) scavenging activity (89.14%) and water solubility index (92.49%) and low water activity (aw = 0.53). Moreover, encapsulation preserved the antioxidant activity of peptides during gastrointestinal digestion better than the free form. URBPH and its spray-dried microcapsules could be used as bioactive ingredients in functional drinks or foods.

Identification and action mechanism of novel antioxidative peptides from copra meal protein

This study aimed to identify novel antioxidant peptides from copra meal protein. The protein was enzymatically digested and properties of released peptides were predicted using in silico approach. The antioxidant activity of peptides was determined using ABTS and DPPH assays. Molecular docking and the isothermal titration calorimetry (ITC) were also used to explore the mechanism of antioxidant peptides scavenging free radicals. The results showed that peptides GMEEER and EEGER scavenged ABTS radical cation with IC50 values of 0.46 ± 0.067 mmol/L and 6.54 ± 0.14 mmol/L, and DPPH radicals with IC50 values of 6.98 ± 0.29 mmol/L and 11.06 ± 0.18 mmol/L. Hydrophobic interactions and hydrogen bonding were verified as the major driving force for scavenging of free radicals of peptides GMEEER and EEGER by molecular docking and ITC. Especially, the C-terminal residues Arg of two antioxidative peptides might play an important role in scavenging free radical. These findings revealed the antioxidant mechanism of copra meal protein and provided theoretical support for its high-value utilization.

Study on the antioxidant activity of peptides from soybean meal by fermentation based on the chemical method and AAPH-induced oxidative stress.

Preparation and antioxidant activities of soybean peptides using solid fermentation to decrease the content of trypsin inhibitor (TI) and antigen protein were investigated in this study. The results showed the optimal fermentation conditions were as follows: fermentation time 48 h, the ratio of material to solvent 1:2, inoculum size 12%, and the ratio of Lactic acid bacteria and Aspergillus oryzae 2:1. The hydrolysate was were divided into four components of <1, 1-3, 3-5, and >5 kDa by ultrafiltration based on molecular weight, and the <1 kDa peptides expressed the highest antioxidant activities. Meanwhile, the cell antioxidant activity of the <1 kDa soybean peptides was investigated using AAPH-induced erythrocyte hemolysis, which effectively inhibited erythrocyte hemolysis with the inhibit rate of 85.8% through inhibition of the ROS intracellular generation. In addition, soybean peptides could significantly restore the intracellular antioxidant enzymes (SOD, GSH-Px, and CAT) activities, as well as inhibited intracellular MDA generation and depletion of GSH. The intracellular antioxidant detoxifying mechanism of soybean peptides was associated with both non-enzymatic and enzymatic defense systems. According to this study, fermentation could effectively improve the antioxidant activities of soybean peptides.

Digestion-resistant whey peptides promote antioxidant effect on Caco-2 cells

Enteric endothelial cells are the first structure to come in contact with digested food and may suffer oxidative damage by innumerous exogenous factors. Although peptides derived from whey digestion have presented antioxidant potential, little is known regarding antioxidant pathways activation in Caco-2 cell line model. Hence, we evaluated the ability to form whey peptides resistant to simulated gastrointestinal digestive processes, with potential antioxidant activity on gastrointestinal cells and associated with sequence structure and activity. Using the INFOGEST method of simulated static digestion, we achieved 35.2% proteolysis, with formation of peptides of low molecular mass (<600 Da) evaluated by FPLC. The digestion-resistant peptides showed a high proportion of hydrophobic and acidic amino acids, but with average surface hydrophobicity. We identified 24 peptide sequences, mainly originated from β-lactoglobulin, that exhibit various bioactivities. Structurally, the sequenced peptides predominantly contained the amino acids lysine and valine in the N-terminal region, and tyrosine in the C-terminal region, which are known to exhibit antioxidant properties. The antioxidant activity of the peptide digests was on average twice as potent as that of the protein isolates for the same concentration, as evaluated by ABTS, DPPH and ORAC. Evaluation of biological activity in Caco-2 intestinal cells, stimulated with hydrogen peroxide, showed that they attenuated the production of reactive oxygen species and prevented GSH reduction and SOD activity increase. Caco-2 cells were not responsive to nitric oxide secretion. This study suggests that whey peptides formed during gastric digestion exhibit biological antioxidant activity, without the need for previously hydrolysis with exogenous enzymes for supplement application. The study’s primary contribution was demonstrating the antioxidant activity of whey peptides in maintaining the gastrointestinal epithelial cells, potentially preventing oxidative stress that affects the digestive system.

