A paeonol-loaded solvent-free gel, its gel matrix, preparation method and use

Abstract

The present application provides a kind of loading paeonol solvent-free gel and its gel matrix, preparation method and purposes, the gel matrix includes lipoic acid, prolamine and polyacid, the method for preparing solvent-free gel using the gel matrix loading paeonol is as follows: (1) paeonol is heated and melted by mixing with the gel matrix composition;(2) the product obtained in (1) is swelled with alcohol-water mixture, heated and foamed after removing the solution, and cooled to obtain the gel patch.The raw materials of the present application are green and non-toxic, the preparation process is simple, the cost is low, suitable for loading a large amount of paeonol, and can effectively realize the transdermal sustained release of paeonol.The animal clinical experiment proves that the obtained gel patch has application prospect in the treatment of skin eczema.

Description

Technical Field

[0001] This invention belongs to the field of biomedical polymers, and relates to a solvent-free gel loaded with paeonol, a gel matrix and method for preparing the solvent-free gel, and the application of the solvent-free gel and the gel matrix. Background Technology

[0002] Paeonol, also known as peony bark extract, is a bioactive substance extracted from the traditional Chinese medicines peony root bark (dried root bark of peony) or cynanchum paniculatum (dried root and rhizome of cynanchum paniculatum). It possesses anti-inflammatory, anti-diabetic, cardiovascular-improving, anti-tumor, and neuroprotective effects, and can be used to treat various skin diseases [Food Chem. 2021, 365, 130384]. However, the clinical application of paeonol is relatively limited due to its poor water solubility and rapid metabolism, resulting in low bioavailability. To address this, it can be loaded onto a polymer matrix to achieve sustained-release and long-acting administration, thereby improving bioavailability. However, in practical applications, the loading capacity is often limited.

[0003] To improve the loading capacity of paeonol, modern research has introduced hydrogels for solubilization [Life Sci. 2020, 250, 117544]. However, hydrogels using water as a continuous medium cannot overcome the limitation of water evaporation in practical applications. This process often leads to gel network collapse and colloid aging, accompanied by decreased mechanical properties, reduced tissue adhesion, and drug spillage [Angew. Chem., Int. Ed. 2022, 134(4), e202115021]. In addition, hydrogels often face limitations such as low loading capacity of lipid-soluble drugs and poor stability, limiting their application in the field of drug sustained release [Appl. Mater. Today 2018, 12, 294-308]. Although researchers have attempted to overcome the limitations of hydrogel dehydration and low loading capacity of lipid-soluble drugs by using methods such as solvent replacement and oil-water interface coating, these improvements often involve lengthy molecular modification steps or time-consuming synthetic routes [Adv. Func. Mater. 2018, 28(49), 1800793]. Therefore, there is an urgent need for new gel systems to overcome the bottlenecks of hydrogel dehydration deformation and narrow drug loading range, in order to meet complex and varied application conditions and pathological needs. Summary of the Invention

[0004] The problem the invention aims to solve

[0005] The biggest limitation of paeonol as a clinical drug lies in its poor water solubility and rapid metabolism, resulting in low bioavailability. Modern research has attempted to achieve sustained-release and long-acting drug delivery by loading it onto polymer matrices, but when using hydrogel systems, problems arise such as easy dehydration and deformation of the colloid, low loading capacity of lipid-soluble drugs, poor stability, and complex solvent replacement procedures.

[0006] Solution for solving the problem

[0007] Sulfur is abundant and inexpensive in nature. Disulfide bonds (SS) can undergo dynamic and reversible chemical cross-linking under high temperature, ultraviolet light, and anionic catalysis, and the resulting polysulfides are miscible with a variety of substances or materials in the absence of solvents. Furthermore, most biological proteins possess thiol groups and disulfide bonds, which can participate in the dynamic cross-linking of SS, leading to novel gel systems. This is of great significance for improving tissue adhesion and obtaining green pharmaceutical products. Therefore, gel networks based on organic SS not only hold promise for increasing the loading capacity of lipid-soluble or poorly water-soluble drugs but also have the potential to be used as novel topical formulations for the treatment of various skin diseases.

