Morusin rubidium hydrogel and preparation method and use thereof

Abstract

The application discloses a mangiferin-rubidium hydrogel, which is mainly prepared by mixing mangiferin and a rubidium source, has a yellow transparent uniform gel appearance, has a three-dimensional network structure and a porous structure, and has injectability and thermal stability. The application prepares the carrier-free mangiferin-rubidium hydrogel through the reaction of mangiferin and a rubidium salt. The hydrogel has the characteristics of being injectable, self-repairable, easy to shape and highly stable, and the structure of the hydrogel is mainly maintained by hydrogen bonds and intermolecular π-π stacking forces. The hydrogel has a simple preparation process, can inhibit staphylococcus aureus and methicillin-resistant staphylococcus aureus, and has clinical application potential.

Description

Technical Field

[0001] This invention relates to the field of hydrogel technology, specifically to a mangiferin rubidium hydrogel, its preparation method, and its uses. Background Technology

[0002] Hydrogels, as a three-dimensional polymer material with high water content, possess excellent biocompatibility and biomimetic mechanical adaptability. Hydrogels can directly act on specific sites for localized treatment, reducing the risks associated with systemic medication. Their high water content hydrates the stratum corneum, lowers the skin barrier, and promotes transdermal absorption. Self-assembled hydrogels form stable networks without chemical covalent cross-linking through hydrogen bonds and π-π stacking forces. They can slowly degrade in physiological environments, avoiding the cytotoxicity and tissue irritation caused by residual chemical cross-linking agents, making them suitable for short-term medical applications and sustained-release carriers.

[0003] Mangiferin (MGF), also known as mangoside, is a bis(benzopyrone) flavonoid compound and a natural polyphenol found in mango fruit. It possesses significant antibacterial, anti-inflammatory, and antioxidant properties. Traditional topical formulations are complex to prepare, requiring excipients, resulting in slow and irregular release, low transdermal efficiency, and limited efficacy for moderate to severe or deep skin lesions. Furthermore, mangiferin is extremely poorly soluble in water, exhibiting unstable dispersion and easy precipitation in conventional aqueous matrices. This leads to low drug loading, short skin retention time, and often reliance on potentially irritating penetration enhancers, limiting its potential as a clinical therapeutic agent.

[0004] In recent years, carrier-free self-assembled supramolecular hydrogels have attracted widespread attention due to their high drug loading capacity and excellent safety profile. Developing a mangiferin rubidium hydrogel that can be prepared via various simple methods and possesses good mechanical properties and antibacterial activity is of great significance for clinical anti-infective therapy.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a mangiferin rubidium hydrogel, its preparation method and uses, thereby overcoming the shortcomings of mangiferin preparations such as low solubility and complex preparation.

[0007] Another object of the present invention is to provide a use of mangiferin rubidium hydrogel for the preparation of antibacterial drugs or for use as a drug carrier.

[0008] To achieve the above objectives, the present invention provides a mangiferin rubidium hydrogel, which is mainly prepared by mixing mangiferin and a rubidium source. It is a yellow, transparent, and homogeneous gel with a three-dimensional network structure, a porous structure, and good injectability and thermal stability.

[0009] A method for preparing the above-mentioned mangiferin rubidium hydrogel includes mixing mangiferin and a rubidium source and reacting them, followed by heating to obtain the hydrogel.

[0010] Preferably, in the above technical solution, a method for preparing the above-mentioned mangiferin rubidium hydrogel includes the following steps:

[0011] (1) Dissolve mangiferin powder in an ethanol aqueous solution and add rubidium carbonate solution dropwise while stirring to react;

[0012] (2) After the reaction, ethyl acetate was added as an antisolvent to precipitate rubidium mangiferin;

[0013] (3) Mix mangiferin rubidium and water, heat until completely dissolved, to obtain mangiferin rubidium hydrogel.

