Preparation process of kudzuvine root active ingredient extraction-protection integrated sustained-release microcapsule

Abstract

The invention discloses a preparation process of a kudzuvine root active ingredient extraction-protection integrated sustained-release microcapsule. Firstly, supercritical carbon dioxide extraction is combined with a macroporous resin adsorption step-by-step extraction technology, effective components are efficiently extracted and enriched from radix puerariae, and damage to the structure of the active components in the extraction process is reduced to the maximum extent. Loading the enriched radix puerariae extracting solution into a sodium alginate-chitosan composite hydrogel microcapsule core, and coating the outer layer of the sodium alginate-chitosan composite hydrogel microcapsule core with sodium alginate to form a compact shell layer, so as to prepare the microcapsule preparation with slow release performance and gastric acid degradation resistance. The microcapsule is stable in a simulated gastric acid environment, the release duration of effective components in an in-vitro release experiment is relatively long, and the active components can be prevented from being damaged by gastric acid and can be slowly released in intestinal tracts.

Description

Technical Field

[0001] This invention relates to the technical field of drug extraction and preparation of pharmaceutical carriers, specifically to a process for preparing sustained-release microcapsules that integrate extraction and protection of kudzu root active ingredients. Background Technology

[0002] Kudzu root is a commonly used medicinal and edible herb, rich in various active ingredients, mainly isoflavones. Modern pharmacological studies have shown that kudzu root extract has effects such as relieving hangovers, protecting the liver, improving cardiovascular function, and anti-oxidation. However, the active ingredients in kudzu root are mostly glycosides and phenolic compounds, which are easily hydrolyzed and degraded in the highly acidic environment of the stomach after oral administration, leading to reduced activity or loss of efficacy. Furthermore, direct administration of kudzu root extract may cause a rapid increase in blood drug concentration due to excessively rapid release, failing to maintain its efficacy. To improve the stability and bioavailability of active ingredients, novel drug delivery technologies have been introduced into the field of traditional Chinese medicine. For example, microencapsulating the active ingredients of traditional Chinese medicine can mask their unpleasant taste, improve stability, prevent drug inactivation in the stomach, reduce gastric irritation, and achieve sustained-release or controlled-release administration. This approach avoids the shortcomings of traditional Chinese medicine preparations, such as slow onset of action and unstable efficacy.

[0003] Traditional methods for extracting kudzu root typically employ processes such as water decoction, alcohol extraction, or alternating water-alcohol extraction. These methods have several drawbacks: high extraction temperatures and long extraction times may cause decomposition or loss of heat-sensitive active ingredients; organic solvent extraction leaves solvent residues, posing safety risks; and extraction efficiency is limited, resulting in low purity of the extract. Existing patent CN116889611A discloses a method for extracting concentrated kudzu root extract, which obtains a high-concentration extract concentrate through alcohol extraction followed by resin adsorption. However, the conditions for alcohol extraction may damage the active ingredients, and the extraction efficiency is also relatively low.

[0004] Despite advancements in extraction and purification technologies, there is currently a lack of integrated solutions combining sustained-release administration with microencapsulation to address the issue of the easy degradation of kudzu root's active ingredients in gastric acid. Active ingredients obtained through traditional extraction are typically formulated directly into tablets or capsules, which may still be rapidly released and partially inactivated after entering the stomach, affecting efficacy. Therefore, a new process is urgently needed that combines efficient extraction with microencapsulation for sustained release, improving extraction rate and purity while protecting the stability of active ingredients in gastric acid and controlling their release rate in vivo.

[0005] In summary, there is an urgent need for a new technical solution that can gently and efficiently extract the active ingredients of kudzu root while maintaining its structure and activity, and can also encapsulate it into a sustained-release formulation using a suitable carrier to protect the active ingredients in the acidic environment of the stomach and prolong the release time, thereby improving the oral efficacy. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide an integrated sustained-release microcapsule preparation process for the extraction and protection of kudzu root's active ingredients. This process organically combines the high efficiency and gentleness of the extraction process with the sustained-release protection during the formulation stage, solving the problems of kudzu root extract being easily degraded by gastric acid and released too quickly during oral administration. It is particularly suitable for the preparation of hangover relief and liver protection drugs or health products.

[0007] The specific technical solution is as follows:

[0008] This invention employs supercritical carbon dioxide fluid extraction and large-pore resin adsorption purification in a stepwise process to obtain high-purity kudzu root active ingredients. The kudzu root active ingredients are then loaded with hydrogel and coated with a shell to form sustained-release microcapsules.