[0008] Preliminary exploratory experiments have demonstrated that lipoic acid can co-dissolve with drugs such as paeonol, cinnamic acid, and styrax at 70°C, forming a homogeneous solution. Furthermore, lipoic acid and proteases can participate in dynamic cross-linking of SS (sulfuric acid-thiol-sulfuric acid) to obtain novel gel systems. Therefore, gel networks based on covalent cross-linking networks with disulfide bonds (formed through the sulfur radical-thiol reaction between lipoic acid and proteases) hold promise for solving the problems faced by existing technologies.

[0009] [1] The present invention first provides a solvent-free gel matrix composition comprising lipoic acid, prolyl protein and polyacids;

[0010] Preferably, the gel matrix comprises, by weight, 2-5 parts of lipoic acid, 0.06-0.33 parts of prolysin and 0.06-0.16 parts of polyacid.

[0011] [2] The solvent-free gel matrix composition according to [1], wherein,

[0012] The prolysin is zein, rye prolysin, or barley prolysin; and / or

[0013] The polyacids mentioned are citric acid, tartaric acid, or malic acid.

[0014] [3] Application of the solvent-free gel matrix composition according to [1] or [2] in the preparation of solvent-free gels;

[0015] Preferably, the solvent-free gel is a drug-loaded solvent-free gel;

[0016] More preferably, the solvent-free gel is a solvent-free gel loaded with a lipid-soluble drug;

[0017] More preferably, the solvent-free gel is a solvent-free gel loaded with paeonol.

[0018] [4] A solvent-free gel loaded with paeonol, which is made of paeonol and a solvent-free gel matrix composition according to [1] or [2];

[0019] Preferably, the weight ratio of paeonol to thioctic acid in the solvent-free gel matrix composition is 1:2-5.

[0020] [5] The method for preparing the solvent-free gel loaded with paeonol according to [4] includes the following steps:

[0021] (1) Grind paeonol, thioctic acid, prolactin and polyacids to 150-250 mesh, put them into a mold and heat to melt;

[0022] (2) The product obtained in (1) is swollen with an alcohol-water mixture, the solution is removed, the product is heated to remove bubbles, and then cooled to obtain the finished product.

[0023] [6] According to the preparation method described in [5], wherein,

[0024] The heating and melting temperature is 70–100°C; and / or

[0025] The heating and melting time is 0.5 to 1 hour.

[0026] [7] The preparation method according to [5] or [6], wherein,

[0027] The alcohol-water mixture contains 50-75% v / v ethanol and 50-25% v / v water; and / or

[0028] The mass ratio of the amount of paeonol added to the alcohol-water mixture is 1:3 to 1:5.

[0029] [8] The preparation method according to any one of [5]-[7], wherein,

[0030] The swelling time is 10 to 30 minutes.

[0031] [9] The preparation method according to any one of [5]-[8], wherein,

[0032] The heating and degassing time is 0.5 to 2 hours.

[0033]

[10] The use of the solvent-free gel loaded with paeonol according to [4] or the solvent-free gel loaded with paeonol prepared by any one of the preparation methods according to [5]-[9] in the preparation of a medicament for treating skin eczema.

[0034] The effects of the invention

[0035] (1) The present invention provides a solvent-free gel loaded with paeonol, which has the advantages of simple preparation process, green and natural raw materials and low cost.

[0036] (2) The method for preparing the solvent-free gel loaded with paeonol in this invention employs grinding and heating to simultaneously complete the polymerization reaction and gelation. Furthermore, thioctic acid, after melting, is miscible with paeonol, thereby increasing the paeonol loading.

[0037] (3) The solvent-free gel loaded with paeonol of the present invention has stable size, morphology and properties, and does not have the problems of collapse and aging caused by solvent evaporation. It also has properties such as stretchability, antibacterial, tissue adhesion and self-repair.

