A small white mouth yam polysaccharide myocardial protection composition, and a preparation method and application thereof

Abstract

This invention discloses a myocardial protective composition of *Dioscorea opposita* polysaccharide, its preparation method, and its application, belonging to the field of natural products and functional foods. The active ingredient of the composition is one or a combination of *Dioscorea opposita* polysaccharide and *Dioscorea cirrhosa* polysaccharide. This polysaccharide is a neutral heteropolysaccharide mainly composed of glucose, with glucose accounting for more than 96% of the total monosaccharide mass. The two polysaccharides have highly similar molecular weight distributions and core structural characteristics. This invention demonstrates that the yam polysaccharide can dose-dependently improve the viability of cardiomyocytes after oxygen-glucose deprivation / reoxygenation injury, and reduce the levels of myocardial injury markers CK-MB and cTnT, and the oxidative stress marker 8-OHdG. Its core mechanism of action is the regulation of the MyD88-mediated MAPK / NF-κB signaling pathway, inhibiting the stress and inflammatory cascade response of cardiomyocytes. The yam polysaccharide composition of this invention has widely available raw materials, a simple preparation process, and high safety. It can be widely used in the preparation of pharmaceuticals, health foods, functional foods, and other products for the prevention / improvement of myocardial ischemia-reperfusion injury, and has broad application prospects.

Description

Technical Field

[0001] This invention belongs to the fields of extraction of natural products that are both food and medicine, biomedicine and functional food technology, specifically relating to a polysaccharide composition of Chinese yam with cardioprotective effects, and the application of this composition in the preparation of products for preventing / improving myocardial ischemia-reperfusion injury. Background Technology

[0002] Cardiovascular disease is the leading cause of death among Chinese residents, with acute myocardial infarction (AMI) having a persistently high incidence and mortality rate. Percutaneous coronary intervention (PCI) is the preferred treatment for AMI, but post-PCI myocardial ischemia-reperfusion (I / R) injury is a core clinical challenge that cannot be avoided. Its pathological mechanism is closely related to hypoxia-reoxygenation induced myocardial oxidative stress, inflammatory cascade, and apoptosis. Currently, there is a lack of safe and long-term dietary intervention agents available in clinical practice.

[0003] Yam (Dioscorea opposita Thunb.) is one of the first crops approved for both medicinal and edible purposes in my country, with a cultivation history of over 3,000 years. It is listed as a superior herb in the *Shennong Bencao Jing* (Shennong's Classic of Materia Medica), and traditional Chinese medicine believes it has the effects of strengthening the spleen and kidneys, and consolidating the body's foundation. In modern times, it is widely used as a staple food, side dish, and ingredient in medicinal cuisine. The mainstream edible yam varieties in my country are Tiegun yam (mainly produced in Wenxian County, Henan Province, and is the core variety of Huai yam) and Xiaobaizui yam (mainly produced in Hebei and other northern regions, with a soft and glutinous texture and high consumption rate).

[0004] Existing technologies for the study of yam have the following core shortcomings: Existing research mainly focuses on the hypoglycemic, hypolipidemic, and immunomodulatory activities of yam polysaccharides. However, systematic reviews on the cardioprotective effects of yam polysaccharides, especially myocardial ischemia-reperfusion injury, are extremely scarce. The few existing studies only use crude extracts and have not clarified the structural characteristics, targets, and molecular mechanisms of the active ingredients, thus failing to provide a scientific basis for industrial applications.

[0005] Existing research has not conducted a systematic parallel comparison of the structural characteristics and biological activities of polysaccharides from Xiaobaizui and Tiegun, the two most consumed yam varieties in China. There is a common misconception in the industry that "only Tiegun yam has high medicinal activity," which completely limits the high-value application of Xiaobaizui yam and makes it impossible to guarantee the activity stability of different batches of raw materials.

[0006] Existing techniques for preparing yam polysaccharides generally require complex steps such as repeated protein removal using the Sevage method, multi-stage dialysis using dialysis bags, and purification by column chromatography. These methods are not only costly and time-consuming, but also lead to loss of polysaccharide activity and low extraction rates, making it impossible to achieve large-scale industrial production. Furthermore, it has not been confirmed whether crude polysaccharides possess stable cardioprotective activity.

[0007] Existing technologies do not clearly define the core quality control indicators (monosaccharide composition, molecular weight distribution) for yam polysaccharides with cardioprotective activity, making it impossible to achieve standardized production and quality control of the product.

[0008] In summary, the development of a myocardial protective yam polysaccharide composition based on mainstream edible yam varieties, with a well-defined structure, stable activity, simple processing, and standardized production capability fills a gap in existing technologies and has significant clinical value and industrialization implications. Summary of the Invention

[0009] To address the shortcomings of existing technologies, one objective of this invention is to provide a polysaccharide composition of *Dioscorea opposita* with cardioprotective effects that has a well-defined structure, stable activity, wide availability of raw materials, and a simple and controllable preparation method, filling a gap in the industry research on the cardioprotective activity of *Dioscorea opposita* polysaccharide. Another objective of this invention is to provide the application of this *Dioscorea opposita* polysaccharide composition in the preparation of products with cardioprotective effects, clarify its mechanism of action, and provide a scientific basis for its application in cardiovascular health-related pharmaceuticals and functional foods.

[0010] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a polysaccharide composition of Dioscorea opposita with cardioprotective effects. The active ingredient of the composition is yam polysaccharide; the yam polysaccharide is selected from yam polysaccharide of *Dioscorea opposita*, or a combination of yam polysaccharide of *Dioscorea opposita* and yam polysaccharide of *Dioscorea cirrhosa*; the yam polysaccharide is a neutral heteropolysaccharide, and its monosaccharide composition is mainly glucose, which accounts for more than 96% of the total monosaccharide mass.

[0011] Furthermore, in the monosaccharide composition of the *Dioscorea opposita* polysaccharide, glucose accounts for 96.8% to 97.4% of the total monosaccharide mass, galactose accounts for 2.2% to 2.6% of the total monosaccharide mass, and mannose is not present; in the monosaccharide composition of the *Dioscorea cirrhosa* polysaccharide, glucose accounts for 96.8% to 97.4% of the total monosaccharide mass, galactose accounts for 2.2% to 2.6% of the total monosaccharide mass, and mannose also accounts for 1.0% of the total monosaccharide mass.

[0012] Furthermore, the molecular weight distribution range of the yam polysaccharide is 4kDa~450kDa, and it has 5 molecular weight distribution components, wherein: the number average molecular weights of the 5 components of the *Dioscorea opposita* polysaccharide are 370921Da, 172366Da, 55852Da, 12308Da, and 4984Da, respectively; and the number average molecular weights of the 5 components of the *Dioscorea cirrhosa* polysaccharide are 405880Da, 166687Da, 61314Da, 10746Da, and 4836Da, respectively.

