An oyster peptide that enhances intestinal barrier function and improves intestinal inflammation, its preparation method and application

Abstract

This invention belongs to the field of biotechnology, specifically relating to an oyster peptide that enhances intestinal barrier function and improves intestinal inflammation, its preparation method, and its applications. The oyster peptide provided by this invention can alleviate colitis symptoms such as weight loss, colon shortening, and edema in mice, reduce disease activity index (DAI) levels, and regulate the balance of oxidative stress and inflammatory factors. Furthermore, LC-MS / MS technology was used to analyze the peptide sequence of the oyster peptide. Through this precise analytical process, key small molecule peptides with significant effects on enhancing intestinal barrier function and improving intestinal inflammation were successfully screened. This discovery provides important evidence for a deeper understanding of the effects of oyster peptides on enhancing intestinal barrier function and improving intestinal inflammation, and also provides new ideas for subsequent drug development and clinical treatment.

Description

Technical Field

[0001] This invention belongs to the field of biotechnology, specifically relating to an oyster peptide that enhances intestinal barrier function and improves intestinal inflammation, its preparation method, and its application. Background Technology

[0002] The gut is not only the main organ for digesting and absorbing nutrients, but also the largest immune organ and barrier organ in the human body. The intestinal mucosal barrier is composed of mechanical, chemical, immune, and biological barriers, and its structural integrity and normal function are key to maintaining bodily health. Once the intestinal barrier function is impaired, leading to increased intestinal permeability (i.e., "leaky gut"), it will trigger local and even systemic chronic low-grade inflammation, which has been proven to be an important inducing and aggravating factor for many chronic diseases such as inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), metabolic syndrome, autoimmune diseases, and nervous system diseases.

[0003] Currently, clinical interventions for intestinal barrier dysfunction and intestinal inflammation mainly include aminosalicylic acid preparations, glucocorticoids, immunosuppressants, and biologics. While these drugs have some efficacy, they generally suffer from significant side effects, poor targeting, difficulty in precisely repairing the damaged intestinal barrier, and a tendency to disrupt the balance of gut microbiota. Their high cost also limits their effectiveness in fundamentally repairing and enhancing intestinal barrier function. Therefore, developing a preventive or adjunctive treatment strategy that can target and enhance intestinal barrier function, is safe and has no side effects, and is derived from natural foods has become a research hotspot and urgent need in the fields of nutritional medicine, preventive medicine, and functional foods.

[0004] Oysters, a traditional food and medicine, have a long history of use in my country. The Compendium of Materia Medica records that they can "nourish yin and blood, calm the nerves and detoxify." Modern research shows that oyster meat is rich in high-quality protein, taurine, zinc, selenium, and other nutrients, possessing various physiological functions such as anti-oxidation, immune enhancement, and anti-fatigue. Although there are some research reports on the improvement of intestinal health by marine peptides (such as fish skin collagen peptides and sea cucumber peptides), research on oyster-derived bioactive peptides, especially those clearly linking their dual effects of "enhancing intestinal barrier function" and "improving intestinal inflammation," and systematically elucidating their preparation methods, structural characteristics, and molecular mechanisms, remains lacking. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide an oyster peptide that enhances intestinal barrier function and improves intestinal inflammation, as well as its preparation method and application. By identifying and virtually screening active peptides, active peptides that enhance intestinal barrier function are prepared, thereby improving intestinal protection, reducing damage to the intestinal barrier from external toxins and reducing the invasion of toxins into the human body through the intestines, and avoiding the side effects of taking drugs such as azathioprine and cyclosporine, effectively helping patients with impaired intestinal barrier and intestinal inflammation.

[0006] The purpose of this invention is to provide the preparation of oyster peptides and their application in drugs that regulate and enhance intestinal barrier function and improve intestinal inflammation, so as to solve the problems existing in the prior art.

[0007] The first aspect of this invention is to provide a method for preparing oyster peptides, comprising the following steps: Oysters were subjected to combined enzymatic hydrolysis using papain and neutral protease, and the supernatant was collected.

[0008] In some embodiments of the present invention, the oyster is a triploid Hong Kong oyster.

