1. An oyster peptide characterized by: the oyster peptide has the following amino acid sequence:

LAGELHQEQENYK, AIDTIINQK, DSYVGDEAQSK, PGTTEDEPVK, ETVIDTIQK, DLESQLK, NAETELGETSQR, EYDESGPSIVHR, DSDLEGHPTPR, HDNPGDLGDLH, AQCEMEPNH, ESAGIHETT or NTVLSGGTT.

2. Use of the oyster peptide according to claim 1, wherein: the use of one or more of the amino acid sequences of claim 1 for the alleviation or prevention or treatment of alcoholic liver injury.

3. Use of oyster peptide according to claim 2, characterized in that: the application of one or more amino acid sequences as a single active ingredient in preparing special medical food for preventing and treating alcoholic liver injury.

Background

With the development of national economy and the improvement of the living standard of people, the drinking population in China is getting stronger, and the number of patients with Alcoholic Liver Disease (ALD) is also increasing year by year. Alcoholic liver disease is a liver disease caused by long-term drinking, and it is initially steatosis of liver cells, and further progresses to alcoholic hepatitis and hepatic fibrosis, finally resulting in cirrhosis. The data show that more than 90 percent of the patients with severe alcohol drinking have fatty liver to a certain degree, 10 to 35 percent of the patients with severe alcohol drinking can develop alcoholic hepatitis, and 8 to 20 percent of the patients with severe alcohol drinking can develop cirrhosis. Epidemiological investigation in various parts of China shows that the prevalence rate of ALD of people in Hunan province in 2005 is 4.36%, the prevalence rate of ALD of people in Liaoning province in 2007 is 6.10%, and the prevalence rate of ALD of people in Guiyang city in 2009 is 10.99%, and the prevalence rate tends to increase year by year.

At present, the alcoholic liver disease is temporarily treated without specific medicines and cure treatment methods, alcohol withdrawal is still the key for treating and preventing the alcoholic liver disease, the understanding of people on the harm of excessive drinking behaviors is enhanced, the health screening of drinking people is enhanced, and early treatment is discovered as soon as possible. When obvious liver injury occurs, clinical treatment is mainly performed, common clinical treatment means of alcoholic liver diseases are drug intervention treatment, but long-term administration can increase the burden of the liver and generate certain side effects on the organism, so more and more scholars are dedicated to extracting safe and effective active substances from natural products for treating the alcoholic liver diseases.

Oyster, commonly known as oyster, is one of four cultured shellfish in China. The oyster has rich protein content and perfect amino acid composition, and free amino acid contains rich taurine. Besides being eaten, the oyster is also a traditional marine Chinese medicinal material, is a first marine animal resource for medicine and food use published in China, has the efficacies of diminishing inflammation, detoxifying, protecting liver, benefiting gallbladder, reducing blood fat and the like, and attracts more and more students' attention as a marine medicament for treating diseases and building bodies. At present, oysters are proved to have the effects of protecting liver and reducing blood fat, and researches show that oyster water-soluble polysaccharide extracts can reduce the level of alanine Aminotransferase (ALT), aspartate Aminotransferase (AST) and Malondialdehyde (MDA) in the serum of mice with acute liver injury. In recent years, various liver-protecting health products with oysters as main components have been developed at home and abroad, such as oyster taurine vitamin C capsules developed by the Wehainan Bay group, Shenzhen Jinzun oyster soybean peptide carnitine oral liquid developed by the Shenzhen Hawang group, and oyster powder produced by Norway Bjorge Ocean company, which have the efficacy of protecting the liver. In conclusion, oysters are widely accepted by scholars at home and abroad as a functional food for protecting liver and reducing blood fat, but the existing products are all oyster crude extracts compounded with other components, and the specific efficacy source is not clear. The invention adopts an enzyme technology and an ultrafiltration technology to prepare the oyster peptide with low molecular weight, identifies the amino acid sequence of the oyster peptide through separation and purification, applies the oyster peptide as a single active component to the research of alcoholic liver injury, and has certain innovation.