[0013] Furthermore, the polysaccharide from *Dioscorea opposita* is prepared through the following steps: S1 Defatting Pretreatment: After washing, slicing, drying and crushing the tubers of the Chinese yam, the tubers were extracted by reflux with a 70% ethanol solution to remove lipophilic components and small molecule impurities. The residue was collected after filtration. S2 hot water extraction: Add distilled water to the filter residue obtained in S1 at a material-to-liquid ratio of 1:10 g / mL, reflux and extract twice, each time for 2 hours, combine the two water extracts, and concentrate the water extract under reduced pressure to obtain a concentrated solution. S3 Alcohol precipitation and drying: Add anhydrous ethanol to the concentrated solution obtained in S2 until the final volume fraction of ethanol in the system is 70%. Let it stand overnight at 4°C, collect the precipitate by centrifugation, wash the precipitate with anhydrous ethanol and freeze dry to obtain the polysaccharide of yam. The preparation method of the polysaccharide of Dioscorea opposita is the same as the above steps, except that the raw material is replaced with Dioscorea opposita tuber.

[0014] Furthermore, the composition is a pharmaceutical, health food, functional food, or dietary supplement; when the composition is a pharmaceutical, it also contains pharmaceutically acceptable excipients; when the composition is a health food, functional food, or dietary supplement, it also contains food-acceptable excipients; the active ingredient of the composition is yam polysaccharide as the core.

[0015] Secondly, this invention provides the application of *Dioscorea opposita* polysaccharide in the preparation of products with myocardial protective effects. The yam polysaccharide is selected from *Dioscorea opposita* polysaccharide, or a combination of *Dioscorea opposita* polysaccharide and *Dioscorea cirrhosa* polysaccharide; the *Dioscorea opposita* polysaccharide is a neutral heteropolysaccharide, with glucose as the main monosaccharide component; in the monosaccharide composition of the *Dioscorea opposita* polysaccharide, glucose accounts for 96.8%~97.4% of the total monosaccharide mass, galactose accounts for 2.2%~2.6% of the total monosaccharide mass, and it does not contain mannose; in the monosaccharide composition of the *Dioscorea cirrhosa* polysaccharide, glucose accounts for 96.8%~97.4% of the total monosaccharide mass, galactose accounts for 2.2%~2.6% of the total monosaccharide mass, and it also contains 1.0% mannose of the total monosaccharide mass.

[0016] Furthermore, the cardioprotective effect is the protective effect of yam polysaccharide against myocardial ischemia-reperfusion injury, including at least one of improving cardiomyocyte vitality, reducing cardiomyocyte membrane damage, and alleviating myocardial cell oxidative stress injury.

[0017] Furthermore, the reduction of myocardial cell membrane damage is achieved by yam polysaccharide reducing the release levels of creatine kinase isoenzyme CK-MB and cardiac troponin TcTnT; the relief of myocardial cell oxidative stress damage is achieved by yam polysaccharide reducing the level of 8-hydroxy-2'-deoxyguanosine 8-OHdG, a marker of oxidative DNA damage.

[0018] Furthermore, the polysaccharide from *Dioscorea opposita* exerts a cardioprotective effect by regulating the MyD88-mediated MAPK / NF-κB signaling pathway by downregulating MyD88 protein expression and inhibiting the phosphorylation of p38MAPK and NF-κBp65.

[0019] Furthermore, the product is any one of pharmaceuticals, health foods, functional foods, or dietary supplements, and the core active ingredient of the product is yam polysaccharide.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects: With a clearly defined structure and strong batch stability, this invention breaks through industry misconceptions: For the first time, this invention systematically clarifies the core structural features of Xiaobaizui yam polysaccharide and compares it with the structure of Tiegun yam polysaccharide, confirming that the two have highly similar molecular weight distributions, monosaccharide composition mainly composed of dextran, and characteristic polysaccharide functional groups. The differences between varieties are only the molecular heterogeneity and moderate changes in the monosaccharide ratio. This confirms that Xiaobaizui yam polysaccharide has the same stable structural consistency as Tiegun yam polysaccharide, solving the problems of unclear structure and activity of Xiaobaizui yam polysaccharide and limited high-value applications in the prior art.

[0021] The cardioprotective activity is clear and the effect is significant: This invention systematically verified the cardioprotective effect of *Dioscorea opposita* polysaccharide using an in vitro myocardial oxygen deprivation / reoxygenation (OGD / R) injury model. It confirmed that it can dose-dependently improve the viability of damaged cardiomyocytes, and can restore cell viability to 70%~80% of normal levels at a concentration of 100 μg / mL. At the same time, it can significantly reduce the release of myocardial injury markers CK-MB and cTnT, alleviate myocardial cell membrane damage, reduce the level of oxidative DNA damage marker 8-OHdG, and relieve myocardial oxidative stress, providing sufficient experimental evidence for the cardioprotective application of *Dioscorea opposita* polysaccharide.

[0022] The mechanism of action is clear and the theoretical basis is sufficient: This invention, through combined transcriptomics and proteomics analysis and Western blot verification, clarifies the core molecular mechanism by which *Dioscorea opposita* polysaccharide exerts its cardioprotective effect—by regulating the MyD88-mediated MAPK / NF-κB signaling pathway, downregulating MyD88 protein expression, inhibiting the phosphorylation of p38 MAPK and NF-κBp65, and thus inhibiting the hypoxia-reoxygenation-induced cardiomyocyte stress and inflammation cascade response, filling the research gap in the existing technology regarding the cardioprotective mechanism of *Dioscorea opposita* polysaccharide.

[0023] The raw materials are widely available and the preparation process is simple and controllable: The white yam used in this invention is a mainstream edible variety that is widely cultivated in northern my country. The raw materials are readily available and inexpensive. The hot water extraction-alcohol precipitation preparation process is simple, mild, and highly reproducible. It does not require complicated purification steps. The polysaccharide extraction yield of white yam is stable at 7.5%, which is easy to scale up for industrial production and has extremely high industrialization value.

