A polysaccharide of gold bell and an extraction method and application thereof

Abstract

This invention provides a polysaccharide from *Melia azedarach*, its extraction method, and its applications, belonging to the field of polysaccharide extraction technology. The *Melia azedarach* polysaccharide includes at least one of *Melia azedarach* polysaccharide 1 and *Melia azedarach* polysaccharide 2. *Melia azedarach* polysaccharide 1 comprises the polysaccharide molecule represented by formula (I), and *Melia azedarach* polysaccharide 2 comprises the polysaccharide molecule represented by formula (II). This invention also provides a method for extracting this *Melia azedarach* polysaccharide. This *Melia azedarach* polysaccharide exhibits good effects in fat binding, bile acid binding, cholesterol binding, and lipase inhibition, and has broad application prospects in the preparation of lipid-lowering products.

Description

Technical Field

[0001] This invention belongs to the field of polysaccharide extraction technology, and relates to a polysaccharide from the fruit of the plant *Melastoma candida*, its extraction method, and its application. Background Technology

[0002] Lipid metabolism disorders are abnormal concentrations of lipids and their metabolites in the blood and / or other tissues and organs caused by various factors. These factors can be congenital or acquired. Lipid metabolism disorders, especially those involving slow or poor metabolism of excess lipids, can lead to symptoms such as hyperlipoproteinemia, obesity, and fatty liver disease, which are key culprits in endangering human health.

[0003] The following pathways can improve lipid metabolism disorders and their associated symptoms such as hyperlipidemia, obesity, and fatty liver:

[0004] (1) Inhibits lipase activity.

[0005] (2) It binds to bile acids in the digestive tract to regulate lipid absorption and metabolism.

[0006] (3) It binds to cholesterol in the digestive tract to regulate lipid absorption and metabolism.

[0007] (4) Regulate the expression of key enzyme genes in the lipid metabolism pathway.

[0008] Bitter melon, also known as balsam pear or mountain bitter melon, with the Latin name *Momordica charantia* Linn. var. *abbreviata* Ser., is a cultivated variety of bitter melon belonging to the genus *Momordica* in the Cucurbitaceae family. It is an annual or perennial vine native to the Jiangnan region of China, growing in tropical and temperate regions. When ripe, the fruit gradually changes color from green to orange, with blood-red flesh and a sweet taste, and can be eaten as a fruit. Modern medical research shows that bitter melon and its extracts have significant hypoglycemic, antitumor, antiviral, and antibacterial effects. Traditional Chinese medicine classics record that bitter melon is "bitter and cold in nature. It enters the heart, spleen, and lung meridians. It relieves summer heat, clears away heat, brightens the eyes, and detoxifies. It is used to treat summer heat and thirst, diabetes, red and painful eyes, dysentery, carbuncles, and boils."

[0009] In their article "Regulatory Effects of Bitter Melon Polysaccharides and Saponins on Lipid Metabolism in *C. elegans*", Jia Donghao et al. (Grain and Food Industry, 30, 5, 2023, pp. 28-32) disclosed a method for extracting bitter melon polysaccharides and saponins. The method for extracting bitter melon polysaccharides involved refluxing freeze-dried bitter melon powder in 95% ethanol for 2 hours, extracting the residue three times with hot water at 90°C, collecting the filtrate, concentrating it, removing protein using the Sevage method, and then obtaining bitter melon polysaccharides through alcohol precipitation, dialysis, and freeze-drying. The bitter melon polysaccharides extracted by this method could reduce the triglyceride content in *C. elegans*, however, its effect on reducing the amount of fat deposited in the nematode was limited.

[0010] Patent CN106589149B discloses a method for extracting bitter melon polysaccharides, along with the resulting product and its applications. The method involves adding bitter melon powder to water at a ratio of 1:35-45 (material to liquid) at 90-100℃, adjusting the pH to 7.5-8.5, followed by ultrasonic extraction. Then, 3%-10% (by weight of the substrate) of α-amylase is added to the mixture, and the reaction is carried out at 35-40℃ for 15-25 minutes. The entire system is then transferred to water at 90-100℃ for 4-6 minutes, followed by the addition of trichloroacetic acid, filtration, and concentration to obtain a concentrated solution, which is then washed and dried. The resulting bitter melon polysaccharides exhibit high bioactivity and purity, with a high extraction rate throughout the process. However, this technology does not disclose a polysaccharide substance with lipid-lowering effects.

[0011] Patent CN108586560B discloses a one-step aqueous two-phase extraction method for bitter melon saponins and polysaccharides with hypoglycemic activity, comprising the following steps: Dry bitter melon powder is mixed with an isopropanol / (NH4)2SO4 aqueous two-phase system, and extracted using ultrasonic-microwave synergistic extraction. The upper and lower phases are then separated. The upper phase is a crude extract of bitter melon saponins, which is rotary evaporated until no alcohol odor is detected, yielding a bitter melon saponin extract. This extract is then purified by static adsorption using AB-8 macroporous resin to obtain a refined extract of bitter melon saponins, which is freeze-dried to obtain the final bitter melon saponin product. The lower phase is a crude extract of bitter melon polysaccharides, which is precipitated with anhydrous ethanol, washed with acetone, and dialyzed to obtain a refined extract of bitter melon polysaccharides, which is then freeze-dried to obtain the final bitter melon polysaccharide product. However, this technology does not disclose a polysaccharide substance with hypoglycemic activity.

[0012] In summary, existing technologies cannot provide a new type of *Gynostemma pentaphyllum* polysaccharide with better lipid-lowering effects. Summary of the Invention

[0013] In view of this, and in response to the problem that existing technologies cannot provide a new polysaccharide from *Gynostemma pentaphyllum* with better lipid-lowering effects, the purpose of this invention is to provide a polysaccharide from *Gynostemma pentaphyllum*, its extraction method, and its application.

[0014] To achieve the above-mentioned objectives, in one aspect, the present invention provides a *Melia azedarach* polysaccharide, comprising at least one of *Melia azedarach* polysaccharide 1 and *Melia azedarach* polysaccharide 2, wherein *Melia azedarach* polysaccharide 1 comprises a polysaccharide molecule represented by formula (I):

[0015]

[0016] The golden bell polysaccharide 2 comprises the polysaccharide molecule shown in formula (II):

[0017]

[0018] Preferably, the total sugar content of the golden bell polysaccharide 1 is 82.82% ± 1.29%.

[0019] More preferably, the total protein content of the *Gynostemma pentaphyllum* polysaccharide 1 is 1.67% ± 0.04%.

[0020] Preferably, the golden bell polysaccharide 1 comprises the following structural units: galacturonic acid, galactose, rhamnose, and arabinose.

[0021] More preferably, the *Gynostemma pentaphyllum* polysaccharide 1 mainly comprises the following structural units: galacturonic acid, galactose, rhamnose, and arabinose.

[0022] More preferably, the golden bell polysaccharide 1 further includes the following structural units: xylose, glucuronic acid and fucose.