[0009] Furthermore, the specific steps include the following:

[0010] S1: Extraction of kudzu root raw material with low moisture content using supercritical carbon dioxide fluid extraction process to obtain crude kudzu extract A;

[0011] S2: Dissolve the crude kudzu extract A to form crude extract B. After loading crude extract B onto macroporous adsorption resin for adsorption, wash impurities with water and target components with low-concentration alcohol in sequence. Collect the eluent, concentrate and dry it to obtain kudzu enriched extract C.

[0012] S3: The kudzu root enriched extract C is added to sodium alginate solution to prepare a uniform mixture. The mixture is then dripped into calcium chloride crosslinking solution for curing, so that sodium alginate gels to form hydrogel microsphere core D loaded with the kudzu root enriched extract C.

[0013] S4: The hydrogel microsphere core D is placed in a chitosan solution for composite film formation treatment, so that the chitosan and the surface of the sodium alginate microspheres are electrostatically combined to form a composite hydrogel film; then it is immersed in sodium alginate solution and then transferred to calcium chloride crosslinking solution for secondary curing to obtain wet microcapsules E.

[0014] S5: The wet microcapsules E are subjected to low-temperature vacuum freeze-drying to obtain sustained-release microcapsules.

[0015] Furthermore, the supercritical carbon dioxide fluid process described in S1 has the following specific parameters: extraction temperature of 40-50℃, extraction pressure of 30-35MPa, extraction time of 2 hours, carbon dioxide flow rate of 15L / h, separation temperature of 35℃, and separation pressure of 6MPa.

[0016] Furthermore, the macroporous adsorption resin described in S2 includes AB-8 type resin and D101 type resin.

[0017] Furthermore, in step S2, the crude extract B is loaded and adsorbed onto the resin at a flow rate of 2 mL / min.

[0018] Furthermore, in the homogeneous mixture described in S3, the concentration of sodium alginate is controlled at 1.5–2.0 wt%, and the concentration of kudzu root enriched extract C is controlled at 0.3–0.8% w / v.

[0019] Furthermore, the dripping method described in S3 involves dripping the mixture into the calcium chloride crosslinking solution for curing, wherein the dripping method is performed by uniformly dripping the mixture through a needle with an inner diameter of 0.4 mm; the concentration of the calcium chloride crosslinking solution is 0.2 mol / L, the temperature of the crosslinking solution is 25°C, and the curing time is 5–10 minutes.

[0020] Furthermore, the composite film formation process described in S4 takes 15 to 30 minutes.

[0021] Furthermore, the soaking described in S4 lasts for 5 to 10 minutes; the secondary curing described in S4 lasts for 3 minutes.

[0022] Furthermore, the low-temperature vacuum freeze-drying process described in S5 involves quick-freezing at -30°C for 2 hours, followed by drying under vacuum conditions for 24 hours.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) By using supercritical carbon dioxide extraction combined with macroporous resin purification, this invention extracts the active ingredients of kudzu root under lower temperature and anaerobic conditions, avoiding the decomposition of active ingredients caused by prolonged high-temperature heating. The selective adsorption of macroporous resin further reduces the impact of harmful impurities on the active ingredients. Compared with the traditional hot reflux alcohol extraction process, the kudzu root extract obtained by this invention has higher purity of active ingredients.

[0025] (2) The present invention uses sodium alginate-chitosan composite gel as the microcapsule core, supplemented by an outer sodium alginate shell, to form a double barrier. In a strong acid environment, the composite gel shrinks and is difficult to dissolve, while the chitosan membrane and the outer sodium alginate shell provide additional mechanical support and barrier. The acid resistance of the microcapsules of the present invention greatly ensures that the active substances of kudzu root can be successfully absorbed into the intestine, thereby improving its actual bioavailability.

[0026] (3) Due to the adoption of a reasonable structure and optimized encapsulation parameters, the microcapsules of this invention gradually release the active ingredients in the intestinal environment. The release process is stable. Compared with ordinary preparations without sustained-release measures, the release time of the active ingredients can be extended, avoiding large fluctuations in blood drug concentration. Attached Figure Description

[0027] Figure 1This is a flowchart of the integrated extraction and protection process for sustained-release microcapsules of kudzu root active ingredients in this invention.

