A medicine-carrying integrated smilax glabra modified starch drug delivery system, a preparation method and application thereof

Abstract

This invention provides a drug-carrying, integrated drug delivery system for modified Smilax glabranch starch, its preparation method, and its application, belonging to the field of pharmaceutical technology. The drug delivery system uses fresh Smilax glabranch starch as raw material. The PUL enzymatic method is used to debranch the starch, increasing the synthetic sites to reduce the clinical dosage. Hydroxybutyrylation modification and a "top-down" technique are used to form a uniform and stable drug-carrying, integrated drug delivery system for modified Smilax glabranch starch. The application is in the preparation of drugs for treating atopic dermatitis. This invention has the following advantages: debranched Smilax glabranch starch has multiple exposure sites, significantly improving butyrylation efficiency and resulting in a smaller dosage; the system can achieve colonic targeting, providing butyric acid through both endogenous and exogenous sources, achieving a dual release effect of immediate and controlled butyric acid production; the particle size is small, the distribution is uniform, the system is stable, and the PDI is 0.05~0.30; it effectively treats atopic dermatitis by reducing the inflammatory response.

Description

Technical Field

[0001] This invention belongs to the field of pharmaceutical technology, specifically relating to a drug-carrying modified starch delivery system based on Smilax glabra, its preparation method, and its application, and particularly to a drug-carrying modified starch based on Smilax glabra for treating atopic dermatitis, its preparation method, and its application. Background Technology

[0002] Atopic dermatitis (AD) is a prevalent immune-inflammatory skin disease that severely impacts patients' quality of life, and its incidence continues to rise. Clinically, it is difficult to cure and has a high recurrence rate, making it a hot area of ​​research and development internationally. In recent years, with the introduction of biologics such as dupilumab and small-molecule JAK inhibitors such as abuxitinib, the treatment options for AD have been greatly enriched, but significant clinical needs remain unmet. Traditional Chinese medicine is one of the ten advantageous treatments for AD, but currently, no blockbuster products similar to those found in Western medicine have emerged.

[0003] Smilax glabra, a traditional Chinese medicine, is known as the "King of Dampness-Removing Herbs." Its starch content can promote the production of short-chain fatty acids, such as butyric acid, in the body, thus reducing inflammation. However, the treatment course is long and the activity is weak. Studies have shown that Smilax glabra starch is rich in linear chains, providing a good structural basis for modification. Drug delivery is an important concept in the field of drug delivery, referring to a material or system that simultaneously possesses the dual functions of a drug carrier and an active drug. However, several challenges remain in clinical applications: the butyrylation modification of Smilax glabra starch has limited binding sites, resulting in large clinical doses and making it difficult to prepare modern dosage forms such as capsules; it also fails to mask the unpleasant odor of butyric acid. Furthermore, its large particle size and strong hydrophobicity lead to poor dispersibility and limited surface area, thus affecting the release efficiency of butyric acid. Summary of the Invention

[0004] To address the problems existing in the prior art, the first objective of this invention is to disclose a drug delivery system integrating Smilax glabra modified starch (BSGS NPs).

[0005] This drug-carrier integrated Smilax glabra starch delivery system uses fresh Smilax glabra starch as raw material. The PUL enzymatic debranching method increases the synthesis sites, reducing the clinical dosage of Smilax glabra starch. Hydroxybutyrylation modification and a "Top-Down" technique are used to form a uniform and stable drug-carrier integrated Smilax glabra starch delivery system. As a novel functional carrier derived from the traditional Chinese medicine Smilax glabra, it utilizes its anti-digestive properties to achieve colon-targeted delivery. Through slow digestion of starch, it targets the colon to release exogenous butyric acid and increases the relative abundance of butyric acid-producing bacteria to produce endogenous butyric acid. This dual provision of butyric acid directly acts on the "skin-gut axis," thereby exerting a therapeutic effect on atopic dermatitis.

[0006] This invention utilizes the PUL enzymatic debranching method to increase the number of hydroxyl exposure sites in Smilax glabra starch, significantly improving butyrylation efficiency and greatly reducing clinical dosage. It allows for the formulation of modern dosage forms such as capsules, masking the pungent odor of butyric acid and improving patient compliance. The system enables targeted colonic delivery of butyric acid through both endogenous and exogenous sources, achieving both immediate and controlled butyric acid production, and allows for monitoring of butyric acid generation. Employing "Top-Down" technology, it forms a uniform and stable drug-carrying Smilax glabra modified starch delivery system with small particle size, uniform distribution, and system stability, with a PDI of 0.05~0.30. This invention achieves a deep integration of the holistic regulation concept of traditional Chinese medicine with modern microecology and immune regulation theories, promoting a paradigm shift from "empirical application" to "precision regulation" of Smilax glabra, ultimately achieving effective treatment of atopic dermatitis by reducing inflammatory responses.

