IY-series modified peptide with antioxidant activity and application of IY-series modified peptide

Abstract

The invention provides an IY-series modified peptide with antioxidant activity and application thereof, the disclosed IY-series modified peptide is a modified body of a parent peptide FR24, the antioxidant activity of the IY-series modified peptide is detected through an in-vitro free radical scavenging rate, and the IY-series modified peptide has higher antioxidant activity than the parent peptide FR24. Wherein IY-3 has the optimal in-vitro free radical scavenging activity. And the IY-3 is also very excellent in the aspects of cytotoxicity, hemolytic activity and the like. The IY-series modified peptide disclosed by the invention has antioxidant activity, can be used for preparing an antioxidant, an additive and the like and is applied to the industries of food, health care products, medicines and the like.

Description

Technical Field

[0001] The invention discloses an IY series modified peptide with antioxidant activity and application thereof. The IY series modified peptide is a modified form of a mother peptide FR24, has antioxidant activity, and relates to the field of biotechnology and biological products. Background Art

[0002] Antioxidant peptides have made outstanding contributions to improving human health by preventing and treating non-infectious chronic degenerative diseases such as diabetes, cardiovascular and cerebrovascular diseases, rheumatoid arthritis and cancer. In addition, peptides with antioxidant properties have effective metal ion chelating activity and lipid peroxidation inhibition ability, which makes them potential as food processing additives. Food spoilage, including oil rancidity and pigment discoloration, can cause unpleasant odors and potential toxic reactions, affect the nutritional value of food and shorten the shelf life. Therefore, finding effective antioxidants to reduce health and economic losses has become one of the current research hotspots.

[0003] As a bridge between physical principles and biological reactions, quantum chemistry plays an important role in drug discovery and activity prediction. In recent years, it has become an emerging trend to evaluate the relationship between the structure and activity of antioxidants through quantum chemical calculation methods. Quantum chemistry is based on the Schrödinger equation and predicts the activity of substances through certain approximations and assumptions. Among them, semi-empirical algorithms and density functional theory are the most commonly used methods for mining antioxidant peptides. Based on density functional theory, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) are the two most basic frontier molecular orbitals of a compound. The antioxidant activity of a substance can be reflected by calculating the energy gap between HOMO and LUMO. A large number of studies have reported the evaluation of the relationship between the structure and activity of antioxidants by quantum chemical methods, but there have been no reports on the modification of antioxidant peptides based on quantum chemical methods. Summary of the invention

[0004] The present invention provides an IY series modified peptide with strong antioxidant activity, which has antioxidant activity and can be used for preparing antioxidants and additives and applied in industries such as food, health products and medicines.

[0005] The present invention discloses an IY series modified peptide, wherein the first amino acid at the C-terminus of the IY series modified peptide is Ile, the last amino acid at the N-terminus is Tyr, and the central sequence of the IY series modified peptide is the same, which is: LGWWYYPHYYFY.

[0006] The IY series modified peptides described in the present invention include: IY-1; its amino acid sequence is SEQ ID No.1 in the sequence list; IY-2; its amino acid sequence is SEQ ID No. 2 in the sequence list; IY-3; its amino acid sequence is SEQ ID No.3 in the sequence list; IY-4, whose amino acid sequence is SEQ ID No.4 in the sequence listing.

[0007] The IY series modified peptides of the present invention are modified on the basis of polypeptide FR24; the IY series modified peptides retain high E HOMO amino acids with low E HOMO One or more amino acids of interest are deleted or substituted.

[0008] The amino acid sequence of FR24 is: FCDGISSVLGWCRYPHRRFRCTCR-NH 2 .

[0009] The sequence characteristics of an IY-1 modified peptide described in the present invention are: The length is 20 amino acids, the first four amino acids at the N-terminus of the FR24 sequence are deleted, and the Arg in the sequence is replaced by Tyr, Ser 6 and Ser 7 Replaced by Trp 2 and Pro 3 , Cys 12 Replaced by Trp 8 , Cys 21 Replace with Phe 17 , Thr 22 Replace with Phe 18 , Cys 23 Replaced by Pro 19 ; The specific amino acid sequence is: IWPVLGWWYYPHYYFYFFPY-NH 2 .