[0014] Preferably, in the above technical solution, the solid-liquid ratio (mg / mL) of mangiferin powder, ethanol aqueous solution, and 1.5 wt% rubidium carbonate solution in step (1) is 200-800:10-80:5-50; the reaction is carried out at 50-65℃ for 1-5 hours; and / or the amount of acetic acid added as the antisolvent in step (2) is 2.5-3 times the total volume of the reaction solution; and / or the heating temperature in step (3) is 70-85℃, the solid-liquid ratio (mg / mL) of mangiferin rubidium and water is 12.7-67.6:1, and the critical gelling concentration of mangiferin rubidium is 25.34 mg / mL.

[0015] Preferably, in the above technical solution, a method for preparing the above-mentioned mangiferin rubidium hydrogel uses rubidium carbonate as the rubidium source, mixes mangiferin powder and rubidium carbonate aqueous solution, heats to a transparent solution and then cools to room temperature to form a gel.

[0016] Preferably, in the above technical solution, the molar ratio of rubidium carbonate to mangiferin is 0.6:1-0.8:1; more preferably 0.7:1; and the heating temperature is 70-85℃.

[0017] Preferably, in the above technical solution, a method for preparing the above-mentioned mangiferin rubidium hydrogel uses rubidium hydroxide as the rubidium source, mixes mangiferin powder and rubidium hydroxide aqueous solution, heats to a transparent solution and then cools to room temperature to form a gel.

[0018] Preferably, in the above technical solution, the molar ratio of strong rubidium oxide to mangiferin is 0.8:1-1.2:1, more preferably 1.1:1; and the heating temperature is 70-85℃.

[0019] One use of the above-mentioned mangiferin rubidium hydrogel is its application in the preparation of antibacterial drugs.

[0020] Preferably, in the above technical solution, the use of the mangiferin rubidium hydrogel is in the preparation of drugs that inhibit Staphylococcus aureus and methicillin-resistant Staphylococcus aureus.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] (1) The mangiferin rubidium hydrogel of the present invention mainly achieves self-assembly of mangiferin rubidium hydrogel through coordination between phenolic hydroxyl groups and rubidium ions, without the need for additional cross-linking agents, and mangiferin can achieve a high concentration. This self-assembled hydrogel not only has good stability and injectability, but also has antibacterial activity against Staphylococcus aureus and drug-resistant Staphylococcus aureus.

[0023] (2) This invention prepares a carrier-free mangiferin-rubidium hydrogel by reacting mangiferin with rubidium salt. This hydrogel possesses the characteristics of being injectable, self-healing, easily moldable, and highly stable. Its structure is mainly maintained by hydrogen bonds and intermolecular π-π stacking forces. The preparation process of this hydrogel is simple, and it can inhibit Staphylococcus aureus and methicillin-resistant Staphylococcus aureus, showing potential for clinical application. Attached Figure Description

[0024] Figure 1 This is a schematic diagram illustrating the synthesis of mangiferin rubidium salt according to the present invention;

[0025] Figure 2 These are photos of the physical state of the mangiferin rubidium hydrogel (MGF-Rb-H) prepared in Example 2 of this invention and a bottle-inverted experiment.

[0026] Figure 3 These are photos of the physical state of the mangiferin rubidium hydrogel (MGF-Rb2CO3) prepared in Example 3 of this invention and a bottle-inverted experiment.

[0027] Figure 4 These are photos of the physical state of the mangiferin rubidium hydrogel (MGF-RbOH) prepared in Example 4 of this invention and a bottle-inverted experiment.

[0028] Figure 5 This is a diagram illustrating the temperature stability of the mangiferin rubidium hydrogel (MGF-Rb) prepared under the condition of 25.4 mg powder mass in Example 2.

[0029] Figure 6 is a diagram showing the injectability properties of the hydrogels prepared in Examples 2-4 of the present invention; where a is the hydrogel of Example 2, b is the hydrogel of Example 3, and c is the hydrogel of Example 4.