[0038] (4) The solvent-free gel loaded with paeonol of the present invention can release paeonol through transdermal administration and can be used to treat skin eczema. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the preparation process and appearance of the solvent-free gel in Example 1 of the present invention. The leftmost side shows the state after grinding, the middle side shows the state after initial heating and melting, and the rightmost side shows the state after the degassing step.

[0040] Figure 2 The image shows the infrared spectrum of the solvent-free gel in Example 1 of this invention.

[0041] Figure 3 The mass changes of the solvent-free gels in Examples 1-6 of this invention during immersion in 75% alcohol solution (a), water (b), and ethanol solution (c) are shown.

[0042] Figure 4 The stretching curves are those of the solvent-free gels in Examples 1 to 6 of this invention.

[0043] Figure 5 The results of the inhibition zone experiment of the solvent-free gel against methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli) in Example 4 of this invention are shown.

[0044] Figure 6 The adhesion curves (a) and statistical results (b) of the solvent-free gel to pigskin in Examples 1-6 of this invention are shown.

[0045] Figure 7The images shown are (a) and (b) of the self-healing rheological curve of the solvent-free gel in Example 4 of this invention.

[0046] Figure 8 The flowchart (a) and the state of the back skin of each group (b) of the solvent-free gel treatment of the Kunming mouse skin eczema model in Example 1 of the present invention are shown. From left to right, they are blank control group, model group, dexamethasone acetate group and solvent-free gel group.

[0047] Figure 9 This is a schematic diagram of the preparation process of the solvent-free gel loaded with paeonol according to the present invention. Detailed Implementation

[0048] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below. The term "exemplary" as used herein means "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior to or better than other embodiments.

[0049] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In other instances, methods, means, apparatus, and steps well known to those skilled in the art have not been described in detail in order to highlight the spirit of the present invention.

[0050] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0051] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0052] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., mean that a specific element (e.g., based on, feature, structure, property, and / or characteristic) related to that embodiment is included in at least one of the embodiments described herein, and may or may not be present in other embodiments. Furthermore, it should be understood that the elements may be combined in any suitable manner in various embodiments.

[0053] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0054] In this instruction manual, when "room temperature" or "room temperature" is used, the temperature can be between 10-40℃.

[0055] <First Aspect>

[0056] In a first aspect of the invention, a solvent-free gel matrix composition is provided, comprising lipoic acid, prolyl protein, and polyacid;

[0057] By weight, the gel matrix contains 2-5 parts of lipoic acid, 0.06-0.33 parts of prolysin and 0.06-0.16 parts of polyacid.

[0058] In some specific embodiments, the solvent-free gel matrix composition comprises thioctic acid, prolyl protein, and polyacids.

[0059] Alpha-lipoic acid

[0060] Lipoic acid, also known as DL-lipoic acid, has the molecular formula C8H. 14 O2S2 has the following structural formula:

[0061]

[0062] Alpha-lipoic acid is an organosulfur compound that acts as a coenzyme in acyl transfer during metabolism, eliminating free radicals that accelerate aging and cause disease. After being absorbed through the intestines, alpha-lipoic acid enters cells and exhibits both lipid and water solubility.

[0063] In this invention, lipoic acid is used as a polymerizing monomer. When heated, it undergoes a ring-opening polymerization reaction to generate sulfur free radicals, which can cross-link with the following alcohol-soluble proteins through disulfide bonds to form a covalent gel network.

[0064] In addition, thioctic acid reaches its melting point at 70°C and forms a solvent, which can effectively dissolve lipid-soluble drugs such as paeonol, cinnamic acid, and styrax to form a homogeneous solution, thereby achieving the effect of drug loading.

[0065] Glycoprotein

[0066] Gliadin, a component of the protein storage system in plant seeds, is found in wheat and corn. Gliadin possesses strong water, heat, and fat resistance, and is widely used in the food, pharmaceutical, textile, and paper industries. Gliadin can also be used enzymatically to produce bioactive peptides, which can be used in pharmaceuticals.