[0007] The second objective of this invention is to disclose a method for preparing the above-mentioned drug-carrier-integrated Smilax glabra modified starch drug delivery system.

[0008] The third objective of this invention is to disclose the application of the above-mentioned drug-carrying Smilax glabra modified starch drug delivery system.

[0009] The objective of this invention is achieved through the following technical solution: A drug-carrying, integrated Smilax glabranch modified starch drug delivery system, wherein: the drug-carrying, integrated Smilax glabranch modified starch drug delivery system uses fresh Smilax glabranch starch as raw material, PUL enzymatic debranching increases synthesis sites to reduce the clinical dosage of Smilax glabranch starch, hydroxybutyrylation modification, and top-down technology are used to form a uniform and stable drug-carrying, integrated Smilax glabranch modified starch drug delivery system; the PUL enzymatic debranching refers to treating the Smilax glabranch starch solution with PUL enzyme at room temperature; the hydroxybutyrylation modification refers to reacting an aqueous solution of debranched Smilax glabranch starch with a mass concentration of 30-50% w / v with butyric anhydride under constant temperature conditions; the top-down technology includes the steps of initially dispersing butyrylated Smilax glabranch resistant starch with PVPk30 using a high-speed shearing machine, and then performing nano-processing using a high-pressure homogenization method.

[0010] A method for preparing a drug-carrier-integrated Smilax glabra modified starch drug delivery system, wherein the preparation method includes the following steps: (1) Weigh out fresh Smilax glabra starch; (2) Dissolve Smilax glabra starch in a 0.2 mol / L acetic acid / sodium acetate buffer solution at pH 5.2 to prepare a 5-15% Smilax glabra starch milk; (3) Heat the above-mentioned Smilax glabra starch milk at 70~95℃ for 0.5 h to gelatinize it; (4) Cool the gelatinized Smilax glabra starch solution to room temperature, add 50~150 ASPU / g PUL enzyme for debranching treatment, and the debranching treatment time is 8~24 h; (5) Immediately after the reaction is complete, raise the temperature to 95℃ to inactivate the enzyme for 0.5 h to terminate the reaction; (6) Place the enzyme-inactivated Smilax glabra starch solution at 4~20℃ and allow it to coagulate for 6~12 h; (7) Wash the sample with distilled water and ethanol and filter it. Dry, crush and sieve (100 mesh) to obtain Smilax glabra starch. (8) Prepare a suspension by mixing debranched starch from Smilax glabra with water, with a mass concentration of 30-50% (w / v). (9) Place the debranched starch suspension of Smilax glabra in a constant temperature water bath at 30-40℃, and add NaOH solution while stirring to adjust the pH to 8-9; (10) Add butyric anhydride / ethanol (1:1, v / v) solution to the debranched starch suspension of Smilax glabra. The mass-volume ratio of starch to butyric anhydride is 1:0.5~1:1.8. (11) Place the suspension in a constant temperature water bath at 30-40°C and react for 3-5 h; (12) Terminate the reaction by adding HCl solution while stirring, and adjust the pH of the butyrylation reaction solution to 6.5-7.5; (13) The solution obtained from the reaction was subjected to sedimentation, washing and drying to obtain modified starch from Smilax glabra; (14) Mix the modified starch of Smilax glabra with deionized water to prepare an aqueous solution of modified starch of Smilax glabra with a mass concentration of 3-5% (w / v); (15) Gradually add 0.5~1.0% (w / v) of polyvinylpyrrolidone (PVP K30) powder to the aqueous solution of Smilax glabra modified starch; (16) Transfer the above mixed solution to a high-speed shearing machine, set the shearing speed to 10,000~13,000 rpm and the shearing time to 3~7 min, so as to achieve the initial dispersion of Smilax glabra modified starch and PVP K30. (17) The initially dispersed solution was transferred to a high-pressure homogenizer and the homogenization pressure was set to 80~120 MPa. The homogenization process was carried out for 8~15 cycles, followed by freeze-drying to complete the preparation of the drug-carrying Smilax glabra modified starch drug delivery system.

