Neuroprotective polypeptide and application thereof

Abstract

The invention discloses a neuroprotective peptide with anti-inflammatory and anti-oxidation effects and application of the neuroprotective peptide. The neuroprotective polypeptide is a polypeptide with any one of the following sequences: FPDFVYK and APDTRLF. The invention provides an antioxidant effect of the neuroprotective polypeptide in a PC12 cell injury model induced by hydrogen peroxide, and the neuroprotective polypeptide can be used for preparing antioxidant drugs. The invention provides an anti-inflammatory effect of the neuroprotective polypeptide in a PC12 cell injury model induced by hydrogen peroxide, and the neuroprotective polypeptide can be used for preparing anti-inflammatory drugs. The invention provides the influence of the neuroprotective polypeptide on the expression of pathways and neurotrophic factors in PC12 nerve cells. The neuroprotective polypeptide reduces the activity of acetylcholin esterase (AChE) and up-regulates the expression of neurotrophic factors so as to alleviate nerve cell damage and enhance memory, thereby achieving the purpose of preventing and treating neurodegenerative diseases.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of active peptides, and particularly relates to a neuroprotective peptide and application thereof. BACKGROUND

[0002] In the modern society with rapid development, the productivity is developing rapidly, while the mental stress, sleep disorders and nerve damage problems are also intensified. About 35% of the adult population in the world has different degrees of memory loss symptoms. It is worth noting that the acceleration of population aging leads to a continuous rise in the incidence of neurodegenerative diseases. According to the statistics in the China Alzheimer's Disease Report 2021, the size of Alzheimer's disease patients in China accounts for 20% of the total number of patients in the world, ranking first in the world. Therefore, the development of prevention strategies and intervention mechanisms for neuroprotective related diseases has become a hot spot, especially the screening of neuroprotective agents based on natural products (such as food-derived active peptides, plant polyphenols, etc.). Studies have shown that oxidative stress and inflammatory damage in the central nervous system are important factors leading to neurodegenerative diseases. Food-derived active peptides have become a hot direction for the development of neuroprotective agents due to their multi-target regulation potential (such as antioxidant, anti-inflammatory, neurotrophic), low toxicity and blood-brain barrier penetration ability.

[0003] Pig brain, as an important by-product of livestock processing industry, is rich in protein and a high proportion of hydrophobic amino acids (such as proline, phenylalanine, etc.), and its amino acid composition is highly adapted to the function regulation of central nervous system, which is an ideal raw material for developing neuroprotective active peptides. China, as the world's largest pig producer, is rich in pig brain resources, but most of them are not effectively utilized, only part of them are used for traditional food processing, and the rest are converted into low-value feed or directly discarded due to lagging processing technology, which not only causes resource waste, but also causes environmental pollution problems due to the high lipid content of brain tissue. Pig brain is rich in protein, fatty acids, peptides and trace elements, and there have been related reports on its neuroprotective effect, but the key functional factors have not been systematically studied, especially there are few reports on active peptides.

[0004] Based on the above problems, the present application takes low molecular weight active peptides (MW < 3 kDa) in pig brain enzymatic hydrolysate as the research object, obtains pig brain neuroprotective peptides based on virtual screening technology, verifies the neuroprotective activity of the pig brain neuroprotective peptides by using PC12 cell damage model, and explores the mechanism of the pig brain characteristic neuroprotective peptides in antioxidant, anti-inflammatory and neurotrophic factor expression by using real-time fluorescent quantitative PCR technology, so as to provide a new idea for the efficient utilization of pig brain resources and the prevention and treatment of cognitive impairment, and is expected to be used in the treatment of related diseases (such as neurodegenerative diseases such as Alzheimer's disease). SUMMARY

[0005] The present application aims to provide a neuroprotective peptide with anti-inflammatory and antioxidant effects and application thereof.

[0006] To achieve the above object, the present application adopts the following technical solutions: The present application provides a neuroprotective polypeptide, which is a polypeptide of any one of the following sequences: FPDFVYK, APDTRLF, both of which are Synthetic construct.

