Paeonol-loaded solvent-free gel as well as gel matrix, preparation method and application thereof

Abstract

The invention provides paeonol-loaded solvent-free gel as well as a gel matrix, a preparation method and application thereof, the gel matrix comprises lipoic acid, prolamin and polybasic acid, and the method for preparing the solvent-free gel by loading paeonol on the gel matrix comprises the following steps: (1) mixing, heating and melting paeonol and a gel matrix composition; and (2) swelling the product obtained in the step (1) with an alcohol-water mixture, removing the solution, heating, defoaming, and cooling. The invention has the advantages of green and non-toxic raw materials, simple preparation process and low cost, is suitable for loading a large amount of paeonol, and can effectively realize the transdermal slow release of paeonol. Animal clinical experiments prove that the obtained gel patch has an application prospect in the aspect of skin eczema treatment.

Description

Technical Field

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

[0002] Paeonol, also known as peony phenol, is a bioactive substance extracted from the traditional Chinese medicine moutan bark (dried root bark of peony) or cynanchum chinense (dried root and rhizome of cynanchum chinense). It has anti-inflammatory, anti-diabetic, cardiovascular and cerebrovascular improvement, anti-tumor, neuroprotective and other effects, and can be used to treat a variety of skin diseases [Food Chem.2021,365,130384]. However, the application of paeonol as a clinical drug is relatively limited. The reason is that paeonol has poor water solubility and fast metabolism, resulting in low bioavailability. In this regard, it can be loaded through a polymer matrix to achieve sustained release and long-term administration, thereby improving bioavailability. However, in practical applications, it is usually faced with the problem of low loading.

[0003] In order to increase the loading capacity of paeonol, modern research has introduced hydrogels for solubilization [Life Sci. 2020, 250, 117544]. However, hydrogels with water as the continuous medium cannot break through the limitations of water volatilization in practical applications. This process often leads to gel network collapse and colloid aging, accompanied by decreased mechanical properties, decreased tissue adhesion, and loaded drug overflow [Angew. Chem., Int. Ed. 2022, 134 (4), e202115021]. In addition, hydrogels often face limitations such as low loading capacity of fat-soluble drugs and poor stability, which limits their application in the field of drug sustained release [Appl. Mater. Today 2018, 12, 294-308]. Although researchers have tried to overcome the limitations of hydrogel dehydration and low lipophilic drug loading by using methods such as solvent replacement and oil-water interface coating, these improvement measures often face lengthy molecular modification steps or time-consuming synthesis routes [Adv. Func. Mater. 2018, 28(49), 1800793]. Therefore, people are in urgent need of a new gel system to break through the bottleneck of hydrogel dehydration deformation and narrow application range of loaded drugs, so as to be used for complex and varied application conditions and pathological requirements. Summary of the invention

[0004] Problem that the invention aims to solve

[0005] The biggest limitation of paeonol as a clinical drug is its poor water solubility and rapid metabolism, which results in low bioavailability. Modern research has tried to achieve sustained release and long-acting drug delivery through loading with polymer matrices, but when using a hydrogel system, it faces problems such as easy dehydration and deformation of the colloid, low loading of fat-soluble drugs, poor stability, and complex solvent replacement steps.

[0006] Solutions for solving problems

[0007] Sulfur is abundant in nature and inexpensive. Disulfide bonds (SS) can undergo dynamic, reversible chemical cross-linking under high temperature, ultraviolet, and anion catalysis conditions, and the resulting polysulfide can also be miscible with a variety of substances or materials in the absence of solvents. In addition, most biological proteins have sulfhydryl groups and disulfide bonds, which can participate in SS dynamic cross-linking to obtain a new gel system, which is of great significance in improving tissue adhesion and obtaining green pharmaceutical products. Therefore, the gel network with organic SS as the main body is not only expected to increase the loading capacity of fat-soluble or poorly soluble drugs in water, but also has the potential to be used as a new topical preparation for the treatment of various skin diseases.