[0030] Figure 7 shows the hydrogel molding images prepared in Examples 2-4 of the present invention; where a is the hydrogel of Example 2, b is the hydrogel of Example 3, and c is the hydrogel of Example 4.

[0031] Figure 8 These are the Fourier transform infrared spectra of the hydrogels in Examples 2, 3, and 4 of this invention;

[0032] Figure 9 This is a scanning electron microscope (SEM) morphology image of the hydrogel in Example 2 of the present invention;

[0033] Figure 10 This is a scanning electron microscope (SEM) morphology image of the hydrogel in Example 3 of the present invention;

[0034] Figure 11 This is a scanning electron microscope (SEM) morphology image of the hydrogel in Example 4 of the present invention;

[0035] Figure 12 These are the results of the comparison of inhibition zones of the hydrogels in Examples 2-4 of this invention against Staphylococcus aureus (S. aureus);

[0036] Figure 13 These are the results of comparing the inhibition zones of the hydrogels in Examples 2-4 of this invention against methicillin-resistant Staphylococcus aureus (MRSA). Detailed Implementation

[0037] The following detailed description, in conjunction with the accompanying drawings, outlines specific embodiments. However, it should be understood that the scope of protection of this invention is not limited to these specific embodiments. Unless otherwise specified, all raw materials and reagents used in the examples are commercially available. Example 1

[0038] Purification of natural mangiferin

[0039] Crude mangiferin (20.00 g) was dissolved in 7 L of 60% ethanol aqueous solution by ultrasonication at 60 °C. After cooling, the solution was stored at room temperature. After 7 days, it was filtered to remove solid impurities. The filtrate was concentrated to obtain approximately 500 ml of yellow suspension. The suspension was filtered and dried to obtain a yellow solid powder (13.79 g, purity >95%).

[0040] Mangiferin yellow solid powder was heated and dissolved in 70% ethanol aqueous solution (2.8 L). The resulting solution was left to stand at room temperature for one week, during which pale yellow needle-like crystals precipitated. After filtration and drying, 5.36 g of purified mangiferin was obtained. Example 2

[0041] The preparation of hydrogels using a synthetic method for mangiferin rubidium includes the following steps:

[0042] (1) Synthesis of rubidium mangiferin: 422.3 mg of purified mangiferin was added to a 500 ml round-bottom flask, along with 21 ml of anhydrous ethanol and 3 ml of water. The mixture was stirred in a 60 °C water bath for 30 min, and then 18.75 ml of 1.5 wt% Rb₂CO₃ solution was added dropwise. After reacting for 2 h, 70 ml of ethyl acetate was added, and a yellow solid precipitated. After filtration and drying, rubidium mangiferin powder (MGF-Rb) was obtained with a yield of 90.5%. The synthetic route is as follows: Figure 1 As shown.

[0043] (2) Preparation of gel: Weigh mangiferin rubidium powder (MGF-Rb) and add it to 1.0 ml of pure water. Heat at 80°C until completely dissolved and then cool to room temperature to form a stable hydrogel, which is denoted as MGF-Rb-H hydrogel.

[0044] The powder masses weighed above were 12.7 mg, 19.1 mg, 25.4 mg, 38.1 mg, and 76.1 mg, respectively. That is, after exploring within the range of 12.7-76.1 mg, the critical gelling concentration was found to be 25.4 mg / ml (i.e., 0.05 mmol). Figure 2 As shown. Figure 2 The hydrogels from left to right are experimental images of MGF-Rb-H hydrogels prepared with added powder at masses of 12.7 mg, 19.1 mg, 25.4 mg, 38.1 mg, and 76.1 mg. Example 3

[0045] Preparation of mangiferin and rubidium carbonate hydrogels

[0046] 21.1 mg of purified mangiferin was added to 1 ml of an aqueous solution containing Rb₂CO₃. The mixture was heated to 80°C until the reaction was complete, and then cooled to room temperature to form a transparent gel, which was designated as MGF-Rb₂CO₃ hydrogel.

