Glucosyl modified quercetin and preparation method thereof

Abstract

The invention discloses glucosyl modified quercetin and a preparation method of the glucosyl modified quercetin. The invention provides glucosyl modified quercetin, and the glucosyl modified quercetin is prepared by the following method, the method comprises the following steps: in a solvent, in the presence of a mixed enzyme, rutin and a glycosyl donor are subjected to a reaction to obtain the glucosyl modified quercetin, the glycosyl donor is beta-cyclodextrin and / or maltodextrin; the mixed enzyme is rhamnosidase and cyclodextrin glucosyltransferase; the mass ratio of the cyclodextrin glucosyltransferase to the rhamnosidase is (2 to 4) to 1. The method has the advantages of high yield and high content of glucosyl modified isoquercetin.

Description

Technical Field

[0001] The present invention relates to the field of natural product chemistry, and particularly to a glucose-modified quercetin and a preparation method thereof. Background Art

[0002] In recent years, enzymatically modified isoquercitrin (EMIQ), a derivative of quercetin modified with multiple glucosyl groups, has come into the view of the scientific research community. This substance is a derivative obtained by catalyzing isoquercitrin with cyclodextrin glucosyltransferase, attaching 1 - 12 glucoside units thereto (Biol Pharm Bull. 2009; 32(12): 2034 - 2040.).

[0003]

[0004] Due to this enzymatic modification, EMIQ not only has a significantly improved solubility (Food Chem. 2017, 229, 75–83), but also has a significantly enhanced bioavailability (Arch Biochem Biophys. 2010; 501(1): 91 - 97.). This not only expands its application scope in cosmetics, medicine, and health products, but also makes it show more excellent effects in terms of biological activities, such as antioxidant properties (Arch Toxicol 84, 143–153(2010)). Therefore, developing an economical and efficient preparation method for EMIQ has become one of the research hotspots in the fields of medicine, health products, and cosmetics.

[0005] Sophora japonica pollen has the effects of clearing heat and reducing blood pressure, anti - inflammation, hemostasis, and relieving cough and dispelling phlegm. Sophora japonica pollen contains quercetin and quercetin glycoside derivatives (such as rutin), which are flavonoid substances commonly present in the fruits, flowers, stems, leaves, etc. of plants, and have good anti - tumor, antioxidant, anti - inflammatory, and cardiovascular disease prevention effects. It has been applied in the fields of food, medicine, cosmetics, etc. However, quercetin and its derivatives such as rutin and isoquercetin have poor water solubility, resulting in low bioavailability and many limitations in actual use. To improve their water solubility, some delivery systems have been developed and utilized. Microemulsion preparations, nanoparticles, nanococrystals, liposomes, etc. are usually used to encapsulate quercetin and its derivatives. However, these methods still face problems such as side effects of surfactants, high packaging material costs, complex preparation processes of high - speed shear and homogenization micro - jet, and limited selection of cocrystals. Some methods only stay at the laboratory stage.

[0006] Patent CN 114686549 A discloses a method for preparing enzymatically modified isoquercitrin from rutin, which uses water as a solvent and a complex enzyme to obtain enzymatically modified isoquercitrin from rutin. However, the types of dextrin, the types of complex enzymes, and the ratio between the complex enzymes used in this patent are not disclosed, and it is difficult for those skilled in the art to repeat this method from the disclosed content. Moreover, it can be seen from the HPLC chromatogram published in the patent that the claim in the patent that the content of enzymatically modified isoquercitrin is as high as 100% is inaccurate. The content of isoquercitrin in its product accounts for 36.7% - 44.3%, and it is not completely glycosylated isoquercitrin. Generally, in enzymatically modified isoquercitrin, the lower the content of isoquercitrin, the more beneficial it is to improve its water solubility.

[0007] Therefore, from the perspectives of economy and process method, the present invention develops a method for extracting quercetin glycoside derivatives from sophora flower powder, with a high degree of glycosylation, so that the obtained quercetin glycoside derivatives have good water solubility. Summary of the Invention

[0008] The technical problem to be solved by the present invention is that the preparation method of quercetin modified by glucosyl in the prior art has a low yield and a high content of isoquercitrin. To this end, the present invention provides a quercetin modified by glucosyl and its preparation method. This method has the advantages of high yield and a high content of isoquercitrin modified by glucosyl.

