Development of antioxidant rich peptides from milk protein by microbial proteases and analysis of their effects on lipid peroxidation in cooked beef

Antioxidant peptides, the guardian of life from oxidative stress

Reactive oxygen species (ROS) are produced during oxidative metabolism in aerobic organisms. Under normal conditions, ROS production and elimination are in a relatively balanced state. However, under internal or external environmental stress, such as high glucose levels or UV radiation, ROS production can increase significantly, leading to oxidative stress. Excess ROS production not only damages biomolecules but is also closely associated with the pathogenesis of many diseases, such as skin photoaging, diabetes, and cancer. Antioxidant peptides (AOPs) are naturally occurring or artificially designed peptides that can reduce the levels of ROS and other pro-oxidants, thus showing great potential in the treatment of oxidative stress-related diseases. In this review, we discussed ROS production and its role in inducing oxidative stress-related diseases in humans. Additionally, we discussed the sources, mechanism of action, and evaluation methods of AOPs and provided directions for future studies on AOPs.

Enzymatically hydrolyzed sodium caseinate nanoparticles efficiently enhancing the solubility, stability, and antioxidant and anti-biofilm activities of hydrophobic Tanshinone IIA

Enzymatic hydrolysis has been validated as an appropriate strategy for improving the properties of natural protein. Here, we used enzymatic hydrolysis sodium caseinate (Eh NaCas) as a nano-carrier for enhancing the solubility, stability, and antioxidant and anti-biofilm activities of hydrophobic encapsulants. Tanshinone IIA (TA) was loaded into the hydrophobic regions of Eh NaCas by self-assembly, and the encapsulation efficiency could reach 96.54 ± 0.14% under an optimized host-guest ratio. After Eh NaCas packed, the TA-loaded Eh NaCas nanoparticles (Eh NaCas@TA) showed regular spheres, uniform particle size distribution and more optimal drug release. Moreover, the solubility of TA in aqueous solution increased over 2.4 × 10⁵ times, and the TA guest molecules displayed excellent stability under light and other harsh environments. Interestingly, the vehicle protein and TA exhibited synergistic antioxidant effects. Furthermore, Eh NaCas@TA forcefully restrained the growth and destroyed the biofilm construction of Streptococcus mutans compared to free TA, showing positive antibacterial activity. The establishment of these results demonstrated the feasibility and functionality of edible protein hydrolysates as nano-carriers for loading natural plant hydrophobic extracts.

Significance of whey protein hydrolysate on anti-oxidative, ACE-inhibitory and anti-inflammatory activities and release of peptides with biofunctionality: an in vitro and in silico approach

The study aimed to investigate potent antioxidant activities (ABTS assay, Hydroxyl free radical scavenging assay, and Superoxide free radical assay), ACE inhibitory activity, and anti-inflammatory activity in the WPC (whey protein concentrate) hydrolysate using Alcalase. The hydrolysis conditions (addition rate and incubation times) for peptide synthesis were also optimized using proteolytic activity. The generation of proinflammatory cytokines by lipopolysaccharide-treated murine macrophages was reduced when the protein hydrolysate concentration was low. In comparison to unhydrolyzed WPC, SDS-PAGE examination revealed no protein bands in WPC hydrolysates. Two-Dimensional (2D) gel electrophoresis did not show any protein spots. Using the 'In-solution trypsin digestion' approach, the trypsin digested protein samples were put into RPLC/MS for amino acid sequencing. Peptides were also identified using RPLC/MS on fractions of 3 and 10 kDa permeates and retentates. The MASCOT database was used to look up the raw masses of LC/MS. By comparing hydrolyzed whey protein to the BLASTp (NCBI), PIR, BIOPEP, and AHTPDB databases, novel antioxidative and ACE inhibitory peptides were reported.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13197-021-05282-3.