[0011] The above-described technical solution describes a drug-carrier-integrated Smilax glabra modified starch drug delivery system.

[0012] The drug-carrying modified starch drug delivery system of Smilax glabra as described above has the following characteristics: the RS rate of the drug-carrying modified starch drug delivery system is 38%~65%; in the ¹H-NMR spectrum, characteristic signal peaks exist at 0.90 ppm methyl, 2.31 ppm methylene and 1.55 ppm methylene, and the degree of substitution is 0.12~0.29.

[0013] The drug-carrier-integrated Smilax glabra modified starch drug delivery system described in the above technical solution, wherein: in the FT-IR spectrum of the drug-carrier-integrated Smilax glabra modified starch drug delivery system, at 1739 cm⁻¹... -1 Absorption peaks are present at 15.23°, 17.18° and 23.02° in the XRD diffraction pattern; C-type crystal structure diffraction peaks are present at 15.23°, 17.18° and 23.02°; thermogravimetric analysis results show good thermal stability.

[0014] The drug-carrier-integrated Smilax glabra modified starch drug delivery system described in the above technical solution has an average particle size of 150~400 nm and a PDI of 0.05~0.30.

[0015] The application of the drug-carrier-integrated Smilax glabra modified starch drug delivery system described above in the preparation of drugs for treating atopic dermatitis.

[0016] In the application described in the above technical solution, the atopic dermatitis refers to atopic dermatitis induced by sensitizers, including ovalbumin, DNCB and / or house dust mites.

[0017] In the application described above, the integrated drug-carrier Smilax glabra modified starch drug delivery system is an oral preparation; the oral preparation is preferably one of capsules or tablets.

[0018] The application described in the above technical solution refers to the integrated drug delivery system made from Smilax glabra modified starch having at least one of the following uses: (1) It releases butyrate in the colon, regulates the gut microbiota, and increases butyrate levels in the body; (2) Reduce the levels of inflammatory factors TNF-α and IL-6 in serum and skin; (3) Increase the content of anti-inflammatory factor IL-10 in serum and skin.

[0019] In this technical solution, the drug delivery system using Smilax glabra modified starch releases butyric acid in the colon, regulates the intestinal microbiota, enhances butyric acid production, reduces inflammatory response, and treats atopic dermatitis.

[0020] The present invention has the following beneficial effects: 1. This invention provides a method for preparing a drug-carrying, integrated Smilax glabranch modified starch drug delivery system. Utilizing the PUL enzymatic debranching method, the hydroxyl groups of Smilax glabranch starch are exposed at multiple sites. The hydroxyl groups then undergo esterification with butyric anhydride under alkaline conditions to generate modified Smilax glabranch starch. This achieves colon-targeted, endogenous and exogenous dual supply of butyric acid, solving the problem of premature absorption of butyrate in the small intestine and significantly reducing the clinical dosage. In particular, this invention employs a "Top-Down" technique to form a uniform and stable drug-carrying, integrated Smilax glabra modified starch drug delivery system with small particle size, uniform distribution, and system stability. This allows for the formulation of modern dosage forms such as capsules, masking the pungent odor of butyric acid and improving patient compliance.

[0021] 2. This invention also provides the application of the above-mentioned drug-carrying Smilax glabra modified starch drug delivery system in the treatment of atopic dermatitis. The results show that the drug-carrying Smilax glabra modified starch drug delivery system has a good therapeutic effect on atopic dermatitis, providing a new approach for the subsequent treatment of atopic dermatitis. Attached Figure Description