[0028] Figure 2 This is a standard curve diagram for the determination of total isoflavone content in Experimental Example 1 of the present invention;

[0029] Figure 3 This is the Fourier transform infrared spectrum result of Experiment Example 2 of the present invention;

[0030] Figure 4 This is a comparative trend graph showing the sustained-release effect in artificial gastric fluid tested in Experimental Example 3 of the present invention;

[0031] Figure 5 This is a comparative trend graph showing the sustained-release effect in artificial intestinal fluid tested in Experimental Example 3 of the present invention. Detailed Implementation

[0032] The following embodiments further explain and illustrate the technical solutions of the present invention. It should be specifically noted that each specific embodiment is a concretization and explanation of the technical solution and should not be considered as a limitation on the scope of protection of the present invention. Those skilled in the art still have the right to modify the technical solutions of these embodiments and make equivalent substitutions for some or all of the technical features, and these modifications or substitutions do not change the essence of the corresponding technical solutions, nor do they cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions described in the present invention.

[0033] This invention proposes an integrated process for preparing sustained-release microcapsules by extracting and protecting the active ingredients of kudzu root, as shown in the attached figure. Figure 1 The diagram shows a flowchart of the preparation process of this invention, and the detailed preparation steps are as follows:

[0034] 1. Raw material pretreatment

[0035] Select high-quality dried kudzu root, clean it, slice it and grind it to a certain fineness, preferably ≤60 mesh, to obtain kudzu root powder; dry the kudzu root powder at 50-60℃ until the moisture content is less than 8% for later use.

[0036] 2. Supercritical CO2 extraction

[0037] Pretreated kudzu powder was placed in the extraction vessel of a supercritical extraction device, using CO2 as the extractant. Preferably, 5% by volume of anhydrous ethanol was added as an entrainer to improve the solubility of moderately polar components such as kudzu isoflavones.

[0038] The extraction conditions were as follows: extraction temperature was set at 40–50℃, extraction pressure was set at 30–35 MPa, extraction time was 2 hours, and CO2 flow rate was set at 15 L / h.

[0039] After the above conditions are applied, the extract phase is slowly released into the separator under reduced pressure. The crude extract of kudzu root is collected at a separation temperature of 35°C and a separation pressure of 6 MPa. The crude extract is a brownish-yellow oily substance.

[0040] 3. Enrichment and purification using macroporous resins

[0041] The crude extract was dispersed in an ethanol-water mixed solvent with a volume ratio of 70:30 to prepare solution A. A suitable macroporous adsorption resin for adsorbing total isoflavones from kudzu root was selected, preferably AB-8 (styrene weakly polar macroporous adsorption resin) or D101 type resin (polystyrene nonpolar adsorption resin). The resin was activated and washed with 95% ethanol and deionized water beforehand. After washing, solution A was passed through a column packed with resin at a flow rate of 2 mL / min for adsorption.

[0042] After adsorption, the resin column was first rinsed with deionized water until the effluent was colorless to remove water-soluble impurities. Then, the active ingredients adsorbed on the resin were slowly eluted with 70% ethanol. After elution, the ethanol eluent was collected, and the ethanol was recovered by concentration under reduced pressure to obtain enriched kudzu root active ingredient extract B. After drying, this extract was a brownish-yellow powder, rich in puerarin and other effective ingredients.

[0043] 4. Preparation of key solutions

[0044] Sodium alginate solution and chitosan solution were prepared as microcapsule carrier materials. Sodium alginate solution was prepared by dissolving sodium alginate in deionized water to a mass concentration of 2% and stirring until homogeneous at room temperature. Chitosan solution was prepared by dissolving chitosan in 1% acetic acid aqueous solution to a mass concentration of 1% and stirring until completely dissolved. The pH was then adjusted to 5 for later use.

[0045] 5. Preparation of drug-containing sodium alginate gel core

[0046] Add the extract B obtained in step 3 to the sodium alginate solution to prepare the liquid. Add the extract while stirring to ensure uniform dispersion. Since extract B is a solid powder, it can be dissolved in a small amount of ethanol before being mixed into the sodium alginate solution. Finally, control the concentration of sodium alginate in the liquid to be 1.5-2.0 wt% and the concentration of extract B to be 0.3-0.8% w / v. These values ​​can be further refined according to the drug loading requirements.

