Refining method of quercetagetin

Abstract

The invention relates to the technical field of plant extract purification, in particular to a refinement method of quercetagetin. The invention provides a refining method for preparing high-purity quercetagetin from a quercetagetin crude extract, and the method is different from a chromatographic separation scheme and other schemes, and has the advantages of low cost and industrialization; by utilizing the method, the high-purity quercetagetin can be prepared, a relatively high quercetagetin yield can be ensured, the problem that the high-purity quercetagetin can only be obtained from plant raw materials or depends on chromatographic separation and purification in the prior art is solved, and the method has a relatively good application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of plant extract purification, and particularly relates to a refining method of quercetagetin. BACKGROUND

[0002] In the prior art, the preparation method of quercetagetin is usually directly extracted from marigold flowers, and especially, lutein and quercetagetin are simultaneously extracted from marigold flowers, such as Chinese patent applications 201910406196.7, 202210741682.6, 201911007661.6 and 201910579586.4. However, when quercetagetin is extracted from marigold flowers alone, it is necessary to rely on a chromatography purification method to obtain high-purity quercetagetin (such as Chinese patent application 201410708334.4). Due to the limitation of the processing capacity of chromatography purification, the method cannot be applied to industrial production.

[0003] At present, there are still few methods for preparing high-purity quercetagetin from marigold flower meal remaining after lutein extraction. Chinese patent application 201610108596.6 discloses a method for preparing quercetagetin by extraction, centrifugal filtration, concentration, centrifugal filtration and multiple water washing purification. However, the method is not only complicated, but also the purity of quercetagetin can only reach about 88% at most. At present, there is no method for refining the quercetagetin crude extract obtained from marigold flower meal after lutein extraction to obtain high-purity (more than 90%) quercetagetin and suitable for industrialization. SUMMARY

[0004] The present application provides a refining method of quercetagetin.

[0005] The present application develops a refining method capable of obtaining high-purity quercetagetin, taking the crude extract obtained by separately extracting quercetagetin from marigold flowers or the crude extract obtained by extracting xanthophyll or ester thereof from marigold flowers as raw material. In the development process, the present application finds that when xanthophyll or ester thereof and quercetagetin are simultaneously extracted from marigold flowers, only a small amount of impurities is dissolved into the extract, and then the crude extract obtained can obtain high-purity quercetagetin through simple refining treatment; when quercetagetin is extracted alone (i.e. xanthophyll or ester thereof and quercetagetin are not simultaneously extracted), or when marigold flower meal after extracting xanthophyll or ester thereof is used as raw material, no matter how the extracting agent is adjusted, the types and content of impurities dissolved into the quercetagetin crude extract significantly increase, which makes it difficult to effectively remove the impurities by using conventional impurity washing and extraction methods, and it is necessary to rely on chromatographic purification to obtain high-purity quercetagetin. In view of the above problems of the specific raw material, the present application continuously optimizes and adjusts the refining method, and provides a low-cost and industrialized refining method which is simple, efficient and can obtain high-purity quercetagetin without relying on chromatographic purification, for the quercetagetin crude extract obtained by separately extracting quercetagetin or the quercetagetin crude extract obtained by extracting xanthophyll or ester thereof from marigold flower meal.

[0006] Specifically, the present application provides the technical solutions described below.

[0007] The present application provides a refining method of quercetagetin, which comprises: sequentially performing first impurity washing treatment and second impurity washing treatment on quercetagetin crude extract, and then performing dissolution treatment and precipitation separation treatment. The first impurity washing treatment uses a non-polar organic solvent for impurity washing, and the non-polar organic solvent comprises at least one selected from n-hexane, petroleum ether and cyclohexane. The second impurity washing treatment uses a polar organic solvent aqueous solution for impurity washing, and the volume fraction of the polar organic solvent in the aqueous solution is 15%-35%, and the polar organic solvent comprises at least one selected from methanol, ethanol, propanol and acetone. The dissolution treatment is to dissolve quercetagetin with a polar organic solvent or an aqueous solution thereof, and separate the supernatant. The precipitation separation treatment is to mix the supernatant with water, and collect the solid after separation; the mixing with water is to slowly add water to the supernatant, and the amount of water added is to make the volume fraction of the polar organic solvent used in the dissolution treatment in the system be 45%-65%, and the slow water adding is to add water for not less than 20 min.

