Polysaccharide from boletus edulis fruiting body, and preparation method and application thereof

Abstract

The present application belongs to the technical field of application of fungal polysaccharides, and particularly relates to a Boletus edulis fruiting body polysaccharide as well as a preparation method and application thereof. Polysaccharides in Boletus edulis fruiting bodies are extracted, and the chemical structure of BDP-F is characterized by ultraviolet-visible light, Fourier transform infrared spectroscopy, one-dimensional nuclear magnetic resonance and two-dimensional nuclear magnetic resonance. The research results show that BDP-F is mainly composed of mannose, glucose, galactose and fucose. Methylation and nuclear magnetic resonance analysis show that the glycosidic bond of BDP-F is (1→6)-alpha-d-galactose, the main chain is composed of ->6)-alpha-d-galp-(1→ residues, and the O-2 position is branched by alpha-L-Fucp-(1→ and alpha-D-Manp-(1→ residues. Through DPPH free radical, hydroxyl radical and superoxide anion radical scavenging experiments, it is shown that BDP-F has the ability to serve as a natural antioxidant, and BDP-F can also reduce alcohol-induced GES-1 cell damage through antioxidant and anti-inflammatory effects within the experimental concentration range.

Description

Technical Field

[0001] This invention belongs to the field of fungal polysaccharide application technology, specifically relating to a polysaccharide from the fruiting body of Boletus edulis, its preparation method, and its application. Background Technology

[0002] Gastric mucosal injury is a common pathological basis for digestive system diseases, which can be induced by various factors such as nonsteroidal anti-inflammatory drugs (NSAIDs), alcohol, and Helicobacter pylori infection. Its core mechanisms involve oxidative stress, release of inflammatory factors, and disruption of the mucosal barrier. While traditional drugs (such as proton pump inhibitors) can relieve symptoms, long-term use may cause side effects (such as osteoporosis and gut microbiota dysbiosis). In recent years, natural active polysaccharides have become a research hotspot in the development of gastric mucosal protectants due to their multi-target regulatory properties (antioxidant, anti-inflammatory, and repair-promoting) and low toxicity. *Boletus bainiugan* Dentinger is a bolete abundant in the wild and widely consumed. However, current research on the active components of *Boletus bainiugan* is relatively scarce, especially regarding the fine structure, structure-activity relationship, and repair effects of its polysaccharide components on gastric mucosal injury. Summary of the Invention

[0003] Based on the above problems, the first technical solution of this application provides a polysaccharide from the fruiting body of Boletus edulis, the main chain structure of which is as follows:

[0004] ;

[0005] The polysaccharide from the fruiting body of *Boletus edulis* contains 21%–25% fucose and mannose side chains, and 20%–23% α-1,4-glucan and β-1,6-glucan branched fragments; among which, the structural fragments of α-1,4-glucan and β-1,6-glucan are as follows:

[0006] ;

[0007] .

[0008] The second technical solution of this application discloses a method for preparing the polysaccharide from the fruiting body of Boletus edulis, comprising the following steps:

[0009] S1. The fruiting bodies of Boletus edulis were crushed, defatted, extracted with distilled water, concentrated, decolorized, eluted, and freeze-dried to obtain crude polysaccharide BDP;

[0010] S2. BDP was separated and purified by chromatography using distilled water as the eluent to obtain the polysaccharide BDP-F from the fruiting body of Boletus edulis;

[0011] And the white boletus fruiting body polysaccharide obtained by the above preparation method.

[0012] The third technical solution of this application discloses the application of the above-mentioned Boletus edulis fruiting body polysaccharide in the preparation of antioxidant drugs or in the preparation of drugs for repairing or protecting gastric mucosal damage.

[0013] Compared with existing technologies, this invention has the following beneficial effects: The polysaccharide BDP-F was extracted from the fruiting body of *Boletus edulis* and its chemical structure was characterized by ultraviolet-visible light, Fourier transform infrared spectroscopy, one-dimensional nuclear magnetic resonance (NMR), and two-dimensional NMR. The results showed that BDP-F is mainly composed of mannose, glucose, galactose, and fucose. Methylation and NMR analyses indicated that the glycosidic bonds of BDP-F consist of (1→6)-α-d-galactan, the main chain is composed of (1→6)-α-d-galp-(1→) residues, and the O-2 position is branched by α-L-Fucp-(1→) and α-D-Manp-(1→) residues. Scavenging experiments with DPPH radicals, hydroxyl radicals, and superoxide anion radicals showed that BDP-F has the ability to act as a natural antioxidant, and within the experimental concentration range, BDP-F can also alleviate alcoholic GES-1 cell damage through antioxidant and anti-inflammatory effects. Attached Figure Description

[0014] Figure 1 The results of the separation and purification of BDP are shown in the figure, where (A) is the elution curve of BDP on the DEAE-52 column; (B) is the HPGPC chromatogram.

[0015] Figure 2 The results of the structural characterization study of BDP-F are shown in (A) for ultraviolet spectrum, (B) for infrared spectrum, (C) for monosaccharide composition analysis of standard sample and BDP-F, and (D) for methylation analysis results of BDP-F.

[0016] Figure 3 The results are from BDP-F nuclear magnetic resonance analysis, where... Figure 3 A is 1 H NMR analysis results, Figure 3 B is 13 C NMR analysis results, Figure 3 C represents the isomer region in HSQC. Figure 3 D represents the COSY analysis result. Figure 3 E represents the isomer region in HMBC. Figure 3 F represents the NOESY analysis result;

[0017] Figure 4 This is a presumed structural diagram of BDP-F;

[0018] Figure 5 The image shows the results of the BDP-F antioxidant experiment. Figure 5A represents the results of the DPPH scavenging experiment. Figure 5 B represents the results of the hydroxyl radical scavenging experiment. Figure 5 C represents the results of the superoxide anion scavenging experiment;

[0019] Figure 6 The results are from the BDP-F cytotoxicity assay.

[0020] Figure 7 The effect of ethanol on the survival rate of GES-1 cells;

[0021] Figure 8 Figure 1 shows the experimental results of the preventive effect of BDP-F on EtOH-induced GES-1 cell damage. (A)-(C) represent the antioxidant level of GES-1 cells exposed to BDP-F; (D)-(E) represent the anti-inflammatory level of GES-1 cells exposed to BDP-F. Data are expressed as mean ± SD (n = 6). Compared with the control group: # p < 0.05, ## p < 0.01; compared with the model group: * p < 0.05; ** p < 0.01. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0024] Unless otherwise specified, the technical terms in this specification have the same meaning as those generally understood by those skilled in the art; however, in case of any conflict, the definitions in this specification shall prevail.

