Macromolecular dried longan pulp heteropolysaccharide with hypoglycemic characteristic, and preparation method and application thereof

Abstract

The invention relates to the technical field of extracts, in particular to macromolecular dried longan pulp heteropolysaccharide with a blood sugar reducing characteristic and a preparation method and application thereof. The preparation method comprises the following steps: drying the longan pulp, homogenizing the dried pulp, adding distilled water, performing hot water extraction, filtering through gauze, and separating the dried longan pulp heteropolysaccharide with the blood sugar reducing characteristic and the molecular weight of more than 100kDa from the dried longan pulp by combining processes such as dialysis, ultrafiltration interception and the like. The dry longan pulp polysaccharide is extracted by adopting a hot water extraction method, the dry longan pulp polysaccharide is separated by adopting an ultrafiltration interception system device, the main component DLP of the dry longan pulp polysaccharide can inhibit starch digestive enzymes, model cell insulin resistance can be improved, and human intestinal flora composition can be changed. The beverage has the functions of reducing blood sugar and regulating intestinal flora.

Description

Technical Field

[0001] The present invention relates to the technical field of extracts, and particularly relates to a macromolecular dried longan pulp heteropolysaccharide with hypoglycemic properties, a preparation method and uses thereof. Background Art

[0002] The International Diabetes Federation estimates that by 2035, approximately 643 million people may be affected by diabetes. Currently, diabetes is mainly treated clinically with hypoglycemic drugs or insulin injections. However, most chemically synthesized hypoglycemic drugs have certain side effects, and long-term use of these drugs will lead to various adverse reactions. Therefore, it is becoming increasingly attractive to screen active ingredients with no toxic side effects, high efficiency and improved diabetes treatment from natural source plants.

[0003] Longan is an important fruit resource in southern China and is included in the list of "medicinal and edible homologous substances" in China due to its significant tonic function. Its functions of calming the nerves and nourishing the heart, and replenishing qi and blood are well-known. Currently, a large number of studies have shown that polysaccharides have activities such as immunomodulation, antioxidant, anti-tumor and anti-inflammatory. It is reported that longan pulp polysaccharide has significant immunomodulatory activity, can significantly promote macrophage phagocytosis and increase the secretion of its immunomodulatory factors. However, there are few reports on the hypoglycemic activity of longan pulp polysaccharide. For example, Liu Huijun et al. published a study on the optimization of the ultra-fine pulverization-enzymatic hydrolysis extraction process of longan pulp polysaccharide and its immunological activity (Liu Huijun, Huang Fei, Zhang Ruifen, etc. Optimization of the ultra-fine pulverization-enzymatic hydrolysis extraction process of longan pulp polysaccharide and its immunological activity [J]. Journal of Chinese Institute of Food Science and Technology, 2020, 20(03): 112-120. DOI: 10.16429 / j.1009-7848.2020.03.015.). They used ethanol precipitation combined with ultra-fine pulverization-enzymatic assisted extraction of longan polysaccharide to obtain an acidic longan polysaccharide mainly composed of arabinose, galactose and rhamnose, with a solubility of 45.6±0.28 mg / mL, which has a good effect on activating the ability of macrophages to secrete NO, TNF-α and IL-1β, indicating that the polysaccharide has good immunomodulatory activity. However, this acidic polysaccharide does not have hypoglycemic efficacy and has a low solubility. Patent document CN116854835A once disclosed a highly immunologically active acetylated longan water-soluble glucan and its preparation method and uses. It obtained an acetylated longan water-soluble glucan with better immunological activity by modifying the glucan in longan with acetic anhydride. However, this polysaccharide is a glucan, not a heteropolysaccharide, and this polysaccharide does not have hypoglycemic efficacy.

[0004] Patent document CN107987177A once disclosed a method for separating and purifying hypoglycemic longan pulp polysaccharide, which uses petroleum ether, ethyl acetate, and n-butanol to extract longan pulp. The separated and purified small-molecule longan pulp polysaccharide has an inhibitory effect on α-glucosidase. However, it uses organic solvents such as petroleum ether, ethyl acetate, n-butanol, and ethanol, which have safety hazards such as flammability, volatility, and toxicity hazards, as well as environmental protection problems.