[0022] Figure 1 A schematic diagram of the entire process for preparing a drug-carrier-integrated Smilax glabra modified starch drug delivery system; Figure 2 Images of Smilax glabra (Tufuling) as a medicinal material and Smilax glabra modified starch are shown; 2A is the image of Smilax glabra as a medicinal material, and 2B is the image of Smilax glabra modified starch. Figure 3 Characterization images of the drug delivery system using Smilax glabra modified starch; where A is a SEM image; B is... 1 C is H-NMR; D is FT-IR; E is XRD; F is TGA; DTG. Figure 4 This is a particle size distribution diagram of the Smilax glabra-modified starch drug delivery system integrated with the drug carrier in Example 1; Figure 5 A diagram illustrating the mechanism by which the Smilax glabra-modified starch drug delivery system, which integrates drug delivery, targets and regulates the gut-brain axis to exert its anti-atopic dermatitis effect. Figure 6 The pharmacodynamics of the drug-carrying Smilax glabra modified starch drug delivery system for the treatment of atopic dermatitis is shown in the figure. A is a representative dorsal skin image of mice, B is the clinical skin score, C is the weight change, D is a HE-stained dorsal skin tissue section (scale bar 100 μm) and epidermal thickness, and E is a toluidine blue-stained skin section (scale bar 100 μm) and mast cell density. Figure 7This diagram illustrates the mechanism by which the drug-carrier-integrated Smilax glabra modified starch delivery system reduces systemic inflammation; where A represents the IL-6 level in the skin, B represents the IL-10 level in the skin, C represents the TNF-α level in the serum, D represents the IL-10 level in the serum, E represents the butyric acid content in the colonic contents, and F represents the total SCFA content in the colonic contents. Detailed Implementation

[0023] To facilitate understanding of the technical solution of the present invention, the preparation method and application of the drug-carrying modified starch drug delivery system of Smilax glabra integrated with the present invention will be further explained below with reference to specific embodiments.

[0024] Example 1: Preparation of a drug delivery system using Smilax glabra-modified starch as the integrated drug carrier: The technical route for preparing a drug delivery system using Smilax glabra-modified starch is as follows: Figure 1 As shown: Using fresh Smilax glabranch starch as raw material, Smilax glabranch debranch starch was prepared by PUL enzyme. Butyrylation modification technology was used to react Smilax glabranch debranch starch with butyric anhydride in a constant temperature water bath under alkaline conditions to prepare modified Smilax glabranch starch. The "Top-Down" technology was used to further form a uniform and stable Smilax glabranch modified starch drug delivery system.

[0025] Unless otherwise specified, the present invention does not have special requirements for the raw materials used in the preparation, and commercially available products well known to those skilled in the art can be used.

[0026] The preferred origin of the Smilax glabra in this invention is Guangxi ( Figure 2 A), purchased from the Chunyi Anran Chinese Medicinal Herb Planting Professional Cooperative in Fanshi County.

[0027] The specific operating steps are as follows: (1) Weigh out fresh Smilax glabra starch; (2) Dissolve Smilax glabra starch in a 0.2 mol / L acetic acid / sodium acetate buffer solution at pH 5.2 to prepare a 10% Smilax glabra starch milk; (3) The above-mentioned Smilax glabra starch milk was heated at 95°C for 0.5 h to gelatinize; (4) Cool the gelatinized Smilax glabra starch solution to room temperature, add 80 ASPU / g PUL enzyme for debranching treatment, and the debranching treatment time is 12 h; (5) Immediately after the reaction is complete, raise the temperature to 95℃ to inactivate the enzyme for 0.5 h to terminate the reaction; (6) Place the enzyme-inactivated Smilax glabra starch solution at 20℃ and allow it to coagulate for 8 hours; (7) Wash the sample with distilled water and ethanol and filter it. Dry, crush and sieve (100 mesh) to obtain Smilax glabra starch. (8) Prepare a starch suspension by mixing debranched starch from Smilax glabra with water, with a mass concentration of 40% (w / v). (9) Place the debranched starch suspension of Smilax glabra in a 37°C constant temperature water bath, and add NaOH solution while stirring to adjust the pH to 8.5; (10) Add butyric anhydride / ethanol (1:1, v / v) solution to the debranched starch suspension of Smilax glabra. The mass-volume ratio of starch to butyric anhydride is 1:1.2. (11) Place the suspension in a 37°C constant temperature water bath and react for 3.5 h; (12) Terminate the reaction by adding HCl solution while stirring to adjust the pH of the butyrylation reaction solution to 7. (13) The solution obtained from the reaction was subjected to sedimentation, washing and drying to obtain modified starch from Smilax glabra (Smilax glabra). Figure 2 B); (14) Mix the modified Smilax glabra starch powder with deionized water to prepare a 5% (w / v) aqueous solution of modified Smilax glabra starch. (15) Gradually add 1% (w / v) polyvinylpyrrolidone (PVP K30) powder to the aqueous solution of Smilax glabra modified starch; (16) The above mixed solution was transferred to a high-speed shear machine, and the shearing speed was set to 13,000 rpm and the shearing time was 5 min, so as to achieve the initial dispersion of Smilax glabra modified starch and PVP K30. (17) The solution after initial dispersion was transferred to a high-pressure homogenizer and the homogenization pressure was set to 100 MPa. The homogenization process was carried out for 12 cycles, followed by freeze-drying to obtain a drug-carrying modified starch drug delivery system.