[0010] The sequence characteristics of an IY-2 modified peptide described in the present invention are: The length is 20 amino acids, and the Trp 2 Replaced by Pro 2 , Pro 3 Replaced by Trp 3 ,Phe 18 Replaced by Pro 18 ; The specific amino acid sequence is: IPWVLGWWYYPHYYFYFPPY-NH 2 .

[0011] The sequence characteristics of an IY-3 modified peptide described in the present invention are: The length is 20 amino acids, and the Trp 2 Replaced by Pro 2 , Pro 3 Replaced by Trp 3 ,Phe 17 Replaced by Pro 17 ; The specific amino acid sequence is: IPWVLGWWYYPHYYFYPFPY-NH 2 .

[0012] The sequence characteristics of an IY-4 modified peptide described in the present invention are: The length is 20 amino acids, and the Phe 17 Replaced by Pro 17 ,Phe 18 Replaced by Pro 18 , Pro 19 Replace with Phe 19 ; The specific amino acid sequence is: IWPVLGWWYYPHYYFYPPFY-NH 2 .

[0013] The present invention provides a series of modified peptides with antioxidant function, and the antioxidant activity of the antioxidant peptide FR24 and the IY series modified peptides are detected according to the national standard "Determination of Antioxidant Activity of Polypeptides—DPPH and ABTS Method" (GB / T 39100-2020). The IY series modified peptides have a good scavenging effect on DPPH free radicals and ABTS free radicals.

[0014] As a preferred embodiment, IY-3 in the IY series of modified peptides exhibits the strongest antioxidant activity and has a good scavenging effect on DPPH free radicals and ABTS free radicals.

[0015] The IY series antioxidant peptides provided by the present invention have low cytotoxicity, have lower cytotoxicity to mouse macrophages RAW264.7, and have lower hemolytic activity to mouse red blood cells.

[0016] The beneficial effects of the present invention are as follows: the parent peptide FR24 is modified by a quantum chemical calculation method to obtain an IY series of modified peptides. The activity is verified by the DPPH method and the ABTS method, and the antioxidant activity is good. The toxicity evaluation shows that the cytotoxicity and hemolytic activity are low. The antioxidant peptides obtained by the present invention can be applied to food preservation, cosmetics, health care products, etc., and are of great significance to the development of new antioxidant products. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a quantum chemical analysis diagram during the transformation process; A is FR24, B is IY-1, C is IY-2, D is IY-3, and E is IY-4; Figure 2 This is the antioxidant activity analysis of FR24 and IY series modified peptides; A is the DPPH free radical scavenging ability, and B is the ABTS free radical scavenging ability; Figure 3 It is a transmission electron microscopy image of IY-3 nanoliposomes; A is an empty nanoliposome, and B is an IY-3 nanoliposome encapsulated with chitosan; Figure 4 Fourier transform infrared spectra of nanoliposomes; Figure 5 It is the effect of nanoliposomes on the appearance of strawberries; Figure 6 This is the analysis of the preservation performance of strawberries coated with nanoliposomes. A is the weight loss assessment, B is the respiration intensity assessment, C is the total phenol content assessment, D is the ascorbic acid content assessment, E is the microbial contamination assessment, and F is the antioxidant activity assessment. DETAILED DESCRIPTION

[0018] Below, the present invention is described with reference to the following examples, but the present invention is not limited to the following examples. Unless otherwise specified, the technical means used in the examples are conventional means known to those skilled in the art, and the raw materials used are all commercially available products. All the raw and auxiliary materials selected in the present invention are well known in the art, and the % involved in the present invention are all mass volume percentages.

[0019] Example 1: Preparation of IY series modified peptides

[0020] The antioxidant peptide FR24 from Jilin Nonomura contains 24 amino acids. The electronic contribution of amino acids in the peptide FR24 was analyzed by quantum chemical calculation. Specifically, the PM7 semi-empirical method built into the Gaussian program was used to calculate the HOMO-LOMO orbit of the peptide and predict the position of the molecule with the strongest ability to contribute electrons. The molecular structure of the peptide was drawn using ChemDraw22.0.0, converted into a 3D structure using the built-in Chem3D, and the energy of the peptide conformation was minimized using the MM2 force field, with a minimum RMS gradient of 0.01. The results are shown in Figure 1As shown in the figure, the 20th amino acid Arg in FR24 occupies the highest electron orbital, representing the amino acid that is most likely to lose electrons. Since short peptides and peptides containing isoleucine (I), leucine (L) and alanine (A) at the N-terminus have stronger antioxidant activity, the residues with low electron energy contribution were deleted and the residues with high electron energy contribution were retained. At the same time, the amino acid I was exposed at the N-terminus, and the replacement of the amino acid residues with low electron contribution was attempted to obtain the IY series modified peptides IY-1, IY-2, IY-3 and IY-4; their amino acid sequences are SEQ ID No. 1~4 in the sequence table; the information of FR24 and IY series modified peptides is shown in Table 1 below.

