Antibacterial and antioxidant peach gum polysaccharide as well as preparation method and application thereof

Abstract

The invention discloses antibacterial and antioxidant peach gum polysaccharide as well as a preparation method and application thereof, and belongs to the technical field of natural high polymer materials, the preparation method comprises the following steps: under the condition of an initiator, peach gum polysaccharide and glycidyl methacrylate are subjected to graft polymerization reaction in water, and epoxidized peach gum polysaccharide is prepared; and dissolving the epoxidized peach gum polysaccharide and sodium polysulfide in water, carrying out gradient temperature reaction, and then sequentially carrying out dialysis and drying to prepare the antibacterial and antioxidant peach gum polysaccharide. The prepared antibacterial and antioxidant peach gum polysaccharide retains excellent hydrophilicity and biocompatibility of natural peach gum polysaccharide, sulfur chains are introduced through accurate molecular structure modification, the antibacterial and antioxidant performance of the peach gum polysaccharide is remarkably improved, the peach gum polysaccharide has wide application prospects in the fields of food, cosmetics, biological medicine and the like, and the antibacterial and antioxidant peach gum polysaccharide can be widely applied to the fields of food, cosmetics, biological medicine and the like. Development and utilization of natural peach gum resources are promoted, and the application range of peach gum polysaccharide is expanded; in addition, the method adopts a water phase system, is safe and environment-friendly, has no organic solvent residue risk, is mild in reaction condition and low in cost, and is easy for large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of natural polymer materials technology, and particularly relates to an antibacterial and antioxidant peach gum polysaccharide, its preparation method and application. Background Technology

[0002] Peach gum polysaccharide is the main component extracted from the natural gum secreted by peach trees. As a natural polymer material, it has attracted widespread attention in various fields such as food, medicine, and cosmetics due to its excellent water solubility, good biocompatibility, and biodegradability. Its natural source and environmental friendliness give it a unique advantage in the development of green materials. However, despite its many excellent properties, peach gum polysaccharide still has significant drawbacks in practical applications. Unmodified natural peach gum polysaccharide lacks intrinsic antibacterial and antioxidant activity and is prone to bacterial growth in humid environments or aqueous solutions. This not only affects its storage stability but may also adversely affect the safety and functional performance of the final product. In addition, peach gum polysaccharide may lose its structural integrity due to microbial degradation during long-term use, further limiting its practicality in demanding application scenarios.

[0003] Currently, most antibacterial and antioxidant materials on the market rely on chemically synthesized antibacterial agents or antioxidants. While these chemicals can meet antibacterial and antioxidant requirements to some extent, their potential toxic side effects and environmental pollution are increasingly concerning. Some studies have shown that long-term exposure to certain chemically synthesized additives may have adverse effects on human health and even lead to the emergence of drug-resistant strains, posing risks to the ecological environment and public health.

[0004] Furthermore, although some studies have attempted to enhance the functional properties of natural polysaccharides through chemical modification, such as using carboxymethylation, sulfation, and acetylation to improve solubility or introduce active groups, these methods still face many challenges in practical applications. On the one hand, these modification methods often fail to simultaneously impart effective antibacterial and antioxidant properties to polysaccharide materials; on the other hand, most modification processes are complex and require harsh reaction conditions, resulting in high production costs and limiting their feasibility for large-scale application. Simultaneously, some modification processes may introduce toxic reagents or residues, affecting the biosafety and environmental performance of the final product.

[0005] Therefore, developing a green, environmentally friendly, simple, and cost-effective method for modifying peach gum polysaccharides, while retaining the excellent properties of natural polysaccharides, has become a pressing technical challenge in the field of natural polymer materials. This is also key to further expanding the application of peach gum polysaccharides in high-value-added fields such as food preservation, cosmetic formulation, and biopharmaceutical materials. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes an antibacterial and antioxidant peach gum polysaccharide, its preparation method, and its applications.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for preparing antibacterial and antioxidant peach gum polysaccharide includes the following steps:

[0009] Under initiator conditions, peach gum polysaccharide and glycidyl methacrylate undergo a graft polymerization reaction in water to prepare epoxidized peach gum polysaccharide;

[0010] The epoxidized peach gum polysaccharide was dissolved in water with sodium polysulfide and subjected to a gradient temperature reaction. Then, it was dialyzed and dried sequentially to prepare the antibacterial and antioxidant peach gum polysaccharide.