[0005] On April 1, 2025, with "longan pulp and polysaccharide and various and glucose" as the abstract keywords and checking the box to allow synonym expansion, a search was conducted in the Chinese Patent Publication Database, and no relevant literature was found.

[0006] On April 1, 2025, an abstract search was conducted on CNKI with "longan pulp and polysaccharide and various and glucose", and no relevant literature was found.

[0007] On April 1, 2025, a search was conducted on the website of the United States Patent and Trademark Office with "longan pulp with heteropolysaccharide with various with glucose", and no relevant literature was found; the search URL is https: / / ppubs.uspto.gov / pubwebapp / .

[0008] On April 1, 2025, a search was conducted on https: / / patentscope2.wipo.int / of WIPO with "longan pulp and heteropolysaccharide and various and glucose", and no relevant literature was found.

[0009] On April 1, 2025, a search was conducted on the website of the Japan Patent Office https: / / www.j-platpat.inpit.go.jp / with "longan pulp and heteropolysaccharide and various and glucose", and no relevant literature was found.

[0010] It is completely different from the concept of this patent. Summary of the Invention

[0011] Purpose of the Invention: To provide a macromolecular dried longan pulp heteropolysaccharide with hypoglycemic properties, a preparation method, and uses with better effects. The specific purpose can be seen in the multiple substantial technical effects in the specific implementation part.

[0012] To achieve the above object, the present invention adopts the following technical solutions: A preparation method of a macromolecular dried longan pulp heteropolysaccharide with hypoglycemic properties, characterized in that the preparation method includes drying longan pulp, adding distilled water after homogenizing the dried pulp, performing hot water extraction and then filtering through gauze, and separating a dried longan pulp heteropolysaccharide with a molecular weight greater than 100 kDa and having hypoglycemic properties from the dried longan pulp by combining processes such as dialysis and ultrafiltration retention.

[0013] A further technical solution of the present invention lies in that the preparation method includes the following steps: S1. Drying longan pulp to obtain dried longan pulp, homogenizing longan pulp, adding the slurry to distilled water for hot water extraction, concentrating and then centrifuging, and performing dialysis and centrifugation on the supernatant to obtain dried longan pulp crude polysaccharide; S2. Using an ultrafiltration system device to perform ultrafiltration retention on the obtained dried longan pulp polysaccharide, concentrating and freeze-drying to obtain the macromolecular dried longan pulp heteropolysaccharide with hypoglycemic properties.

[0014] A further technical solution of the present invention lies in that in S1, the longan pulp is dried to a water content of 18%; 4600 mL of distilled water is added, and hot water extraction is performed at 80 °C for 3 h; it is concentrated under reduced pressure to a volume of 500 mL; centrifugation is performed at 4 °C under the conditions of 10000 g for 10 min to obtain the supernatant; the supernatant is dialyzed using a dialysis bag with a molecular weight of 6000 Da in a 4 °C refrigerator for 3 days, and ultrapure water is replaced every 8 h.

[0015] A further technical solution of the present invention lies in that in S1, the longan pulp is dried to a water content of 18%; 4600 mL of distilled water is added, and hot water extraction is performed at 80 °C for 3 h; it is concentrated under reduced pressure to a volume of 500 mL; centrifugation is performed at 4 °C under the conditions of 10000 g for 10 min to obtain the supernatant; the supernatant is dialyzed using a dialysis bag with a molecular weight of 6000 Da in a 4 °C refrigerator for 3 days, and ultrapure water is replaced every 8 h.

[0016] A further technical solution of the present invention lies in that in S2, an ultrafiltration retention system device is adopted, and 1000 mL of the dried longan pulp polysaccharide solution is passed through a filter membrane with a molecular weight Mw of 100 kDa, and after retaining 200 mL of the solution, a dried longan pulp heteropolysaccharide solution with a molecular weight greater than 100 kDa is obtained.