Antioxidant Activity Evaluation of Oviductus Ranae Protein Hydrolyzed by Different Proteases

As nutrition and a health tonic for both medicine and food, the protein content of Oviductus Ranae is more than 40%, making it an ideal source to produce antioxidant peptides. This work evaluated the effects of six different proteases (pepsin, trypsin, papain, flavourzyme, neutral protease and alcalase) on the antioxidant activity of Oviductus Ranae protein, and analyzed the relationship between the hydrolysis time, the degree of hydrolysis (DH) and the antioxidant activity of the enzymatic hydrolysates. The results showed that the antioxidant activity of Oviductus Ranae protein was significantly improved and the optimal hydrolysis time was maintained between 3-4 h under the action of different proteases. Among them, the protein hydrolysate which was hydrolyzed by pepsin for 180 min had the strongest comprehensive antioxidant activity and was most suitable for the production of antioxidant peptides. At this time, the DH, the DPPH radical scavenging activity, the absorbance value of reducing power determination and the hydroxyl radical scavenging activity corresponding to the enzymatic hydrolysate were 13.32 ± 0.24%, 70.63 ± 1.53%, 0.376 ± 0.009 and 31.96 ± 0.78%, respectively. Correlation analysis showed that there was a significant positive correlation between the hydrolysis time, the DH and the antioxidant activity of the enzymatic hydrolysates, further indicating that the hydrolysates of Oviductus Ranae protein had great antioxidant potential. The traditional anti-aging efficacy of Oviductus Ranae is closely related to the scavenging of reactive oxygen species, and its hydrolysates have better antioxidant capacity, which also provides support for further development of its traditional anti-aging efficacy.

Production and Characterization of Antioxidative Hydrolysates and Peptides from Corn Gluten Meal Using Papain, Ficin, and Bromelain

There has been a growing interest in developing natural antioxidants with high efficiency and low cost. Bioactive protein hydrolysates could be a potential source of natural and safer antioxidants. The objectives of this study were to hydrolyze corn gluten meal using three plant-derived proteases, namely papain, ficin, and bromelain, to produce antioxidative hydrolysates and peptides and to characterize the antioxidant performances using both chemical assays and a ground meat model. The optimum hydrolysis time for papain was 3 h, and for ficin and bromelain was 4 h. The hydrolysates were further separated by sequential ultrafiltration to 5 hydrolysate fractions named F1 to F5 from low molecular weight (MW) (<1 kDa) to high MW range (>10 kDa), which were further characterized for TPC, free radical scavenging capacity against DPPH and ABTS, and metal chelating activity. The fraction F4 produced by papain (CH-P4), F1 produced by ficin (CH-F1), and F3 produced by bromelain (CH-B3) showed the strongest antioxidant activity and yield, respectively. These three fractions were incorporated into ground pork to determine their inhibition effects on lipid oxidation during a 16-day storage period. The inhibition effect was enhanced with the addition of higher amount of hydrolysate (e.g., 1000 vs. 500 mg/kg). The CH-P4 reduced lipid oxidation in ground meat by as much as 30.45%, and CH-B3 reduced oxidation by 27.2% at the same level, but the inhibition was only 13.83% with 1000 mg/kg of CH-F1. The study demonstrated that CGM protein hydrolysates and peptides could be used as naturally derived antioxidant in retarding lipid oxidation and improving product storage stability.

In vitro and in vivo inhibition of maillard reaction products using amino acids, modified proteins, vitamins, and genistein: A review

Maillard reaction is known to result in loss of nutrients, particularly that of essential amino acids; decrease in digestibility and safety issues due to the development of toxic compounds. Maillard reaction products are also known to cause oxidation of tissues and inflammation, thus increasing the risk of cardiovascular diseases and diabetes. The aim of this review is to present a detailed information about the role of foodborne constituents as antibrowning agents to significantly reduce the harmful compounds like advanced glycation end products (AGEs) during food processing. This review includes strategies involving addition of amino acids, aromatic compounds, vitamins, modification of amino acids, and reducing sugars as antibrowning agents to reduce the AGEs. The role of Food borne functional ingredients such as catechin, epicathechin, luteolin, and ferulic acids as inhibitors of AGEs is also discussed. Among the naturally occurring inhibitors, genistein could be a crucial and safe agent to reduce reactive intermediates. PRACTICAL APPLICATIONS: Maillard reaction leads to changes in food color, protein functionality, protein digestibility, and loss of nutrient from foods. Maillard reaction products (MRPs) is also reported to be associated with various inflammatory conditions and may contribute to the progress of chronic diseases, including diabetes. It is hence necessary to reduce the MRPs, in both food and biological products, to offset this phenomenon. Among the strategies adopted till date, chemical agents could inhibit reactive carbonyl species and reactive oxygen species, but also are known to elicit serious side effects. Dietary flavonoids could be a very good inhibitor of MRPs both in biological and in food systems. It could be suggested that dietary flavonoids and isoflavones can be used as antibrowning agents in food and pharmaceutical industries particularly for targeted and sustained release of hypoglycemic drug in the intestines.