[0025] The first embodiment of this application discloses a polysaccharide from the fruiting body of Boletus edulis, the main chain structure of which is as follows:

[0026] ;

[0027] The polysaccharide from the fruiting body of *Boletus edulis* contains 21%–25% fucose and mannose side chains, and 20%–23% α-1,4-glucan and β-1,6-glucan branched fragments; among which, the structural fragments of α-1,4-glucan and β-1,6-glucan are as follows:

[0028] ,

[0029]

[0030] The polysaccharide from the fruiting body of Boletus edulis was prepared by the following method.

[0031] S1. 200 g of dried Boletus edulis fruiting bodies were pulverized and passed through a 40-mesh sieve (0.3 mm pore size) to collect the fine powder. Subsequently, 95% ethanol was added at a material-to-liquid ratio of 1:4 (m / v) for defatting for 30 min. After defatting, the powder was mixed with distilled water at a ratio of 1:20 (m / v) and extracted three times at 80 °C for 80 min each time. All extracts were combined and concentrated under reduced pressure using a rotary evaporator at 60 °C. The precipitate was collected and freeze-dried. The obtained polysaccharide was redissolved, and HPD-100 macroporous resin (50% by volume of liquid) was added. The mixture was decolorized by shaking at 75 °C for 6 h. The eluent after decolorization was further adsorbed with 12% polyamide powder for 4 h. After elution, the eluent was collected and freeze-dried to obtain the crude polysaccharide product (BDP).

[0032] S2. 1 g of BDP sample was dissolved in distilled water and loaded onto a equilibrated DEAE-52 cellulose column, followed by gradient elution at a flow rate of 1 mL / min. The elution program consisted of distilled water and NaCl solutions at concentrations of 0.1, 0.2, 0.4, 0.8, and 1.0 M. The total sugar content of each fraction was monitored using the phenol-sulfuric acid method, and the distilled water eluent fraction with the highest polysaccharide content was collected and further purified using a Chromdex 75PG column. The obtained fraction was named BDP-F. BDP-F was subsequently selected for structural characterization and cell experiments in this study.

[0033] After decolorization, deproteinization, and ethanol precipitation, the yield of crude polysaccharide (BDP) from *Boletus edulis* was 16.8%. Its DEAE-52 cellulose column elution curve (using distilled water and NaCl solutions of different concentrations for stepwise elution) is shown below. Figure 1As shown in Figure A, analysis revealed that the distilled water eluent was the main component, with the highest polysaccharide content and a yield of 30 ± 9.08%. Therefore, this water-eluted fraction was selected for further purification using a Sephadex G-75 gel column to obtain fraction BDP-F (…). Figure 1 B). The above results determined the optimal preparation process for the polysaccharide from the fruiting body of Boletus edulis and successfully obtained its main component, BDP-F. Subsequent experiments all used this purified BDP-F as the research object.

[0034] Example 1: Structural Characteristics Study of BDP-F

[0035] 1. Determination of BDP-F molecular weight

[0036] Accurately weigh dextran standards of different molecular weights (1000, 5000, 12000, 25000, 50000, 80000, 150000, 270000, 410000, and 670000 Da), dissolve and dilute to volume with 0.05 M NaCl solution to prepare standard solutions with a concentration of 5 mg / mL. Filter the solutions through a 0.22 μm microporous membrane for later use. High-performance gel permeation chromatography (HPLC) was used for analysis. The system consisted of an HPLC instrument, a differential detector, and OHpak SB-803HQ, SB-804 HQ, and SB-805 HQ columns (8 × 300 mm) connected in series. The mobile phase was 0.05 M NaCl solution, the flow rate was set to 0.65 mL / min, the column temperature was 40 °C, and the injection volume was 30 μL.

[0037] HPGPC analysis results (Table 1) show that the peak area ratio of this polysaccharide component exceeds 92.16%, indicating high purity and uniform composition. The polydispersity index is 1.4, indicating a narrow molecular weight distribution.

[0038] Table 1 Molecular characteristics of BDP-F

[0039] .

[0040] 2. Monosaccharide composition analysis

[0041] (1) A UV-Vis spectrophotometer (JASCO, Japan) was used to scan a 1 mg / mL BDP-F polysaccharide solution in the wavelength range of 200-400 nm. 2 mg of BDP-F sample was weighed and mixed with 200 mg of dried KBr powder, then thoroughly ground and compressed into tablets. Subsequently, a Fourier transform infrared spectrometer (Thermo Scientific, USA) was used to scan the sample in the wavelength range of 4000-400 nm. −1 Its infrared spectrum was collected within the range.

[0042] (2) Analysis of the monosaccharide composition of BDP-F using high-performance anion exchange chromatography: Approximately 5 mg of BDP-F sample was accurately weighed into a sealed hydrolysis tube, 2 M trifluoroacetic acid was added, and hydrolysis was carried out at 121 °C for 2 h. After cooling, the hydrolysate was dried under a nitrogen stream to completely remove TFA. Methanol was added to the residue, vortexed to disperse, and then dried again. This step was repeated 2-3 times. Finally, the residue was reconstituted with deionized water, filtered through a 0.22 μm aqueous filter membrane, and analyzed using a Thermo U3000 ion chromatography system (Thermo Fisher Scientific, USA). The system was equipped with a CarboPac PA20 anion exchange column. The retention time of each monosaccharide was determined by analyzing the mixed monosaccharide standard solution.

[0043] (3) Take 3 mg of dried BDP-F sample and dissolve it in 500 μL of dimethyl sulfoxide (DMSO); mix the polysaccharide solution with 500 μL of dichloromethane (CH2Cl2), add 1 mL of distilled water, vortex thoroughly, centrifuge, and discard the aqueous phase. Repeat this washing step several times with distilled water to purify the methylated polysaccharide. Hydrolyze the purified methylated polysaccharide with 2 M trifluoroacetic acid (TFA) at 120 °C for 90 min. After reduction with sodium deuterated borohydride (NaBD4) and acetylation with acetic anhydride, the hydrolysate was analyzed using a 7890A-5977B gas chromatography-mass spectrometry (GC-MS) system equipped with an HP-5MS capillary column (Agilent Technologies, USA). The GC temperature program was: initial temperature 140 °C, hold for 2 min; increase to 230 °C at a rate of 3 °C / min, hold for 3 min. The mass spectrometer was used in SCAN mode, and the mass-to-charge ratio (m / z) ranged from 30 to 600.