[0023] Further preferably, and as an example of the present invention, the *Gynostemma pentaphyllum* polysaccharide 1 comprises the following structural units: galacturonic acid, galactose, rhamnose, arabinose, xylose, glucuronic acid, and fucose, and the molar ratio of galacturonic acid:galactose:rhamnose:arabinose:xylose:glucuronic acid:fucose is 61.85:17.43:12.67:14.28:3.36:1.76:1.00.

[0024] Preferably, the glycosidic bonds of the golden bell polysaccharide 1 include the following types: →4)-GalpA-(1→、→5)-Araf-(1→、→4)-GalpA-(3→、→2)-Rhap ...

[0025] More preferably, the glycosidic bonds of the Golden Bell Polysaccharide 1 include the following types: →4)-GalpA-(1→、→5)-Araf-(1→、→4)-GalpA-(3→、→2)-Rhap ...

[0026] Preferably, the total sugar content of the *Gynostemma pentaphyllum* polysaccharide 2 is 84.97% ± 2.34%.

[0027] More preferably, the total protein content of the *Gynostemma pentaphyllum* polysaccharide 2 is 0.21% ± 0.01%.

[0028] Preferably, the golden bell polysaccharide 2 comprises the following structural units: galacturonic acid, galactose, rhamnose, and arabinose.

[0029] More preferably, the golden bell polysaccharide 2 mainly comprises the following structural units: galacturonic acid, galactose, rhamnose and arabinose.

[0030] More preferably, the golden bell polysaccharide 2 further includes the following structural units: xylose, glucose, glucuronic acid and fucose.

[0031] Further preferably, and as an example of the present invention, the *Gynostemma pentaphyllum* polysaccharide 2 comprises the following structural units: galacturonic acid, galactose, rhamnose, arabinose, xylose, glucose, glucuronic acid, and fucose, wherein the molar ratio of galacturonic acid:galactose:rhamnose:arabinose:xylose:glucose:glucuronic acid:fucose is 15.63:4.46:6.05:5.00:3.76:2.19:1.44:1.00.

[0032] Preferably, the glycosidic bonds of the golden bell polysaccharide 2 include the following types: →4)-GalpA-(1→、→5)-Araf-(1→、→3)-Galp-(1→、→3)-Araf-t.

[0033] More preferably, the glycosidic bonds of the Golden Bell Polysaccharide 1 include the following types: →4)-GalpA-(1→、→5)-Araf-(1→、→3)-Galp-(1→、→3)-Araf-t, and the molar ratio of the above four glycosidic bonds is 7.37:1.13:1.05:1.00.

[0034] On the other hand, the present invention provides a method for extracting the above-mentioned polysaccharide from *Melastoma candida*, comprising the following steps:

[0035] S1. Mix the pericarp of the golden bell fruit with water, extract, and concentrate to obtain an aqueous extract;

[0036] S2. Add ethanol to the aqueous extract obtained in step S1, and precipitate with alcohol to obtain the first precipitate and supernatant.

[0037] S3. Add ethanol to the supernatant obtained in step S2 and precipitate to obtain a second precipitate.

[0038] S4. Purify and dialyze the first precipitate obtained in step S2 to obtain the first polysaccharide;

[0039] S5. Purify and dialyze the second precipitate obtained in step S3 to obtain the second polysaccharide;

[0040] S6. Purify the first polysaccharide obtained in step S4, collect polysaccharides with a molecular weight of 30-34kDa, and obtain Jinlingzi polysaccharide 1;

[0041] S7. Purify the second polysaccharide obtained in step S5, collect polysaccharides with a molecular weight of 5.0-5.5 kDa, and obtain Jinlingzi polysaccharide 2;

[0042] In step S2, the volume ratio of the aqueous extract to the ethanol is 1:0.5-2; in step S3, the volume ratio of the supernatant to the ethanol is 1:0.5-2.

[0043] Preferably, and as an example of the present invention, in step S2, the volume ratio of the aqueous extract to the ethanol is 1:1; in step S3, the volume ratio of the supernatant to the ethanol is 1:1.

[0044] Preferably, in step S1, the pericarp of the golden bell fruit is fresh.

[0045] Preferably, in step S1, the ratio of the mass of the golden bell fruit peel to the volume of the water is 1g:5-30mL.

[0046] More preferably, in step S1, the ratio of the mass of the golden bell fruit peel to the volume of the water is 1g:10-20mL.

[0047] More preferably, in step S1, the ratio of the mass of the golden bell fruit peel to the volume of the water is 1g:16mL.

[0048] Preferably, in step S1, the mixing with water is homogenization in water.

[0049] More preferably, the homogenization in water specifically refers to the homogenization being performed using an IKA T18 digitalULTRA-TURRAX digital display high-speed disperser, with homogenization conditions of 15000 rpm and 15 min.

[0050] Preferably, in step S1, the extraction is ultrasound-assisted extraction.

[0051] More preferably, the ultrasonic-assisted extraction time is 10-20 min and the power is 200-400 W.

[0052] More preferably, the ultrasonic-assisted extraction time is 16 minutes and the power is 312W.

[0053] In a preferred embodiment of the present invention, in step S1, the mass ratio of the *Melia azedarach* pericarp to the volume of water is 1 g: 16 mL, the extraction is ultrasound-assisted extraction, the ultrasound time is 16 min, and the ultrasound power is 312 W. The combination of the above-mentioned mass ratio of *Melia azedarach* pericarp to water, ultrasound time, and ultrasound power is obtained through single-factor experiments and response surface methodology, with the crude polysaccharide extraction rate as the target parameter under these conditions. The crude polysaccharide extraction rate refers to the percentage of the mass of the precipitate (after drying) obtained by adding 3 times the volume of ethanol to the aqueous extract obtained in step S1 for alcohol precipitation. Experiments show that in step S1, under the conditions of a mass ratio of *Melia azedarach* pericarp to water of 1 g: 16 mL, ultrasound-assisted extraction, an ultrasound time of 16 min, and an ultrasound power of 312 W, the crude polysaccharide extraction rate is the highest, reaching 8.33% ± 0.13%.

[0054] Preferably, in step S2, solid-liquid separation is performed after alcohol precipitation.

[0055] More preferably, the solid-liquid separation is filtration.

[0056] Preferably, in step S3, solid-liquid separation is performed after alcohol precipitation.

[0057] More preferably, the solid-liquid separation is filtration.

[0058] Preferably, in step S4, the purification process involves removing proteins and pigments.

[0059] Preferably, in step S5, the purification process involves removing proteins and pigments.

[0060] Preferably, in step S6, the purification is performed by anion exchange chromatography and dextran gel chromatography.

[0061] More preferably, in step S6, the purification involves sequentially performing anion exchange chromatography and dextran gel chromatography.

[0062] Preferably, in step S7, the purification is performed by anion exchange chromatography and dextran gel chromatography.

[0063] More preferably, in step S7, the purification involves sequentially performing anion exchange chromatography and dextran gel chromatography.