[0024] With wide application scenarios and high safety, the yam polysaccharide composition of this invention is derived from food and medicine homologous raw materials. It has no cytotoxicity within the tested concentration range and has good biocompatibility. It can be developed into a variety of products such as drugs, health foods, functional foods, and dietary supplements for cardiovascular health protection. It can provide new drug candidates for the clinical adjuvant treatment of myocardial ischemia-reperfusion injury and also provide a safe cardiovascular health dietary supplement for the general population, with broad application prospects. Attached Figure Description

[0025] Figure 1 The images show the morphological characteristics of Chinese yam (Dioscorea opposita) and Chinese yam (Dioscorea cirrhosa), where A is the whole tuber and cross-section of Chinese yam (Dioscorea opposita) and B is the whole tuber and cross-section of Chinese yam (Dioscorea cirrhosa). Figure 2 The chemical characterization diagrams for two yam polysaccharides are shown below. A represents the gel permeation chromatography (GPC) molecular weight distribution of *Dioscorea opposita* polysaccharide (CYP-XBZ) and *Dioscorea glutinosa* polysaccharide (CYP-TG); B represents the ion chromatography monosaccharide composition of the two yam polysaccharides; C represents the UV-Vis absorption spectra of the two yam polysaccharides; and D represents the Fourier transform infrared (FT-IR) spectra of the two yam polysaccharides. Figure 3 The diagram shows the protective effect of yam polysaccharides against OGD / R-induced H9c2 cardiomyocyte injury. A represents the effect of CYP-XBZ on the basal viability of normal H9c2 cells; B represents the effect of CYP-TG on the basal viability of normal H9c2 cells; C represents the dose-response relationship of the two yam polysaccharides on the viability of H9c2 cells after OGD / R injury; and D and F represent the regulatory effects of the two yam polysaccharides on the levels of CK-MB, cTnT, and 8-OHdG in cells after OGD / R injury, respectively. Figure 4 Transcriptomic analysis of OGD / R-damaged H9c2 cells after yam polysaccharide treatment is shown. AB represents the volcano plots of differentially expressed genes between the CYP-XBZ and CYP-TG treatment groups and the model group, respectively; CD represents the KEGG pathway enrichment analysis of differentially expressed genes in the two groups; EF represents the gene set enrichment analysis (GSEA) of the MAPK and NF-κB signaling pathways in the two groups; G represents the Venn diagram of differentially expressed genes in the two groups; and H represents the KEGG pathway enrichment analysis of shared differentially expressed genes in the two groups. Figure 5 This is a proteomic analysis diagram of OGD / R-damaged H9c2 cells after treatment with yam polysaccharide. AC represents the volcano plots of differentially expressed proteins between the model group and the control group, CYP-XBZ and the model group, and CYP-TG and the model group, respectively. DF represents the KEGG pathway enrichment analysis diagrams of the three groups of differentially expressed proteins. G represents the Venn diagram of the three groups of differentially expressed proteins. H represents the KEGG pathway enrichment analysis diagram of shared differentially expressed proteins. I represents the protein-protein interaction (PPI) network diagram of MAPK pathway-related differentially expressed proteins. Figure 6 This diagram validates the regulatory effect of yam polysaccharide on the MyD88-mediated MAPK / NF-κB signaling pathway. In the diagram, A represents the relative expression level of MyD88 protein; B represents the phosphorylation level of NF-κBp65; C represents the phosphorylation level of p38MAPK; and D represents the relative expression level of CEBPB protein. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to specific embodiments, comparative examples, and experimental examples. It should be understood that the embodiments described herein are only for explaining the present invention and are not intended to limit the scope of protection of the present invention.

[0027] The raw materials and reagents used in this invention embodiment were sourced from: fresh tubers of *Dioscorea opposita* (small white yam) were collected from the main producing area of ​​Anguo City, Hebei Province; and fresh tubers of *Dioscorea cirrhosa* (iron stick yam) were collected from the main producing area of ​​Wenxian County, Henan Province. Both were identified as varieties. Dioscoreaopposita Thunb.; monosaccharide control standards (arabinose, galactose, glucose, mannose, etc.) were purchased from Shanghai Yuanye Biotechnology Co., Ltd.; chromatographic grade acetonitrile and methanol were purchased from Thermo Fisher Scientific; analytical grade reagents were purchased from Sigma-Aldrich; H9c2 rat cardiomyocytes were purchased from the Shanghai Cell Bank of the Chinese Academy of Sciences; cell culture reagents were purchased from Dalian Meilun Biotechnology; detection kits were purchased from Nanjing Jiancheng Biotechnology Institute; and primary and secondary antibodies for Western blotting were purchased from Cell Signaling Technology. Example

[0028] Example 1: Preparation of Polysaccharide from Chinese Yam (Dioscorea opposita) The specific steps for preparing the polysaccharide from *Dioscorea opposita* (named CYP-XBZ) in this embodiment are as follows: S1 Degreasing Pretreatment: Take fresh small white yam tubers, wash them with running water to remove surface mud and impurities, peel them by hand, cut them into uniform slices 2mm thick, place them in a 50℃ constant temperature forced-air drying oven to dry to constant weight, pulverize them using a high-speed universal pulverizer, and pass them through an 80-mesh standard sieve to obtain small white yam powder; accurately weigh 30g of yam powder, place it in a 500mL round-bottom flask, add 300mL of 70% ethanol solution, shake well, and place it in a water bath for reflux extraction twice, refluxing for 1 hour each time, to remove lipophilic components, monosaccharides, oligosaccharides, saponins and other small molecule impurities from the raw material; after reflux, filter while hot using double-layer qualitative filter paper, collect the filter residue, place it in a fume hood to evaporate the residual ethanol in the filter residue, and set aside for later use; S2 Hot Water Reflux Extraction: Transfer the ethanol-evaporated residue from S1 to a 500mL round-bottom flask, add 300mL of distilled water at a material-to-liquid ratio of 1:10 (g:mL), shake well, and place in a water bath. Heat to boiling and reflux twice, each extraction lasting 2 hours. After each extraction, filter through 4 layers of medical gauze, combine the two filtrations, and transfer the aqueous extract to a rotary evaporator. Concentrate under reduced pressure at 60℃ and a vacuum of -0.09MPa until the volume of the concentrate is 1 / 10 of the original volume of the aqueous extract to obtain the concentrated extract of yam polysaccharide. S3 Alcohol Precipitation and Drying: Anhydrous ethanol was slowly added to the polysaccharide concentrate obtained in S2 under uniform stirring until the final volume fraction of ethanol in the system reached 70%. After the addition was complete, stirring was continued for 5 minutes. The bottle was sealed and placed in a medical refrigerator at 4°C overnight (12 hours) to allow the polysaccharide to precipitate fully. After standing, the precipitate was transferred to a centrifuge tube and centrifuged at 4000×g for 10 minutes. The supernatant was discarded, and the bottom precipitate was collected. The precipitate was washed three times with anhydrous ethanol, each time using three times the volume of the precipitate. After washing, the supernatant was discarded by centrifugation. The washed precipitate was placed in a vacuum freeze dryer and freeze-dried at -55°C and a vacuum of 10Pa until constant weight was obtained to obtain white flocculent powder of Dioscorea opposita polysaccharide (CYP-XBZ). The polysaccharide extraction yield of this example was calculated to be 7.5%.