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.

Efficacy of antioxidant and antimicrobial activity of whole porcine blood hydrolysates and its fractions under in-vitro conditions

Protein hydrolysates were recovered from porcine blood hydrolysate (PBH) using enzymatic hydrolysis viz. alcalase, trypsin and papain. The PBH were ultra-filtered by using molecular weight cut off, these PBH and different fractions were evaluated for antioxidant and antimicrobial activity. The PBH and fractions were assessed for antioxidant efficacy viz. 2, 2-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid), 2, 2-diphenyl-1-picrylhydrazyl and Ferric reducing antioxidant power assay and antimicrobial activity by zone of inhibition assay. All antioxidant parameters assessed for inhibition activity were observed significantly (P < 0.05) higher for whole PBH whereas among fractions (5–10 kDa), (1–5 kDa) for all hydrolysates had comparatively higher antioxidant efficacy. The results showed that PBH obtained from trypsin and its fractions have highest antioxidant activities. The antimicrobial efficacy was also higher for whole PBH than their respective fractions; however, the zone of inhibition varied significantly (P < 0.05) among different fractions. Results revealed that among enzymes trypsin and alcalase could produce peptides with comparatively higher antimicrobial activity for all tested microbes than papain. The results concluded that porcine blood hydrolysates can be fractioned to get lower molecular weight peptides of interest; however, for addition of whole PBH in meat products or other use could be more useful with regards to its antioxidant, antimicrobial activity and economic production.

Fractionation and identification of novel antioxidant peptides from buffalo and bovine casein hydrolysates

Buffalo and bovine caseins were hydrolysed by alcalase and trypsin to produce novel antioxidant peptides. The casein hydrolysates were purified using ultrafiltration (UF) and further characterized by RP-HPLC. The fractions produced higher antioxidant activities were identified for their peptides using LC MS/MS. All UF-VI (MW<1kDa) fractions showed higher antioxidant activity. Hydrolysate produced by alcalase for buffalo casein (UF-VI with 54.84-fold purification) showed higher antioxidant activity than that obtained by trypsin. Trypsin hydrolysate contained high amount of hydrophobic amino acids while alcalase hydrolysate consisted mainly of Ser, Arg, Ala and Leu. The antioxidant peptides identified by LC MS/MS were RELEE, MEDNKQ and TVA, EQL in buffalo casein hydrolysates produced by trypsin and alcalase, respectively. Mechanism and reaction pathways of selected antioxidant peptides with ABTS were proposed. Conclusively, buffalo casein provided antioxidant peptides similar to bovine, suggesting that buffalo casein is a novel source of antioxidant.

Measurement of antioxidant activity with the thiobarbituric acid reactive substances assay

The thiobarbituric acid reactive substances (TBARS) assay is widely used to measure lipid oxidation and antioxidant activity in food and physiological systems. However, there has been no review (to our knowledge) that focuses exclusively on this test. This review presents an overview of the current use of the TBARS test in food and physiological systems, before looking at the various ways in which the assay is used in studies on antioxidant activity. As an antioxidant assay, the TBARS test may lack acceptable reproducibility, and long reaction times may preclude its adoption as a rapid screening method. Despite these potential limitations, there are features of the TBARS test that make it useful as a complement to popular screening tests such as Trolox equivalent antioxidant capacity. This review concludes with proposals for development of the TBARS test so that it can be used as a rapid and robust antioxidant assay.

Effect of boiling on the antidiabetic property of enzyme treated sheep milk casein

Aim:

Sheep milk-born bioactive peptides have been found to exhibit various physiological activities. The present work was designed with the aim to evaluate the effect of boiling on antidiabetic property of peptides derived from sheep milk caseinate on hydrolysis with three different proteases.

Materials and Methods:

In this investigation, casein prepared from raw and boiled sheep milk was hydrolyzed by three commercially available proteases (trypsin, pepsin, and chymotrypsin). These hydrolysates collected at different hydrolysis times (60, 120, 160, and 240 min) were assayed for their antidiabetic activity.

Results:

Among the three different enzyme hydrolysates, casein treated with chymotrypsin shows the highest antidiabetic activity among other enzymes. While the antidiabetic effect of raw milk-derived casein hydrolysates always exceeds than effect shown by boiled milk casein hydrolysates.

