Green method for extracting ginkgo flavone from ginkgo

Abstract

The invention relates to the technical field of plant functional components, and provides a green method for extracting ginkgetin from ginkgo biloba, which comprises the following steps: drying and crushing ginkgo biloba leaves to obtain ginkgo biloba leaf dry powder; the method comprises the following steps: mixing dry ginkgo leaf powder with a deep eutectic solvent extracting agent, extracting, and centrifuging to obtain an extracting solution; adsorbing and purifying the extracting solution to obtain a ginkgo flavone eluent; concentrating and drying the ginkgo flavone eluent to obtain a ginkgo flavone product; wherein the deep eutectic solvent extracting agent is prepared from N, N-dimethyl isopropanolamine, propylene glycol monomethyl ether and water. According to the technical scheme, the problem of low yield of ginkgetin in related technologies is solved.

Description

Technical Field

[0001] This invention relates to the field of plant functional component extraction technology, specifically to a green method for extracting ginkgo flavonoids from ginkgo. Background Technology

[0002] Ginkgo flavonoids are a class of polyphenolic active substances unique to Ginkgo plants, mainly including monomeric components such as quercetin, kaempferol, and isorhamnetin. They possess excellent antioxidant, anti-inflammatory, microcirculation-improving, and nerve cell-protective physiological activities, and have irreplaceable application value in clinical medicine, functional health products, high-end cosmetics, and food additives. With the rapid development of the health industry, the market demand for high-purity ginkgo flavonoids has been increasing year by year, driving the iterative upgrading of related extraction technologies. Currently, the traditional industrial extraction technology for ginkgo flavonoids mainly uses organic solvent extraction, supplemented by water extraction and microwave-assisted extraction. Among them, organic solvent extraction commonly uses reagents such as ethanol, acetone, and ethyl acetate. Although it can achieve a certain extraction efficiency, it has many drawbacks in terms of environmental protection: the solvent is easily volatile, forming volatile organic pollutants that pollute the atmosphere; some solvents are toxic and easily remain in the product, affecting product safety; solvent recovery requires multiple distillations, which are energy-intensive and have limited recovery efficiency, increasing the total production cost. While water extraction has the advantage of being a green and pollution-free solvent, the low solubility of ginkgo flavonoids in water due to their moderate polarity leads to low extraction efficiency. Furthermore, the high impurity content in the extract and the cumbersome subsequent separation and purification steps further increase production difficulty and cost. The aforementioned traditional technologies are all unable to meet the current development requirements of the green chemical industry for low pollution, low energy consumption, and high safety.

[0003] To address the challenges of greening traditional extraction technologies, deep eutectic solvents are increasingly being applied in the extraction of ginkgo flavonoids. These solvents are formed by mixing hydrogen bond acceptors such as choline chloride with hydrogen bond donors such as glycerol in a specific molar ratio. Through strong intermolecular hydrogen bonding, they create a deep eutectic mixture, exhibiting significant green characteristics such as simple preparation process, no need for complex purification steps, low toxicity and biodegradability, low vapor pressure with no volatile pollution, and adjustable properties to suit different target products. They effectively overcome the environmental and safety drawbacks of traditional organic solvents and are considered an ideal alternative for extracting ginkgo flavonoids.

[0004] However, existing ginkgo flavonoid extraction technologies based on eutectic solvents suffer from generally low extraction yields due to insufficient optimization of the eutectic solvent system ratio and low matching degree of extraction process parameters. This makes it difficult to meet the efficiency requirements of large-scale industrial production, thus hindering the industrial application of this green extraction technology. Therefore, a green method for extracting ginkgo flavonoids from ginkgo is needed. Summary of the Invention

[0005] This invention proposes a green method for extracting ginkgo flavonoids from ginkgo, which solves the problem of low yield of ginkgo flavonoids in related technologies.

