Curcumin colon-targeted delivery system based on natural deep eutectic solvent and preparation method of curcumin colon-targeted delivery system

Abstract

The invention discloses a curcumin colon-targeted delivery system of a natural deep eutectic solvent and a preparation method of the curcumin colon-targeted delivery system, the natural deep eutectic solvent is firstly synthesized, curcumin is dissolved in the natural deep eutectic solvent, and then the dissolved system is mixed with a gellan gum solution to prepare the curcumin colon-targeted delivery system. According to the method, a stable and efficient curcumin loading system can be prepared, the hydrogel preparation method is green, safe and suitable for the field of food production, the mechanical property and the microstructure compactness of the hydrogel can be remarkably enhanced, efficient loading and gastrointestinal tract controlled release of the curcumin are achieved, particularly, the best performance is achieved for an NADES (Bet-MA) / GG-Cur system, and the hydrogel has the good application prospect. Wide application prospects are realized in the field of functional foods.

Description

Technical Field

[0001] This invention belongs to the field of functional food and biomaterials technology, specifically relating to a curcumin colon-targeted delivery system based on a natural deep eutectic solvent and its preparation method. Background Technology

[0002] Curcumin (Cur) is a polyphenolic compound extracted from turmeric. It possesses excellent anti-inflammatory, antioxidant, and anticancer biological activities, showing great potential, especially in the prevention and adjuvant treatment of colonic diseases such as colon cancer and inflammatory bowel disease. However, curcumin suffers from poor water solubility, low chemical stability in neutral and alkaline environments of the digestive tract, rapid metabolism in vivo, and low oral bioavailability, which severely limit its widespread application in the food and pharmaceutical fields.

[0003] To improve the bioavailability of curcumin, researchers have developed various delivery systems, such as emulsions, nanoparticles, and hydrogels. Among these, hydrogels are favored due to their three-dimensional network structure, which effectively encapsulates and protects the active substance. Gellan gum (GG), a microbial-derived anionic polysaccharide, possesses excellent gelling properties, biocompatibility, and pH responsiveness, making it an ideal gel matrix material. However, using gellan gum alone to load hydrophobic curcumin leads to difficulties in dispersing and ultimately encapsulating curcumin within the polysaccharide system. To address this issue, existing technologies typically require first dissolving curcumin in organic solvents (such as methanol or ethanol) and then adding amphiphilic surfactants such as proteins for emulsification and encapsulation. For example, patent CN 109820815B, in preparing curcumin hydrogels, first disperses curcumin in a solution of organic matter and water, and then encapsulates it using gellan gum and casein. This method not only poses safety risks due to solvent residues and does not conform to the concept of green processing, but also increases the process flow by adding protein, which can easily introduce allergenic substances such as protein. This will limit the application of the product in functional foods and foods for special medical purposes. In addition, existing curcumin delivery systems also have problems such as high curcumin release rate in the intestine, resulting in low bioavailability in the colon.

[0004] Therefore, developing a green and efficient curcumin composite hydrogel delivery system based on natural deep eutectic solvents and gellan gum is of great significance for promoting the application of curcumin in functional foods and foods for special medical purposes. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a curcumin colon-targeted delivery system based on a natural deep eutectic solvent and its preparation method. The system uses a natural deep eutectic eutectic solvent to dissolve curcumin and then encapsulates it using gellan gum. This addresses the issues of residual organic solvents, low bioavailability of curcumin in the colon, and high requirements for wall materials in existing curcumin delivery systems.

[0006] To address the above problems, this invention first provides a method for preparing a curcumin colon-targeted delivery system based on a natural deep eutectic solvent, comprising the following steps:

[0007] S1. Preparation of natural deep eutectic solvent NADES: Mix hydrogen bond donors and hydrogen bond acceptors, heat and stir until a clear and transparent liquid is formed, cool to 20-30°C, and set aside.

[0008] S2. Preparation of curcumin / NADES solution: Dissolve curcumin in NADES prepared in step S1 under ultrasonic conditions;

[0009] S3. Preparation of gellan gum solution: Disperse gellan gum in deionized water and heat and stir until completely dissolved;

[0010] S4. Preparation of composite hydrogel: The curcumin / NADES solution from step S2 is mixed with the gellan gum solution from step S3. After mixing, the mixture is allowed to stand and cool to obtain the curcumin colon-targeted delivery system.

[0011] In one embodiment of the present invention, the hydrogen bond donor is an organic acid, including at least one selected from malic acid, citric acid, lactic acid, succinic acid, and acetic acid.

