Preparation method and application of polysaccharide for promoting intestinal absorption
Through pretreatment of polysaccharides, crude polysaccharide extraction and H2O2 degradation methods, polysaccharides with molecular weights of 31 to 84 kDa were prepared, which solved the problem of intestinal absorption of polysaccharides and achieved efficient and safe intestinal absorption of polysaccharides.
Patent Information
- Application Number
- CN202510727509.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-03
- Publication Date
- 2025-08-01
AI Technical Summary
Traditional methods are difficult to effectively promote the intestinal absorption of polysaccharides, and there are biosafety risks of organic solvent residues.
The pretreatment of the saccharide polysaccharide, crude polysaccharide extraction, H2O2 degradation and dialysis purification methods were used to prepare the saccharide polysaccharide with a molecular weight of 31 to 84 kDa to avoid organic solvent residues.
It significantly improved the transcellular membrane transport capacity and intestinal absorption efficiency of the polysaccharide of yambasa, significantly improved bioavailability, and was safe and non-toxic.
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Figure CN120399112A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of polysaccharide preparation, and more specifically, to a method for preparing polysaccharides that promotes intestinal absorption and its application. Background Art
[0002] As a class of natural macromolecular polymers with complex structures, polysaccharides have a wide range of biological activities. Research shows that fucoidans (such as Sargassum fusiforme polysaccharides) exhibit significant effects in aspects such as antioxidant, anti-photoaging, blood glucose homeostasis regulation, immune activation, and intestinal flora regulation. In-depth study of its oral absorption mechanism is of great significance for fully exploring its biological potential. However, the traditional view is that high-molecular polysaccharides are difficult to penetrate the intestinal epithelial barrier, resulting in limited oral absorption.
[0003] In recent years, with the rapid development of molecular biology and drug delivery technologies, researchers have explored various strategies to promote the intestinal absorption of polysaccharides. Qiu Fu'an, in "Nanonization Improves the Absorption Characteristics and Mechanisms of Hericium erinaceus Polysaccharides", used the emulsification-solvent evaporation method to prepare nano-Hericium erinaceus polysaccharide microparticles, which improved the Caco-2 cell uptake rate and transmembrane transport rate of the polysaccharides. However, this process involves organic solvent residues and has potential biosafety hazards.
[0004] Therefore, providing a green, safe, and highly absorbable method for preparing polysaccharides is an urgent problem that needs to be solved by those skilled in the art. Summary of the Invention
[0005] In view of this, the present invention provides a method for preparing polysaccharides that promotes intestinal absorption and its application. The polysaccharides prepared by the method of the present invention can significantly promote the intestinal absorption characteristics of polysaccharides, greatly improve the transmembrane transport ability of Sargassum fusiforme polysaccharides, improve their intestinal absorption efficiency, and increase the bioavailability of polysaccharides.
[0006] In order to achieve the above object, the present invention adopts the following technical solutions:
[0007] A method for preparing polysaccharides that promotes intestinal absorption, comprising the following steps:
[0008] S1: Pretreatment and degreasing purification of Sargassum fusiforme raw materials to obtain degreased powder;
[0009] S2: Extraction of crude polysaccharides: Dissolve the degreased powder in ultrapure water, extract in a 100 °C water bath, and remove the residue by vacuum filtration; then concentrate the filtrate, precipitate with alcohol, and let it stand at 4 °C. The obtained precipitate is redissolved in ultrapure water and freeze-dried to obtain crude polysaccharides;
[0010] S3: Degradation of crude polysaccharide: Dissolve the crude polysaccharide in ultrapure water and mix it with H2O2 solution. In the resulting mixed system, the final concentration of polysaccharide is controlled at 1 - 2.5 mg / mL, and the final concentration of H2O2 is controlled at 70 - 100 mmol / L. Place the mixed system in a UVB ultraviolet irradiator for degradation treatment, evaporate and concentrate, dialyze and purify, and freeze-dry to obtain polysaccharide that promotes intestinal absorption.