[0009] In some embodiments of the present invention, the total amount of papain and neutral protease added is 1% to 3% of the mass of the oyster raw material.

[0010] In some embodiments of the present invention, the mass ratio of papain to neutral protease is 1:(1~3). In some embodiments of the present invention, the enzyme activities of both the papain and the neutral protease are not less than 100,000 U / g. In some embodiments of the present invention, the oysters are homogenized with water at a volume ratio of 1:(10~20).

[0011] In some embodiments of the present invention, the enzymatic hydrolysis temperature is 40~55°C.

[0012] In some embodiments of the present invention, the enzymatic hydrolysis time is 2 to 4 hours.

[0013] In some embodiments of the present invention, the step of removing precipitate is included before collecting the supernatant, which can be achieved by centrifugation or filtration to remove residual fine solid particles, colloids, partially denatured proteins and a small amount of flocculents.

[0014] In some embodiments of the present invention, the supernatant is passed through a nanofiltration membrane to remove inorganic salts, and the resulting clear solution is spray-dried to obtain a powder, which is oyster peptide.

[0015] Specifically, the enzymatic hydrolysis method includes: adding defatted oyster meat powder to a 1:10~20 volume ratio of deionized water and homogenizing it further using a high-speed homogenizer; adjusting the pH value to between 6.8 and 7.5; adding approximately 1%~3% of a mixture of papain and neutral protease, wherein the ratio of papain to neutral protease is 1:1~3; the enzymatic hydrolysis temperature is 40~55℃; the enzymatic hydrolysis time is 2~4 hours; during the enzymatic hydrolysis process, attention should be paid to stirring and monitoring the pH value; and the enzyme is inactivated by maintaining the temperature at 90~95℃ for about 30 minutes.

[0016] Specifically, the defatted oyster processing method is as follows: After pulverizing the oyster meat or dried oyster meat, mix the oyster meat powder with sufficient distilled water and stir thoroughly to form a uniform suspension. Slowly heat to 85-95℃, and gently stir at this temperature for 20-40 minutes. Avoid vigorous boiling to prevent increased emulsification. After stopping heating, transfer the mixture to a graduated cylinder or a standing container, cool to room temperature or refrigerate at 4℃ for several hours, and carefully remove the upper fat layer.

[0017] In a second aspect, the present invention provides an oyster peptide prepared by the preparation method of the first aspect of the present invention.

[0018] In some embodiments of the present invention, the oyster peptides include VAPEEHPV (SEQ ID NO: 1), LVGLLGFH (SEQ ID NO: 2), GFAGDDAPR (SEQ ID NO: 3), VAPEEHPVL (SEQ ID NO: 4), ILPGE (SEQ ID NO: 5), LVL (SEQ ID NO: 6), LPGEL (SEQ ID NO: 7), IAPPERKY (SEQ ID NO: 8), GSPGPVGPAG (SEQ ID NO: 9), and TTPIP (SEQ ID NO: 10).

[0019] In some embodiments of the present invention, the content (wt%) of each peptide segment of the oyster peptide is as follows: VAPEEHPV (SEQ ID NO: 1) 7~8%; LVGLLGFH (SEQ ID NO: 2) 5~6%; GFAGDDAPR (SEQ ID NO: 3) 3~4%; VAPEEHPVL (SEQ ID NO: 4) 2~4%; ILPGE (SEQ ID NO: 5) 1.5~2.5%; LVL (SEQ ID NO: 6) 1.5~2.5%; LPGEL (SEQ ID NO: 7) 1.5~2.5%; IAPPERKY (SEQ ID NO: 8) 1.5~2.5%; GSPGPVGPAG (SEQ ID NO: 9) 1.5~2.5%; TTPIP (SEQ ID NO: 10) 1.5~2.5%.

[0020] A third aspect of the present invention provides the use of the oyster peptide described in the second aspect of the present invention in the preparation of a medicament for enhancing intestinal barrier function and improving intestinal inflammation.

[0021] In some embodiments of the present invention, the medicament includes pharmaceutically acceptable excipients.