[0006] The technical solution of the present invention is as follows: This invention proposes a green method for extracting ginkgo flavonoids from ginkgo, comprising the following steps: S1. Dry and pulverize the ginkgo leaves to obtain ginkgo leaf powder; S2. Mix the dried ginkgo leaf powder with a deep eutectic solvent extractant, extract, and then centrifuge to obtain the extract; S3. After adsorption and purification of the extract, ginkgo flavonoid eluent is obtained; S4. The ginkgo flavonoid eluent is concentrated and dried to obtain the ginkgo flavonoid product; The deep eutectic solvent extractant includes N,N-dimethylisopropanolamine, propylene glycol methyl ether, and water.

[0007] As a further technical solution, the molar ratio of N,N-dimethylisopropanolamine to propylene glycol methyl ether is 1~2:1.

[0008] As a further technical solution, the preparation method of the deep eutectic solvent extractant includes the following steps: mixing N,N-dimethylisopropanolamine, propylene glycol methyl ether and water until it becomes a transparent liquid to obtain the deep eutectic solvent extractant.

[0009] As a further technical solution, in the deep eutectic solvent extractant, the mass of water is 10% to 30% of the sum of the masses of N,N-dimethylisopropanolamine and propylene glycol methyl ether.

[0010] As a further technical solution, the mixing temperature is 80~90℃.

[0011] As a further technical solution, in step S3, the adsorption purification includes the following steps: after the extract is adsorbed by macroporous adsorption resin I, it is washed with water and then eluted with eluent I. After collecting the eluent, it is adsorbed by macroporous adsorption resin II, washed with water and then eluted with eluent II to obtain ginkgo flavonoid eluent. The macroporous adsorption resin I and macroporous adsorption resin II are each independently one or two of HPD-600 resin and AB-8 resin.

[0012] As a further technical solution, the macroporous adsorption resin I is HPD-600 macroporous adsorption resin; the macroporous adsorption resin II is AB-8 macroporous adsorption resin.

[0013] This invention presents a green method for extracting ginkgo flavonoids from ginkgo leaves. The purification process, employing HPD-600 macroporous adsorption resin followed by AB-8 macroporous adsorption resin, improves the yield and purity of ginkgo flavonoids. HPD-600 macroporous adsorption resin is a moderately polar resin with a large specific surface area and suitable pore size. It has a broad-spectrum adsorption capacity for flavonoids in ginkgo leaf extract, efficiently retaining most of the ginkgo flavonoids in the extract while initially adsorbing some polar impurities, thus playing a role in coarse separation and enrichment of flavonoids and preventing the loss of target components in subsequent steps to ensure yield. AB-8 macroporous adsorption resin, on the other hand, is a weakly polar resin with a more uniform pore size distribution and stronger specific adsorption capacity for ginkgo flavonoids. It can further adsorb flavonoid components and repel residual strongly polar impurities, thereby reducing the loss of target components and lowering the residual proportion of impurities, ultimately improving the yield and purity of ginkgo flavonoids.

[0014] As a further technical solution, the eluent I and eluent II are each independently an aqueous solution of ethanol with a volume fraction of 40% to 60%.

[0015] As a further technical solution, in step S2, the mass-to-volume ratio of the dried ginkgo leaf powder and the deep eutectic solvent extractant is 1g:8~12mL.

[0016] As a further technical solution, in step S2, the extraction temperature is 40~50℃ and the time is 30~60min.

[0017] As a further technical solution, in step S2, the relative centrifugal force is 10000~12000g and the time is 15~25min.

[0018] As a further technical solution, in step S4, the concentration is vacuum concentration and the drying is spray drying.