[0067] In this invention, prolamin is used as a chemical cross-linking agent. The thiol groups contained in prolamin generate sulfur free radicals at high temperatures, which then cross-link with the aforementioned lipoic acid through disulfide bonds to form a covalent gel network. In some specific embodiments, the prolamin can be zein, rye prolamin, or barley prolamin, etc.

[0068] polyacids

[0069] In this invention, the polybasic acid is used as a supramolecular crosslinking agent. Due to its strong acidity, it can undergo hydrogen bonding with the carboxyl groups of the aforementioned lipoic acid, thereby improving the gel's shapeability and mechanical strength. In some specific embodiments, the polybasic acid can be citric acid, tartaric acid, or malic acid.

[0070] Citric acid, also known as citric acid, has the molecular formula C6H8O7 and its structural formula is as follows:

[0071]

[0072] Citric acid is an important organic acid. It is a colorless crystal, odorless, with a strong sour taste, and is easily soluble in water. It is a natural preservative and food additive.

[0073] Tartaric acid, also known as 2,3-dihydroxysuccinic acid, is a carboxylic acid with the chemical formula C4H6O6 and its structural formula is as follows:

[0074]

[0075] Tartaric acid is found in many plants, such as grapes and tamarind. It is also one of the main organic acids in wine. As an antioxidant added to food, it can impart a sour taste. Tartaric acid's greatest use is as a beverage additive, and it is also a raw material in the pharmaceutical industry.

[0076] Malic acid, also known as 2-hydroxybutyric acid, has the chemical formula C4H6O5 and its structural formula is:

[0077]

[0078] Malic acid is found in almost all fruits, with the highest concentration in pome fruits. It is a colorless needle-like crystal or white crystalline powder, odorless, with a pungent and refreshing sour taste. It is an important intermediate product in the human body's internal circulation and is easily absorbed. Therefore, it is widely used as a high-performance food additive and functional food in the food, cosmetics, medical, and health product industries.

[0079] <Second aspect>

[0080] In a second aspect of the invention, the use of the solvent-free gel matrix composition described in the first aspect in the preparation of solvent-free gels is provided.

[0081] In some specific implementations, the solvent-free gel is a drug-loaded solvent-free gel.

[0082] In some more specific embodiments, the solvent-free gel is a solvent-free gel loaded with a lipid-soluble drug.

[0083] In some more specific embodiments, the solvent-free gel is a solvent-free gel loaded with paeonol.

[0084] <Third aspect>

[0085] In a third aspect of the invention, a solvent-free gel loaded with paeonol is provided, which is made of paeonol and the solvent-free gel matrix composition described in the first aspect.

[0086] In some specific embodiments, the weight ratio of paeonol to thioctic acid in the solvent-free gel matrix composition is 1:2-5.

[0087] Paeonol

[0088] The chemical formula of paeonol is C9H. 10 O3 is an active ingredient extracted from the dried root bark of Paeonia suffruticosa, a plant in the Ranunculaceae family. Its structural formula is:

[0089]

[0090] Paeonol has sedative, hypnotic, antibacterial, anti-inflammatory, antioxidant, and blood pressure-lowering effects. In daily chemical applications, it can inhibit intracellular O2. 2- The generation of free radicals can whiten the skin, reduce and fade deposited pigments, and eliminate bruising and blemishes. It also has anti-inflammatory, anti-swelling, analgesic, anti-allergic, and antiviral effects. It has good therapeutic and health-promoting effects on pigmentation, muscle pain, itchy skin, psoriasis, shingles, and eczema. Furthermore, it has good effects in toothpaste, mouthwash, tooth powder, and toothache remedies.