[0021] Table 1

[0022] According to the above amino acid sequence, the whole sequence was synthesized by solid phase synthesis, desalted by HPLC reverse phase column chromatography, and the molecular weight was determined by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The purity of the purified polypeptide was identified by HPLC.

[0023] The results are: The molecular weight of the antioxidant peptide modified IY-1 is 2758.12 Da.

[0024] The molecular weight of the antioxidant peptide modified IY-2 is 2758.12 Da.

[0025] The molecular weight of the antioxidant peptide modified IY-3 is 2758.12 Da.

[0026] The molecular weight of the antioxidant peptide modified IY-4 is 2758.12 Da.

[0027] Example 2: Determination of the antioxidant activity of FR24 and IY series modified peptides

[0028] The antioxidant activity of the modified peptides was tested. The method for testing the ability to scavenge DPPH free radicals was based on the national standard GB / T39100-2020 Determination of Peptide Antioxidant Activity, Method I, DPPH Method; the method for testing the ability to scavenge ABTS free radicals was based on the national standard GB / T 39100-2020 Determination of Peptide Antioxidant Activity, Method II, ABTS Method. The results were expressed as the equivalent antioxidant capacity of vitamin E (Trolox) (μmol TE / μmol peptide).

[0029] The results are as follows Figure 2 As shown, the IY series of modified peptides all showed enhanced antioxidant activity compared to the parent peptide FR24. Among the IY series of modified peptides, IY-3 showed the most significant improvement in scavenging activity against DPPH and ABTS free radicals, with the scavenging activity against the two free radicals increased by about 2 times.

[0030] Example 3: Toxicity evaluation of FR24 and IY series modified peptides

[0031] 2 × 10 per well 5 Mouse macrophages RAW264.7 were inoculated at a density of 10 cells / well in a 96-well cell culture plate and placed in a CO 2 The cells were incubated in a constant temperature incubator at 37°C for 12 h with a concentration of 5%. Peptides of different concentrations were added according to the half-dilution method and placed in a CO 2 The cells were incubated in a constant temperature incubator at a concentration of 5% and a temperature of 37°C for 24 h. 10 μL of CCK-8 reagent was added to each well, mixed and cultured for 3 h in a dark environment. The absorbance at 450 nm of each well was detected by an ELISA instrument to calculate the cell half toxic concentration (CC50).

[0032] 2% (v / v) mouse red blood cell dilution was mixed with different concentrations of antioxidant peptides, incubated at 37°C for 1 hour, and centrifuged at 1000 g for 10 minutes. The supernatant was collected, the absorbance at 540 nm was detected, and the half hemolysis value (HC50) was calculated. 1% Triton X-100 was used as a positive control, and normal saline was used as a negative control. The specific results are shown in Table 2 below.

[0033] Table 2

[0034] As shown in Table 2, the IY series modified peptides provided by the present invention have weak cytotoxicity to mouse macrophage RAW264.7, and the cell half-toxic concentration is above 500 μM. The cell survival rate of FR24 is less than 50% at a concentration of 200 μM, so the IY series modified peptides have lower cytotoxicity than the parent peptide FR24. In addition, the half-hemolytic values ​​of the IY series modified peptides are also greater than those of the parent peptide FR24.

[0035] Example 4: Characterization of IY-3 Nanoliposomes

[0036] As a preferred peptide, IY-3 exhibited the strongest antioxidant activity among the IY series of modified peptides, so nanoliposomes loaded with IY-3 were prepared and characterized and evaluated for their application.

