Research method for extracting polyphenols and flavonoids compounds in peony flowers by using electrochemically-assisted deep-eutectic solvent

Abstract

The invention belongs to the technical field of natural product extraction, and particularly relates to a research method for extracting polyphenol and flavonoid compounds in peony petals through an electrochemically-assisted eutectic solvent. The invention provides a research method for extracting polyphenols and flavonoids compounds in peony petals by using an electrochemically-assisted deep eutectic solvent, electrochemical wall breaking and DES regulation are combined for the first time by using a solvent design-electrochemical activation-targeted extraction method, phenol oxidation caused by traditional heating is avoided, and meanwhile, the extraction efficiency of the polyphenols and flavonoids compounds in peony petals is improved. The dissolution of target components is selectively enhanced through electrode reaction, the extraction efficiency of bioactive components in the peony petal powder is effectively improved, and the method has the advantages of greenness, high efficiency, short-time consumption reduction and the like, overcomes the defects in the prior art, and has a good application prospect.

Description

1. Technical Field

[0001] The present invention belongs to the technical field of natural product extraction, and specifically relates to a research method for extracting polyphenols and flavonoids from peony flower petals by electrochemically assisted deep eutectic solvents. 2. Background Art

[0002] Peony, belonging to the genus Paeonia of the family Paeoniaceae, is a perennial deciduous shrub with slow growth and a tree age of over a hundred years. It is a precious woody flower native to China. Peony can not only create a good natural and cultural landscape, but also has significant cultural value, medicinal value, edible value, economic benefits and ecological benefits in addition to its important ornamental function. Peony not only has high ornamental value, but also has important medicinal value, being rich in flavonoids, polyphenols, amino acids, proteins, fats, polysaccharides, volatile oils, vitamins, etc. With the development of modern medical science, peony flowers have attracted more and more attention. In recent years, relevant research has been carried out on the extraction methods, analysis and determination methods and antioxidant activities of flavonoids in peony flowers. The phenolic substances and flavonoid compounds contained in peony flowers have significant physiological activities and medicinal values.

[0003] The electrochemically assisted technology can dynamically change the hydrogen bond network of DES by applying an external voltage, enhancing the solubility of polyphenols / flavonoids. Its electroosmotic flow effect can overcome the mass transfer limitation caused by high viscosity. It has been found that the coupling of electrochemistry and DES can achieve efficient extraction at room temperature, avoid thermal damage, and at the same time improve selectivity. At present, the research on electrochemically assisted DES extraction focuses on the fields of metal recovery and synthetic chemistry, and there are almost no reports in the extraction of plant active ingredients. The electrochemically assisted DES extraction technology is expected to break through the bottlenecks of the efficiency and environmental protection of existing plant extraction technologies through multi-scale synergy, provide a new paradigm for the green manufacturing of natural products, and is of great significance in the high-value utilization of peony resources. Therefore, electrochemically assisted deep eutectic solvents are used to extract the bioactive components of peony flower petals, and the extraction efficiency and antioxidant properties of different deep eutectic solvents on flavonoids, phenols and other compounds in peony flower petals are analyzed.

[0004] Pretreatment is a key step in the biomass conversion process, aimed at breaking down naturally recalcitrant structures within the biomass. Pretreatment processes are rapidly evolving, and the development of green pretreatment technologies is crucial for the entire biomass conversion process. Among the numerous pretreatment methods, deep eutectic solvents (DES) are a novel, non-polluting, green solvent. Due to their excellent solubility for biopolymers, they can be used as solvents, cosolvents, or catalysts in biomass conversion or component separation reactions. DES systems have been applied to extract phenolic and flavonoid compounds from biomass, separate lignocellulose components, convert furan derivatives, refine biofuels, and produce nanocellulose. As green biomass pretreatment solvents, they offer advantages such as ease of preparation, high purity, low toxicity, biodegradability, a low melting point, high thermal stability, and low volatility. DES therefore possess the ability to fractionate biomass and demonstrates promising potential for breaking down biomass recalcitrance and disrupting structural crystallinity. As a novel green solvent, DES is currently attracting widespread attention in the pretreatment field. 3. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a research method for extracting polyphenols and flavonoids from peony petals using an electrochemically assisted deep eutectic solvent. The method for extracting bioactive substances from peony flowers provided by the present invention is green and environmentally friendly, short-time and efficient, energy-saving and consumption-reducing, and has a high extraction rate.