[0007] The present application provides the antioxidant effect of the above-mentioned neuroprotective polypeptide in a hydrogen peroxide-induced PC12 cell damage model, which can be used for preparing an antioxidant drug.

[0008] The present application provides the anti-inflammatory effect of the above-mentioned neuroprotective polypeptide in a hydrogen peroxide-induced PC12 cell damage model, which can be used for preparing an anti-inflammatory drug.

[0009] The present application provides the influence of the above-mentioned neuroprotective polypeptide on pathways and neurotrophic factor expression in PC12 nerve cells.

[0010] A polypeptide drug, which comprises a neuroprotective polypeptide and a pharmaceutically acceptable excipient.

[0011] Compared with the prior art, the present application has the following beneficial effects: The polypeptide provided by the present application has good anti-inflammatory and antioxidant effects, low toxicity, and can improve cell survival rate, improve cell membrane damage, and reduce cell apoptosis after being administered to cells. In addition, after being administered to cells, the polypeptide up-regulates Nrf2 and HO-1 expression, activates the Nrf2 / HO-1 pathway, reduces cell damage caused by oxidative stress, and reduces nerve inflammation. At the same time, the polypeptide can enhance the activity of the CREB signaling pathway and promote nerve protection and cell repair by up-regulating BDNF expression, thereby providing support for pig brain peptide to relieve nerve damage. The above experimental results show that the polypeptide has the activity of inhibiting nerve inflammation and nerve oxidative stress, and has good application prospects in the preparation of nerve protection drugs.

[0012] In addition, the amino acid sequence of the new polypeptide is disclosed, and the new polypeptide can be further developed for research in the field of treatment of neurodegenerative diseases. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 Toxic effects of different concentrations of H2O2 on PC12 cells Figure 2 Effects of polypeptides FPDFVYK and APDTRLF on MDA levels of PC12 cells induced by H2O2 (different letters on the column represent significant differences p < 0.05); Figure 3 Effects of polypeptides FPDFVYK and APDTRLF on ROS levels of PC12 cells induced by H2O2 (different letters on the column represent significant differences p < 0.05); Figure 4 Effects of polypeptides FPDFVYK and APDTRLF on SOD levels of PC12 cells induced by H2O2 (different letters on the column represent significant differences p < 0.05); Figure 5 Effects of polypeptides FPDFVYK and APDTRLF on CAT activity of PC12 cells induced by H2O2 (different letters on the column represent significant differences p < 0.05); Figure 6 Effects of polypeptides FPDFVYK and APDTRLF on AChE activity of PC12 cells induced by H2O2 (different letters on the column represent significant differences p < 0.05); Figure 7 Effects of polypeptides FPDFVYK and APDTRLF on TNF-α levels of PC12 cells induced by H2O2 (different letters on the column represent significant differences p < 0.05); Figure 8 Effects of polypeptides FPDFVYK and APDTRLF on IL-6 levels of PC12 cells induced by H2O2 (different letters on the column represent significant differences p < 0.05); Figure 9 Effects of polypeptides FPDFVYK and APDTRLF on IL-1β levels of PC12 cells induced by H2O2 (different letters on the column represent significant differences p < 0.05); Figure 10 Effects of polypeptides FPDFVYK and APDTRLF on NO levels of PC12 cells induced by H2O2 (different letters on the column represent significant differences p < 0.05); Figure 11Effects of polypeptides FPDFVYK and APDTRLF on mRNA expression levels of Nrf2 and HO-1 in PC12 cells induced by H2O2 (different letters on the columns represent significant differences p < 0.05). Figure 12 Effects of polypeptides FPDFVYK and APDTRLF on mRNA expression levels of CREB and BDNF in PC12 cells induced by H2O2 (different letters on the columns represent significant differences p < 0.05). DETAILED DESCRIPTION

[0014] The specific embodiments of the present application are further described below. It is to be understood that the description of these embodiments is intended to help understand the present application, but does not constitute a limitation of the present application. In the following examples, the experimental methods are conventional methods, and the experimental materials used in the following examples are commercially available unless otherwise specified.

