Boletus brownii xylan palmitate as well as preparation method and application thereof

Abstract

The invention discloses boletus brownii xylan palmitate as well as a preparation method and application thereof. The boletus brownii xylan palmitate is xylan palmitate which is formed by alpha-(1-> 4)-xylose as a main chain, alpha-(1->)-glucose as a branch chain and palmitic acid molecules through ester bonds. The invention further discloses a preparation method of the boletus brownii xylan palmitate and application of the boletus brownii xylan palmitate in the aspect of immunoregulation. The boletus brownii xylan palmitate can be used as a dietary supplement or a food additive for immunodeficiency patients and tumor patients.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of food and biology, and particularly relates to a Suillus luteus xylan palmitate and a preparation method and application thereof. BACKGROUND

[0002] As a natural resource with both nutritional and medicinal values, edible fungi have their cell walls mainly containing polysaccharides with immunomodulatory, anti-tumor, anti-inflammatory and other biological activities, and the development and application of polysaccharides in the fields of functional foods and biological medicines have become a research hotspot. As an excellent mycorrhizal edible fungus, Suillus luteus is rich in polysaccharides, proteins, flavonoids, ergosterol and other active ingredients, and can be used for soil remediation by regulating soil microbial community diversity, enriching nutrients and reducing heavy metal content, and has a high comprehensive utilization value, providing a high-quality raw material basis for the development of active polysaccharides.

[0003] However, the current research and application of Suillus luteus polysaccharides still face many technical bottlenecks: first, the structural properties and biological functions of polysaccharides are highly dependent on the extraction conditions, and the existing common water-soluble alcohol extraction process often focuses on high molecular weight polysaccharide components, but ignores the mining of low molecular weight polysaccharides in alcohol-soluble components. Related studies have confirmed that low molecular weight polysaccharides have better water solubility and stronger cell permeability, and usually exhibit more excellent biological activity, and their development potential has not been fully released; second, as a macromolecular compound, polysaccharides are difficult to directly enter the body blood stream after oral administration, and their biological functions need to rely on the regulation of intestinal flora and their metabolites, but the interaction mechanism of Suillus luteus polysaccharides and intestinal flora, especially the specific action path of immune function mediated by key regulatory pathways of intestinal flora, has not formed a clear and systematic research conclusion, resulting in a lack of clear mechanism support in the development of immune regulation and anti-tumor related products, which restricts the process of technology transformation and industrialization application.

[0004] Therefore, developing a preparation process for Suillus luteus alcohol-soluble polysaccharides, clarifying its structural characteristics, and revealing its specific mechanism of enhancing immune function through intestinal flora metabolism, obtaining Suillus luteus polysaccharide raw materials with high biological activity, clear action target and industrial application potential, has become a key requirement to solve the current development bottleneck of Suillus luteus polysaccharides, promote the industrialization application of Suillus luteus polysaccharides in immune regulation and anti-tumor related products, and has important significance for promoting the efficient utilization of active ingredients of edible fungi and technological innovation in the field of biological medicine. SUMMARY

[0005] The present application provides a brown ring milk cow liver xylan palmitate (SLEP) and a preparation method and application thereof, the xylan palmitate prepared by the preparation method solves the technical bottlenecks of "unclear structure, low utilization rate of alcohol-soluble low molecular weight components and unclear mechanism" in the development of brown ring milk cow liver polysaccharide, provides a brown ring milk cow liver xylan palmitate with clear structural characteristics and high biological activity, and simultaneously discloses a preparation method, an immune improvement mechanism based on intestinal flora microecological regulation and an application direction, thereby providing high-quality active raw materials for the fields of functional food and biological medicine.

[0006] To achieve the above object, the present application provides the following technical scheme: a brown ring milk cow liver xylan palmitate, the brown ring milk cow liver xylan palmitate takes alpha-(1→4)-xylose as a main chain, alpha-(1→)-glucose as a branch, and forms a repeating unit through the main chain and the branch, and forms a xylan palmitate through an ester bond with a palmitic acid molecule.

[0007] Preferably, the main chain repeating unit of the brown ring milk cow liver xylan palmitate comprises nine xyloses, and the branch repeating unit of the brown ring milk cow liver xylan palmitate comprises two glucoses.