[0022] In some embodiments of the present invention, the intestinal inflammation includes colitis.

[0023] In some embodiments of the present invention, the colitis includes ulcerative colitis.

[0024] In a fourth aspect, the present invention provides a medicament comprising the oyster peptide described in the second aspect of the present invention.

[0025] In some embodiments of the present invention, the medicament includes pharmaceutically acceptable excipients.

[0026] In some embodiments of the present invention, the pharmaceutically acceptable excipients include at least one of the following: propellants, colorants, binders, disintegrants, fillers, lubricants, wetting agents, osmotic pressure regulators, stabilizers, flow aids, flavoring agents, preservatives, suspending agents, coating materials, fragrances, anti-adhesion agents, penetration enhancers, pH adjusters, buffers, plasticizers, surfactants, foaming agents, defoamers, thickeners, encapsulating agents, humectants, absorbents, diluents, flocculants and anti-flocculators, filter aids, and release inhibitors.

[0027] The pharmaceutically acceptable excipients mentioned above are generally recognized for use in this purpose and as inactive ingredients in the pharmaceutical preparation. Compilations of pharmaceutically acceptable excipients can be found in reference books such as the *Handbook of Pharmaceutical Excipients* (2nd edition, edited by A. Wade and PJ Weller; published by the American Pharmaceutical Association, Washington and The Pharmaceutical Press, London, 1994) and the *Pharmacopoeia of the People's Republic of China - List of Pharmaceutical Excipients*.

[0028] In some embodiments of the present invention, the dosage form of the drug includes a solid dosage form, a liquid dosage form, a paste dosage form, or an emulsion dosage form.

[0029] The beneficial effects of this invention are: The oyster peptides provided in this invention can alleviate colitis symptoms such as weight loss, colon shortening, and edema in mice, reduce disease activity index (DAI) levels, and regulate the balance of oxidative stress and inflammatory factors. Furthermore, LC-MS / MS technology was used to analyze the peptide sequences of the oyster peptides. Through this precise analytical process, key small molecule peptides with significant effects on enhancing intestinal barrier function and improving intestinal inflammation were successfully screened. This discovery provides important evidence for a deeper understanding of how oyster peptides enhance intestinal barrier function and improve intestinal inflammation, and also offers new insights for subsequent drug development and clinical treatment. Attached Figure Description

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 The image shows the total ion chromatogram of oyster peptides.

[0031] Figure 2 The results show the effects of oyster peptides on body weight and disease activity index (DAI) in DSS-induced acute colitis mice (n=10). Figure A shows the daily body weight changes in each group; Figure B shows the DAI scores of each group from day 8 to day 14; Figure C shows the fecal characteristics of each group from day 8 to day 14; Figure D shows the rectal bleeding in each group from day 8 to day 14. Results are expressed as mean ± SD (n=10); ##<0.01, ###<0.001 compared to the Control group; *<0.05, **<0.01, ***<0.001 compared to the DSS group.

[0032] Figure 3 The results show the effects of oyster peptides on colon length, colon index, and spleen index in mice (n=10). A represents a representative colonogram for each group; B represents colon length for each group; C represents colon index results for each group; and D represents spleen index results for each group. Results are expressed as mean ± SD (n=10). ###<0.001 compared to the Control group; *<0.05, **<0.01, ***<0.001 compared to the DSS group.

[0033] Figure 4 HE staining image of pathological changes in mouse colon tissue caused by oyster peptides.

[0034] Figure 5Figure showing the effect of oyster peptides on intestinal barrier proteins in mice. (AC) Relative expression levels of intestinal tight junction proteins Claudin-1 and Occludin, with GAPDH as an internal control; results are expressed as mean ± SD (n = 4); # < 0.05, ## < 0.01 compared with the control group; * < 0.05 compared with the DSS group.

[0035] Figure 6 The figure shows the effect of oyster peptides on inflammatory factors in the colonic tissue of mice with DSS-induced colitis (n=10). In the figure, A represents TNF-α expression; B represents IL-1β expression; and C represents IL-6 expression. Results are expressed as mean ± SD (n=10); ###<0.001 compared with the Control group; ***<0.001 compared with the DSS group.

