Antioxidant peptides derived from lactoferrin and their applications

Abstract

The present invention belongs to the field of biomedicine, and specifically relates to antioxidant peptides derived from lactoferrin and their applications. The antioxidant peptides derived from lactoferrin have an amino acid sequence shown in any one of SEQ ID NO: 1 to 99, and have antioxidant effects, and can be used in the preparation of antioxidant products, such as being used as active ingredients in foods, cosmetics or health products.

Description

Technical Field

[0001] The present invention belongs to the field of biomedicine, and particularly relates to antioxidant peptides derived from lactoferrin and their applications. Background Art

[0002] With the development of free radical biology and medicine, the research on free radicals and antioxidants has attracted increasing attention. Reactive oxygen species are by-products of the physiological metabolism of human cells, including hydroxyl radicals, superoxide anion radicals, singlet oxygen, hydrogen peroxide, etc., and will be promptly scavenged by the cellular antioxidant system (Guo Y, Zhang T, Jiang B, et al. The effects of an antioxidative pentapeptide derived from chickpea protein hydrolysates on oxidative stress in Caco-2 and HT-29 cell lines [J]. Journal of Functional Foods, 2014, 7: 719-726.). Under certain circumstances, the excessive accumulation of free radicals can trigger oxidative stress reactions in the body, causing oxidative damage to biological macromolecules such as proteins, lipids, DNA, etc. within cells, thereby accelerating the aging of the body and triggering various diseases such as neurodegenerative diseases, atherosclerosis, chronic inflammation, and cancer (García-Nebot M J, Recio I, Hernández-Ledesma B. Antioxidant activity and protective effects of peptide lunasin against oxidative stress in intestinal Caco-2 cells [J]. Food and Chemical Toxicology, 2014, 65: 155-161.). Research has shown that the intake of antioxidants in vitro can scavenge excessive free radicals in the body and reduce the level of oxidative stress in the body, and can play a role in preventing and even treating certain diseases (He R, Ju X, Yuan J, et al. Antioxidant activities of rapeseed peptides produced by solid state fermentation [J]. Food Research International, 2012, 49(1): 432-438.). Oxidation is also one of the important reasons for food deterioration, reducing nutritional value and even producing harmful substances. Therefore, antioxidants are in wide demand in the fields of health products, food, medicine, and cosmetics.Due to the potential harm of long-term intake of synthetic antioxidants to human health, natural food-derived antioxidants have gained increasing popularity (Liu C, Ren D, Li J, et al. Cytoprotective effect and purification of novel antioxidant peptides from hazelnut (C. heterophylla Fisch) protein hydrolysates [J]. Journal of Functional Foods, 2018, 42: 203-215.). Among natural antioxidants, antioxidant peptides derived from animal and plant food proteins have received extensive attention due to their low molecular weight, high activity, easy absorption, colorless, odorless, and side-effect-free characteristics (Mahgoub S, Alagawany M, Nader M, et al. Recent development in bioactive peptides from plant and animal products and their impact on the human health [J]. Food Reviews International, 2021: 1-26.). There are many types of antioxidant peptides, with different molecular sizes and solubilities, providing more options for their development and utilization.

[0003] The main ways to obtain antioxidant peptides are as follows: First, screening directly from animal and plant cell lysates; Second, using animal and plant proteins as raw materials, selecting appropriate enzymes for hydrolysis, and using methods such as ultrafiltration and chromatography to separate and purify polypeptides of a certain molecular weight, and measuring the antioxidant activity of the corresponding separated components; After clarifying the sequence of antioxidant peptides, a large number of antioxidant peptides can be obtained through separation, purification or synthesis techniques; Third, using bioinformatics methods to analyze proteins with known sequences in animals and plants, predicting highly active polypeptide fragments, and synthesizing them by chemical synthesis methods for activity verification (Research status of antioxidant peptides.).