[0047] The prepared sodium alginate solution containing the drug was uniformly dripped into a crosslinking bath containing a calcium chloride solution (0.2 mol / L) through a 0.4 mm inner diameter needle. During the dripping process, the calcium chloride solution was kept at 25°C and gently stirred. The dripped sodium alginate reacted with Ca... 2+Rapid cross-linking forms gel spheres, which are then solidified in a calcium chloride solution for 5–10 minutes to form preliminary drug-containing sodium alginate gel core particles. After the addition is complete, the gel core is filtered out and gently rinsed with distilled water to remove residual Ca2+ from the surface. 2+ And ungelled sodium alginate; the resulting beads have a diameter of 0.5-1 mm (wet state) and are pale yellow and translucent.

[0048] 6. Preparation of chitosan composite layer

[0049] The aforementioned gel core particles were immediately transferred to a pre-prepared chitosan solution and slowly stirred and soaked at room temperature for 15–30 minutes. Because chitosan carries a positive charge, it can electrostatically interact with the negatively charged alginate layer on the surface of the gel beads, gradually depositing a chitosan film on its surface. After coating, the microcapsules were filtered out and gently rinsed with a pH 5 acetate buffer to remove unbound chitosan, thus obtaining chitosan-composite sodium alginate gel microparticles.

[0050] 7. Preparation of secondary sodium alginate embedded shell

[0051] The chitosan-encapsulated gel particles were immersed again in a fresh sodium alginate solution for 5–10 minutes, allowing sodium alginate to adsorb and deposit on the outer surface of the chitosan layer, forming the outermost sodium alginate capsule shell. The particles were then immersed in a calcium chloride solution for 3 minutes to further cross-link and stabilize the second layer of sodium alginate. Through this encapsulation process, sodium alginate / chitosan composite microcapsules were obtained. Their structural characteristics are: a core layer consisting of a drug-containing sodium alginate-calcium-chitosan composite gel membrane, with an outer layer of sodium alginate capsule shell. This multi-layered structure improves the mechanical strength and acid resistance of the microcapsules. The hydrogel's drug-carrying system, combined with the protective effect of the chitosan / sodium alginate shell, forms a pH-enzyme dual controlled-release system. This system contracts and protects the contents in gastric acid, and releases the drug upon entering the intestines, triggered by environmental and bacterial enzymes.

[0052] 8. Microcapsule collection and drying

[0053] The prepared wet microcapsules are rinsed with distilled water 3 to 5 times to remove residual crosslinking agents and solutions on the surface, and then dried under low temperature conditions, preferably by freeze drying: the wet microcapsules are placed at -30°C for 2 hours and then dried in a freeze dryer under vacuum conditions for 24 hours to obtain microcapsule powder with good flowability; after freeze drying, the microcapsule particle size shrinks slightly to 0.3 to 0.6 mm and the surface is slightly rough.

[0054] In the above steps, supercritical CO2 extraction combined with macroporous resin enrichment was used to achieve efficient extraction and purification of kudzu active ingredients. Supercritical extraction was carried out at a low temperature and under anaerobic conditions, which preserved the structural activity of heat-sensitive components such as kudzu isoflavones to the greatest extent. Macroporous resin further purified the ingredients and increased the concentration of active ingredients.

[0055] The microcapsules consist of a multi-layered composite structure composed of a sodium alginate capsule shell, chitosan, and a sodium alginate hydrogel core. The sodium alginate-chitosan composite system is a typical polysaccharide-polymer composite system, which forms a stable membrane through electrostatic interactions. This structure improves the mechanical strength of the capsule and prevents it from being damaged by the gastrointestinal motility environment. On the other hand, it endows the capsule with pH-responsive characteristics: under neutral to slightly alkaline conditions, chitosan gradually deprotonates, weakening its interaction with sodium alginate. Under high ionic strength and the action of intestinal flora enzymes, the sodium alginate gel swells and disintegrates, thereby releasing the contents.

[0056] Based on the aforementioned microcapsule structure, the active ingredient is adequately protected and slowly released in the acidic environment of the stomach, while being rapidly released upon reaching the alkaline environment of the small intestine. This is because at low pH, the sodium alginate gel undergoes reversible shrinkage, and the carboxyl groups of sodium alginate are protonated to form an insoluble alginate gel network, hindering the diffusion of the contents. However, at near-neutral pH, chitosan gradually deprotonates, weakening the cross-linking effect, and the carboxyl groups of sodium alginate reionize and are chelated by phosphate ions in the intestinal fluid (Ca). 2+ This process breaks down the gel network, thereby promoting the rapid release of active ingredients. Therefore, microcapsules can resist the damaging effects of the gastric acid environment on active substances, directing them to the small intestine for large-scale release.