[0008] Preliminary exploratory experiments have shown that lipoic acid can be dissolved with drugs such as paeonol, cinnamic acid, and storax at 70°C to form a homogeneous solution. Moreover, lipoic acid and alcohol-soluble proteins can participate in SS dynamic cross-linking to obtain a new gel system. Therefore, a gel network based on a covalent cross-linked network based on disulfide bonds (formed by the sulfhydryl radical-sulfhydryl reaction between lipoic acid and alcohol-soluble proteins) is expected to solve the problems faced by existing technologies.

[0009] [1] The present invention first provides a solvent-free gel matrix composition, which comprises lipoic acid, prolamin and polyacid;

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

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

[0012] The alcohol-soluble protein is zein, secalin or hordein; and / or

[0013] The polyacid is citric acid, tartaric acid or malic acid.

[0014] [3] Use of the solvent-free gel matrix composition according to [1] or [2] in preparing a solvent-free gel;

[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 fat-soluble drug;

[0017] Further 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 the solvent-free gel matrix composition according to [1] or [2];

[0019] Preferably, the weight ratio of the paeonol to the lipoic 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] comprises the following steps:

[0021] (1) Grinding paeonol, lipoic acid, prolamin and polyacid to 150-250 mesh, putting into a mold, and heating to melt;

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

[0023] [6] The preparation method according to [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 added amount of paeonol to the alcohol-water mixture is 1:3 to 1:5.

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

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

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

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

[0033]

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

[0034] 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 preparation method of the solvent-free gel loaded with paeonol of the present invention adopts the method of grinding and heating to simultaneously complete the polymerization reaction and gelation. Meanwhile, lipoic acid can be mutually soluble with paeonol after melting, thereby increasing the loading amount of paeonol.

[0037] (3) The size, morphology and properties of the solvent-free gel loaded with paeonol of the present invention are stable, there is no collapse and aging problem caused by solvent volatilization, and it has the properties of stretchability, antibacterial, tissue adhesion, self-repair, etc.

[0038] (4) The solvent-free gel loaded with paeonol of the present invention can release paeonol slowly through transdermal administration and be used for treating skin eczema. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0040] Figure 2 This is the infrared spectrum of the solvent-free gel in Example 1 of the present invention.

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

[0042] Figure 4 1 is the tensile curve of the solvent-free gel in Examples 1 to 6 of the present invention.

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

[0044] Figure 6 The adhesion curves (a) and adhesion statistics (b) of the solvent-free gels in Examples 1 to 6 of the present invention to pig skin.

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

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

[0047] Fig. 9 The present invention is a schematic diagram of the preparation process of the solvent-free gel loaded with paeonol. DETAILED DESCRIPTION

[0048] Various exemplary embodiments, features and aspects of the present invention will be described in detail below. The word "exemplary" used here means "used as an example, embodiment or illustrative". Any embodiment described here as "exemplary" is not necessarily interpreted as being superior or better than other embodiments.

[0049] In addition, in order to better illustrate the present invention, numerous specific details are provided in the following specific embodiments. It should be understood by those skilled in the art that the present invention can be implemented without certain specific details. In other examples, methods, means, equipment and steps well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present invention.

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

[0051] In this specification, the word "may" means both performing a certain process and not performing a certain process.

[0052] In this specification, the references to "some specific / preferred embodiments", "other specific / preferred embodiments", "embodiments", etc. refer to specific elements (e.g., features, structures, properties and / or characteristics) related to the embodiments described herein, which are included in at least one embodiment described herein, and may or may not exist in other embodiments. In addition, it should be understood that the elements may be combined in various embodiments in any suitable manner.

[0053] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints numerical values ​​A and B.

[0054] In this specification, when "normal temperature" or "room temperature" is used, the temperature may be 10-40°C.

[0055] <First aspect>

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

[0057] In parts by weight, the gel matrix comprises 2-5 parts of lipoic acid, 0.06-0.33 parts of prolamin and 0.06-0.16 parts of polyacid.

[0058] In some specific embodiments, the solvent-free gel matrix composition consists of lipoic acid, prolamin, and polyacid.