Disclosure of Invention

The invention aims to extract oyster peptide and application thereof in alcoholic liver injury

In order to achieve the purpose, the invention adopts the technical scheme that:

an oyster peptide is the following amino acid sequence:

LAGELHQEQENYK, AIDTIINQK, DSYVGDEAQSK, PGTTEDEPVK, ETVIDTIQK, DLESQLK, NAETELGETSQR, EYDESGPSIVHR, DSDLEGHPTPR, HDNPGDLGDLH, AQCEMEPNH, ESAGIHETT or NTVLSGGTT.

The application of the oyster peptide and the application of one or more of the amino acid sequences in relieving and preventing alcoholic liver injury.

The application of one or more amino acid sequences as a single active ingredient in preparing special medical food for preventing and treating alcoholic liver injury.

The invention has the following advantages:

1. the oyster peptide disclosed by the invention has a definite amino acid sequence composition.

2. The oyster peptide disclosed by the invention has a relatively obvious protective effect on an alcoholic liver injury model mouse. And the experimental results show that: the oyster peptide low, medium and high dose groups can obviously reduce ALT and AST levels in serum of a model mouse, improve SOD and GSH activities, reduce MDA content and regulate the levels of inflammatory factors IL-1 beta, IL-6 and TNF-alpha. The oyster peptide disclosed by the invention has the functions of protecting liver and relieving alcoholism.

Drawings

FIG. 1 shows a first-order mass spectrum of oyster peptide NAETELGETSQR according to an embodiment of the present invention

Fig. 2 is a graph showing the effect of oyster peptide provided by the present invention on GSH content in mouse liver tissue, note: different letters indicate that a very significant difference between groups was achieved, i.e. P < 0.01.

FIG. 3 shows the effect of oyster peptide on SOD content in mouse liver tissue, note: different letters indicate that a very significant difference between groups was achieved, i.e. P < 0.01.

Fig. 4 is a graph showing the influence of oyster peptide provided by the embodiment of the present invention on the MDA content in mouse liver tissue, note that: different letters indicate that a very significant difference between groups was achieved, i.e. P < 0.01.

FIG. 5 shows the effect of oyster peptide on IL-1. beta. and IL-6 content in mouse liver tissue, note: different letters indicate that very significant differences between groups were achieved, i.e. P <0.05 and P < 0.01.

FIG. 6 shows the effect of oyster peptide on TNF- α content in mouse liver tissue, note: different letters indicate that a very significant difference between groups was achieved, i.e. P < 0.01.

FIG. 7 shows the effect of oyster peptides on AST and ALT in mouse serum provided by the present invention, and the following are injected: different letters indicate that a very significant difference between groups was achieved, i.e. P < 0.01.

Detailed Description

The invention is further illustrated by the following examples. The following examples are presented to further illustrate embodiments of the present invention, and it should be understood that the embodiments described herein are for purposes of illustration and explanation only and are not intended to limit the invention.

Example 1

The oyster peptide related by the invention is prepared by an enzyme technology from oyster homogenate, taking oyster peptide with the sequence of ETVIDTIQK as an example, the specific obtaining process is as follows:

the oyster homogenate is hydrolyzed by protease to prepare oyster enzymolysis liquid, the enzymolysis liquid is ultrafiltered and separated by a 3000Da ultrafiltration membrane, freeze drying is carried out to obtain oyster peptide with low molecular weight, then the oyster peptide is separated and purified by gel chromatography, the separated peptide segment directly enters a Thermo Scientific Q exact mass spectrometer for detection, 25 ion peaks are obtained in total, and the mass spectrogram is shown in figure 1. And performing secondary ion analysis on the ions with the highest content to determine that the ions are double-charge ions, wherein the amino acid sequence of the ions is identified to be NAETELGETSQR, and the molecular weight of the ions is 1335.64 Da.