[0004] Lactoferrin (LF) is a non-heme iron-binding glycoprotein secreted by mammalian mucosal epithelial cells (Mayeur S, Spahis S, Pouliot Y, et al. Lactoferrin, a pleiotropic protein in health and disease [J]. Antioxidants & redox signaling, 2016, 24(14): 813-836.). With a molecular weight of approximately 80 kDa, it is widely present in tears, saliva, sweat, gastrointestinal fluids, cow's milk, and human colostrum and is considered one of the basic elements of the human and anti-infection defense systems (Park J H, Park G T, Cho I H, et al. An antimicrobial protein, lactoferrin exists in the sweat: proteomic analysis of sweat [J]. Experimental Dermatology, 2011, 20(4): 369-371. & Masson P, Heremans J F, Prignot J. Immunohistochemical localization of the iron-binding protein lactoferrin in human bronchial glands [J]. Experientia, 1965, 21(10): 604-605.). It has been reported that LF has biological functions such as antibacterial, antiviral, anti-parasitic, anti-cancer, antioxidant, anti-allergic, anti-inflammatory, and immunomodulatory effects (Zhang Enpeng. Research on the design of bovine lactoferrin-derived peptides and their expression in Pichia pastoris [D]. Jiangsu University, 2019. & Fan F, Shi P, Liu M, et al. Lactoferrin preserves bone homeostasis by regulating the RANKL / RANK / OPG pathway of osteoimmunology [J]. Food & Function, 2018, 9(5): 2653-2660.).Due to the benefits of LF, it is often added to various products such as infant formula, health products, cosmetics, pet care supplements, beverages, fermented milk, chewing gum, and toothpaste. It helps regulate iron absorption and protects the neonatal gastrointestinal tract from infection (Brock J H. Lactoferrin in human milk: its role in iron absorption and protection against enteric infection in the newborn infant[J]. Archives of Disease in Childhood, 1980, 55(6): 417.), and is used to enhance the body's immunity (Wang B, Timilsena Y P, Blanch E, et al. Lactoferrin: Structure, function, denaturation and digestion[J]. Critical Reviews in Food Science and Nutrition, 2019, 59(4): 580-596.). At the same time, many have been proven to have activities exceeding those of the whole protein and possess multiple active functions. For example, LF polypeptides have angiotensin-converting enzyme inhibitory activity, antioxidant and anti-inflammatory activities (Ruiz-Giménez P, Salom J B, Marcos J F, et al. Antihypertensive effect of a bovine lactoferrin pepsin hydrolysate: Identification of novel active peptides[J]. Food Chemistry, 2012, 131(1): 266-273. & Gu Y, Wu J. Bovine lactoferrin-derived ACE inhibitory tripeptide LRP also shows antioxidative and anti-inflammatory activities in endothelial cells[J]. Journal of Functional Foods, 2016, 25: 375-384.).Although studies have shown that the degradation products of lactoferrin retain biological activities such as antioxidant activity, the process of preparing bioactive peptides by enzymatic hydrolysis is complex, time-consuming, costly, the product composition is uneven, and it is difficult to control the quality of different batches, making it difficult to conduct in-depth research on its mechanism of action (Zhang Qiang, Li Weihua. Research status of antioxidant peptides [J]. Food and Fermentation Industries, 2021, 47(2): 298-304.). Therefore, it is necessary to use bioinformatics analysis to supplement the traditional methods for studying antioxidant peptides. However, screening antioxidant peptides based on computer simulation, especially antioxidant peptides derived from lactoferrin, has not been reported. Summary of the Invention

[0005] The present invention adopts a bioinformatics method to design a lactoferrin peptide library based on an overlapping peptide library, and uses AnOxPePred-1.0 to predict and screen antioxidant peptides with high activity, which can be used as additives for food, cosmetics or health products. Among them, the traditional method of separating and purifying bioactive peptides from proteins is abandoned, and a bioinformatics method is adopted for design, thus greatly saving the experimental time cost and money cost. Aiming at the lack of effective discovery means for antioxidant active peptides in the traditional method, the method for high-throughput screening of polypeptides with antioxidant activity involved in the present invention is simple and effective, with unique advantages. The antioxidant peptides screened in the present invention are derived from the lactoferrin sequence, achieving the goals of good biocompatibility, greenness and safety of the source.

[0006] In order to achieve the above object, the technical solution provided by the present invention is as follows:

[0007] The present invention provides antioxidant peptides derived from lactoferrin, and the amino acid sequence is shown as any one of SEQ ID NO: 1 to 99.

[0008] Preferably, the amino acid sequence is shown as any one of SEQID NO: 1-2, SEQID NO.8, SEQID NO.10, SEQID NO.15, SEQID NO.17, SEQID NO:23-26, SEQID NO.34, SEQID NO.37, SEQID NO.40, SEQID NO.43, SEQID NO.48, SEQID NO.50, SEQID NO:53-57, SEQID NO.61, SEQID NO.64-65, SEQIDNO.68, SEQID NO:71-73, SEQID NO.75, SEQID NO.77, SEQID NO.79, SEQID NO:85-88, SEQIDNO:92-94, SEQID NO.96 and SEQID NO:98-99.