[0009] The present invention provides a method for preparing quercetin modified by glucosyl, which includes the following steps: in a solvent, in the presence of a mixed enzyme, reacting rutin with a glycosyl donor to obtain quercetin modified by glucosyl;

[0010] The glycosyl donor is β-cyclodextrin and / or maltodextrin;

[0011] The mixed enzyme is rhamnosidase and cyclodextrin glucosyltransferase;

[0012] The mass ratio of the cyclodextrin glucosyltransferase to the rhamnosidase is (2 - 4):1.

[0013] In a certain embodiment, the quercetin modified by glucosyl can be the quercetin modified by glucosyl as shown in Formula II;

[0014]

[0015] Said n is at least 0, 1, 2, 3, 4, 5, 6 and 7; for example, n is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11. (Said n is at least 0, 1, 2, 3, 4, 5, 6 and 7 means that the quercetin glucoside modification shown in Formula II is a mixture, and its components include isoquercetin (i.e., when n is 0), and multiple quercetin glucoside components when n is 0, 1, 2, 3, 4, 5, 6 and 7 respectively.)

[0016] In a certain embodiment, in the quercetin glucoside modification, the content ratio of isoquercetin is 0 - 30%, for example 0 - 25%, and for another example it is 24.68%.

[0017] Said solvent is a conventional solvent for such reactions in the art, for example a buffer solution or water, and for another example water.

[0018] In a certain embodiment, said buffer solution can be a phosphate buffer solution or a sodium acetate buffer solution.

[0019] In a certain embodiment, the volume - mass ratio of said solvent to said rutin can be (5 - 30) mL / g, for example (5 - 20) mL / g, and for another example 10 mL / g.

[0020] In a certain embodiment, the mass ratio of said glycosyl donor to said rutin can be (1 - 5):1, for example (1 - 3):1, and for another example 1:1 or 2:1, and preferably 2:1.

[0021] In a certain embodiment, the mass ratio of said mixed enzyme to said rutin can be (0.01 - 0.07):1, for example (0.03 - 0.06):1, and for another example 0.03:1 or 0.06:1, and preferably 006:1.

[0022] In a certain embodiment, the mass ratio of said cyclodextrin glucosyltransferase to said rhamnosidase can be 2:1 or 4:1, and preferably 2:1.

[0023] In a certain embodiment, the temperature of said reaction is 45°C - 65°C, for example 50°C - 55°C; and for another example 53°C.

[0024] In a certain embodiment, the process of said reaction ends when there is no insoluble matter; preferably, the time of said reaction is 10 - 40 h, for example 25 - 35 h, and for another example 32 h.

[0025] Said reaction may further include post - treatment. Preferably, said post - treatment includes one or more of the following steps: enzyme inactivation, suction filtration, light - avoiding refrigeration, fine filtration, sterilization and drying;

[0026] Said enzyme inactivation can be achieved by heating to 90°C for enzyme inactivation, and the enzyme inactivation time can be 15 min;

[0027] The temperature for light-shielded refrigeration can be 0 to 4°C, and the time for light-shielded refrigeration can be 48 hours;

[0028] The fine filtration can be carried out by using a microporous filtration membrane with a pore size of 0.25 microns;

[0029] The drying can be freeze-drying.

[0030] In one embodiment, the preparation method of the glucose-modified quercetin may further include the preparation method of rutin, and the preparation method of rutin includes the following steps: mixing sophora flower pollen with a solvent and then performing extraction to obtain rutin.

[0031] In one embodiment, the solvent can be water.

[0032] In one embodiment, the temperature for extraction can be 90 - 110°C, for example, 100°C.

[0033] In one embodiment, the volume-mass ratio of the solvent to the sophora flower pollen can be (5 - 30) mL / g, for example, (20 - 30) mL / g, for example, 25 mL / g.

[0034] In one embodiment, the preparation method of rutin may further include the following post-treatment steps: filtration and concentration.