[0011] Beneficial Effects: This invention provides a highly efficient and environmentally friendly method for preparing antibacterial and antioxidant peach gum polysaccharides. Through a two-step chemical modification process, the structure and function of natural peach gum polysaccharides are modified and enhanced. The entire preparation process consists of two main stages: the first stage involves graft polymerization of peach gum polysaccharides with glycidyl methacrylate in an aqueous phase in the presence of an initiator to generate epoxidized peach gum polysaccharides; the second stage involves a gradient temperature reaction of the epoxidized product with a self-made sodium polysulfide solution, followed by post-treatment steps such as dialysis and drying to obtain the target product. This method is not only simple and uses mild reaction conditions, but also utilizes an aqueous phase system throughout, avoiding the use of organic solvents, thus possessing significant green chemistry implications and promising industrial application prospects.

[0012] Optionally, the initiator is a persulfate.

[0013] Furthermore, the persulfate is at least one of ammonium persulfate, potassium persulfate, or sodium persulfate.

[0014] Optionally, the molecular weight of the peach gum polysaccharide is 3000-200000 Da.

[0015] Optionally, the mass ratio of the peach gum polysaccharide, initiator, water and glycidyl methacrylate is 1:(0.01-0.1):(20-100):(1-3).

[0016] Optionally, the graft polymerization reaction is carried out at 35–65°C for 1–3 hours.

[0017] Beneficial Effects: This invention selects persulfates (such as ammonium persulfate, potassium persulfate, or sodium persulfate) as free radical initiators to stimulate a free radical grafting reaction between glycidyl methacrylate and the active hydrogen atoms on the gum arabic polysaccharide molecular chain at 35–65°C. By controlling the mass ratio of gum arabic polysaccharide, initiator, water, and glycidyl methacrylate (1:1.5–4:30–100:1–3), the homogeneity of the reaction system and grafting efficiency are ensured, thereby introducing a large number of epoxy groups into the gum arabic polysaccharide backbone to form epoxidized gum arabic polysaccharide. The introduction of this structure provides reaction sites for the subsequent introduction of thiol groups and is a key step in achieving functionalization modification.

[0018] Optionally, the preparation process of the sodium polysulfide is as follows: sulfur powder is mixed with sodium sulfide or sodium hydroxide, and the mixture is stirred and reacted at 30-90°C for 1-3 hours to obtain the sodium polysulfide.

[0019] Furthermore, the mass ratio of sulfur powder to sodium sulfide is 1:(1.5-4); or,

[0020] The mass ratio of sulfur powder to sodium hydroxide is 1:(1.2-3).

[0021] Beneficial effects: This invention prepares sodium polysulfide solution in situ by reacting sulfur powder with sodium sulfide or sodium hydroxide at 30–90°C for 1–3 hours. By controlling the mass ratio of sulfur powder to sodium sulfide or sodium hydroxide (1:1.5–4 or 1:1.2–3, respectively), the valence state and structure of the sulfides can be effectively adjusted to form a reaction system with active thiol groups.

[0022] Optionally, the mass ratio of the epoxidized gum polysaccharide, sodium polysulfide, and water is 1:(0.75-1.5):(20-100).

[0023] Optionally, the step temperature reaction conditions are as follows: first, stir the reaction at 40-70°C for 1-3 hours, and then move it to room temperature to continue the reaction for 3 hours.

[0024] Beneficial effects: The high-temperature stage (40–70°C) defined in this invention can significantly increase the reaction rate, rapidly consume highly reactive epoxy groups, and improve efficiency. Simultaneously, limiting the high-temperature duration effectively avoids side reactions such as sodium polysulfide decomposition, excessive cross-linking, or degradation, ensuring reaction selectivity and product stability. The subsequent room-temperature stage promotes the full and complete reaction of remaining groups, optimizes cross-linking density and network uniformity, and maintains the activity of sodium polysulfide. Ultimately, it achieves an optimized balance between reaction efficiency and product structure / performance while saving energy.