[0019] The working principle and beneficial effects of this invention are as follows: This invention discloses a green method for extracting ginkgo flavonoids from ginkgo leaves. The method uses a deep eutectic solvent composed of N,N-dimethyl isopropanolamine, propylene glycol methyl ether, and water as the extraction agent, which significantly improves the extraction yield of ginkgo flavonoids. Specifically, the hydroxyl groups in the N,N-dimethyl isopropanolamine molecule can form a dynamic reversible hydrogen bond network with the hydroxyl groups in the propylene glycol methyl ether molecule. This network competes with the polar groups of cellulose and pectin in the ginkgo leaf cell wall for hydrogen bonds, disrupting the original intermolecular hydrogen bond cross-links. This disrupts the intermolecular interactions of cellulose, pectin, and other components in the ginkgo leaf cell wall, promoting cell wall rupture and releasing intracellular ginkgo flavonoids. Simultaneously, the water in the system effectively reduces the viscosity of the deep eutectic solvent, increasing the solvent's penetration rate and mass transfer efficiency in the ginkgo leaf matrix. This allows for more thorough contact between the solvent and ginkgo flavonoids, further promoting the dissolution of ginkgo flavonoids and ultimately improving the extraction yield. This deep eutectic solvent has good recyclability. After extraction, it can be efficiently separated and recovered by vacuum distillation. After simple preparation, it can be reused repeatedly, which can greatly reduce solvent consumption and waste liquid discharge, and has green and environmentally friendly characteristics. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1 A green method for extracting ginkgo flavonoids from ginkgo biloba includes the following steps: S1. Dry and pulverize the ginkgo leaves to obtain ginkgo leaf powder; S2. Mix the dried ginkgo leaf powder with the deep eutectic solvent extractant, extract at 40℃ for 60 min, and then centrifuge at a relative centrifugal force of 10000g for 25 min to obtain the extract; the mass-volume ratio of dried ginkgo leaf powder to deep eutectic solvent extractant is 1g:10mL. S3. After adsorption purification of the extract, the ginkgo flavonoid eluent is obtained. S4. The ginkgo flavonoid eluent is concentrated under reduced pressure and spray-dried to obtain the ginkgo flavonoid product. A method for preparing a deep eutectic solvent extractant includes the following steps: mixing N,N-dimethylisopropanolamine, propylene glycol methyl ether, and water at 80°C until a transparent liquid is obtained, thus yielding a deep eutectic solvent extractant; the molar ratio of N,N-dimethylisopropanolamine to propylene glycol methyl ether is 1:1; the mass of water is 20% of the sum of the masses of N,N-dimethylisopropanolamine and propylene glycol methyl ether. In step S3, adsorption purification includes the following steps: the extract is adsorbed using AB-8 resin, washed with water, and then eluted with a 50% (v / v) ethanol aqueous solution to obtain the ginkgo flavonoid eluent.

[0022] Example 2 A green method for extracting ginkgo flavonoids from ginkgo biloba includes the following steps: S1. Dry and pulverize the ginkgo leaves to obtain ginkgo leaf powder; S2. Mix the dried ginkgo leaf powder with the deep eutectic solvent extractant, extract at 45℃ for 45 min, and then centrifuge at a relative centrifugal force of 11000g for 20 min to obtain the extract; the mass-volume ratio of dried ginkgo leaf powder to deep eutectic solvent extractant is 1g:10mL. S3. After adsorption purification of the extract, the ginkgo flavonoid eluent is obtained. S4. The ginkgo flavonoid eluent is concentrated under reduced pressure and spray-dried to obtain the ginkgo flavonoid product. A method for preparing a deep eutectic solvent extractant includes the following steps: mixing N,N-dimethylisopropanolamine, propylene glycol methyl ether, and water at 85°C until a transparent liquid is formed; the molar ratio of N,N-dimethylisopropanolamine to propylene glycol methyl ether is 1:1; the mass of water is 20% of the sum of the masses of N,N-dimethylisopropanolamine and propylene glycol methyl ether. In step S3, adsorption purification includes the following steps: the extract is adsorbed using AB-8 resin, washed with water, and then eluted with a 50% (v / v) ethanol aqueous solution to obtain the ginkgo flavonoid eluent.