[0015] The polypeptides FPDFVYK and APDTRLF of the present application are synthesized by a solid-phase synthesis method known in the art, and the purity is greater than 95%.

[0016] Example 1: Study on the antioxidant effect of polypeptides 1.1. Cell culture The PC12 cell cryopreservation tube placed in the -80 ℃ ultra-low temperature refrigerator was quickly transferred to the constant temperature water bath pot at 37 ℃, and was continuously shaken to quickly melt. In the clean bench, the melted liquid was transferred to a 15 mL centrifuge tube and centrifuged for 5 min at 1,000 rpm, and then the supernatant was discarded, 1 mL of complete culture medium (RPMI 1640 culture medium containing 1% of a double-antibody solution and 10% FBS) was added to resuspend the cells and transferred to a new culture bottle, and the complete culture medium was supplemented to 5 mL / bottle, and placed in a 37 ℃, 5% CO2 incubator for culture. After 12 h, the cell adhesion and growth were observed under a microscope, the complete culture medium was replaced, and the culture was continued. The logarithmic growth phase cells were used for experiments.

[0017] 1.2. Construction of PC12 cell oxidative damage model The PC12 cells were seeded in 96-well plates at 2×10 5Cells were seeded at a density of 100 μL / mL in 96-well plates and incubated at 37 °C with 5% CO2 for 24 h. Cells were then divided into control, blank, and H2O2 groups (final H2O2 concentrations of 0, 100, 200, 300, 400, 500, 600, 700, and 800 μmol / L, respectively) for 1 h incubation, with 6 replicates per group. The control group received no H2O2, and the blank group received neither cells nor H2O2. After culture, cell proliferation was measured using the CCK-8 assay to determine the optimal H2O2 concentration and duration of damage.

[0018] The results are as follows Figure 1 As shown, 400 μM H2O2 was selected as the optimal half-lethal concentration, and PC12 cell model of oxidative damage was established by incubation for 2 h.

[0019] 1.3. Cell Sample Preparation After digestion, centrifugation, and resuspending, the cells were seeded into 6-well plates at a ratio of 2 × 10⁶ cells per well. 5 To determine the optimal cell concentration, 2 mL of cell suspension was added to each well. After incubation at 37 °C and 5% CO2 for 24 h until all cells adhered, the culture medium in the 6-well plate was aspirated, and 2 mL of RPMI 1640 medium was added to each of the control and model wells. For the sample groups, 2 mL of a 200 μg / mL peptide solution diluted with RPMI 1640 medium was added, and for the positive group, 2 mL of vitamin E at a final concentration of 100 μM was added. The plates were then incubated at 37 °C and 5% CO2 for another 24 h. After incubation, all groups except the control group were treated with 400 μM H2O2 and incubated at 37 °C and 5% CO2 for another 2 h. The 6-well plates were then removed from the incubator, the culture medium was discarded, and the cells were washed three times with PBS. High-performance RIPA cell lysis buffer was added, and the cells were lysed on ice for 30 min. Subsequently, refrigerated centrifugation was performed at a speed of 10,000 r / min for 4 min, and the supernatant was collected for analysis.

[0020] 1.4. Effect of the present invention's peptides on antioxidant activity in a cell damage model Oxidative stress can induce neuronal damage through lipid peroxidation, enzyme inactivation, and DNA modification, ultimately leading to impaired memory and cognitive function. Recent research reports that oxygen free radicals are considered a major cause of neuronal damage and death during cognitive decline. Following the experimental methods in 1.3, cell supernatant was collected, and the OD values ​​of intracellular MDA, ROS, SOD, and CAT were measured colorimetrically according to the instructions of the MDA, SOD, CAT, and ROS kits, and their activities were calculated.