[0017] A macromolecular dried longan pulp heteropolysaccharide with hypoglycemic properties, characterized in that the longan pulp heteropolysaccharide has high solubility and high purity, its total sugar content is 82.21±1.25%, the uronic acid content is 4.13±0.32%, the protein content is 3.06±0.31%, and the solubility reaches 87.2±0.72 mg / mL.

[0018] A further technical solution of the present invention is that the heteropolysaccharide is composed of a variety of monosaccharides connected by glycosidic bonds, and its components include glucose, galactose, arabinose, xylose, rhamnose, mannose, as well as galacturonic acid and glucuronic acid.

[0019] A further technical solution of the present invention is that the molar ratio of glucose, galactose, arabinose, xylose, rhamnose, mannose, galacturonic acid and glucuronic acid is 34.2:27.3:20.6:4.2:3.0:2.3:6.5:1.3.

[0020] Use of hot water extraction combined with ultrafiltration retention for dried longan pulp heteropolysaccharide in the preparation of substances for inhibiting α-amylase, improving glucose consumption and hepatic glycogen synthesis in insulin-resistant cells, regulating the human intestinal flora, and preparing hypoglycemic and / or improving intestinal flora disorders.

[0021] A food, drug or health product, characterized in that its ingredients contain the preparation method of the macromolecular dried longan pulp heteropolysaccharide with hypoglycemic properties as described in any one of claims 1-5.

[0022] The present invention adopting the above technical solution has the following beneficial effects compared with the prior art: (1) The present invention uses the hot water extraction method to extract the dried longan pulp polysaccharide, and uses the ultrafiltration retention system device to separate the dried longan pulp polysaccharide. Its main component is DLP. This polysaccharide can inhibit starch digestive enzymes, improve insulin resistance in model cells, and change the composition of the human intestinal flora. It has the functions of hypoglycemia and regulating intestinal flora.

[0023] (2) The present invention uses ultrafiltration retention to retain the dried longan pulp heteropolysaccharide and then preliminarily identifies the structure of DLP through monosaccharide composition and molecular weight distribution, which is beneficial for further studying its activity. Description of the Drawings

[0024] In order to further illustrate the present invention, the following is further described in conjunction with the drawings: Figure 1 For the monosaccharide composition results of the examples; Figure 2 For the molecular weight distribution and average molecular weight results of the examples; Figure 3 For the α-amylase inhibition rate results of the examples; Figure 4 Results of glucose consumption by insulin resistance model cells for the examples; Figure 5 Results of hepatic glycogen synthesis by insulin resistance model cells for the examples; Figure 6 Initial in vitro flora abundance and flora abundance at the phylum level after 24 h of glycolysis for the examples and comparative examples; Figure 7 Initial in vitro flora abundance and flora abundance at the genus level after 24 h of glycolysis for the examples and comparative examples. Detailed implementation manners

[0025] The present invention will be further clarified below in conjunction with the accompanying drawings and detailed implementation manners. It should be understood that the following detailed implementation manners are only used to illustrate the present invention and not to limit the scope of the present invention.

[0026] The present invention uses longan pulp as a raw material, dries it, and obtains the main component DLP through hot water extraction combined with ultrafiltration retention. Then, its effect of inhibiting starch digestive enzymes, improving insulin resistance of HepG2 liver cancer cells, and its impact on human intestinal microorganisms are explored through in vitro simulated fermentation. Subsequently, gel chromatography and ion chromatography are used to preliminarily identify the structure of DLP, providing a theoretical basis for further exploring the active ingredients in dried longan pulp and elucidating the active action mechanism of dried longan pulp. Examples

[0027] This example provides a macromolecular dried longan pulp heteropolysaccharide with hypoglycemic properties, and its preparation raw materials are as follows: longan pulp.