[0023] Example 3 A green method for extracting ginkgo flavonoids from ginkgo biloba includes the following steps: S1. Dry and pulverize the ginkgo leaves to obtain ginkgo leaf powder; S2. Mix the dried ginkgo leaf powder with the deep eutectic solvent extractant, extract at 50℃ for 30 min, and then centrifuge at a relative centrifugal force of 12000g for 15 min to obtain the extract; the mass-volume ratio of dried ginkgo leaf powder to deep eutectic solvent extractant is 1g:10mL. S3. After adsorption purification of the extract, the ginkgo flavonoid eluent is obtained. S4. The ginkgo flavonoid eluent is concentrated under reduced pressure and spray-dried to obtain the ginkgo flavonoid product. A method for preparing a deep eutectic solvent extractant includes the following steps: mixing N,N-dimethylisopropanolamine, propylene glycol methyl ether, and water at 90°C until a transparent liquid is formed; the molar ratio of N,N-dimethylisopropanolamine to propylene glycol methyl ether is 1:1; the mass of water is 20% of the sum of the masses of N,N-dimethylisopropanolamine and propylene glycol methyl ether. In step S3, adsorption purification includes the following steps: the extract is adsorbed using AB-8 resin, washed with water, and then eluted with a 50% (v / v) ethanol aqueous solution to obtain the ginkgo flavonoid eluent.

[0024] Example 4 A green method for extracting ginkgo flavonoids from ginkgo biloba includes the following steps: S1. Dry and pulverize the ginkgo leaves to obtain ginkgo leaf powder; S2. Mix the dried ginkgo leaf powder with the deep eutectic solvent extractant, extract at 40℃ for 60 min, and then centrifuge at a relative centrifugal force of 10000g for 25 min to obtain the extract; the mass-volume ratio of dried ginkgo leaf powder to deep eutectic solvent extractant is 1g:10mL. S3. After adsorption purification of the extract, the ginkgo flavonoid eluent is obtained. S4. The ginkgo flavonoid eluent is concentrated under reduced pressure and spray-dried to obtain the ginkgo flavonoid product. A method for preparing a deep eutectic solvent extractant includes the following steps: mixing N,N-dimethylisopropanolamine, propylene glycol methyl ether, and water at 80°C until a transparent liquid is obtained, thus yielding the deep eutectic solvent extractant; the molar ratio of N,N-dimethylisopropanolamine to propylene glycol methyl ether is 1.5:1; the mass of water is 20% of the sum of the masses of N,N-dimethylisopropanolamine and propylene glycol methyl ether. In step S3, adsorption purification includes the following steps: the extract is adsorbed using AB-8 resin, washed with water, and then eluted with a 50% (v / v) ethanol aqueous solution to obtain the ginkgo flavonoid eluent.

[0025] Example 5 A green method for extracting ginkgo flavonoids from ginkgo biloba includes the following steps: S1. Dry and pulverize the ginkgo leaves to obtain ginkgo leaf powder; S2. Mix the dried ginkgo leaf powder with the deep eutectic solvent extractant, extract at 40℃ for 60 min, and then centrifuge at a relative centrifugal force of 10000g for 25 min to obtain the extract; the mass-volume ratio of dried ginkgo leaf powder to deep eutectic solvent extractant is 1g:10mL. S3. After adsorption purification of the extract, the ginkgo flavonoid eluent is obtained. S4. The ginkgo flavonoid eluent is concentrated under reduced pressure and spray-dried to obtain the ginkgo flavonoid product. A method for preparing a deep eutectic solvent extractant includes the following steps: mixing N,N-dimethylisopropanolamine, propylene glycol methyl ether, and water at 80°C until a transparent liquid is obtained, thus yielding a deep eutectic solvent extractant; the molar ratio of N,N-dimethylisopropanolamine to propylene glycol methyl ether is 2:1; the mass of water is 20% of the sum of the masses of N,N-dimethylisopropanolamine and propylene glycol methyl ether. In step S3, adsorption purification includes the following steps: the extract is adsorbed using AB-8 resin, washed with water, and then eluted with a 50% (v / v) ethanol aqueous solution to obtain the ginkgo flavonoid eluent.