[0025] An antibacterial and antioxidant peach gum polysaccharide was prepared by the above-mentioned preparation method.

[0026] The above-mentioned antibacterial and antioxidant peach gum polysaccharide has applications in the preparation of food, cosmetics, and biomedicine.

[0027] Beneficial Effects: The antibacterial and antioxidant peach gum polysaccharide disclosed in this invention not only achieves precise modification of the molecular structure of peach gum polysaccharide, but also significantly enhances its antibacterial and antioxidant properties. The resulting antibacterial and antioxidant peach gum polysaccharide exhibits good water solubility and biocompatibility, and demonstrates excellent free radical scavenging ability and inhibitory effects on common pathogenic bacteria such as Staphylococcus aureus, showing broad application potential in food preservation, cosmetic formulation, and biopharmaceutical materials.

[0028] Compared with the prior art, the present invention has the following advantages and technical effects:

[0029] In terms of preparation process, this invention uses an aqueous phase system throughout, eliminating the risk of residual organic solvents and improving production safety and environmental performance. Meanwhile, the synthesis process is simple, the reaction conditions are mild, and the production cost is low, demonstrating high feasibility for large-scale production.

[0030] In terms of product performance, the peach gum polysaccharide prepared by this invention not only retains the excellent hydrophilicity and biocompatibility of natural peach gum polysaccharide, but also significantly enhances its antibacterial and antioxidant properties through precise modification of its molecular structure. Tests have shown that the peach gum polysaccharide prepared by this invention exhibits excellent inhibitory effects against Staphylococcus aureus, while also demonstrating outstanding ability to scavenge free radicals.

[0031] Given the aforementioned superior properties, the antibacterial and antioxidant peach gum polysaccharide of the present invention shows broad application prospects in multiple fields such as food, cosmetics, and biomedicine, and is expected to provide related industries with a novel, efficient, safe, and environmentally friendly natural polymer material. Attached Figure Description

[0032] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0033] Figure 1 The infrared spectrum of the antibacterial and antioxidant peach gum polysaccharide prepared in Example 1 of this invention;

[0034] Figure 2 The X-ray photoelectron spectroscopy (XPS) spectrum of the antibacterial and antioxidant peach gum polysaccharide prepared in Example 1 of this invention is shown below.

[0035] Figure 3 Bar chart showing the cell viability of antibacterial and antioxidant peach gum polysaccharide prepared in Example 1 of the present invention co-cultured with L929 cells or B16 cells at different concentrations;

[0036] Figure 4 The graph shows the scavenging efficiency of the antibacterial and antioxidant peach gum polysaccharide prepared in Example 1 of this invention against 2,2-adiazonium-bis(3-ethyl-benzothiazole-6-sulfonic acid) diammonium salt (ABTS) free radicals at different concentrations.

[0037] Figure 5 The antibacterial and antioxidant peach gum polysaccharide prepared in Example 2 of this invention has bactericidal effects on Staphylococcus aureus at different concentrations.

[0038] Figure 6 Scanning electron microscope images of the antibacterial and antioxidant gum polysaccharide prepared in Example 2 before (a) and after (b) treatment for Staphylococcus aureus;

[0039] Figure 7 The graph shows the scavenging efficiency of the antibacterial and antioxidant peach gum polysaccharide prepared in Example 3 of this invention against 2,2-adiazonium-bis(3-ethyl-benzothiazole-6-sulfonic acid) diammonium salt (ABTS) free radicals at different concentrations.

[0040] Figure 8 Images show the antibacterial effect of the antibacterial and antioxidant peach gum polysaccharide prepared in Example 3; the left image is a photo of the positive control group, and the right image is a photo of Staphylococcus aureus after treatment with the antibacterial and antioxidant peach gum polysaccharide. Detailed Implementation

[0041] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0042] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0043] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0044] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0045] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0046] This invention discloses an antibacterial and antioxidant peach gum polysaccharide and its preparation method, comprising the following steps:

[0047] (1) Dissolve 1 part by weight of water-soluble peach gum polysaccharide and 0.01 to 0.1 parts by weight of persulfate in 30 to 100 parts by weight of water, stir at 50 to 65°C for 30 to 60 minutes under an inert gas atmosphere, and then add 1 to 3 parts by weight of glycidyl methacrylate dropwise to the mixture of peach gum polysaccharide and persulfate. After the addition is complete, react at 35 to 65°C for 1 to 3 hours to obtain epoxidized peach gum polysaccharide.

