Method for extracting and separating curcumin by in-situ preparation of eutectic solvent from solid matrix

Abstract

The invention discloses a method for extracting and separating curcumin by in-situ preparation of a deep eutectic solvent from a solid matrix, and belongs to the technical field of curcumin extraction. The method comprises the following steps: uniformly mixing turmeric powder containing a hydrogen bond donor active substance with a hydrogen bond acceptor compound, heating, stirring and extracting to obtain a mixed solution; adding a solvent into the mixed solution, dissolving, centrifuging, taking supernate, removing the solvent through rotary evaporation, adding water to separate out curcumin, and finally centrifugally separating the curcumin again. A deep-eutectic solvent is formed in situ with curcumin in a turmeric solid matrix, so that efficient directional extraction of curcumin is completed, and complexity and pollution risks caused by solvent prefabrication and multi-step operation are avoided; during purification, pure water is introduced to adjust the solvent environment, effective separation of curcumin and the eutectic solvent can be promoted, extraction and purification integration is completed, and the product purity and process greenness integration level is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of curcumin extraction, and particularly relates to a method for in-situ preparation of a low eutectic solvent for extracting and separating curcumin from a solid matrix. BACKGROUND

[0002] Curcuma longa L, also known as Yujin and Baodingxiang, is a perennial herbaceous plant belonging to the Zingiberaceae family. The rhizome of Curcuma longa L is rich in active ingredients such as curcumin and is known as the "natural golden medicine warehouse". A variety of medicinal active substances have been identified in the rhizome of Curcuma longa L, mainly including curcumin compounds (such as curcumin, demethoxycurcumin, and bisdemethoxycurcumin), volatile oil (containing turmerone and ar-turmerone), curcumin polysaccharide, and trace elements. Among them, curcumin is a polyphenol compound with a diarylheptan skeleton, and its content in the rhizome of Curcuma longa L is about 2-5%. In addition to strong antioxidant and anti-inflammatory properties, curcumin exhibits the effects of regulating blood glucose and improving insulin sensitivity in metabolic diseases, and has activities such as anti-atherosclerosis and inhibition of platelet aggregation on the cardiovascular system. It also shows the potential to inhibit tumor cell proliferation and induce cancer cell apoptosis. Recent studies have shown that curcumin can cross the blood-brain barrier and exhibit significant neuroprotective effects in neurological diseases such as Alzheimer's disease and Parkinson's disease. However, the content of curcumin in natural Curcuma longa L is low, and if it is directly ingested, a large amount of raw material is needed to reach the effective treatment concentration, which limits its clinical application. Therefore, developing an efficient extraction process to improve the yield of curcumin is a key prerequisite and research focus for improving its bioavailability and pharmacological effects.

[0003] In the existing research, the traditional solvent reflux method is commonly used for extraction. Huai et al. used reflux method to extract curcumin from turmeric, and through single factor experiment and orthogonal experiment, the optimal extraction conditions were determined as follows: using 95% ethanol as the solvent, solid-liquid ratio 1:12, reflux temperature 80℃, reflux time 60 min, extraction times 2 times, and curcumin content 9.34 mg / g (Journal of Anshan Normal University, 2015(6):43-46). This method is mature, but in practical application, there are problems such as large amount of solvent, long extraction time, low extraction efficiency, etc. There are also studies using supercritical CO2 fluid extraction technology, such as Luo et al. used supercritical CO2 fluid extraction method under the conditions of extraction pressure 35 MPa, extraction temperature 40℃, extraction time 3h, CO2 flow rate 30 L / h, and entrainer dosage 1 mL / g, and under the optimal extraction conditions, the curcumin content was 14.317 mg / g (Modern Food Science and Technology, 2010, 26(04):400-405). Although this method can avoid the degradation of components caused by high temperature, the required equipment is expensive, the operating conditions are harsh, the energy consumption is high, and there is a safety hazard of high pressure operation, which affects the feasibility of large-scale industrialization promotion. Based on the principles of green chemistry and the demand for sustainable development, it is urgent to develop new green solvents and extraction methods to realize the safe, efficient and green extraction of curcumin.