[0011] Among them, the parameters of the degradation treatment described in S3 are irradiation temperature 20 - 30 °C, irradiation power 950 μW / cm 2 , and irradiation time 30 - 120 min.
[0012] Preferably, the raw material pretreatment described in step S1 is to wash Sargassum fusiforme to remove surface salts, sediment and attached organisms, drain the water, dry it to constant weight in an oven at 60 °C, and then pulverize it through a 60-mesh sieve to obtain ultrafine powder.
[0013] Preferably, the defatting and purification described in step S1 is to mix the ultrafine powder with 95% ethanol at a mass-to-volume ratio of 1:4, reflux and extract at 82 ± 2 °C for 3 times, 1.5 h each time, collect the precipitate and dry it at 60 °C to obtain defatted powder.
[0014] Preferably, step S2 is specifically to dissolve the defatted powder in ultrapure water, with the mass-to-volume ratio of defatted powder to ultrapure water being 1:50, then extract in a hot water bath at 100 °C for 4 h, and remove the residue by vacuum filtration; then rotary evaporate and concentrate the filtrate to 1 / 5 of the original volume, slowly add 95% ethanol to a final concentration of 80%, mix well and let stand at 4 °C for 12 h, and the precipitate obtained after centrifugation is redissolved with ultrapure water and freeze-dried to obtain crude polysaccharide.
[0015] Preferably, the dialysis purification described in step S3 uses a dialysis bag with a molecular weight cut-off of 3 - 5 kDa for dialysis purification for 48 h.
[0016] Preferably, the freeze-drying step in step S3 is carried out at -60 to -20 °C, and the drying time is 24 h.
[0017] Another object of the present invention is to provide Sargassum fusiforme polysaccharide prepared by the above preparation method.
[0018] Another object of the present invention is to provide the application of the above preparation method in the preparation of nutritional supplements, functional foods or health products with the function of promoting polysaccharide intestinal absorption.
[0019] Beneficial effects:
[0020] The molecular weight of the Sargassum fusiforme polysaccharide prepared by the method of the present invention is 31-84 kDa, the total sugar content is 51.52-53.03%, its transmembrane transport ability is greatly improved, the intestinal absorption efficiency is significantly improved, and the bioavailability is significantly increased. This preparation method has no residual organic solvents, is green, safe and efficient. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative work.
[0022] Figure 1 It is the ultraviolet spectrum diagram of the amination and FITC labeling process of the Sargassum fusiforme polysaccharide in the embodiment of the present invention.
[0023] Figure 2 It is the fluorescence microscope diagram of the comparison of the Sargassum fusiforme polysaccharide before and after fluorescence labeling in the embodiment of the present invention.
[0024] Figure 3 It is the cytotoxicity evaluation of three groups of polysaccharide samples on the Caco-2 cell line by the MTT method.
[0025] Figure 4 It is the cumulative transport amount of FA, FB, and FC in the Caco-2 cell monolayer model (AP-BL) in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.
[0027] Example 1
[0028] (1) Pretreatment of raw materials and degreasing and purification: Place fresh Sargassum fusiforme in an ultrasonic cleaner and ultrasonically treat it 3 times with deionized water at 40 °C (10 minutes each time, power 200 W) to remove surface salts, sediment, and attached organisms. Drain the water and dry it to constant weight in an oven at 60 °C. Use a pulverizer to crush the dried Sargassum fusiforme into a coarse powder with a particle size ≤ 2 mm, and then use a low-temperature vibrating cell-level ultrafine pulverizer to perform ultrafine pulverization for 10 minutes and pass through a 60-mesh sieve. Take 100 g of the ultrafine powder and mix it with 400 mL of 95% ethanol by volume. Reflux and extract it at a gentle boil at 82 ± 2 °C for 3 times (1.5 hours each time, and add ethanol intermittently to the initial liquid level), collect the precipitate and dry it at 60 °C to obtain degreased Sargassum fusiforme powder.