Application example: protective effect of oyster peptide on alcoholic liver injury model mice

1. Experimental animals: c57BL/6 mice, male, 6-8 weeks old, with a body weight of 18-22 g.

2. Grouping experiments: the experimental mice are randomly divided into 6 groups, each group comprises 12 mice, and the groups respectively comprise a blank group, a model group, a positive control group, and oyster peptide low, medium and high dose groups. The oyster peptides obtained in the embodiment are intragastrically administered according to low, medium and high dose groups, the doses are respectively 120mg/kg/d, 240mg/kg/d and 480mg/kg/d, the intragastrically administered volume is 10mL/kg, and the dose group in the oyster peptides is 10 times of the daily dose of the full-nutrition powder for the similar liver diseases in the market; the positive control group bifendate gavage dose is 10 mg/kg/d; the blank group and the model group were administered with distilled water of the same volume per day, and after 1 hour, 5 groups except the blank group were continuously administered with ethanol having a gastric lavage concentration of 50% in accordance with 10mL/kg BW, and molded for 42 d. After the last molding, fasting for 16h, taking blood in a 2ml centrifuge tube by an eye ball removing method, and separating serum; after blood sampling, mice are sacrificed by cervical dislocation, livers are taken out by timely autopsy, left leaves are fixed, the rest is homogenized, and detection and pathological histological examination of each index are carried out.

3. Measurement indexes are as follows: respectively measuring the contents of MDA, reduced Glutathione (GSH), superoxide dismutase (SOD), tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta) and interleukin-6 (IL-6) in liver tissue homogenate of each group of mice by using a corresponding kit; ALT and AST contents in serum.

4. Statistical analysis: SPSS18.0 statistical software is applied, the metering mode is represented by ' mean plus or minus standard deviation ', a one-factor variance method is adopted for comparison among groups, an LSD method is used for analyzing when the variances among the groups are two-by-two compared and the method of Dunnett's is used for analyzing when the variances are not uniform.

5. Results of the experiment

5.1 Effect of oyster peptides on GSH and SOD in liver tissue of model mice.

As can be seen from fig. 2 and 3, the GSH and SOD contents of the model group were significantly reduced (P <0.01) compared to the blank group, and the GSH and SOD contents of the bifendate group and the oyster peptide low, medium and high dose groups were increased to different degrees compared to the model group, wherein the oyster peptide low dose group was able to significantly increase the GSH content (P <0.01) compared to the model group, and the oyster peptide high dose group was able to significantly increase the SOD content (P <0.01) compared to the model group.

5.2 Effect of oyster peptide on MDA in liver tissue of model mice.

As can be seen from fig. 4, the MDA content in the model group was significantly increased compared to the blank group (P <0.01), and the low, medium and high dose groups of bifendate and oyster peptide both significantly decreased the MDA content in the liver tissue of the mice compared to the model group (P < 0.01).

5.3 Effect of oyster peptides on inflammatory factors in liver tissue of model mice.

As can be seen from fig. 5, the content of IL-1 β in the model group was increased (P <0.01) compared to the blank group, and the low, medium and high dosage groups of oyster peptide could significantly decrease IL-1 β (P <0.01) compared to the model group; in addition, the content of IL-6 in the bifendate group and the oyster peptide high-dose group is remarkably reduced compared with that in the model group (P < 0.05).

As can be seen from FIG. 6, the TNF-. alpha.content was increased in the model group compared to the blank group, and the TNF-. alpha.content was significantly decreased in the bifendate group and the oyster peptide low, medium and high dose groups compared to the model group (P < 0.01).

5.4 Effect of oyster peptides on AST and ALT in serum of model mice.

As can be seen from fig. 7, the AST and ALT contents were increased in the model group compared to the blank group (P <0.01), and the AST and ALT contents were significantly decreased in the low, medium and high dose groups of bifendate and oyster peptide (P <0.01) compared to the model group.

The embodiment proves that the oyster peptide has a protective effect on mice with alcoholic liver injury, can reduce the ALT and AST content in the serum of the mice, improve the contents of peroxidase SOD and GSH, reduce the MDA content, relieve the oxidative stress of organisms and reduce the levels of inflammatory factors IL-1 beta, IL-6 and TNF-alpha in the liver tissues of the mice.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be able to cover the technical solutions and the inventive concepts of the present invention within the technical scope of the present invention.