[0021] MDA is a metabolite of lipid peroxidation and a key biomarker for assessing the degree of oxidative damage to neurons. It can indirectly reflect the degree of cell damage and also the extent of oxidative stress-induced damage to cells. Figure 2 As shown, the MDA level in the model group was higher than that in the control group ( p < 0.05 indicates successful model establishment. Intracellular MDA levels decreased after pretreatment with FPDFVYK and APDTRLF, to 1.66 ± 0.07 nmol / mgprot and 1.52 ± 0.13 nmol / mgprot, respectively, representing reductions of 9.72% and 17.27%. The difference in MDA levels between the experimental group and the model group pretreated with FPDFVYK was small, while the difference between the experimental group and the model group pretreated with APDTRLF was significant. These results indicate that FPDFVYK and APDTRLF can protect the cell membrane to some extent by inhibiting lipid peroxidation.

[0022] Reactive oxygen species (ROS) are natural byproducts of neuronal oxidative metabolism. They play a crucial regulatory role in the development and homeostasis of the nervous system by modulating processes such as synaptic plasticity, neurotransmitter release, and mitochondrial biosynthesis. In Alzheimer's and Parkinson's diseases, abnormally elevated ROS levels exacerbate neurological damage. Therefore, restoring the dynamic balance of ROS in the brain has become an important intervention strategy for slowing the neurodegenerative process. Changes in intracellular ROS levels can reflect oxidative stress generated in PC12 cells after oxidative damage. Figure 3 As shown, compared with the control group, when treated with H2O2 alone, the ROS level in PC12 cells of the model group increased significantly by approximately 1.61-fold ( ). p The value < 0.05 indicates successful model establishment. However, compared with the model group, pretreatment with FPDFVYK and APDTRLF significantly reduced ROS production. ROS levels in PC12 cells increased by approximately 1.24-fold and 1.12-fold, respectively, after pretreatment with FPDFVYK and APDTRLF, with APDTRLF showing significantly better results than FPDFVYK. These results indicate that FPDFVYK and APDTRLF can effectively reduce ROS levels in damaged PC12 cells, thereby alleviating H2O2-induced oxidative damage.

[0023] Superoxide dismutase (SOD) is an essential free radical scavenger in the human body, protecting brain tissue from free radical damage. SOD levels reflect the load of the intracellular antioxidant enzyme system, indirectly indicating the level of intracellular free radicals and reflecting oxidative damage to cells. SOD protects nerve cell membrane phospholipids, mitochondrial electron transport chains, and synaptic vesicle proteins from oxidative damage by scavenging excess superoxide anions and catalyzing their decomposition into H₂O₂. It also participates in regulating the secretion of neurotrophic factors (such as BDNF) and synaptic remodeling. However, when SOD activity is significantly reduced, the efficiency of superoxide anion scavenging decreases, leading to a surge in oxidative stress, a significant contributing factor to neurodegenerative diseases. Therefore, targeting and enhancing SOD activity or synergistically regulating its downstream CAT activity is a key strategy for intervening in neurodegenerative diseases. When PC12 cells are damaged by H₂O₂, due to cytoplasmic lipid peroxidation, the level of free radicals increases, and the consumption of the free radical scavenger SOD increases accordingly. Figure 4 As shown, compared with the control group, the SOD level in the H2O2-treated model group was significantly reduced ( p < 0.05 indicates increased intracellular SOD consumption. Compared with the model group, intracellular SOD levels were significantly increased after treatment with FPDFVYK and APDTRLF ( p The levels of APDTRLF were 25.52 ± 0.12 U / mgprot and 27.23 ± 0.61 U / mgprot, respectively, and the levels of APDTRLF were significantly higher than those of FPDFVY. This indicates that FPDFVYK and APDTRLF can restore SOD activity and protect cells from oxidative damage.

[0024] Catalytic oxygenase (CAT) is a key enzyme in the antioxidant defense system, precisely regulating the metabolic balance of reactive oxygen species within neurons by catalyzing the decomposition of hydrogen peroxide into water and oxygen. However, when CAT activity significantly decreases, the abnormal accumulation of H2O2 disrupts redox homeostasis, becoming a core driving factor in neurodegenerative damage. Figure 5 As shown, compared with the control group, the CAT activity of PC12 cells in the model group decreased significantly by 57.03% ( p < 0.05), its antioxidant function was impaired. Compared with the model group, the intracellular CAT activity increased by 6.24% and 12.26% after treatment with FPDFVYK and APDTRLF (P<0.05), respectively, indicating that FPDFVYK and APDTRLF can inhibit oxidative stress to a certain extent. Among them, the APDTRLF group showed higher CAT enzyme activity, which was superior to the FPDFVYK group (P<0.05). p (< 0.05), indicating that APDTRLF may have superior antioxidant activity compared to FPDFVYK.