[0036] Figure 7 The figure shows the effect of oyster peptides on oxidative stress parameters in colonic tissue of DSS-induced colitis mice (n=10). In the figure, A represents MPO expression; B represents SOD expression; C represents MDA expression; and D represents GSH-PX expression. Results are expressed as mean ± SD (n=10); ###<0.001 compared to the Control group; *<0.05, ***<0.001 compared to the DSS group.

[0037] Figure 8 The figure shows the effect of oyster peptides on the expression of MAPK signaling pathway proteins. (AD) Relative expression levels of P38, P-P38, ERK, P-ERK, JNK, and P-JNK in the cytoplasm, with GAPDH as an internal control. Results are expressed as mean ± SD (n=4), ###<0.001 compared with the control group; *<0.05, ***<0.001 compared with the DSS group.

[0038] Figure 9 Figure 1 shows the results of short-chain fatty acid content analysis in mouse feces. (A) Acetic acid content. (B) Propionic acid content. (C) Butyric acid content. (D) Isobutyric acid content. (E) Valeric acid content. (F) Isovaleric acid content. Results are expressed as mean ± SD (n = 10); ### < 0.001 compared with the Control group; *** < 0.001 compared with the DSS group. Detailed Implementation

[0039] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0040] The oysters used in the preparation of oyster peptides in this invention are mainly triploid Hong Kong oysters. Dextran sulfate sodium salt (molecular weight 36,000-50,000) was purchased from Meilun Bio (Liaoning, China); a fecal occult blood qualitative detection kit (o-toluidine method) was purchased from Edison Biotechnology Co., Ltd. (Jiangsu, China); a mouse TNF-α, IL-6, IL-1β enzyme-linked immunosorbent assay (ELISA) kit was purchased from Edison Biotechnology Co., Ltd. (Jiangsu, China); and an MPO, SOD, MDA, GSH-Px activity detection kit was purchased from elabscience (Wuhan, Hubei).

[0041] The instruments and equipment used in this embodiment are as follows: Mithras LB940 multi-functional microplate reader (Thermo Fisher Scientific, USA); paraffin embedding machine and microtome (Guangzhou Yuanqi Health Technology Co., Ltd.); optical microscope (Olympus Corporation, Japan).

[0042] Example 1: Preparation of Oyster Peptides Add 15 volumes of deionized water to the defatted oyster meat paste and homogenize it further using a high-speed homogenizer. Adjust the pH to approximately 7.2. Add approximately 2% (by dry weight of the substrate) of a mixture of papain and neutral protease, with a papain to neutral protease ratio of 1:2. The enzymatic hydrolysis temperature is 45℃, and the hydrolysis time is 3 hours. Papain and neutral protease were purchased from Nanning Pangbo Biotechnology Co., Ltd., with papain and neutral protease having enzyme activities of 200,000 U / g and 200,000 U / g respectively. During the enzymatic hydrolysis process, pay attention to stirring and monitoring the temperature and pH. Inactivate the enzymes by maintaining a temperature of 90-95℃ for about 30 minutes. After cooling, centrifuge or filter to remove residual fine solid particles, colloids, some denatured proteins, and a small amount of flocculent matter. Then, treat the liquid through a nanofiltration membrane to remove inorganic salts. The resulting clear solution is spray-dried to obtain the powder, which is the oyster peptide.

[0043] Example 2: Nutritional composition and physicochemical detection of oyster peptides The nutritional composition of OPs was determined, including the determination of protein content using the Kjeldahl method (referring to GB 5009.5-2016 "National Food Safety Standard - Determination of Protein in Foods"); the determination of moisture content using the direct drying method (referring to GB 5009.3-2016 "National Food Safety Standard - Determination of Moisture in Foods"); and the determination of fat content using the acid hydrolysis method (referring to GB 5009.3-2016 "National Food Safety Standard - Determination of Moisture in Foods"). Analysis of heavy metals and pesticide residues was conducted in accordance with national standards.