[0044] Experimental results are as follows Figure 2 (The results of the structural characteristics study of BDP-F are shown below): Figure 2 A is the UV-Vis spectrum of BDP-F, showing no obvious absorption peaks at 260 nm and 280 nm, indicating that no nucleic acids and proteins were detected at this detection limit, proving that the BDP-F sample has high purity.

[0045] Figure 2 B represents BDP-F infrared spectroscopy analysis, indicating that the polysaccharide sample possesses a characteristic absorption peak for polysaccharides: 3412.45 cm⁻¹. -1 A strong and broad absorption peak exists at 2924.43 cm⁻¹, which is the strong absorption peak of the OH stretching vibration of hydrogen bonds between or within polysaccharide molecules; -1 The nearby moderate-intensity spikes are absorption peaks of the CH stretching vibrations of methyl (-CH3) and methine (-CH2) groups; 1648.30 cm⁻¹ -1The absorption peak at [value missing] cm⁻¹ is attributed to the C=O stretching vibration of the carbonyl group or the formation of water of crystallization in the sugar; within the range of 1450-1200 cm⁻¹, the absorption peaks at 1409.76 cm⁻¹ and 1354.56 cm⁻¹ can be attributed to the bending vibration of CH; the absorption peak at 1247.19 cm⁻¹ may originate from the bending vibration of COH or the vibration of the sugar ring skeleton; the absorption peak at 1150.56 cm⁻¹... -1 The stretching vibration of pyranose COC; 1150-1010 cm -1 The two strong absorption peaks between, at 1077.40 cm⁻¹ -1 1038.48 cm -1 The presence of pyranoside was further confirmed at these two sites, and the absorption at both sites was due to the bending vibration of the CO bond in the COH or COC structure; 972.37 cm⁻¹ -1 The peak indicates a vibrational peak in carbohydrate molecules, at 918.70 cm⁻¹. -1 The peak at 872.85 cm⁻¹ shows the asymmetric ring stretching vibration of the pyran ring. -1 This is a characteristic region of a β-pyranoside bond, suggesting the presence of β-pyranose in the polysaccharide; 819.14 cm -1 The peak represents the CH-angle vibration of the α-terminal epimer of pyranose; 766.40 cm⁻¹ -1 The peaks of symmetrical ring stretching vibrations of the pyran ring are shown.

[0046] Figure 2 C shows the monosaccharide composition analysis of the standard sample and BDP-F. Combined with Table 2 (monosaccharide composition of BDP-F), it can be seen that BDP-F is a heteropolysaccharide, with its main monosaccharide components being galactose (52.58%), glucose (21.97%), and fucose (14.80%), and containing small amounts of mannose (9.70%), glucosamine (0.61%), and glucuronic acid (0.34%). This compositional characteristic suggests that BDP-F may have a branched structure dominated by galactose, and the presence of some acidic groups (such as glucuronic acid) may help enhance its hydrophilicity and biological activity.

[0047] Table 2 Monosaccharide composition of BDP-F

[0048] .

[0049] Figure 2Figure D shows the methylation analysis results of BDP-F. Combined with Table 3 (Methylation Analysis of BDP-F), the methylation analysis of BDP-F reveals a complex structure composed of 16 glycosidic bond types. The main bond types include 1,6-Galp (31.57%), 1,2,6-Galp (19.93%), 1,4-Glcp (12.72%), and t-Fucp (12.02%). Residue analysis shows that Gal and Glc account for 54.04% and 26.68% respectively, consistent with the monosaccharide composition results. Terminal residues account for 22.39% of the total residues, indicating a highly branched structure in the polysaccharide. Notably, the terminal residue t-Fucp (12.02%) is a characteristic structure and may be involved in activating the TLR4 / NF-κB signaling pathway.

[0050] Table 3. Methylation analysis of BDP-F

[0051]

[0052] From the perspective of the main chain structure, 1,4-glcp (12.72%) and 1,6-galp (31.57%) are the major bonds, indicating that these residues may constitute the main chain. Furthermore, 1,6-glcp (5.40%) and 1,3-glcp (1.94%) may be located in specific segments of the main chain or serve as branching points. Residues involved in branching include 1,4,6-glcp, 1,2,6-manp, and 1,2,6-galp, which together account for 25.03% of the total content, indicating a high degree of branching of Gal residues, particularly at the O-2 and O-6 positions.

[0053] 3. Nuclear magnetic resonance analysis

[0054] The dried BDP-F sample was dissolved in deuterated water (D2O) to prepare a solution with a concentration of 40 mg / mL, and then loaded into NMR tubes. All NMR spectra, namely one-dimensional ¹H NMR, ¹³C NMR and two-dimensional COSY, NOESY, HSQC, and HMBC spectra, were acquired at 25 °C on a Bruker AVANCE HD III 600 MHz NMR spectrometer (Bruker GmbH, Germany).

[0055] like Figure 3 The results of BDP-F nuclear magnetic resonance analysis are shown below. Figure 3 A is 1 H NMR analysis results, Figure 3 B is 13 CNMR analysis results Figure 3 C represents the isomer region in HSQC. Figure 3 D represents the COSY analysis result. Figure 3E represents the isomer region in HMBC. Figure 3 F represents the NOESY analysis results, in conjunction with Table 4. 1 H and 13 The chemical shift of the BDP-F resonance in the C NMR spectrum indicates that:

[0056] One-dimensional nuclear magnetic resonance hydrogen spectroscopy (NMR) was used 1 Further analysis using 1H-NMR revealed the glycosidic bond configuration of the polysaccharide samples. The 1H NMR signals of the polysaccharides were mostly in the δ 3.0–5.5 ppm range, with the anomeric proton (H-1) resonance region typically between δ 4.3–5.5 ppm. The polysaccharide samples… 1 H-NMR spectrum ( Figure 3 A) A large number of proton resonance signals are concentrated in the δ 3.0–5.5 ppm region, with severe signal overlap. Multiple anodic hydrogen signals were found in the anodic region (δ 4.3–5.5 ppm), indicating the presence of various sugar residues, and these signals also overlapped to some extent, making them difficult to distinguish. Other hydrogen signals were concentrated in the δ 4.3–3.0 ppm region, with significant signal overlap, making them difficult to assign. 1 Compared to H-NMR spectra, polysaccharide samples 13 C-NMR spectrum ( Figure 3 B), with fewer spectral lines and multiple anomeric carbons in the δ 90–110 ppm anomeric carbon region, indicates the presence of various sugar residues. From 1 H-NMR and 13 On the C-NMR spectrum, some characteristic signal peaks were found: (1) The resonance signal located near δ 1.12 ppm in the high field is the chemical shift of the methyl proton H-6 of the typical 6-position deoxy sugar. The special deoxy structure of the methyl carbon C-6 is near δ 15.60 ppm. In the HSQC spectrum ( Figure 3 (C) A cross peak of δ 1.12 / 15.60 ppm was found on the carbon spectrum. Based on the monosaccharide composition results, it was inferred that it was the chemical shift of H-6 and C-6 of fucose; (2) δ 56.00 ppm on the carbon spectrum is the carbon atom signal of methoxy group formed by the substitution of hydrogen atom in hydroxyl group. A cross peak of δ 3.34 / 56.00 pp was found on the HSQC spectrum. The peak signal intensity is very small. Based on this, it can be inferred that there is a low degree of methoxy substitution in this polysaccharide sample; (3) Reduced end groups appeared at δ 91.84 ppm and δ 95.68 ppm. Two signal cross peaks of δ 5.11 / 91.84 ppm and δ 4.53 / 95.68 ppm were found in the anodic region of the HSQC spectrum. Then, through the COSY spectrum ( Figure 3D) The cross peaks δ 5.11 / 3.41 ppm and δ 4.53 / 3.13 ppm suggest that the signal H-2 chemical shifts of these two sugar residues are δ 3.41 ppm and δ 3.13 ppm, respectively. Based on the monosaccharide composition determination and methylation analysis results, combined with literature reports, it is inferred that these peaks belong to the reducing end groups α-Glcp and β-Glcp, and are labeled as R... α and R β By using the cross peaks in the HSQC spectrum, R was obtained. α and R β The C-2 chemical shifts were δ 72.25 ppm and δ 73.87 ppm, respectively. Since these two peaks were relatively weak, they could not be fully assigned. Based on comparison with literature data and methylation results, the sugar residue R was inferred to be... α For →4)-α-D-Glcp, R β →4)-β-D-Glcp.

[0057] In the monosaccharide composition test and methylation analysis results, the main monosaccharide components were Gal (52.583%), Glc (21.971%), Fuc (14.798%), and Man (9.704%). The methylation analysis results showed that the main methylation compounds included 1,6-Galp, 1,2,6-Galp, 1,4-Glcp, 1,4,6-Glcp, 1,6-Glcp, 1,3,6-Glcp, t-Glcp, t-Manp, and t-Fucp. 1 H-NMR, 13 C-NMR, HSQC, and COSY NMR spectra revealed multiple anodic signals. Combined with literature reports, the presence of multiple anodic signal cross-peaks in the HSQC spectrum of polysaccharide samples is significant and can be used for structural analysis.

[0058] Two strong cross-peak signals, δ 4.87 / 97.75 ppm (H-1 / C-1) and δ 4.95 / 97.94 ppm (H-1 / C-1), were observed near the anodic region in the HSQC spectrum (δ 4.83–4.98 ppm and δ 96–99 ppm, respectively). Cross-peak signals of anodic hydrogens in this region were also found in the COSY spectrum (δ 4.87 / 3.72 ppm (H-1 / H-2) and δ 4.95 / 3.70 ppm (H-1 / H-2). Based on methylation analysis results and literature reports, these signals are presumably mainly from the anodic signal of the sugar residue α-Galp. The H-1 chemical shift of the sugar residue was determined to be δ 4.87 using HSQC and COSY. The chemical shifts of the H-2, H-3, H-4, and H-5 residues can be derived from the cross-peaks in the COSY spectrum. These shifts are assigned to δ 3.72 ppm, δ 3.77 ppm, δ 3.90 ppm, and δ 4.09 ppm, respectively. The H-6a and H-6b shifts can be assigned using the HSQC spectrum, with values ​​of δ 3.56 ppm and δ 3.80 ppm, respectively. After assigning the chemical shifts of the hydrogen atoms on the sugar ring, the chemical shifts of C-1 to C-6 on the sugar ring can be assigned using the HSQC correlation spectrum, with values ​​of δ 97.75 ppm, δ 68.08 ppm, δ 69.36 ppm, δ 69.35 ppm, δ 68.57 ppm, and δ 66.40 ppm, respectively. The chemical shifts of C-1 and C-6 towards a lower field indicate that these residues have undergone substitution at positions C-1 and C-6 of the sugar ring. Based on literature reports, it is inferred that the sugar residue is →6)-α-D-Galp-(1→, labeled as Gal 1,6 The chemical shifts are assigned in Table 1. Following a similar method, the chemical shifts of the sugar residues at 4.97 / 97.96 ppm (H-1 / C-1) of the anodic signal were deduced using HSQC and COSY, and their assignments are shown in Table 4. The chemical shifts of C-1, C-2, and C-6 shift towards the lower field, indicating that these residues have undergone substitution at positions C-1, C-2, and C-6 of the sugar ring. Based on the methylation analysis results and literature reports, the sugar residue is inferred to be →2,6)-α-D-Galp-(1→, labeled as Gal... 1,2,6 .

[0059] Two cross-peak signals, δ 4.93–5.01 ppm in the proton NMR spectrum and δ 100–102 ppm in the carbon NMR spectrum, were observed near the anterior region: δ 4.96 / 101.34 ppm (H⁻¹ / C⁻¹) and δ 5.00 / 102.09 ppm (H⁻¹ / C⁻¹). Cross-peak signals, δ 4.93 / 3.67 ppm (H⁻¹ / H⁻²) and δ 5.00 / 4.08 ppm (H⁻¹ / H⁻²), were found in the COSY spectrum for the anterior hydrogens in this region. Based on comparison with literature data and methylation results, the corresponding sugar residues were inferred to belong to α-L-Fucp-(1→) and α-D-Manp-(1→), respectively, and labeled as F… t and M t The chemical shifts were derived using HSQC and COSY, and their assignments are shown in Table 4.