[0008] Preferably, the two glucoses of the branch repeating unit of the brown ring milk cow liver xylan palmitate are both connected to the third carbon of the xylose on the main chain.

[0009] Preferably, the ester bond is formed between the palmitic acid molecule and the terminal xylose on the main chain.

[0010] Preferably, the molecular weight of the brown ring milk cow liver xylan palmitate is (6.2±2)×10³ Da.

[0011] Preferably, the molar ratio of xylose:palmitic acid:glucose in the brown ring milk cow liver xylan palmitate is 1.00:0.03:0.28.

[0012] The present application also provides a preparation method of the brown ring milk cow liver xylan palmitate, and the preparation method comprises the following specific steps: S1, dry brown ring milk cow liver fruiting bodies are added to hot water at 70℃, soaked, concentrated by a rotary evaporator, and a brown ring milk cow liver concentrated solution is obtained.

[0013] S2, 4 times the volume of anhydrous ethanol is added to the brown ring milk cow liver concentrated solution obtained in step S1, uniformly mixed, and then left overnight, centrifuged, and the supernatant is collected, ethanol is removed, an appropriate amount of water is added for redissolution, and then frozen and dried to obtain the brown ring milk cow liver xylan palmitate.

[0014] Preferably, the material liquid ratio of the Suillus bovinus fruiting body in step S1 is 1:15-1:20 g / mL, the soaking time is 3-4 hours, the concentration temperature of the rotary evaporator is 55-60 DEG C, and the vacuum degree is 0.08-0.09 MPa; in step S2, the centrifugal speed is 4000 r / min, the centrifugal time is 15 min, and the ethanol in the supernatant is removed by rotary evaporation under the conditions of 45-50 DEG C and a vacuum degree of 0.08-0.09 MPa.

[0015] The application also provides a use of the Suillus bovinus xylan palmitate in preparation of a dietary supplement or a food additive for immunodeficient patients or tumor patients.

[0016] Compared with the prior art, the application has the following beneficial effects: 1. Structural innovation: the application first determines the structure of the Suillus bovinus-derived xylan palmitate, the main branch connection mode (alpha-(1→4)-xylose main chain, alpha-(1→)-glucose branch chain), and the esterification modification characteristics, thereby filling the blank of the structural study of the polysaccharide conjugate and providing a clear basis for the quality control and activity correlation; 2. Process superiority: the application provides an optimized and efficient preparation process, which can efficiently extract alcohol-soluble polysaccharide components, has stable product yield and high purity, does not require complex equipment, is suitable for industrial mass production, and solves the problem of waste of alcohol-soluble components in the traditional process; 3. Mechanism clarity: the application first discloses the action chain of "polysaccharide conjugate-intestinal flora quorum sensing-T cell immunity", determines that lactobacillus is the key flora and homoserine lactone is the core signal molecule, thereby providing clear scientific support for the application of the polysaccharide conjugate in the field of immune regulation and avoiding the disadvantages of "ambiguous action and uncontrollable effect"; 4. Wide application: the xylan palmitate has alcohol-soluble and water-soluble properties and low toxicity, can be applied in multiple fields such as "functional food-immune assistance-biopharmaceuticals", is suitable for immunocompromised people and tumor patients, has a broad market prospect, and promotes the transformation of Suillus bovinus from an edible resource to a high-value medicinal resource; Other features and advantages of the present application will become apparent from the following detailed description of exemplary embodiments thereof, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related art, the following will briefly introduce the drawings needed to be used in the embodiment or related art description. Obviously, the drawings in the following description are only embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of the provided drawings.