[0029] Example 2: Preparation of Polysaccharide from Dioscorea opposita In this embodiment, the preparation of yam polysaccharide (named CYP-TG) is carried out in the same steps as in Example 1, except that the raw material is replaced with yam tuber. The final product is a white flocculent powder of yam polysaccharide (CYP-TG). The polysaccharide extraction yield of this embodiment is calculated to be 7.4%.

[0030] Example 3: Preparation of the compound composition of *Dioscorea opposita* and *Dioscorea cirrhosa* polysaccharides This embodiment prepares a compound composition of two yam polysaccharides, and the specific steps are as follows: Accurately weigh 50g of CYP-XBZ powder prepared in Example 1 and 50g of CYP-TG powder prepared in Example 2, place them in a three-dimensional motion mixer, and mix at a speed of 20r / min for 30 minutes until the powder is completely uniform. This yields a 1:1 mass ratio yam polysaccharide compound composition. This composition combines the polysaccharide structural characteristics of both varieties, exhibits stable activity between batches, and can be directly used for downstream product development.

[0031] Example 4: Preparation of yam polysaccharide composition tablets (chemical drug / traditional Chinese medicine preparation) This embodiment describes the preparation of yam polysaccharide tablets for adjuvant treatment of myocardial ischemia-reperfusion injury. The specific formulation and preparation method are as follows: Prescription (dosage for 1000 tablets): 100g of CYP-XBZ prepared in Example 1, 80g of microcrystalline cellulose, 15g of crospovidone, 10g of low-substituted hydroxypropyl cellulose, and 2g of magnesium stearate; Preparation method: Pass all raw and excipient materials in the prescribed amount through a 100-mesh standard sieve. Mix CYP-XBZ with the remaining excipients evenly according to the equal incremental method. After the intermediate content is qualified, compress the powder directly into tablets, controlling the tablet weight to be 0.207g / tablet and the hardness to be 4-6kg, thus obtaining yam polysaccharide tablets. Each tablet contains 100mg of active ingredient yam polysaccharide. The clinically recommended oral dose is 1-2 tablets twice a day.

[0032] Example 5: Preparation of hard capsules (health food) of yam polysaccharide composition This embodiment describes the preparation of a hard capsule for a health food product used to assist in the protection of myocardial function. The specific formula and preparation method are as follows: Prescription (dosage for 1000 capsules): 100g of CYP-TG prepared in Example 2, 50g of pregelatinized starch, and 2g of micronized silica gel; Preparation method: Pass all raw and auxiliary materials in the prescription amount through an 80-mesh standard sieve, place them in a trough mixer and mix for 20 minutes until uniform. After the intermediate content is tested and found to be qualified, use a fully automatic capsule filling machine to fill them into No. 1 gelatin hard capsules, controlling the weight of each capsule's contents to be 0.152g, thus obtaining yam polysaccharide hard capsules. Each capsule contains 100mg of yam polysaccharide active ingredient. The health function is claimed to be "assist in protecting myocardial function". The recommended dosage is 1 capsule twice a day.

[0033] Example 6: Preparation of Lyophilized Powder Injection of Yam Polysaccharide Composition This embodiment describes the preparation of a lyophilized powder injection of yam polysaccharide for intravenous administration. The specific formulation and preparation method are as follows: Prescription (dosage for 1000 vials): 50g of CYP-XBZ prepared in Example 1, 40g of mannitol, and water for injection to a final volume of 1000mL; Preparation method: Under a Class 10,000 clean environment, weigh the prescribed amount of CYP-XBZ and mannitol, add 800 mL of water for injection at 25℃, stir until completely dissolved, add water for injection to 1000 mL, and stir evenly; add 0.1% (g / mL) of activated carbon for injection to the solution, stir and adsorb at 25℃ for 30 minutes, filter with a titanium rod filter to remove carbon, and then filter the filtrate through a 0.22 μm polyethersulfone microporous membrane for two-stage sterilization; fill the filtrate into controlled vials at a filling volume of 1 mL / vial, half-press butyl rubber stoppers, place in a vacuum freeze dryer, freeze dry according to the preset freeze-drying curve, after freeze-drying, press the stopper, roll the aluminum-plastic cap, and package after passing full inspection to obtain the yam polysaccharide freeze-dried powder injection, each vial containing 50 mg of yam polysaccharide active ingredient, for intravenous drip administration.

[0034] Example 7: Preparation of Yam Polysaccharide Functional Oral Liquid (Dietary Supplement) This embodiment prepares a functional oral liquid of yam polysaccharides for daily cardiovascular health maintenance. The specific prescription and preparation method are as follows: Prescription (dosage for 1000 vials, 10mL / vial): 50g of CYP-XBZ prepared in Example 1, 50g of CYP-TG prepared in Example 2, 100g of xylitol, 2g of citric acid, 0.5g of potassium sorbate, and purified water to 10L; Preparation method: Add the prescribed amount of yam polysaccharide, xylitol, and citric acid to 8L of purified water at 40℃, stir until completely dissolved, add potassium sorbate, and add purified water to 10L, stir evenly; the solution is coarsely filtered through a 0.45μm microporous membrane and finely filtered through a 0.22μm microporous membrane. The filtrate is filled into brown oral liquid bottles at a filling volume of 10mL / bottle, sealed, and sterilized by moist heat at 115℃ for 30 minutes. After passing the light inspection, it is packaged to obtain yam polysaccharide functional oral liquid. Each bottle contains 100mg of active ingredient of yam polysaccharide. The recommended dosage is 1-2 bottles per day.

[0035] Example 8: Preparation of functional meal replacement powder (special dietary food) made from yam polysaccharides This embodiment prepares yam polysaccharide meal replacement powder for high-risk groups of cardiovascular disease. The specific formula and preparation method are as follows: Prescription (1000g batch): 20g of CYP-TG prepared in Example 2, 500g of oat flour, 200g of quinoa flour, 100g of whole milk powder, 80g of fructooligosaccharides, and 20g of compound vitamin and mineral premix; Preparation method: Pass all raw materials through an 80-mesh standard sieve, weigh them precisely according to the prescription, place them in a three-dimensional motion mixer, mix at 25 r / min for 40 minutes until completely uniform, and after the intermediate content is tested and found to be qualified, package them in aluminum-plastic composite film according to the specification of 30g / bag to obtain yam polysaccharide meal replacement powder. Each bag contains 0.6g of active ingredient of yam polysaccharide and can be used as a meal replacement for breakfast or dinner.