[0004] Deep eutectic solvent is a low melting point eutectic system formed by hydrogen bond donors and hydrogen bond acceptors through intermolecular forces. Compared with traditional organic solvents, deep eutectic solvents have the advantages of strong designability, low toxicity, high biodegradability, simple preparation and low cost, and have been widely used in the fields of green chemistry and natural product extraction. In existing research, the application of deep eutectic solvent usually adopts the mode of pre-preparation and then used for dissolution or extraction. For example, Zhou Feibai et al. constructed a polyethylene glycol-choline chloride type deep eutectic solvent by screening hydrogen bond donors and acceptors, and found that the system can significantly improve the solubility of curcumin powder, reaching 110.04 mg / mL (South China University of Technology, 2025-05-06, CN119925268A), which provides a basis for solvent design for subsequent extraction of active ingredients. In the specific extraction practice of Chinese herbal medicine, some studies have tried to use pre-prepared deep eutectic solvents to extract target components, such as Li Jia et al. constructed a citric acid-glucose (molar ratio 1:1) system and added 15% water as an extraction solvent, and extracted at 50°C, 1:100 (g / mL) for 30 min, achieving a curcumin extraction rate of 21.18 mg / g (Tianjin University of Science and Technology, Master's thesis, 2020). This method has certain effect in improving the extraction efficiency, but there are still some technical limitations in practical application, for example: deep eutectic solvents usually have a wide dissolution spectrum and can dissolve many types of compounds in the raw materials, which may lead to complex impurities in the extract and low purity of the target product. In addition, in order to further purify the target components, solid-phase extraction, membrane separation and other post-processing steps are often required, and the process is relatively complex, the overall time is long, and the energy consumption and cost are also high. These factors to some extent limit its wide application in efficient and green extraction process. SUMMARY

[0005] In view of the shortcomings of the prior art, the purpose of the present application is to provide a method for in-situ preparation of deep eutectic solvent from solid matrix for extraction and separation of curcumin, which solves the problems in the prior art.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] A method for in-situ preparation of deep eutectic solvent from solid matrix for extraction and separation of curcumin, comprising the following steps:

[0008] Mixing the curcumin powder containing hydrogen bond donor active substances with hydrogen bond acceptor compounds uniformly, and heating and stirring to extract curcumin from the curcumin powder to obtain a mixed solution;

[0009] Adding a solvent to the mixed solution to dissolve and centrifuge to obtain a supernatant, then removing the solvent by rotary evaporation, adding water to precipitate curcumin, and finally separating curcumin by centrifugation.

[0010] Further, the hydrogen bond donor active substance is curcumin, demethoxycurcumin and bisdemethoxycurcumin.

[0011] Further, the hydrogen bond acceptor compound includes choline chloride, acetylcholine, urea, amide or quaternary ammonium salt compound.

[0012] Further, the quaternary ammonium salt compound includes tetrabutylammonium bromide, tetrabutylammonium chloride, tetramethylammonium chloride, tetramethylammonium bromide, tetrapropylammonium bromide, tetrapropylammonium chloride, tetraethylammonium chloride, tetraethylammonium bromide, tetrapentylammonium bromide or tetrapentylammonium chloride.

[0013] Further, the heating temperature in the extraction process is 90-130 DEG C; the extraction time is 40-80 min.

[0014] Further, the mass ratio of the curcuma powder to the hydrogen bond acceptor compound is 1:(25-45).

[0015] 7. The method according to claim 1, wherein the solvent is ethanol, methanol, ethyl lactate, isopropyl alcohol or alkaline water.

[0016] Further, the volume ratio of the mixed solution to the solvent is 1:(2-20).