[0064] Furthermore, this invention provides the application of the above-mentioned *Gynostemma pentaphyllum* polysaccharide and the above-mentioned extraction method in the preparation of lipid-lowering products.

[0065] In another aspect, the present invention provides a lipid-lowering product, comprising the above-mentioned *Gynostemma pentaphyllum* polysaccharide and / or *Gynostemma pentaphyllum* polysaccharide extracted by the above-mentioned *Gynostemma pentaphyllum* polysaccharide extraction method.

[0066] Compared with the prior art, the present invention has the following beneficial effects:

[0067] (1) This invention provides a novel method for extracting polysaccharides from *Melastoma candida*, yielding a novel polysaccharide. Structural analysis shows that the main component of this polysaccharide is a novel polysaccharide compound.

[0068] (2) Experiments show that the polysaccharide extracted from the golden bell fruit in this invention has the ability to bind fat, bind bile acids, bind cholesterol and inhibit lipase.

[0069] (3) The extraction method provided by the present invention is simple and easy to implement, and has a significant anti-lipid effect. It has broad application prospects in the preparation of anti-lipid products. Attached Figure Description

[0070] Figure 1 This is a photograph of the raw material used in this invention, namely, the golden bell fruit, where A is the pericarp of the golden bell fruit and B is the seed of the golden bell fruit.

[0071] Figure 2a The nuclear magnetic resonance (NMR) of the *Gynostemma pentaphyllum* polysaccharide 1 prepared in Example 1 is shown. 1 H spectrum.

[0072] Figure 2b The nuclear magnetic resonance (NMR) of the *Gynostemma pentaphyllum* polysaccharide 1 prepared in Example 1 is shown. 13 C-spectrum.

[0073] Figure 2c This is the heteronuclear single quantum relation (HSQC) spectrum of the *Gynostemma pentaphyllum* polysaccharide 1 prepared in Example 1.

[0074] Figure 2d The image shows the correlation magnetic resonance spectrum (COSY) of the polysaccharide 1 prepared in Example 1, where the coordinates of A are {4.93, 3.48}, the coordinates of B are {5.04, 4.05}, the coordinates of D are {5.04, 3.93}, the coordinates of E are {4.96, 3.77}, and all of the above coordinates are {f2, f1} coordinates.

[0075] Figure 2e It is the golden bell polysaccharide 1 prepared in Example 1. 1 The heteronuclear multicarbon correlation spectrum (HMBC) of H.

[0076] Figure 3a The nuclear magnetic resonance (NMR) of the *Gynostemma pentaphyllum* polysaccharide 2 prepared in Example 1 is shown. 1 H spectrum.

[0077] Figure 3b The nuclear magnetic resonance (NMR) of the *Gynostemma pentaphyllum* polysaccharide 2 prepared in Example 1 is shown. 13 C-spectrum.

[0078] Figure 3cThis is the heteronuclear single quantum relation (HSQC) spectrum of the *Gynostemma pentaphyllum* polysaccharide 2 prepared in Example 1.

[0079] Figure 3d The image shows the correlation magnetic resonance spectrum (COSY) of the polysaccharide 2 prepared in Example 1, where the coordinates of A are {4.98, 3.69}, the coordinates of B are {5.13, 3.92}, the coordinates of D are {5.00, 3.69}, the coordinates of E are {5.00, 4.05}, and all of the above coordinates are {f2, f1} coordinates.

[0080] Figure 3e It is the golden bell polysaccharide 2 prepared in Example 1. 1 The heteronuclear multicarbon correlation spectrum (HMBC) of H. Detailed Implementation

[0081] The following non-limiting embodiments are intended to enable those skilled in the art to gain a more comprehensive understanding of the present invention, but do not limit the invention in any way. The following description is merely an exemplary illustration of the scope of protection of the present invention, and those skilled in the art can make various changes and modifications to the invention based on the disclosed content, which should also fall within the scope of protection of the present invention.

[0082] The present invention will be further described below by way of specific embodiments. Unless otherwise specified, all chemical reagents used in the embodiments of the present invention were obtained through conventional commercial means. Unless otherwise specified, all contents mentioned below are mass contents. Unless otherwise specified, it is understood that the process was carried out at room temperature.

[0083] The carboxymethyl cellulose used in the effect evaluation section of this invention was purchased from Sigma-Aldrich.

[0084] The golden bells used in this invention are all fresh golden bell fruits, such as Figure 1 As shown. This invention extracts polysaccharides from *Melia azedarach* using the pericarp of *Melia azedarach*, i.e. Figure 1 Part A of the text.

[0085] Example 1

[0086] Extraction of Polysaccharide 1 and Polysaccharide 2 from Melia toosendan.

[0087] S1. Take the pericarp of *Melia azedarach*, homogenize it in water, and then perform ultrasound-assisted extraction. The mass ratio of pericarp to water is 1g:16mL. The ultrasound-assisted extraction time is 16min, the ultrasound power is 312W, and the extract is concentrated to obtain the aqueous extract.

[0088] Specifically, the homogenization was performed using an IKA T18 digital ULTRA-TURRAX high-speed disperser with a digital display, and the homogenization conditions were 15,000 rpm for 15 minutes.

[0089] The concentration process specifically involves centrifugation (at 20°C and 10,000 rpm for 15 minutes), taking the supernatant, and then concentrating it by rotary evaporation (at 50°C and <0.1 MPa) to one-fifth of its original volume.

[0090] S2. Add anhydrous ethanol to the aqueous extract obtained in step S1 at a volume ratio of 1:1 to perform alcohol precipitation. Filter and collect the precipitate and supernatant separately. This precipitate is the first precipitate.

[0091] S3. Add anhydrous ethanol to the supernatant obtained in step S2 at a volume ratio of 1:1 to perform alcohol precipitation. Filter and collect the precipitate, which is the second precipitate.

[0092] S4. Remove the protein and pigment from the first precipitate obtained in step S2, dialyze it, freeze-dry it, and obtain the first polysaccharide.

[0093] S5. Remove the protein and pigment from the second precipitate obtained in step S3, dialyze it, and freeze-dry it to obtain the second polysaccharide.

[0094] The specific methods for removing protein and pigment, dialysis, and lyophilization in steps S4 and S5 are as follows:

[0095] After redissolving the precipitate in deionized water, the Sevage method was used to remove proteins and pigments. This involved mixing the polysaccharide solution with Sevage reagent [chloroform: n-butanol = 3:1 (V / V)] at a 3:1 ratio, shaking, centrifuging, and collecting the upper aqueous phase. This process was repeated until no significant protein residue remained at the interface between the two phases. The solution was then concentrated by rotary evaporation to remove any remaining Sevage reagent. The polysaccharide solution was transferred to a 3500 Da dialysis bag and dialyzed in deionized water at 4℃ for 48 h (water changed every 4 h). After vacuum freeze-drying, two *Ipomoea aquatica* polysaccharide fractions were obtained. The polysaccharide yield was calculated after weighing. The freeze-drying conditions were: freeze dryer cold trap temperature -50℃, vacuum degree 1-10 Pa, and sample freeze-drying time 36 h, or ensuring the sample reached a completely dry state.