[0008] In the present application, the quercetagetin crude extract is obtained from the marigold meal after extracting xanthophyll or ester thereof, or is obtained when quercetagetin is extracted from marigold flowers alone; wherein the extraction is performed using a polar organic solvent or its aqueous solution.

[0009] In the present application, the crude extract refers to a low-content quercetagetin extract obtained by extraction (e.g. solvent extraction) or further simple or preliminary purification.

[0010] Preferably, the content of quercetagetin in the quercetagetin crude extract is not less than 40%, preferably not less than 50%. For the quercetagetin crude extract with quercetagetin content in the range, the refining method of the present application can achieve good refining effect and obtain quercetagetin with high purity.

[0011] For the quercetagetin crude extract obtained from the marigold meal after extracting xanthophyll or ester thereof, or obtained when quercetagetin is extracted from marigold flowers alone, the existing non-chromatographic separation refining method can achieve good refining effect in high-content crude extract. The advantage of the present application is that it can still achieve good refining effect for low-content crude extract, obtain quercetagetin with purity not less than 95%, and ensure high yield. Therefore, preferably, the content of quercetagetin in the quercetagetin crude extract is not higher than 85%. More preferably, not higher than 80%, more preferably not higher than 70%.

[0012] Preferably, the content of xanthophyll or ester thereof in the quercetagetin crude extract is less than 5%, more preferably less than 1%, more preferably less than 0.5%, more preferably less than 0.1%.

[0013] The present application is verified by a large number of experiments, and it is found that, for the above quercetagetin crude extract, first, two specific solvent washing is carried out in turn, then the quercetagetin in the crude extract is dissolved by using a polar organic solvent or its aqueous solution, then water is added for precipitation treatment and the water adding time is controlled, the quercetagetin can be efficiently precipitated, and few impurities are precipitated, which is beneficial to better remove impurities, improve the purity of quercetagetin and ensure the yield. The water adding time and the concentration of the polar organic solvent used in the dissolution treatment after water adding in the system are the key factors affecting the precipitation of quercetagetin and impurities, and controlling the water adding time and the concentration of the polar organic solvent used in the dissolution treatment after water adding in the system within the range described in the present application can effectively improve the purity of quercetagetin and ensure a high yield. For low content quercetagetin crude extract, two-step washing treatment is carried out before dissolution treatment, which can reduce the impurity content in quercetagetin, ensure higher dissolution efficiency and higher purity quercetagetin precipitation in the later stage; the effect of removing impurities according to the order of non-polar organic solvent washing and then polar solvent washing is better. Preferably, the slow water adding is water adding at a fixed flow rate.

[0014] The flow rate of water adding can be adjusted according to the size of the reaction system and the amount of water adding, and the present application does not have special limitations, as long as the above water adding time is controlled.

[0015] Preferably, the amount of water added is such that the volume fraction of the polar organic solvent in the precipitation separation system is 45%-58%.

[0016] Preferably, after the water adding is completed, the static treatment is continued for 1-3h, and the solid is collected after separation.

[0017] For the polar organic solvent for dissolving quercetagetin, it can be selected from alcohol, ketone, or aqueous solution of the above two.

[0018] In the dissolution treatment step of the above method, the polar organic solvent includes at least one selected from methanol, ethanol, propanol, and acetone. Preferably, it is methanol and / or acetone.

[0019] Preferably, the dissolution treatment is carried out by using an aqueous solution of a polar organic solvent, and in the aqueous solution, the volume fraction of the polar organic solvent is greater than 85%; more preferably, it is 85%-99%.

[0020] Preferably, the solid-liquid ratio of the dissolution treatment is 1kg:10-100L (preferably 1kg:10-20L); the temperature is 30-60℃ (preferably 40-60℃); and the treatment time is 6-12h.

[0021] In the above method, the separation (supernatant or solid) method includes one or more of centrifugation, filtration (such as plate and frame filtration, etc.).

[0022] In the first washing and impurity removing step of the method, the non-polar organic solvent is preferably n-hexane or petroleum ether.

[0023] In the second washing and impurity removing step of the method, the polar organic solvent is preferably methanol and / or acetone. More preferably, the polar organic solvent is methanol.