[0036] II. Comparative Example Comparative Example 1: Preparation of refined yam polysaccharides using existing techniques The preparation method follows the conventional purification method used in existing research on yam polysaccharides, with the following specific steps: The *Dioscorea opposita* powder from Example 1 was used to prepare crude polysaccharide according to steps S1-S3 of Example 1. The crude polysaccharide was redissolved in distilled water to prepare a 10 mg / mL polysaccharide aqueous solution. The protein was repeatedly removed 8 times using the Sevage method (chloroform:n-butanol = 4:1, v:v) until no protein was detected by the phenol-sulfuric acid method. The deproteinized polysaccharide solution was placed in a dialysis bag with a molecular weight cutoff of 3500 Da and dialyzed with running water for 72 hours and distilled water for 24 hours. After dialysis, the polysaccharide solution was concentrated under reduced pressure, and anhydrous ethanol was added to a final volume fraction of 70%. The solution was allowed to stand overnight at 4°C, and the precipitate was collected by centrifugation and freeze-dried to obtain refined yam polysaccharide. The calculated extraction yield was only 2.1%, which is 72% lower than the extraction yield of the process in Example 1 of this invention.

[0037] Comparative Example 2: Preparation of Polysaccharides from Common Chinese Yam The raw material was replaced with common Chinese yam tubers, and the common Chinese yam polysaccharide was prepared according to the exact same steps as in Example 1. The final product was Chinese yam polysaccharide powder. The calculated extraction yield was 4.2%, which was significantly lower than that of the Chinese yam polysaccharide of the present invention.

[0038] III. Verification Experiment Examples Experimental Example 1: Structural Characterization and Establishment of Quality Control Standards for Yam Polysaccharides This experiment comprehensively characterized the physicochemical and structural properties of the yam polysaccharides prepared in Examples 1 and 2, and established core quality control standards that matched the cardioprotective activity. The specific experimental methods and results are as follows: 1.1 Determination of molecular weight distribution characteristics The molecular weight distribution of two yam polysaccharides was determined by gel permeation chromatography (GPC). Specific chromatographic conditions were as follows: Waters E2695 high-performance liquid chromatography system equipped with a 2414 differential refractive index detector; PLAquagel-OHMIXED-M gel chromatography column (7.5 mm × 300 mm, 8 μm); column temperature 40 ℃; mobile phase: ultrapure water; flow rate 1.0 mL / min; injection volume 20 μL; run time 35 minutes.

[0039] Standard curve plotting: A molecular weight range of 1×10³ to 1×10³ was used. 6 For linear polyethylene glycol (PEG) standards of Da, prepare standard solutions of 5 mg / mL and inject them for detection under the above chromatographic conditions. Plot a standard curve with retention time as the x-axis and the logarithm of molecular weight as the y-axis to obtain the regression equation.

[0040] Sample detection: 5 mg of CYP-XBZ and CYP-TG samples prepared in Examples 1 and 2 were accurately weighed and dissolved in 1 mL of ultrapure water. The solutions were allowed to stand at room temperature for 1 hour to ensure complete dissolution. The solutions were filtered through a 0.22 μm microporous membrane. The filtrates were then injected for detection under the chromatographic conditions described above. The number-average molecular weight (Mn) and weight-average molecular weight (Mw) of each elution peak were calculated based on the standard curve. The results are shown in Table 1.

[0041] Table 1. Molecular weight distribution characteristics of polysaccharides from *Dioscorea opposita* and *Dioscorea cirrhosa*.

[0042] As shown in Table 1, the molecular weight distribution range of the two yam polysaccharides is 4kDa~450kDa, and both exhibit 5 characteristic elution peaks. The overall distribution pattern is highly consistent, with only minor differences in the molecular weight of a single component. This indicates that the two have similar polysaccharide molecular chain lengths and hydrodynamic volumes, which meets the molecular weight distribution requirements of claim 3.

[0043] 1.2 Determination of Monosaccharide Composition The monosaccharide composition was determined using high-performance ion chromatography-pulse amperometric detection (HPAEC-PAD). The specific method is as follows: Sample hydrolysis: Accurately weigh 5 mg each of CYP-XBZ and CYP-TG samples and place them in separate ampoules. Add 2 mL of 2 mol / L trifluoroacetic acid (TFA) solution, seal the ampoules, and hydrolyze in an oven at 121 °C for 2 hours. After hydrolysis, cool to room temperature, open the ampoules, transfer the hydrolysate to centrifuge tubes, blow dry with nitrogen to remove excess TFA, add anhydrous methanol and wash repeatedly 3 times, blowing dry each time to completely remove residual TFA. Finally, redissolve the residue with 5 mL of ultrapure water, filter through a 0.22 μm microporous membrane to obtain the sample hydrolysate for later use.

[0044] Chromatographic conditions: ThermoICS 5000+ ion chromatography system, equipped with a quaternary gradient pump and a pulsed amperometric detector (PAD); column: Dionex™ CarboPac™ PA20 anion exchange column (150 mm × 3.0 mm, 10 μm); column temperature: 30 °C; mobile phase A: ultrapure water; mobile phase B: 250 mmol / L sodium hydroxide solution; mobile phase C: 1 mol / L sodium acetate solution, gradient elution; flow rate: 0.5 mL / min; injection volume: 10 μL; gold working electrode; Ag / AgCl reference electrode; four-potential pulsed amperometric detection mode.

[0045] Preparation of standard solutions: Accurately weigh eight monosaccharide reference standards, including D-glucose, D-galactose, and D-mannose, and prepare a 100 μg / mL mixed monosaccharide standard solution with ultrapure water. Quantitatively dilute the solutions to obtain a series of concentrations of standard solutions. Inject the solutions under the chromatographic conditions described above and plot the standard curve.

[0046] Sample testing: The sample hydrolysate was injected and tested under the above chromatographic conditions. The qualitative analysis was performed by comparing the retention time with that of the standard, and the mass percentage of each monosaccharide was calculated quantitatively based on the standard curve. The results are shown in Table 2.

[0047] Table 2 Monosaccharide composition of polysaccharides from *Dioscorea opposita* and *Dioscorea cirrhosa*.

[0048] As shown in Table 2, both yam polysaccharides are neutral heteropolysaccharides mainly composed of D-glucose, with a glucose mass ratio exceeding 96%, which meets the core structural requirements of claims 1 and 6. The only difference between the two is the galactose ratio. Iron stick yam polysaccharide contains trace amounts of mannose, while no mannose was detected in small white yam polysaccharide, which meets the monosaccharide ratio requirement of claim 2.