[0059] Lipoic Acid

[0060] Lipoic acid is also known as DL-lipoic acid, and its molecular formula is C8H 14 O2S2, its structural formula is:

[0061]

[0062] Lipoic acid is an organic sulfide that can act as a coenzyme to participate in the acyl transfer in the metabolism of substances in the body, and can eliminate free radicals that accelerate aging and cause disease. Lipoic acid enters cells after being absorbed through the intestines in the body, and has the characteristics of both fat solubility and water solubility.

[0063] In the present invention, lipoic acid is used as a polymerization monomer, and ring-opening polymerization occurs when heated to generate sulfur free radicals, which can form a covalent gel network by disulfide cross-linking with the following alcohol-soluble proteins.

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

[0065] Prolamin

[0066] Prolamin is one of the components of plant seed storage proteins and is found in wheat and corn. Prolamin has strong water resistance, heat resistance and fat resistance and is widely used in food, medicine, textile, papermaking and other industries. Prolamin can also be used to produce bioactive peptides through enzymatic methods, which can be used in pharmaceuticals.

[0067] In the present invention, the prolamin is used as a chemical crosslinking agent, and the sulfhydryl groups contained in the prolamin generate sulfhydryl radicals at high temperature, which undergo disulfide crosslinking with the lipoic acid to form a covalent gel network. In some specific embodiments, the prolamin can be zein, rye prolamin or hordein.

[0068] Polyacid

[0069] In the present invention, the polyacid is used as a supramolecular crosslinking agent. Due to its strong acidity, it can form hydrogen bonds with the carboxyl group of the lipoic acid, thereby improving the excipient property and mechanical strength of the gel. In some specific embodiments, the polyacid can be citric acid, tartaric acid or malic acid.

[0070] Citric acid, also known as citric acid, has a molecular formula of C6H8O7 and a structural formula of:

[0071]

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

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

[0074]

[0075] Tartaric acid exists 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 make food sour. The largest use of tartaric acid is as a beverage additive and also as a raw material in the pharmaceutical industry.

[0076] Malic acid, also known as 2-hydroxysuccinic acid, has a chemical formula of C4H6O5 and a structural formula of:

[0077]

[0078] Malic acid exists in almost all fruits, with the largest amount in pome fruits. Malic acid is a colorless needle-shaped crystal or white crystalline powder, odorless, with a pungent and refreshing sour taste. It is an important intermediate product in the internal circulation of the human body and is easily absorbed by the human body. Therefore, it is widely used in food, cosmetics, medical and health products as an excellent food additive and functional food.

[0079] <Second Aspect>

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

[0081] In some specific embodiments, 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 lipophilic drug.

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

[0084] <Third Aspect>

[0085] In the third aspect of the present 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 the paeonol to the lipoic 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 the Ranunculaceae plant peony, with the structural formula:

[0089]

[0090] Paeonol has sedative, hypnotic, antibacterial, anti-inflammatory, antioxidant, and blood pressure lowering effects. In daily chemicals, it can inhibit the intracellular O 2- The free radicals produced can whiten the skin, reduce the pigmentation in the skin, remove stasis and remove spots; it also has anti-inflammatory, anti-swelling and analgesic, anti-allergic and anti-viral effects. It has good therapeutic and health care effects on pigmentation, muscle pain, skin itching, psoriasis, herpes zoster and eczema. In addition, it has a good effect in toothpaste, mouthwash, tooth powder and toothache water.

[0091] <Fourth Aspect>

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

[0093] (1) Grinding paeonol, lipoic acid, prolamin and polyacid to 150-250 mesh, putting into a mold, and heating to melt;

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

[0095] In some specific embodiments, the heating and melting temperature is 70-100°C, for example, 70°C, 80°C, 85°C, 90°C, 100°C, etc.

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

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

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

[0099] In some specific embodiments, the swelling time is 10 to 30 min, for example, 10 min, 15 min, 20 min, 25 min, 30 min, etc.