[0009] More preferably, its amino acid sequence is as shown in SEQ ID NO.1, SEQ ID NO.23, SEQ ID NO.24, SEQ ID NO.55, SEQ ID NO.61, SEQ ID NO.65, SEQ ID NO.68, SEQ ID NO.73, SEQ ID NO.79 or SEQ ID NO.98. Even more preferably, its amino acid sequence is as shown in any one of SEQ ID NO.24, SEQ ID NO.55, and SEQ ID NO.73.

[0010] The present invention also provides nucleic acids encoding the antioxidant peptides described above, expression vectors containing the nucleic acids, and recombinant cells containing the expression vectors.

[0011] The present invention also provides the use of the antioxidant peptides described above or their encoding nucleic acids in the preparation of antioxidant products.

[0012] Preferably, the products refer to foods, cosmetics or health products, and the antioxidant peptides are used as active ingredients or additives.

[0013] The present invention innovatively adopts an overlapping peptide library to design a lactoferrin peptide library, realizes the establishment of a lactoferrin peptide library for the entire sequence, saves time and cost, and improves the accuracy of the sequence composition of the hydrolysis products, which is original in the field of bioinformatics bioactive peptides. Among them, by innovatively adopting the AnOxPePred-1.0 server to predict and screen lactoferrin antioxidant peptides with high activity, a high-throughput screening method for lactoferrin antioxidant peptides is realized, saving funds and manpower, improving efficiency, and being original in the field of bioactive peptides. The characteristics of the present invention are the existence of specific amino acid sequences, which contain cysteine. These innovative peptides can well scavenge free radicals to improve antioxidant activity and belong to natural antioxidants with good safety.

[0014] Specifically, the innovative peptides provided by the present invention are detected to have excellent antioxidant activity. Under the measurement conditions of the present invention, their DPPH free radical scavenging ability and ABTS free radical scavenging ability are respectively close to or better than those of glutathione and carnosine. Detailed implementation methods

[0015] Combined with the implementation examples, the present invention is further elaborated. Unless otherwise specified, the reagents and instruments used in the following examples are all commercially available products.

[0016] Example 1 Design of a lactoferrin peptide library based on an overlapping peptide library and rapid screening method

[0017] I. Establishment of a lactoferrin peptide library

[0018] (1) Query and obtain the amino acid sequence of lactoferrin in the UniProt protein database;

[0019] (2) Design 1398 overlapping polypeptide segments of length 11 from the above amino acid sequence by the overlapping peptide library method, with adjacent peptide segments overlapping by 10 amino acids.

[0020] II. Bioinformatics prediction of antioxidant activity sequences

[0021] (1) Group the above 1398 peptide sequences, with 50 in each group, for a total of 28 groups, and submit them to the AnOxPePred-1.0 server (AnOxPePred-1.0-Services-DTU Health Tech). Set the polypeptide length range to 2 - 30 amino acids and use the peptide mode to obtain the free radical scavenger (FRS) or chelation (CHEL) scores of the above predicted peptides;

[0022] (2) According to the FRS score threshold ≥ 0.45 predicted in step (1), screen out 179 peptide sequences;

[0023] (3) Connect x peptide sequences with continuously overlapping partial amino acid sequences in step (2) into a long peptide chain composed of y amino acid residues. The connection method is to connect the C-terminus of the nth amino acid sequence to the non-overlapping sequence of the (n + x - 1)th amino acid sequence to obtain 53 peptide sequences;

[0024] (4) Submit the peptide sequences obtained in step (3) to the AnOxPePred-1.0 server according to step (1) to obtain the FRS scores of the predicted peptides, and the results are shown in Table 1.

[0025] Table 1. FRS scores of 53 peptides

[0026]

[0027]

[0028] (5) Based on the new sequences SEQ ID NO.1, SEQ ID NO.2, SEQ ID NO.3, and SEQ ID NO.10 obtained in step (4), add partial amino acid residues at the N-terminus to obtain sequences SEQ ID NO.26, SEQ ID NO.27, SEQ ID NO.28, and SEQ ID NO.29, and submit them to the AnOxPePred-1.0 server according to step (1) to obtain the FRS scores of the predicted peptides, and the results are shown in Table 2;

[0029] Table 2. FRS scores of 4 peptides

[0030] SEQ ID NO. Peptide sequence Length FRS score 54 CVPNSKEKYYGYTGAFRCL 19 0.60702 55 CACSSREPYFGYSGAFKCLQ 20 0.58787 56 CLAKLGGRPTYEEYLGTEYVTA 22 0.56280 57 ADALNLDGGYIYTAGKCG 18 0.53777

[0031] (6) According to the CHEL score threshold predicted in step (1) ≥ 0.25, 97 peptide sequences were screened out;

[0032] (7) The peptide sequences obtained in step (5) were ligated into peptide chains according to the method in step (3) to obtain 42 peptide sequences;

[0033] (8) The peptide sequences obtained in step (7) were submitted to the AnOxPePred-1.0 server according to step (1) to obtain the CHEL scores of the predicted peptides. The results are shown in Table 3.