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

[0007] One of the technical solutions of the present invention is to provide a research method for extracting polyphenols and flavonoids from peony petals with an electrochemical-assisted deep eutectic solvent, the method comprising the following steps:

[0008] S1.1, mixing peony petal powder with an aqueous deep eutectic solvent, and then performing electrochemical-assisted extraction to obtain an extract;

[0009] S1.2. Centrifuge the extract to obtain a supernatant;

[0010] S1.3. Filter and save the supernatant, and measure the total polyphenol and total flavonoid contents;

[0011] S1.4. Adsorbing the bioactive components of peony flowers using macroporous resin and recovering DES by vacuum distillation;

[0012] Furthermore, the preparation of the aqueous deep eutectic solvent in step S1.1 comprises the following steps:

[0013] S2.1. Stirring the hydrogen bond acceptor and donor to obtain a homogeneous and transparent deep eutectic solvent;

[0014] S2.2. Stir and mix the deep eutectic solvent and water to obtain a water-containing deep eutectic solvent;

[0015] Further, in step S2.1, the hydrogen bond acceptor includes choline chloride and betaine, the hydrogen bond donor includes lactic acid, urea, glucose, and propylene glycol, and the molar ratio of the hydrogen bond acceptor to the donor in step S2.1 is 1:2;

[0016] Further, the water content of the deep eutectic solvent in step S2.2 is 5%;

[0017] Further, the treatment method of peony petals in step S1.1 is as follows: Select the freshly picked petals, remove the parts other than the petals and the spoiled petals, put them in an oven and dry at 40°C, then perform a pulverization treatment after drying, screen the pulverized sample through a 60-mesh sieve, and store it in a sealed bag for dry and light-proof preservation;

[0018] Further, in step S1.1, the temperature of the electrochemically assisted extraction is 25°C, the voltage is 2V, and the reaction time is 30 min;

[0019] Further, the stirring temperature in step S2.1 is 80°C;

[0020] Further, in step S1.2, the extract is precipitated with 70% ethanol to remove DES, the centrifugation speed is 4000 r / min, the time is 10 min, and the supernatant is filtered through a 0.45-μm organic filter membrane;

[0021] Further, in step S1.1, the dosage ratio of the peony flower petal powder to the water-containing deep eutectic solvent is 0.5 g: 20 ml, and the stirring and mixing time is 15 min;

[0022] Further, the specific operation of the electrochemically assisted in step S1.1 is as follows: Select a Ta2O5 electrode as the anode and a Pt electrode as the cathode for the electrode reaction. At 25°C, react for 30 min in the constant current mode, and perform kinetic monitoring by HPLC;

[0023] Further, the specific method for HPLC quantitative analysis is as follows: Use a high-performance chromatograph to perform column analysis on the supernatant. Use a C18 chromatographic column (4.6×250 mm, 5 μm), perform gradient elution with 0.1% formic acid water-acetonitrile as the mobile phase, and use a DAD detector to detect the total phenol content and total flavonoid content in the peony petal extract at wavelengths of 280 nm and 360 nm respectively to improve the detection accuracy.

[0024] Further, the effect of the solid-liquid ratio was investigated: The mass ratios of the peony flower petal powder to the deep eutectic solvent were 1:10, 1:20, 1:30, and 1:40 (w / w), respectively. The peony flower petals were used for the extraction of polyphenols and flavonoids. After the extraction was completed, the supernatant was collected and filtered through a 0.45 μm filter membrane.

[0025] Further, macroporous resin was used to adsorb the target product, and the DES was recovered by vacuum distillation.

[0026] Further, the microstructure of the peony flower petals was characterized: SEM was used to observe the powder morphology before and after electrochemical treatment, and obvious pores were found in the cell wall. FTIR was used to analyze the changes in the cell wall components (cellulose, lignin), and the characteristic peaks of lignin were found to weaken.

[0027] Advantages of the present invention:

[0028] (1) For the first time, the present invention combines electrochemical cell wall breaking with DES regulation, and selectively enhances the dissolution of target components through electrode reactions, effectively improving the extraction efficiency of bioactive components in peony flower petal powder. Compared with traditional methods, the extraction rate is increased by 40%-50%.