[0048] (2) Method 1: Mix 1 part by weight of sulfur powder with 1.5 to 4 parts by weight of sodium sulfide, stir at 30 to 90°C for 1 to 3 hours to produce sodium sulfide;

[0049] Method 2: Mix 1 part by weight of sulfur powder with 1.2 to 3 parts by weight of sodium hydroxide, and stir at 30 to 90°C for 1 to 3 hours to prepare sodium polysulfide;

[0050] (3) Add 1 part by weight of the epoxidized peach gum polysaccharide obtained in step (1) and 0.75 to 1.5 parts by weight of the sodium polysulfide obtained in step (2) to 20 to 100 parts by weight of water to dissolve. After stirring the mixture at 40 to 70°C for 1 to 3 hours, move it to room temperature and continue the reaction for 3 hours. Then, dialyze it with deionized water and vacuum dry it to obtain antibacterial and antioxidant peach gum polysaccharide.

[0051] In some alternative embodiments, the molecular weight of the water-soluble peach gum polysaccharide is 3,000 to 200,000 Da.

[0052] In some alternative embodiments, the persulfate in step (1) is one of ammonium persulfate, potassium persulfate, or sodium persulfate.

[0053] This invention also provides an antibacterial and antioxidant peach gum polysaccharide prepared according to the above preparation method; this peach gum polysaccharide exhibits a significant antibacterial effect against Staphylococcus aureus at a concentration of 0.31 mg / mL. Furthermore, it can effectively scavenge 2,2-adiazonium-bis(3-ethyl-benzothiazole-6-sulfonic acid) diammonium salt (ABTS) free radicals, fully demonstrating its excellent antioxidant properties.

[0054] In summary, this invention proposes a two-step aqueous phase controllable functionalization scheme, achieving a technological breakthrough through the following innovative design:

[0055] 1) Persulfate was used to initiate the graft polymerization of glycidyl methacrylate, introducing epoxy groups onto the gum polysaccharide macromolecules. By precisely controlling the temperature (50-65℃) under inert gas protection, the occurrence of side reactions was effectively suppressed.

[0056] 2) The epoxidized gum polysaccharide is reacted with sodium polysulfide to introduce sulfur chains into the gum polysaccharide macromolecule. Then, the reaction is carried out through a gradient temperature to avoid cross-linking of sulfur chains and at the same time ensure the hydrophilicity of the product.

[0057] 3) The entire preparation process of this invention adopts an aqueous reaction system, which eliminates the risk of residual organic solvents, significantly improves the safety and environmental friendliness of the preparation process, and the final antibacterial and antioxidant peach gum polysaccharide not only retains the hydrophilicity of natural peach gum polysaccharide, but also achieves synergistic enhancement of antibacterial and antioxidant functions through the introduction of sulfur chains, providing a new approach for the development of natural polysaccharide-based antibacterial and antioxidant materials.

[0058] Unless otherwise specified, "room temperature" in this invention refers to 20-30℃.

[0059] Unless otherwise specified, the term "parts" in this invention refers to parts by weight.

[0060] All raw materials used in this invention were purchased from the market.

[0061] Water-soluble peach gum polysaccharide was purchased from Changsha Houcheng Nanomaterials Technology Co., Ltd.

[0062] Glycidyl methacrylate is an ester compound with the molecular formula C7H. 10 O3, also known as 2,3-epoxypropyl methacrylate, or GMA for short, is a colorless and transparent liquid.

[0063] In a specific embodiment provided by the present invention, the dialysis involved is performed using a dialysis bag with a molecular weight cutoff of 1800 Da, and dialysis in deionized water for 24 hours.

[0064] The technical solution of the present invention will be further illustrated by the following embodiments.