[0025] In summary, the experiments in section 1.4 demonstrate that the aforementioned peptides possess excellent antioxidant effects.

[0026] 1.5. Effect of the present invention's peptides on acetylcholinesterase activity in a cell injury model AChE is a core regulatory enzyme in the cholinergic neurotransmission system, precisely terminating neural signal transmission in the synaptic cleft by catalyzing the hydrolysis of ACh into choline and acetic acid. ACh is the main excitatory neurotransmitter in neurons and plays a crucial role in cognitive function. Significantly reduced ACh levels can lead to cognitive and memory impairments associated with Alzheimer's disease. Furthermore, uncontrolled oxidative stress during neurodegenerative diseases can also cause imbalances in the cholinergic system, and even lipid peroxidation can enhance acetylcholinesterase activity. Following the experimental methods in 1.3, cell supernatant was collected, and the relevant concentrations and activities were determined using the BCA protein quantification kit and the AChE kit.

[0027] The results are as follows Figure 6 As shown, compared with the control group (3.67 ± 0.41 nmol / min / mg prot), the AChE activity in the model group cells was significantly increased ( p < 0.05). Compared with the model group, the AChE activity of cells treated with FPDFVYK and APDTRLF decreased to 5.21 ± 0.79 and 4.68 ± 0.41 nmol / min / mg prot, respectively. This suggests that FPDFVYK and APDTRLF may exert a protective effect against nerve damage and alleviate H2O2-induced neuronal damage by reducing AChE activity in H2O2-induced PC12 cells and increasing intracellular neurotransmitter levels.

[0028] In summary, the experiments in section 1.5 show that the above-mentioned peptides can exert neuroprotective effects by regulating acetylcholinesterase activity.

[0029] Example 2: Study on the anti-inflammatory effect of peptides 2.1. Effects of the present invention's peptides on anti-inflammation in a cell injury model Excessive accumulation of ROS leads to the release of inflammatory factors, resulting in inflammatory responses and further toxicity to nerve cells. Following the experimental methods in 1.3, the levels of TNF-α, IL-1β, IL-6, and NO in the cell supernatant were measured according to the instructions of the enzyme-linked immunosorbent assay (ELISA) kit.

[0030] TNF-α is an important pleiotropic cytokine in the central nervous system, involved in neural development and homeostasis. For example... Figure 7 As shown, compared with the control group, the TNF-α level in the model group was significantly increased to 78.78 ± 1.99 pg / mL (p < 0.05, which was 2.38 times that of the control group. After treatment with FPDFVYK and APDTRLF, the TNF-α level in cells was significantly lower than that in the model group ( p The concentrations of TNF-α decreased to 66.76 ± 2.52 pg / mL after treatment with FPDFVYK and 59.35 ± 2.25 pg / mL after treatment with APDTRLF, representing decreases of 15.26% and 24.66%, respectively. These results indicate that FPDFVYK and APDTRLF can improve H2O2-induced PC12 cell damage by downregulating cellular TNF-α concentration, thereby achieving anti-inflammatory effects.

[0031] IL-6 is a cytokine in the central nervous system with dual functions of neuroregulation and immunoregulation, playing a complex role in the dynamic balance between cellular oxidative stress and neuroprotection. The effects of FPDFVYK and APDTRLF on IL-6 secretion in PC12 cells are as follows: Figure 8 As shown in the figure. Compared with the control group, the IL-6 level in the supernatant of PC12 cells stimulated by H2O2 was significantly increased to 109.59 ± 3.83 pg / mL ( p < 0.05%, which was 1.72 times that of the control group. Compared with the model group, FPDFVYK and APDTRLF significantly reduced the level of IL-6 in the supernatant of PC12 cells ( p < 0.05), where the concentration of IL-6 decreased to 93.35 ± 4.50 pg / mL after treatment with FPDFVYK and to 93.08 ± 33.97 pg / mL after treatment with APDTRLF, representing decreases of 14.82% and 15.07%, respectively. The effects of FPDFVYK and APDTRLF on IL-6 levels are similar to those of TNF-α, which can reduce neuronal damage by lowering the levels of inflammatory factors.