Conclusion:

The result obtained hence shows that the effect of boiling on the properties of bioactive peptides released during different enzyme digestion depends largely on the enzymatic formulation used and treatment conditions. Chymotrypsin treatment of raw casein yields peptides with maximum antidiabetic activity as compared to pepsin and trypsin. Moreover, the peptides produced after enzymatic treatment of boiled casein show reduced antidiabetic properties. Therefore, enzymatically treated raw milk casein hydrolysates may be used as effective nutritional supplements for diabetic patients, as it causes a significant inhibition of α-amylase activity.

Antimicrobial and radical scavenging properties of bovine collagen hydrolysates produced by Penicillium aurantiogriseum URM 4622 collagenase

A 2(3) full factorial design was used to identify the main effects and interactions of pH, collagen concentration and temperature on the degree of collagen hydrolysis (DH) by collagenase from Penicillium aurantiogriseum URM 4622. Increases in both pH and collagen concentration improved DH, and a positive interaction effect was observed for these variables. On the other hand, temperature had a negative main effect on DH. The maximum value of DH (4.65 μg/mL) was achieved at 7.5 mg/mL collagen concentration, pH 8.0 and 25 °C. The peptide profile showed several peptides with molecular weights lower than 2 kDa and exhibited antibacterial activity against Escherichia coli, Bacillus subtilis and Staphylococcus aureus. An antioxidant activity of 84.7 ± 0.24 % towards the radical ABTS• + was obtained with 50 mg/mL hydrolysates. This study demonstrated that collagen hydrolysed by P. aurantiogriseum URM 4622 collagenase possesses interesting antibacterial and antioxidant activities.

Characterization and potential use of cuttlefish skin gelatin hydrolysates prepared by different microbial proteases

Composition, functional properties, and in vitro antioxidant activities of gelatin hydrolysates prepared from cuttlefish skin were investigated. Cuttlefish skin gelatin hydrolysates (CSGHs) were obtained by treatment with crude enzyme preparations from Bacillus licheniformis NH1, Bacillus mojavensis A21, Bacillus subtilis A26, and commercial alcalase. All CSGHs had high protein contents, 74.3-78.3%, and showed excellent solubility (over 90%). CSGH obtained by alcalase demonstrated high antioxidant activities monitored by β-carotene bleaching, DPPH radical scavenging, lipid peroxidation inhibition, and reducing power activity. Its antioxidant activity remained stable or increased in a wide range of pH (1-9), during heating treatment (100°C for 240 min) and after gastrointestinal digestion simulation. In addition, alcalase-CSGH was incorporated into turkey meat sausage to determine its effect on lipid oxidation during 35 days of storage period. At 0.5 mg/g, alcalase-CSGH delayed lipid oxidation monitored by TBARS and conjugated diene up to 10 days compared to vitamin C. The results reveal that CSGHs could be used as food additives possessing both antioxidant activity and functional properties.

Isolation and identification of antioxidant peptides derived from whey protein enzymatic hydrolysate by consecutive chromatography and Q-TOF MS

To isolate and identify antioxidant peptides from enzymatically hydrolysed whey protein, whey protein isolate was hydrolysed by different protease (trypsin, pepsin, alcalase 2·4L, promatex, flavourzyme, protease N). The hydrolysate generated by alcalase 2·4L had the highest antioxidant activities on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, superoxide radicals and in a linoleic acid peroxidation system induced by Fe2+. The IC50 values of DPPH and superoxide radical scavenging activities of the hydrolysate decreased significantly (6·89 and 38·88%, respectively) after treatment with macroporous adsorption resin. Seven different peptides showing strong antioxidant activities were isolated from the hydrolysate using consecutive chromatographic methods including gel filtration chromatography and high-performance liquid chromatography. The molecular mass and amino acids sequences of the purified peptides were determined using a Quadrupole time-of-flight mass spectrometer (Q-TOF MS). One of the antioxidative peptides, Trp-Tyr-Ser-Leu, displayed the highest DPPH radical scavenging activity (IC50=273·63 μm) and superoxide radical scavenging activity (IC50=558·42 μm). These results suggest that hydrolysates from whey proteins are good potential source of natural antioxidants.