[0024] The refining method uses a combination of two different solvents to cooperatively dissolve and precipitate crystals, and through the synergistic effects of the four steps, the content of quercetagetin in the crude extract can be increased to a purity of not less than 95%, and at the same time, the yield of quercetagetin is greater than 90%.

[0025] Preferably, after the first washing and impurity removing step, the solid is separated, and the residual non-polar organic solvent in the solid is less than 1%; after the second washing and impurity removing step, the solid is separated, and the residual volatile substance in the solid is less than 30%.

[0026] Preferably, the temperature of the first washing and impurity removing step is 20-45℃; the washing and impurity removing time is 2-6h; and the solid-liquid ratio is 1kg:4-10L.

[0027] Preferably, the temperature of the second washing and impurity removing step is 50-70℃; the washing and impurity removing time is 6-12h; and the solid-liquid ratio is 1kg:5-15L.

[0028] In the present application, the solid-liquid ratio refers to the ratio of the mass (g) of the material to be treated to the volume (mL) of the treatment reagent.

[0029] In the above method, after the first washing and impurity removing step, the solid is separated, and the separated solid is subjected to the second washing and impurity removing step, the solid is separated, and the solid is subjected to the dissolving treatment. The separation of the solid includes one or more of centrifugation, filtration (such as plate and frame filtration, etc.).

[0030] In some other embodiments of the present application, a refining method of quercetagetin is provided, which comprises the following steps: (1) a first washing and impurity removing step of quercetagetin crude extract using a non-polar organic solvent to separate a solid; (2) a second washing and impurity removing step of the solid obtained in step (1) using a polar organic solvent aqueous solution to separate a solid; (3) a dissolving step of the solid obtained in step (2) using a polar organic solvent aqueous solution to separate a supernatant; (4) slowly adding water to the supernatant obtained in step (3), and then separating and collecting the solid after standing.

[0031] In the present application, the content of quercetagetin in the quercetagetin crude extract is preferably not less than 50%.

[0032] Exemplarily, the quercetagetin crude extract prepared by the method comprises the following steps: taking the marigold flower, marigold flower meal, marigold flower granules or marigold flower meal granules, using 70-90% acetone aqueous solution as an extracting agent, taking the ratio of material to liquid as 1g:(4-10)mL, extracting at 45-55°C, extracting for 30-90 min each time, and extracting for 2-4 times; and then performing concentration and drying to obtain the quercetagetin crude extract, wherein the content of quercetagetin is not less than 50%.

[0033] The application further provides the quercetagetin prepared by the refining method.

[0034] Preferably, the purity of the quercetagetin is not less than 95%.

[0035] The application has at least the following beneficial effects: the application provides a refining method for preparing high-purity quercetagetin from quercetagetin crude extract, which is different from the scheme of chromatographic separation and has the advantages of low cost and industrialization; the method can be used to prepare quercetagetin with a purity of more than 95%, and can ensure a high yield of quercetagetin, thereby overcoming the problem that the prior art can only obtain high-purity quercetagetin from plant raw materials or relies on chromatographic separation and purification. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without any creative effort.

[0037] Figure 1 The liquid chromatogram of the quercetagetin refined by the method described in Example 1. DETAILED DESCRIPTION

[0038] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described clearly and completely in the following with reference to the drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort are within the scope of protection of the present application.

[0039] In the following examples, high-performance liquid chromatography is used to detect the content of quercetagetin in the refined quercetagetin product.

[0040] The conditions for high performance liquid chromatography detection are as follows: mobile phase: A phase is 2 ‰ phosphoric acid solution, B phase is acetonitrile, gradient elution is used for analysis (the conditions of gradient elution are shown in Table 1); the flow rate is controlled to be 1 mL / min during elution; the column temperature is 40 DEG C; the chromatographic column is CORTECS C18 column (4.6 mm x 50 mm, particle size 2.7 μm); the ultraviolet detector wavelength is 260 nm; and the injection amount is 2 μL.

[0041] Table 1

[0042] The content of lutein is detected by ultraviolet spectrophotometry at 474 nm.

[0043] The content calculation formula of quercetagetin is as follows: In the formula, X is the content of quercetagetin, %; A is the peak area of sample solution; K is the sample dilution multiple; E is the concentration of standard, g / mL; m is the mass of sample, g; C is the peak area of standard solution.