[0044] Experimental results: The nutritional composition and heavy metal content of OPs are shown in Table 1. After enzymatic hydrolysis, OPs had the highest crude protein content, reaching 70.05%, followed by ash at 16.82%, fat at 3.49%, and moisture at 1.69%. Heavy metal content in OPs was also determined, and all results met the national food safety standard limits for contaminants in food (GB2762-2022).

[0045] Table 1 Physicochemical properties of OPs

[0046] Example 3 Identification of the major peptide sequence of oyster peptides LC-MS / MS method for peptide identification: Peptide samples are identified by extraction, reductive alkylation, desalting, and LC-MS / MS mass spectrometry. The identification results are obtained by matching the data with Byonic software from Beijing Biotech Biotechnology Co., Ltd. (Beijing, China).

[0047] Experimental results: All peptides in the OPs were identified by LC-MS / MS. The total ion spectrum is shown below. Figure 1 As shown in the figure, a total of 994 peptides were identified in the OPs, with molecular weights ranging from 302 to 2000 Da. The sequences, masses, contents, and bioactivities of the 10 most abundant peptides in the OPs are shown in Table 2.

[0048] Table 2. Sequence, length, mass, and content of the 10 most abundant peptides in OPs.

[0049] Example 4: Animal experimental verification of oyster peptides in improving intestinal inflammation and enhancing the intestinal barrier By establishing a 2.5% DSS-induced colitis mouse model, this study elucidates the ameliorative effects and related mechanisms of OPs on colitis from multiple perspectives, including colonic symptoms, pathological changes, short-chain fatty acids, and gut microbiota. It also identifies specific peptide sequences that have the effect of improving UC, providing a scientific basis for the development of oyster-based gut health products.

[0050] 1. Experimental Methods 1) Animal modeling and experimental grouping Mice were housed in a controlled environment with a temperature of 23±1℃, relative humidity of 55±5%, and a 12-hour light-dark cycle. They had free access to food and water. After one week of acclimatization, they were grouped into groups of five mice per cage, with bedding changed twice a week. The animals used in this experiment were healthy 6-week-old male C57BL / 6 mice, provided by Yoda Biotechnology Co., Ltd. (Guangzhou, China).

[0051] Fifty mice were randomly divided into five groups of ten each: a control group (control) administered saline by gavage; a model group (DSS) administered saline by gavage; a low-dose group (DSS+OPs-L) administered OPs containing 100 mg / kg body weight (BW) by gavage; a medium-dose group (DSS+OPs-M) administered OPs containing 200 mg / kg body weight (BW) by gavage; and a high-dose group (DSS+OPs-H) administered OPs containing 500 mg / kg body weight (BW) by gavage. Administered medications by gavage at fixed times daily for 14 days. The control group received normal feed and drinking water throughout the experiment. From day 8 onwards, the other four groups received 2.5% (v / v) DSS in their drinking water for free access for seven days. The DSS solution was freshly prepared every two days. At the end of the experiment, mice were euthanized by cervical dislocation, and the colon, spleen, and colonic contents were collected for subsequent analysis.

[0052] 2) Disease Activity Index The mice's weight was recorded daily. Starting from day 8, each mouse was scored with a Disease Activity Index (DAI), which included weight loss, fecal characteristics, and blood in the stool, as shown in Table 3.

[0053] Table 3 Disease Activity Index (DAI) Scoring Criteria

[0054] 3) Colonic histopathology The distal colon tissue was rinsed with phosphate-buffered saline (PBS), fixed with 4% paraformaldehyde, then embedded in paraffin, sectioned, and stained with red ochre stain. The structures were observed and photographed under a microscope for analysis of the colitis tissue.

[0055] 4) Measurement of inflammatory factors and oxidative stress parameters in colonic tissue TNF-α, IL-6, and IL-1β in colon tissue were detected using their respective enzyme-linked immunosorbent assay (ELISA) kits, according to the manufacturer's instructions. Oxidative stress markers in colon tissue, including MPO, SOD, MDA, and GSH-Px, were also detected using appropriate kits.