[0017] Further, the heating temperature in the extraction process is 110 DEG C; the extraction time is 60 min.

[0018] Further, the mass ratio of the curcuma powder to the hydrogen bond acceptor compound is 1:35.

[0019] Advantages of the present application:

[0020] (1) The present application forms a low eutectic solvent as an extraction medium by combining a hydrogen bond donor active substance and a hydrogen bond acceptor compound, which is a low-toxicity component of natural origin, avoiding environmental pollution and residual risk of traditional organic solvents, and meeting the green chemistry concept.

[0021] (2) The present application forms a low eutectic solvent in situ with curcumin in the curcuma solid matrix, completes efficient directional extraction of curcumin, avoids the complexity and pollution risk brought by pre-prepared solvent and multi-step operation; during purification, the solvent environment can be adjusted by introducing pure water, which can promote effective separation of curcumin and low eutectic solvent, complete the integration of extraction and purification, and improve the product purity and green integration level of the process.

[0022] (3) The eutectic solvent formed in situ in the application does not require high temperature and high pressure conditions, the eutectic solvent system after extraction can realize efficient recovery of curcumin through simple phase separation, and the solvent components can be recycled, further reducing waste emissions and improving process economy. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced as follows. Obviously, for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0024] Figure 1 is a curcumin standard curve;

[0025] Figure 2 is a high performance liquid chromatogram of a curcumin standard;

[0026] Figure 3 is a high performance liquid chromatogram of curcumin extract extracted by TBAC in the application;

[0027] Figure 4 is a comparison diagram of extraction rate and purity of curcumin extracted by TBAC, ethanol and alkaline water in the application;

[0028] Figure 5 is a nuclear magnetic resonance diagram of curcumin standard, TBAC and curcumin extract extracted by TBAC in the application;

[0029] Figure 6 is an antioxidant experiment result diagram of curcumin extracted by TBAC, ethanol and alkaline water in the application;

[0030] Figure 7 is a curcumin extract diagram of curcumin extracted by TBAC, ethanol and alkaline water in the application. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0032] A method for preparing a eutectic solvent in situ from a solid matrix to extract and separate curcumin, comprising the following steps:

[0033] S1, mixing curcumin powder containing a hydrogen bond donor active substance with a hydrogen bond acceptor compound uniformly, and heating and stirring to extract curcumin from the curcumin powder to obtain a mixed solution;

[0034] S2, adding solvent to the mixed solution to dissolve and centrifuging to obtain supernatant, then removing the solvent by rotary evaporation, adding water to precipitate curcumin, and finally separating curcumin by centrifugation.

[0035] In S1, the hydrogen bond donor active substance is curcumin, demethoxycurcumin and bisdemethoxycurcumin.

[0036] The hydrogen bond acceptor compound includes choline chloride, acetylcholine, urea, amide or quaternary ammonium salt compound; the quaternary ammonium salt compound includes tetrabutylammonium bromide (TBAB), tetrabutylammonium chloride (TBAC), tetramethylammonium chloride (TMAC), tetramethylammonium bromide (TMAB), tetrapropylammonium bromide (TPrAB), tetrapropylammonium chloride (TPrAC), tetraethylammonium chloride (TEAC), tetraethylammonium bromide (TEAB), tetrapentylammonium bromide (TPeAB) or tetrapentylammonium chloride (TPeAC).

[0037] In S1, the heating temperature is 90-130℃; the extraction time is 40-80min; and the mass ratio of curcumin powder to hydrogen bond acceptor compound is 1:(25-45).

[0038] In S2, the solvent is ethanol, methanol, ethyl lactate, isopropyl alcohol or alkaline water; and the volume ratio of the mixed solution in S1 to the solvent is 1:(2-20).