[0029] (2) The operating conditions of the present invention are mild (25-40 °C), reducing thermal damage and effectively retaining biological activity. At the same time, the electrochemical process can complete the extraction in a short time (30 min), which is much faster than traditional leaching (1-2 h), and has the advantages of short time and high efficiency.

[0030] (3) The electrochemical-assisted extraction used in the present invention is carried out at a low voltage of 1-5 V, and the energy consumption is much lower than that of traditional heating reflux and ultrasonic assistance, significantly saving energy and reducing consumption, and being suitable for large-scale production.

[0031] (4) The present invention combines electrochemistry, green solvent chemistry and plant extraction technology, and uses the method of solvent design - electrochemical activation - targeted extraction to extract bioactive substances from peony flower petals, providing a new paradigm for the extraction of natural products. 4. Description of the Drawings

[0032] Figure 1 Process flow chart of the electrochemical-assisted deep eutectic solvent extraction of polyphenols and flavonoids from peonies provided by the embodiments of the present invention;

[0033] Figure 2 Extraction rates of total phenols and total flavonoids under different extraction solvents provided by the embodiments of the present invention;

[0034] Figure 3 Extraction rates of total phenols and total flavonoids under different extraction voltages provided by the embodiments of the present invention;

[0035] Figure 4Total phenol and total flavonoid extraction rates of DES at different solid-liquid ratios provided by the embodiments of the present invention 5. Specific embodiments

[0036] The present invention will be described in detail below with reference to specific embodiments. These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given. However, the scope of protection of the present invention is not limited to the following embodiments.

[0037] Unless otherwise specified, the equipment used in the following embodiments represents conventional equipment in the art; unless otherwise specified, the reagents used represent commercially available products or are prepared by conventional methods in the art. Those not described in detail in the following embodiments can be achieved by conventional experimental means in the art.

[0038] In this embodiment, choline chloride and betaine are both white crystals.

[0039] In this embodiment, the freshly picked petals are selected, the parts other than the petals and the spoiled petals are removed, the selected peony petals are dried, crushed, and screened, and stored in a dry and light-proof environment. The drying equipment in this embodiment uses an oven at 40 °C, the crushing equipment uses a stirrer, and the screening equipment uses a 60-mesh sieve.

[0040] Since the eutectic solvent without water has too high viscosity, it will adhere to the flask, three-neck flask, and centrifuge tube, resulting in large errors. Moreover, the eutectic solvent without water has high viscosity and small flow rate, and has poor contact with the peony petal powder, which is not conducive to extraction. At the same time, adding 5%-10% of water can increase the conductivity and make the electrochemical extraction more thorough. Therefore, 5-10% of water needs to be added to the eutectic solvent before the extraction process.

[0041] Example 6:

[0042] A research method for electrochemically assisted extraction of polyphenols and flavonoids from peony petals using a eutectic solvent, comprising the following steps:

[0043] Put 21.81 g of choline chloride and 28.19 g of lactic acid into a 100 mL beaker, make the molar ratio of the two 1:2, shake well, put in a magnetic stirrer, and place it in a heating magnetic stirrer. Heat and stir in a water bath at 80 °C for 15 min until the solution is transparent. Take out the small beaker to obtain a homogeneous and transparent choline chloride-lactic acid eutectic solvent. Add 5-10% of water to the choline chloride-lactic acid eutectic solvent, stir with a glass rod for 1 min, and the transparent floc disappears and completely dissolves (no stratification). Place it in a light-proof place for use;

[0044] Dry the peony petals in an oven, and pass the crushed peony petals through a 60-mesh sieve for light-proof storage;

[0045] Weigh 0.5 g of peony flower petal powder into a conical flask, add 20 mL of choline chloride-lactic acid deep eutectic solvent containing water (solid-liquid ratio 1:20), stir with a glass rod for 1 min until fully mixed, and under the conditions of 25 °C and 2 V voltage, perform electrochemically assisted extraction for 30 min. Then centrifuge at 4000 r / min for 10 min, and pass the supernatant through a 0.45 μm organic filter membrane to obtain the peony flower petal powder solution.