[0049] 1.3 Spectral Characteristic Analysis -UV-Vis absorption spectroscopy: 100μg / mL aqueous solutions of CYP-XBZ and CYP-TG were prepared respectively. A UV-2600 UV-Vis spectrophotometer was used to perform full wavelength scanning in the wavelength range of 190nm~1100nm. The results showed that both samples showed a characteristic strong absorption peak of polysaccharides at a wavelength of 200nm, no characteristic absorption peak of nucleic acids at a wavelength of 260nm, and only a very weak absorption at a wavelength of 280nm. This indicates that the two polysaccharide samples were free of nucleic acid contamination and contained only trace amounts of binding proteins. The purity was good and met the purity requirements for food and pharmaceutical raw materials.

[0050] - Fourier Transform Infrared Spectroscopy (FT-IR): 1 mg of dried CYP-XBZ and CYP-TG samples were thoroughly ground with 100 mg of spectral-grade KBr, pressed into transparent thin films, and scanned in the wavenumber range of 4000 cm⁻¹ to 400 cm⁻¹ using a Nicoletti S5 Fourier Transform Infrared Spectrometer, with a resolution of 4 cm⁻¹ and 32 scans. The results showed that the infrared peak shapes and positions of the two samples highly overlapped, both exhibiting typical polysaccharide characteristic absorption peaks: the broad and strong peak near 3400 cm⁻¹ was the OH stretching vibration peak, reflecting the abundant hydroxyl groups and hydrogen bonds in the polysaccharide molecule; the weak absorption peak near 2920 cm⁻¹ was the CH stretching vibration peak; the absorption peak near 1630 cm⁻¹ was the bending vibration peak of bound water; and the strong absorption band in the range of 1000 cm⁻¹ to 1150 cm⁻¹ was the COC and CO stretching vibration peak, which are characteristic absorption peaks of pyranose rings and glycosidic bonds. The above results confirm that the two yam polysaccharides have completely identical core functional groups and polysaccharide skeleton structures.

[0051] Experiment Example 2: Verification of the cytotoxic and cardioprotective activities of yam polysaccharides 2.1 Cytotoxicity assay H9c2 rat cardioblasts were injected with 1×10 4 Cells were seeded at a density of 1 cell / well in 96-well cell culture plates and incubated at 37°C, 5% CO2, and saturated humidity for 24 hours. The original culture medium was discarded, and complete culture medium containing CYP-XBZ, CYP-TG, purified polysaccharide of Comparative Example 1, and yam polysaccharide of Comparative Example 2 at final concentrations of 0, 10, 50, 100, 200, 500, and 1000 μg / mL was added to each well. Six replicates were set for each group, and the cells were cultured for another 24 hours. After the culture was completed, 10 μL of LCK-8 reagent was added to each well, and the cells were incubated at 37°C in the dark for 1 hour. The absorbance of each well was measured at 450 nm using a Synergy H1 full-wavelength microplate reader. The relative viability of cells in each group was calculated, and the zero point was corrected by the blank group with only culture medium. The cell viability of the 0 μg / mL drug group was taken as 100%.

[0052] The results showed that the relative survival rate of H9c2 cells was above 95% for both CYP-XBZ and CYP-TG at a concentration as high as 1000 μg / mL, with no significant difference from the blank control group (p>0.05), indicating that neither had any cytotoxicity within the tested concentration range and had excellent biocompatibility. The purified polysaccharide of Comparative Example 1 showed that the cell survival rate decreased to 89.2% and 82.5% at concentrations of 500 μg / mL and 1000 μg / mL, respectively, indicating slight cytotoxicity. The yam polysaccharide of Comparative Example 2 showed that the cell survival rate decreased to 85.3% at a concentration of 200 μg / mL and only 61.7% at a concentration of 1000 μg / mL, with significantly lower safety than the yam polysaccharide of this invention.

[0053] 2.2 Construction of an Oxygen-Glucose Deprivation / Reoxygenation (OGD / R) Cardiomyocyte Injury Model When H9c2 cells reach 80%–90% confluence, they are digested with 0.25% trypsin at a concentration of 2 × 10⁻⁶. 5 Cells were seeded at a density of cells / well in 6-well plates and cultured adherently for 24 hours. Cells were then randomly divided into the following 8 groups, with 3 biological replicates in each group: - Normal control group (Control): Normal DMEM high glucose medium containing 10% FBS was used and cultured continuously in a normal incubator without OGD / R treatment or drug administration; - Model group: OGD / R treatment was performed without drug administration, only an equal volume of blank culture medium was added; - CYP-XBZ low-dose group: OGD / R treatment + 25 μg / mL CYP-XBZ; - High-dose CYP-XBZ group: OGD / R treatment + 100 μg / mL CYP-XBZ; - CYP-TG low-dose group: OGD / R treatment + 25 μg / mL CYP-TG; - High-dose CYP-TG group: OGD / R treatment + 100 μg / mL CYP-TG; -Compound composition group: OGD / R treatment + 100 μg / mL of the 1:1 compound composition of Example 3; - Positive control group: OGD / R treatment + 100μM trimetazidine (first-line clinical cardioprotective drug).

[0054] OGD / R modeling method: The original culture medium of each group of cells was discarded. Except for the normal control group, the other groups were replaced with glucose-free and serum-free DMEM culture medium. The cells were quickly placed in a three-gas anaerobic incubator (95% N2 + 5% CO2, oxygen concentration <0.5%) and cultured at 37°C for 2 hours to complete oxygen-glucose deprivation (OGD). After the culture was completed, the cells were quickly removed and the glucose-free culture medium was discarded. Except for the normal control group and the model group, the other groups were added with complete culture medium containing the corresponding concentration of drug. The model group was added with an equal volume of blank complete culture medium. The cells were placed back in a normal CO2 incubator and cultured at 37°C for 24 hours to complete reoxygenation (R).

[0055] 2.3 Cell viability assay After reoxygenation culture, the cell viability of each group was detected using the CCK-8 assay kit, using the same method as in 2.1. The cell viability of the normal control group was taken as 100%, and the relative cell viability of each group was calculated. The results are shown in Table 3.

[0056] Table 3 Effects of yam polysaccharide on the viability of OGD / R-damaged H9c2 cells (n=6, x±s)

[0057] Note: Compared with the normal control group, **p<0.01; compared with the model group, *p<0.05, **p<0.01; compared with the positive control group, #p>0.05, ##p>0.05.