[0012] In one embodiment of the present invention, the hydrogen bond acceptor includes at least one of glucose, sugar alcohol, choline, and betaine, preferably sugar alcohol and betaine, and more preferably betaine.

[0013] In one embodiment of the present invention, the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is 1:1 to 1:3, preferably 1:1.

[0014] In one embodiment of the present invention, the heating temperature in step S1 is 80-85°C; preferably 80°C, and the stirring time is 3-3.5h.

[0015] In one embodiment of the present invention, the concentration of curcumin dissolved in NADES in step S2 is 2.8 mg / mL to 3 mg / mL, preferably 2.85 mg / mL.

[0016] In one embodiment of the present invention, the heating temperature for dissolving curcumin in step S2 is 60-65°C, preferably 60°C; and the ultrasonic time is 20-30 min, preferably 30 min.

[0017] In one embodiment of the present invention, the concentration of the gellan gum solution in step S3 is 1.65-1.7%, preferably 1.67%, the heating temperature is 80-85°C, preferably 80°C, and the stirring time is 30-35 min, preferably 30 min.

[0018] In one embodiment of the present invention, the volume ratio of curcumin / NADES solution to gellan gum solution in step S4 is 1:9 to 1:10, preferably 1:9, and the final concentration of gellan gum after mixing is preferably 1.5%, and the final concentration of curcumin is 285 μg / mL.

[0019] The present invention also provides a curcumin colon-targeted delivery system prepared using the above method.

[0020] The present invention also provides the application of the curcumin colon-targeted delivery system in the preparation of functional foods, health products or drug delivery systems, especially the application of controlling the release of active substances in a simulated gastrointestinal environment.

[0021] Beneficial effects:

[0022] 1. This invention uses a natural deep eutectic eutectic solvent to dissolve curcumin and uses gellan gum to embed it to construct a curcumin colon-targeted delivery system. The eutectic solvent can not only dissolve curcumin better, but also improve the hydrogel strength of the gellan gum and curcumin system, so that the system can have good gel properties without adding protein, thereby effectively delaying the release rate of curcumin colon-targeted delivery system in the intestine, so that more curcumin can be released and utilized in the colon.

[0023] 2. Natural Deep Eutectic Solvents (NADES) are eutectic mixtures formed by mixing naturally occurring hydrogen bond donors (HBDs, such as organic acids and sugar alcohols) and hydrogen bond acceptors (HBAs, such as choline and betaine) in a certain proportion. They possess advantages such as being green and non-toxic, biodegradable, and having strong dissolving power. This invention uses NADES as a green solvent for curcumin, completely avoiding the use of traditional organic solvents, ensuring safety and non-toxicity, and meeting the requirements of the food industry.

[0024] 3. This invention uses organic acids as hydrogen bond donors and acceptors to prepare the natural deep eutectic solvent NADES. The introduction of NADES has a synergistic effect with gellan gum, significantly enhancing the mechanical properties (storage modulus increased by up to 20 times) and microstructure density of the hydrogel through strong hydrogen bonding and electrostatic interactions, forming a more uniform three-dimensional network with smaller pores. This dense gel network can effectively delay the release of curcumin in the gastrointestinal environment. Especially in the intestinal stage, the betaine-malic acid NADES / gellan gum gel can achieve slow release of curcumin with the lowest cumulative release rate (about 29.7%), significantly improving the bioavailability of curcumin.

[0025] 4. The composite hydrogel system of the present invention provides a new strategy for loading other hydrophobic bioactive substances, and has great application potential in the fields of functional foods, health products, drug sustained-release carriers and edible packaging films. Attached Figure Description

[0026] Figure 1 Rheological frequency scans (storage modulus G' and loss modulus G”) of different hydrogels.

[0027] Figure 2 This is a diagram showing the water distribution of different hydrogels.

[0028] Figure 3 XRD patterns of different hydrogels.

[0029] Figure 4 Cryo-scanning electron microscopy images of different hydrogels.

[0030] Figure 5 The cumulative release curves of curcumin in simulated gastrointestinal fluid are shown for different hydrogels.

[0031] Wherein, GG represents gellan gum, NADES(Bet-MA) / GG, NADES(MA-Glu) / GG, and NADES(MA-Xyl) / GG represent hydrogel systems composed of gellan gum and deep eutectic solvent without curcumin, respectively, and NADES(Bet-MA) / GG-Cur, NADES(MA-Glu) / GG-Cur, and NADES(MA-Xyl) / GG-Cur represent the hydrogel systems in Examples 1 to 3, respectively. Detailed Implementation

[0032] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0033] Test methods

[0034] Rheological property testing: The rheological properties of the composite hydrogel were evaluated using a rheometer under small-amplitude oscillatory shear conditions. Frequency sweeps (0.1-10Hz) were performed at 25℃ with a strain rate of 0.5% and a gap of 1 mm.