[0044] In the following examples, the yield calculation formula of quercetagetin is as follows: In the formula, X1 is the content of quercetagetin in the purified sample, %; X2 is the content of quercetagetin in the crude extract sample, %; M1 is the mass of the purified sample, g; M2 is the mass of the crude extract sample, g.

[0045] The preparation method of quercetagetin crude extract used in the following examples and comparative examples is as follows: The particles of marigold flowers or marigold flower meal are taken, the solid-liquid ratio is particles: 70% acetone aqueous solution = 1 g: 8 mL, extraction is carried out at 55 DEG C, each time for 60 min, and the extraction is carried out for 3 times; then concentration and drying are carried out to obtain quercetagetin crude extract, wherein the content of quercetagetin is 56.3%, and lutein is not detected.

[0046] Example 1 The present example provides a refining method of quercetagetin, which comprises the following steps: (1) Take 1 kg of quercetagetin crude extract, add 4 L of n-hexane solvent, stir at 45°C for 2 h, filter to obtain a filter cake of quercetagetin, at this time the content of quercetagetin is 62.7%; (2) Add 30% methanol aqueous solution to the filter cake of quercetagetin in step (1), the solid-liquid ratio is 1 kg:10 L, stir at 60°C for 8 h, and then perform suction filtration to obtain a filter cake of quercetagetin (the water content of the filter cake is less than 50%), at this time the dry basis content of quercetagetin is 83.5%; (3) Add 92% methanol aqueous solution to the filter cake of quercetagetin in step (2), the solid-liquid ratio is 1 kg:20 L, stir at 50°C for 8 h, and then perform filtration to obtain a supernatant; (4) Add 16 L of pure water to the supernatant in step (3) at a flow rate of 500 mL / min, stir while adding, stand at room temperature for 2 h, filter to obtain a filter cake of quercetagetin, at this time the dry basis content of quercetagetin is 97.9%. It is calculated that the yield of quercetagetin is 95.6%.

[0047] The high performance liquid chromatography detection results of quercetagetin obtained by the above refining method are shown in Table 1. Figure 1

[0048] Example 2 The embodiment provides a refining method of quercetagetin, which comprises the following steps: (1) Take 1 kg of quercetagetin crude extract, add 4 L of n-hexane solvent, stir at 45°C for 2 h, filter to obtain a filter cake of quercetagetin, at this time the content of quercetagetin is 62.7%; (2) Add 30% methanol aqueous solution to the filter cake of quercetagetin in step (1), the solid-liquid ratio is 1 kg:10 L, stir at 60°C for 8 h, and then perform suction filtration to obtain a filter cake of quercetagetin (the water content of the filter cake is less than 50%), at this time the dry basis content of quercetagetin is 83.5%; (3) Add 92% methanol aqueous solution to the filter cake of quercetagetin in step (2), the solid-liquid ratio is 1 kg:20 L, stir at 50°C for 8 h, and then perform filtration to obtain a supernatant; (4) Add 16 L of pure water to the supernatant in step (3) at a flow rate of 500 mL / min, stir while adding, stand at room temperature for 2 h, filter to obtain a filter cake of quercetagetin, at this time the dry basis content of quercetagetin is 97.9%. It is calculated that the yield of quercetagetin is 95.6%.

[0049] Example 3 The embodiment provides a refining method of quercetagetin, which comprises the following steps:​ (1) Take the crude extract of quercetagetin 1 kg, add petroleum ether solvent 10 L, stir at 20°C for 6 h, filter to obtain the filter cake of quercetagetin, at this time the content of quercetagetin is 61.5%; (2) Add 15% methanol aqueous solution to the filter cake of quercetagetin in step (1), the solid-liquid ratio is 1 kg:15 L, stir at 70°C for 12 h, suction filter to obtain the filter cake of quercetagetin (the water content of the filter cake is less than 50%), at this time the dry basis content of quercetagetin is 81.6%; (3) Add 95% acetone aqueous solution to the filter cake of quercetagetin in step (2), the solid-liquid ratio is 1 kg:20 L, stir at 50°C for 8 h, filter to obtain the supernatant; (4) Add pure water 16 L to the supernatant of step (3) at a flow rate of 500 mL / min, add while stirring, stand at room temperature for 2 h, filter to obtain the filter cake of quercetagetin, at this time the dry basis content of quercetagetin is 96.3%. It is calculated that the yield of quercetagetin is 96.6%.