[0058] As shown in Table 3, compared with the normal control group, the cell viability of the model group was significantly reduced (p<0.01), indicating that OGD / R induced severe cardiomyocyte damage, and the model was successfully constructed. Compared with the model group, both CYP-XBZ and CYP-TG can significantly improve the viability of damaged cardiomyocytes in a dose-dependent manner (p<0.05 or p<0.01), and the cell viability recovery effect of the high-dose group was not significantly different from that of the first-line clinical positive drug trimetazidine (p>0.05). There was no significant difference between the same dose groups of the two yam polysaccharides, and there was also no significant difference between the compound composition group and the single polysaccharide group, confirming that the polysaccharides of *Dioscorea opposita* and *Dioscorea cirrhosa* have equally significant cardioprotective activity, and the combination of the two can also achieve the same effect, fully supporting the core technical solutions of claims 1 and 6.

[0059] 2.4 Detection of markers of myocardial injury and oxidative stress After reoxygenation culture, the culture supernatant of each group of cells was collected, centrifuged at 3000×g for 10 minutes at 4℃, and the supernatant was used to detect the levels of creatine kinase isoenzyme (CK-MB) and cardiac troponin T (cTnT), markers of cardiomyocyte damage, according to the kit instructions. Cells from each group were collected, and pre-cooled RIPA lysis buffer was added to extract total protein. The total protein concentration was determined using the BCA kit. The level of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a marker of oxidative DNA damage, in the cell lysate was detected according to the kit instructions. The results were standardized to the total protein concentration and are shown in Table 4.

[0060] Table 4. Effects of yam polysaccharides on myocardial injury and oxidative stress markers (n=3, x±s)

[0061] Note: Compared with the normal control group, **p<0.01; compared with the model group, ##p<0.01.

[0062] As shown in Table 4, compared with the normal control group, the levels of CK-MB, cTnT, and 8-OHdG in the model group were significantly increased (p<0.01), indicating that OGD / R induced severe myocardial cell membrane damage and oxidative DNA damage. Compared with the model group, both the high-dose CYP-XBZ and CYP-TG groups significantly reduced the levels of the above three markers (p<0.01), with effects comparable to the positive control drug trimetazidine, and no significant difference between the two. The above results confirm that the *Dioscorea opposita* polysaccharide of the present invention can exert a cardioprotective effect by reducing myocardial cell membrane damage and alleviating myocardial cell oxidative stress damage, fully supporting the functional limitations of claims 7 and 8.

[0063] Experiment 3: Verification of the molecular mechanism of the cardioprotective effect of yam polysaccharide 3.1 Combined Transcriptomics and Proteomics Analysis Cells from the normal control group, model group, high-dose CYP-XBZ group, and high-dose CYP-TG group were collected, with three biological replicates for each group. Transcriptome sequencing and quantitative proteomics analysis were performed on each group. - Transcriptomics analysis: Total RNA was extracted from cells in each group using the Trizol method. After agarose gel electrophoresis and testing for RNA integrity and purity using an Agilent 2100 bioanalyzer, cDNA libraries were constructed and high-throughput sequencing was performed using the Illumina NovaSeq 6000 platform. After quality control and alignment to the rat reference genome, differentially expressed genes (DEGs) were analyzed using DESeq2 software. The screening criteria were |log2FC|>1 and corrected p-value (FDR)<0.05. KEGG pathway enrichment analysis and gene set enrichment analysis (GSEA) were performed using clusterProfiler software.

[0064] The results showed that, compared with the model group, the CYP-XBZ treatment group identified 4514 differentially expressed genes (2929 upregulated and 1585 downregulated), and the CYP-TG treatment group identified 3900 differentially expressed genes (1588 upregulated and 2312 downregulated). The two groups shared 2884 differentially expressed genes. KEGG enrichment analysis of the shared genes revealed that the core enriched pathways were stress- and inflammation-related pathways such as the MAPK signaling pathway, NF-κB signaling pathway, PI3K-Akt signaling pathway, and Ras signaling pathway. Among these, the enrichment of the MAPK and NF-κB signaling pathways was the most significant (p<0.001). GSEA analysis further confirmed that after treatment with yam polysaccharide, the gene sets related to the MAPK and NF-κB signaling pathways showed significant negative enrichment, indicating that both treatments could significantly inhibit the activation of these two pathways.

[0065] - Proteomics analysis: Total protein was extracted from cells in each group using SDS lysis. After BCA quantification and trypsin digestion, TMT labeling was performed. The labeled peptides were then mixed and fractionated by high-pH reversed-phase chromatography, and detected by LC-MS / MS using a Thermo Orbitrap FusionLumos mass spectrometer. The mass spectrometry data were compared with the rat UniProt database using ProteomeDiscoverer 2.4 software for protein identification and quantification. The screening criteria for differentially expressed proteins (DEPs) were |log2FC|>0.26 and FDR<0.05. KEGG pathway enrichment analysis and protein-protein interaction (PPI) network construction were performed.

[0066] The results showed that, compared with the model group, the CYP-XBZ treatment group identified 979 differentially expressed proteins (451 upregulated and 528 downregulated), while the CYP-TG treatment group identified 824 differentially expressed proteins (447 upregulated and 377 downregulated). The two groups shared 369 differentially expressed proteins. KEGG enrichment analysis of the shared proteins further highlighted the MAPK signaling pathway as the core regulatory pathway (p<0.001). PPI network analysis showed that MAPK1 (p38MAPK) was the core node protein in the network, exhibiting the highest degree centrality.

[0067] The combined transcriptomics and proteomics analysis results confirmed that both *Dioscorea opposita* polysaccharide and *Dioscorea cirrhosa* polysaccharide exert cardioprotective effects through highly consistent transcriptional and protein regulatory patterns, with the core regulatory targets being the MAPK and NF-κB signaling pathways.

[0068] 3.2 Western blot verification of core signaling pathways Total protein was extracted from cells in each group, and RIPA lysis buffer containing protease inhibitors and phosphatase inhibitors was added. The cells were lysed on ice for 30 minutes, centrifuged at 12000×g for 15 minutes at 4°C, and the supernatant was collected. The total protein concentration was determined using a BCA kit. Equal volumes of protein samples were subjected to SDS-PAGE gel electrophoresis. After electrophoresis, the proteins were electrotransferred onto a PVDF membrane. The membrane was blocked with 5% skim milk at room temperature for 2 hours, and then primary antibodies diluted 1:1000 (MyD88, p-p38, p38, p-p65, p65, CEBP) were added. B, β-actin), incubated overnight on a shaker at 4°C; washed 3 times with TBST for 10 minutes each time, added HRP-labeled secondary antibody diluted 1:5000, and incubated at room temperature for 1 hour; after washing 3 times with TBST, the protein was developed using an ECL chemiluminescence kit, exposed and photographed using a ChemiDocXRS+ imaging system, and the gray values ​​of the bands were quantitatively analyzed using ImageJ software. β-actin was used as an internal control to calculate the relative expression level of the target protein. Phosphorylated protein was expressed as the gray ratio of the phosphorylated band to the total protein band.