[0029] (2) Extraction of crude polysaccharide from Sargassum fusiforme: Mix the degreased Sargassum fusiforme powder with ultrapure water at a ratio of 1:50 (g / mL), and mechanically stir and extract it in a constant temperature water bath at 100 °C for 4 hours. Filter under reduced pressure to remove the residue. Rotate and evaporate the filtrate to concentrate it to 1 / 5 of the original volume, and then slowly add 95% ethanol until the final ethanol concentration is 80% (v / v). After stirring and mixing evenly, let it stand at 4 °C for 12 hours. After standing, centrifuge and discard the supernatant. Redissolve the precipitate with ultrapure water and freeze-dry it under vacuum to obtain crude polysaccharide from Sargassum fusiforme.
[0030] ((3) UV / H2O2 degradation: Dissolve the crude polysaccharide from Sargassum fusiforme in ultrapure water and mix it with an H2O2 solution to obtain a mixed solution. In the mixed system, the final concentration of the polysaccharide is controlled at 1 mg / mL, and the final concentration of H2O2 is controlled at 70 mmol / L. Place the mixed solution in a UVB ultraviolet radiation instrument (irradiation temperature 20 - 30 °C, irradiation power 950 μW / cm 2 ) and treat it for 30 minutes respectively. Then, rotate and evaporate to concentrate to remove the solvent, and then use a dialysis bag with a molecular weight cut-off of 3 - 5 kDa to dialyze and purify it for 48 hours, and freeze-dry it (at -60 to -20 °C, the drying time is 24 hours) to obtain the degraded polysaccharide, named B.
[0031] Example 2
[0032] (1) Pretreatment of raw materials and degreasing and purification: Place fresh Sargassum fusiforme in an ultrasonic cleaner and ultrasonically treat it 3 times with deionized water at 40 °C (10 minutes each time, power 200 W) to remove surface salts, sediment, and attached organisms. Drain the water and dry it to constant weight in an oven at 60 °C. Use a pulverizer to crush the dried Sargassum fusiforme into a coarse powder with a particle size ≤ 2 mm, and then use a low-temperature vibrating cell-level ultrafine pulverizer to perform ultrafine pulverization for 10 minutes and pass through a 60-mesh sieve. Take 100 g of the ultrafine powder and mix it with 400 mL of 95% ethanol by volume. Reflux and extract it at a gentle boil at 82 ± 2 °C for 3 times (1.5 hours each time, and add ethanol intermittently to the initial liquid level), collect the precipitate and dry it at 60 °C to obtain degreased Sargassum fusiforme powder.
[0033] (2) Extraction of crude polysaccharides from Sargassum fusiforme: Defatted Sargassum fusiforme powder was mixed with ultrapure water at a ratio of 1:50 (g / mL), mechanically stirred and extracted in a constant temperature water bath at 100 °C for 4 h, and the residue was removed by vacuum filtration. The filtrate was concentrated by rotary evaporation to 1 / 5 of the original volume, and then 95% ethanol was slowly added until the final ethanol concentration reached 80% (v / v). After stirring and mixing evenly, it was left to stand at 4 °C for 12 h. After standing, the supernatant was discarded by centrifugation, and the precipitate was redissolved with ultrapure water and freeze-dried under vacuum to obtain crude polysaccharides from Sargassum fusiforme.