[0028] The preparation method of the macromolecular dried longan pulp heteropolysaccharide with hypoglycemic properties is as follows: (1) Remove the branches from fresh longan pulp and dry it in a heat pump drying oven at 65 °C until the moisture content is about 18% to obtain dried longan pulp; (2) Take 100 g of dried longan pulp, put it into a blender, add 300 mL of distilled water, and stir for 10 min to obtain longan pulp slurry for standby; (3) Under the condition of a water bath at 80 °C, add 4600 mL of distilled water and the longan pulp slurry for extraction for 3 h. Collect the extract and filter it with a 200-mesh gauze. Concentrate the filtrate under reduced pressure at 60 °C to a volume of 500 mL. Centrifuge the concentrated solution at 4 °C under the conditions of 10000 g for 10 min to obtain the supernatant. Dialyze the supernatant with a dialysis bag with a Mw of 6000 Da in a 4 °C refrigerator for 72 h, and replace the ultrapure water every 8 h. After dialysis, centrifuge the dialysate at 4 °C under the conditions of 10000 g for 10 min to remove the precipitate, and collect the supernatant to obtain the dried longan pulp polysaccharide solution.

[0029] (4) An ultrafiltration retention system device was adopted. 1000 mL of the dried longan pulp polysaccharide solution was passed through a filter membrane with a molecular weight Mw of 100 kDa, and after retaining 200 mL of the solution, a heteropolysaccharide solution of dried longan pulp with a molecular weight greater than 100 kDa was obtained. The obtained solution was concentrated and freeze-dried. The polysaccharide with a molecular weight greater than 100 kDa is the hypoglycemic heteropolysaccharide of dried longan pulp.

[0030] Comparative Example 1 This comparative example provides a commercially available polysaccharide - fructooligosaccharide.

[0031] Comparative Example 2 This comparative example is a blank control, that is, no polysaccharide is added.

[0032] Physicochemical properties and structure determination of macromolecular heteropolysaccharide DLP of dried longan pulp Experimental Example 1 Determination of physicochemical properties and structure of polysaccharide: The sugar content of the polysaccharide component was determined by the phenol-sulfuric acid method, the uronic acid content was determined by the m-hydroxybiphenyl method, the protein content was determined by the Coomassie brilliant blue method, the solubility was determined by the dissolution-drying specific gravity method, the monosaccharide composition was determined by ion chromatography, and the average molecular weight distribution was determined by gel chromatography.

[0033] After ultrafiltration retention, the total sugar content of DLP was 82.21 ± 1.25%, the uronic acid content was 4.13 ± 0.32%, the protein content was 3.06 ± 0.31%, and the solubility reached 87.2 ± 0.72 mg / mL, indicating that it has high purity, high solubility and is a neutral polysaccharide.

[0034] As Figure 1 shown, the monosaccharide composition of DLP after ultrafiltration retention was glucose, galactose, arabinose, xylose, rhamnose, mannose, galacturonic acid and glucuronic acid.

[0035] As Figure 2 shown, DLP after ultrafiltration retention showed a single, stacked and narrow peak, indicating that the purified DLP is a homogeneous polysaccharide component with high purity, and its average relative molecular weight is 103.1 kDa.

[0036] Experimental Example 2 Determination of the inhibition rate of macromolecular heteropolysaccharide of dried longan pulp on α-amylase The DLP sample was dissolved in PBS buffer at pH 7.4 to prepare polysaccharide solutions with different concentrations (2 - 10 mg / mL), mixed with 0.5 mL of α-amylase solution (8 U / mL), and incubated in a 37 °C water bath for 30 min. Then, 2 mL of cooked starch solution (10 mg / mL) was added to start the digestion reaction at 37 °C. The digestion solution was taken at the 10th min, and the maltose equivalent produced by the hydrolysis of α-amylase was measured at 410 nm using the PAHBAH method, thereby obtaining the inhibition rate of DLP at different concentrations on α-amylase.