[0047] The molar ratio of rubidium carbonate to mangiferin was set to 0.6:1, 0.7:1, and 0.8:1; that is, the molar ratio of rubidium carbonate to mangiferin was set to a range of 0.6:1-0.8:1. This was verified using the inverted vial method, with 0.7:1 being the preferred ratio. Figure 3 As shown. Figure 3 From left to right, the hydrogel settings have a molar ratio of rubidium carbonate to mangiferin of 0.6:1, 0.7:1, and 0.8:1. Example 4

[0048] Preparation of mangiferin and rubidium hydroxide hydrogel

[0049] 21.1 mg of mangiferin powder was added to 1 ml of an aqueous solution containing RbOH. The mixture was heated to 80°C until the reaction was complete, forming a transparent gel, which was designated as MGF-RbOH hydrogel.

[0050] The molar ratio of rubidium hydroxide to mangiferin was set to 0.8:1, 0.9:1, 1:1, 1.1:1, and 1.2:1. That is, the molar ratio of rubidium hydroxide to mangiferin ranged from 0.8:1 to 1.2:1. This was verified using the inverted vial method, and 1.1:1 was preferred. Figure 4 As shown. Figure 4 From left to right, the hydrogel settings have molar ratios of rubidium hydroxide and mangiferin of 0.8:1, 0.9:1, 1:1, 1.1:1, and 1.2:1. Example 5

[0051] Temperature stability study

[0052] The hydrogels prepared under the conditions of 25.4 mg powder in Example 2, 0.7:1 molar ratio of rubidium carbonate to mangiferin in Example 3, and 1.1:1 molar ratio of rubidium hydroxide to mangiferin in Example 4 were placed in three 5 ml glass bottles, sealed, and heated to observe whether the flow of the gels was affected by gravity. When the temperature was increased by 50–80 °C, all three hydrogels maintained stability throughout the heating and cooling process. This was verified by the bottle inversion method; no flow occurred when the bottle was inverted. When the hydrogel prepared under the condition of 25.4 mg powder in Example 2 was further heated to 90 °C, the gel exhibited flow characteristics under heated conditions. After cooling, the intermolecular non-covalent forces were reconstructed, the gel network structure was restored, and the system no longer flowed, as shown in the figure. Figure 5 As shown, the hydrogel exhibits strong internal forces that allow it to maintain its inherent morphology and skeletal integrity under both room temperature and moderately heated conditions, thus providing protection for complex drug application environments. Example 6

[0053] Injectability study of hydrogels

[0054] The hydrogels prepared under the following conditions were loaded into sterile syringes: the hydrogel prepared under the following conditions: 25.4 mg powder mass in Example 2; the hydrogel prepared under the following conditions: 0.7:1 molar ratio of rubidium carbonate to mangiferin in Example 3; and the hydrogel prepared under the following conditions: 1.1:1 molar ratio of rubidium hydroxide to mangiferin in Example 4. The hydrogels were injected into phosphate buffer solution (pH=7.4) by manual injection using a medical syringe to simulate the clinical drug administration injection process, and the process was recorded by taking pictures.

[0055] like Figure 6From left to right, Examples 2, 3, and 4 illustrate the simulated clinical drug delivery injection using hydrogels. The results show that all three hydrogels exhibit excellent injectability; the syringe can smoothly draw the gel into the syringe barrel. During the simulation, they demonstrated excellent shear-thinning properties, allowing for continuous and smooth delivery through the injection needle for precise administration. In other words, the structure of the three hydrogels was not disrupted by shear forces, possessing suitable viscosity and flowability, enabling precise quantitative control of the drug delivery volume, and demonstrating potential for injectable applications. Example 7