[0060] A cross-peak signal was observed near the 5.20–5.30 ppm ¹H NMR and 99–100 ppm ¹³C NMR regions in the HSQC anodic region. Cross-peak signals were also found in the COSY spectrum at 5.27 / 3.47 ppm (H⁻¹ / H⁻²) and 5.23 / 3.46 ppm (H⁻¹ / H⁻²) anodic hydrogens in this region. Based on methylation analysis results and literature reports, these signals are presumably mainly from the α-Glcp sugar residue. The HSQC spectrum showed α-Glcp sugar residue anodic signals at 5.27 / 99.55 ppm (H⁻¹ / C⁻¹) and 5.23 / 99.87 ppm (H⁻¹ / C⁻¹). The H⁻¹ chemical shift of the sugar residue was determined to be δ 5.27 using both HSQC and COSY. The chemical shifts of the H-2, H-3, H-4, and H-5 residues can be derived from the cross-peaks in the COSY spectrum. These shifts are assigned to δ 3.47 ppm, δ 3.85 ppm, δ 3.54 ppm, and δ 3.71 ppm, respectively. The H-6a and H-6b shifts can be assigned using the HSQC spectrum, with values ​​of δ 3.62 ppm and δ 3.73 ppm, respectively. After assigning the chemical shifts of the hydrogen atoms on the sugar ring, the chemical shifts of C-1 to C-6 on the sugar ring can be assigned using the HSQC correlation spectrum, with values ​​of δ 99.55 ppm, δ 71.27 ppm, δ 73.19 ppm, δ 76.82 ppm, δ 71.16 ppm, and δ 60.35 ppm, respectively. The chemical shifts of C-1 and C-4 towards the lower field indicate that these residues have undergone substitution at positions C-1 and C-4 of the sugar ring. Based on literature reports, it is inferred that the sugar residue is →4)-α-D-Glcp-(1→, labeled G 1,4The chemical shifts are assigned in Table 1. Following a similar method, the chemical shifts of the sugar residues in the anodic signal δ 5.23 / 99.87 ppm (H-1 / C-1) were deduced using HSQC and COSY, and their assignments are shown in Table 4. The chemical shifts of C-1, C-4, and C-6 shift towards the lower field, indicating that these residues have undergone substitution at positions C-1, C-4, and C-6 of the sugar ring. Based on literature reports, the sugar residue is inferred to be →4,6)-α-D-Glcp-(1→, labeled G 1,4,6 Furthermore, a cross signal of δ 4.86 / 3.43 ppm (H-1 / H-2) was found on the COSY spectrum. The anodic signal of this sugar residue was assigned as δ 4.86 / 98.67 ppm (H-1 / C-1) using the HSQC spectrum. The chemical shift of this sugar residue was deduced using COSY and HSQC, and its assignment is shown in Table 1. Based on literature reports, the sugar residue is inferred to be α-D-Glcp-(1→, labeled G... α .

[0061] A cross-peak signal was observed near the 4.36–4.65 ppm ¹H NMR and 101–104 ppm ¹H NMR regions in the HSQC anodic region. The H₂ signal with the cross-peak in this region was found in the COSY spectrum at 3.16–3.42 ppm. Based on methylation analysis results and literature reports, this is presumably an anomaly signal primarily belonging to the β-Glcp sugar residue. Anomalies of the β-Glcp sugar residues were found at δ 4.40 / 102.61 ppm, δ 4.42 / 102.61 ppm, and δ 4.60 / 102.89 ppm in the HSQC and COSY spectra. ppm, similarly derived using COSY and HSQC, combined with literature data, its chemical shift assignment is shown in Table 4. It is speculated that the sugar residues belong to →6)-β-D-Glcp-(1→, →3,6)-β-D-Glcp-(1→, β-D-Glcp-(1→, labeled as G 1,6 G 1,3,6 G β .

[0062] According to methylation analysis, the polysaccharide sample also contained t-Galp, 1,2-Galp, and 1,2-Manp linkages. However, due to the low content of these sugar residues, their signals in NMR were very weak, making further analysis impossible. 1 H and 13C is used for assignment. The coupling signals between anomeric hydrogens and carbons on each sugar residue are obtained from the HMBC long-range correlation spectrum, or the coupling signals between anomeric carbons and hydrogens on each sugar residue. Simultaneously, two protons at the connection sites of adjacent sugar residues tend to generate strong NOE signals due to their spatial proximity. The connection sequence between sugar residues can be further inferred using HMBC long-range correlation and NOESY spectra. HMBC correlation spectra of polysaccharide samples ( Figure 3 E) and NOESY spectrum ( Figure 3 As shown in F), the following coupling signals can be found in the figure:

[0063] (1) In the HMBC spectrum, there is a correlation signal peak between the H-1 (δ 4.87 ppm) of sugar residue Gal1,6 and the C-6 (δ 66.40 ppm) of sugar residue Gal1,6 (Gal1,6 H-1 / Gal1,6 C-6). In the HMBC spectrum, there is a correlation signal peak between the H-6 (δ 3.56 / 3.80 ppm) of sugar residue Gal1,6 and the C-1 (δ 97.75 ppm) of sugar residue Gal1,6 (Gal1,6 H-6a / Gal1,6 C-1 and Gal1,6 H-6b / Gal1,6 C-1). In the NOESY spectrum, there is a cross-peak between the H-1 (δ 4.87 ppm) of sugar residue Gal1,6 and the H-6 (δ 3.56 / 3.80 ppm) of sugar residue Gal1,6 (Gal1,6 H-1 / Gal1,6 C-6). H-6a and Gal1,6 H-1 / Gal1,6H-6b indicate the presence of →6)-α-D-Galp-(1→6)-α-D-Galp-(1→link; in the HMBC spectrum, the H-1 of sugar residue Gal1,6 (δ 4.87 ppm) and the C-6 of sugar residue Gal1,2,6 (δ 66.94 ppm) have a related signal peak (Gal1,6 H-1 / Gal1,2,6 C-6), and in the NOESY spectrum, the H-1 of sugar residue Gal1,6 (δ 4.87 ppm) and the H-6 of sugar residue Gal1,2,6 (δ 3.51 / 3.87 ppm) have cross peaks (Gal1,6 H-1 / Gal1,2,6 H-6a and Gal1,6 H-1 / Gal1,2,6). H-6b indicates the presence of a connection between →6)-α-D-Galp-(1→ and →2,6)-α-D-Galp-(1→, with the connection site located at position O-6; in the HMBC spectrum, the H-1 (δ 4.95 ppm) of sugar residues Gal1,2,6 and the C-6 (δ 66.94 ppm) of sugar residues Gal1,2,6 show a related signal peak (Gal1,2,6 H-1 / Gal1,2,6 C-6), and in the NOESY spectrum, the H-1 (δ 4.95 ppm) of sugar residues Gal1,2,6 and the H-6 (δ 3.51 / 3.87 ppm) of sugar residues Gal1,2,6 show cross-peaks (Gal1,2,6 H-1 / Gal1,2,6 H-6a and Gal1,2,6 H-1 / Gal1,2,6 H-1 / Gal1,2,6 H-6a). H-6b indicates the presence of →2,6)-α-D-Galp-(1→ and →2,6)-α-D-Galp-(1→ links, with the linking site located at position O-6; H-1 (δ 4.96 ppm) of sugar residue Ft in the HMBC map and C-2 (δ 77) of sugar residues Gal1,2,6.The HMBC and NOESY spectra show a related signal peak (Ft H-1 / Gal1,2,6 C-2). In the NOESY spectrum, the H-1 peak of sugar residue Ft (δ 4.96 ppm) and the H-2 peak of sugar residue Gal1,2,6 (δ 3.70 ppm) cross peaks (Ft H-1 / Gal1,2,6 H-2), indicating the presence of an α-L-Fucp-(1→ and →2,6)-α-D-Galp-(1→ link, with the linking site located at position O-2). Similarly, the HMBC and NOESY spectra show an α-D-Manp-(1→ and →2,6)-α-D-Galp-(1→ link at position O-2.