[0065] Example 1

[0066] A method for preparing antibacterial and antioxidant peach gum polysaccharide, comprising the following steps:

[0067] (1) Dissolve 2g of water-soluble peach gum polysaccharide with a molecular weight of 30000Da and 0.1g of potassium persulfate in 50g of water, stir at 60℃ for 45min under argon atmosphere, then add 2g of glycidyl methacrylate dropwise to the mixture of peach gum polysaccharide and persulfate, and react at 55℃ for 3h after the addition is complete to obtain epoxidized peach gum polysaccharide;

[0068] (2) Mix 2g of sulfur powder with 4g of sodium hydroxide and stir at 80°C for 2 hours to prepare sodium polysulfide;

[0069] (3) Add 2g of epoxidized peach gum polysaccharide obtained in step (1) and 2g of sodium polysulfide obtained in step (2) to 50g of water to dissolve. After stirring the mixture at 50℃ for 3h, move it to room temperature and continue the reaction for 3h. Then, dialyze with deionized water and vacuum dry to obtain antibacterial and antioxidant peach gum polysaccharide.

[0070] Figure 1 The infrared spectrum of the antibacterial and antioxidant peach gum polysaccharide prepared in Example 1 of this invention.

[0071] Figure 2 The image shows the X-ray photoelectron spectroscopy (XPS) spectrum of the antibacterial and antioxidant peach gum polysaccharide prepared in Example 1 of this invention. Figure 1 and Figure 2 As can be seen, Example 1 of the present invention successfully prepared a macromolecular peach gum polysaccharide containing sulfur chains.

[0072] Figure 3 The bar graph shows the cell viability of the antibacterial and antioxidant gum polysaccharide prepared in Example 1 of this invention after co-culturing L929 cells or B16 cells at different concentrations in an incubator at 37°C and 5% CO2 for 24 hours. The results were determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Figure 3 It can be seen that the antibacterial and antioxidant peach gum polysaccharide prepared in Example 1 of the present invention has low cytotoxicity and good biocompatibility.

[0073] Figure 4This is a graph showing the scavenging efficiency of the antibacterial and antioxidant gum polysaccharide prepared in Example 1 of this invention against 2,2-adiazonium-bis(3-ethyl-benzothiazole-6-sulfonic acid) diammonium salt (ABTS) free radicals at different concentrations. The experimental procedure was as follows: 2.85 mL of ABTS free radical solution was taken and mixed with an appropriate amount of sample solution, then diluted to 3.00 mL with deionized water to ensure a constant total volume. Simultaneously, the concentration of the sample in the mixed system was precisely controlled at 0, 100, 200, 300, 400, and 500 μg / mL. The mixed solution was reacted at 734 nm in the dark for 30 min, and the absorbance change was measured to evaluate the scavenging ability of the sample against ABTS free radicals. Figure 4 It can be seen that the antibacterial and antioxidant peach gum polysaccharide prepared in Example 1 of the present invention achieved a scavenging efficiency of 93% against ABTS free radicals at a concentration of 100 μg / mL. Subsequently, as the concentration increased, the scavenging efficiency of the antibacterial and antioxidant peach gum polysaccharide against ABTS free radicals approached 99%.

[0074] Example 2

[0075] A method for preparing antibacterial and antioxidant peach gum polysaccharide, comprising the following steps:

[0076] (1) Dissolve 1g of water-soluble peach gum polysaccharide with a molecular weight of 25000Da and 0.05g of potassium persulfate in 30g of water, stir at 65℃ for 30min under argon atmosphere, then add 3g of glycidyl methacrylate dropwise to the mixture of peach gum polysaccharide and persulfate, and react at 60℃ for 2h after the addition is complete to obtain epoxidized peach gum polysaccharide;

[0077] (2) Mix 1g of sulfur powder with 3g of sodium hydroxide and stir at 50°C for 3h to prepare sodium polysulfide;

[0078] (3) Add 1g of epoxidized peach gum polysaccharide obtained in step (1) and 1.5g of sodium polysulfide obtained in step (2) to 100g of water to dissolve. After stirring the mixture at 55℃ for 2h, move it to room temperature and continue the reaction for 3h. Then, dialyze with deionized water and vacuum dry to obtain antibacterial and antioxidant peach gum polysaccharide.