[0056] Formability study of hydrogels

[0057] The hydrogels prepared in Example 2 (25.4 mg powder), Example 3 (rubidium carbonate and mangiferin molar ratio of 0.7:1), and Example 4 (rubidium hydroxide and mangiferin molar ratio of 1.1:1) were injected into a glass substrate using a syringe to create different shapes. The experimental results are shown in Figure 7, which, from top to bottom, represents the formed states of the hydrogels prepared in Examples 2, 3, and 4. After standing for 30 minutes, the gel morphology remained intact, demonstrating the excellent forming properties of this series of hydrogels. Example 8

[0058] Fourier transform infrared spectra of hydrogels

[0059] The presence of specific chemical bonds in the hydrogel was confirmed using Fourier transform infrared spectroscopy. First, background acquisition was performed on a blank potassium bromide sample. Then, the lyophilized hydrogel powder and potassium bromide powder were compressed together into a pellet and placed on a rack in the sample chamber for 4000–400 cm⁻¹ spectroscopy. -1 The spectral scans were performed. The samples were hydrogels prepared with 25.4 mg of powder as described in Example 2, hydrogels prepared with a molar ratio of 0.7:1 for rubidium carbonate and mangiferin as described in Example 3, and hydrogels prepared with a molar ratio of 1.1:1 for rubidium hydroxide and mangiferin as described in Example 4.

[0060] In the infrared spectrum of mangiferin, at 3450 cm⁻¹ -1 It is a characteristic peak of the stretching vibration of the hydroxyl group (-OH). For example... Figure 8 As shown, for the three hydrogels, this characteristic peak red-shifted to 3350, 3370, and 3390 cm⁻¹, respectively. -1 Furthermore, the peak shape broadened and deepened significantly, and the stretching vibration of the hydroxyl group (-OH) showed a redshift, revealing the formation of hydrogen bonds. The formation of hydrogen bonds weakens the bond energy of the OH covalent bond, leading to a decrease in its stretching vibration frequency. The greater the redshift, the stronger the hydrogen bond or the shorter the bond length. That is, hydrogen bonds are formed during the self-assembly process, making the physical cross-linking denser and stabilizing the three-dimensional structure of the hydrogel. Example 9

[0061] Scanning electron microscopy morphology of the hydrogel

[0062] Hydrogels prepared under the following conditions were collected: 25.34 mg of powder in Example 2; rubidium carbonate and mangiferin in Example 3 (molar ratio of 0.7:1); and rubidium hydroxide and mangiferin in Example 4 (molar ratio of 1.1:1). These three hydrogels were freeze-dried into powder samples. After gold sputtering, the samples were subjected to scanning electron microscopy (SEM) to obtain hydrogel morphology images, and the surface and cross-sectional morphology were observed. Figure 9-11 As shown, all three hydrogels have a porous structure. Example 10

[0063] Comparison of inhibition zones of hydrogels against pathogenic bacteria

[0064] The hydrogels prepared under the following conditions were selected for antibacterial experiments: the hydrogel prepared under the following conditions: Example 2 with a powder mass of 25.4 mg, Example 3 with a molar ratio of rubidium carbonate to mangiferin of 0.7:1, and Example 4 with a molar ratio of rubidium hydroxide to mangiferin of 1.1:1.

[0065] Preparation of MH solid medium (MHA): Take 38.0 g of dried MHA powder, add 1 L of pure water, stir and mix well, autoclave at 121℃ for 15 min, pour into petri dishes after slightly cooling, and obtain MH solid medium after cooling and solidification, for later use.

[0066] Preparation of MH liquid culture medium (MHB): Take 24.0 g of dried MHB powder, add 1 L of pure water, stir and mix well, autoclave at 121℃ for 15 min, and set aside.

[0067] Bacterial activation: Take out the strain stored in the refrigerator (-80°C), and after it returns to room temperature, dilute it. Take 100 μL of Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA) strains and spread them on MH agar medium. Incubate in a constant temperature and humidity incubator for 24 h to obtain the desired colonies.