[0096] S6. The first polysaccharide was subjected to anion exchange chromatography and dextran gel chromatography. The fraction with a molecular weight of 30-34 kDa was collected, which was identified as *Gynostemma pentaphyllum* polysaccharide 1.

[0097] S7. The second polysaccharide was subjected to anion exchange chromatography and dextran gel chromatography. The fraction with a molecular weight of 5.0-5.5 kDa was collected, which was identified as *Lysimachia christinae* polysaccharide 2.

[0098] In steps S6 and S7, the specific steps of the anion exchange chromatography are as follows:

[0099] Accurately weigh 100 mg of either the first or second polysaccharide and prepare a 20 mg / mL solution with ultrapure water. Filter the solution through a 0.45 μm aqueous filter membrane. Load the solution onto a DEAE Sepharose Fast Flow ion exchange chromatography column (35 mm × 300 mm) using a disposable syringe. Elute sequentially with 200 mL of ultrapure water, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, and 0.5 mol / L NaCl solutions, collecting the eluents using a fraction collector. Maintain the elution flow rate at 1.0 mL / min, collecting one tube every 5 min, for a total of 40 tubes of each concentration. Monitor the polysaccharide content in each tube using the phenol-sulfuric acid method. Plot the elution curves based on the absorbance of the eluents at 490 nm using a microplate reader. Four elution peaks were observed after elution of the first polysaccharide, and four elution peaks were observed after elution of the second polysaccharide. The number of elution tubes corresponding to the elution peaks was collected according to the elution curve. The fractions were concentrated by rotary evaporation at 50°C, transferred to a 3500Da dialysis bag, and dialyzed at 4°C for 48 hours (with water changed every 4 hours). The fractions were then obtained by vacuum freeze drying.

[0100] The first polysaccharide was separated using a DEAE Sepharose Fast Flow ion exchange chromatography column, yielding four elution peaks corresponding to the ultrapure water eluent, 0.1 mol / L NaCl eluent, 0.3 mol / L NaCl eluent, and 0.4 mol / L NaCl eluent, respectively. After screening, the 0.3 mol / L NaCl eluent with the largest peak area was selected for further accumulation and purification, yielding the fraction obtained from the separation of the first polysaccharide. The second polysaccharide was also separated using a DEAE Sepharose Fast Flow ion exchange chromatography column, yielding four elution peaks again, corresponding to the ultrapure water eluent, 0.1 mol / L NaCl eluent, 0.2 mol / L NaCl eluent, and 0.4 mol / L NaCl eluent, respectively. After screening, the 0.2 mol / L NaCl eluent with the largest peak area was selected for further accumulation and purification, yielding the fraction obtained from the separation of the second polysaccharide.

[0101] In steps S6 and S7, the dextran gel chromatography steps are as follows:

[0102] The fraction obtained from the separation of the first polysaccharide was purified by elution with 0.3 mol / L NaCl solution, yielding a single symmetrical peak. After dialyzing and lyophilization, it yielded *Lysimachia christinae* polysaccharide 1. The fraction obtained from the separation of the second polysaccharide was purified by elution with 0.2 mol / L NaCl solution, yielding a single symmetrical peak. After dialyzing and lyophilization, it yielded *Lysimachia christinae* polysaccharide 2.

[0103] The specific steps are as follows:

[0104] The fractions obtained from the separation of the first and second polysaccharides were purified using Sephadex G-100 and Sephadex G-75 dextran gel chromatography, respectively. Before loading, the fractions obtained from the separation of the first and second polysaccharides were loaded onto the column using NaCl solution (0.3 mol / L sodium chloride solution for the first polysaccharide and 0.2 mol / L sodium chloride solution for the second polysaccharide) and equilibrated at a flow rate of 0.4 mL / min for 12 h. 30 mg of the fractions obtained from the separation of the first and second polysaccharides were weighed and dissolved in 3 mL of ultrapure water (the fraction obtained from the first polysaccharide was vortexed for mixing). The solution was then filtered through a 0.45 μm aqueous filter membrane and loaded onto a dextran gel chromatography column (16 mm × 500 mm) using a disposable syringe. After loading, the column was allowed to stand for equilibration for 10 min, and then eluted with NaCl solution of the corresponding concentration at a flow rate of 0.4 mL / min, collecting one tube every 5 min. The polysaccharide content in each eluent tube was monitored using the phenol-sulfuric acid method, and elution curves were plotted based on the absorbance of the eluent at 490 nm using a microplate reader. The number of eluent tubes corresponding to each elution peak was collected according to the elution curves, concentrated by rotary evaporation at 50 °C, transferred to a 3500 Da dialysis bag, and dialyzed at 4 °C for 48 h (with water changed every 4 h). The resulting products were then freeze-dried under vacuum to obtain *Lysimachia christinae* polysaccharide 1 and polysaccharide 2, respectively.

[0105] The total sugar and protein content of the obtained *Melia azedarach* polysaccharide 1 and polysaccharide 2 were determined. The determination methods are as follows:

[0106] Total sugar content determination: The polysaccharide content was determined using the phenol-sulfuric acid method described in the reference "Colorimetric method for determination of sugars and related substances" (Dubois M, Gilles KA, Hamilton JK, et al. 1956, 28:350-356). A standard curve was plotted: y = 0.9278x + 0.0589 (r). 2 =0.9994), where x is the concentration of galacturonic acid standard in mg / mL and y is the absorbance value.

[0107] Protein content detection: The protein content was detected using a commercially available BCA protein content detection kit (brand: Shanghai Solarbio).

[0108] The tests showed that the total sugar content of *Gynostemma pentaphyllum* polysaccharide 1 was 82.82% ± 1.29%, and the total protein content was 1.67% ± 0.04%; the total sugar content of *Gynostemma pentaphyllum* polysaccharide 2 was 84.97% ± 2.34%, and the total protein content was 0.21% ± 0.01%.

[0109] Example 2

[0110] Extraction of crude polysaccharides from the pericarp of *Gynostemma pentaphyllum*.

[0111] S1. Take fresh *Melia azedarach* pericarp, homogenize it in water, and then perform ultrasound-assisted extraction. The mass ratio of *Melia azedarach* pericarp to water is 1 g: 16 mL. The ultrasound-assisted extraction time is 16 min, and the ultrasound power is 312 W. Concentrate to obtain the aqueous extract.

[0112] Specifically, the homogenization was performed using an IKA T18 digital ULTRA-TURRAX high-speed disperser with a digital display, and the homogenization conditions were 15,000 rpm for 15 minutes.

[0113] The concentration process specifically involves centrifugation (at 20°C and 10,000 rpm for 15 minutes), taking the supernatant, and then concentrating it by rotary evaporation (at 50°C and <0.1 MPa) to one-fifth of its original volume.