[0064] The polysaccharide methylation analysis results showed that the sugar residues →6)-α-D-Galp-(1→ and →2,6)-α-D-Galp-(1→ had the highest content, with a molar ratio of 31.448:19.849≈3:2. Additionally, terminal groups α-L-Fucp-(1→ and α-D-Manp-(1→) were attached to the O-2 position of →2,6)-α-D-Galp-(1→, with fucose as the predominant terminal group. Therefore, it can be inferred that the polysaccharide sample is mainly composed of galactan with →6)-α-D-Galp-(1→ as the main chain, with side chains at the O-2 position of some →6)-α-D-Galp-(1→, primarily fucose with a small amount of mannose.

[0065] (2) In the HMBC spectrum, there is a correlation signal peak between H-1 (δ 5.27 ppm) of sugar residue G1,4 and C-4 (δ 76.82 ppm) of sugar residue G1,4 (G1,4 H-1 / G1,4 C-4). In the NOESY spectrum, there is a cross peak between H-1 (δ 5.27 ppm) of sugar residue G1,4 and H-4 (δ 3.54 ppm) of sugar residue G1,4 (G1,4 H-1 / G1,4 H-4), indicating the presence of a connection between →4)-α-D-Glcp-(1→4)-α-D-Glcp-(1→4). In the HMBC spectrum, there is a correlation signal peak between H-1 (δ 5.27 ppm) of sugar residue G1,4 and C-4 (δ 77.35 ppm) of sugar residue G1,4,6 (G1,4 H-1 / G1,4,6). In the C-4 NOESY spectrum, there is a cross peak between the H-1 (δ 5.27 ppm) of sugar residue G1,4 and the H-4 (δ 3.48 ppm) of sugar residue G1,4,6 (G1,4 H-1 / G1,4,6). H-4 indicates the presence of a connection between →4)-α-D-Glcp-(1→ and →4,6)-α-D-Glcp-(1→), with the connection site located at position O-4. The connection signal between →4,6)-α-D-Glcp-(1→ and →4)-α-D-Glcp-(1→) at position O-4 was found in HMBC and NOESY spectra. The polysaccharide methylation analysis revealed the presence of small amounts of sugar residues →4)-α-D-Glcp-(1→ and →4,6)-α-D-Glcp-(1→) in the polysaccharide sample, with a molar ratio of 12.667:1.953≈6:1. Based on this, it can be inferred that a small amount of α-1,4-glucan structure exists in the sample, with a side chain terminal α-D-Glcp at position O-6.

[0066] (3) In the HMBC spectrum, there is a correlation signal peak between H-1 (δ 4.40 ppm) of sugar residue G1,6 and C-6 (δ 68.57 ppm) of sugar residue G1,6 (G1,6 H-1 / G1,6 C-6). In the NOESY spectrum, there is a cross peak between H-1 (δ 4.40 ppm) of sugar residue G1,6 and H-6 (δ 3.76 / 4.10 ppm) of sugar residue G1,6 (G1,6 H-1 / G1,6 H-6), indicating the presence of a connection between →6)-β-D-Glcp-(1→6)-β-D-Glcp-(1→6); In the HMBC spectrum, there is a correlation signal peak between H-1 (δ 4.40 ppm) of sugar residue G1,6 and C-6 (δ 68.57 ppm) of sugar residue G1,3,6 (G1,6 H-1 / G1,6 C-6). C-6 indicates the presence of a connection between →6)-β-D-Glcp-(1→ and →3,6)-β-D-Glcp-(1→), with the connection site located at position O-6. Furthermore, the connection signal between β-D-Glcp-(1→ and →3,6)-β-D-Glcp-(1→) at position O-3 was found in HMBC and NOESY spectra. The polysaccharide methylation analysis revealed the presence of small amounts of the sugar residues →6)-β-D-Glcp-(1→ and →3,6)-β-D-Glcp-(1→) in the polysaccharide sample, with a molar ratio of 5.382:3.129 ≈ 2:1. Based on this, it can be inferred that a small amount of β-1,6-glucan structure exists in the sample, with a side chain terminal β-D-Glcp at position O-3.

[0067] Therefore, the chemical structure of the polysaccharide from the fruiting body of *Boletus edulis* described in this application is composed of galactan with →6)-α-D-Galp-(1→ as the main chain, and contains 21%~25% fucose and mannose with side chains at the O-2 positions of →6)-α-D-Galp-(1→, as well as 20%~23% α-1,4-glucan and β-1,6-glucan structures. Its main structural elements are as follows: Figure 4 As shown.