[0028] The following experimental examples illustrate the preparation method and application of the drug delivery system based on modified Smilax glabra starch of the present invention, and its beneficial effects.

[0029] Example 1: Characterization of a drug delivery system using Smilax glabra-modified starch: (1) The sample from Example 1 was incubated with pancreatic α-amylase and glucosylamylase at 37°C. Samples were taken at 0, 20, and 120 minutes after the start of the reaction. Immediately after sampling, enzyme activity was terminated with anhydrous ethanol, and the amount of glucose released at each time point was determined using a GOPOD kit. The resistance rate RS (%) was calculated using the formula: RS (%) = 100% - RDS (%) - SDS (%), RDS (%) = (G... 20 -G0) × 0.9 / W, SDS (%) = (G 120 -G 20 G = 0.9 / W, where G0 is the glucose concentration (mg) measured at 0 minutes. 20 The glucose content (mg) measured at 20 minutes, G 120The glucose content (mg) was measured at 120 minutes, W was the dry weight (mg) of the starch sample used, RDS (%) was the percentage of rapidly digested starch, and SDS (%) was the percentage of slowly digested starch.

[0030] (2) Take the sample from Example 1, coat a thin gold film on its surface by sputtering, and observe the surface morphology of starch granules using a scanning electron microscope (SEM).

[0031] (3) Take the sample from Example 1, dissolve it in deuterated dimethyl sulfoxide (DMSO-d6), and collect its ¹H NMR spectrum using a nuclear magnetic resonance spectrometer. Calculate the degree of substitution (DS) using the formula. DS = 4A / (3B + A) Where A is the peak area of ​​the butyryl methyl proton (1.90-2.30 ppm) and B is the combined peak area of ​​the hydroxyl group and H-1 proton in the α-D-glucopyranose unit (>4.5 ppm).

[0032] (4) Take the sample from Example 1, grind it thoroughly with potassium bromide and press it into a translucent sheet, then heat it at 400–4000 cm⁻¹. -1 Fourier transform infrared spectroscopy (FT-IR) was performed in the mid-infrared band to analyze its functional group structure.

[0033] (5) Take the sample from Example 1 and perform X-ray diffraction (XRD) under Cu-Kα radiation at 40 kV and 40 mA to analyze its crystal structure characteristics.

[0034] (6) Take the sample from Example 1 and use a thermogravimetric analyzer (TGA) to test its thermal stability. At the same time, record the thermogravimetric (TG) curve and its corresponding differential thermogravimetric (DTG) curve.

[0035] (7) Take the sample from Example 1, dilute it appropriately with distilled water, and measure the particle size and PDI using a nanoparticle size analyzer. Repeat the measurement 3 times.

[0036] Experimental results: RS ratio was 57%. The particles exhibited relatively complete particle morphology (e.g., ...). Figure 3 As shown in Figure A). In the ¹H-NMR spectrum, new characteristic signals appeared at 0.90 ppm (methyl), 2.31 ppm (methylene), and 1.55 ppm (methylene), further confirming that the starch molecules underwent acylation modification (e.g., as shown in Figure A). Figure 3 As shown in Figure B), the degree of substitution (DS) calculated by the formula is 0.29. FT-IR spectral results show that at 1739 cm⁻¹... -1 A new absorption peak appears at [location], which can be attributed to the stretching vibration of the ester carbonyl (C=O) group, indicating that an ester bond structure has been successfully introduced into the starch molecule (e.g., [missing information]). Figure 3(As shown in C). XRD analysis results show that typical C-type crystal structure diffraction peaks are observed at 15.23°, 17.18°, and 23.02°, with a weak diffraction peak at 5.66°, indicating that butyrylation modification did not destroy the basic crystal structure of starch (as shown in C). Figure 3 (As shown in D). Thermogravimetric analysis results show that the material underwent three main thermal decomposition stages during the heating process, exhibiting good overall thermal stability; its DTG curve has a wide peak shape and a low peak value, indicating that the thermal degradation process of the material is relatively slow (e.g., Figure 3 E, Figure 3 (As shown in F). The average particle size is 150 ~ 400 nm, and the PDI is 0.05 ~ 0.30 (as shown in F). Figure 4 (As shown).