[0114] S2. Add anhydrous ethanol to the aqueous extract obtained in step S1 at a volume ratio of 1:3 to perform alcohol precipitation. Filter, collect the precipitate, and freeze-dry to obtain crude polysaccharide.

[0115] The crude polysaccharide extraction rate is the percentage of crude polysaccharide in the pericarp of *Cynanchum paniculatum*. Under these conditions, the crude polysaccharide extraction rate can reach 8.33% ± 0.13%.

[0116] Example 3

[0117] Compared with Example 2, in step S1, the mass ratio of the pericarp of the golden bell fruit to the volume ratio of water was changed to 1g:10mL, while all other steps remained the same.

[0118] Example 4

[0119] Compared with Example 2, in step S1, the mass ratio of the pericarp of the golden bell fruit to the volume ratio of water was changed to 1g:20mL, while all other steps remained the same.

[0120] Example 5

[0121] Compared with Example 2, in step S1, the time for ultrasonic-assisted extraction was changed to 10 min, while the rest remained the same.

[0122] Example 6

[0123] Compared with Example 2, in step S1, the time for ultrasonic-assisted extraction was changed to 20 min, while the rest remained the same.

[0124] Example 7

[0125] Compared with Example 2, in step S1, the ultrasonic power is changed to 200W, and the rest are the same.

[0126] Example 8

[0127] Compared with Example 2, in step S1, the ultrasonic power is changed to 400W, and the rest are the same.

[0128] Comparative Example 1

[0129] Compared with Example 2, in step S1, the ultrasound-assisted time is changed to 30 min, the ultrasound power is changed to 450 W, and the rest are the same.

[0130] The extraction rates of crude polysaccharides from the pericarp of *Gnaphalium affine* in Examples 2-8 and Comparative Example 1 are shown in the table below.

[0131]

[0132]

[0133] Comparative Example 2

[0134] The preparation steps of the polysaccharide from *Melia azedarach* are as follows:

[0135] The pericarp of the fruit of the golden bell fruit was freeze-dried and ground into a freeze-dried powder. The freeze-dried powder was refluxed in 95% ethanol for 2 hours, and the filter residue was extracted three times with hot water at 90°C. The filtrate was collected, concentrated, and protein was removed using the Sevage method. After precipitation with 90% ethanol, dialysis, and freeze-drying, the golden bell fruit polysaccharide was obtained.

[0136] Comparative Example 3

[0137] The method of Example 1 in patent CN108586560B was used to prepare Jinlingzi polysaccharide, except that the raw material was changed from dried bitter melon powder to freeze-dried Jinlingzi peel powder of equal mass, and all other aspects were the same.

[0138] Example of determination: Polysaccharide structure determination

[0139] 1. Determination of monosaccharide composition

[0140] The determination method is based on the article "Food Chem, 2018, 249:127-135", as detailed below.

[0141] Weigh appropriate amounts of *Gynostemma pentaphyllum* polysaccharide 1 / 2, add 1 mL of 2 mol / L trifluoroacetic acid solution, and heat at 121℃ for 2 hours. Purge with nitrogen and dry. Wash with 99.99% methanol, then dry again, repeating the methanol washing 2-3 times. Dissolve in sterile water and transfer to a chromatographic bottle for analysis. Take an appropriate amount of polysaccharide solution, concentrate by rotation or dry with nitrogen. Add 1 mL of 2 mol / L trifluoroacetic acid solution, and heat at 121℃ for 2 hours. Purge with nitrogen and dry. Wash with 99.99% methanol, then dry again, repeating the methanol washing 2-3 times. Dissolve in pure water and transfer to a chromatographic bottle for later use.

[0142] Ion chromatography injection and analysis conditions: Detection was performed using a Thermo ICS 5000+ ion chromatography system (ICS 5000+, Thermo Fisher Scientific, USA), equipped with a Dionex... TM CarboPac TM PA20 (150mm × 3.0mm, 10μm) HPLC column, injection volume 5μL. Mobile phase A (H2O), mobile phase B (0.1mol / L NaOH aqueous solution), mobile phase C (0.1mol / L NaOH and 0.2mol / L sodium acetate aqueous solution), flow rate 0.5mL / min; column temperature 30℃; elution gradient: 0 min mobile phase A / mobile phase B / mobile phase C (95:5:0, v / v), 26 min mobile phase A / mobile phase B / mobile phase C (85:5:10, v / v), 42 min... Mobile phase A / Mobile phase B / Mobile phase C (85:5:10, v / v), 42.1 min Mobile phase A / Mobile phase B / Mobile phase C (60:0:40, v / v), 52 min Mobile phase A / Mobile phase B / Mobile phase C (60:40:0, v / v), 52.1 min Mobile phase A / Mobile phase B / Mobile phase C (95:5:0, v / v), 60 min Mobile phase A / Mobile phase B / Mobile phase C (95:5:0, v / v).

[0143] The monosaccharide components were analyzed and detected using an electrochemical detector.

[0144] The monosaccharide composition of *Melastoma candida* polysaccharide 1 and *Melastoma candida* polysaccharide 2 prepared in Example 1 was detected using the above method, and the results are as follows:

[0145] The monosaccharide compositions of Melia toosendan polysaccharide 1 and Melia toosendan polysaccharide 2 are shown in the table below:

[0146] Monosaccharide composition (molar ratio) Golden Bell Fruit Polysaccharide 1 Golden Bell Polysaccharide 2 Rhamnose 12.67 6.05 Glucuronic acid 1.76 1.44 Galacturonic acid 61.85 15.63 glucose Not detected 2.19 Galactose 17.43 4.46 Xylose 3.36 3.76 Arabic sugar 14.28 5.00 Fucose 1.00 1.00

[0147] As shown in the table above, after separation and purification, the monosaccharide composition of *Gynostemma pentaphyllum* polysaccharide 1 includes galacturonic acid (Gal-A), galactose (Gal), rhamnose (Rha), and arabinose (Ara), with small amounts of xylose (Xyl), glucuronic acid (Glc-A), and fucose (Fuc). The molar ratio of each monosaccharide in *Gynostemma pentaphyllum* polysaccharide 1 is Rha:Glc-A:Gal-A:Gal:Xyl:Ara:Fuc = 12.78:1.76:61.85:17.43:3.36:14.28:1.00. The monosaccharide composition of *Gynostemma pentaphyllum* polysaccharide 2 includes galacturonic acid (Gal-A), galactose (Gal), rhamnose (Rha), and arabinose (Ara), with small amounts of xylose (Xyl), glucose (Glc), glucuronic acid (Glc-A), and fucose (Fuc). The molar ratio of monosaccharides in Golden Bell Polysaccharide 2 is Rha:Glc-A:Gal-A:Glc:Gal:Xyl:Ara:Fuc=6.05:1.44:15.63:2.19:4.46:3.76:5.00:1.00.

[0148] 2. Methylation analysis experiment

[0149] See the article “Food Chem, 2020, 330:127257” for details.