Identification and evaluation of antioxidant activity of bioactive casein-derived peptides during in vitro digestion and transepithelial transport in Caco-2 cells

Dairy products are important sources of bioactive (antibacterial, antithrombotic, antihypertensive, immunomodulatory, and antioxidative) peptides, that need to be released from the target proteins. In the present study, bovine milk casein protein was hydrolyzed by pancreatin and trypsin (4 and 24 h) to evaluate the hydrolyses efficiency (ninhydrin reaction); to elucidate the sequence of casein-derived peptides (SDS-PAGE, LC-ESI-TOF-MS); and to assess the peptides antioxidant activity (DPPH and ORAC), bioactivity in silico, bioaccessibility after in vitro digestion, and bioavailablility by transepithelial transport in Caco-2 cells. The hydrolysis degree increased with the incubation time, with evident degradation of casein-derived proteins into low molecular weight peptides (<5 kDa) after 4 and 24 h incubation. Pancreatin showed higher hydrolysis degree (91%) than trypsin (21%). An increase in antioxidant activity was observed with increasing incubation time, with higher antioxidant effect observed for trypsin derived peptides (47% reduction of free radicals; 32112 μM Trolox equivalents) than pancreatin derived peptides (15% reduction; 2862 μM Trolox equivalents). A total of 69 caseins derived peptides were identified after trypsin (33 peptides) and pancreatin (36 peptides) hydrolysis for 24 h; with 26 peptides released from β-casein, 21 from α-s1-casein, 15 from α-s2-casein, and 7 from k-casein hydrolysis. Some of these peptides were described as antioxidant, anti-inflammatory, and antihypertensive. After in vitro digestion 123 peptides were found in gastric (56 peptides), duodenal (43 peptides) and colonic (24 peptides) fraction; while five peptides were bioavailable by crossing the intestinal barrier, with increased peptides’ abundance after trypsin hydrolysis treatment.

Study of antioxidant properties of peptides, isolated from cows colostrum

Purpose. Evaluation of the antioxidant activity of peptides isolated from trypsin hydrolysate of cow colostrum. Materials and Methods. Based on the data obtained, it is possible to consider the possibility of using this peptide in the development of functional food products. However, it should be borne in mind that biologically active peptides have a number of disadvantages, in particular, low stability in the gastrointestinal tract, and can react with other biologically active substances in the composition of a food product and in the human body. Results. The antioxidant activity of peptides was determined by the DPPH method. Solutions of Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid) of known concentration were used as the standard solution. All spectrophotometric measurements were carried out using a CLARIOstar micro-tablet reader (BMG Labtech, Germany).Studies of the antioxidant activity of peptides with a known molecular weight and sequence of amino acids isolated from enzymatic hydrolysate of cow colostrum have been carried out. The functions of these peptides are not presented in the scientific and technical domestic and foreign literature. The antioxidant activity was determined by the DPPH method. It was found that the peptide with the amino acid sequence SQKKKNCPNGTRIRVPGPGP, consisting of 20 amino acids and having a molecular weight of 20 kDa, has an antioxidant activity of 0.128±0.008 mmol eq. Trolox/l, the antioxidant properties of the other peptides studied have not been established. It can be assumed that the antioxidant activity of peptides depends on the sequence and number of amino acids. Conclusion. Based on the data obtained, it is possible to consider the possibility of using this peptide in the development of functional food products. However, it should be borne in mind that biologically active peptides have a number of disadvantages, in particular, low stability in the gastrointestinal tract, and can react with other biologically active substances in the composition of a food product and in the human body.