[0037] Specifically, 0.18 g of lecithin, 0.02 g of cholesterol, and 10 μL of Tween-80 were dissolved in 20 mL of anhydrous ethanol. After sufficient dissolution, the solution was transferred to a round-bottom flask, and the solvent was evaporated using a rotary evaporator. After storage in a desiccator for 16 h, 20 mL of peptide solutions of different concentrations were added to the film. The resulting mixture was vortexed for 2 min and stirred at 60 °C for 2 min, repeated 3 times. Ultrasonication was performed using an ultrasonic disruptor at a frequency of 20 kHz for 10 cycles (on for 1 min, pause for 1 min). Chitosan was then dissolved in 1% (v / v) acetic acid and stirred for 16 h. Finally, the same volume of each chitosan solution was added dropwise to the nanoliposome solution. After each sample was diluted 20 times with distilled water, the average particle size, aggregation index, and Zeta potential of the nanoliposomes were measured at room temperature and at an angle of 90 degrees using a dynamic light scattering system.

[0038] Further, 0.5 mL of liposome solution was mixed with 1 mL of acetone and centrifuged at 4°C and 5,000 g for 30 minutes. The supernatant containing unencapsulated polypeptide was separated and the solvent was evaporated at 60°C. Then it was dissolved with distilled water and the polypeptide content was determined by Bradford method. Finally, the encapsulation efficiency was obtained by calculating the percentage of polypeptide content loaded in the nanoliposome to the total polypeptide content. The results are shown in Table 3 below: Table 3 .

[0039] Note: Different letters in the same column represent significant differences (p < 0.05).

[0040] The average particle size of the empty liposomes (Blank-Lip) was 92.63 ± 2.18 nm. When loaded with different concentrations of IY-3 (0.05 mg / mL, 0.1 mg / mL, 0.2 mg / mL, and 0.4 mg / mL), the particle size of the liposomes gradually increased. The PDI of different nanoliposome samples ranged from 0.18 to 0.47, indicating that the particle size distribution of the nanoliposomes was relatively uniform. With the increase of IY-3 concentration, the encapsulation efficiency of the liposomes gradually increased. When the concentration of IY-3 reached 0.2 mg / mL, the encapsulation efficiency of the liposomes was the highest. Therefore, liposomes containing 0.2 mg / mL of IY-3 were selected for chitosan coating. The Zeta potential of Blank-Lip was -51.37 ± 0.95 mV, while the liposomes containing polypeptides showed a gradually increasing charge due to the polypeptides surrounding and encapsulating in the liposomes.

[0041] Furthermore, the nanoliposome samples were stained with 1% phosphotungstic acid (pH = 6.5-7.0) for 10 s, placed on a copper grid, dried naturally, and observed by transmission electron microscopy at an accelerating voltage of 100 kV. Figure 4 .

[0042] By the attached Figure 4 The results show that the structure of the IY-3 nanoliposome (IY-3-Lip) provided by the present invention is close to spherical, has a vesicle structure, and has no obvious aggregation and fusion phenomenon. After coating with chitosan, the outer membrane thickness of the liposome increases and the number of layers increases, which further proves that chitosan is adsorbed on the outer surface of the liposome, increasing the thickness and particle size of the liposome.

[0043] Furthermore, 0.2 g of dried potassium bromide and 0.002 g of the sample were mixed and ground, and pressed into transparent, uniform, crack-free tablets. The FTIR spectra of the samples were recorded using a Fourier transform infrared spectrometer (FTIR). The broad spectrum range was 400–4000 cm -1 , the measurement resolution is 0.1 cm -1 For detailed results, please see the attached Figure 5 .

[0044] By the attached Figure 5 The results show that after nanoliposomes were loaded with IY-3, CH 2 The stretching vibration peak at 2852 cm -1 Move to 2850 cm -1 966 cm -1 The peak at 969 cm -1 , indicating that IY-3 exists in the lipid polar region, that is, inside the vesicle. 1734 cm -1 The peak at 1737 cm reflects the carbonyl (C=O) stretching vibration of the aliphatic ester bond connecting the hydrocarbon chain to the head group. -1 The peaks at 2850 cm-1 were shifted to higher wavenumbers, confirming that the C=O group of phospholipids and IY-3 interacted by forming hydrogen bonds. After chitosan coating, part of the peaks in the liposomes were replaced by chitosan. -1 CH 2 The stretching vibration did not move significantly after chitosan coating, indicating that chitosan modification on the liposome surface had no effect on the main structure of the liposome. The results of infrared spectroscopy analysis showed that IY-3 was located in the polar region of the liposome, and chitosan could be well coated on the liposome surface.