[0100] In some specific embodiments, the heating 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 embodiments, the heating and stripping time is 1 to 2 hours.

[0102] <Fifth Aspect>

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

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

[0105] The technical scheme of the present invention will be described in detail below in conjunction with the examples, but those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. If no specific conditions are specified in the examples, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be obtained commercially.

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

[0107] Example 1

[0108] 1 part (1 g each) of paeonol, 3 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 to melt at 90°C for 0.5 h. Subsequently, 3 parts of 75% alcohol solution were added to soak for 10 min for swelling, and after removing the solution, the mixture was heated at 90°C for 1 h for degassing, and cooled to room temperature to obtain a finished product (referred to as TGG-A).

[0109] Example 2

[0110] 1 part (1 g each) of paeonol, 2 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 to melt at 100°C for 1 hour. Then 4 parts of 55% alcohol solution were added to soak for 30 minutes for swelling, and after removing the solution, it was heated at 100°C for 1 hour again for degassing, and cooled to room temperature to obtain a finished product (referred to as TGG-B).

[0111] Example 3

[0112] 1 part (1 g each) of paeonol, 5 parts of lipoic acid, 0.20 parts of ryegrass protein and 0.10 parts of malic acid were ground and mixed evenly, placed in a polypropylene mold, and heated to melt at 70°C for 0.8 h. Subsequently, 3 parts of 60% alcohol solution were added to soak for 20 min for swelling, and after removing the solution, the mixture was heated at 75°C for 2 h for degassing, and cooled to room temperature to obtain a finished product (referred to as TGG-C).

[0113] Example 4

[0114] 1 part (1 g each) of paeonol, 2.5 parts of lipoic acid, 0.30 parts of hordein and 0.08 parts of citric acid were ground and mixed evenly, placed in a polypropylene mold, and heated to melt at 80°C for 0.6 h. Subsequently, 5 parts of 70% alcohol solution were added to soak for 15 min for swelling, and after removing the solution, the mixture was heated at 80°C for 1 h for degassing, and cooled to room temperature to obtain a finished product (referred to as TGG-D).

[0115] Example 5

[0116] 1 part (1 g 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 to melt at 100°C for 1 hour. Subsequently, 3 parts of 75% alcohol solution were added to soak for 10 minutes for swelling, and after removing the solution, the mixture was heated at 100°C for 1.5 hours for degassing, and cooled to room temperature to obtain a finished product (referred to as TGG-E).

[0117] Example 6

[0118] 1 part (1 g each) 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 to melt at 85°C for 0.5 h. Then, 5 parts of 55% alcohol solution were added to soak for 30 min for swelling, and after removing the solution, the mixture was heated at 85°C for 1.8 h for degassing, and cooled to room temperature to obtain a finished product (referred to as TGG-F).

[0119] Performance test experiment

[0120] (1) Infrared test

[0121] The dried KBr was ground together with paeonol, citric acid, zein, lipoic acid or the lyophilized powder of the gel in Example 1, placed in a metal mold, and pressure was applied to form a KBr pellet, which was then placed in a Frontier infrared spectrometer for measurement. Figure 2 As shown, the obtained gel has peaks at 2925, 2858 and 1696 cm -1 The characteristic peaks similar to those of lipoic acid appear, corresponding to the aliphatic CH stretching vibration peak and carboxyl peak of lipoic acid. Located at 3100-3700cm -1 The strong broad peaks correspond to the OH stretching vibration peaks, which are derived from the hydroxyl groups of zein and paeonol. The grinding-thermal gel has characteristic peaks of paeonol acyl (-COCH3) and Ar-O-CH3, which are located at 1628, 1252 and 1066 cm -1 , proving that the gel is loaded with paeonol.

[0122] (2) Swelling test

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

[0124] The results showed that the gel did not dissolve in different solvents, indicating that the gel was chemically cross-linked during the preparation process to form a stable polymer network structure. The swelling rate of the gel in 75% alcohol was 20%, the swelling rate in ethanol was 10%, and it did not swell at all in water. The above results show 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, 3 mm thick) were prepared in polypropylene molds according to the methods in Examples 1 to 6. The mechanical properties of the gels were measured by a tensile testing machine (Al-3000, GOTECH, Dongguan, China) equipped with a 500 N load cell, with the following parameters: the tensile speed was 100 mm / min and the initial gauge length was 15 mm.