[0018] Figure 1 A high-performance gel permeation chromatogram of the brown ring lactarius xylanos palmityl ester of the present application; Figure 2 An infrared spectrum of the brown ring lactarius xylanos palmityl ester of the present application; Figure 3 A gas chromatography-mass spectrometry chromatogram of the brown ring lactarius xylanos palmityl ester of the present application; Figure 4 A 200x scanning electron microscope photograph of the brown ring lactarius xylanos palmityl ester of the present application; Figure 5 A nuclear magnetic resonance H spectrum of the brown ring lactarius xylanos palmityl ester of the present application; 1 Figure 6 A nuclear magnetic resonance C spectrum of the brown ring lactarius xylanos palmityl ester of the present application; 13 Figure 7 A nuclear magnetic resonance COSY spectrum of the brown ring lactarius xylanos palmityl ester of the present application; Figure 8 A nuclear magnetic resonance HSQC spectrum of the brown ring lactarius xylanos palmityl ester of the present application; Figure 9 A nuclear magnetic resonance HMBC spectrum of the brown ring lactarius xylanos palmityl ester of the present application; Figure 10 A structural formula of the brown ring lactarius xylanos palmityl ester of the present application; Figure 11 Another structural formula of the brown ring lactarius xylanos palmityl ester of the present application; Figure 12 A third structural formula of the brown ring lactarius xylanos palmityl ester of the present application; Figure 13 A graph showing the effects of the brown ring lactarius xylanos palmityl ester of the present application on the tumor weight and tumor inhibition rate of tumor-bearing mice; Figure 14 A Venn diagram showing the effects of the brown ring lactarius xylanos palmityl ester of the present application on the intestinal flora diversity of tumor-bearing mice; Figure 15 A ternary diagram showing the effects of the brown ring lactarius xylanos palmityl ester of the present application on the intestinal flora diversity of tumor-bearing mice; Figure 16 A significance analysis graph showing the effects of the brown ring lactarius xylanos palmityl ester of the present application on the intestinal lactobacillus of tumor-bearing mice; Figure 17 A heat map showing the effects of the brown ring lactarius xylanos palmityl ester of the present application on the intestinal flora metabolite content of tumor-bearing mice; Figure 18 ​​Volcano plot of the effect of brown ring milk cow liver xylan palmitate on the content of intestinal flora metabolites of tumor-bearing mice in the present application; Figure 19 KEGG enrichment bubble chart of the effect of brown ring milk cow liver xylan palmitate on intestinal flora metabolism of tumor-bearing mice in the present application; Figure 20 Figure of the effect of brown ring milk cow liver xylan palmitate on the distribution of peripheral blood T cell subsets of tumor-bearing mice in the present application; DETAILED DESCRIPTION

[0019] Please refer to Figures 1-20 The present application provides a technical solution: I. Structural characteristics of brown ring milk cow liver xylan palmitate: Brown ring milk cow liver xylan palmitate is a polysaccharide conjugate with alcohol and water solubility. Its core structural characteristics are analyzed by various detection methods, and the specific parameters are as follows: Chemical composition and proportion: Gas chromatography-mass spectrometry analysis shows that brown ring milk cow liver xylan palmitate is composed of xylose (Xylose, Xyl), palmitic acid (Palmitic acid, PA) and glucose (Glucose, Glc), and the molar ratio of the three is 1.00:0.03:0.28.

[0020] Molecular weight and physicochemical properties: Liquid exclusion chromatography detection shows that the average molecular weight of brown ring milk cow liver xylan palmitate is (6.2±2)×10³ Da, which belongs to low molecular weight polysaccharide conjugate; scanning electron microscopy observation shows that its microstructure is dense and easy to absorb water due to changes in environmental humidity.

[0021] Main branch structure and connection mode: Nuclear magnetic resonance analysis results show that brown ring milk cow liver xylan palmitate has α-(1→4)-xylose as the main skeleton (main chain), connects glucose as a branch chain through α-(1→) glycosidic bond, and forms a covalent bond with palmitic acid molecules through ester bond, forming a "polysaccharide-lipid" conjugate structure. This structure is the key basis for its alcohol and water solubility.

[0022] II. The preparation method of brown ring milk cow liver xylan palmitate is as follows: The present application optimizes the design of the preparation process for the extraction of brown ring milk cow liver alcohol-soluble polysaccharide conjugate, with clear steps and strong repeatability, suitable for industrial scale-up production, and the specific process is as follows: Raw material pretreatment: Select dry brown ring milk cow liver fruiting body without mold and impurities.

[0023] Hot water extraction and concentration: according to the ratio of 1:15-1:20 g / mL, the brown ring milk liver fungus is added into the 70℃ constant temperature water bath, soaked and stirred for 3-4h; after the end of extraction, the clear extraction liquid is collected; the extraction liquid is transferred into a rotary evaporator, concentrated under reduced pressure at 55-60℃, vacuum degree 0.08-0.09MPa, and the brown ring milk liver fungus concentrated liquid is obtained.