[0039] The extraction process of curcumin is described below by Examples 1-15; wherein, the high performance liquid chromatography is used to obtain the high performance liquid chromatogram of curcumin standard ( Figure 2 ) and curcumin extract ( Figure 3 ); taking the peak area of curcumin standard as the reference, the peak area-concentration relationship is fitted: A (peak area)

[0040] =1.8828x-8.0736 Figure 1 , and the above formula is used to calculate the extraction rate of curcumin in Examples 1-15.

[0041] In addition, the curcumin in the examples is from Sichuan Leshan Xinxuixi Agricultural Co., Ltd., and the hydrogen bond donor active substances contained in the curcumin powder mentioned above include curcumin, demethoxycurcumin and bisdemethoxycurcumin.

[0042] Example 1

[0043] Curcuma powder and TBAC were weighed accurately and mixed uniformly at a mass ratio of 1:35, then transferred to a round-bottom flask; the reaction system was placed in a 90°C constant-temperature oil bath, heated and stirred at a stirring rate of 300 r / min, and after the mixture was completely dissolved to form a uniform transparent solution, the condition was maintained for 60 min of continuous extraction. After the extraction was completed, the curcumin content was determined by high performance liquid chromatography (HPLC), and the extraction rate was 17.38 mg / g.

[0044] Example 2

[0045] Curcuma powder and TBAC were weighed accurately and mixed uniformly at a mass ratio of 1:35, then transferred to a round-bottom flask; the reaction system was placed in a 100°C constant-temperature oil bath, heated and stirred at a stirring rate of 300 r / min, and after the mixture was completely dissolved to form a uniform transparent solution, the condition was maintained for 60 min of continuous extraction. After the extraction was completed, the curcumin content was determined by HPLC, and the extraction rate was 19.18 mg / g.

[0046] Example 3

[0047] Curcuma powder and TBAC were weighed accurately and mixed uniformly at a mass ratio of 1:35, then transferred to a round-bottom flask; the reaction system was placed in a 110°C constant-temperature oil bath, heated and stirred at a stirring rate of 300 r / min, and after the mixture was completely dissolved to form a uniform transparent solution, the condition was maintained for 60 min of continuous extraction. After the extraction was completed, the curcumin content was determined by HPLC, and the extraction rate was 20.87 mg / g.

[0048] Example 4

[0049] Curcuma powder and TBAC were weighed accurately and mixed uniformly at a mass ratio of 1:35, then transferred to a round-bottom flask; the reaction system was placed in a 120°C constant-temperature oil bath, heated and stirred at a stirring rate of 300 r / min, and after the mixture was completely dissolved to form a uniform transparent solution, the condition was maintained for 60 min of continuous extraction. After the extraction was completed, the curcumin content was determined by HPLC, and the extraction rate was 18.42 mg / g.

[0050] Example 5

[0051] Curcuma powder and TBAC were weighed accurately and mixed uniformly at a mass ratio of 1:35, then transferred to a round-bottom flask; the reaction system was placed in a 130°C constant-temperature oil bath, heated and stirred at a stirring rate of 300 r / min, and after the mixture was completely dissolved to form a uniform transparent solution, the condition was maintained for 60 min of continuous extraction. After the extraction was completed, the curcumin content was determined by HPLC, and the extraction rate was 17.00 mg / g.

[0052] The extraction rates of curcumin in Examples 1-5 are shown in Table 1:

[0053] Table 1 Extraction rate of curcumin at different extraction temperatures (mg / g)

[0054]

[0055] From the data in Table 1, it can be seen that as the temperature increases, the extraction rate of curcumin first increases, then reaches the maximum extraction rate at 110°C, and then decreases as the temperature increases. This may be because the increase in temperature can reduce the viscosity of the solvent, enhance the molecular diffusion rate, and high temperature can destroy the plant cell wall structure to promote the dissolution of curcumin from the solid matrix. Above the critical temperature, the thermal stability of curcumin decreases, and oxidation or thermal decomposition reactions may occur, resulting in the loss of active ingredients. In addition, high temperature can change the hydrogen bond network of the eutectic solvent, reducing its extraction capacity. Therefore, the condition of 110°C is selected as the optimal extraction temperature.