[0057] Example 1

[0058] The integrated extraction and protection process for sustained-release microcapsules of kudzu root active ingredients is as follows:

[0059] S1: Take 1000g of dried kudzu root powder (originating from Bozhou, Anhui, with a moisture content of 6%) and place it in the extraction vessel of a supercritical CO2 extraction device. Set the extraction temperature to 40-50℃ and the pressure to 30-35MPa. Add 5% anhydrous ethanol by volume as an entrainer. Turn on the CO2 flow rate to 15L / h and extract the kudzu root powder for 2 hours. After extraction, reduce the pressure to 8MPa and release the extract into the separator. Set the separation temperature to 35℃ and the separation pressure to 6MPa for collection. The obtained crude kudzu root extract is a brownish-yellow oily substance with a weight of 36.5g.

[0060] S2: The crude kudzu extract prepared in S1 was dissolved in 200 mL of 70% ethanol aqueous solution to prepare crude extract A. 100 g of AB-8 macroporous adsorption resin was packed into a column with a height of 30 cm and an inner diameter of 2.5 cm. After activating the resin with 95% ethanol and water in sequence, crude extract A was loaded onto the column at a flow rate of 2 mL / min for adsorption. After loading, impurities were eluted with 500 mL of deionized water, and then the target component was eluted with 500 mL of 70% ethanol. The ethanol eluent was collected, and the ethanol solvent was removed by vacuum distillation. After drying, 21.4 g of brownish-yellow powder of kudzu enriched extract was obtained.

[0061] S3: Dissolve 5.0 g of the kudzu root enriched extract prepared in S2 in 10 mL of 50% ethanol to prepare a homogeneous extract solution. Add this solution to 100 mL of 2% w / v sodium alginate solution and stir to form a homogeneous drug-containing sodium alginate solution. Use a syringe pump to drip the solution through a 0.4 mm needle into 500 mL of 0.2 mol / L CaCl2 solution at a rate of 2 mL / min. Maintain the temperature of the CaCl2 solution at 25℃. Continue to slowly stir and solidify the gel particles in the CaCl2 solution for 5–10 minutes. Filter out the gel particles and rinse twice with deionized water to obtain wet drug-containing gel beads with a diameter range of 0.5–1 mm.

[0062] S4: Immediately transfer the gel beads prepared in S3 into 100 mL of 1% (w / v) chitosan solution (chitosan dissolved in 1% acetic acid, pH adjusted to 5), gently stir and soak for 15-30 minutes for surface coating. After completion, filter out the coated gel beads and gently rinse with acetic acid buffer at pH 5. Then, place them in 100 mL of freshly prepared 1% (w / v) sodium alginate solution and soak for 5-10 minutes to allow sodium alginate to re-adhere to the outer surface of the chitosan layer. Immediately transfer them into 500 mL of 0.1 mol / L CaCl2 solution to solidify for 3 minutes to obtain wet microcapsules.

[0063] S5: The wet microcapsules prepared in S4 were rinsed with distilled water 3 to 5 times, then frozen at -30°C for 2 hours, and then dried in a freeze dryer under vacuum for 24 hours to obtain 4.8g of free-flowing microcapsule powder with a particle size range of 0.3 to 0.6mm, which is the sustained-release microcapsule of kudzu root active ingredients.

[0064] Examples 2-5

[0065] The preparation method of Example 1, under different conditions and with different preparation results are shown in Table 1:

[0066] Table 1. Summary of differences in conditions and preparation results between Examples 2-5 and Example 1

[0067] Distinguishing conditions Example 1 Example 2 Example 3 Example 4 Example 5 S1: Extraction temperature and pressure 45℃ 33MPa 40℃ 30MPa 50℃ 35MPa 42℃ 33MPa 48℃ 33MPa S1: Weight of crude kudzu extract 36.5g 34.8g 38.2g 35.3g 38.0g S2: Type of adsorption resin AB-8 AB-8 AB-8 D101 D101 S2: Weight of Pueraria lobata enriched extract 21.4g 20.2g 23.7g 21.8g 24.1g <![CDATA[S3: Stirring and curing time in CaCl2 solution]]> 8 minutes 5 minutes 10 minutes 6 minutes 9 minutes S4: Stirring and soaking time in chitosan solution 22 minutes 15 minutes 30 minutes 20 minutes 25 minutes S4: Soaking time in sodium alginate solution again 8 minutes 5 minutes 10 minutes 7 minutes 9 minutes S5: Weight of microcapsule dry powder 4.8g 4.2g 5.6g 4.5g 5.0g

[0068] Apart from the differences mentioned above, all other steps and conditions are the same.