Radical Scavenging Activities and Lipid Peroxidation Inhibition of Okara Protein Hydrolysates Prepared with Proteases and Sequential UF

Okara protein isolate was hydrolyzed by two stages enzyme hydrolysis (Protamex+Flavourzyme, Pro+Fla ) and further separated by sequential ultrafiltration (UF) to four fractions (P1~P4). The 2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) scavenging activity of the P3 fraction (1kDa < MW < 3kDa) is 24.6 mmol trolox equivalent (TE)/g peptide and the inhibitory activity is 84.2% at 10 mg/mL. The hydroxyl radical scavenging activity is 85.4% at the same concentration. Pro+Fla-P3 was incorporated into ground beef to determine their effect on lipid oxidation during a 15-day storage period. Pro+Fla-P3 fraction at 500 μg/g significantly inhibited lipid oxidation by 20.8% and 18.2% at day 8 and 15 of storage. The concentration at 250 μg/g could not significantly inhibit lipid oxidation at 15 day. It suggests that okara protein hydrolysates could be developed and used to improve shelf-life of meat products.

Effects of peptide fractions with different isoelectric points from wheat gluten hydrolysates on lipid oxidation in pork meat patties

Wheat gluten hydrolysate (WGH) was fractionated on the basis of the amphoteric nature of sample peptides by preparative isoelectric focusing (autofocusing). Cooked pork patties were stored at 4 and 20 °C in the dark. WGH and autofocusing fractions suppressed the oxidation of lipids in the patties. The acidic (pI < 3.0) and basic (pI > 9.0) autofocusing fractions suppressed lipid oxidation in the cooked patties to a greater extent than other fractions and WGH. Each autofocusing fraction was evaluated by 1,1-diphenyl-2-picrylhydrazyl and hydroxyl radical scavenging activities, β-carotene bleaching, oxygen radical absorbance capacity, and Fe(2+) chelating assays; however, none of the in vitro assays predicted the suppressive effect of WGH on lipid oxidation in the cooked patties. These findings suggest that the microdistribution of peptides in food systems and their interaction with food matrix compounds play a significant role in the suppression of lipid oxidation in meat patties rather than radical scavenging activity.

Antioxidant Activity of Protein Hydrolysates from Aqueous Extract of Velvet Antler (Cervus elaphus) as Influenced by Molecular Weight and Enzymes

The crude protein hydrolysates from aqueous extract of velvet antler (AEVA) were prepared by simulated gastrointestinal digestion (SGI, pepsin-pancreatin) using pancreatin-pepsin, alcalase and neutrase. The resulting hydrolysates were separated by sequential ultrafiltration into four fractions. The antioxidant activities of peptide fractions were evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, ferric reducing antioxidant power (FRAP), 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging and Fe2+-chelating assays. Results showed that the hydrolysate prepared by SGI had a low degree of hydrolysis, which was significantly improved with altered proteases, such as pancreatin-pepsin and alcalase. Antioxidant activities of peptide fractions varied with molecular weight (MW) and the enzyme used. Generally, low-MW peptide fractions had higher ABTS radical scavenging activity and Fe2+-chelating ability, and high-MW peptide fractions were more effective in DPPH radical scavenging activity and reducing power.

Antioxidant, antihypertensive and antimicrobial properties of ovine milk caseinate hydrolyzed with a microbial protease

BACKGROUND

Bioactive peptides might be released from precursor proteins through enzymatic hydrolysis. These molecules could be potentially employed in health and food products. In this investigation, ovine milk caseinate hydrolysates obtained with a novel microbial protease derived from Bacillus sp. P7 were evaluated for antioxidant, antimicrobial, and angiotensin I-converting enzyme (ACE)-inhibitory activities.

RESULTS

Antioxidant activity measured by the 2,2'-azino-bis-(3-ethylbenzothiazoline)-6-sulfonic acid method increased with hydrolysis time up to 2 h, remaining stable for up to 4 h. Hydrolysates showed low 2,2-diphenyl-1-picrylhydrazyl radical-scavenging abilities, with higher activity (31%) reached after 1 h of hydrolysis. Fe(2+) -chelating ability was maximum for 0.5 h hydrolysates (83.3%), decreasing thereafter; and the higher reducing power was observed after 1 h of hydrolysis. ACE-inhibitory activity was observed to increase up to 2 h of hydrolysis (94% of inhibition), declining afterwards. 3 h hydrolysates were shown to inhibit the growth of Bacillus cereus, Corynebacterium fimi, Aspergillus fumigatus, and Penicillium expansum.

CONCLUSION

Ovine caseinate hydrolyzed with Bacillus sp. P7 protease presented antioxidant, antihypertensive, and antimicrobial activities. Hydrolysis time was observed to affect the evaluated bioactivities. Such hydrolysates might have potential applications in the food industry.