[0032] IL-1β is a key inflammatory regulator in the central nervous system, playing a crucial role in maintaining redox homeostasis in the brain. When IL-1β is dysregulated, its pathological concentration promotes oxidative stress and inflammatory responses, exacerbating neurological damage. Figure 9 As shown, compared with the control group, the IL-1β level in the model group cells was significantly increased to 109.98 ± 2.07 pg / mL (…). p <0.05%, which was 1.50 times that of the control group. Compared with the model group, the IL-1β levels in the FPDFVYK and APDTRLF groups were reduced ( p<0.05), where the concentration of IL-1β decreased to 98.27 ± 1.55 pg / mL after treatment with FPDFVYK and to 97.24 ± 4.69 pg / mL after treatment with APDTRLF, representing decreases of 10.64% and 11.59%, respectively, indicating that FPDFVYK and APDTRLF have a mitigating effect on inflammation induced by H2O2-induced PC12 cell damage model.

[0033] NO, as an important inflammatory factor, participates in various physiological and pathological processes within the central nervous system, and its level changes can directly reflect the inflammatory state of nerve cells. When PC12 cells are induced by hydrogen peroxide, the intracellular oxidative stress level increases significantly, activating a series of inflammation-related signaling pathways and increasing NO production. While NO, as a signaling molecule, can participate in regulating various cellular physiological functions, its excessive production under inflammatory conditions can cause cellular damage. Figure 10 As shown, compared with the control group, 400 μM H2O2 significantly increased the NO content in PC12 cell culture medium by 2.41 times ( p <0.05). Compared with the model group, both FPDFVYK and APDTRLF significantly reduced NO release, decreasing it by 27.42% and 37.50%, respectively. p The results (< 0.05) indicate that FPDFVYK and APDTRLF can inhibit the increase in NO levels caused by H2O2, thereby reducing inflammation of nerve cells and exerting a neuroprotective effect.

[0034] In summary, the experiments in section 2.1 demonstrate that the aforementioned peptides possess excellent anti-inflammatory effects.

[0035] Example 3: Study on the neuroprotective mechanism of peptides 3.1. RNA Extraction RNA was extracted using a rapid RNA extraction kit for cells, and the RNA concentration was measured using an ultra-micro nucleic acid analyzer after extraction.

[0036] 3.2. Reverse transcription of cDNA First, add each reaction component to the RNase-free PCR tube in the order specified in the instructions, and then centrifuge to mix thoroughly. Place the prepared PCR tube into the PCR instrument and set the reverse transcription reaction program according to the instructions. After reverse transcription is completed, the obtained RNA transcription product can be used immediately for the next step of real-time quantitative PCR (RT-qPCR) experiment, or stored at -80 ℃.

[0037] 3.3. Real-time PCR reaction Prepare the qPCR reaction system on ice according to the instructions, then quickly transfer it to a qPCR instrument preheated to 95 °C and follow the preset program in the instructions. The primer sequences added to the reaction system are shown in Table 1, with the β-actin gene used as an internal control.