[0034] Table 3. CHEL scores of 42 peptides

[0035]

[0036]

[0037] Example 2 Verification of the activity of antioxidant peptides

[0038] I. Synthesis of antioxidant peptides

[0039] According to the predicted and screened lactoferrin antioxidant peptide sequences in Example 1, GenScript Biotech Corporation was commissioned for synthesis.

[0040] II. Verification of the activity of antioxidant peptides

[0041] (1) DPPH radical scavenging ability

[0042] Preparation of related reagents:

[0043] 1) DPPH solution: 0.2 mM (dissolved in absolute ethanol).

[0044] 2) Polypeptide solution: Custom synthesized from GenScript Biotech Corporation. The lyophilized powder was dissolved in pure water.

[0045] Experimental protocol:

[0046] Sample#1

[0047] 100 μL of polypeptide solutions with different concentrations were respectively pipetted and added to 100 μL of 0.2 mM DPPH ethanol solution. After shaking well, they were placed at room temperature in the dark for 30 min. The absorbance At at 517 nm was measured. At the same time, the absorbance Ar of 100 μL of polypeptide solution + 100 μL of ethanol solution at 517 nm was measured, and the absorbance A0 of 100 μL of DPPH solution + 100 μL of ethanol at 517 nm was measured. Three parallels were designed for the same measurement. The results are shown in Tables 4 and 5.

[0048] DPPH radical scavenging rate (%) = [1 - (A s - A b ) / A c × 100

[0049] A c : Absorbance value of 100 μL absolute ethanol + 100 μL DPPH solution; A s : Absorbance value of 100 μL sample solution + 100 μL DPPH solution; A b : Absorbance value of 100 μL sample solution + 100 μL absolute ethanol.

[0050] Experimental results:

[0051] DPPH radical is a stable nitrogen-centered purple radical, and antioxidants can reduce DPPH radical to a yellow compound. The reason for this phenomenon is that DPPH radical can accept an electron or a hydrogen atom to form a stable diamagnetic molecule. In this study, 99 polypeptides and GSH were uniformly assayed for DPPH radical scavenging activity to evaluate their antioxidant activity in various aspects. The results are shown in Table 4. For 99 lactoferrin antioxidant peptides, when the concentration was 0.5 mg / mL, their DPPH radical scavenging rates were 18.69% - 94.64%. It was also found that polypeptides containing Cys amino acid residues had relatively high DPPH radical scavenging activity, especially the polypeptide SEQ ID NO.55 containing 3 Cys amino acid residues. For 41 polypeptides SEQ ID NO:1 - 2, SEQ ID NO.8, SEQ ID NO.10, SEQ ID NO.15, SEQ ID NO.17, SEQ ID NO:23 - 26, SEQ ID NO.34, SEQ ID NO.37, SEQ ID NO.40, SEQ ID NO.43, SEQ ID NO.48, SEQ ID NO.50, SEQ ID NO:53 - 57, SEQ ID NO.61, SEQ ID NO:64 - 65, SEQ ID NO.68, SEQ ID NO.71 - 73, SEQ ID NO.75, SEQ ID NO.77, SEQ ID NO.79, SEQ ID NO:85 - 88, SEQ ID NO:92 - 94, SEQ ID NO.96 and SEQ ID NO.98 - 99 containing Cys amino acid residues, their DPPH radical scavenging activity IC 50It is 0.027 - 0.175 mg / mL (see Table 5). From these results, it can be seen that in addition to the number of Cys amino acid residues having a high impact on the DPPH radical scavenging rate, the position of the Cys amino acid residue also has a great influence on the DPPH radical scavenging activity. Generally, among the above 41 polypeptides, when the Cys amino acid residue is at the N-terminus of the peptide, such as SEQ ID NO.25, SEQ ID NO.48, SEQ ID NO.56, SEQ ID NO.68, and SEQ ID NO.86 containing one Cys amino acid residue, and SEQ ID NO.2, SEQ ID NO.54, SEQ ID NO.61, and SEQ ID NO.79 containing two Cys, they have relatively high DPPH radical scavenging activity. Structurally, their strong antioxidant activity may be related to the Cys residue at the N-terminus of the peptide chain. Cys is a sulfur-containing amino acid, and the sulfhydryl group (-SH) in the side chain is a highly reactive group, showing weak acidity (pK = 8.4) and being prone to losing protons. Therefore, Cys is easy to couple with the electrons in DPPH. In contrast, the DPPH radical scavenging activity of polypeptides with Cys amino acid residues at the C-terminus and in the middle of the sequence is relatively low. In addition, the DPPH radical scavenging activity of GSH is 0.032 mg / mL. Obviously, in terms of DPPH radical scavenging activity, GSH has very high activity. The DPPH radical scavenging activities of SEQ ID NO.1, SEQ ID NO.2, SEQ ID NO.48, SEQ ID NO.55, SEQ ID NO.61, SEQ ID NO.68, and SEQ ID NO.79 are comparable to that of GSH. The activities of SEQ ID NO.2, SEQ ID NO.48, SEQ ID NO.55, and SEQ ID NO.86 are even higher than that of GSH, and there is no statistically significant difference. It can be clearly seen that the above polypeptides and GSH all have a common Cys amino acid residue, and due to the presence of the sulfhydryl group of the Cys amino acid residue, the ability to directly react with free radicals (Jiang H, Tong T, Sun J, et al. Purification and characterization of antioxidative peptides from roundscad (Decapterus maruadsi) muscle protein hydrolysate [J]. Food Chemistry, 2014, 154: 158 - 163.), so this type of polypeptide has strong DPPH radical scavenging activity. In addition, for polypeptides without Cys amino acid residues, such as the remaining 58 peptides, they show low DPPH radical scavenging activity.Therefore, not only the amino acid residue composition, such as Cys amino acid residues, but also the position where the active amino acid residues are located, such as the C-terminus or N-terminus, have a great influence on the DPPH free radical scavenging activity of the polypeptide.

[0052] Table 4. Scavenging ability of 0.5 mg / mL polypeptide against DPPH free radicals

[0053]

[0054]

[0055]

[0056] Table 5. IC 50 value of the scavenging ability of polypeptides containing Cys amino acid residues and glutathione against DPPH free radicals

[0057] Sample <![CDATA[IC 50 Value (mg / mL)]]> Sample <![CDATA[IC 50 Value (mg / mL)]]> Glutathione 0.032 SEQ ID NO.57 0.098 SEQ ID NO.1 0.039 SEQ ID NO.61 0.039 SEQ ID NO.2 0.029 SEQ ID NO.64 0.145 SEQ ID NO.8 0.041 SEQ ID NO.65 0.146 SEQ ID NO.10 0.147 SEQ ID NO.68 0.040 SEQ ID NO.15 0.135 SEQ ID NO.71 0.156 SEQ ID NO.17 0.152 SEQ ID NO.72 0.150 SEQ ID NO.23 0.088 SEQ ID NO.73 0.124 SEQ ID NO.24 0.062 SEQ ID NO.75 0.175 SEQ ID NO.25 0.046 SEQ ID NO.77 0.091 SEQ ID NO.26 0.090 SEQ ID NO.79 0.040 SEQ ID NO.34 0.088 SEQ ID NO.85 0.092 SEQ ID NO.37 0.092 SEQ ID NO.86 0.029 SEQ ID NO.40 0.087 SEQ ID NO.87 0.078 SEQ ID NO.43 0.090 SEQ ID NO.88 0.080 SEQ ID NO.48 0.030 SEQ ID NO.92 0.079 SEQ ID NO.50 0.080 SEQ ID NO.93 0.101 SEQ ID NO.53 0.094 SEQ ID NO.94 0.110 SEQ ID NO.54 0.044 SEQ ID NO.96 0.121 SEQ ID NO.55 0.027 SEQ ID NO.98 0.041 SEQ ID NO.56 0.096 SEQ ID NO.99 0.087

[0058] (2) ABTS free radical scavenging ability

[0059] Preparation of related reagents:

[0060] 1) ABTS solution: 7 mM. Weigh 19.2 mg of ABTS and dissolve it in 5 mL of pure water.

[0061] 2) Potassium persulfate solution: 140 mM. Weigh 189 mg of potassium persulfate and dissolve it in 5 mL of pure water.