[0091] <Fourth Aspect>

[0092] In a fourth aspect of the invention, a method for preparing the solvent-free gel loaded with paeonol as described in the third aspect is provided, comprising the following steps:

[0093] (1) Grind paeonol, thioctic acid, prolactin and polyacids to 150-250 mesh, put them into a mold and heat to melt;

[0094] (2) The product obtained in (1) is swollen with an alcohol-water mixture, the solution is removed, the product is heated to remove bubbles, and then cooled to obtain the finished product.

[0095] In some specific implementations, the heating and melting temperature is 70 to 100°C, such as 70°C, 80°C, 85°C, 90°C, 100°C, etc.

[0096] In some specific implementations, the heating and melting time is 0.5 to 1 hour, for example, 0.5 hours, 0.6 hours, 0.7 hours, 0.8 hours, 0.9 hours, 1 hour, etc.

[0097] In some specific embodiments, the alcohol-water mixture contains 50%-75% v / v ethanol, such as 50% v / v, 55% v / v, 60% v / v, 65% v / v, 70% v / v, 75% v / v, etc.

[0098] In some specific implementations, the mass ratio of the amount of paeonol added to the alcohol-water mixture is 1:3 to 1:5, for example, 1:3, 1:4, 1:5, etc.

[0099] In some specific implementations, the swelling time is 10 to 30 minutes, such as 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, etc.

[0100] In some specific implementations, the heating and degassing time is 0.5 to 2 hours, for example, 0.5 hours, 1 hour, 1.5 hours, 1.8 hours, or 2 hours.

[0101] In some specific implementations, the heating and dehydration time is 1 to 2 hours.

[0102] <Fifth Aspect>

[0103] The present invention also provides the application of the solvent-free gel loaded with paeonol described in the present invention in the treatment of skin eczema.

[0104] In some specific embodiments, the paeonol loading of the gel accounts for 30-40% of the total gel mass.

[0105] The technical solution of the present invention will be described in detail below with reference to embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used that do not specify the manufacturer are all commercially available conventional products.

[0106] Preparation of drug-loaded solvent-free gels

[0107] Example 1

[0108] One part (1g each) of paeonol, three parts of lipoic acid, 0.06 parts of zein, and 0.06 parts of citric acid were ground and mixed evenly, placed in a polypropylene mold, and heated at 90°C for 0.5 hours to melt. Then, three parts of 75% alcohol solution were added to soak for 10 minutes to swell. After removing the solution, the mixture was heated again at 90°C for 1 hour to degas. After cooling to room temperature, the finished product (denoted as TGG-A) was obtained.

[0109] Example 2

[0110] One part (1g each) of paeonol, two parts of lipoic acid, 0.33 parts of zein, and 0.16 parts of tartaric acid were ground and mixed evenly, placed in a polypropylene mold, and heated at 100°C for 1 hour to melt. Then, four parts of 55% alcohol solution were added to soak for 30 minutes to swell. After removing the solution, the mixture was heated again at 100°C for 1 hour to degas. After cooling to room temperature, the finished product (denoted as TGG-B) was obtained.

[0111] Example 3

[0112] One part (1g per part) of paeonol, five parts of lipoic acid, 0.20 parts of rye gliadin, and 0.10 parts of malic acid were ground and mixed evenly, placed in a polypropylene mold, and heated at 70°C for 0.8h to melt. Then, three parts of 60% alcohol solution were added to soak for 20min to swell. After removing the solution, the mixture was heated again at 75°C for 2h to degas. After cooling to room temperature, the finished product (denoted as TGG-C) was obtained.

[0113] Example 4

[0114] One part (1g per part) of paeonol, 2.5 parts of lipoic acid, 0.30 parts of barley gliadin, and 0.08 parts of citric acid were ground and mixed evenly, placed in a polypropylene mold, and heated at 80°C for 0.6 hours to melt. Then, 5 parts of 70% alcohol solution were added to soak for 15 minutes to swell. After removing the solution, the mixture was heated again at 80°C for 1 hour to degas. After cooling to room temperature, the finished product (denoted as TGG-D) was obtained.