[0034] (3) UV / H2O2 degradation: The crude polysaccharides from Sargassum fusiforme were dissolved in ultrapure water and mixed with H2O2 solution to obtain a mixed solution. In the mixed system, the final concentration of polysaccharides was controlled at 2.5 mg / mL, and the final concentration of H2O2 was controlled at 100 mmol / L. The mixed solution was placed in a UVB ultraviolet radiation instrument (irradiation temperature 20 - 30 °C, irradiation power 950 μW / cm 2 ) and treated for 120 min respectively, then the solvent was removed by rotary evaporation and concentration, and then dialyzed and purified with a dialysis bag with a molecular weight cut-off of 3 - 5 kDa for 48 h, and freeze-dried (-60 to -20 °C, drying time was 24 h) to obtain degraded polysaccharides, named C.
[0035] Comparative Example 1
[0036] Step (3) in Example 1 was omitted, and the other steps were the same as those in Example 1 to obtain crude polysaccharides from Sargassum fusiforme, named A.
[0037] Effect Example 1
[0038] 1. Determination of polysaccharide molecular weight and total sugar content
[0039] The molecular weight of the polysaccharide was determined by high performance gel permeation chromatography. The specific experimental steps were as follows: 4.0 mg of Sargassum fusiforme polysaccharide sample was accurately weighed, dissolved in 0.02 mol / L KH2PO4 buffer solution, filtered through a 0.22 μm aqueous filter membrane and injected. A chromatographic column TSKgel G-6000PWXL (7.8 × 300 mm) and TSKgel G-3000PWXL (7.8 × 300 mm) were used in series, the column temperature was set at 35 ± 1 °C; the mobile phase was 0.02 mol / L KH2PO4 solution, the flow rate was 0.5 mL / min; a Waters2414 differential refractive index detector was used; the injection volume was 30 μL. A molecular weight - elution time standard curve was established with a series of dextran standards (4.66 - 556 kDa), and the sample molecular weight was calculated through the standard curve based on the elution volume. The results are shown in Table 1.
[0040] The total sugar content of the polysaccharide was determined by the phenol-sulfuric acid method. The specific experimental steps were as follows: Using fucose as the standard, a series of standard solutions with concentrations of 0.02, 0.04, 0.06, 0.08, and 0.1 mg / mL were prepared respectively. Take 1 mL of each concentration standard solution, sequentially add 1 mL of 5% (w / v) phenol solution and 5 mL of concentrated sulfuric acid, mix well and let it stand for reaction for 20 min. Use a UV-visible spectrophotometer to measure the absorbance value of the reaction solution at a wavelength of 490 nm. Draw a standard curve with the fucose concentration as the abscissa and the absorbance value as the ordinate, and establish a linear regression equation.
[0041] Prepare a 0.1 mg / mL solution of Sargassum fusiforme polysaccharide, accurately pipette 1 mL, and perform the same treatment and measure the absorbance value according to the above color reaction method. Substitute the measured absorbance value into the standard curve equation to calculate the total sugar content of the polysaccharide sample. The results are shown in Table 1.
[0042] Table 1
[0043]
[0044] Table 1 presents the determination results of the average molecular weight and total sugar content of three groups of polysaccharide samples. The experimental results show that after UV / H2O2 degradation treatment, the molecular weight of Sargassum fusiforme polysaccharide shows a significant decreasing trend (P < 0.05), and an obvious molecular weight gradient distribution (high, medium, low) is formed among the three groups of samples, which establishes a basic model for studying the effect relationship between degradation and absorption. The total sugar content of each group of samples is maintained within the range of 51 - 62 wt%, and no significant difference is found after statistical analysis (P > 0.05), indicating that the UV / H2O2 degradation treatment can effectively regulate the molecular weight of polysaccharide while keeping the total sugar content of polysaccharide unaffected.
[0045] 2. Identification of Fluorescently Labeled Polysaccharide
[0046] (1) Amination of polysaccharide: Weigh A, B, and C (200 - 400 mg) obtained from the examples and comparative examples respectively and dissolve them in PBS solution with a pH of 8.0 and a concentration of 0.2 mol / L (8 - 15 mL). Sequentially add Tyramine (200 - 400 mg) and NaBH3CN (75 - 150 mg). The mixed solution reacts at 37 °C for three days, centrifuge to take the supernatant, and purify by dialysis. Add absolute ethanol, place it at 4 °C for 12 h, centrifuge to take the precipitate, and freeze-dry to obtain the aminated polysaccharide samples, named A-A, A-B, and A-C respectively.