[0037] Experimental Example 2: Pharmacodynamic Study of a Drug Delivery System Integrating Smilax glabra-Modified Starch: The drug delivery system, which integrates Smilax glabra modified starch, targets and regulates the gut-brain axis to exert its anti-atopic dermatitis mechanism, as shown in the diagram. Figure 5 As shown. The specific research methods are as follows: 1. Animals: 24 male BALB / c mice, SPF grade, 8 weeks old, weighing 20±1 g.

[0038] 2. Reagents and equipment: 2,4-dinitrochlorobenzene (DNCB); mouse TNF-α, IL-6 and IL-10 ELISA kits; 4% paraformaldehyde solution; hematoxylin-eosin (HE) staining kit; toluidine blue staining kit; gas chromatography-mass spectrometry (GC-MS), etc.

[0039] 3. Experimental methods: (1) Model establishment and drug administration: SPF-grade BALB / c mice that passed quarantine were randomly divided into three groups of eight mice each: a normal control group (Control), a model group (Model), and a treatment group (0.3 g / 100 g BW·day). After 7 days of acclimatization, the back hair of the mice was shaved to expose a skin area of ​​approximately 2 cm × 2 cm. Except for the normal control group, the mice in the other groups were sensitized by uniformly applying 1% DNCB solution to their back skin every other day for 7 days to establish an AD mouse model. Mice in the normal control group were only treated with an equal volume of the solvent. From day 7, the mice in the treatment group were administered 0.3 g / 100 g BW daily by gavage, while the model and normal control groups were administered an equal volume of physiological saline. The treatment was continued for 4 weeks, during which 0.5% DNCB was intermittently administered to maintain the AD model until the end of the experiment.

[0040] (2) Mouse body weight and skin score: During the experiment, the body weight of mice in each group was measured and recorded regularly. The symptoms of skin erythema, edema, scaling, and crusting on the back of the mice were scored according to the commonly used AD scoring system. The scores were summed to obtain a comprehensive skin inflammation score.

[0041] (3) Measurement of serum inflammation in mice: After the experiment, blood was collected from the orbits of mice. The blood samples were left to stand at room temperature for 30 minutes before being incubated at 4°C and 1500 r·min. -1 Centrifuge for 15 min under the specified conditions, collect the supernatant serum and store at -20 °C. Determine the levels of TNF-α and IL-10 in mouse serum according to the ELISA kit instructions.

[0042] (4) HE staining to observe pathological changes in skin tissue: After euthanizing the mice, skin tissue from the back was dissected and fixed in 4% paraformaldehyde. Following routine dehydration and paraffin embedding, tissue sections were prepared and stained with hematoxylin and eosin (HE). The pathological morphological changes of the skin tissue, including epidermal thickness and inflammatory cell infiltration, were observed under a light microscope. Simultaneously, toluidine blue staining was performed on the skin sections to observe and count the distribution of mast cells.

[0043] (5) Measurement of skin inflammation in mice: Skin tissue was collected from the back of mice, weighed, and then homogenized with an appropriate amount of pre-cooled lysis buffer under ice bath conditions. After centrifugation, the supernatant was collected, and the levels of IL-6 and IL-10 in the skin tissue were determined according to the instructions of the corresponding kit.

[0044] (6) Determination of butyric acid release in mice: Approximately 20 mg of mouse colon contents were homogenized in 800 μL of 0.5% phosphate solution, and 2-ethylbutyric acid (2-ethylbutyric acid) was added as an internal standard to a final concentration of 10 μg / mL. After centrifugation, 200 μL of the supernatant was mixed with an equal volume of n-butanol and vortexed for 30 s. The processed sample was analyzed using gas chromatography-mass spectrometry (GC-MS) to determine the content of short-chain fatty acids, including butyric acid.

[0045] 4. Experimental Results: (1) Compared with the normal control group, the model group mice showed obvious AD-like skin damage such as erythema, thickening, crusting and scaling after DNCB induction; while after drug intervention, the degree of skin damage on the back of the mice was significantly reduced and the skin appearance gradually recovered. Figure 6 A). Skin clinical scoring results showed that the skin score of the model group mice was significantly higher than that of the control group, while the drug-treated group significantly reduced the skin inflammation score of AD mice. Figure 6B). Throughout the experimental period, the trend of weight change in mice across all groups was basically the same, and the intervention in the drug administration group did not have an adverse effect on the weight gain of mice. Figure 6 C).