[0026] Example 6 A green method for extracting ginkgo flavonoids from ginkgo biloba includes the following steps: S1. Dry and pulverize the ginkgo leaves to obtain ginkgo leaf powder; S2. Mix the dried ginkgo leaf powder with the deep eutectic solvent extractant, extract at 40℃ for 60 min, and then centrifuge at a relative centrifugal force of 10000g for 25 min to obtain the extract; the mass-volume ratio of dried ginkgo leaf powder to deep eutectic solvent extractant is 1g:10mL. S3. After adsorption purification of the extract, the ginkgo flavonoid eluent is obtained. S4. The ginkgo flavonoid eluent is concentrated under reduced pressure and spray-dried to obtain the ginkgo flavonoid product. A method for preparing a deep eutectic solvent extractant includes the following steps: mixing N,N-dimethylisopropanolamine, propylene glycol methyl ether, and water at 80°C until a transparent liquid is obtained, thus yielding a deep eutectic solvent extractant; the molar ratio of N,N-dimethylisopropanolamine to propylene glycol methyl ether is 1:1; the mass of water is 20% of the sum of the masses of N,N-dimethylisopropanolamine and propylene glycol methyl ether. In step S3, adsorption purification includes the following steps: In step S3, adsorption purification includes the following steps: the extract is adsorbed using HPD-600 resin, washed with water, and then eluted with a 40% (v / v) ethanol aqueous solution to obtain the ginkgo flavonoid eluent.

[0027] Example 7 A green method for extracting ginkgo flavonoids from ginkgo biloba includes the following steps: S1. Dry and pulverize the ginkgo leaves to obtain ginkgo leaf powder; S2. Mix the dried ginkgo leaf powder with the deep eutectic solvent extractant, extract at 40℃ for 60 min, and then centrifuge at a relative centrifugal force of 10000g for 25 min to obtain the extract; the mass-volume ratio of dried ginkgo leaf powder to deep eutectic solvent extractant is 1g:10mL. S3. After adsorption purification of the extract, the ginkgo flavonoid eluent is obtained. S4. The ginkgo flavonoid eluent is concentrated under reduced pressure and spray-dried to obtain the ginkgo flavonoid product. A method for preparing a deep eutectic solvent extractant includes the following steps: mixing N,N-dimethylisopropanolamine, propylene glycol methyl ether, and water at 80°C until a transparent liquid is obtained, thus yielding a deep eutectic solvent extractant; the molar ratio of N,N-dimethylisopropanolamine to propylene glycol methyl ether is 1:1; the mass of water is 20% of the sum of the masses of N,N-dimethylisopropanolamine and propylene glycol methyl ether. In step S3, the adsorption purification includes the following steps: the extract is adsorbed with HPD-600 resin, washed with water, eluted with 40% ethanol aqueous solution, the eluent is collected, and then adsorbed with AB-8 resin, washed with water, and eluted with 50% ethanol aqueous solution to obtain ginkgo flavonoid eluent.

[0028] Example 8 A green method for extracting ginkgo flavonoids from ginkgo biloba includes the following steps: S1. Dry and pulverize the ginkgo leaves to obtain ginkgo leaf powder; S2. Mix the dried ginkgo leaf powder with the deep eutectic solvent extractant, extract at 40℃ for 60 min, and then centrifuge at a relative centrifugal force of 10000g for 25 min to obtain the extract; the mass-volume ratio of dried ginkgo leaf powder to deep eutectic solvent extractant is 1g:10mL. S3. After adsorption purification of the extract, the ginkgo flavonoid eluent is obtained. S4. The ginkgo flavonoid eluent is concentrated under reduced pressure and spray-dried to obtain the ginkgo flavonoid product. A method for preparing a deep eutectic solvent extractant includes the following steps: mixing N,N-dimethylisopropanolamine, propylene glycol methyl ether, and water at 80°C until a transparent liquid is obtained, thus yielding a deep eutectic solvent extractant; the molar ratio of N,N-dimethylisopropanolamine to propylene glycol methyl ether is 1:1; the mass of water is 20% of the sum of the masses of N,N-dimethylisopropanolamine and propylene glycol methyl ether. In step S3, the adsorption purification includes the following steps: after the extract is adsorbed with NKA-9 resin, it is washed with water and then eluted with a 40% (v / v) ethanol aqueous solution. After collecting the eluent, it is adsorbed with AB-8 resin, washed with water, and then eluted with a 50% (v / v) ethanol aqueous solution to obtain the ginkgo flavonoid eluent.