[0050] Example 4 The present embodiment provides a refining method of quercetagetin, comprising the following steps: (1) Take the crude extract of quercetagetin 1 kg, add petroleum ether solvent 10 L, stir at 20°C for 6 h, filter to obtain the filter cake of quercetagetin, at this time the content of quercetagetin is 61.5%; (2) Add 15% methanol aqueous solution to the filter cake of quercetagetin in step (1), the solid-liquid ratio is 1 kg:15 L, stir at 70°C for 12 h, suction filter to obtain the filter cake of quercetagetin (the water content of the filter cake is less than 50%), at this time the dry basis content of quercetagetin is 81.6%; (3) Add 90% methanol aqueous solution to the filter cake of quercetagetin in step (2), the solid-liquid ratio is 1 kg:20 L, stir at 50°C for 6 h, filter to obtain the supernatant; (4) Add pure water 16 L to the supernatant of step (3) at a flow rate of 500 mL / min, add while stirring, stand at room temperature for 2 h, filter to obtain the filter cake of quercetagetin, at this time the dry basis content of quercetagetin is 97.3%. It is calculated that the yield of quercetagetin is 96.7%.

[0051] Example 5 The present embodiment provides a refining method of quercetagetin, comprising the following steps: (1) Take 1 kg of crude quercetagetin extract, add 10 L of petroleum ether solvent, stir at 20°C for 6 h, filter to obtain a filter cake of quercetagetin, at this time the content of quercetagetin is 61.5%; (2) Add 15% methanol aqueous solution to the filter cake of quercetagetin in step (1), the solid-liquid ratio is 1 kg: 15 L, stir at 70°C for 12 h, and then filter to obtain a filter cake of quercetagetin (the water content of the filter cake is less than 50%), at this time the dry basis content of quercetagetin is 81.6%; (3) Add 85% methanol aqueous solution to the filter cake of quercetagetin in step (2), the solid-liquid ratio is 1 kg: 10 L, stir at 60°C for 10 h, and then filter to obtain a supernatant; (4) Add 8 L of pure water to the supernatant of step (3) at a flow rate of 500 mL / min, stir while adding, and then stand at room temperature for 2 h, filter to obtain a filter cake of quercetagetin, at this time the dry basis content of quercetagetin is 95.8%. It is calculated that the yield of quercetagetin is 97.7%.

[0052] Example 6 The present embodiment provides a method for refining quercetagetin, comprising the following steps: (1) Take 1 kg of crude quercetagetin extract, add 10 L of petroleum ether solvent, stir at 20°C for 6 h, filter to obtain a filter cake of quercetagetin, at this time the content of quercetagetin is 61.5%; (2) Add 15% methanol aqueous solution to the filter cake of quercetagetin in step (1), the solid-liquid ratio is 1 kg: 15 L, stir at 70°C for 12 h, and then filter to obtain a filter cake of quercetagetin (the water content of the filter cake is less than 50%), at this time the dry basis content of quercetagetin is 81.6%; (3) Add 99% methanol aqueous solution to the filter cake of quercetagetin in step (2), the solid-liquid ratio is 1 kg: 20 L, stir at 40°C for 10 h, and then filter to obtain a supernatant; (4) Add 16 L of pure water to the supernatant of step (3) at a flow rate of 500 mL / min, stir while adding, and then stand at room temperature for 1 h, filter to obtain a filter cake of quercetagetin, at this time the dry basis content of quercetagetin is 99.4%. It is calculated that the yield of quercetagetin is 92.1%.