Obtaining and Study of Peptide Compositions Based on Hydrolysates of Collagen-Containing Fish Raw Materials

Experimental studies of fish cutting waste—scales and skin were carried out, their general biochemical composition was studied, a high content of collagen was established, and elastin was noted, which accounted for 76–86% of the protein mass. Processes for the hydrolysis of secondary fish raw materials have been developed: fish scales and skin. Technological schemes have been developed and the influence of the conditions of thermal, enzymatic, enzymatic-thermal, electrochemical hydrolysis on the amino acid composition and molecular weight distribution (MWD) and antioxidant activity of peptides and proteins in the obtained hydrolysates has been studied. It has been established that the enzymatic and enzymatic-thermal method of hydrolysis of fish scales using the enzyme Alcalase 2.5 L and the electrochemical hydrolysis of the skin of cod, trout and herring made it possible to obtain protein hydrolysates with a protein content of 80–90%. At the same time, 91–98% of enzymatic hydrolysates from scales and 62%, 74% and 82.5% of electrochemically obtained hydrolysates from the skin of trout, herring, cod, respectively, account for the share of low-molecular peptides with a molecular weight of less than 10 kDa. The prospects of their use in functional foods and oil-containing products are noted.

Bioactive peptides of amaranth: isolation and determination of antioxidant and hypocholesterolemic properties

Hydrolysis of the amaranth protein isolate (Amaranthus hypochondriacus L., Voronezh variety) protein isolate by trypsin, papain and alkalase was carried out in order to obtain biologically active peptides with antioxidant and hypocholesterolemic activities. A high degree of protein hydrolysis was shown by trypsin during the first two hours, papain between three and four hours, and alkalase after four hours of hydrolysis. The rate of cleaved protein increased from the first two hours of hydrolysis from 40%, 30% and 15% to 78%, 70% and 60% when trypsin, papain, alkalase were applied, respectively. Maximum hydrolysis of the amaranth protein was observed after 6 h of proteolysis by all enzyme preparations. The molecular weights of the hydrolysis products of the amaranth protein after 2, 4 and 6 h of hydrolysis were determined. All hydrolysates showed a high content of polypeptides with molecular masses of 33 kDa, 18-23 kDa, 52-54 kDa, 40-54 kDa, 6.5-15 kDa. Short-chain peptides with molecular masses of 624 to 2817 Da were detected in the hydrolysates after 6 h of proteolysis. It was determined by capillary electrophoresis method that all protein hydrolysates after 6 h of hydrolysis contain amino acids (tyrosine, phenylalanine, alanine, leucine, valine, proline, alanine) responsible for antioxidant activity of peptides in the studied hydrolysates. The antioxidant activity of peptides in all hydrolysates of amaranth protein isolate was determined by ABTS cation radical reduction method for 6 min. Hypocholesterolemic activity of peptides was shown in protein hydrolysates by trypsin and papain.

Production and antioxidant activity of peptides from sturgeon head

The head is a significant, but typically unused, fish by-product. Here, we developed an industrially applicable new method to make head tissue peptides (HTPs) by autoclaving, blending and enzymatic hydrolysis of sturgeon head tissue. Four conditions were tested: head tissue autoclaved in distilled water (DW) and hydrolyzed with papain (DW-P) or papain and bromelain (DW-P + B), or head tissue autoclaved without DW and hydrolyzed with papain (WDW-P) or papain and bromelain (WDW-P + B). Among these conditions, DW-P + B resulted in the highest peptide yield, more peptides of <500 Da, and peptides with the highest antioxidant activity. Next, the same method produced sturgeon skin tissue peptide (STP) and skin collagen peptide (SCP) and the bioactivities were compared. The gross yield of HTP per fish was higher than that of STP and SCP because the sturgeon's head is ∼3 times heavier than its skin. The HTP contained more reactive oxygen species (ROS)-scavenging amino acids (Glx, His, Leu, Lys, Met, Phe, Tyr, Val) and showed significantly higher ABTS• scavenging activity than STP and SCP. The extracellular cell-protection and intracellular anti-ROS activities of HTP on the application of oxidative stress were similar to those of STP and SCP. Moreover, HTP showed high transparency and high safety (a low endotoxin level). All these features suggest that HTP is suitable for percutaneous applications. Extracellular oxidative stress promotes human skin aging; thus, HTP may be a novel, low-cost ingredient for anti-aging cosmetics. The present study will help to exploit zero industrial discards, resulting in blue transformation of by-products.