[0024] Alcohol soluble separation and purification: 4 times the volume of anhydrous ethanol is slowly added to the concentrated liquid (the volume fraction of ethanol in the system reaches 80%), and the ethanol is fully mixed by stirring; it is placed at room temperature overnight (12-16h) to make the non-alcohol soluble impurities fully precipitate; the next day, centrifugation is carried out at 4000r / min for 15 min, the bottom precipitate is discarded, and the alcohol soluble supernatant is collected; the supernatant is transferred into a rotary evaporator again, and the ethanol is evaporated at 45-50℃, vacuum degree 0.08-0.09MPa to obtain an alcohol-free concentrate; the alcohol-free concentrate is added with an appropriate amount of deionized water for redissolution, and the xylan palmitate aqueous solution is obtained by centrifugation.

[0025] Freeze-drying product: the pre-cooled sample is placed in a freeze dryer, and freeze-drying is carried out for 24-48h to obtain the xylan palmitate product of the brown ring milk liver fungus.

[0026] III. Mechanism of xylan palmitate of brown ring milk liver fungus in improving intestinal flora microecology of immune damage: The present application discloses the action path of xylan palmitate of brown ring milk liver fungus in regulating intestinal flora microecology, mediating quorum sensing system, and finally enhancing immune function through tumor-bearing mouse (immune damage model) animal experiment, and the specific experimental results are as follows: Experimental design and grouping: SPF Kunming mice (body weight 25±2g) are selected, adaptively fed for 1 week, and then randomly divided into 5 groups (10 in each group): blank control group (normal mice without immune damage), model control group (tumor-bearing model without intervention), positive control (CTX) group (tumor-bearing model + 30 mg / kg cyclophosphamide intraperitoneal injection), SLEP low dose group (tumor-bearing model + 100 mg / kg gavage), and SLEP high dose group (tumor-bearing model + 200 mg / kg gavage).

[0027] Intervention process: from the 1st to the 7th day, the low / high dose groups are gavaged with the corresponding concentration of SLEP solution every day, and the blank group and the model group are gavaged with the same volume of normal saline; on the 8th day, except for the blank group, the rest of the groups are subcutaneously injected with 2×10 6 S180 tumor cells in the right front limb to construct a tumor-bearing model; from the 9th to the 21st day, the blank group and the model group continue to be gavaged with normal saline, the CTX group is intraperitoneally injected with cyclophosphamide, and the low / high dose groups maintain the original dose gavage; after the end of the experiment, the tumor size, intestinal flora, and immune indicators are detected.

[0028] Modulation of intestinal flora diversity and structure: High-throughput sequencing analysis of the V3V4 region of the 16S rRNA gene showed that SLEP can restore the intestinal flora diversity of immune-damaged mice and significantly increase the abundance of Lactobacillus, confirming that the xylan palmitate can improve the imbalance of intestinal flora structure by enriching beneficial bacteria (Lactobacillus).

[0029] Mediation of the quorum sensing system of intestinal flora: Liquid chromatography-mass spectrometry (LC-MS) was used to detect the metabolic products of intestinal flora in mouse feces, and the results showed that SLEP can regulate cell communication between flora, inhibit the proliferation of harmful bacteria, and promote the function of beneficial bacteria.

[0030] Repair of immune damage and anti-tumor effect: Flow cytometry detection showed that SLEP gavage intervention can significantly increase the proportion of CD4 + T cells in peripheral blood of tumor-bearing mice, improve the immune damage state, and the tumor inhibition rate reaches 56.02%.

[0031] Four, application direction of xylan palmitate of X. subellipsoideus: Based on the above structural characteristics, preparation process and mechanism of action, the xylan palmitate of X. subellipsoideus of the present application can be applied in the following fields, and the specific scenarios are as follows: Functional food field: It can be used as a core functional ingredient to prepare dietary supplements or food additives for immunodeficient people, for example: added to probiotic milk powder (addition amount 0.5%-1.0%), through the synergistic effect of "polysaccharide conjugate + probiotic", the intestinal microecology of immunocompromised people such as the elderly and postoperative people is improved; or made into tablet candies (each tablet contains 100 mg of xylan palmitate), as a convenient food for daily immune regulation, suitable for long-term consumption.