[0056] Example 6

[0057] The turmeric powder and TBAC were accurately weighed and mixed uniformly at a mass ratio of 1:35, then transferred to a round-bottom flask; the reaction system was placed in a 110°C constant temperature oil bath, and heated and stirred at a stirring rate of 300 r / min. After the mixture was completely dissolved to form a uniform transparent solution, the condition was maintained for continuous extraction for 40 min. After the extraction was completed, the curcumin content was determined by HPLC, and the extraction rate was measured to be 18.46 mg / g.

[0058] Example 7

[0059] The turmeric powder and TBAC were accurately weighed and mixed uniformly at a mass ratio of 1:35, then transferred to a round-bottom flask; the reaction system was placed in a 110°C constant temperature oil bath, and heated and stirred at a stirring rate of 300 r / min. After the mixture was completely dissolved to form a uniform transparent solution, the condition was maintained for continuous extraction for 50 min. After the extraction was completed, the curcumin content was determined by HPLC, and the extraction rate was measured to be 18.86 mg / g.

[0060] Example 8

[0061] The turmeric powder and TBAC were accurately weighed and mixed uniformly at a mass ratio of 1:35, then transferred to a round-bottom flask; the reaction system was placed in a 110°C constant temperature oil bath, and heated and stirred at a stirring rate of 300 r / min. After the mixture was completely dissolved to form a uniform transparent solution, the condition was maintained for continuous extraction for 60 min. After the extraction was completed, the curcumin content was determined by HPLC, and the extraction rate was measured to be 20.87 mg / g.

[0062] Example 9

[0063] Curcuma powder and TBAC were weighed accurately and mixed uniformly at a mass ratio of 1:35, then transferred to a round-bottom flask; the reaction system was placed in a 110°C constant temperature oil bath, heated and stirred at a stirring rate of 300 r / min, after the mixture was completely dissolved to form a uniform transparent solution, the condition was maintained for 70 min. After the extraction was completed, the curcumin content was determined by HPLC, and the extraction rate was 18.33 mg / g.

[0064] Example 10

[0065] Curcuma powder and TBAC were weighed accurately and mixed uniformly at a mass ratio of 1:35, then transferred to a round-bottom flask; the reaction system was placed in a 110°C constant temperature oil bath, heated and stirred at a stirring rate of 300 r / min, after the mixture was completely dissolved to form a uniform transparent solution, the condition was maintained for 80 min. After the extraction was completed, the curcumin content was determined by HPLC, and the extraction rate was 17.30 mg / g.

[0066] The extraction rates of curcumin in Examples 6-10 are shown in Table 2:

[0067] Table 2 Extraction rate of curcumin (mg / g) under different extraction times

[0068]

[0069] Comparing the data in Table 2, it can be seen that with the increase of extraction time, the extraction rate of curcumin first increases and then decreases. When the extraction time is 60 min, the yield of curcumin is the highest, and with the continuous increase of extraction time, the yield of curcumin decreases. This is because prolonging the extraction time can increase the contact time of the solvent and the matrix, promote the mass transfer balance, and fully release curcumin. However, too long time may cause slow degradation of the dissolved curcumin at high temperature, or the change of system concentration caused by solvent volatilization, reducing the extraction efficiency. Therefore, according to the experimental results, when the extraction time is 60 min, the extraction rate of curcumin reaches the maximum.

[0070] Example 11

[0071] Curcuma powder and TBAC were weighed accurately and mixed uniformly at a mass ratio of 1:35, then transferred to a round-bottom flask; the reaction system was placed in a 110°C constant temperature oil bath, heated and stirred at a stirring rate of 300 r / min, after the mixture was completely dissolved to form a uniform transparent solution, the condition was maintained for 70 min. After the extraction was completed, the curcumin content was determined by HPLC, and the extraction rate was 18.33 mg / g.