[0029] Example 9 A green method for extracting ginkgo flavonoids from ginkgo biloba includes the following steps: S1. Dry and pulverize the ginkgo leaves to obtain ginkgo leaf powder; S2. Mix the dried ginkgo leaf powder with the deep eutectic solvent extractant, extract at 40℃ for 60 min, and then centrifuge at a relative centrifugal force of 10000g for 25 min to obtain the extract; the mass-volume ratio of dried ginkgo leaf powder to deep eutectic solvent extractant is 1g:10mL. S3. After adsorption purification of the extract, the ginkgo flavonoid eluent is obtained. S4. The ginkgo flavonoid eluent is concentrated under reduced pressure and spray-dried to obtain the ginkgo flavonoid product. A method for preparing a deep eutectic solvent extractant includes the following steps: mixing N,N-dimethylisopropanolamine, propylene glycol methyl ether, and water at 80°C until a transparent liquid is obtained, thus yielding a deep eutectic solvent extractant; the molar ratio of N,N-dimethylisopropanolamine to propylene glycol methyl ether is 1:1; the mass of water is 20% of the sum of the masses of N,N-dimethylisopropanolamine and propylene glycol methyl ether. In step S3, the adsorption purification includes the following steps: after the extract is adsorbed with HPD-600 resin, it is washed with water and then eluted with a 40% (v / v) ethanol aqueous solution. After collecting the eluent, it is adsorbed with D-101 resin, washed with water, and then eluted with a 50% (v / v) ethanol aqueous solution to obtain the ginkgo flavonoid eluent.

[0030] Example 10 A green method for extracting ginkgo flavonoids from ginkgo biloba includes the following steps: S1. Dry and pulverize the ginkgo leaves to obtain ginkgo leaf powder; S2. Mix the dried ginkgo leaf powder with the deep eutectic solvent extractant, extract at 40℃ for 60 min, and then centrifuge at a relative centrifugal force of 10000g for 25 min to obtain the extract; the mass-volume ratio of dried ginkgo leaf powder to deep eutectic solvent extractant is 1g:10mL. S3. After adsorption purification of the extract, the ginkgo flavonoid eluent is obtained. S4. The ginkgo flavonoid eluent is concentrated under reduced pressure and spray-dried to obtain the ginkgo flavonoid product. A method for preparing a deep eutectic solvent extractant includes the following steps: mixing N,N-dimethylisopropanolamine, propylene glycol methyl ether, and water at 80°C until a transparent liquid is obtained, thus yielding a deep eutectic solvent extractant; the molar ratio of N,N-dimethylisopropanolamine to propylene glycol methyl ether is 1:1; the mass of water is 20% of the sum of the masses of N,N-dimethylisopropanolamine and propylene glycol methyl ether. In step S3, the adsorption purification includes the following steps: the extract is adsorbed with AB-8 resin, washed with water, eluted with 40% ethanol aqueous solution, the eluent is collected, and then adsorbed with HPD-600 resin, washed with water, and then eluted with 50% ethanol aqueous solution to obtain ginkgo flavonoid eluent.

[0031] Comparative Example 1 Compared with Example 1, the only difference in this comparative example is that N,N-dimethylisopropanolamine is replaced with an equal amount of propylene glycol methyl ether.