[0056] 5) Determination of related protein expression Western blot (WB) was used to detect the expression levels of Occludin, Claudin-1, p38, p-p38, JNK, p-JNK, ERK, and p-ERK proteins in colon tissue. Colon tissue samples were collected, total protein was extracted, and protein concentration was determined using a BSA protein quantification kit. Equal volumes of protein samples were separated by SDS-PAGE gel electrophoresis and transferred to PVDF membranes. The membranes were then blocked with blocking buffer containing 5% bovine serum albumin (BSA) at room temperature for 3–4 hours. After blocking, the membranes were incubated overnight at 4°C with the corresponding primary antibodies (Occludin, Claudin-1, p38, p-p38, JNK, p-JNK, ERK, p-ERK, and GAPDH). After washing with TBST, the membranes were incubated with secondary antibodies at room temperature for 2 hours, followed by another wash. Finally, chemiluminescence immunoassay was used for development, and the gray values ​​of the target bands were analyzed using ImageJ software. GAPDH was used as an internal control for standardization, and the relative expression levels of each protein were calculated.

[0057] 2. Experimental Results 1) Ops improves general symptoms in mice with colitis The results are as follows Figure 2 As shown in Figure AB, the normal control group mice were healthy throughout the study period, exhibiting normal, granular stools, good mental state, agile behavior, glossy black fur, and continuous weight gain, with a DAI score of 0. Conversely, the model group mice, after drinking DSS solution, began to lose weight from day 9 of model initiation. After intervention with OPs, the weight loss trend was alleviated in a dose-dependent manner (P<0.01 in low and medium dose groups, P<0.001 in the high dose group). Results are as follows... Figure 2 As shown in the CD, further evaluation of fecal characteristics and rectal bleeding revealed that mice in the DSS model group developed symptoms such as loose stools, positive fecal occult blood, and lethargy starting from day 12. OPs intervention improved these symptoms in colitis mice; high-dose OPs significantly reduced abnormal fecal consistency (P<0.05), while medium- and high-dose OPs significantly alleviated rectal bleeding (P<0.001).

[0058] 2) OPs improve intestinal atrophy and edema in colitis mice The results are as follows Figure 3 As shown in Figure AB, compared with the control group, the colon length of mice in the model group was significantly shortened (P<0.001), with an average shortening of 3.7 cm. After intervention with Ops drug administration, the shortening of colon length was alleviated, and the colon length of mice in the low, medium, and high dose groups recovered to 4.36 cm, 4.6 cm, and 4.83 cm, respectively. Figure 3As shown in the CD, compared with the control group, the colon of DSS-induced colitis mice was enlarged and shortened, and both the spleen index and colon index were significantly increased (P<0.001). After OPs intervention, the colon enlargement was improved. Figure 3 In the middle A region, the colonic index decreased in a dose-dependent manner, with the effect of high-dose OPs being the most significant (P<0.001). Furthermore, high-dose OPs also significantly reduced the spleen index (P<0.01).

[0059] 3) OPs improve pathological damage in mice with colitis The results are as follows Figure 4 As shown, these are representative HE-stained sections of colon tissue from each group of mice. In the normal control group, the colonic mucosa structure was intact and clear, with orderly arrangement of crypts and glands, abundant goblet cells, and no obvious inflammatory cell infiltration. In contrast, the model group showed severe damage to the colonic epithelial structure, complete destruction of crypts, a large loss of goblet cells, and extensive inflammatory cell infiltration in the lamina propria. After intervention with OPs, compared with the model group, the high-dose OPs group showed significantly reduced inflammatory cell infiltration in the colonic tissue, milder epithelial structural damage, some recovery of goblet cell numbers, and relatively intact crypt and gland structures.

[0060] 4) OPs maintain the tightness of the intestinal barrier. like Figure 5 As shown in the AC, compared with the control group, the expression of tight junction proteins Claudin-1 (P<0.01) and Occludin (P<0.05) in the colon tissue of the model group was significantly reduced. Compared with the model group, high-dose OPs significantly increased the expression of Claudin-1 (P<0.05); in addition, medium and high-dose OPs also significantly increased the expression level of Occludin (P<0.05).