[0072] Example 12

[0073] Curcuma powder and TBAC were weighed accurately and mixed uniformly at a mass ratio of 1:30, then transferred to a round-bottom flask; the reaction system was placed in a 110°C constant temperature oil bath, heated and stirred at a stirring rate of 300 r / min, after the mixture was completely dissolved to form a uniform transparent solution, the condition was maintained for 60 min of continuous extraction. After the extraction was completed, the curcumin content was determined by HPLC, and the extraction rate was 17.45 mg / g.

[0074] Example 13

[0075] Curcuma powder and TBAC were weighed accurately and mixed uniformly at a mass ratio of 1:35, then transferred to a round-bottom flask; the reaction system was placed in a 110°C constant temperature oil bath, heated and stirred at a stirring rate of 300 r / min, after the mixture was completely dissolved to form a uniform transparent solution, the condition was maintained for 60 min of continuous extraction. After the extraction was completed, the curcumin content was determined by HPLC, and the extraction rate was 20.87 mg / g.

[0076] Example 14

[0077] Curcuma powder and TBAC were weighed accurately and mixed uniformly at a mass ratio of 1:40, then transferred to a round-bottom flask; the reaction system was placed in a 110°C constant temperature oil bath, heated and stirred at a stirring rate of 300 r / min, after the mixture was completely dissolved to form a uniform transparent solution, the condition was maintained for 60 min of continuous extraction. After the extraction was completed, the curcumin content was determined by HPLC, and the extraction rate was 20.65 mg / g.

[0078] Example 15

[0079] Curcuma powder and TBAC were weighed accurately and mixed uniformly at a mass ratio of 1:45, then transferred to a round-bottom flask; the reaction system was placed in a 110°C constant temperature oil bath, heated and stirred at a stirring rate of 300 r / min, after the mixture was completely dissolved to form a uniform transparent solution, the condition was maintained for 60 min of continuous extraction. After the extraction was completed, the curcumin content was determined by HPLC, and the extraction rate was 20.48 mg / g.

[0080] The extraction rates of curcumin in Examples 11-15 are shown in Table 3:

[0081] Table 3 Extraction rate of curcumin (mg / g) under different extraction mass

[0082]

[0083]

[0084] From the data in Table 3, it can be seen that as the ratio of turmeric powder to hydrogen bond acceptor compound increases, the extraction rate of curcumin first increases and then decreases. When the ratio is 1:35, the curcumin yield is the highest, and as the ratio continues to increase, the curcumin yield decreases. This is because increasing the solvent ratio appropriately can improve the solvent permeability, enhance the hydrogen bond interaction with curcumin, and promote dissolution. Excessive solvent can increase the viscosity of the system or dilute the effect, thereby reducing the mass transfer efficiency. In addition, excessive TBAC can competitively bind with other impurities, affecting the selective extraction of curcumin. Therefore, it can be concluded that when the ratio of turmeric powder to hydrogen bond acceptor compound is 1:35, the extraction rate of curcumin reaches a maximum.

[0085] Example 16

[0086] After the extraction is completed, 12 times the volume of anhydrous ethanol is added to Example 13 (mixed solution), and after being fully dissolved, it is filtered to collect the supernatant. The supernatant is removed by rotary evaporation to remove the ethanol solvent, and the residue is dissolved in a suitable amount of ultrapure water, filtered, and the supernatant is collected. The supernatant is recovered by freeze-drying to obtain a quaternary ammonium salt. The precipitate obtained by filtration is dried by freeze-drying to obtain a dry curcumin crude product Figure 4 a), which has a purity of 20.12% by HPLC analysis.