[0035] Moisture distribution determination: Low-field nuclear magnetic resonance (LF-NMR) relaxation analysis was performed using a MesoMR23-060V-1 analyzer equipped with a 0.5T permanent magnet. Key operating parameters were adjusted as follows: echo count (NECH) = 15,000, repetition time (TW) = 9,000 ms. Transverse spin-spin relaxation time (T2) data were acquired using a Carr-Purcell-Meiboom-Gill multi-pulse sequence. Data processing was performed through exponential fitting of decay curves and mathematical inversion using MultiExp Inv analysis software.

[0036] X-ray diffraction (XRD) determination: X-ray diffraction analysis of lyophilized samples was performed using an X-ray diffractometer. A Cu-Kα target was used. As the radiation source, the current is 40mA and the voltage is 40kV. The diffraction angle range is set to 2θ = 5° to 40°, and the scanning speed is 5° / min.

[0037] Cryo-electron microscopy: Cryo-scanning electron microscopy images of the samples were acquired using an SU8000 scanning electron microscope. The samples were first rapidly frozen by immersion in liquid nitrogen ice, then immediately transferred to a vacuum cryogenic preparation chamber for sequential freezing fracture, sublimation (-70°C for 20 minutes), and platinum coating (10 mA for 60 seconds). Finally, the samples were transferred to a scanning electron microscope for imaging at an accelerating voltage of 10.0 kV.

[0038] In vitro simulated digestion: Simulated gastric juice was prepared with 0.7% (v / v) hydrochloric acid and 2 mg / mL sodium chloride, and the pH was adjusted to 2 with 1M sodium hydroxide. Porcine pepsin powder was pre-dissolved in the above solution, with an enzyme activity of 4000 U / mL. The simulated gastric juice consisted of 0.5 mL of simulated digestion solution (5.5 mg / mL CaCl2 and 32.9 mg / mL NaCl) and 1 mL of bile salt solution (53.6 mg / mL). Pancreatin powder was pre-dissolved in the above solution, with an activity of 200 U / mL. At predetermined time points (30 and 60 minutes for simulated gastric digestion; 90, 120, 150, and 180 minutes for intestinal digestion), 750 μL of the digestion dispersion was mixed with 750 μL of anhydrous ethanol. After vortexing, the mixture was centrifuged at 10,000 × g for 20 minutes at 20 °C to extract free curcumin.

[0039] Example 1

[0040] A method for preparing a curcumin colon-targeted delivery system based on a natural deep eutectic solvent includes the following steps:

[0041] S1. Preparation of natural deep eutectic solvent NADES: Malic acid (MA) and betaine (Bet) are mixed in a 1:1 molar ratio and heated and stirred at 80°C for 3 hours until a clear and transparent liquid is formed. The mixture is then cooled to room temperature and set aside for later use.

[0042] S2. Preparation of curcumin / NADES solution: Dissolve curcumin in NADES prepared in step S1 under ultrasonic conditions at 60℃, sonicate for 30 min, and prepare a curcumin stock solution with a concentration of 2.85 mg / mL (dilute 10 times before use).

[0043] S3. Preparation of gellan gum solution: Disperse low acyl gellan gum (GG) in deionized water and heat and stir at 80°C for 30 min until completely dissolved;

[0044] S4. Preparation of composite hydrogel: Mix 1 mL of curcumin / NADES solution diluted 10 times with 9 mL of gellan gel solution from step S3, vortex and mix until the final system has a GG concentration of 1.5% (w / v) and a Cur concentration of 285 μg / mL. Allow to stand and cool to room temperature to obtain the curcumin colon-targeted delivery system, denoted as NADES(Bet-MA) / GG-Cur.

[0045] Example 2

[0046] The difference between Example 2 and Example 1 is that betaine in step (1) is replaced with glucose (Glu).

[0047] The obtained curcumin colon-targeted delivery system is denoted as NADES(MA-Glu) / GG-Cur.

[0048] Example 3

[0049] The difference between Example 3 and Example 1 is that betaine in step (1) is replaced with xylitol (Xyl).

[0050] The obtained curcumin colon-targeted delivery system is denoted as NADES(MA-Xyl) / GG-Cur.

[0051] Comparative Example 1

[0052] The difference between Comparative Example 1 and Example 1 is that pure gellan glue hydrogel was used as a control, defined as GG.