[0038] Table 1 Primer sequences of related genes Nrf2 is a key transcription factor for activating cell-protective genes and an important target for the prevention and treatment of neurodegenerative diseases. It enhances the cell's ability to cope with oxidative stress by upregulating the expression of various antioxidant enzymes. HO-1 is one of the downstream target genes of Nrf2 and has significant antioxidant and anti-inflammatory effects. Figure 11 As shown, FPDFVYK and APDTRLF significantly increased the mRNA expression of Nrf2 and HO-1, respectively, thereby regulating cellular antioxidant stress responses and reducing free radical damage induced by hydrogen peroxide. Compared with the model group, the expression of Nrf2 and HO-1 in the FPDFVYK and APDTRLF groups was significantly increased. Figure 11 As can be seen from this, the mRNA expression of Nrf2 in the FPDFVYK and APDTRLF groups was significantly increased by 25.71% and 33.58%, respectively; Figure 11 b shows that the mRNA expression of HO-1 in the FPDFVYK and APDTRLF groups was significantly increased by 28.92% and 31.75%, respectively. The results indicate that the FPDFVYK and APDTRLF peptides can effectively alleviate the damage of oxidative stress to PC12 cells by activating the Nrf2 / HO-1 pathway.

[0039] Brain-derived neurotrophic factor (BDNF) is a downstream target of CREB and is widely expressed in the nervous system and its receptors. Redox imbalance and excessive pro-inflammatory cytokines may lead to persistent neuronal damage by inhibiting BDNF. Alterations in BDNF expression levels and disruption of the CREB / BDNF signaling pathway may result in synaptic loss and cognitive impairment. The expression levels of CREB mRNA and BDNF mRNA in hydrogen peroxide-induced PC12 cells were determined by RT-qPCR. Figure 12 As shown in figure a, compared with the control group, the CREB mRNA level was significantly downregulated by 28.83% by 400 μM hydrogen peroxide. p < 0.05). However, compared with the model group, porcine brain peptides FPDFVYK and APDTRLF increased the mRNA expression level of the CREB gene by 0.70 and 0.82 times, respectively, compared with the model group. p < 0.05), and further promotes the transcription of downstream genes of CREB. For example... Figure 12As shown in b, compared with the control group, the BDNF mRNA level was significantly downregulated by 44.42% by 400 μM hydrogen peroxide. p < 0.05). However, compared with the model group, the FPDFVYK and APDTRLF peptides significantly increased BDNF mRNA expression, by 1.02 and 1.16 times, respectively, compared with the model group ( ). p (< 0.05), which can effectively exert neuroprotective effects. Therefore, FPDFVYK and APDTRLF may exert protective effects in PC12 cells damaged by oxidative stress by activating CREB and increasing BDNF expression levels.

[0040] In summary, the experiments in section 3.3 show that the above-mentioned peptides play a role in neuroprotection by activating the Nrf2 / HO-1 pathway. In addition, they may also play a protective role in PC12 cells damaged by oxidative stress by activating CREB and increasing the expression level of BDNF.

Claims

1. A neuroprotective polypeptide, characterized in that, A polypeptide with any of the following sequences: The amino acid sequence of the first polypeptide is FPDFVYK; The amino acid sequence of the second polypeptide is APDTRLF.

2. The use of the neuroprotective polypeptide according to claim 1 in the preparation of antioxidant drugs.

3. The use of the neuroprotective polypeptide of claim 1 in the preparation of anti-inflammatory drugs.

4. The use of the neuroprotective polypeptide of claim 1 in the preparation of a medicament for the prevention and treatment of neurodegenerative diseases.

5. The application according to claim 2, characterized in that, The antioxidants mentioned refer to reducing the levels of reactive oxygen species and malondialdehyde in the body, as well as enhancing the activity of superoxide dismutase and catalase in the body.

6. The application according to claim 3, characterized in that, The anti-inflammatory effect is to reduce the levels of cellular inflammatory factors such as tumor necrosis factor α, interleukin-6, interleukin-1β, and nitric oxide.

7. The application according to claim 4, characterized in that, The prevention and treatment of neurodegenerative diseases is achieved by reducing acetylcholinesterase activity, upregulating the expression of neurotrophic factors, thereby reducing nerve cell damage and enhancing memory.

8. The application according to claim 4, characterized in that, The neurodegenerative diseases mentioned are Alzheimer's disease, ischemic stroke, hemorrhagic stroke, brain trauma, or Parkinson's disease.

9. A polypeptide drug, characterized in that, The drug is prepared by adding pharmaceutically acceptable excipients to the neuroprotective polypeptide of claim 1.

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