[0079] Figure 5 This invention presents the bactericidal results of the antibacterial and antioxidant peach gum polysaccharide prepared in Example 2 of this invention against Staphylococcus aureus at different concentrations. The antibacterial effect was evaluated based on the number of colonies using the plate coating method. The experimental steps are as follows: 1 mL of antibacterial and antioxidant peach gum polysaccharide solutions of different concentrations were mixed with 1 mL of solution containing 6 × 10⁻⁶ g / mL of saturated gum. 5 CFU of Staphylococcus aureus culture was mixed and incubated together at 37°C for 6 hours. After incubation, 100 μL of the mixture was spread onto the surface of LB-Agar solid medium and incubated at 37°C for another 18 hours. The results were then photographed and recorded. Figure 5 It can be seen that the antibacterial and antioxidant peach gum polysaccharide prepared in Example 2 showed a significant bactericidal effect against Staphylococcus aureus at a concentration of 0.31 mg / mL, and the bactericidal effect became more prominent as the concentration increased.

[0080] Figure 6 Scanning electron microscope (SEM) images of the antibacterial and antioxidant gum arabic polysaccharide prepared in Example 2 before (a) and after (b) treatment with Staphylococcus aureus. The treatment steps are as follows: 1 mL of an antibacterial and antioxidant gum arabic polysaccharide solution with a concentration of 2.5 mg / mL was mixed with 1 mL of a solution containing 6 × 10⁻⁶ mg / mL gum arabic polysaccharide. 5 CFU of Staphylococcus aureus bacterial suspension was mixed and incubated together in a 37°C incubator for 6 hours. The mixture was then used as a sample for scanning electron microscopy observation. Figure 6 It can be seen that after treating Staphylococcus aureus with the antibacterial and antioxidant peach gum polysaccharide prepared in Example 2, the spherical structure of the bacteria changed significantly, indicating that the antibacterial and antioxidant peach gum polysaccharide prepared in Example 2 can cause structural damage to Staphylococcus aureus, thereby achieving a bactericidal effect.

[0081] Example 3

[0082] A method for preparing antibacterial and antioxidant peach gum polysaccharide, comprising the following steps:

[0083] (1) Dissolve 1g of water-soluble peach gum polysaccharide with a molecular weight of 200000Da and 0.1g of ammonium persulfate in 100g of water, stir at 50℃ for 60min under nitrogen atmosphere, then add 1g of glycidyl methacrylate dropwise to the mixture of peach gum polysaccharide and persulfate, and react at 35℃ for 3h after the addition is complete to obtain epoxidized peach gum polysaccharide;

[0084] (2) Mix 1g of sulfur powder with 4g of sodium sulfide and stir at 90°C for 1h to prepare sodium polysulfide;

[0085] (3) Add 1g of epoxidized peach gum polysaccharide obtained in step (1) and 1.2g of sodium polysulfide obtained in step (2) to 60g of water to dissolve. After stirring the mixture at 70℃ for 1.5h, move it to room temperature and continue the reaction for 3h. Then, dialyze it with deionized water and vacuum dry it to obtain antibacterial and antioxidant peach gum polysaccharide.

[0086] Figure 7This is a graph showing the scavenging efficiency of the antibacterial and antioxidant gum polysaccharide prepared in Example 3 of this invention against 2,2-adiazonium-bis(3-ethyl-benzothiazole-6-sulfonic acid) diammonium salt (ABTS) free radicals at different concentrations. In the experiment, 2.85 mL of ABTS free radical solution was taken and mixed with an appropriate amount of sample solution, then diluted to 3.00 mL with deionized water to ensure a constant total volume. The final concentration of the sample in the mixed system was precisely controlled at 0, 25, 50, 75, 100, 150, 200, and 250 μg / mL. The mixed solution was reacted at 734 nm in the dark for 30 min, and the absorbance change was measured to evaluate the scavenging ability of the sample against ABTS free radicals. Figure 7 It can be seen that when the concentration of antibacterial and antioxidant peach gum polysaccharide reaches 150 μg / mL, its scavenging efficiency against ABTS free radicals is as high as 98%, indicating that it has a good free radical scavenging effect.