[0032] Immune regulation field: It can be used as an immune auxiliary raw material for the auxiliary intervention of immunodeficient patients and tumor patients. For example, combined with tumor radiotherapy and chemotherapy adjuvant drugs, through the regulation of intestinal flora to reduce the intestinal mucosa damage caused by radiotherapy and chemotherapy, and at the same time enhance the immune activity of T cells and improve the treatment tolerance; or made into capsules alone for intestinal microecological repair of patients with chronic immunodeficiency diseases to reduce the recurrence rate of infection.

[0033] Biological medicine field: It can be used as a precursor of active pharmaceutical ingredients to further develop intestinal microecological regulation drugs. For example, for "intestinal flora imbalance related immune diseases" (such as inflammatory bowel disease combined with immunocompromised), it is made into enteric-coated tablets (to avoid damage by gastric acid) to achieve the dual treatment effect of "intestinal microecological repair-immune function enhancement" by targeting the regulation of intestinal lactobacillus and quorum sensing pathway. EMBODIMENT

[0034] The application will be further described in connection with the accompanying drawings and through specific embodiments, the following embodiments are only descriptive, not limiting, and cannot limit the protection scope of the application.

[0035] A preparation method of Suillus bovinus xylan palmitate, dry Suillus bovinus fruiting bodies without mildew and impurities are selected. The Suillus bovinus is added into a 70℃ constant temperature water bath at a ratio of 1:15 g / mL, soaked and stirred for 3h; after the extraction is completed, the clear extraction liquid is collected; the extraction liquid is transferred into a rotary evaporator for reduced pressure concentration, 4 times volume of anhydrous ethanol is slowly added into the concentrated liquid, and the room temperature is kept overnight, the next day, the upper alcohol-soluble supernatant is collected, and after the ethanol is removed, freeze-drying is carried out, and finally the Suillus bovinus xylan palmitate product (SLEP) is obtained.

[0036] The polysaccharide content of SLEP is detected by the phenol-sulfuric acid method, and the result is 86.35±4.36%.

[0037] The average molecular weight of SLEP is determined, and the result is shown in Figure 1 On the high-performance gel permeation chromatogram detected by liquid exclusion chromatography, a single, narrow and symmetrical peak appears, which proves that the molecular weight distribution of SLEP after purification is uniform, and the purity is high. The retention time 11.693 min is substituted into the standard curve (y = -0.4601x+9.1698, R2=0.9984, y represents the logarithmic value of the molecular weight, and x represents the corresponding retention time), and the average molecular weight of SLEP is about 6.2×10 3 Da.

[0038] The main characteristic functional groups of SLEP are determined, and the result is shown in Figure 2 The characteristic absorption peaks of polysaccharide are 3404.72 cm -1 , 2930.09 cm -1 and 1404.49 cm -1 , respectively, representing O-H stretching vibration, C-H stretching vibration and C-H deformation vibration of the compound. The strong absorption peak at 1632.82 cm -1 is attributed to the bending vibration absorption of O-H, and the absorption peak at 1000-1200 cm -1 is due to the existence of C-O-C glycosidic bond in polysaccharide. In addition, the absorption peak at 876.67 cm -1 indicates that the main α-type glycosidic bond connection mode exists in SLEP.

[0039] The monosaccharide composition of SLEP is determined, and the result is shown in Figure 3The substance identified by the peak with retention time of 9.0 min was xylose, 9.6 min was palmitic acid, and 9.7 min was glucose, and the molar ratio of the three components of xylose, palmitic acid and glucose in SLEP was 1.00:0.03:0.28 according to their relative contents.

[0040] Figure 4 The microstructure of SLEP is shown at 200 times magnification. SLEP presents a dense, irregular agglomerate structure, with wrinkles on the surface, and is easy to absorb water and get wet, which may be closely related to its structural composition and physicochemical properties.

[0041] Figure 5 The SLEP is 1 H spectrum. The chemical shift at 4.79 ppm can be attributed to the presence of proton signal of D2O. The signal range of 5.20 ppm indicates that SLEP mainly contains anomeric hydrogen signals of α-type glycosidic bond, and the signal value of 6.53 ppm indicates that it contains ester bonds formed by fatty acid compounds and hydroxyl groups, and the signal peak value of 3.0-4.5 ppm indicates the presence of H2-H6 in these sugar residues.

[0042] Figure 6 The SLEP is 13 C spectrum. Combined with the above results, the anomeric carbon signal of fatty acid is observed at about 135.33, and the anomeric carbon signal of α-type glycosidic bond is found at 93.20 ppm, and the signals of C2-C6 in the conjugate residue are mainly distributed between 53.85 ppm and 72.49 ppm.