[0115] Example 5

[0116] One part (1g each) of paeonol, 4.5 parts of lipoic acid, 0.10 parts of zein, and 0.08 parts of citric acid were ground and mixed evenly, placed in a polypropylene mold, and heated at 100°C for 1 hour to melt. Then, three parts of 75% alcohol solution were added to soak for 10 minutes to swell. After removing the solution, the mixture was heated again at 100°C for 1.5 hours to degas. After cooling to room temperature, the finished product (denoted as TGG-E) was obtained.

[0117] Example 6

[0118] One part (1g per part) of paeonol, 3.5 parts of lipoic acid, 0.08 parts of zein, and 0.15 parts of tartaric acid were ground and mixed evenly, placed in a polypropylene mold, and heated at 85°C for 0.5h to melt. Then, 5 parts of 55% alcohol solution were added to soak for 30min to swell. After removing the solution, the mixture was heated again at 85°C for 1.8h to degas. After cooling to room temperature, the finished product (denoted as TGG-F) was obtained.

[0119] Performance testing experiment

[0120] (1) Infrared testing

[0121] The dried KBr was ground together with paeonol, citric acid, zein, lipoic acid, or the lyophilized gel powder from Example 1, placed in a metal mold, and pressure was applied to form a KBr pellet, which was then measured using a Frontier infrared spectrometer. Figure 2 As shown, the obtained gels were measured at 2925, 2858, and 1696 cm⁻¹. -1 Characteristic peaks similar to those of lipoic acid appear, corresponding to the aliphatic CH stretching vibration peak and carboxyl peak of lipoic acid, respectively. These peaks are located in the range of 3100–3700 cm⁻¹. -1 The strong, broad peak corresponds to the OH stretching vibration peak, originating from the hydroxyl groups of zein and paeonol. The milled-thermally induced gel exhibits characteristic peaks for paeonol acyl (-COCH3) and Ar-O-CH3 groups, located at 1628, 1252, and 1066 cm⁻¹, respectively. -1 This proves that the gel is loaded with paeonol.

[0122] (2) Swelling test

[0123] The gels obtained in Examples 1-6 were respectively immersed in 75% alcohol, water, and ethanol solutions. At certain intervals (1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 24h, 48h, 72h, 96h, 120h), the gels were removed, drained, and weighed. The weight ratio W before and after immersion was calculated. t / W0, where W t W1 represents the weight of the gel after soaking, and W2 represents the weight of the gel before soaking. The results are as follows: Figure 3 As shown.

[0124] The results showed that the gel did not dissolve in any of the different solvents, indicating that chemical cross-linking occurred during the preparation process, forming a stable polymer network structure. The gel swelled by 20% in 75% alcohol and 10% in ethanol, but did not swell at all in water. These results demonstrate that this type of gel has good solvent resistance and a low swelling rate.

[0125] (3) Tensile test

[0126] Solvent-free gel patches (17 mm wide, 34 mm long, and 3 mm thick) were prepared in polypropylene molds according to the methods in Examples 1-6. The mechanical properties of the gels were measured using a tensile testing machine (Al-3000, GOTECH, Dongguan, China) equipped with a 500 N force sensor, with the following parameters set: tensile speed of 100 mm / min and initial gauge length of 15 mm.

[0127] like Figure 4As shown, the average tensile strength of the gel ranges from 21 kPa to 29 kPa, and the elongation at break can reach 3000%-6000%. Increasing the proportion of paeonol leads to a decrease in tensile strength. Conversely, increasing the amount of zein and polybasic acid crosslinking agents improves tensile strength. Increased polybasic acid content results in a significant increase in the maximum elongation at break.