[0087] Figure 8 This study demonstrates the antibacterial and antioxidant peach gum polysaccharide prepared in Example 3 against Staphylococcus aureus. The left image shows the positive control group, and the right image shows Staphylococcus aureus treated with the antibacterial and antioxidant peach gum polysaccharide. The antibacterial effect was evaluated using the plate coating method based on the number of colonies. The experimental procedure was as follows: 1 mL of a 2 mg / mL antibacterial and antioxidant peach gum polysaccharide solution was mixed with 1 mL of a solution containing 6 × 10⁻⁶... 5 CFU of Staphylococcus aureus culture was mixed to obtain a final concentration of 1 mg / mL of antibacterial and antioxidant gum arabic polysaccharide, followed by co-incubation at 37°C for 6 hours. After incubation, 100 μL of the mixture was spread onto the surface of LB-Agar solid medium and incubated at 37°C for another 18 hours. The results were then photographed and recorded. Figure 8 As can be seen, a large number of colonies grew on the surface of the culture medium in the positive control group, while almost no Staphylococcus aureus colonies were visible on the culture medium treated with antibacterial and antioxidant peach gum polysaccharide. This result fully demonstrates that the antibacterial and antioxidant peach gum polysaccharide prepared in this invention has good antibacterial activity against Staphylococcus aureus.

[0088] Example 4

[0089] A method for preparing antibacterial and antioxidant peach gum polysaccharide, comprising the following steps:

[0090] (1) Dissolve 1g of water-soluble peach gum polysaccharide with a molecular weight of 3000Da and 0.01g of potassium persulfate in 30g of water, stir at 50℃ for 60min under argon atmosphere, then add 2g of glycidyl methacrylate dropwise to the mixture of peach gum polysaccharide and persulfate, and react at 60℃ for 1h after the addition is complete to obtain epoxidized peach gum polysaccharide;

[0091] (2) Mix 1g of sulfur powder with 2.5g of sodium hydroxide and stir at 30°C for 3h to prepare sodium polysulfide;

[0092] (3) Add 1g of epoxidized peach gum polysaccharide obtained in step (1) and 0.75g of sodium polysulfide obtained in step (2) to 20g of water to dissolve. After stirring the mixture at 58℃ for 2.5h, move it to room temperature and continue the reaction for 3h. Then, dialyze with deionized water and vacuum dry to obtain antibacterial and antioxidant peach gum polysaccharide.

[0093] Example 5

[0094] A method for preparing antibacterial and antioxidant peach gum polysaccharide, comprising the following steps:

[0095] (1) Dissolve 3g of water-soluble peach gum polysaccharide with a molecular weight of 86000Da and 0.15g of sodium persulfate in 200g of water, stir at 60℃ for 60min under argon atmosphere, and then add 5g of glycidyl methacrylate dropwise to the mixture of peach gum polysaccharide and persulfate. After the addition is complete, react at 50℃ for 3h to obtain epoxidized peach gum polysaccharide.

[0096] (2) Mix 3g of sulfur powder with 7.5g of sodium hydroxide and stir at 30°C for 3 hours to prepare sodium polysulfide;

[0097] (3) Add 3g of epoxidized peach gum polysaccharide obtained in step (1) and 3.6g of sodium polysulfide obtained in step (2) to 200g of water to dissolve. After stirring the mixture at 50℃ for 3h, move it to room temperature and continue the reaction for 3h. Then, dialyze with deionized water and vacuum dry to obtain antibacterial and antioxidant peach gum polysaccharide.

[0098] Example 6

[0099] A method for preparing antibacterial and antioxidant peach gum polysaccharide, comprising the following steps:

[0100] (1) Dissolve 10g of water-soluble peach gum polysaccharide with a molecular weight of 15000Da and 0.45g of potassium persulfate in 500g of water, stir at 62℃ for 30min under nitrogen atmosphere, and then add 18g of glycidyl methacrylate dropwise to the mixture of peach gum polysaccharide and persulfate. After the addition is complete, react at 60℃ for 2h to obtain epoxidized peach gum polysaccharide.

[0101] (2) Mix 10g of sulfur powder with 15g of sodium sulfide and stir at 40°C for 3 hours to prepare sodium polysulfide.