[0127] like Figure 4As shown, the average tensile strength of the gel is between 21KPa and 29KPa, and the elongation at break can reach 3000%-6000%, wherein the increase in the proportion of paeonol will lead to a decrease in tensile strength. At the same time, the increase in the amount of zein and polyacid crosslinker will increase the tensile strength. The increase in the polyacid content will lead to a significant increase in the maximum elongation at break.

[0128] (4) Inhibition zone test

[0129] Luria-Bertani (LB) medium was prepared by adding 10 g of tryptone, 5 g of yeast extract, 10 g of sodium chloride, and 10 g of agar to 950 mL of deionized water. The pH of the mixture was adjusted to 7.0 by titrating sodium hydroxide solution (5 M). The volume of the LB medium was then increased to 1 L by adding deionized water. The medium was placed in a high-pressure steam autoclave (121 ° C, 0.1 MPa) for 20 min. After that, the medium was placed on a clean bench, cooled to 40 ° C, and after gently shaking, the LB medium was poured into a bacterial culture dish and allowed to stand until the medium solidified. 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 ring test, the concentration of the bacterial solution was adjusted to 5×10 8 CFU / mL.

[0130] Polyvinyl alcohol (PVA) was dissolved in pure water at 90°C for 1h and then subjected to a freeze-thaw cycle of 6h to obtain PVA hydrogel (20wt%). Before testing, the gel (PVA hydrogel, solvent-free gel without paeonol, and solvent-free gel containing paeonol prepared according to the method of Example 4) was treated with 75% ethanol solution. After sterilization and dissolution with distilled water, LB culture medium was poured into a culture dish and spread on a flat plate. Subsequently, the bacterial solution was introduced into the culture medium and cultured until solidified. A gel disc (diameter 12mm, thickness 3mm) was placed in the center of the culture dish. All culture dishes were placed in a microbial incubator (ThermoFisher 50125590) for 24h. Each test contained three parallel samples.

[0131] Table 1

[0132]

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

[0134] (5) Tissue adhesion test

[0135] Solvent-free gel patches (25 mm in diameter and 3 mm in thickness) prepared according to the methods of Examples 1 to 6 were fixed on two pieces of pig skin (25 mm in width and 80 mm in length). The bonding 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 h. The samples were fixed at both ends and axially stretched using a tensile testing machine (Al-3000, GOTECH, Dongguan, China) equipped with a 500N force sensor. All adhesion tests were repeated three times.

[0136] like Figure 6 As shown, increasing the amount of paeonol added or the zein / polyacid ratio helps to improve the adhesion strength, with the maximum adhesion reaching 16.4 KPa, and no adhesion hysteresis occurs when the gel is peeled off from the pig skin.

[0137] (6) Self-healing performance test

[0138] Two pieces of gel were spliced, one of which was obtained according to the method in Examples 1 to 6, and the other was obtained by adding 0.05 parts of rhodamine B to Examples 1 to 6. The two pieces of gel were spliced, and the self-healing condition of the spliced ​​surface was observed after 30 minutes.

[0139] The self-healing properties of the solvent-free gel prepared according to 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%, with each cycle lasting 600 s.

[0140] like Figure 7 As shown, after a 30-minute self-healing process, the two gels can be reconstructed together ( Figure 7 a). The step-by-step repeated dynamic strain analysis shows that the TGG patch has good self-healing properties, where the G' and G" values ​​remain stable in each odd or even step ( Figure 7 b). Two major intermolecular interactions, hydrogen bonding and hydrophobicity, contribute to the self-healing properties of the gel patch.