[0150] Weigh 5 mg of the *Gynostemma pentaphyllum* polysaccharide prepared in Example 1 (either *Gynostemma pentaphyllum* polysaccharide 1 or *Gynostemma pentaphyllum* polysaccharide 2), dissolve in 1 mL of pure water, add 1 mL of 100 mg / mL CMC (1-cyclohexyl-2-morpholinoethyl carbodiimide methyl p-toluenesulfonate) aqueous solution, and react for 2 h. Add 1 mL of 2 mol / L imidazole aqueous solution, divide the sample into two equal portions, add 1 mL of 30 mg / mL NaBH4 aqueous solution and 1 mL of 30 mg / mL NaBD4 aqueous solution (sodium borodeuteride aqueous solution) to each portion, react for 3 h, and then add 100 μL of glacial acetic acid to terminate the reaction. Transfer to a 3500 Da dialysis bag and dialyze at 4 °C for 48 h (changing the water every 4 h), then freeze-dry under vacuum. Dissolve the sample in 500 μL of DMSO, add 1 mg of NaOH solid, and incubate for 30 min. Add 50 μL of iodomethane and react for 1 h. Add 1 mL of water and 2 mL of dichloromethane, vortex to mix, centrifuge, and discard the aqueous phase. Repeat the washing with water 3 times. Collect the lower dichloromethane phase and dry it under nitrogen. Add 1 mL of 2 mol / L imidazole aqueous solution. Divide the sample into two equal portions, adding 1 mL of 30 mg / mL NaBH4 aqueous solution and 1 mL of 30 mg / mL NaBD4 aqueous solution to each portion, and react for 3 h. Add 100 μL of 2 mol / L trifluoroacetic acid and react at 121 °C for 90 min. Evaporate to dryness at 30 °C. Add 50 μL of 2 mol / L ammonia and 50 μL of 1 mol / L NaBD4 aqueous solution, mix well, and react at room temperature for 2.5 h. Add 20 μL of acetic acid to terminate the reaction, dry under nitrogen, wash twice with 250 μL of methanol, and dry under nitrogen. Add 250 μL of acetic anhydride, vortex to mix, and react at 100 °C for 2.5 h. Add 1 mL of water and let stand for 10 min. Add 500 μL of dichloromethane, vortex to mix, centrifuge, discard the aqueous phase, and repeat the washing with water 3 times. Take the lower dichloromethane phase, filter it through a 0.22 μm organic filter membrane, and inject it into GC-MS.

[0151] GC-MS injection and analysis conditions: An Agilent 7890A gas chromatograph was used for detection. The chromatographic column was a BPX70 (30m × 0.25mm × 0.25μm) capillary column, with high-purity helium as the carrier gas. The injection volume was 1μL, and the split ratio was 10:1. The temperature program was as follows: the initial temperature of the column oven was 140℃ and held for 2.0 min, then increased to 230℃ at a rate of 3℃ / min and held for 3 min. An electron impact ionization (EI) source was used, and the analyte was detected in full scan mode. The mass scan range (m / z) was 50-350.

[0152] The methylation analysis of *Melastoma candida* polysaccharide 1 and *Melastoma candida* polysaccharide 2 obtained in Example 1 was performed using the above method. The results are as follows:

[0153] The methylation analysis of polysaccharide 1 from *Melastoma candida* was performed, and the results are shown in the table below:

[0154]

[0155] It is evident that four derivatives were obtained after methylation experiments of *Gynostemma pentaphyllum* polysaccharide 1. Based on the analysis of its methylation products and the CCRC database, the glycosidic bond composition of *Gynostemma pentaphyllum* polysaccharide 1 is mainly →4)-GalpA-(1→), and also includes a small amount of →5)-Araf-(1→, →4)-GalpA-(3→ and →2)-Rhap-(1→, with a relative molar ratio of 9.40:2.11:1.15:1.00.

[0156] Similarly, the methylation analysis of *Melastoma candida* polysaccharide 2 was performed, and the results are shown in the table below:

[0157]

[0158] As can be seen, four derivatives were obtained after the methylation experiment of Jinlingzi polysaccharide 2. According to the analysis of its methylation products and CCRC database, the glycosidic bond composition of Jinlingzi polysaccharide 2 is also mainly →4)-GalpA-(1→, and there are also a small amount of →5)-Araf-(1→, →3)-Galp-(1→ and →3)-Araf-t, with a relative molar ratio of 7.37:1.13:1.05:1.00.

[0159] 3. Nuclear Magnetic Resonance Experiment

[0160] Refer to the article "Carbohydrate Polymers, 1 February 2022, 277", for details as follows.

[0161] 30 mg of *Gynostemma pentaphyllum* polysaccharide (*Gynostemma pentaphyllum* polysaccharide 1 or *Gynostemma pentaphyllum* polysaccharide 2) was dissolved in 1 mL of 99.9% D2O and left to stand at room temperature for 12 hours to completely dissolve. The solution was then transferred to an NMR tube and analyzed using a Bruker Avance III 500 Hz NMR spectrometer equipped with a cryogenic probe (Prodigy BBO500S1). 1 H and 13 C) and two-dimensional (correlated magnetic resonance spectrum COSY, heteronuclear single quantum relation spectrum HSQC, and... 1 Analysis of the heteronuclear multicarbon correlation spectrum (HMBC) of H.

[0162] Nuclear magnetic resonance experiments were performed on the *Melia azedarach* polysaccharide 1 and polysaccharide 2 obtained in Example 1 using the above method. The results are as follows:

[0163] The NMR shifts of the residual sugars in Melia toosendan polysaccharide 1 are shown in the table below:

[0164]

[0165]

[0166] Although *Gynostemma pentaphyllum* polysaccharide 1 contains a certain amount of galactose, the wide distribution of glycosidic bond types may result in a relatively low content of each specific glycosidic bond type. This could make it difficult to detect these glycosidic bond types through methylation and NMR analysis. Furthermore, glucuronic acid, xylose, and fucose were not detected in the methylation and NMR results due to their extremely low content.

[0167] In addition, the nuclear magnetic resonance image of Jinlingzi polysaccharide 1 is as follows: Figure 2a , Figure 2b , Figure 2c , Figure 2d , Figure 2e As shown.

[0168] Based on the above analysis, the chemical structural formulas of the main polysaccharide components in *Melia azedarach* polysaccharide 1 are as follows:

[0169]

[0170] The NMR shifts of the residual sugars in Melia toosendan polysaccharide 2 are shown in the table below:

[0171]

[0172] Although *Gynostemma pentaphyllum* polysaccharide 2 contains a certain amount of rhamnose, the wide distribution of glycosidic bond types may result in a relatively low content of each specific glycosidic bond type, making it difficult to detect these glycosidic bond types through methylation and NMR analysis. Furthermore, the content of glucuronic acid, glucose, xylose, and fucose in *Gynostemma pentaphyllum* polysaccharide 2 is too low to be detected in methylation and NMR spectra.