[0047] (2) Covalent coupling of polysaccharide with FITC: The aminated polysaccharide sample was dissolved in a 0.5 mol / L NaHCO3 solution (20 - 40 mL), FITC (15 - 25 mg) was added, and the reaction was carried out in the dark at 37 °C in a constant temperature shaker for 24 h. After dialysis purification, absolute ethanol was added, and it was left at 4 °C for 12 h. The precipitate was collected by centrifugation, and the dry fluorescently labeled polysaccharide was obtained by nitrogen blowing, named FA, FB, and FC respectively.
[0048] (3) Prepare solutions of FA, FB, and FC (concentration 0.1 mg / mL), and use an ultraviolet spectrophotometer to scan the ultraviolet-visible light spectrum of the solution in the range of 200 - 600 nm.
[0049] (4) Take 20 - 50 μL of the FA, FB, and FC solutions (same concentration as above) and drop them on a glass slide. Slowly cover the glass slide to make a sample of the fluorescently labeled polysaccharide, and observe its fluorescence signal through a fluorescence microscope.
[0050] The aminated and FITC-labeled Sargassum fusiforme polysaccharides were characterized by ultraviolet-visible spectroscopy, and the results are shown in the appendix Figure 1 . Compared with the untreated polysaccharide, the aminated polysaccharides (A-A, A-B, A-C) showed characteristic absorption peaks at 280 nm, indicating that amino groups had been successfully introduced into the polysaccharide molecular structure. Further, the FITC-labeled polysaccharides (FA, FB, FC) showed characteristic absorption peaks at 490 nm, and this spectral change confirmed the effective binding of FITC to the polysaccharide molecule.
[0051] Appendix Figure 2 shows the fluorescence microscopy imaging results of the three groups of samples FA, FB, and FC. The results showed that the FITC-labeled experimental groups (FA, FB, FC) all showed obvious green fluorescence signals, while no fluorescence was detected in the unlabeled control groups (A, B, C), confirming that effective fluorescence labeling was achieved in all three groups of samples, meeting the technical requirements of subsequent tracer experiments.
[0052] 3. Cytotoxicity determination of polysaccharide on Caco-2 cells
[0053] Caco-2 cells in the logarithmic growth phase were seeded at 1.0×10 per well 4Cells were inoculated into a 96-well plate at a density of [density value], cultured in an incubator at 37°C with 5% CO₂ for 12 h, and the culture medium was aspirated. A control group and sample groups were set up. Among them, 100 μL of complete medium was added to the control group, and 100 μL of different sample solutions (concentrations of 125, 250, 500, 1000 μg / mL) were added to the sample groups. The samples were prepared with complete medium, and after being fully dissolved, they needed to be filtered through a 0.22 μm filter membrane. After culturing for 12 h, the supernatant was aspirated, 50 μL of MTT solution was added to each well, and the cells were incubated in the dark in the incubator for 4 h. The MTT solution was aspirated, 150 μL of dimethyl sulfoxide solution (DMSO) was added to each well to dissolve formazan, and it was shaken to fully dissolve. The absorbance of each well was measured at 570 nm, and the cell survival rate was calculated, with the absorbance of the control group taken as the 100% standard.
[0054] Appendix Figure 3 shows the results of cytotoxicity evaluation of three polysaccharide samples on the Caco-2 cell line using the MTT method. The experimental data indicate that within the concentration range of 125 - 1000 μg / mL, the cell survival rate of all tested groups remained above 80%. This finding not only confirmed that the polysaccharide samples had no obvious toxic effect on Caco-2 cells within this concentration range but also further verified the biocompatibility of the fluorescence labeling process, ensuring that the labeled polysaccharide samples were suitable for subsequent biological function research and experimental applications without affecting cell viability.