[0037] As Figure 3 shown, DLP can inhibit the activity of α-amylase. When the DLP concentration is 10 mg / mL, its inhibition rate on α-amylase reaches 13.67%.

[0038] Experimental Example 3: Determination of Glucose Consumption by Macromolecular Dried Longan Pulp Heteropolysaccharide in Insulin-Resistant Cells The glucose oxidase kit was used to measure the glucose consumption. HepG2 cells were seeded into 96-well plates at a density of 5×10 5 cells / mL with DMEM complete medium containing 10% FBS. After incubation for 24 h, the medium was removed. An insulin-resistant cell model was established by inducing with 250 μM palmitic acid. After incubation for 24 h, the normal group and the model group were added with culture medium, and the DLP group was added with culture medium containing different concentrations of DLP. After continued culture for 24 h, the glucose consumption was measured using the glucose oxidase kit.

[0039] As Figure 4 shown, after intervention with 25 - 800 μg / mL DLP for 24 h, it was found that compared with the model group, the glucose consumption of the treatment group showed an upward trend. When the DLP concentration was 800 μg / mL, the glucose intake of IR-HepG2 cells increased by 38.13% compared with the model group, indicating that DLP can improve the insulin resistance state of IR-HepG2 cells.

[0040] Experimental Example 4: Determination of Glycogen Synthesis in Insulin-Resistant Cells by Macromolecular Dried Longan Pulp Heteropolysaccharide The glycogen kit was used to measure the glycogen content in the cells. HepG2 cells were seeded into 6-well plates at a density of 2.5×10 5 cells / mL with DMEM complete medium containing 10% FBS. After incubation for 24 h, the medium was removed. An insulin-resistant cell model was established by inducing with 250 μM palmitic acid. After incubation for 24 h, the normal group and the model group were added with culture medium, and the DLP group was added with culture medium containing different concentrations of DLP. After continued culture for 24 h, the glycogen synthesis in the liver was measured using the glycogen kit.

[0041] As Figure 5 shown, after treatment with different doses of DLP, compared with the model group, the intracellular glycogen synthesis in the polysaccharide treatment group increased to varying degrees. When the DLP concentration was 800 μg / mL, the hepatic glycogen synthesis in IR-HepG2 cells increased by 55.5% compared with the model group, indicating that DLP could improve the insulin resistance state of IR-HepG2 cells.

[0042] Experimental Example 5 Effect of Macromolecular Dried Longan Pulp Heteropolysaccharide on the Composition of Human Intestinal Flora First, prepare carbonate-phosphate buffer. Use an autoclave to sterilize the supplies required for the experiment (beakers, gauze, pipette tips, anaerobic culture bottles) at 121 °C for 20 min, and then dry the sterilized materials. Human fecal samples for glycolysis experiments were obtained from three healthy volunteers aged 20 - 30 years. In the past month, the three volunteers had good eating habits and no history of gastrointestinal diseases, and had not taken any antibiotics or probiotic products such as yogurt. Collect feces into a sterile tube and transfer it to an anaerobic chamber. Mix the prepared buffer with the feces of the three volunteers at a ratio of 5:1 (v:w, mL:g), and filter the mixture with gauze to obtain a fecal solution. Pipette 1 mL of the fecal solution and 4 mL of carbonate-phosphate buffer into anaerobic culture bottles containing 50 mg of Example 1, Comparative Example 1, and blank Comparative Example 2, and mix well and seal. After ensuring the anaerobic culture bottles are sealed, place them in a 37 °C water bath and incubate for glycolysis for 4, 8, 12, and 24 h respectively. Take out the anaerobic culture bottles at each time point and centrifuge at 12000 g for 10 min for 10 min to obtain the samples to be tested. Sequence data analysis was mainly carried out through the Quantitative Insights Into Microbial Ecology 2 (QIIME2) and R software package (v3.2.0). First, preliminarily screen the original downloaded data of high-throughput sequencing according to the sequence quality. The original sequences passing the initial quality screening are divided into libraries and samples according to index and Barcode information, and the barcode sequences are removed. Then use the DADA2 method to de-prime, quality filter, denoise, splice, and remove chimeras from the sequences. It no longer clusters by similarity, but only performs deduplication or clusters with 100% similarity. Each deduplicated sequence generated after DADA2 quality control is called an Amplicon Sequence Variant (ASV). Use Metastats to compare the taxonomic unit abundance results of each sample at the phylum and genus levels and display them as bar charts.