[0128] (4) Antibacterial zone test

[0129] Luria-Bertany (LB) medium was prepared by adding 10 g tryptone, 5 g yeast extract, 10 g sodium chloride, and 10 g agar to 950 mL of deionized water. The pH of the mixture was adjusted to 7.0 by titrating with sodium hydroxide solution (5 M). The volume of LB medium was then increased to 1 L by adding deionized water. The medium was placed in an autoclave (121 °C, 0.1 MPa) for 20 min. Afterward, the medium was placed on a clean bench and cooled to 40 °C. After gentle shaking, the LB medium was poured into bacterial culture dishes and allowed to stand until solidification. Methicillin-resistant Staphylococcus aureus (MRSA) (ATCC 33592) and Escherichia coli (E. coli) (ATCC 25922) were cultured in LB medium at 37 °C for 24 h. Before the inhibition zone test, the bacterial concentration was adjusted to 5 × 10⁻⁶. 8 CFU / mL.

[0130] Polyvinyl alcohol (PVA) was dissolved in pure water at 90°C for 1 hour, followed by a 6-hour freeze-thaw cycle to obtain a PVA hydrogel (20 wt%). Prior to testing, the gels (PVA hydrogel, solvent-free gel without paeonol, and solvent-free gel containing paeonol prepared according to Example 4) were treated with 75% ethanol. After sterilization and dissolution with distilled water, LB medium was poured into petri dishes and spread on plates. Subsequently, bacterial solutions were introduced into the medium and incubated until solidification. A gel plate (12 mm in diameter, 3 mm thick) was placed in the center of the petri dish. All petri dishes were placed in a microbial incubator (ThermoFisher 50125590) for 24 hours. Each test included three replicates.

[0131] Table 1

[0132]

[0133] As shown in Table 1 and Figure 5 As shown, the gel patch containing paeonol (TGG-D) exhibits strong antibacterial activity, with an average inhibition zone diameter of 56 mm against MRSA and 55 mm against Escherichia coli. In contrast, the antibacterial activity of the PVA hydrogel (20 wt%) and the solvent-free gel without paeonol is negligible.

[0134] (5) Tissue adhesion test

[0135] Solvent-free gel patches (25 mm in diameter, 3 mm in thickness) prepared according to the methods in Examples 1-6 were fixed onto two pieces of pigskin (25 mm wide, 80 mm long). The adhesive area was a circle with a diameter of 25 mm. Before testing, the samples were sealed with plastic film and stored at 4°C for 24 hours. With both ends of the samples fixed, axial tension was performed using a tensile testing machine (A1-3000, GOTECH, Dongguan, China) equipped with a 500 N force sensor. All adhesion tests were repeated three times.

[0136] like Figure 6 As shown, increasing the amount of paeonol or the ratio of zein / polyacid helps to improve adhesion strength, with a maximum adhesion force of 16.4 kPa, and peeling the gel off the pigskin without adhesive hysteresis.

[0137] (6) Self-healing performance test

[0138] Two gel pieces were joined together. One gel was obtained according to the methods described in Examples 1-6, and the other gel was obtained by adding 0.05 parts of Rhodamine B to the methods described in Examples 1-6. The two gel pieces were joined together, and the self-healing status of the joined surface was observed after 30 minutes.

[0139] The self-healing properties of the solvent-free gel prepared according to the method of Example 4 were tested using a TA rheometer (DHR-2, USA) at 25°C and 10 rad / s with strain cycles between 1% and 150% for 600 s each.

[0140] like Figure 7 As shown, after a 30-minute self-repair process, the two gels can rebuild together. Figure 7 a). Stepwise repeated dynamic strain analysis showed that the TGG patch exhibits good self-healing performance, with the G' and G" values ​​remaining stable in each odd or even step. Figure 7 b). Two main intermolecular interactions, hydrogen bonding and hydrophobicity, contribute to the self-healing properties of the gel patch.

[0141] (7) Validation of therapeutic effect using a Kunming mouse model of skin eczema

[0142] Accurately weigh 2.5 g of 2,4-dinitrochlorobenzene (DNCB) and place it in a 50 mL volumetric flask. Add 12.5 mL of olive oil and 37.5 mL of acetone sequentially, and mix well to obtain a 5% (w / v) DNCB solution. Take 10 mL of this 5% DNCB solution as the sensitizing solution, dilute it with 10 mL of olive oil and 30 mL of acetone, and make up to volume in a 50 mL volumetric flask to obtain a 1% DNCB solution, which is used as the activation solution.