[0069] Comparative Example 1

[0070] Following the preparation steps of Example 1, 1000g of kudzu root powder from the same source as in Example 1 was used. The difference was that traditional alcohol extraction was used instead of supercritical CO2 extraction + macroporous resin adsorption extraction. Specifically, 8 times the amount of 70% ethanol was added for reflux extraction for 2 hours. After filtration, the residue was refluxed again with 6 times the amount of 70% ethanol for 1 hour, and the two filtrates were combined. The filtrate was concentrated under reduced pressure to a paste and subjected to resin adsorption under the same conditions. After vacuum drying, 29.6g of kudzu root extract was obtained for subsequent microcapsule preparation. All other steps were the same.

[0071] Comparative Example 2

[0072] The preparation steps are the same as in Example 1, except that step S4 is omitted. In step S5, after rinsing with distilled water 3-5 times, the wet drug-containing sodium alginate gel beads are first immersed in a 5wt% trehalose + 1wt% hydroxypropyl-β-cyclodextrin solution for 2 hours to form a glassy protective layer to inhibit ice crystal damage, before proceeding to the subsequent freeze-drying step. All other steps are the same.

[0073] Comparative Example 3

[0074] The preparation steps are the same as in Example 1, except that the step of immersing the seaweed in sodium alginate solution again in step S4 is omitted, and the process proceeds directly to the subsequent steps. All other steps are the same.

[0075] Experimental Example 1

[0076] Samples were taken from the kudzu root powder used in Example 1, the crude kudzu root extract prepared in S1, the enriched kudzu root extract prepared in S2, and the dry kudzu root extract prepared in Comparative Example 1. The content of the total isoflavones, the most important active ingredient of kudzu root, in the samples was determined by ultraviolet spectrophotometry and compared. The ultraviolet spectrophotometric determination process is as follows: Since puerarin is the most important and predominant component of total kudzu root isoflavones, the standard curve was calibrated using puerarin. 5.0 mg of puerarin standard was accurately weighed, dissolved in 95% ethanol, and diluted to 25 mL to obtain a standard stock solution with a concentration of 200 μg / mL. 0.2, 0.4, 0.6, 0.8, 1.0, and 1.2 mL of the solution were accurately transferred to 10 mL containers, diluted to the mark with 95% ethanol, and the absorbance was measured at 250 nm. A standard curve was plotted with absorbance as the ordinate and the mass concentration of puerarin as the abscissa. The standard curve is shown in the attached figure. Figure 2 The equation of the standard curve is: A = 0.1001c + 0.0078, R0 2 =0.9996, where A is absorbance, c is concentration, and R0 is concentration. 2 The coefficient of determination was used; then an appropriate amount of sample was taken and diluted into a solution, the absorbance was measured, and the total isoflavone content was calculated according to the standard curve. The calculation and comparison results are shown in Table 2.

[0077] Table 2 Comparison of Experimental Results for Example 3

[0078] experimental group Example 1 - Kudzu Root Raw Material Powder Example 1 - Crude Extract of Kudzu Root Example 1 - Kudzu Root Enriched Extract Comparative Example 1 - Pueraria lobata extract Total isoflavone content (%) 7.97 21.39 58.26 18.47

[0079] The results above show that the combined adsorption of supercritical CO2 extraction and macroporous resin can significantly increase the content of the main active ingredients. In contrast, the traditional alcohol extraction method used in Comparative Example 1 has a lower extraction rate. In addition, due to the limitations of its extraction method and the influence of extraction conditions, the active ingredients of kudzu root may be degraded to a certain extent, resulting in a certain decrease in its actual total amount.

[0080] Experimental Example 2

[0081] The kudzu root enrichment extract prepared in S2 of Example 1 was used to prepare a sample for Fourier transform infrared spectroscopy (FTIR). The test method was based on the national standard GB / T 32199-2015: "General Rules for Qualitative Analysis Techniques of Infrared Spectroscopy"; the test results are attached. Figure 3 As shown in the figure, the sample is at 3401 cm⁻¹. -1 2932cm -1 The absorption peak at 1707 cm⁻¹ is for -OH. -1 The absorption peak at 1637 cm⁻¹ is =O. -1 1587cm -1 1523cm -1 1450cm -1 The absorption peak at that point is a characteristic absorption peak of aromatic hydrocarbons, and the position of the characteristic absorption peak is consistent with the characteristic spectrum of flavonoids, mainly puerarin, indicating that the composition of the extract is as expected.