[0068] Example 2 BDP-F Antioxidant Experiment

[0069] 1. DPPH scavenging experiment

[0070] The purified polysaccharide sample was dissolved in distilled water to prepare 5 mL solutions of different concentrations (0.1, 0.2, 0.4, 0.8, 1.6, 3.2 mg / mL) for later use. 40 mL of anhydrous ethanol was added to the DPPH free radical scavenging kit for complete dissolution. 1 mL of each polysaccharide sample solution was placed in a test tube, and 1 mL of the DPPH solution prepared half an hour prior was added and mixed well. 200 μL of each solution was pipetted into a 96-well plate, incubated in the dark for 30 minutes, and the absorbance at 517 nm was measured. Ascorbic acid solution of the same concentration as the sample was prepared as a positive control, and distilled water as a blank control. The absorbance at 517 nm was measured following the same procedure. The scavenging rate was calculated as follows: Scavenging rate (%) = [(Absorbance of blank control - Absorbance of polysaccharide sample) / Absorbance of blank control] × 100%.

[0071] 2. Hydroxyl radical scavenging experiment

[0072] This experiment improved upon the salicylic acid method. To each test tube containing 1 mL of polysaccharide sample solution of different concentrations, add 1 mL of 9 mmol / L FeSO4 solution, 1 mL of 8.8 mmol / L H2O2 solution, and 1 mL of 9 mmol / L salicylic acid-ethanol solution. Place the test tubes in a water bath at 37 ℃ for 12 min. Pipette 200 μL of each solution into a 96-well plate and measure the absorbance at 510 nm. Prepare an ascorbic acid solution of the same concentration as the sample as a positive control, and distilled water as a blank control. Follow the same procedure and measure the absorbance at 510 nm. Calculate the clearance rate: Clearance rate (%) = [(Absorbance of blank control - Absorbance of polysaccharide sample) / Absorbance of blank control] × 100%.

[0073] 3. Superoxide anion scavenging experiment

[0074] The pyrogallol auto-oxidation method was employed with slight modifications. 1 mL of 50 mM Tris-HCl solution (pH=8) was added to 1 mL of polysaccharide sample solutions of different concentrations. After mixing, 200 μL of each solution was pipetted into a 96-well plate and reacted at 25 ℃ for 20 minutes. Then, 7 μL of 5 mM pyrogallol-hydrochloric acid solution was added to each well, mixed, and reacted at 25 ℃ for 6 minutes. Finally, 7 μL of 10 mol / L concentrated hydrochloric acid was added to terminate the reaction, and the absorbance at 325 nm was measured. Ascorbic acid of the same concentration as the sample was prepared as a positive control, and distilled water as a blank control. The above steps were followed, and the absorbance at 325 nm was measured. The clearance rate was calculated as follows: Clearance rate (%) = [(Absorbance of blank group - Absorbance of polysaccharide sample) / Absorbance of blank group] × 100%.

[0075] Experimental results are as follows Figure 5 As shown, where, Figure 5 A represents the results of the DPPH scavenging experiment. Figure 5 B represents the results of the hydroxyl radical scavenging experiment. Figure 5 C represents the results of the superoxide anion scavenging experiment. The results showed that within the experimental concentration range, the scavenging ability of BDP-F against DPPH free radicals, hydroxyl free radicals, and superoxide anion free radicals increased in a dose-dependent manner, with half-maximal inhibitory concentrations (IC50 values) of 1.335 mg / mL, 0.607 mg / mL, and 3.568 mg / mL, respectively. Specifically, the single electrons of DPPH free radicals can be captured by the antioxidant components in BDP-F, converting them into stable colorless molecules; the degree of solution decolorization directly reflects the free radical scavenging efficiency. Hydroxyl free radicals (OH... - As the most potent reactive oxygen species, OH groups can indiscriminately attack biomolecules and induce cell damage, accelerate aging and pathological processes. BDP-F directly scavenges OH groups. - It may promote the transformation of superoxide anion free radicals into stable substances to block oxidative damage; and against superoxide anion free radicals (O2⁻), BDP-F can neutralize their strong oxidative activity and inhibit their damaging effects on biological macromolecules such as DNA and proteins, thereby comprehensively reducing the damage of oxidative stress to cell structure.

[0076] Example 3: In vitro gastric mucosal protective activity experiment

[0077] 1. Cell culture and viability assay

[0078] After resuscitation, cells were transferred to T25 culture flasks containing RPMI-1640 complete medium and cultured at 37 °C and 5% CO2. Once cells adhered to the flask surface, they were digested with trypsin and passaged every three days at a 1:3 ratio. Cells in logarithmic growth phase were used for subsequent experiments.

[0079] GES-1 cells were packed at 1 × 10⁻⁶ cells per well. 5 Cells were seeded at a density of [insert density here] into 96-well plates and cultured for 24 h. Then, different concentrations of BDP-F (50, 100, 200, 400, 800, and 1600 μg / mL) were added to the medium, and cells were cultured for another 24 h. After the treatment period, the old medium was removed, and 100 μL of RPMI-1640 and 10 μL of CCK-8 solution were added to each well. The resulting mixture was incubated at 37 °C for 1 h, and then the absorbance was measured at 450 nm using a microplate reader.

[0080] Experimental results are as follows Figure 6(BDP-F cytotoxicity assay results) As shown, compared with the normal control group, the overall survival rate of GES-1 cells was higher than 100% within the BDP-F concentration range of 50-1600 μg / mL. This result indicates that BDP-F has no significant toxicity to GES-1 cells within this concentration range, and may even promote cell proliferation. Therefore, based on the cell viability assay results, 200 μg / mL, 400 μg / mL, and 800 μg / mL were selected as the safe dosage ranges for BDP-F and used in subsequent experimental studies.

[0081] 2. Establish a GES-1 cell alcohol-induced injury model.

[0082] The density of the GES-1 cell suspension was 1 × 10⁻⁶. 5 Cells were seeded at a concentration of 100 μL / mL into 96-well plates and incubated at 37 ℃ with 5% CO2 for 24 hours. The old culture medium was discarded, and the cells were washed with PBS. At least six replicates were set up for each group, and 2%, 4%, 6%, 8%, and 10% ethanol solutions were added to each well, respectively. A normal control group (containing complete culture medium without ethanol) was also included. After incubation for another 3 hours, the old culture medium was discarded, and the cells were washed with PBS. 110 μL of a 1:10 mixture of CCK-8 and complete culture medium was added to each well, and the cells were incubated for another 30 min. Finally, the absorbance of each well was measured at 450 nm using a microplate reader to determine the optimal concentration of ethanol solution and incubation time for GES-1 cells to induce alcoholic injury.