[0143] Thirty-two male Kunming mice, weighing 20–25 g, were used. The experiment was divided into four groups: a blank control group, a model group, a dexamethasone group (dose approximately 0.35 g / kg), and a solvent-free gel group prepared according to the method in Example 1 (circular discs, 2.4 cm in diameter, 3 mm thick, with a drug loading of approximately 30% of the total gel mass, equivalent to a paeonol dose of approximately 0.015 g / kg). The day before the experiment, the mice were shaved on their abdomen (2 cm × 2 cm). The blank control group received no treatment. The other three groups were sensitized the following day by applying 25 μL of 5% DNCB solution to the shaved area on their abdomen. One week later, the mice were shaved on their backs (2 cm × 2 cm), and the following day, 100 μL of 1% DNCB solution was applied to the shaved area on their backs for a second sensitization. This sensitization was repeated weekly for four weeks. Three days after the sensitization period, skin samples were taken from the backs of the mice for the drug intervention test. The dexamethasone group and the solvent-free gel group were treated externally on the shaved area of ​​mice, while the model group received no treatment after sensitization.

[0144] like Figure 8 As shown, both gel patches and dexamethasone treatment significantly reduced skin inflammation. However, the efficacy of dexamethasone ointment was not significant in the second and third weeks, with significant skin inflammation remaining. Therefore, compared to dexamethasone ointment, gel patches reduced the probability of eczema recurrence, which ensures the long-term pharmacological effect of paeonol.

[0145] It should be noted that although the technical solution of the present invention has been described with specific examples, those skilled in the art will understand that the present invention should not be limited thereto.

[0146] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A solvent-free gel loaded with paeonol, comprising a composition of paeonol and a solvent-free gel matrix; in, The solvent-free gel matrix composition comprises lipoic acid, prolyl protein, and polyacids; By weight, the gel matrix contains 2-5 parts of lipoic acid, 0.06-0.33 parts of prolysin and 0.06-0.16 parts of polyacid.

2. The solvent-free gel loaded with paeonol according to claim 1, characterized in that, The prolysin is zein, rye prolysin, or barley prolysin; and / or The polyacids mentioned are citric acid, tartaric acid, or malic acid.

3. The solvent-free gel loaded with paeonol according to claim 1 or 2, characterized in that, The weight ratio of paeonol to thioctic acid in the solvent-free gel matrix composition is 1:2-5.

4. The method for preparing a solvent-free gel loaded with paeonol according to any one of claims 1 to 3, comprising the following steps: (1) Grind paeonol, thioctic acid, prolysin and polybasic acid to 150-250 mesh, put them into a mold and heat to melt; (2) The product obtained in (1) is swollen with an alcohol-water mixture, the solution is removed, the product is heated to remove bubbles, and then cooled to obtain the finished product.

5. The preparation method according to claim 4, characterized in that, The heating and melting temperature is 70~100℃; and / or The heating and melting time is 0.5~1h.

6. The preparation method according to claim 4 or 5, characterized in that, The alcohol-water mixture contains 50-75% v / v ethanol and 50-25% v / v water; and / or The mass ratio of paeonol to the alcohol-water mixture is 1:3 to 1:

5.

7. The preparation method according to claim 4 or 5, characterized in that, The swelling time is 10-30 minutes.

8. The preparation method according to claim 4 or 5, characterized in that, The heating and degassing time is 0.5~2 hours.

9. The use of the solvent-free gel loaded with paeonol according to any one of claims 1 to 3, or the solvent-free gel loaded with paeonol prepared by the preparation method according to any one of claims 4 to 8, in the preparation of a medicament for treating skin eczema.

Images