[0046] (2) Histopathological analysis further confirmed the ameliorative effect of the drug-treated group on AD skin damage. HE staining results showed that the epidermis of the model group mice was significantly thickened, accompanied by a large number of inflammatory cell infiltrations and focal microabscess formation; in contrast, the skin tissue structure of the drug-treated group mice was more intact, the epidermal thickness and the degree of inflammatory cell infiltration were significantly reduced, and the drug-treated group could significantly inhibit abnormal epidermal proliferation ( Figure 6 D). Furthermore, toluidine blue staining results showed a significant decrease in mast cell density after drug intervention (D). Figure 6 E).

[0047] (3) After drug intervention, the skin IL-6 level decreased significantly, and the IL-10 level increased significantly. Figure 7 A, B). The serum inflammatory factor detection results were consistent with the changes in skin tissue. The serum TNF-α level in the model group mice was significantly increased and the IL-10 level was significantly decreased, while the above changes could be effectively reversed after drug administration. Figure 7 C, D).

[0048] (4) The levels of short-chain fatty acids in the colonic contents of mice were detected, and it was found that the levels of butyric acid and total SCFAs in the model group were significantly lower than those in the control group; after drug intervention, the butyric acid content in the colonic contents of mice increased significantly, and the level of total SCFAs also recovered significantly. Figure 7 E, F).

[0049] In summary, this invention provides a drug-loaded Smilax glabra modified starch drug delivery system, its preparation method, and its application. Using fresh Smilax glabra starch as raw material, the starch is debranched using the PUL enzymatic method to expose hydroxyl sites. Under alkaline conditions, it undergoes an esterification reaction with butyric anhydride to generate modified Smilax glabra starch. Employing a "Top-Down" technique, a uniform and stable drug-loaded Smilax glabra modified starch drug delivery system is formed. This system features small particle size, uniform distribution, and system stability, allowing for the formulation of modern dosage forms such as capsules. It masks the pungent odor of butyric acid, improves patient compliance, achieves colonic targeting, and solves the problem of premature absorption of butyrate by the small intestine. It provides butyric acid both endogenously and exogenously. Butyric acid release experiments show that the drug-loaded Smilax glabra modified starch drug delivery system can effectively promote the release of both endogenous and exogenous butyric acid, significantly reducing the clinical dosage, and ultimately achieving effective treatment of atopic dermatitis by alleviating inflammatory responses.

[0050] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention in any form or substance. Any modifications, alterations, and variations made by those skilled in the art without departing from the scope of the present invention using the disclosed technical content are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and variations made to the above embodiments based on the essential technology of the present invention are still within the scope of the present invention.

Claims

1. A drug delivery system using Smilax glabra-modified starch, characterized in that: The drug-carrier-integrated Smilax glabranch modified starch drug delivery system uses fresh Smilax glabranch starch as raw material. The PUL enzymatic debranching method increases the synthesis sites to reduce the clinical dosage of Smilax glabranch starch. Hydroxybutyrylation modification and Top-Down technology are used to form a uniform and stable drug-carrier-integrated Smilax glabranch modified starch drug delivery system. The PUL enzymatic debranching method refers to treating the Smilax glabranch starch solution with PUL enzyme at room temperature. The hydroxybutyrylation modification refers to reacting a 30-50% w / v aqueous solution of debranched Smilax glabranch starch with butyric anhydride under constant temperature conditions. The Top-Down technology includes the steps of initially dispersing butyrylated Smilax glabranch resistant starch with PVP k30 using a high-speed shearing machine, followed by nano-processing using high-pressure homogenization.