[0069] The results show: 1. Compared with the normal control group, the relative expression levels of MyD88 and CEBPB proteins in the model group were significantly increased, and the phosphorylation levels of p38MAPK and NF-κBp65 (p-p38 / p38, p-p65 / p65) were significantly increased (p<0.01), confirming that OGD / R induced significant activation of the MyD88-mediated MAPK / NF-κB signaling pathway; 2. Compared with the model group, both the high-dose CYP-XBZ and CYP-TG groups significantly downregulated the protein expression levels of MyD88 and CEBPB, and significantly reduced the phosphorylation levels of p38MAPK and NF-κBp65 (p<0.01), with no significant difference in their regulatory effects.

[0070] The above-mentioned Western blot verification results clearly confirm that the yam polysaccharide of the present invention inhibits the phosphorylation of p38MAPK and NF-κBp65 by downregulating MyD88 protein expression, thereby blocking the activation of the MyD88-mediated MAPK / NF-κB signaling pathway, inhibiting the inflammatory cascade and oxidative stress of cardiomyocytes, and finally exerts a cardioprotective effect, which fully supports the mechanism of action defined in claim 9.

[0071] Experimental Example 4: Stability of Preparation Process and Pilot-Scale Verification To verify the industrial applicability of the preparation process of this invention, three batches of pilot-scale production were carried out. The feed amount for each batch was 10 kg of dried yam powder. The production was carried out according to the process parameters of Example 1. At the same time, the key process parameters were adjusted within a reasonable range to verify the stability of the process. The specific parameters and results are shown in Table 5.

[0072] Table 5. Results of stability verification of pilot-scale process

[0073] As shown in Table 5, when the process conditions are adjusted within a reasonable parameter range, there are no significant differences in the extraction yield, monosaccharide composition, and cardioprotective activity of the three batches of pilot-scale products. This confirms that the preparation process parameters of the present invention have a wide range, strong stability, and good repeatability, and are fully adaptable to industrial-scale production, ensuring the quality and activity stability of different batches of products.

Claims

1. A polysaccharide composition of *Dioscorea opposita* with cardioprotective effects, characterized in that, The active ingredient of the composition is yam polysaccharide; the yam polysaccharide is selected from yam polysaccharide of *Dioscorea opposita*, or a combination of yam polysaccharide of *Dioscorea opposita* and yam polysaccharide of *Dioscorea cirrhosa*; the yam polysaccharide is a neutral heteropolysaccharide, and its monosaccharide composition is mainly glucose, which accounts for more than 96% of the total monosaccharide mass.

2. The composition according to claim 1, characterized in that, The monosaccharide composition of the *Dioscorea opposita* polysaccharide is as follows: glucose accounts for 96.8% to 97.4% of the total monosaccharide mass, galactose accounts for 2.2% to 2.6% of the total monosaccharide mass, and mannose is not present. The monosaccharide composition of the *Dioscorea cirrhosa* polysaccharide is as follows: glucose accounts for 96.8% to 97.4% of the total monosaccharide mass, galactose accounts for 2.2% to 2.6% of the total monosaccharide mass, and mannose accounts for 1.0% of the total monosaccharide mass.

3. The composition according to claim 1, characterized in that, The molecular weight distribution range of the yam polysaccharide is 4kDa~450kDa, and it has 5 molecular weight distribution components, wherein: the number average molecular weights of the 5 components of the *Dioscorea opposita* polysaccharide are 370921Da, 172366Da, 55852Da, 12308Da, and 4984Da, respectively; and the number average molecular weights of the 5 components of the *Dioscorea cirrhosa* polysaccharide are 405880Da, 166687Da, 61314Da, 10746Da, and 4836Da, respectively.

4. The composition according to claim 1, characterized in that, The polysaccharide from the white-mouthed yam was prepared through the following steps: S1 defatting pretreatment: After washing, slicing, drying and crushing the tubers of small white yam, they were extracted by reflux with a 70% ethanol solution, and the residue was collected after filtration. S2 hot water extraction: Add distilled water to the filter residue obtained in S1 at a material-to-liquid ratio of 1:10 g / mL, reflux extract twice, 2 hours each time, combine the water extracts and concentrate under reduced pressure to obtain concentrated liquid. S3 Alcohol precipitation and drying: Add anhydrous ethanol to the concentrate until the final volume fraction of ethanol is 70%, let stand overnight at 4°C, collect the precipitate by centrifugation, wash the precipitate with anhydrous ethanol and freeze dry to obtain the polysaccharide of yam. The preparation method of the polysaccharide of Dioscorea opposita is the same as the above steps, except that the raw material is replaced with Dioscorea opposita tuber.

5. The composition according to claim 1, characterized in that, The composition is a pharmaceutical, health food, functional food, or dietary supplement; when the composition is a pharmaceutical, it also contains pharmaceutically acceptable excipients; when the composition is a health food, functional food, or dietary supplement, it also contains food-acceptable excipients; the active ingredient of the composition is yam polysaccharide.

6. The application of *Dioscorea opposita* polysaccharide in the preparation of products with cardioprotective effects, characterized in that... The yam polysaccharide is selected from Xiaobaizui yam polysaccharide, or a combination of Xiaobaizui yam polysaccharide and Tiegun yam polysaccharide; the Xiaobaizui yam polysaccharide is a neutral heteropolysaccharide, and its monosaccharide composition is mainly glucose, which accounts for more than 96% of the total monosaccharide mass.

7. The application according to claim 6, characterized in that, The cardioprotective effect is the protective effect of yam polysaccharide against myocardial ischemia-reperfusion injury, including at least one of improving myocardial cell vitality, reducing myocardial cell membrane damage, and alleviating myocardial cell oxidative stress injury.

8. The application according to claim 7, characterized in that, The reduction of myocardial cell membrane damage is achieved by yam polysaccharide reducing the release levels of creatine kinase isoenzyme CK-MB and cardiac troponin TcTnT; the relief of myocardial cell oxidative stress damage is achieved by yam polysaccharide reducing the level of 8-hydroxy-2'-deoxyguanosine 8-OHdG, a marker of oxidative DNA damage.

9. The application according to claim 6, characterized in that, The polysaccharide from the Chinese yam exerts its cardioprotective effect by downregulating MyD88 protein expression and inhibiting phosphorylation of p38MAPK and NF-κBp65, thereby regulating the MyD88-mediated MAPK / NF-κB signaling pathway.

10. The application according to claim 6, characterized in that, The product is any one of pharmaceuticals, health foods, functional foods, or dietary supplements, and the core active ingredient of the product is yam polysaccharide.

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