[0035] The present invention also provides a glucose-modified quercetin, which is prepared by the following method. The method includes the following steps: reacting rutin and a glycosyl donor in a solvent in the presence of a mixed enzyme to obtain the glucose-modified quercetin;

[0036] The glycosyl donor is β-cyclodextrin and / or maltodextrin;

[0037] The mixed enzyme is rhamnosidase and cyclodextrin glucosyltransferase;

[0038] The mass ratio of the cyclodextrin glucosyltransferase to the rhamnosidase is (2 - 4):1.

[0039] The glucose-modified quercetin can be as described in any one of the present invention.

[0040] The operations and conditions of the method can also be as described in any one of the present invention.

[0041] In one embodiment, in the glucose-modified quercetin, the content ratio of isoquercetin is 0 - 30%, and the content ratio of the glucose-modified quercetin shown in Formula II is 70% - 100%; preferably, the content ratio of isoquercetin is 25 - 30%, and the content ratio of the glucose-modified quercetin shown in Formula II is 70% - 75%.

[0042] On the basis of not violating the common sense in this field, the above preferred conditions can be combined arbitrarily to obtain various preferred examples of the present invention.

[0043] The reagents and raw materials used in the present invention are all commercially available.

[0044] The positive and progressive effects of the present invention are as follows: The preparation method of the quercetin modified with glucoside provided by the present invention has the advantages of high yield and high content. Further, in the quercetin modified with glucoside obtained in this application, the content of isoquercetin is low and the degree of glycosylation of isoquercetin is higher, which is more conducive to improving the water solubility and bioavailability of the quercetin modified with glucoside. Description of the drawings:

[0045] Figure 1 : HPLC analysis result diagram of the quercetin modified with glucoside obtained in Example 5. Detailed implementation manners

[0046] The present invention will be further described below by way of examples, but the present invention is not limited to the scope of the described examples. The experimental methods without specific conditions noted in the following examples are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0047] Sophora japonica pollen: Xi'an Shennong Biotechnology Co., Ltd., 20230516

[0048] β-cyclodextrin: Henan Ming'ang Food Ingredients Co., Ltd., 202210

[0049] Maltodextrin: Henan Ming'ang Food Ingredients Co., Ltd., 202307

[0050] Cyclodextrin glucosyltransferase: Novozymes (China), ACN00273

[0051] Rhamnosidase: Cangzhou Xiasheng Enzyme, 42304110

[0052] The calculation method of the product yield in the present invention is as follows:

[0053]

[0054] Taking 250 grams of rutin as an example, after complete glycosylation (i.e., on average, two sugar groups are added), the theoretical product mass is 322.6 grams. For example, in Example 1, the product is 229.2 grams, and the yield is 71% (= 229.2 grams / 322.6 grams).

[0055] Calculation method of the content of quercetin modified with glucoside: Divide the sum of the integration areas of the main components in the HPLC chromatogram by the sum of the total areas and multiply by 100%.

[0056] Example 1

[0057] Take 1.0 kg of sophora flower powder in a 5000 mL beaker, add 2500 mL of boiling water, boil for 30 min, continuously supplement the evaporated water, filter while it is hot, then extract with 2500 mL of boiling water for 20 min, combine the two filtrates, concentrate the volume to 1 / 2, let it stand overnight to obtain the initial sophora flower extract, refrigerate after standing, filter to obtain 250.0 g of rutin with a purity of 96%; dissolve the obtained rutin in 2.5 L of water, add 250.0 g of β-cyclodextrin, complex enzyme (1.25 g of rhamnosidase, 5.0 g of cyclodextrin glucosyltransferase), heat up to 53 °C and stir for 32 h, then heat up to 90 °C to inactivate the enzyme for 15 min, after returning to room temperature, filter through a Buchner funnel to remove insoluble substances, let the obtained filtrate stand in the dark at 0 - 4 °C for 2 days, quickly filter under reduced pressure at low temperature (below 15 °C), the filtrate is finely filtered using a 0.25 μm microporous filter membrane, separated by macroporous resin, and freeze-dried to obtain 229.2 g of the product with a yield of 71%, and the content of quercetin modified with glucosyl is 95%.