[0083] Experimental results are as follows Figure 7 (The effect of ethanol on GES-1 cell viability) GES-1 cells were cultured in complete culture media containing 2%, 4%, 8%, and 10% ethanol, respectively, and incubated for 3 hours to screen the conditions for establishing an alcohol-induced injury model. The results showed that the viability of GES-1 cells gradually decreased with increasing ethanol concentration and incubation time, and significant differences in cell viability were observed at different concentrations. Specifically, with increasing ethanol concentration and prolonged incubation time, cell survival was significantly affected, exhibiting varying degrees of toxicity. Through screening, the optimal conditions for establishing a GES-1 cell alcohol-induced injury model were determined: incubation in complete culture media with 8% ethanol for 3 hours, at which point the cell viability decreased to approximately 50%, reaching a median lethality (LD50). This condition was successfully established as the standard for establishing an alcohol-induced injury model and provided a basis for subsequent experiments.

[0084] 3. Protective effect of BDP-F against alcoholic injury in GES-1 cells

[0085] The following groups were set up: a blank control group, a normal control group, a model group, and a polysaccharide group (low, medium, and high doses of purified *Boletus edulis* polysaccharide), with 6 replicates per group. The density of the GES-1 cell suspension was adjusted to 2.5 × 10⁻⁶ cells / well. 6 Cells were seeded per well in 6-well plates with 1 mL of cell suspension per well and incubated at 37 ℃ in a 5% CO2 incubator for 24 h. The old culture medium was discarded, and the cells were washed with PBS. Complete culture medium was added to the blank control group, normal control group, and model group. Different concentrations of purified *Boletus edulis* polysaccharide solution were added to the polysaccharide groups, and incubation continued for 24 h. The old culture medium was discarded, and the cells were washed with PBS. Complete culture medium was added to the blank control group and normal control group. The optimal concentration of ethanol solution was added to the model group and the low, medium, and high dose polysaccharide groups, and incubated. After modeling, the culture supernatant was collected, and the levels of TNF-α and IL-6 were measured according to the instructions of the relevant biochemical indicators. After collection, the cells were washed with PBS, and cell lysis buffer was added. The cells were incubated on ice until lysis was complete, vortexed three times during this period, and centrifuged at 12000 r / min for 20 minutes at 4 ℃. The supernatant was transferred to centrifuge tubes for later use. The collected supernatant was used to detect the levels of GSH, MDA, and SOD according to the instructions of the relevant biochemical indicators.

[0086] Experimental results are as follows Figure 8 (Preventive effect of BDP-F on EtOH-induced GES-1 cell damage) As shown, (A)-(C) represent the antioxidant level of GES-1 cells exposed to BDP-F; (D)-(E) represent the anti-inflammatory level of GES-1 cells exposed to BDP-F. Data are expressed as mean ± SD (n = 6). Compared with the control group: # p < 0.05, ## p < 0.01; compared with the model group: * p < 0.05; ** p < 0.01. The protective effect of BDP-F against ethanol-induced cell damage was systematically evaluated using key oxidative stress biomarkers and inflammatory mediators. Figure 8As shown, ethanol (EC) significantly disrupted redox homeostasis, significantly decreasing intracellular SOD levels (P < 0.01) and GSH activity (P < 0.01), while increasing MDA content (P < 0.01). BDP-F (200–800 μg / mL) dose-dependently reversed these perturbations (P < 0.05, P < 0.01). Simultaneously, BDP-F exhibited potent anti-inflammatory activity, reducing the ethanol-elevated pro-inflammatory cytokines IL-6 and TNF-α. Notably, the highest efficacy was observed at 800 μg / mL (P < 0.01), consistent with the dose-response trends for each parameter. These results collectively indicate that BDP-F alleviates ethanol-induced gastric epithelial damage through a dual mechanism: restoring antioxidant defenses (upregulation of GSH and SOD, inhibition of MDA) and mitigating the inflammatory cascade (inhibition of IL-6 and TNF-α), with efficacy directly proportional to the administered concentration.

[0087] The above analysis shows that a novel neutral polysaccharide (BDP-F) has been isolated from the fruiting body of *Boletus edulis*. The chemical structure of BDP-F was characterized by ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, one-dimensional nuclear magnetic resonance (NMR), and two-dimensional NMR. The results indicate that BDP-F is mainly composed of mannose, glucose, galactose, and fucose. Methylation and NMR analyses revealed that the glycosidic bonds of BDP-F consist of (1→6)-α-d-galactan, with the main chain composed of (1→6)-α-d-galp-(1→) residues, and branched at the O-2 position by α-L-Fucp-(1→) and α-D-Manp-(1→) residues. Notably, trace amounts of α-1,4-glucan and β-1,6-glucan structures were also identified. Furthermore, scavenging experiments using DPPH radicals, hydroxyl radicals, and superoxide anion radicals demonstrated that BDP-F possesses the potential to act as a natural antioxidant. Within the experimental concentration range, BDP-F also alleviated alcoholic GES-1 cell damage through antioxidant and anti-inflammatory effects. These results reveal the gastric protective potential and structural characteristics of Boletus edulis polysaccharides, providing a theoretical basis for their development into natural antioxidant products and functional foods or nutritional supplements with enhanced gastric protective activity.

[0088] The above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. Polysaccharide from the fruiting body of Boletus edulis, characterized in that, The main chain structure segment is: ； It contains 21%–25% side-chain fucose and mannose, and 20%–23% α-1,4-glucan and β-1,6-glucan branch fragments; among which, the structural fragments of α-1,4-glucan and β-1,6-glucan are: ； 。 2. The method for preparing polysaccharides from the fruiting bodies of Boletus edulis according to claim 1, characterized in that, The steps include the following: S1. The fruiting bodies of Boletus edulis were crushed, defatted, extracted with distilled water, concentrated, decolorized, eluted, and freeze-dried to obtain crude polysaccharide BDP; S2. BDP was separated and purified by chromatography using distilled water as the eluent to obtain the polysaccharide BDP-F from the fruiting body of Boletus edulis.

3. The white boletus fruiting body polysaccharide prepared by the preparation method according to claim 2.

4. The application of the Boletus edulis fruiting body polysaccharide according to claim 1 or 3 in the preparation of antioxidant drugs.

5. The use of the Boletus edulis fruiting body polysaccharide according to claim 1 or 3 in the preparation of drugs for repairing or protecting gastric mucosal damage.

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