[0055] 4. Evaluation of Transmembrane Transport Efficiency Based on the Caco-2 Cell Monolayer Model
[0056] (1) Construction of the 21-day Caco-2 cell monolayer model: Caco-2 cells in the logarithmic growth phase (density of 0.8×10 5 -1.5×10 5 cell / cm 2 ) were inoculated onto the AP side of a Transwell polycarbonate membrane (pore size 0.4 μm), and complete medium was added to the BL side. They were cultured in a cell incubator at 37°C with 5% CO₂ for 21 days. The culture medium was changed daily, and the morphology of Caco-2 cells was observed. The model resistance value, alkaline phosphatase activity ratio, and fluorescein sodium permeability were measured, and the model with indicators meeting the requirements was selected for subsequent experiments.
[0057] Through this method, the present invention successfully constructed a Caco-2 cell monolayer model for polysaccharide absorption and transport research. On the 21st day of culture, it was found through morphological observation that Caco-2 cells formed a complete monolayer membrane structure with good tight junctions between cells, meeting the morphological requirements for absorption and transport experiments. The detection results of the relevant indicators of this model are as follows: the transmembrane resistance value was 865.50 ± 26.67 Ω·cm 2, the alkaline phosphatase activity ratio (AP / BL) is greater than 1.5, and the apparent permeability coefficient of sodium fluorescein (AP-BL) is less than 1×10 -6 cm / s. The above indicators all meet the establishment standards of the Caco-2 cell monolayer model and can be used for subsequent experimental studies.
[0058] (2) Time-dependent transport experiment analysis: Add HBSS buffer containing FA, FB, and FC to the AP side of the Caco-2 cell monolayer model, and the BL side is the blank HBSS buffer. At the preset time points from 0 to 240 min, collect the transport medium from the BL side for detection, and calculate the cumulative transport amount of the fluorescently labeled polysaccharide in the Caco-2 cell monolayer.
[0059] Appendix Figure 4 shows the change trend of the cumulative transport amount (AP-BL direction) of the polysaccharide in the Caco-2 cell model over time (0-240 min). The experimental results show that at the same time point, there are significant differences in the cumulative transport amounts of the three groups of samples: FA < FB < FC (P<0.05). Especially at 240 min, the transport amount of FC increased by 55.6% compared with that of FA without degradation treatment. This result confirms that the molecular weight-regulated degradation technology can significantly enhance the transmembrane transport efficiency of polysaccharides.
[0060] 5. Analysis of the intestinal absorption characteristics of polysaccharides based on the everted gut sac model
[0061] (1) Construction and incubation of the everted gut sac model: After fasting a healthy rat for 12 hours, anesthetize and laparotomize it. Quickly intercept 7-10 cm of intestinal segments (duodenum, jejunum, ileum, colon) and wash them. Carefully separate the mesentery and fat on the surface of the intestinal segments, and turn the intestinal segments inside out to construct everted gut sacs. Fix the proximal end of the gut sac on a polyethylene catheter and tie it firmly with a thin thread. Also tie the distal end with a thin thread to form a closed sac-like intestinal tube. Inject Krebs-Ringer buffer into the gut sac and suspend it in a test tube containing Krebs-Ringer buffer. Provide a constant water bath at 37°C and a mixed gas of 95% oxygen and 5% carbon dioxide for the gut sac, and equilibrate for 10 min.
[0062] (2) Determination of the transport of fluorescently labeled polysaccharides in the everted gut sac model: After equilibration and leak detection, replace the nutrient solution in the test tube with the test solution containing FA, FB, and FC. After 120 min, collect the fluid inside the gut sac for detection and calculate its transport rate (see Table 2).