Liposome System for Encapsulation of Spirulina platensis Protein Hydrolysates: Controlled-Release in Simulated Gastrointestinal Conditions, Structural and Functional Properties

This study aimed to evaluate the physicochemical, structural, antioxidant and antibacterial properties of chitosan-coated (0.5 and 1% CH) nanoliposomes containing hydrolyzed protein of Spirulina platensis and its stability in simulated gastric and intestine fluids. The chitosan coating of nanoliposomes containing Spirulina platensis hydrolyzed proteins increased their size and zeta potential. The fourier transform infrared spectroscopy (FT-IR) test showed an effective interaction between the hydrolyzed protein, the nanoliposome, and the chitosan coating. Increasing the concentration of hydrolyzed protein and the percentage of chitosan coating neutralized the decreasing effect of microencapsulation on the antioxidant activity of peptides. Chitosan coating (1%) resulted in improved stability of size, zeta potential, and poly dispersity index (PDI) of nanoliposomes, and lowered the release of the hydrolyzed Spirulina platensis protein from nanoliposomes. Increasing the percentage of chitosan coating neutralized the decrease in antibacterial properties of nanoliposomes containing hydrolyzed proteins. This study showed that 1% chitosan-coated nanoliposomes can protect Spirulina platensis hydrolyzed proteins and maintain their antioxidant and antibacterial activities.

Electrospinning Pullulan to Nanoencapsulate Milk Derived Peptides

Background: Milk proteins are a source of bioactive peptides, which are concealed until released and activated. There is a growing interest and necessity for the use of biologically active milk protein-derived peptides with health-promoting properties in food. Despite several health benefits and functionalities, consumption of bioactive peptides through foods is poor due to their unfavorable flavour or bitter taste, low solubility, poor stability during processing and poor oral bioavailability. Electrospinning is an adaptable process for encapsulation since it does not involve severe temperature and requirement of chemicals for the preparation of encapsulate in the form of nanofibres. Methods: The peptide-loaded electrospun nanofibres are characterized for its surface morphology, encapsulation efficiency, zeta potential and interaction between wall material and peptides. In vitro release studies by dialysis bag technique and antioxidant property by DPPH method. Result: Pullulan at 10, 12 and 14% (w/w) concentrations was used for electrospinning of peptides. Scanning electron micrograph revealed the formation of clean beadfree peptides-loaded pullulan nanofibres at 12 and 14% concentrations. Encapsulation efficiency ranged from 73.00-86.00%. FTIR spectrum and XRD diffractograms showed the nonappearance of interactions between the functional groups of biopolymer pullulan and peptides in the electrospun nanofibres. The peptides from electrospun nanofibres showed sustained release. The antioxidant activity of peptides and those which are in the nanofibres was comparable. The physico-chemical and sensory analysis of milk fortified with peptide loaded nanofibres did not show noticeable difference.

Effect of Acid Whey in Combination with Sodium Ascorbate on Selected Parameters Related to Proteolysis in Uncured Dry-Fermented Sausages

The studies concern the effect of the addition of acid whey in combination with sodium ascorbate on selected parameters related to proteolysis in uncured dry-fermented sausages. Four sausage samples (with different additives: curing mixture (C); sea salt (S); sea salt and liquid acid whey (SAW); sea salt, liquid acid whey and sodium ascorbate (SAWA)) were taken at day 0, 7, 14 and 21 of ripening to assess basic physicochemical properties, thiobarbituric acid-reactive substances (TBARS), peptides content, antioxidant properties and biogenic amines content. It was indicated that the addition the acid whey caused greater acidification of fermented sausages during processing and significantly lower level of biogenic amines and lipid oxidation. At 21 days, the pH and water activity of sausages ranged from 4.74 ± 0.01 to 5.04 ± 0.04 and from 0.868 ± 0.002 to 0.875 ± 0.003, respectively. The synergistic effect of whey and sodium ascorbate was particularly noticeable in the reduction of lipid oxidation products and antioxidant activity of peptides. The results showed a beneficial effect of the addition of acid whey in combination with sodium ascorbate on the quality features of fermented sausage.

Effect of willow herb (Epilobium angustifolium L.) extract addition to canned meat with reduced amount of nitrite on the antioxidant and other activities of peptides.