[0045] Example 5: Effect of IY-3 nanoliposome coating on strawberry preservation

[0046] Strawberries with uniform size, no defects and a surface redness of 90% were selected to evaluate the effect of nanoliposome coating on strawberry quality and freshness. Each group of strawberries (n = 5) was immersed in the coating solution for 1 minute using a coating with or without antioxidant peptides and then air-dried in a fume hood. Strawberries without any treatment served as a control. All strawberries were stored at 19-25°C and 40-50% humidity. The strawberries were photographed and weighed every 24 hours to calculate the weight loss. For specific results, see the attached Figure 6 .

[0047] By the attached Figure 6 The results showed that the quality of strawberries in the control group decreased significantly during storage at room temperature. After 7 days of storage, there were signs of decay, severe shrinkage, and large areas of mold growth were observed. In the IY-3-Lip group, only one strawberry was partially moldy, and the rest of the strawberries remained relatively fresh. In contrast, the fruits in the chitosan-coated IY-3 nanoliposome coating (CS-IY-3-Lip) group showed almost no signs of mold growth, and the appearance was intact, with only a certain degree of color deepening. The strawberries in the control group were severely wrinkled after 7 days of storage, with a weight loss of 52.51 ± 4.7%. Under the same storage conditions, the strawberries in the CS-IY-3-Lip group had the least weight loss, which was 14.97 ± 2.27%.

[0048] Furthermore, strawberries (1 kg) from different treatment groups were placed under ambient conditions for 1 h to allow the accumulation of CO in the tissues to 2 The strawberries were then placed in a sealed container containing 10 mL of 0.4 mol / L NaOH solution. After 30 minutes, 2 drops of phenolphthalein were added and the mixture was titrated with 0.2 mol / L oxalic acid. The respiration intensity of the strawberries was expressed as CO 2 The specific results are shown in the attached Figure 6 .

[0049] By the attached Figure 6 The results show that the initial respiration intensity of strawberry is about 56.94 mg CO 2 / kg·h. After 3 days of storage, the respiration rate of strawberries coated with IY-3-Lip and CS-IY-3-Lip was reduced to about half of the original. The respiration intensity of strawberries in the control group was higher than that of strawberries coated with the coating during storage. After 7 days of storage, the respiration rate of strawberries coated with IY-3-Lip and CS-IY-3-Lip was significantly lower than that of strawberries in the control group.

[0050] Furthermore, the total phenolic content of strawberries was determined by the Folin-Ciocalteu method. On days 0, 3, and 7, 0.1 g of strawberries were ground with liquid nitrogen, added with 1.5 mL of pre-cooled 95% (v / v) methanol, and homogenized for 5 minutes. After incubation for 2 hours, the mixture was centrifuged at 10,000 g for 20 minutes, 100 μL of the supernatant was incubated with 200 μL of 10% (v / v) Folin-Ciocalteu phenol reagent for 5 minutes, and 800 μL of 0.7 mol / L Na 2 CO 3 The reaction was terminated and incubated for 2 hours in the dark. The absorbance of each sample was measured at 765 nm using an ELISA reader. Gallic acid was used as the standard and the total phenol content was expressed as milligrams of gallic acid equivalent in strawberry (mg GAE / 100 g). Figure 6 .

[0051] By the attached Figure 6 The results showed that the total phenolic content of fresh strawberries was 211.48 mg gallic acid equivalent (GAE) / 100 g strawberries. After 3 days of storage at room temperature, the total phenolic content of strawberries in the control group decreased to 151.24 mg GAE / 100 g, and the total phenolic content of strawberries in the two coatings was significantly higher than that in the control group. After 7 days of storage, the phenolic content of strawberries coated with IY-3-Lip and CS-IY-3-Lip was 189.75 mg GAE / 100 g and 200.12 mg GAE / 100 g, respectively, which was significantly higher than that of strawberries in the untreated group (30.63 mgGAE / 100 g), indicating that IY-3-Lip and CS-IY-3-Lip coatings had a good effect on the preservation of phenolic compounds.