2. A method for preparing a drug delivery system using Smilax glabra-modified starch, characterized in that: The preparation method includes the following steps: (1) Weigh out fresh Smilax glabra starch; (2) Dissolve Smilax glabra starch in a 0.2 mol / L acetic acid / sodium acetate buffer solution at pH 5.2 to prepare a 5-15% Smilax glabra starch milk; (3) Heat the above-mentioned Smilax glabra starch milk at 70~95℃ for 0.5 h to gelatinize it; (4) Cool the gelatinized Smilax glabra starch solution to room temperature, add 50~150 ASPU / g PUL enzyme for debranching treatment, and the debranching treatment time is 8~24 h; (5) Immediately after the reaction is complete, raise the temperature to 95℃ to inactivate the enzyme for 0.5 h to terminate the reaction; (6) Place the enzyme-inactivated Smilax glabra starch solution at 4~20℃ and allow it to coagulate for 6~12 h; (7) Wash the sample with distilled water and ethanol and filter it. Dry, crush and pass through a 100-mesh sieve to obtain debranched starch of Smilax glabra. (8) Prepare a suspension by mixing debranched starch from Smilax glabra with water, with a mass concentration (w / v) of 30-50%; (9) Place the debranched starch suspension of Smilax glabra in a constant temperature water bath at 30-40℃, and add NaOH solution while stirring to adjust the pH to 8-9; (10) Add butyric anhydride / ethanol solution with a volume ratio of 1:1 (v / v) to the debranched starch suspension of Smilax glabra. The mass-volume ratio of starch to butyric anhydride is 1:0.5 to 1:1.

8. (11) Place the suspension in a constant temperature water bath at 30-40°C and react for 3-5 h; (12) Terminate the reaction by adding HCl solution while stirring, and adjust the pH of the butyrylation reaction solution to 6.5-7.5; (13) The solution obtained from the reaction was subjected to sedimentation, washing and drying to obtain modified starch from Smilax glabra; (14) Mix the modified starch of Smilax glabra with deionized water to prepare an aqueous solution of modified starch of Smilax glabra with a mass concentration of 3~5% w / v; (15) Gradually add polyvinylpyrrolidone powder with a mass concentration of 0.5~1.0% w / v to the aqueous solution of modified starch from Smilax glabra; (16) Transfer the above mixed solution to a high-speed shearing machine, set the shearing speed to 10,000~13,000 rpm and the shearing time to 3~7 min, so as to achieve the initial dispersion of Smilax glabra modified starch and PVP K30. (17) The initially dispersed solution was transferred to a high-pressure homogenizer and the homogenization pressure was set to 80~120 MPa. The homogenization process was carried out for 8~15 cycles, followed by freeze-drying to complete the preparation of the drug-carrying Smilax glabra modified starch drug delivery system.

3. The drug-carrier-integrated Smilax glabra modified starch drug delivery system prepared by the method of claim 2.

4. The drug delivery system based on Smilax glabra modified starch as described in claim 1 or 3, characterized in that: The drug delivery system using Smilax glabra modified starch has a RS ratio of 38%–65%. In the ¹H-NMR spectrum, characteristic signal peaks are present at 0.90 ppm methyl, 2.31 ppm methylene and 1.55 ppm methylene, with a degree of substitution of 0.12–0.

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5. The drug delivery system based on Smilax glabra modified starch as described in claim 1 or 3, characterized in that: In the FT-IR spectrum of the drug delivery system based on modified starch from Smilax glabra, the drug delivery system showed a concentration at 1739 cm⁻¹. -1 Absorption peaks are present at 15.23°, 17.18° and 23.02° in the XRD diffraction pattern; C-type crystal structure diffraction peaks are present at 15.23°, 17.18° and 23.02°; thermogravimetric analysis results show good thermal stability.

6. The drug-carrying, modified starch-based drug delivery system based on Smilax glabra as described in claim 1 or 3, characterized in that: The drug delivery system using Smilax glabra modified starch has an average particle size of 150–400 nm and a PDI of 0.05–0.

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7. The use of the integrated drug-carrier Smilax glabra modified starch drug delivery system as described in claim 1, 2, 4, 5 or 6 in the preparation of a drug for treating atopic dermatitis.

8. The application according to claim 7, characterized in that: The atopic dermatitis mentioned refers to atopic dermatitis induced by sensitizers, including ovalbumin, DNCB, and / or house dust mites.

9. The application according to claim 7 or 8, characterized in that: The drug delivery system using Smilax glabra modified starch is an oral preparation; preferably, the oral preparation is either a capsule or a tablet.

10. The application according to any one of claims 7-9, characterized in that: The application refers to the integrated drug delivery system made from modified starch of Smilax glabra having at least one of the following uses: (1) It releases butyrate in the colon, regulates the gut microbiota, and increases butyrate levels in the body; (2) Reduce the levels of inflammatory factors TNF-α and IL-6 in serum and skin; (3) Increase the content of anti-inflammatory factor IL-10 in serum and skin.

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