[0046] An electrochemically assisted extraction method for polyphenols and flavonoids in peony flower petals, comprising the following steps:

[0047] Select a Ta2O5-coated electrode as the anode and a platinum plate electrode as the cathode. Before use, ultrasonically clean them successively with acetone, ethanol, and deionized water. The distance between them is 1 cm. Add a diaphragm to separate the two electrodes. Under a 25 °C constant temperature water bath circulation system, stir with a 4000 rpm magnetic stirrer, and set the voltage gradient: 1.0 V, 1.5 V, 2.0 V, 2.5 V, 3.0 V;

[0048] Determine the electrochemical window according to the Butler-Volmer equation and investigate the electrochemical stability of the DES system

[0049]

[0050] In the formula:

[0051] i: net current density of the electrode reaction (A / m 2 );

[0052] i 0: Exchange current density, characterizing the intrinsic kinetic activity of the electrode reaction (the higher the activity, the larger);

[0053] ɑ: transfer coefficient (in the anode and cathode directions), reflecting the symmetry of the reaction energy barrier;

[0054] F: Faraday constant (96,485 C / mol)

[0055] R: gas constant (8.314 J / (mol·K)).

[0056] T: absolute temperature (K).

[0057] A measurement method for electrochemically assisted extraction of polyphenol content in peony flower petals, comprising the following steps:

[0058] Precisely pipette 0.2 ml of the extract (diluted 10 times) and deionized water into a 20 ml graduated test tube;

[0059] To the above test tube, add 15.8 ml of deionized water, then add 1 ml of Folin-Ciocalteu reagent, and shake the test tube thoroughly;

[0060] After 5 minutes, add 3 ml of 20% sodium carbonate solution, shake well, and react for 2 h under light avoidance; measure the absorbance at a wavelength of 765 nm. The total polyphenols are expressed as milligrams of gallic acid equivalents per gram of dry sample (mg GAE / gDW).

[0061] Standard curve plotting: Dissolve 0.5 g of gallic acid in 10 ml of ethanol, and then dilute it to 100 ml with water. Respectively pipette 1, 2, 3, 5, 7, and 10 ml into 100-ml volumetric flasks, and make up to 100 ml with water to create standard solutions with concentrations of 50, 100, 150, 250, 350, and 500 mg / l respectively.

[0062] Finally, measure the absorbance of each concentration of gallic acid standard solution according to the Folin-Ciocalteu method and plot the standard curve.

[0063] A measurement method for the polyphenol content in peony flower petals by electrochemically assisted deep eutectic solvent extraction includes the following steps:

[0064] Add 1 ml of the extract or rutin standard or blank sample (deionized water) to a 10-ml test tube, add deionized water to 5 ml, and add 0.3 ml of 5% NaNO2 solution.

[0065] Let it stand for 6 minutes, add 0.3 ml of 10% AlCl3 solution, let it stand for 6 minutes, add 2 ml of 1 mol / L sodium hydroxide solution, and make up to 10 ml with deionized water.

[0066] After standing for 15 minutes, measure the absorbance at 510 nm. Using rutin as the standard, prepare a standard curve, and the results are expressed as the total flavonoid content in mg RE / g of rutin equivalents per gram of dry matter.

[0067] Standard curve plotting: Take 0.5 g of rutin standard, dissolve it with 60% ethanol and add it to a 100-ml volumetric flask, make up to 100 ml, respectively pipette 0.4, 0.8, 1.2, 2, 3, 4 into 100-ml volumetric flasks, and make up to 100 ml to prepare standard solutions of 20, 40, 60, 100, 150, 200 mg / l.

[0068] Measure the absorbance of each concentration of rutin standard solution according to the NaNO2-AlCl3-NaOH method and plot the standard curve.

[0069] The supernatant was analyzed by high-performance chromatography using a C18 chromatographic column (4.6×250 mm, 5 μm), and gradient elution was performed with 0.1% formic acid in water - acetonitrile as the mobile phase. The total phenolic content and total flavonoid content in the peony petal extract were detected at 280 nm and 360 nm wavelengths by a DAD detector respectively, improving the accuracy of detection.

[0070] An extraction method for polyphenols and flavonoids from peony flower petals assisted by electrochemistry with eutectic solvents, and microstructure characterization, comprising the following steps:

[0071] SEM characterization was used to observe the powder morphology before and after electrochemical treatment, and obvious holes were found in the cell wall. FTIR characterization was used to analyze the changes in cell wall components (cellulose, lignin), and the characteristic peak of lignin was found to weaken.

[0072] Examples 1 to 4 and Comparative Example 1:

[0073] A method for extracting polyphenols and flavonoids from peony flower petals with a solvent and its application, which is basically the same as Example 1, except that the extraction solvent used is different.