[0052] Furthermore, 100 g of strawberries and 100 mL of 2% oxalic acid solution were mashed and filtered. 20 mL of liquid was taken and diluted to 100 mL with 2% oxalic acid solution, 5 g of white clay was added for decolorization, and 10 mL of filtrate was taken after filtration and titrated with a standardized 2,6-dichloroindophenol solution until the solution turned pink and did not fade within 15 seconds. At the same time, 10 mL of 2% oxalic acid solution was taken as a blank control. The results were expressed as milligrams of ascorbic acid per 100 mL sample.

[0053] By the attached Figure 6The results showed that the trend of ascorbic acid (Vc) content in different treatment groups during storage was similar to that of total phenol content. The Vc content of fresh strawberries was 61.87 mg / 100 g strawberries. After 7 days of storage, the Vc content of uncoated strawberries decreased significantly to 8.53 mg / 100 g strawberries, but the Vc content of the coated strawberries was significantly higher than that of the control group, indicating that IY-3-Lip and CS-IY-3-Lip coatings can effectively reduce the loss of Vc in strawberries.

[0054] Furthermore, 5 g of strawberry sample was crushed and placed in 25 mL of PBS solution containing 0.2% Tween-80. After grinding, a series of 10-fold dilutions were prepared in PBS. 1 mL of each sample was mixed with about 15 mL of rose bengal sodium agar. The solidified plates were incubated at 37°C for 48 hours and the number of colonies was counted. The specific results are shown in the attached Figure 6 .

[0055] By the attached Figure 6 The results showed that the coating treatment groups inhibited the proliferation of yeast and mold to varying degrees, especially the CS-IY-3-Lip coating treatment group. After 7 days of storage, the number of yeast and mold in the CS-IY-3-Lip coating treatment group was reduced by more than 3 orders of magnitude compared with the control group (CS-IY-3-Lip coating treatment group: 3.68 lg CFU / g, control group: 6.72lg CFU / g). The results showed that the CS-IY-3-Lip coating has the ability to resist the growth or contamination of yeast and mold.

[0056] Further, 1 mL of 0.01% DPPH was mixed with 1 mL of fruit extract. The mixed solution was stored in the dark at room temperature for 30 minutes, and then the antioxidant activity of strawberry was determined by DPPH assay. The specific results are shown in the attached Figure 6 .

[0057] The fruit extract mixture was prepared by mashing 25 g of fruit pulp and distilled water.

[0058] By the attached Figure 6 The results showed that the antioxidant activity of strawberries in the control group gradually decreased during the entire storage process, and the DPPH clearance rate reached 59.73% on the 7th day. The use of IY-3-Lip and CS-IY-3-Lip coatings inhibited the decline in antioxidant activity, among which the DPPH clearance rate of the CS-IY-3-Lip coating treatment group was close to the initial DPPH clearance rate, indicating that the CS-IY-3-Lip coating has the effect of inhibiting strawberry oxidation.

[0059] In summary, the above embodiments are merely descriptions of the preferred implementation methods of this test, and do not limit the scope of this test. Without departing from the spirit of the design of this test, various modifications and improvements made to the technical solutions of this test by ordinary technicians in this field should fall within the protection scope determined by this test.

Claims

1. An IY series modified peptide, characterized in that: The first amino acid at the C-terminus of the IY series modified peptides is Ile, the last amino acid at the N-terminus is Tyr, and the central sequence of the IY series modified peptides is the same, which is: LGWWYYPHYYFY.

2. An IY series modified peptide according to claim 1, characterized in that The IY series modified peptides include: IY-1; its amino acid sequence is SEQ ID No.1 in the sequence list. IY-2; its amino acid sequence is SEQ ID No.2 in the sequence list. IY-3; its amino acid sequence is SEQ ID No.3 in the sequence list. IY-4, whose amino acid sequence is SEQ ID No. 4 in the sequence list.

3. The IY series modified peptide according to claim 1, characterized in that: It has enhanced antioxidant activity and low cytotoxicity compared to the parent peptide FR24.

4. Use of the IY series modified peptides according to claims 1-2 in the preparation of free radical scavenging products.

5. The use according to claim 4, characterized in that The free radicals are DPPH free radicals and / or ABTS free radicals.

6. Use of the IY series modified peptides as claimed in claims 1 to 4 in the preparation of antioxidant products.

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