[0058] Example 2

[0059] Take 1.0 kg of sophora flower powder in a 5000 mL beaker, add 2500 mL of boiling water, boil for 30 min, continuously supplement the evaporated water, filter while it is hot, then extract with 2500 mL of boiling water for 20 min, combine the two filtrates, concentrate the volume to 1 / 2, let it stand overnight to obtain the initial sophora flower extract, refrigerate after standing, filter to obtain 250.0 g of rutin with a purity of 96%; dissolve the obtained rutin in 2.5 L of water, add 250 g of β-cyclodextrin, complex enzyme (2.5 g of rhamnosidase, 5 g of cyclodextrin glucosyltransferase), heat up to 53 °C and stir for 32 h, then heat up to 90 °C to inactivate the enzyme for 15 min, after returning to room temperature, filter through a Buchner funnel to remove insoluble substances, let the obtained filtrate stand in the dark at 0 - 4 °C for 2 days, quickly filter under reduced pressure at low temperature (below 15 °C), the filtrate is finely filtered using a 0.25 μm microporous filter membrane, separated by macroporous resin, and freeze-dried to obtain 255.1 g of the product with a yield of 79%, and the content of quercetin modified with glucosyl is 95%.

[0060] Example 3

[0061] Take 1.0 kg of sophora flower powder in a 5000 mL beaker, add 2500 mL of boiling water, boil for 30 min, continuously supplement the evaporated water, filter while it is hot, then extract with 2500 mL of boiling water for 20 min. Combine the two filtrates, concentrate the volume to 1 / 2, let it stand overnight to obtain the initial sophora flower extract. After standing, refrigerate, and filter to obtain 250.0 g of rutin with a purity of 96%. Dissolve the obtained rutin in 2.5 L of water, add 250 g of β-cyclodextrin, and complex enzymes (5 g of rhamnosidase and 10 g of cyclodextrin glucanotransferase). Heat to 53 °C and stir for 32 h, then heat to 90 °C to inactivate the enzymes for 15 min. Filter through a Buchner funnel to remove insoluble substances. The obtained filtrate is placed in the dark and refrigerated at 0 - 4 °C for 2 days, and then quickly filtered under reduced pressure at low temperature (below 15 °C). The filtrate is finely filtered using a 0.25-micron microporous filter membrane, separated by macroporous resin, and freeze-dried to obtain a product with a mass of 268.0 g and a yield of 83%, and the content of quercetin modified with glucose groups is 96%.

[0062] Example 4

[0063] Take 1.0 kg of sophora flower powder in a 5000 mL beaker, add 2500 mL of boiling water, boil for 30 min, continuously supplement the evaporated water, filter while it is hot, then extract with 2500 mL of boiling water for 20 min. Combine the two filtrates, concentrate the volume to 1 / 2, let it stand overnight to obtain the initial sophora flower extract. After standing, refrigerate, and filter to obtain 250.0 g of rutin with a purity of 96%. Dissolve the obtained rutin in 2.5 L of water, add 500 g of β-cyclodextrin, and complex enzymes (2.5 g of rhamnosidase and 5 g of cyclodextrin glucanotransferase). Heat to 53 °C and stir for 32 h, then heat to 90 °C to inactivate the enzymes for 15 min. Filter through a Buchner funnel to remove insoluble substances. The obtained filtrate is placed in the dark and refrigerated at 0 - 4 °C for 2 days, and then quickly filtered under reduced pressure at low temperature (below 15 °C). The filtrate is finely filtered using a 0.25-micron microporous filter membrane, separated by macroporous resin, and freeze-dried to obtain a product with a mass of 274.4 g and a yield of 85%, and the content of quercetin modified with glucose groups is 96%.

[0064] Example 5

[0065] Take 1.0 kg of Sophora japonica flower powder in a 5000 mL beaker, add 2500 mL of boiling water, boil for 30 min, continuously supplement the evaporated water, filter while it is hot, then extract with 2500 mL of boiling water for 20 min, combine the two filtrates, concentrate the volume to 1 / 2, let it stand overnight to obtain the initial extract of Sophora japonica flower. After standing, refrigerate it, filter to obtain 250.0 g of rutin with a purity of 96%; dissolve the obtained rutin in 2.5 L of water, add 500 g of β-cyclodextrin, compound enzyme (5.0 g of rhamnosidase, 10 g of cyclodextrin glucosyltransferase), heat up to 53 °C and stir for 32 h, then heat up to 90 °C to inactivate the enzyme for 15 min, filter with a Buchner funnel to remove insoluble substances, place the obtained filtrate in the dark and refrigerate at 0 - 4 °C for 2 days, quickly filter under reduced pressure at low temperature (below 15 °C), filter the filtrate through a 0.25-micron microporous filter membrane for fine filtration, separate by macroporous resin, and then freeze-dry to obtain a product with a mass of 300.3 g and a yield of 93%, and the content of quercetin modified with glucosyl is 98.3%.