[0087] Example 17

[0088] The turmeric powder and 1% NaOH solution are accurately weighed and mixed uniformly at a mass ratio of 1:35, then transferred to a round-bottom flask; the reaction system is placed in a 100°C constant temperature oil bath, and heated and stirred at a stirring rate of 300 r / min, and the condition is maintained for 60 min of continuous extraction. After the extraction is completed, the curcumin content is measured by HPLC, and the extraction rate is measured to be 7.50 mg / g. By adjusting the pH to neutral, the curcumin crude product Figure 4 b) is precipitated, and the purity is detected to be 5.49%.

[0089] Example 18

[0090] The turmeric powder and 70% ethanol solution are accurately weighed and mixed uniformly at a mass ratio of 1:35, then transferred to a round-bottom flask; the reaction system is placed in a 70°C constant temperature oil bath, and heated and stirred at a stirring rate of 300 r / min, and the condition is maintained for 60 min of continuous extraction. After the extraction is completed, the curcumin content is measured by HPLC, and the extraction rate is measured to be 15.49 mg / g. By rotary evaporation to remove ethanol, and then freeze-drying, the curcumin crude product Figure 4 c) is obtained, and the purity is detected to be 9.86%.

[0091] By comparing the measured data of Example 13, Example 16, Example 17, and Example 18 Figure 5As can be seen, compared with alkaline water and 70% ethanol extraction, the curcumin content extracted using TBAC in situ technology is the highest (20.87 mg / g), and the purity is also significantly improved, being 3.66 times that of alkaline water extraction and 2.04 times that of 70% ethanol extraction. This further proves that TBAC in situ forms a eutectic solvent to achieve efficient extraction and purification of curcumin.

[0092] Example 19

[0093] Accurately weigh curcumin (CUR) standard, TBAC, and curcumin-TBAC, and dissolve them separately in deuterated DMSO for further processing. 1 H NMR analysis, results as follows Figure 6 As shown, Figure 6 (a) in the text is curcumin. 1 H NMR spectrum Figure 6 (b) in the text is TBAC 1 H NMR spectrum Figure 6 (c) in the text refers to the curcumin-TBAC eutectic solvent. 1 The NMR spectrum showed that the chemical shift of the H peak of CUR's -OH peak was 9.68, while the H proton signal of the -OH peak of CUR-TBAC shifted to a lower field to 9.78, i.e., the chemical shift increased by 0.1, indicating that hydrogen bonding occurred between CUR and TBAC.

[0094] Example 20

[0095] Accurately weigh 4 mg each of curcumin samples extracted with vitamin C (Vc), TBAC (Example 16), ethanol (Example 18), and alkaline water (Example 17), and dissolve them in 10 mL of anhydrous ethanol for DPPH and ABTS antioxidant experiments. Prepare a 0.2 mM DPPH stock solution, and simultaneously dilute the sample solutions according to a concentration gradient, setting up three replicates for each concentration. After incubation at room temperature in the dark for 30 min, the absorbance was measured at 517 nm, and the DPPH free radical scavenging rate for each concentration was calculated. Within the concentration range, the highest free radical scavenging rates of the curcumin extracts extracted with TBAC, ethanol, and alkaline water were 94.35%, 91.29%, and 47.97%, respectively. Figure 7 As shown in (a) of the diagram. ABTS working solution was prepared, and the sample solution was diluted according to a concentration gradient, with three replicates for each concentration. The 96-well plate was incubated at room temperature in the dark for 10 min, and the absorbance was measured at 734 nm. The ABTS free radical scavenging rate for each concentration was calculated. Within the concentration range, the highest free radical scavenging rates of curcumin extracts extracted with TBAC, ethanol, and alkaline water were 92.43%, 88.57%, and 56.78%, respectively. Figure 7 As shown in (b) of the diagram.