[0141] (7) Kunming mouse skin eczema model to verify the therapeutic effect

[0142] Weigh 2.5g of 2,4-dinitrochlorobenzene (DNCB) accurately and place it in a 50mL volumetric flask. Add 12.5mL of olive oil and 37.5mL of acetone in turn and mix well to obtain a 5% (w / v) DNCB solution. Take 10mL of the 5% DNCB solution as the sensitizing solution, dilute it with 10mL of olive oil and 30mL of acetone and add it to a 50mL volumetric flask to obtain a 1% DNCB solution as the stimulating solution.

[0143] 32 male Kunming mice, weighing 20-25g. The experiment was divided into 4 groups: blank control group, model group, dexamethasone group (dosage of about 0.35g / kg) and solvent-free gel group prepared according to the method in Example 1 (disc, diameter 2.4cm, thickness 3mm, drug loading of about 30% of the total mass of gel, equivalent to a dosage of paeonol of about 0.015g / kg). The day before the experiment, the abdomen of the mice was shaved (2cm×2cm), the blank control group was not treated in any way, and the other three groups were sensitized by applying 25μL 5% DNCB solution to the shaved area of ​​the abdomen the next day, and shaved the back of the mice (2cm×2cm) one week later, and 100μL 1% DNCB solution was applied to the shaved area of ​​the back the next day for the second sensitization, so that sensitization was performed once a week for 4 consecutive weeks. Three days after the end of sensitization, the back skin of the mice was taken for drug intervention test. The mice in the dexamethasone group and the solvent-free gel group were given topical application on the shaved areas, while the model group received no treatment after sensitization.

[0144] like Figure 8 As shown, the gel patch and dexamethasone treatment significantly reduced skin inflammation. However, the efficacy of dexamethasone ointment was not significant in the second and third weeks, and a large amount of skin inflammation was still not eliminated. Therefore, compared with dexamethasone ointment, the gel patch reduced the probability of eczema recurrence, which ensured the long-term pharmacological effect of paeonol.

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

[0146] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A solvent-free gel matrix composition comprising lipoic acid, prolamin and polyacid; Preferably, the gel matrix comprises 2-5 parts of lipoic acid, 0.06-0.33 parts of prolamin and 0.06-0.16 parts of polyacid, in parts by weight.

2. The solvent-free gel matrix composition according to claim 1, characterized in that The alcohol-soluble protein is zein, secalin or hordein; and / or The polyacid is citric acid, tartaric acid or malic acid.

3. Use of the solvent-free gel matrix composition according to claim 1 or 2 in preparing a solvent-free gel; Preferably, the solvent-free gel is a drug-loaded solvent-free gel; More preferably, the solvent-free gel is a solvent-free gel loaded with a fat-soluble drug; Further preferably, the solvent-free gel is a solvent-free gel loaded with paeonol.

4. A solvent-free gel loaded with paeonol, which is made of paeonol and the solvent-free gel matrix composition according to claim 1 or 2; Preferably, the weight ratio of the paeonol to the lipoic acid in the solvent-free gel matrix composition is 1:2-5.

5. The method for preparing the solvent-free gel loaded with paeonol according to claim 4, comprising the following steps: (1) Grinding paeonol, lipoic acid, prolamin and polyacid to 150-250 mesh, putting into a mold, and heating to melt; (2) The product obtained in (1) is swollen with an alcohol-water mixture, the solution is removed, and then heated for degassing, and cooled to obtain a finished product.

6. The preparation method according to claim 5, characterized in that: The heating and melting temperature is 70-100°C; and / or The heating and melting time is 0.5 to 1 hour.

7. The preparation method according to claim 5 or 6, 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 the paeonol to the alcohol-water mixture is 1:3 to 1:

5.

8. The preparation method according to any one of claims 5 to 7, characterized in that: The swelling time is 10 to 30 minutes.

9. The preparation method according to any one of claims 5 to 8, characterized in that: The heating degassing time is 0.5 to 2 hours.

10. Use of the solvent-free gel loaded with paeonol according to claim 4 or the solvent-free gel loaded with paeonol prepared by the preparation method according to any one of claims 5 to 9 in the preparation of a drug for treating skin eczema.

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