[0082] Experimental Example 3

[0083] The sustained-release microcapsules prepared in Examples 1-5 and Comparative Examples 1-3 were used to prepare samples, and their sustained-release effects in simulated gastric and intestinal fluids in vitro were tested. The artificial gastric and intestinal fluids were prepared according to the provisions of the Chinese Pharmacopoeia, and the specific preparations are as follows:

[0084] Preparation of artificial gastric juice: Take 234 mL of concentrated hydrochloric acid and dilute it to 1000 mL to obtain solution A. Then, take 16.4 mL of solution A and dilute it to 1000 mL to obtain solution B. Take 100 mg of pepsin, dilute it with solution B, and bring the volume to a final concentration of 4 g / L to obtain gastric juice.

[0085] Preparation of artificial intestinal fluid: Weigh 1.36g of potassium dihydrogen phosphate and add it to 100mL of distilled water. Adjust the pH to 6.8 using 0.2mol / L NaOH solution and set aside. Take 1g of trypsin and put it into a 100mL volumetric flask. Dilute to volume with the prepared solution and shake well.

[0086] Sustained-release effect test in simulated gastric fluid: 0.1g of microcapsule sample was placed in 100mL of simulated gastric fluid and reacted at 37℃. 1mL was taken out every hour and diluted to 100mL. The total isoflavone content of kudzu root in the gastric fluid was tested according to the test method in Experiment 1, and the cumulative release was calculated. The cumulative release time was set to seven hours. Note that an equal volume and concentration of simulated gastric fluid was added after each removal. The sustained-release effect test conditions in intestinal fluid were the same as the gastric fluid test, except that simulated gastric fluid was replaced with simulated intestinal fluid. The results of the sustained-release effect test in simulated gastric fluid are shown in Table 3, and the results of the sustained-release effect test in simulated intestinal fluid are shown in Table 4. The comparative trend chart of the sustained-release effect in simulated gastric fluid is attached. Figure 4 As shown in the attached graph, the comparative trend of sustained-release effects in artificial intestinal fluid is as follows. Figure 5 As shown.

[0087] Table 3 Comparison of sustained-release effect results in artificial gastric fluid in Experiment Example 3

[0088] Cumulative release over different times Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 1 hour (%) 9.84 9.93 9.51 10.61 10.49 13.21 23.44 10.07 2 hours (%) 12.77 12.82 11.97 13.21 13.32 16.07 28.61 14.43 3 hours (%) 15.18 15.31 15.02 16.35 16.41 19.12 33.27 18.32 4 hours (%) 18.23 18.56 19.02 19.12 19.34 21.41 36.31 22.45 5 hours (%) 19.44 19.72 19.91 20.33 20.51 22.29 38.45 27.33 6 hours (%) 20.15 20.33 20.43 21.15 21.67 23.41 39.82 29.45 7 hours (%) 20.69 20.81 21.02 21.60 22.02 24.07 40.63 31.12

[0089] Table 4 Comparison of sustained-release effect results in artificial intestinal fluid in Experiment Example 3

[0090] Cumulative release over different times Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 1 hour (%) 28.72 29.06 28.19 30.38 30.19 25.39 37.21 30.49 2 hours (%) 46.18 46.88 45.47 48.35 47.09 43.22 58.35 50.77 3 hours (%) 52.35 53.71 52.19 54.43 54.06 48.61 70.37 58.34 4 hours (%) 58.61 59.42 59.61 61.27 60.98 54.22 78.61 62.75 5 hours (%) 62.33 63.24 63.49 65.19 64.30 58.37 84.27 66.18 6 hours (%) 64.57 65.31 65.57 67.21 66.57 60.73 85.13 68.61 7 hours (%) 65.34 66.43 66.70 68.43 67.39 61.44 86.08 70.03

[0091] Based on the results shown in the charts, in the sustained-release effect test of artificial gastric fluid, all embodiments showed a stable low release level after 4 hours. Furthermore, in the sustained-release effect test of artificial intestinal fluid, after an initial small release, the release gradually stabilized, consistent with the structural design objectives. Comparative Example 1 used a traditional alcohol extraction method, resulting in a lower content of active ingredients in the extracted material and some damage to the original active ingredients. The high impurity content also reduced the cross-linking stability during subsequent microcapsule formation, affecting the subsequent anti-acid and sustained-release effects. Comparative Example 2 did not form a protective shell through cross-linking, allowing the hydrogel to be directly exposed to the drug release environment, thus failing to achieve low release in gastric acid and sustained release in intestinal fluid. Comparative Example 3 only had a single-shell cross-linking protection, which, compared to other embodiments, negatively impacted both anti-acid and sustained-release performance.