[0062] 3) ABTS stock solution: Mix 5 mL of ABTS solution and 5 mL of potassium persulfate solution, and let it stand overnight for 16 h at room temperature in the dark to form the ABTS stock solution.

[0063] 4) Polypeptide solution: Custom synthesized from GenScript Biotech Corporation, and the lyophilized powder is dissolved in pure water.

[0064] Experimental protocol:

[0065] Sample#1

[0066] 1) Dilute the above ABTS stock solution with pure water to a working solution, and require its absorbance at a wavelength of 734 nm to be 0.7 ± 0.02.

[0067] 2) Pipette 100 μL of polypeptide solutions with different concentrations respectively, add 100 μL of ABTS working solution, shake for 1 - 2 min, place it at 37 °C for 10 min, and then measure the absorbance value A s at 734 nm. Use (100 μL of ABTS working solution + 100 μL of pure water) as the blank absorbance A c。The absorbance of the uniformly mixed solution of 100 μL of polypeptide solution + 100 μL of pure water is A b 。Three parallels were designed for the same determination. The results are shown in Tables 6 and 7

[0068] ABTS radical scavenging rate (%) = [1 - (A s - A b ) / A c × 100

[0069] A s : The absorbance of adding 100 μL of sample solution to 100 μL of ABTS solution; A b : The absorbance of adding 100 μL of sample solution to 100 μL of distilled water; A c : The absorbance of adding 100 μL of ABTS solution to 100 μL of distilled water

[0070] Experimental results:

[0071] In the reaction system, ABTS will be oxidized to generate ABTS radicals, which are stable and water-soluble radicals, showing blue-green color and having the maximum absorbance value at 734 nm. The reaction of ABTS radicals with antioxidants can fade the characteristic color of the former, thereby reducing the absorbance value. Under the same conditions, the antioxidant activity of biological samples is proportional to the degree of decrease in the absorbance value of the reaction solution. The ABTS radical scavenging rates of different sequence lactoferrin polypeptides are shown in Table 6. At a concentration of 0.5 mg / mL, their ABTS radical scavenging rates are 8.66% - 99.96%. It was also found that polypeptides containing Cys amino acid residues have relatively high ABTS radical scavenging activity. For 41 polypeptides containing Cys amino acid residues, their ABTS radical scavenging rates are 80.99% - 99.96%. Among them, their IC 50 is 0.020 - 0.067 mg / mL. At the same time, the ABTS radical scavenging activity of the positive control carnosine is 1.244 mg / mL. Obviously, the ABTS radical scavenging activity IC 50The values are significantly lower than those of carnosine. Studies have shown that the reaction rate of ABTS free radicals with amino acids is mainly determined by whether the amino acid side chain has unstable hydrogen atoms, and is related to the pH of the solution and the concentration of the sample. Under the same reaction conditions, the activity of several amino acids in scavenging free radicals is ranked as follows: Cys>Trp>Tyr>His (Aliaga C, Lissi E A. Reactions of the radical cation derived from 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS·+)with aminoacids. Kinetics and mechanism[J]. Canadian Journal of Chemistry, 2000, 78(8):1052-1059.). Consistent with the above research conclusions, lactoferrin polypeptides with strong ABTS free radical scavenging ability all contain Cys amino acids that are prone to lose hydrogen atoms in the reaction. It can be seen that the ABTS free radical scavenging activity of lactoferrin polypeptides is related to the type of its amino acid residues, and different types of amino acid residues have different activities in free radical reactions.

[0072] Table 6. Scavenging ability of 0.5 mg / mL peptide on ABTS free radicals

[0073]

[0074]

[0075] Table 7. IC values of peptides containing Cys amino acid residues and carnosine for scavenging ABTS free radicals 50 value

[0076]

[0077]

Claims

1. An antioxidant peptide derived from lactoferrin, characterized in that, Its amino acid sequence is shown in SEQ ID NO:

24.

2. A nucleic acid encoding the antioxidant peptide according to claim 1.

3. An expression vector containing the nucleic acid according to claim 2.

4. A recombinant cell containing the expression vector according to claim 3.

5. Use of the antioxidant peptide according to claim 1 or its encoding nucleic acid in the preparation of products helpful for antioxidation.

6. The application according to claim 5, wherein The products refer to foods or cosmetics.

7. The application according to claim 6, characterized in that, The foods are health products.

8. The application according to claim 6 or 7, characterized in that, The antioxidant peptide is used as an active ingredient or an additive.

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