[0032] Comparative Example 2 Compared with Example 1, the only difference in this comparative example is that propylene glycol methyl ether is replaced with an equal amount of N,N-dimethylisopropanolamine.

[0033] The content of ginkgo flavonoids in the ginkgo flavonoid products obtained in the above examples and comparative examples was determined by spectrophotometry, and the yield and purity of ginkgo flavonoids were calculated. The results are shown in Table 1 below. Yield = (mass of ginkgo flavonoids in the ginkgo flavonoid product / mass of dried ginkgo leaf powder) × 100%; Purity = (Mass of ginkgo flavonoids in the ginkgo flavonoid product / Mass of the ginkgo flavonoid product) × 100%; Table 1. Yield and purity of Ginkgo flavonoids

[0034] The data in Table 1 show that using a deep eutectic solvent composed of N,N-dimethyl isopropanolamine, propylene glycol methyl ether and water as the extractant, combined with a process of first adsorbing with HPD-600 macroporous adsorption resin and then with AB-8 macroporous adsorption resin, can improve the yield and purity of ginkgo flavonoids.

[0035] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A green method for extracting ginkgo flavonoids from ginkgo, characterized in that, Includes the following steps: S1. Dry and pulverize the ginkgo leaves to obtain ginkgo leaf powder; S2. Mix the dried ginkgo leaf powder with a deep eutectic solvent extractant, extract, and then centrifuge to obtain the extract; S3. After adsorption and purification of the extract, ginkgo flavonoid eluent is obtained; S4. The ginkgo flavonoid eluent is concentrated and dried to obtain the ginkgo flavonoid product; The deep eutectic solvent extractant includes N,N-dimethylisopropanolamine, propylene glycol methyl ether, and water.

2. The green method for extracting ginkgo flavonoids from ginkgo according to claim 1, characterized in that, The molar ratio of N,N-dimethylisopropanolamine to propylene glycol methyl ether is 1~2:

1.

3. The green method for extracting ginkgo flavonoids from ginkgo according to claim 1, characterized in that, The preparation method of the deep eutectic solvent extractant includes the following steps: mixing N,N-dimethylisopropanolamine, propylene glycol methyl ether and water until it becomes a transparent liquid to obtain the deep eutectic solvent extractant.

4. A green method for extracting ginkgo flavonoids from ginkgo according to claim 3, characterized in that, In the deep eutectic solvent extractant, the mass of water is 10% to 30% of the sum of the masses of N,N-dimethylisopropanolamine and propylene glycol methyl ether.

5. A green method for extracting ginkgo flavonoids from ginkgo according to claim 3, characterized in that, The mixing temperature is 80~90℃.

6. A green method for extracting ginkgo flavonoids from ginkgo according to claim 1, characterized in that, In step S3, the adsorption purification includes the following steps: after the extract is adsorbed by macroporous adsorption resin I, it is washed with water and then eluted with eluent I. After collecting the eluent, it is adsorbed by macroporous adsorption resin II, washed with water and then eluted with eluent II to obtain ginkgo flavonoid eluent. The macroporous adsorption resin I and macroporous adsorption resin II are each independently one or two of HPD-600 resin and AB-8 resin.

7. A green method for extracting ginkgo flavonoids from ginkgo according to claim 6, characterized in that, The macroporous adsorption resin I is HPD-600 macroporous adsorption resin; the macroporous adsorption resin II is AB-8 macroporous adsorption resin.

8. A green method for extracting ginkgo flavonoids from ginkgo according to claim 1, characterized in that, In step S2, the mass-to-volume ratio of the dried ginkgo leaf powder and the deep eutectic solvent extractant is 1g:8~12mL.

9. A green method for extracting ginkgo flavonoids from ginkgo according to claim 1, characterized in that, In step S2, the extraction temperature is 40~50℃ and the time is 30~60min.

10. A green method for extracting ginkgo flavonoids from ginkgo according to claim 1, characterized in that, In step S2, the relative centrifugal force is 10000~12000g, and the time is 15~25min.

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