[0043] Figure 7 The correlation of the adjacent hydrogen atoms in SLEP is shown, and the relevant cross- absorption signals are labeled. Among them, A represents α-Xylp, and B represents α-Glcp. The first digit represents the horizontal coordinate, and the second digit represents the vertical coordinate.

[0044] Figure 8 The chemical shifts of the carbon hydrogens of the first to sixth carbon atoms of the xylose and glucose residues in the SLEP sugar residues are analyzed.

[0045] Figure 9 The presence of A1,4 and A3B1 carbon hydrogen cross signals is identified in the SLEP, and the results show that the xylan palmitate of X. badius mainly consists of α-(1→4)-Xylp and α-(1→)-Glcp, and α-(1→)-Glcp links the third carbon atom of the main chain xylose as a branch.

[0046] As Figure 10 , Figure 11 and Figure 12The structure of SLEP was speculated according to the above results. SLEP has an α-(1→4)-Xylp backbone, and α-(1→)-Glcp branches from the third carbon atom of the backbone xylose, and covalently links a palmitic acid molecule. Among them, the connection of two glucose molecules in the repeating unit with xylose has multiple possibilities, such as Figure 10 Two glucose molecules are connected to the 3rd and 6th xylose, as shown in Figure 11 Two glucose molecules are connected to the 2nd and 8th xylose, as shown in Figure 12 Two glucose molecules are connected to the 4th and 5th xylose. In addition to the above three possibilities, there are also various arbitrary combination cases.

[0047] Figure 13 The tumor weight and inhibition rate of tumor-bearing mice after different treatments are shown. The results show that the tumor weight of mice in the cyclophosphamide group and the Inonotus bresadolan xylan palmitate group is significantly reduced compared with the model group, and the tumor inhibition rates are 57.37%, 38.83% and 56.35%, respectively. Cyclophosphamide is a common chemotherapeutic drug that can indiscriminately eliminate immune cells and tumor cells, and has a certain positive effect on the inhibition of transplanted tumor growth, but the immune capacity of the body is also damaged. SLEP can effectively improve the anti-tumor immune capacity of the body.

[0048] As shown in Figure 14 Each circle represents a group, and the number of overlapping (non-overlapping) ellipses represents the number of shared (unique) OTUs. As mentioned above, the four experimental groups have a total of 507 OTUs, while the unique OTUs of the blank group, model group, CTX group and SLEP high dose group are 103, 135, 98 and 80, respectively, indicating that these experimental groups exhibit extensive intestinal microbial community diversity, which may be the reason for the difference in anti-tumor immune capacity of different groups.

[0049] Figure 15 The ternary phase diagram of the top 10 intestinal microbial genera is shown. Compared with the model group, the abundance of Lactobacillus in the blank group and the SLEP group is significantly increased, indicating that it is closely related to the progression of solid tumors in mice, which may be the main reason for the enhanced anti-tumor immunity of tumor-bearing mice after SLEP intervention.

[0050] Figure 16 The abundance of intestinal Lactobacillus in the SLEP group is significantly higher than that in the model group (p<0.05), which is consistent with the previous research results, indicating that Lactobacillus is a key intestinal flora for SLEP to regulate the immune capacity of tumor-bearing mice.

[0051] Non-targeted metabolomics was used to detect metabolites with significant differences between the model group and the SLEP high dose group, and the results are shown in Figure 17The color from blue to red represents the relative content of metabolites, and the horizontal direction represents sample information (3 parallel samples). There are 43 metabolites in the SLEP high-dose group that are significantly different from the model group (p<0.05), of which 15 are down-regulated and 28 are up-regulated. However, the function of these metabolites in tumor-bearing mice needs further analysis.

[0052] In Figure 18 the volcano plot, each point represents a metabolite, and metabolites that are significantly up-regulated (down-regulated) compared with the model group are represented by red dots (blue dots), while metabolites with no significant difference are represented by gray, which is consistent with Figure 17 .