[0173] In addition, the nuclear magnetic resonance image of Jinlingzi polysaccharide 2 is as follows: Figure 3a , Figure 3b , Figure 3c , Figure 3d , Figure 3e As shown.

[0174] Based on the above analysis, the chemical structural formulas of the main polysaccharide components in *Melia toosendan* polysaccharide 2 are as follows:

[0175]

[0176] Effect evaluation

[0177] 1. Evaluation of fat-binding capacity

[0178] Assay method: Accurately weigh 6 mg of the sample to be tested and dissolve it in 2 mL of pure water. Add 1 g of peanut oil and incubate at 37 °C with shaking for 2 h. After cooling, centrifuge (10000 g, 20 min), collect the supernatant, freeze-dry, and weigh. The amount of polysaccharide-bound oil is the actual amount of oil used minus the amount of remaining oil after freeze-drying and the mass of bound oil in the blank control. Carboxymethyl cellulose is used as a positive control, and pure water is used as a blank control.

[0179] Fat binding force = (Amount of oil bound to the polysaccharide sample ÷ Total oil content) × 100%

[0180] The lipid binding affinity of *Melastoma candida* polysaccharide 1, *Melastoma candida* polysaccharide 2, positive control carboxymethyl cellulose, *Melastoma candida* polysaccharide prepared in Comparative Example 2, and *Melastoma candida* polysaccharide prepared in Comparative Example 3 was measured respectively. The experimental results are shown in the table below:

[0181] Group Fat binding force The polysaccharide 1 prepared in Example 1 No significant fat-binding force was observed. Golden Bell Polysaccharide 2 prepared in Example 1 <![CDATA[ a 55.83%±1.68%]]> Carboxymethyl cellulose <![CDATA[ b 8.38%±1.72%]]> Comparative Example 2: Polysaccharide prepared from *Gynostemma pentaphyllum* <![CDATA[ c 20.40%±1.00%]]> Comparative Example 3: Polysaccharide prepared from *Gynostemma pentaphyllum* <![CDATA[ b 11.09%±1.48%]]>

[0182] Note: The same letter indicates no significant difference between groups (p>0.05); different letters indicate significant differences between groups (p<0.05).

[0183] As shown in the table above, the *Gynostemma pentaphyllum* polysaccharide 1 prepared in Example 1 does not have a binding effect on fat molecules; the *Gynostemma pentaphyllum* polysaccharide 2 prepared in Example 1 has a significantly higher fat binding effect compared with the *Gynostemma pentaphyllum* polysaccharide prepared in Comparative Example 2, the *Gynostemma pentaphyllum* polysaccharide prepared in Comparative Example 3, and the carboxymethyl cellulose in the positive control group.

[0184] 2. Evaluation of bile acid binding capacity

[0185] Assay method: Mix 0.1 mL of the test sample solution (10 mg / mL, pH 7.4 PBS solution) with 0.9 mL of sodium bile acid solution (2 mmol / L, pH 7.4 PBS solution). Incubate with shaking at 37 °C for 2 h. Centrifuge (12000 g, 12 min) and collect the supernatant. Mix 0.4 mL of the supernatant with 2.4 mL of 45% sulfuric acid and 0.4 mL of 0.1% furfural aqueous solution. Measure the absorbance at 620 nm. Cholestyramine is used as a positive control, and bile acid solution without sample is used as a blank control.

[0186] Bile acid binding capacity (%) = (A B -A S )÷A B ×100%

[0187] In the formula: A B A represents the absorbance of the blank group. S The absorbance values ​​are for the polysaccharide group or the positive control group.

[0188] The bile acid binding affinity of *Melastoma candida* polysaccharide 1, *Melastoma candida* polysaccharide 2, positive control cholestyramine, *Melastoma candida* polysaccharide prepared in Comparative Example 2, and *Melastoma candida* polysaccharide prepared in Comparative Example 3 was measured respectively. The experimental results are shown in the table below:

[0189] Group bile acid binding force The polysaccharide 1 prepared in Example 1 <![CDATA[ a 18.85%±1.38%]]> Golden Bell Polysaccharide 2 prepared in Example 1 <![CDATA[ a 20.76%±0.22%]]> Cholestyramine <![CDATA[ b 28.61%±1.19%]]> Comparative Example 2: Polysaccharide prepared from *Gynostemma pentaphyllum* <![CDATA[ c 11.94%±0.85%]]> Comparative Example 3: Polysaccharide prepared from *Gynostemma pentaphyllum* <![CDATA[ c 9.20%±2.20%]]>

[0190] Note: The same letter indicates no significant difference between groups (p>0.05); different letters indicate significant differences between groups (p<0.05).

[0191] As shown in the table above, although the bile acid binding capacity of the *Gynostemma pentaphyllum* polysaccharide 1 and polysaccharide 2 prepared in Example 1 is not as high as that of the bile acid binding capacity of the positive control group cholestyramine, it is significantly higher than that of the bile acid binding capacity of the *Gynostemma pentaphyllum* polysaccharides prepared in Comparative Examples 2 and 3.

[0192] 3. Evaluation of cholesterol binding capacity

[0193] Assay Method: First, prepare the cholesterol micelle solution: Prepare a mixed aqueous solution of 10 mmol / L sodium taurocholate, 10 mmol / L cholesterol, 5 mmol / L oleic acid, and 132 mmol / L NaCl using pH 7.4 PBS, and sonicate at 480 W for 1 h to aid dissolution. Accurately weigh 5 mg of the sample to be tested, add 3 mL of cholesterol micelle solution, and incubate with shaking at 37 °C for 2 h. Centrifuge (10000 g, 1 h) and collect the supernatant. Determine the cholesterol content in the supernatant using a commercial cholesterol reagent kit. Carboxymethyl cellulose was used as a positive control, and pure water was used as a blank control.

[0194] Cholesterol binding force = (C B -C S )÷C B ×100%

[0195] In the formula: C B Cholesterol content (g) in the blank group; C S The cholesterol content (g) represents the content of the polysaccharide group or the positive control group.

[0196] The cholesterol-binding affinity of *Melastoma candida* polysaccharide 1, *Melastoma candida* polysaccharide 2, positive control carboxymethyl cellulose, *Melastoma candida* polysaccharide prepared in Comparative Example 2, and *Melastoma candida* polysaccharide prepared in Comparative Example 3 was measured respectively. The experimental results are shown in the table below:

[0197] Group Cholesterol binding power The polysaccharide 1 prepared in Example 1 <![CDATA[ a 25.16%±0.20%]]> Golden Bell Polysaccharide 2 prepared in Example 1 <![CDATA[ b 42.72%±2.75% <!-- 13 -->]]> Carboxymethyl cellulose <![CDATA[ c 49.86%±1.77%]]> Comparative Example 2: Polysaccharide prepared from *Gynostemma pentaphyllum* <![CDATA[ d 14.08%±1.14%]]> Comparative Example 3: Polysaccharide prepared from *Gynostemma pentaphyllum* <![CDATA[ d 18.75%±2.69%]]>

[0198] Note: The same letter indicates no significant difference between groups (p>0.05); different letters indicate significant differences between groups (p<0.05).