[0066] The HPLC analysis results of the quercetin modified with glucosyl obtained in this example are as Figure 1 shown in Table 1 and

[0067] Table 1

[0068]

[0069] Calculating the peak area ratio of each component based on the total peak area of the component quercetin-(Glu) 1-8 being 100%, the results are shown in Table 2

[0070] Table 2

[0071]

[0072] The content of isoquercetin in the enzyme-modified quercetin in Patent CN 114686549 A is 36.36% - 44.3%. From the analysis results of Table 1 and Table 2, it can be seen that the content of isoquercetin in the product quercetin modified with glucosyl obtained in this invention is significantly lower than that in Patent CN 114686549 A. In the quercetin modified with glucosyl obtained in this application, the degree of glycosylation of isoquercetin is higher, which is more conducive to improving the water solubility and bioavailability of quercetin modified with glucosyl.

[0073] Example 6

[0074] Take 1.0 kg of sophora flower powder in a 5000 mL beaker, add 2500 mL of boiling water, boil for 30 min, continuously supplement the evaporated water, filter while it is hot, then extract with 2500 mL of boiling water for 20 min, combine the two filtrates, concentrate the volume to 1 / 2, let it stand overnight to obtain the initial sophora flower extract, refrigerate after standing, and filter to obtain 250.0 g of rutin; dissolve the obtained rutin in 2.5 L of water, add 500 g of maltodextrin and a complex enzyme (5.0 g of rhamnosidase and 10 g of cyclodextrin glucanotransferase), raise the temperature to 53 °C and stir for 32 h, then raise the temperature to 90 °C to inactivate the enzyme for 15 min, filter with a Buchner funnel to remove insoluble substances, let the obtained filtrate stand in the dark at 0 - 4 °C for 2 days, quickly filter under reduced pressure at low temperature (below 15 °C), finely filter the filtrate with a 0.25 - micron microporous filter membrane, separate with macroporous resin, and freeze - dry to obtain a product with a mass of 297.0 g, a yield of 92%, and the content of quercetin modified with glucose groups is 96%.

[0075] Comparative Example 1:

[0076] Take 1.0 kg of sophora flower powder in a 5000 mL beaker, add 2500 mL of boiling water, boil for 30 min, continuously supplement the evaporated water, filter while it is hot, then extract with 2500 mL of boiling water for 20 min, combine the two filtrates, concentrate the volume to 1 / 2, let it stand overnight to obtain the initial sophora flower extract, refrigerate after standing, and filter to obtain 250.0 g of rutin with a purity of 96%; dissolve the obtained rutin in 2.5 L of water, add 5.0 g of rhamnosidase, raise the temperature to 53 °C, stir for 4 h, then filter and dry to separate 178.6 g of isoquercetin with a yield of 94%, add 10 g of cyclodextrin glucanotransferase, raise the temperature to 53 °C and stir for 32 h, then raise the temperature to 90 °C to inactivate the enzyme for 15 min, filter with a Buchner funnel to remove insoluble substances, let the obtained filtrate stand in the dark at 0 - 4 °C for 2 days, quickly filter under reduced pressure at low temperature (below 15 °C), finely filter the filtrate with a 0.25 - micron microporous filter membrane, separate with macroporous resin, and freeze - dry to obtain 218.5 g of quercetin modified with glucose groups with a yield of 72%.

[0077] The above - described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A preparation method of glucose-modified quercetin, characterized in that, It includes the following steps: In a solvent, in the presence of a mixed enzyme, react rutin with a glycosyl donor to obtain glucosyl-modified quercetin; The glycosyl donor is β-cyclodextrin and / or maltodextrin; The mixed enzyme is rhamnosidase and cyclodextrin glucosyltransferase; The mass ratio of the cyclodextrin glucosyltransferase to the rhamnosidase is (2 - 4):

1.