[0061] 5) Ops inhibited the levels of peripheral pro-inflammatory factors (TNF-α, IL-6, and IL-1β) in colitis mice. The results are as follows Figure 6 As shown in the AC, compared with the control group, the expression levels of pro-inflammatory factors TNF-α, IL-6 and IL-1β in the colon tissue of the model group were significantly increased after continuous drinking of DSS solution for 7 days (P<0.001). Compared with the model group, medium and high doses of OPs significantly reduced the expression of TNF-α, IL-6 and IL-1β (P<0.001).

[0062] 6) Ops enhances the activity of antioxidant enzymes (SOD, GSH-PX) and inhibits the production of MPO and MDA. The results are as follows Figure 7As shown in the AD diagram, compared with the control group, the levels of MPO and MDA in the colon tissue of mice in the DSS model group were significantly increased (P<0.001), while the activities of SOD and GSH-PX were significantly decreased (P<0.001). Compared with the model group, the expression levels of MPO and MDA were significantly decreased (P<0.001); at the same time, SOD activity increased in a dose-dependent manner (P<0.05 in the low-dose group, P<0.001 in the medium and high-dose groups), and GSH-PX activity also increased significantly after OPs intervention (P<0.001).

[0063] 7) OPs alleviate colonic inflammation by inhibiting the MAPK signaling pathway. The results are as follows Figure 8 As shown, compared with the control group, the phosphorylation levels of key MAPK signaling pathway proteins p38, ERK, and JNK in the colon tissue of model group mice were significantly increased (P<0.001). After intervention with OPs, the expression of p-p38 / p38 decreased in a dose-dependent manner compared with the model group (low-dose group P<0.05, medium-dose group P<0.01, high-dose group P<0.001). At the same time, both medium and high doses of OPs could reduce the expression level of p-ERK / ERK (medium-dose group P<0.01, high-dose group P<0.001). In addition, both medium and high doses of OPs could also significantly reduce the expression of p-JNK / JNK (medium-dose group P<0.05, high-dose group P<0.001).

[0064] 8) Effects of OPs on short-chain fatty acids in mouse feces The results are as follows Figure 9 As shown, compared with the control group, the levels of propionic acid, butyric acid, isobutyric acid, valeric acid, and isovaleric acid in the feces of mice in the model group were significantly increased (P<0.001). Compared with the model group, the levels of the above short-chain fatty acids (propionic acid, butyric acid, isobutyric acid, valeric acid, and isovaleric acid) were significantly decreased after OPs intervention (P<0.001). In addition, low and medium doses of OPs intervention also significantly reduced the content of acetic acid (P<0.001).

[0065] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A method for preparing oyster peptides, characterized in that: Oysters were subjected to combined enzymatic hydrolysis using papain and neutral protease, and the supernatant was collected. The oysters mentioned are triploid Hong Kong oysters; The total amount of papain and neutral protease added is 1% to 3% of the oyster raw material mass; The mass ratio of papain to neutral protease is 1:1:(1~3). The enzyme activities of both papain and neutral protease are not less than 100,000 U / g.

2. The preparation method according to claim 1, characterized in that: The oysters were homogenized with water at a volume ratio of 1:(10~20).

3. The preparation method according to claim 2, characterized in that: The enzymatic hydrolysis temperature is 40~55℃; The enzymatic hydrolysis time is 2-4 hours.

4. The preparation method according to claim 3, characterized in that: The oysters mentioned are defatted oysters.

5. An oyster peptide, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 4.

6. The oyster peptide according to claim 5, characterized in that: The oyster peptides include VAPEEHPV, LVGLLGFH, GFAGDDAPR, VAPEEHPVL, ILPGE, LVL, LPGEL, IAPPERKY, GSPGPVGPAG, and TTPIP.

7. The use of the oyster peptide according to claim 5 or 6 in the preparation of a medicament for enhancing intestinal barrier function and improving intestinal inflammation.

8. The application according to claim 7 is characterized in that: The intestinal inflammation includes colitis.

9. A drug, characterized in that: The drug comprises the oyster peptide as described in claim 5 or 6.

10. The medicament according to claim 9, characterized in that: The drug includes pharmaceutically acceptable excipients.

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