Claims

1. A process for preparing sustained-release microcapsules integrating extraction and protection of kudzu root active ingredients, characterized in that, High-purity kudzu root active ingredients were obtained through a stepwise process of supercritical carbon dioxide fluid extraction and large-pore resin adsorption purification. The kudzu root active ingredients were then loaded with hydrogel and coated with a shell to form sustained-release microcapsules.

2. The integrated sustained-release microcapsule preparation process for extraction and protection of kudzu root active ingredients as described in claim 1, characterized in that, Specifically, the steps include the following: S1: Extraction of kudzu root raw material with low moisture content using supercritical carbon dioxide fluid extraction process to obtain crude kudzu extract A; S2: Dissolve the crude kudzu extract A to form crude extract B. After loading crude extract B onto macroporous adsorption resin for adsorption, wash impurities with water and target components with low-concentration alcohol in sequence. Collect the eluent, concentrate and dry it to obtain kudzu enriched extract C. S3: The kudzu root enriched extract C is added to sodium alginate solution to prepare a uniform mixture. The mixture is then dripped into calcium chloride crosslinking solution for curing, so that sodium alginate gels to form hydrogel microsphere core D loaded with the kudzu root enriched extract C. S4: The hydrogel microsphere core D is placed in a chitosan solution for composite film formation treatment, so that the chitosan and the surface of the sodium alginate microspheres are electrostatically combined to form a composite hydrogel film; then it is immersed in sodium alginate solution and then transferred to calcium chloride crosslinking solution for secondary curing to obtain wet microcapsules E. S5: The wet microcapsules E are subjected to low-temperature vacuum freeze-drying to obtain sustained-release microcapsules.

3. The integrated sustained-release microcapsule preparation process for extraction and protection of kudzu root active ingredients as described in claim 2, characterized in that, The supercritical carbon dioxide fluid process described in S1 has the following specific parameters: extraction temperature of 40-50℃, extraction pressure of 30-35MPa, extraction time of 2 hours, carbon dioxide flow rate of 15L / h, separation temperature of 35℃, and separation pressure of 6MPa.

4. The integrated sustained-release microcapsule preparation process for extraction and protection of kudzu root active ingredients as described in claim 2, characterized in that, The macroporous adsorption resins mentioned in S2 include AB-8 type resin and D101 type resin.

5. The integrated sustained-release microcapsule preparation process for extraction and protection of kudzu root active ingredients as described in claim 2, characterized in that, S2 describes the loading and adsorption of crude extract B onto the resin, wherein the flow rate of crude extract B through the resin is 2 mL / min.

6. The integrated sustained-release microcapsule preparation process for extraction and protection of kudzu root active ingredients as described in claim 2, characterized in that, The homogeneous mixture described in S3, wherein the concentration of sodium alginate is controlled at 1.5–2.0 wt%, and the concentration of kudzu root enriched extract C is controlled at 0.3–0.8% w / v.

7. The integrated sustained-release microcapsule preparation process for extraction and protection of kudzu root active ingredients as described in claim 2, characterized in that, The dripping method described in S3 involves dripping the mixture into a calcium chloride crosslinking solution for curing. The dripping method involves uniformly dripping the mixture using a needle with an inner diameter of 0.4 mm. The concentration of the calcium chloride crosslinking solution is 0.2 mol / L, and the temperature of the crosslinking solution is 25°C. The curing time is 5–10 minutes.

8. The integrated sustained-release microcapsule preparation process for extraction and protection of kudzu root active ingredients as described in claim 2, characterized in that, The composite film formation process described in S4 takes 15 to 30 minutes.

9. The integrated sustained-release microcapsule preparation process for extraction and protection of kudzu root active ingredients as described in claim 2, characterized in that, The soaking described in S4 lasts for 5 to 10 minutes; the secondary curing described in S4 lasts for 3 minutes.

10. The integrated sustained-release microcapsule preparation process for extraction and protection of kudzu root active ingredients as described in claim 2, characterized in that, The low-temperature vacuum freeze-drying process described in S5 involves quick-freezing at -30°C for 2 hours, followed by drying under vacuum for 24 hours.

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