[0053] The differential metabolites in the positive and negative ion modes obtained by statistical analysis were enriched by KEGG database for pathway analysis, as shown in Figure 19 . Each bubble represents a metabolic pathway, and the difference in metabolites may be related to changes in cellular pathways. Compared with the model group, the most significant signal pathway affected by the SLEP high-dose group on the intestinal tract metabolism is quorum sensing. Quorum sensing (QS) refers to a sensing phenomenon that occurs only when the number of bacteria reaches a certain density, and as a mode of intercellular communication that changes microbial interactions, it can regulate the formation of biofilms, the secretion of public goods, and the synthesis of antibacterial substances, directly or indirectly affecting the adaptation of microbial communities. This indicates that SLEP exerts an immune-enhancing effect by affecting the quorum sensing system of intestinal flora, ultimately inhibiting the growth of solid tumors in the body.

[0054] Figure 20 The proportion of peripheral blood CD4 + and CD8 + T cells in blank group, model group, CTX group, and SLEP high-dose group mice is shown. The results show that compared with the blank group, the proportion of CD4 + cells in the model group is significantly reduced (p<0.05), while the proportion of CD4 + T cells in the SLEP group is significantly higher than that in the model group (p<0.05), indicating that SLEP may have a stronger immune regulatory effect on CD4 cells. The proportion of CD8 + T cells in each group is relatively stable, but compared with the model group, the proportion of CD8 + T cells in the CTX group and the SLEP group is significantly reduced (p<0.05). Combined with the previous results, it can be inferred that CTX has shown activity inhibition on both T cell subpopulations, while SLEP enhances the activity of CD4 + T cells to activate and recruit CD8 + T cells to exert direct killing effect on tumor cells.

[0055] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application, which is not limited to the exact construction and arrangement described. It is intended, therefore, to cover all modifications and adaptions that fall within the scope of the claims and their equivalents.

Claims

1. A Suillus suillus xylan palmitate, characterized in that: The Suillus fusca xylan palmitate has α-(1→4)-xylose as a main chain and α-(1→)-glucose as a side chain, and the main chain and the side chain form a repeating unit. The xylan palmitate is formed by an ester bond with a palmitic acid molecule.

2. The Suillus suillus xylan palmitate according to claim 1, characterized in that: The main chain repeating unit of the Suillus suillus xylan palmitate includes nine xyloses, and the side chain repeating unit of the Suillus suillus xylan palmitate includes two glucoses.

3. The Suillus suillus xylan palmitate according to claim 2, characterized in that: The two glucoses in the Suillus suillus xylan palmitate branched repeating unit are both connected to the third carbon of the xylose on the main chain.

4. The Suillus suillus xylan palmitate according to claim 1, characterized in that: The ester bond is formed between the palmitic acid molecule and the terminal xylose on the main chain.

5. The Suillus suillus xylan palmitate according to claim 1, characterized in that: The molecular weight of the Suillus suillus xylan palmitate is (6.2±2)×10³Da.

6. The Suillus suillus xylan palmitate according to claim 1, characterized in that: The molar ratio of xylose:palmitic acid:glucose in the Suillus fusca xylan palmitate is 1.00:0.03:0.

28.

7. The method for preparing Suillus suillus xylan palmitate according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following specific steps: S1, adding the dried fruiting bodies of Suillus edulis into hot water at 70° C., soaking, and concentrating using a rotary evaporator to obtain a Suillus edulis concentrate; S2, adding 4 times the volume of anhydrous ethanol to the concentrated solution of Suillus edulis obtained in step S1, mixing and standing overnight, centrifuging, collecting the supernatant, removing ethanol, adding appropriate amount of water for re-dissolution, and freeze-drying to obtain Suillus edulis xylan palmitate.

8. The method for preparing Suillus suillus xylan palmitate according to claim 7, characterized in that: In step S1, the brown-ringed boletus fruiting body is soaked in hot water at a material-liquid ratio of 1:15-1:20 g / mL, and the soaking is carried out for 3-4 hours. The concentration temperature of the rotary evaporator is 55-60° C. and the vacuum degree is 0.08-0.09 MPa. In step S2, the centrifugation is performed at a speed of 4000 r / min for 15 minutes, and the supernatant is subjected to a method for removing ethanol by rotary evaporation under conditions of 45-50° C. and a vacuum degree of 0.08-0.09 MPa.

9. Use of the Suillus suillus xylan palmitate according to any one of claims 1 to 4 in preparing a dietary supplement or food additive for immunodeficiency patients or tumor patients.

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