[0043] The initial in vitro flora abundance and the flora abundances at the phylum level and genus level after 24 h of fermentation in the examples and comparative examples are as Figure 6 and Figure 7 shown.

[0044] As Figure 6 shown, the dominant flora in the initial flora and each group after 24 h of fermentation were identified as Proteobacteria ( Proteobacteria ), Firmicutes ( Firmicutes ), Bacteroidetes ( Bacteroidota ), Fusobacteria ( Fusobacteriota ), and Actinobacteria ( Actinobaceriota ). After in vitro fermentation, the proportion of Bacteroidota in the intestinal flora of the DLP group (35.72%) was significantly higher than that of the blank group (14.41%), while the proportion of Firmicutes (20.05%) was lower than that of the blank group (25.76%). The total Firmicutes / Bacteroidetes (F / B) ratio of the DLP group was 0.56, significantly lower than that of the blank group (1.79). There is literature indicating that Firmicutes level reduction and Bacteroidota level elevation have an improving effect on insulin resistance and obesity symptoms induced by a high-fat diet, revealing that DLP has the effect of reducing blood sugar by regulating the composition and structure of the intestinal flora. The relative abundance of Fusobacteriota in the DLP group was 0.90%, significantly lower than that of the blank group (14.41%), indicating that DLP can reduce the growth of Fusobacteriota such pathogenic bacteria, thus avoiding diseases caused by the proliferation of Fusobacteriota .

[0045] As Figure 7 shown, at the genus level, after 24 h of fermentation, the relative abundance of Bacteroides ( Phocaeicola_A ) in the DLP group was 28.58%, significantly higher than that of the FOS group (6.25%) and the blank group (4.93%). Phocaeicola_A The genus Bacteroidota belongs to Bacteroidetes (

[0046] ), and by participating in the decomposition and fermentation processes of complex carbohydrates in the intestine, it decomposes complex sugars such as polysaccharides into short-chain fatty acids, playing a positive role in the intestinal microecology of the host. There is literature reporting that Bacteroides play an important role in improving metabolic and immune disorders in obese patients. The above results reveal the potential of DLP to reduce blood sugar by improving the intestinal flora composition and regulating the content of short-chain fatty acids.Generally speaking, the present application discloses a method for extracting a macromolecular dried longan pulp heteropolysaccharide with hypoglycemic properties. This method separates a heteropolysaccharide DLP with an average molecular weight of Mw = 103.1 kDa retained by ultrafiltration from dried longan through processes such as hot water extraction, dialysis, and ultrafiltration retention. Through in vitro starch digestive enzyme inhibition experiments, insulin-resistant cell models, and in vitro simulated human fecal fermentation, it was found that DLP can inhibit the activity of α-amylase, improve the glucose consumption and hepatic glycogen synthesis in insulin-resistant cells, and by improving the composition of the human gut microbiota, it can better promote the proliferation of the beneficial bacterium Bacteroidetes and inhibit the harmful bacterium Fusobacteriota compared with commercially available fructooligosaccharides, becoming a potential hypoglycemic active ingredient.

[0047] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the claimed invention.

Claims

1. A preparation method of a macromolecular dried longan pulp heteropolysaccharide with hypoglycemic properties, characterized in that , The preparation method includes drying longan pulp, homogenizing the dried pulp, adding distilled water, performing hot water extraction, and filtering through gauze, and separating the dried longan pulp heteropolysaccharide with a molecular weight greater than 100 kDa and hypoglycemic properties from the dried longan pulp through processes such as dialysis and ultrafiltration retention.