[0074] Table 1 Extraction conditions and results of polyphenols and flavonoids from peony flower petals with different extraction solvents

[0075]

[0076]

[0077] As Figure 2 shown, compared with the contents of polyphenols and flavonoids extracted from peony flower petals with the common organic reagent ethanol, the contents of polyphenols and flavonoids extracted from peony flower petals with the electrochemically assisted DES reagent are mostly higher than those extracted with ethanol as the solvent. The reasons for the higher extraction efficiency than that of traditional solvent extraction may be as follows:

[0078] (1) The electrode reaction selectively enhances the dissolution of bioactive components, effectively improving the release of bioactive components in the peony flower petal powder.

[0079] (2) Electrochemistry has compatibility, and DES is not easily decomposed at a lower voltage.

[0080] Generally speaking, Examples 1, 2, 3 and 4 achieved the effect of green environmental protection while improving the extraction efficiency. As Figure 2 、 Figure 3 、 Figure 4As shown, we conducted a statistical difference analysis on the data results and found that when the deep eutectic solvent was choline chloride - lactic acid (1:2), the voltage was 2V, and the solid - liquid ratio was 1:20, the effect was significantly different from that of ethanol, with obvious statistical differences. Different combinations of HBD and HBA lead to different interaction forces between the target and DES during the extraction process, thus affecting the solubility of bioactive substances and the ability to dissolve target components. Compared with ethanol solvent, it also shows higher extraction efficiency. And compared with ethanol which has toxicity, high volatility, etc., DES is green and environmentally friendly, and is more suitable for research and utilization in food, medicine, etc.

[0081] The physical properties of DESs are the key factors affecting the capacity of DESs to extract target active substances in natural products, including the strength of hydrogen bonding, the magnitude of polarity, the value of pH, and viscosity. In addition, the voltage of electrochemical extraction, the solid - liquid ratio of the sample and DESs, the extraction time, and the stirring frequency may all affect the extraction effect of target bioactive substances. In this implementation method, DES is prepared by mixing a fixed ratio of hydrogen - bond - donating and hydrogen - bond - accepting substances. The extraction of DES bioactivity is better. Compared with traditional organic solvents, it avoids the toxicity and environmental pollution problems of traditional organic solvents (such as methanol, ethanol, dichloromethane, etc.), as Figure 2 As shown, it can be seen that organic acid - based organic acid compounds (DES - LAC) as the most polar ones have the best results. And because flavonoid compounds are easily soluble in alkaline solvents, the extraction rate of target flavonoids by polyol - based DES and urea - based DES is higher than that of organic acid - based DES, which is consistent with the weak polarity and medium polarity of the target compounds. In this example, compared with ethanol, the deep eutectic solvent choline chloride - lactic acid (1:2) has the highest content of polyphenols and flavonoids in the extract, has a good wide electrochemical window and good recyclability, and the extraction rates are 38.7mg GAE / g for total polyphenols and 22.7mg GAE / g for total flavonoids respectively. Therefore, the deep eutectic solvent choline chloride - lactic acid (1:2) is selected as the best extraction solvent for polyphenols and flavonoids in peony flower petals.

[0082] The electrochemical - assisted technology can dynamically change the hydrogen - bond network of DES by applying an external voltage, enhancing the solubility of polyphenols / flavonoids. Its electroosmotic flow effect can overcome the mass - transfer limitation caused by high viscosity. It is found that the coupling of electrochemistry and DES can achieve efficient extraction at room temperature, avoid thermal damage, and improve selectivity at the same time. In this example, a Ta2O5 - coated electrode is selected as the anode and a platinum - sheet electrode is used as the cathode. Under a 25°C constant - temperature water - bath circulation system, a magnetic stirrer at 3000rpm is used for stirring, and the voltage gradients are set as: 1.0V, 1.5V, 2.0V, 2.5V, 3.0V for electrochemically extracting target active substances, such as Figure 3As shown, it was found that when the voltage was 1.0 - 2.0 V, the extraction rate increased with the increase of voltage. However, when the voltage was 2.0 - 3.0 V, the extraction rate gradually decreased with the increase of voltage. Therefore, at a voltage of 2.0 V, the extraction rates of polyphenols and flavonoids were the highest, and the extraction efficiencies were 37.9 mg GAE / g for total polyphenols and 22.7 mg GAE / g for total flavonoids, respectively. Thus, 2.0 V was used as the optimal extraction voltage of the electrochemical-assisted deep eutectic solvent for the bioactive components of peony flowers.