2. The preparation method of the glucose-modified quercetin according to claim 1, characterized in that, It satisfies one or more of the following conditions: (1) The solvent is a buffer solution or water; the buffer solution can be a phosphate buffer solution or a sodium acetate buffer solution; (2) The volume-mass ratio of the solvent to the rutin is (5 - 30) mL / g; (3) The mass ratio of the glycosyl donor to the rutin is (1 - 5):1; (4) The mass ratio of the mixed enzyme to the rutin is (0.01 - 0.07):1; (5) The mass ratio of the cyclodextrin glucosyltransferase to the rhamnosidase is 2:1 or 4:1; (6) The temperature of the reaction is 45°C - 65°C; and (7) The glycosylation reaction further includes post-treatment, and the post-treatment includes one or more of the following steps: enzyme inactivation, suction filtration, light-shielded refrigeration, fine filtration, sterilization, and drying.

3. The preparation method of the glucose-modified quercetin according to claim 2, wherein, It satisfies one or more of the following conditions: (1) The solvent is water; (2) The volume-mass ratio of the solvent to the rutin is (5 - 20) mL / g; (3) The mass ratio of the glycosyl donor to the rutin is (1 - 3):1; (4) The mass ratio of the mixed enzyme to the rutin is (0.03 - 0.06):1; (5) The temperature of the reaction is 50°C - 55°C; (6) The enzyme inactivation is to inactivate the enzyme by heating to 90°C; (7) The enzyme inactivation time is 15 min; (8) The temperature of the light-shielded refrigeration is 0 - 4°C; (9) The time of the light-shielded refrigeration is 48 hours; (10) The fine filtration is to filter finely with a 0.25-micron microporous filtration membrane; and (11) The drying is freeze-drying.

4. The preparation method of the glucose-modified quercetin according to claim 3, wherein, It satisfies one or more of the following conditions: (1) The volume-mass ratio of the solvent to the rutin is 10 mL / g; (2) The mass ratio of the glycosyl donor to the rutin is 1:1 or 2:1; (3) The mass ratio of the mixed enzyme to the rutin is 0.03:1 or 0.06:1; and (4) The temperature of the reaction is 53°C.

5. The preparation method of the glucose-modified quercetin according to any one of claims 1-4, characterized in that, The preparation method of the glucosyl-modified quercetin further includes the preparation method of rutin, and the preparation method of rutin includes the following steps: Mix sophora flower pollen with a solvent and then perform extraction to obtain rutin.

6. The preparation method of the glucose-modified quercetin according to claim 5, wherein, The preparation method of the rutin satisfies one or more of the following conditions: (1) The solvent is water; (2) The temperature of the extraction is 90 - 110°C, such as 100°C; (3) The volume-mass ratio of the solvent to the sophora flower pollen is (5 - 30) mL / g, such as (20 - 30) mL / g, and further such as 25 mL / g; and (4) The preparation method of the rutin further includes the following post-treatment steps: filtration and concentration.

7. The preparation method of the glucose-modified quercetin according to claim 1, characterized in that, The glucosyl-modified quercetin is the glucosyl-modified quercetin shown in Formula II; n is at least 0, 1, 2, 3, 4, 5, 6, and 7.

8. The preparation method of the glucose-modified quercetin according to claim 7, characterized in that, The n is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11.

9. The preparation method of the glucose-modified quercetin according to claim 1, 7 or 8, characterized in that, In the glucosyl-modified quercetin, the content proportion of isoquercetin is 0-30%, such as 0-25%, and further such as 24.68%.

10. A glucose-modified quercetin, characterized in that the glucose-modified quercetin is prepared by the following method, and the method comprises the following steps: In a solvent, in the presence of a mixed enzyme, rutin and a glycosyl donor are reacted to obtain glucosyl-modified quercetin; The glycosyl donor is β-cyclodextrin and / or maltodextrin; The mixed enzyme is rhamnosidase and cyclodextrin glucosyltransferase; The mass ratio of the cyclodextrin glucosyltransferase to the rhamnosidase is (2-4):1; The glucosyl-modified quercetin can be as described in any one of claims 7-9; The operations and conditions of the preparation method of the glucosyl-modified quercetin can also be as described in any one of claims 2-6.

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