The present study aimed to evaluate the effect of the addition of various amounts (50, 100, 150 and 1000 mg kg-1) of E. angustifolium L. extracts on the biological activity of peptides in canned meat with reduced amount of sodium nitrite and their stability during 180 days of storage (4 °C). The initial peptide data were collected by LC/MS. Antioxidant activities of peptide extracts were detected on the basis of ABTS˙*, FRAP, and iron(II) chelating activity in in vitro tests. A computational study (based on the BIOPEP-UWM database and INNOVAGEN, PeptideRanker and PROTPARAM tools) was also performed to assist in the interpretation of results. The addition of E. angustifolium L. extracts has a positive effect on the peptide profile and various biological activities, the results of which depend on the amount of the extract added to the meat product. However, it should be remembered that the differences between in silico and in vitro experimental environments necessitate further research to confirm the antioxidant behavior of canned meat products supplemented with E. angustifolium L. extract under physiological conditions. Other interactions between the peptide and the food matrix should also be considered as these can lead to chemical and structural modifications that can affect the bioavailability of the bioactive peptides.

Peptides derived from the gastrointestinal digestion of amaranth 11S globulin: Structure and antioxidant functionality

The relationship between structural and physicochemical properties and antioxidant activity of peptides from amaranth 11S-globulin was studied. Peptides AWEEREQGSR, TEVWDSNEQ, IYIEQGNGITGM and YLAGKPQQEH had the greatest in vitro activity (ORAC, HORAC). GDRFQDQHQ, HVIKPPSRA and KFNRPETT were the most active ones against Cu+2/H2O2-induced-LDL oxidation. In a cellular system (H2O2-induced-Caco2-TC7), TEVWDSNEQ, IYIEQGNGITGM, GDRFQDQHQ, LAGKPQQEHSGEHQ and KFNRPETT were the most effective in decreasing ROS, while the effects on SOD, GPx, and GSH were variable. To understand the structure–antioxidant activity relationships, the content of aromatic and acidic amino acids, the degree of hydrophobicity and the charge distribution on the accessible surface of peptides structures obtained by molecular dynamics were analysed. The low correlation between in vitro, ex vivo and cellular activities could be explained by the influence of physicochemical and structural properties on the interaction with complex systems (LDL/cells), peptide modifications and/or mechanisms other than direct ROS inhibition in the cells.

Investigation of S.limacinum microalgae digestibility and production of antioxidant bioactive peptides

Schizochytrium limacinum (S. limacinum) has potential as a high protein food ingredient. The digestibility of this protein was performed in the conditions of simulated stomach phase (with pepsin enzyme) and simulated small intestine phase (with α-chymotrypsin and trypsin). The whole hydrolysate was fractionated into various ranges of molecular weight cutoff (MWCO) by using ultrafiltration (UF) technique. Antioxidant activities of hydrolysate fractions were evaluated using direct free radical scavenging activity such as 2,2-diphenyl-1-picrylhydrazyl Radical (DPPH•) scavenging, activity, 2,2-azino-bis(3-ethylbenzthiazoline)-6-sulfonic acidradical cation (ABTS•+) sscavengin activity and reducing power activity. In addition, the protective effect of purified peptide against oxidation of low-density lipoprotein (LDL) was determined. The microalgae proteins were completely hydrolyzed by digestive enzymes and the enzymatic hydrolysis of proteins resulted in increased antioxidant activity of peptides. The peptide fraction F3 (MWCO = 5–10 kDa) presented the highest antioxidant activity out of all the methods described. The protein hydrolysates showed higher reducing power, radical scavenging capacity and significantly inhibited LDL oxidation. These results suggest that the enzymatic hydrolysates from S. limacinum can act as novel antioxidants in functional foods.

Antioxidant activities of peptides derived from mutton ham, Xuanwei ham and Jinhua ham

The aim of the study was to evaluate antioxidant activity of crude peptides with molecular weight less than 3 KDa extracted from Xuanwei ham, Jinhua ham and mutton ham. UPLC-Q-TOF-MS/MS was used for composition analysis of peptides and homologous protein matching. Further, crude peptide (<3 KDa) was purified using G-15 gel filtration chromatography, and the main antioxidant peptide identified. Analysis showed that mutton ham peptide (MHP) has the highest Fe2+ chelating ability, whereas Jinhua ham peptide (JHP) had the highest ABTS and DPPH free radical scavenging ability (P < 0.05). A total of 346, 203 and 296 peptides were identified in JHP, Xuanwei ham peptides (XHP) and MHP, respectively. Most of the peptides were derived from myosin, accounting for 21.97% in JHP, 18.72% in XHP, and 21.96% in MHP. Myosin, actin, myoglobin, troponin, tropomyosin and pyruvate kinase proteins were the main source of peptide differences in the three types of dry cured ham.