[0063] Table 2
[0064]
[0065] Table 2 presents the absorption rates (%) of FA, FB, and FC in different intestinal segments. Data analysis shows that: (1) The absorption rates of Sargassum fusiforme polysaccharide in the duodenum, jejunum, and ileum are significantly higher than those in the colon (P<0.05); (2) Except for the colon, significant gradient differences of C>B>A in absorption rates are presented in each intestinal segment (P<0.05). These results confirm that the bioavailability of Sargassum fusiforme polysaccharide can be effectively improved by the UV / H2O2 degradation technology.
[0066] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference can be made to each other.
[0067] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A method for preparing a polysaccharide that promotes intestinal absorption, characterized in that, It includes the following steps: S1: Pretreatment and degreasing purification of Sargassum fusiforme raw materials to obtain degreased powder; S2: Extraction of crude polysaccharide: Dissolve the degreased powder in ultrapure water, extract it in a hot water bath at 100 °C, and remove the residue by vacuum filtration; then concentrate the filtrate, precipitate with alcohol, and let it stand at 4 °C. The obtained precipitate is redissolved with ultrapure water and freeze-dried to obtain crude polysaccharide; S3: Degradation of crude polysaccharide: Dissolve the crude polysaccharide in ultrapure water, mix it with H2O2 solution. In the obtained mixed system, the final concentration of polysaccharide is controlled at 1 - 2.5 mg / mL, and the final concentration of H2O2 is controlled at 70 - 100 mmol / L; Place the mixed system in a UVB ultraviolet irradiator for degradation treatment, evaporate and concentrate, dialyze and purify, and freeze-dry to obtain polysaccharide that promotes intestinal absorption; Among them, the parameters of the degradation treatment described in S3 are an irradiation temperature of 20 to 30 °C, an irradiation power of 950 μW / cm 2 , and an irradiation time of 30 to 120 min.
2. The method for preparing polysaccharide for promoting intestinal absorption according to claim 1, wherein, In step S1, the raw material pretreatment is to wash Sargassum fusiforme to remove surface salts, sediment and attached organisms, drain the water, dry it to constant weight in an oven at 60 °C, and then pulverize it through a 60-mesh sieve to obtain ultrafine powder.
3. The method for preparing polysaccharide for promoting intestinal absorption according to claim 1, characterized in that, In step S1, the degreasing purification is to mix the ultrafine powder with 95% ethanol at a mass-to-volume ratio of 1:4, reflux and extract it at 82 ± 2 °C for 3 times, 1.5 hours each time, collect the precipitate and dry it at 60 °C to obtain degreased powder.
4. The method for preparing the polysaccharide promoting intestinal absorption according to claim 1, wherein Step S2 is specifically to dissolve the degreased powder in ultrapure water, with a mass-to-volume ratio of degreased powder to ultrapure water of 1:50, then extract it in a hot water bath at 100 °C for 4 hours, and remove the residue by vacuum filtration; then rotate and evaporate the filtrate to 1 / 5 of the original volume, and slowly add 95% ethanol to a final concentration of 80%, mix well and let it stand at 4 °C for 12 hours. The precipitate obtained after centrifugation is redissolved with ultrapure water and freeze-dried to obtain crude polysaccharide.
5. The method for preparing a polysaccharide for promoting intestinal absorption according to claim 1, characterized in that, In step S3, the dialysis purification uses a dialysis bag with a molecular weight cut-off of 3 - 5 kDa for dialysis purification for 48 hours.
6. The method for preparing a polysaccharide for promoting intestinal absorption according to claim 1, characterized in that, The freeze-drying step in step S3 is carried out at -60 to -20 °C, and the drying time is 24 hours.
7. Sargassum fusiforme polysaccharide prepared by the preparation method according to any one of claims 1 - 6.
8. Use of the preparation method according to any one of claims 1 - 6 in the preparation of nutritional supplements, functional foods or health products having the effect of promoting the intestinal absorption of polysaccharides.