[0102] (3) 10g of epoxidized peach gum polysaccharide obtained in step (1) and 13g of sodium polysulfide obtained in step (2) were added to 400g of water and dissolved. The mixture was stirred at 58℃ for 2h and then moved to room temperature for 3h. After that, it was dialyzed with deionized water and then vacuum dried to obtain antibacterial and antioxidant peach gum polysaccharide.

[0103] Comparative Example 1

[0104] The only difference from Example 1 is that the amount of glycidyl methacrylate added is 10g.

[0105] In Comparative Example 1, the amount of glycidyl methacrylate used resulted in only a portion of the glycidyl methacrylate being successfully grafted onto the gum arabic polysaccharide, while the remainder underwent self-polymerization. This not only resulted in a waste of raw materials but also increased the difficulty and cost of subsequent purification and separation.

[0106] Comparative Example 2

[0107] The only difference from Example 1 is that the amount of sodium hydroxide added is 10g.

[0108] In Comparative Example 2, only a portion of sodium hydroxide participated in the reaction, resulting in a severe excess of sodium hydroxide in the system. This excess sodium hydroxide made the system excessively alkaline, affecting the formation of the final product and inducing partial degradation of the peach gum polysaccharide.

[0109] Comparative Example 3

[0110] Compared with Example 1, the only difference is that after the epoxidized gum polysaccharide and sodium polysulfide are dissolved in water, the reaction is not carried out in a stepped temperature manner, but is directly reacted at 50°C for 6 hours.

[0111] The reaction method in Comparative Example 3 led to excessive cross-linking, ultimately resulting in a product that could only partially dissolve in water.

[0112] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing antibacterial and antioxidant peach gum polysaccharide, characterized in that, Includes the following steps: Under initiator conditions, peach gum polysaccharide and glycidyl methacrylate undergo a graft polymerization reaction in water to prepare epoxidized peach gum polysaccharide; The epoxidized peach gum polysaccharide was dissolved in water with sodium polysulfide and subjected to a gradient temperature reaction. Then, it was dialyzed and dried sequentially to prepare the antibacterial and antioxidant peach gum polysaccharide.

2. The method for preparing antibacterial and antioxidant peach gum polysaccharide according to claim 1, characterized in that, The initiator is persulfate.

3. The method for preparing antibacterial and antioxidant peach gum polysaccharide according to claim 1, characterized in that, The molecular weight of the peach gum polysaccharide is 3000-200000 Da.

4. The method for preparing an antibacterial and antioxidant peach gum polysaccharide according to claim 1, characterized in that, The mass ratio of the peach gum polysaccharide, initiator, water and glycidyl methacrylate is 1:(0.01-0.1):(20-100):(1-3).

5. The method for preparing an antibacterial and antioxidant peach gum polysaccharide according to claim 1, characterized in that, The graft polymerization reaction is carried out at 35–65°C for 1–3 hours.

6. The method for preparing an antibacterial and antioxidant peach gum polysaccharide according to claim 1, characterized in that, The preparation process of the sodium polysulfide is as follows: The sodium polysulfide is prepared by mixing sulfur powder with sodium sulfide or sodium hydroxide and stirring at 30-90°C for 1-3 hours. Wherein, the mass ratio of sulfur powder to sodium sulfide is 1:(1.5-4); or, The mass ratio of sulfur powder to sodium hydroxide is 1:(1.2-3).

7. The method for preparing antibacterial and antioxidant peach gum polysaccharide according to claim 1, characterized in that, The mass ratio of the epoxidized gum polysaccharide, sodium polysulfide, and water is 1:(0.75-1.5):(20-100).

8. The method for preparing antibacterial and antioxidant peach gum polysaccharide according to claim 1, characterized in that, The conditions for the stepped temperature reaction are as follows: first, stir the reaction at 40-70°C for 1-3 hours, and then move it to room temperature to continue the reaction for 3 hours.

9. An antibacterial and antioxidant peach gum polysaccharide, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.

10. The application of the antibacterial and antioxidant peach gum polysaccharide as described in claim 9 in the preparation of food, cosmetics or biomedicine.

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