[0083] The above description of the embodiments is to enable those of ordinary skill in the art to understand and use the invention.

[0084] Obviously, those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, the present invention is not limited to the above embodiments, and all improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A research method for electrochemically assisted extraction of polyphenols and flavonoids from peony flower petals using deep eutectic solvents, characterized in that, The method includes the following steps: S1.1 Mix the peony flower petal powder with the water-containing deep eutectic solvent by first stirring, and then perform electrochemically assisted extraction to obtain an extract; S1.2 Centrifuge the extract to obtain a supernatant; S1.3 Filter and store the supernatant, and measure the total polyphenol and total flavonoid contents; S1.4 Use macroporous resin to adsorb the bioactive components of peony flowers, and recover the DES by vacuum distillation; The preparation of the water-containing deep eutectic solvent in step S1.1 includes the following steps: S2.1 Stir and mix the hydrogen bond acceptor and donor to obtain a homogeneous and transparent deep eutectic solvent; S2.2 Stir and mix the deep eutectic solvent and water to obtain a water-containing deep eutectic solvent; In step S2.1, the hydrogen bond acceptor includes choline chloride and betaine, the hydrogen bond donor includes lactic acid, urea, glucose, and propylene glycol, and the molar ratio of the hydrogen bond acceptor to the donor in step S2.1 is 1:2; In step S2.2, the water content of the deep eutectic solvent is 5%; In step S1.1, the temperature of the electrochemically assisted extraction is 25 °C, the voltage is 2 V, and the time is 30 min; 2. The research method for extracting polyphenols and flavonoids from peony flower petals by electrochemically assisted deep eutectic solvents according to claim 1, wherein In step S2.1, the stirring temperature is 80 °C; 3. A research method for extracting polyphenols and flavonoids from peony flower petals by electrochemically assisted deep eutectic solvents, characterized in that, The peony flower petal powder extract is precipitated with 70% ethanol to remove DES, the centrifugation speed is 4000 r / min, the time is 10 min, and the supernatant is filtered through a 0.45 μm organic filter membrane; 4. A research method for extracting polyphenols and flavonoids from peony flower petals by electrochemically assisted deep eutectic solvents according to claim 1, characterized in that, In step S1.1, the dosage ratio of the peony flower petal powder to the water-containing deep eutectic solvent is 0.5 g: 20 ml, and the stirring and mixing time is 15 min; 5. A research method for extracting polyphenols and flavonoids from peony flower petals by electrochemically assisted deep eutectic solvents, characterized in that, The specific operation of the electrochemically assisted process is as follows: Select a Ta2O5 electrode as the anode and a Pt electrode as the cathode for the electrode reaction. At 25 °C, in the constant current mode, at a voltage of 2.0 V, react for 30 min, and perform kinetic monitoring using HPLC; 6. The research method for extracting polyphenols and flavonoids from peony flower petals by electrochemically assisted deep eutectic solvents according to claim 1, characterized in that, The treatment method of the peony flower petals in step S1.1 is as follows: Select the freshly picked petals, remove the parts other than the petals and the spoiled petals, put them in an oven at 40 °C for drying, and perform crushing treatment after drying. Screen the crushed sample to 60 mesh, and store it in a sealed bag for drying and storing away from light; 7. A research method for the extraction of polyphenols and flavonoids from peony flower petals by electrochemically assisted deep eutectic solvents, characterized in that The specific method for HPLC quantitative analysis is as follows: Use a high-performance chromatograph to perform column analysis on the supernatant. Use a C18 chromatographic column (4.6 × 250 mm, 5 μm), and perform gradient elution with 0.1% formic acid water-acetonitrile as the mobile phase. The DAD detector performs dual-wavelength detection of the total phenol content and total flavonoid content in the peony petal extract at wavelengths of 280 nm and 360 nm respectively to improve the accuracy of detection; 8. A research method for electrochemically assisted extraction of polyphenols and flavonoids from peony flower petals using deep eutectic solvents, characterized in that The microstructure of the peony flower petals was characterized: SEM characterization was used to observe the powder morphology before and after electrochemical treatment, and obvious holes were found in the cell wall. FTIR characterization was used to analyze the changes in the cell wall components (cellulose, lignin), and the characteristic peak of lignin was found to weaken.

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