[0068] Single colonies of *S. aureus* and *MRSA* were transferred from MH solid medium to MH liquid medium and incubated on a shaker (37°C, 150 rpm) for 12 h. Once the bacteria reached the stationary phase, the bacterial culture was diluted to 1 × 10⁻⁶. 5After obtaining CFU / mL, 100 μL of the sample was spread onto MH solid medium. Sterilized Oxford cups were used to create wells in agar plates, and 100 μL of the test sample was injected into each well. Vancomycin (10 μg / mL) was used as a positive control. The MH solid medium containing the test sample was incubated in a constant temperature and humidity incubator for 18-24 h. The size of the inhibition zone was observed, the diameter of the inhibition zone was measured, and photographed. Each bacterial treatment was performed in triplicate. Figure 12-13 As shown, the rubidium salt and mangiferin suspensions showed no significant inhibitory effect. The inhibition zone diameters of the hydrogels prepared in Examples 2, 3, and 4 were approximately the same as those of vancomycin, with an inhibition zone diameter of about 1.8 cm. These results indicate that the mangiferin-rubidium hydrogel has a significant antibacterial effect.

[0069] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A mangiferin rubidium hydrogel, characterized in that, It is mainly prepared by mixing mangiferin and rubidium source. It appears as a yellow, transparent, and homogeneous gel with a three-dimensional network structure, porous structure, injectability, and thermal stability.

2. A method for preparing the mangiferin rubidium hydrogel as described in claim 1, characterized in that, This involves mixing mangiferin and a rubidium source, reacting them, and then heating the mixture to obtain a hydrogel.

3. The method for preparing mangiferin rubidium hydrogel according to claim 2, characterized in that, Includes the following steps: (1) Dissolve mangiferin powder in an ethanol aqueous solution and add rubidium carbonate solution dropwise while stirring to react; (2) After the reaction, ethyl acetate was added as an antisolvent to precipitate rubidium mangiferin; (3) Mix mangiferin rubidium and water, heat until completely dissolved, to obtain mangiferin rubidium hydrogel.

4. The method for preparing mangiferin rubidium hydrogel according to claim 3, characterized in that, Step (1) The solid-liquid ratio of mangiferin powder, ethanol solution, and 1.5 wt% rubidium carbonate solution (mg / mL) is 200-800:10-80:5-50; react at 50-65℃ for 1-5 hours. And / or in step (2), the amount of acetic acid added as an antisolvent is 2.5-3 times the total volume of the reaction solution; And / or the heating temperature in step (3) is 70-85℃, the solid-liquid ratio of mangiferin rubidium and water is 12.7-67.6:1 mg / ml, and the critical gelling concentration of mangiferin rubidium is 25.34 mg / ml.

5. The method for preparing mangiferin rubidium hydrogel according to claim 2, characterized in that, Using rubidium carbonate as the rubidium source, mangiferin powder and rubidium carbonate aqueous solution were mixed, heated to a transparent solution, and then cooled to room temperature to form a gel.

6. The method for preparing mangiferin rubidium hydrogel according to claim 5, characterized in that, The molar ratio of rubidium carbonate to mangiferin is 0.6:1-0.8:1; preferably 0.7:1; the heating temperature is 70-85℃.

7. The method for preparing mangiferin rubidium hydrogel according to claim 2, characterized in that, Using rubidium hydroxide as the rubidium source, mangiferin powder and rubidium hydroxide aqueous solution were mixed, heated to a transparent solution, and then cooled to room temperature to form a gel.

8. The method for preparing mangiferin rubidium hydrogel according to claim 7, characterized in that, The molar ratio of strong rubidium oxide to mangiferin is 0.8:1-1.2:1, preferably 1.1:1; The heating temperature is 70-85℃.

9. The use of the mangiferin rubidium hydrogel as described in any one of claims 1-9, characterized in that, Application of mangiferin rubidium hydrogel in the preparation of antibacterial drugs.

10. The use according to claim 9, characterized in that, The application of the mangiferin rubidium hydrogel in the preparation of drugs that inhibit Staphylococcus aureus and methicillin-resistant Staphylococcus aureus.

Images