[0096] Precise weighing Vc and TBAC, ethanol, alkaline water extraction of curcumin sample 3 mg, and respectively with 30 mL 40% DMSO solution for hydroxyl radical scavenging test. Preparation of 0.75 mmol / L of phenanthroline ferrous ion working solution and 0.03% hydrogen peroxide working solution, while the sample solution is diluted according to the concentration gradient, each concentration sets 3 duplicate wells, 37℃ incubation for 60 min, at 536 nm for absorbance determination, calculate the hydroxyl radical scavenging rate of each concentration. In the concentration range, the highest radical scavenging rate of TBAC, ethanol and alkaline water extracted curcumin extract is 100.00%, 47.26%, 21.28%, respectively, as shown in (c) of Figure 7 .

[0097] The corresponding experimental results in this embodiment show that the antioxidant activity of curcumin obtained by different extraction methods has significant difference, and the activity performance is: TBAC extracted curcumin>70% ethanol extracted curcumin>alkaline water extracted curcumin. Further confirmed that the TBAC in situ extraction technology can not only efficiently extract and purify curcumin, but also better maintain its biological activity, and has potential application value in the field of functional food, health care products or medicine.

[0098] In the description of the present specification, the description of the terms "one embodiment", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0099] The basic principles, main features and advantages of the present application are shown and described above. It should be understood by those skilled in the art that the present application is not limited by the above embodiments, and the above embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application.

Claims

1. A method for in-situ preparation and separation of curcumin from a solid matrix using eutectic solvent extraction, characterized in that, Includes the following steps; Curcumin was extracted from the turmeric powder containing hydrogen bond donor active substances by mixing it evenly with hydrogen bond acceptor compounds and heating and stirring to obtain a mixed solution. The supernatant was obtained by adding solvent to the mixed solution and centrifuging. The solvent was then removed by rotary evaporation, water was added to precipitate curcumin, and finally curcumin was separated by centrifugation again.

2. The method for in-situ preparation and separation of curcumin from a solid matrix using eutectic solvent extraction according to claim 1, characterized in that, The hydrogen bond donor active substances are curcumin, demethoxycurcumin, and bisdemethoxycurcumin.

3. The method for in-situ preparation and separation of curcumin from a solid matrix using eutectic solvent extraction according to claim 1, characterized in that, The hydrogen bond acceptor compounds include: choline chloride, acetylcholine, urea, amides, or quaternary ammonium salts.

4. The method for in-situ preparation and separation of curcumin from a solid matrix using eutectic solvent extraction according to claim 3, characterized in that, The quaternary ammonium salt compounds include: tetrabutylammonium bromide, tetrabutylammonium chloride, tetramethylammonium chloride, tetramethylammonium bromide, tetrapropylammonium bromide, tetrapropylammonium chloride, tetraethylammonium chloride, tetraethylammonium bromide, tetrapentylammonium bromide, or tetrapentylammonium chloride.

5. The method for in-situ preparation and separation of curcumin from a solid matrix using eutectic solvent extraction according to claim 1, characterized in that, The heating temperature during the extraction process is 90-130℃; the extraction time is 40-80 minutes.

6. The method for in-situ preparation and separation of curcumin from a solid matrix using eutectic solvent extraction according to claim 1, characterized in that, The mass ratio of the turmeric powder to the hydrogen bond acceptor compound is 1:(25-45).

7. The method for in-situ preparation and separation of curcumin from a solid matrix using eutectic solvent extraction according to claim 1, characterized in that, The solvent is ethanol, methanol, ethyl lactate, isopropanol, or alkaline water.

8. A method for in-situ preparation and separation of curcumin from a solid matrix using eutectic solvent extraction according to claim 1 or 7, characterized in that, The volume ratio of the mixed solution to the solvent is 1: (2-20)。 9. The method for in-situ preparation and separation of curcumin from a solid matrix using eutectic solvent extraction according to claim 1, characterized in that, The heating temperature during the extraction process was 110℃; the extraction time was 60 min.

10. The method for in-situ preparation and separation of curcumin from a solid matrix using eutectic solvent extraction according to claim 1, characterized in that, The mass ratio of the turmeric powder to the hydrogen bond acceptor compound is 1:35.

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