2. The preparation method of a macromolecular dried longan pulp heteropolysaccharide with hypoglycemic properties as described in claim 1, characterized in that , The preparation method includes the following steps: S1. Dry the longan pulp to obtain dried longan pulp, homogenize the longan pulp, add the slurry to distilled water for hot water extraction, concentrate and then centrifuge, and dialyze and centrifuge the supernatant to obtain the crude dried longan pulp polysaccharide; S2. Use an ultrafiltration system device to perform ultrafiltration retention on the obtained dried longan pulp polysaccharide, concentrate and freeze-dry to obtain the macromolecular dried longan pulp heteropolysaccharide with hypoglycemic properties.

3. The preparation method of a macromolecular dried longan pulp heteropolysaccharide with hypoglycemic properties as described in claim 1, characterized in that , In S1, the longan pulp is dried to a moisture content of 18%; 4600 mL of distilled water is added, and hot water extraction is performed at 80 °C for 3 h; it is concentrated under reduced pressure to a volume of 500 mL; centrifugation is carried out at 4 °C under the conditions of 10000 g for 10 min to obtain the supernatant; the supernatant is dialyzed using a dialysis bag with a molecular weight of 6000 Da in a 4 °C refrigerator for 3 days, and ultrapure water is replaced every 8 h.

4. The preparation method of a macromolecular dried longan pulp heteropolysaccharide with hypoglycemic properties as described in claim 1, characterized in that , In S1, the longan pulp is dried to a moisture content of 18%; 4600 mL of distilled water is added, and hot water extraction is performed at 80 °C for 3 h; it is concentrated under reduced pressure to a volume of 500 mL; centrifugation is carried out at 4 °C under the conditions of 10000 g for 10 min to obtain the supernatant; the supernatant is dialyzed using a dialysis bag with a molecular weight of 6000 Da in a 4 °C refrigerator for 3 days, and ultrapure water is replaced every 8 h.

5. The preparation method of a macromolecular dried longan pulp heteropolysaccharide with hypoglycemic properties as described in claim 1, characterized in that , In S2, an ultrafiltration retention system device is used to pass 1000 mL of the dried longan pulp polysaccharide solution through a filter membrane with a molecular weight Mw of 100 kDa, and after retaining 200 mL of the solution, a dried longan pulp heteropolysaccharide solution with a molecular weight greater than 100 kDa is obtained.

6. The macromolecular dried longan pulp heteropolysaccharide with hypoglycemic properties according to claim 5, characterized in that , The longan pulp heteropolysaccharide has high solubility and high purity. Its total sugar content is 82.21 ± 1.25%, the uronic acid content is 4.13 ± 0.32%, the protein content is 3.06 ± 0.31%, and the solubility reaches 87.2 ± 0.72 mg / mL.

7. A macromolecular dried longan pulp heteropolysaccharide with hypoglycemic properties, characterized in that , The heteropolysaccharide is composed of various monosaccharides connected by glycosidic bonds, and its components include glucose, galactose, arabinose, xylose, rhamnose, mannose, as well as galacturonic acid and glucuronic acid.

8. The macromolecular dried longan pulp heteropolysaccharide with hypoglycemic properties according to claim 7, characterized in that , The molar ratio of the glucose, galactose, arabinose, xylose, rhamnose, mannose, galacturonic acid, and glucuronic acid is 34.2:27.3:20.6:4.2:3.0:2.3:6.5:1.

3.

9. Use of the dried longan pulp heteropolysaccharide combined with hot water extraction method and ultrafiltration retention in the preparation of substances for inhibiting α-amylase, improving the glucose consumption and hepatic glycogen synthesis amount of insulin-resistant cells, regulating the human intestinal flora, and preparing substances with hypoglycemic and / or improving intestinal flora disorder functions.

10. A food or a drug, characterized in that, The preparation method whose composition contains the macromolecular dried longan pulp heteropolysaccharide with hypoglycemic properties as described in any one of claims 1-5.

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