[0053] Comparative Example 2

[0054] The difference between Comparative Example 1 and Example 1 is that step S1 is omitted, NADES in step S2 is replaced with anhydrous ethanol, and then GG-Cur gel is prepared as a control by mixing with gellan gum solution according to step S4.

[0055] Figure 1 Rheological frequency scans of different hydrogels, from Figure 1 As can be seen, deep eutectic solvents can significantly improve the storage modulus and loss modulus of gellan gum, indicating that deep eutectic solvents help improve the gel strength of the gellan gum system.

[0056] Figure 2 Results of water distribution measurements for different hydrogels. From Figure 2 It can be seen that the water distribution in the gellan gel is mainly free water. The relaxation time of free water in the example system shifts to the left, which indicates that the addition of NADES reduces the fluidity of water in the gellan gel. This may be because the tight binding of the gel strength binds more water.

[0057] Figure 3 XRD results for different hydrogels. Figure 3 It can be seen that curcumin has many sharp peaks, indicating that curcumin is in a crystalline state. After being loaded into the gel, the sharp peaks disappear, indicating that curcumin changes from a crystalline to an amorphous form, which will be more conducive to absorption.

[0058] Figure 4 The microstructures of different hydrogels. From Figure 4 It can be seen that the structure of Comparative Example 1 has larger pores and is loose and porous, while the structure of the embodiment is dense and has low porosity. In particular, the density of the NADES(Bet-MA) / GG-Cur system is the most significant. This is because the introduction of NADES improves the mechanical strength of the gellan gum and makes the structure more dense, which is the same as the result of rheology.

[0059] Figure 5The results of in vitro simulated digestion using different hydrogels. From Figure 5 It can be seen that, in the intestinal stage, the curcumin release rate of the control group GG-Cur was as high as 68%. The composite hydrogels of this invention all exhibited sustained-release effects, with the release rates in the following order: NADES(MA-Glu) / GG-Cur (44%) > NADES(MA-Xyl) / GG-Cur (38%) > NADES(Bet-MA) / GG-Cur (29.7%). This indicates that NADES(Bet-MA) / GG-Cur possesses the superior intestinal-targeted controlled-release capability.

[0060] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. A method for preparing a curcumin colon-targeted delivery system based on a natural deep eutectic solvent, characterized in that, Includes the following steps: S1. Preparation of natural deep eutectic solvent NADES: Mix hydrogen bond donor and hydrogen bond acceptor, heat and stir until a clear and transparent liquid is formed, cool to 20-30°C, and set aside; wherein, the hydrogen bond donor is an organic acid; S2. Preparation of curcumin / NADES solution: Dissolve curcumin in NADES prepared in step S1 under ultrasonic conditions to obtain curcumin / NADES solution. S3. Preparation of gellan gum solution: Disperse gellan gum in deionized water, heat and stir until completely dissolved to obtain gellan gum solution; S4. Preparation of composite hydrogel: The curcumin / NADES solution from step S2 is mixed with the gellan gum solution obtained in step S3. After mixing, the mixture is allowed to stand and cool to obtain the curcumin colon-targeted delivery system.

2. The preparation method according to claim 1, characterized in that, The hydrogen bond donor includes at least one of malic acid, citric acid, lactic acid, succinic acid, and acetic acid, and the hydrogen bond acceptor includes at least one of glucose, sugar alcohol, choline, and betaine.

3. The preparation method according to claim 1, characterized in that, The molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is 1:1 to 1:

3.

4. The preparation method according to claim 1, characterized in that, The heating temperature in step S1 is 80-85°C, and the stirring time is 3-3.5 hours.

5. The preparation method according to claim 1, characterized in that, In step S2, the concentration of curcumin dissolved in NADES is 2.8 mg / mL-3 mg / mL.

6. The preparation method according to claim 1, characterized in that, In step S2, the curcumin is dissolved under heating conditions of 60-65°C, and the ultrasonication time is 20-30 minutes.

7. The preparation method according to claim 1, characterized in that, The mass percentage of the gellan gum solution in step S3 is 1.65-1.7%, the heating temperature is 80-85℃, and the stirring time is 30-35 min.

8. The preparation method according to claim 1, characterized in that, The volume ratio of curcumin / NADES solution to gellan gum solution in step S4 is 1:9 to 1:

10.

9. A curcumin colon-targeted delivery system prepared by the method according to any one of claims 1 to 8.

10. The use of the curcumin colon-targeted delivery system of claim 9 in the preparation of functional foods, health products or drug delivery systems.

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