[0199] As shown in the table above, although the cholesterol binding capacity of the *Gynostemma pentaphyllum* polysaccharide 1 and polysaccharide 2 prepared in Example 1 is not as high as that of the carboxymethyl cellulose in the positive control group, it is significantly higher than that of the *Gynostemma pentaphyllum* polysaccharides prepared in Comparative Examples 2 and 3.

[0200] 4. Evaluation of lipase inhibition capacity

[0201] Assay method: Accurately weigh the sample to be tested and prepare sample solutions of 50, 125, 250, 500, and 750 μg / mL using PBS buffer (pH=7.4). Dissolve orlistat with a small amount of DMSO (mass fraction not exceeding 1%), then add an appropriate amount of buffer solution and sonicate to prepare solutions of five concentrations of 50, 125, 250, 500, and 750 μg / mL.

[0202] Weigh 1.4 mg of pancreatic lipase (20 U / mg) and dissolve it in 10 mL of pH 7.4 PBS solution. Centrifuge (8000 g, 10 min), collect the supernatant, and dilute 20-fold. Accurately weigh 0.156 g of PNPP (disodium 4-nitrophenyl phosphate) and dissolve it in 0.3 mL of N,N-dimethylformamide. Adjust the volume to 100 mL with buffer. Add 50 μL of sample solution / positive control solution / pure water and 50 μL of pH 7.4 PBS to a 96-well plate. Add 50 μL of lipase solution and incubate at 37 °C with shaking for 10 min. Add 50 μL of PNPP solution and continue incubating at 37 °C with shaking for 20 min. Measure the absorbance at 405 nm.

[0203] Lipase inhibition rate (%) = (1 - (A1 - A2) ÷ (B1 - B2)) × 100%

[0204] In the formula: A1 is the absorbance of PBS + lipase + sample / positive control solution; A2 is the absorbance of PBS + sample solution; B1 is the absorbance of PBS + lipase solution; B2 is the absorbance of PBS.

[0205] The lipase inhibitory activity of *Melastoma candida* polysaccharide 1, *Melastoma candida* polysaccharide 2, positive control orlistat, *Melastoma candida* polysaccharide prepared in Comparative Example 2, and *Melastoma candida* polysaccharide prepared in Comparative Example 3 was measured respectively. The experimental results are shown in the table below:

[0206]

[0207] Note: ** indicates a significant difference compared to the positive control group at the same concentration, and p < 0.01.

[0208] As shown in the table above, the *Lysimachia christinae* polysaccharide 2 prepared in Example 1 has a certain lipase inhibitory effect, and at a concentration of 750 μg / mL, it is superior to the positive control orlistat in lipase inhibition. However, the *Lysimachia christinae* polysaccharides prepared in Comparative Examples 2 and 3, and the *Lysimachia christinae* polysaccharide 1 prepared in Example 1, did not show significant lipase inhibitory effects.

[0209] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A polysaccharide from *Gynostemma pentaphyllum*, characterized in that, It includes at least one of *Melia azedarach* polysaccharide 1 and *Melia azedarach* polysaccharide 2, wherein *Melia azedarach* polysaccharide 1 comprises a polysaccharide molecule represented by formula (I): Formula (I); The golden bell polysaccharide 2 comprises the polysaccharide molecule shown in formula (II): Formula (II); The polysaccharide 1 from the golden bell fruit comprises the following structural units: galacturonic acid, galactose, rhamnose, and arabinose; The polysaccharide 2 from the golden bell fruit comprises the following structural units: galacturonic acid, galactose, rhamnose, and arabinose; The golden bell polysaccharide 1 includes the following types of glycosidic bonds: →4)-GalpA-(1→, →5)-Araf-(1→, →4)-GalpA-(3→, →2)-Rhap-(1→; The polysaccharide 2 of *Gynostemma pentaphyllum* includes the following type of glycosidic bond: →4)-GalpA-(1→、→5)-Araf-(1→、→3)-Galp-(1→、→3)-Araf-t.

2. The *Melastoma candida* polysaccharide according to claim 1, characterized in that, The total sugar content of the *Gynostemma pentaphyllum* polysaccharide 1 is 82.82% ± 1.29%; the total sugar content of the *Gynostemma pentaphyllum* polysaccharide 2 is 84.97% ± 2.34%.

3. The *Melastoma candida* polysaccharide according to claim 1, characterized in that, The total protein content of the *Gynostemma pentaphyllum* polysaccharide 1 is 1.67% ± 0.04%; the total protein content of the *Gynostemma pentaphyllum* polysaccharide 2 is 0.21% ± 0.01%.

4. The method for extracting polysaccharides from *Melastoma candida* according to any one of claims 1-3, characterized in that, Includes the following steps: S1. Mix the pericarp of the golden bell fruit with water, extract, and concentrate to obtain an aqueous extract; S2. Add ethanol to the aqueous extract obtained in step S1, and precipitate with alcohol to obtain the first precipitate and supernatant. S3. Add ethanol to the supernatant obtained in step S2 and precipitate to obtain a second precipitate. S4. Purify and dialyze the first precipitate obtained in step S2 to obtain the first polysaccharide; S5. Purify and dialyze the second precipitate obtained in step S3 to obtain the second polysaccharide; S6. Purify the first polysaccharide obtained in step S4, collect polysaccharides with a molecular weight of 30-34kDa, and obtain Jinlingzi polysaccharide 1; S7. Purify the second polysaccharide obtained in step S5, collect polysaccharides with a molecular weight of 5.0-5.5 kDa, and obtain Jinlingzi polysaccharide 2; In step S2, the volume ratio of the aqueous extract to the ethanol is 1:0.5-2. In step S3, the volume ratio of the supernatant to the ethanol is 1:0.5-2.

5. The extraction method according to claim 4, characterized in that, In step S1, the mixing with water is homogenization in water, the extraction is ultrasound-assisted extraction, and the ratio of the mass of the golden bell fruit peel to the volume of the water is 1g:5-30mL.

6. The extraction method according to claim 4, characterized in that, In step S4, the purification process involves removing proteins and pigments, and the dialysis is followed by lyophilization. In step S5, the purification process involves removing proteins and pigments, and the dialysis is followed by freeze drying. In step S6, the purification is performed by anion exchange chromatography and dextran gel chromatography; in step S7, the purification is performed by anion exchange chromatography and dextran gel chromatography.

7. The use of the *Gynostemma pentaphyllum* polysaccharide according to any one of claims 1-3 or the *Gynostemma pentaphyllum* polysaccharide extracted by the extraction method according to any one of claims 4-6 in the preparation of lipid-lowering products.

8. A lipid-lowering product, characterized in that, The lipid-lowering product includes the *Gynostemma pentaphyllum* polysaccharide as described in any one of claims 1-3 or the *Gynostemma pentaphyllum* polysaccharide extracted by the extraction method described in any one of claims 4-6.

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