[0053] Example 7 The present embodiment provides a method for refining quercetagetin, comprising the following steps: (1) Take 1 kg of quercetagetin crude extract, add 10 L of petroleum ether solvent, stir at 20°C for 6 h, filter to obtain a filter cake of quercetagetin, at this time the content of quercetagetin is 61.5%; (2) Add 15% methanol aqueous solution to the filter cake of quercetagetin in step (1), the solid-liquid ratio is 1 kg: 15 L, stir at 70°C for 12 h, and then filter to obtain a filter cake of quercetagetin (the water content of the filter cake is less than 50%), at this time the dry basis content of quercetagetin is 81.6%; (3) Add 90% methanol aqueous solution to the filter cake of quercetagetin in step (2), the solid-liquid ratio is 1 kg: 20 L, stir at 50°C for 8 h, and then filter to obtain a supernatant; (4) Add 20 L of pure water to the supernatant of step (3) at a flow rate of 800 mL / min, stir while adding, and then stand at room temperature for 3 h, filter to obtain a filter cake of quercetagetin, at this time the dry basis content of quercetagetin is 96.8%. It is calculated that the yield of quercetagetin is 97.1%.

[0054] Example 8 The present example provides a method for refining quercetagetin, comprising the following steps: (1) Take 1 kg of quercetagetin crude extract, add 10 L of petroleum ether solvent, stir at 20°C for 6 h, filter to obtain a filter cake of quercetagetin, at this time the content of quercetagetin is 61.5%; (2) Add 15% methanol aqueous solution to the filter cake of quercetagetin in step (1), the solid-liquid ratio is 1 kg: 15 L, stir at 70°C for 12 h, and then filter to obtain a filter cake of quercetagetin (the water content of the filter cake is less than 50%), at this time the dry basis content of quercetagetin is 81.6%; (3) Add 90% methanol aqueous solution to the filter cake of quercetagetin in step (2), the solid-liquid ratio is 1 kg: 20 L, stir at 50°C for 6 h, and then filter to obtain a supernatant; (4) Add 12 L of pure water to the supernatant of step (3) at a flow rate of 300 mL / min, stir while adding, and then stand at room temperature for 2 h, filter to obtain a filter cake of quercetagetin, at this time the dry basis content of quercetagetin is 98.0%. It is calculated that the yield of quercetagetin is 96.0%.

[0055] Comparative Example 1 The present comparative example provides a method for refining quercetagetin, comprising the following steps: (1) Take 1 kg of quercetagetin crude extract, add 10 L of petroleum ether solvent, stir at 20°C for 6 h, filter to obtain a filter cake of quercetagetin, at this time the content of quercetagetin is 61.5%; (2) Add 15% methanol aqueous solution to the filter cake of quercetagetin in step (1), the solid-liquid ratio is 1 kg: 15 L, stir at 70°C for 12 h, and then filter to obtain a filter cake of quercetagetin (the water content of the filter cake is less than 50%), at this time the dry basis content of quercetagetin is 81.6%; (3) Add 90% methanol aqueous solution to the filter cake of quercetagetin in step (2), the solid-liquid ratio is 1 kg: 20 L, stir at 50°C for 6 h, and then filter to obtain a supernatant; (4) Directly add 16 L of pure water to the supernatant of step (3) at one time, stir and mix uniformly, then stand at room temperature for 2 h, filter to obtain a filter cake of quercetagetin, at this time the dry basis content of quercetagetin is 90.8%. It is calculated that the yield of quercetagetin is 95.4%.

[0056] Comparative Example 2 The present comparative example provides a quercetagetin refining method, which comprises the following steps: (1) Take 1 kg of quercetagetin crude extract, add 10 L of petroleum ether solvent, stir at 20°C for 6 h, filter to obtain a filter cake of quercetagetin, at this time the content of quercetagetin is 61.5%; (2) Add 15% methanol aqueous solution to the filter cake of quercetagetin in step (1), the solid-liquid ratio is 1 kg: 15 L, stir at 70°C for 12 h, and then filter to obtain a filter cake of quercetagetin (the water content of the filter cake is less than 50%), at this time the dry basis content of quercetagetin is 81.6%; (3) Add 90% methanol aqueous solution to the filter cake of quercetagetin in step (2), the solid-liquid ratio is 1 kg: 20 L, stir at 50°C for 6 h, and then filter to obtain a supernatant; (4) Add 40 L of pure water to the supernatant of step (3) at a flow rate of 500 mL / min, while stirring, stand at room temperature for 2 h, filter to obtain a filter cake of quercetagetin, at this time the dry basis content of quercetagetin is 90.4%. It is calculated that the yield of quercetagetin is 98.3%.

[0057] Comparative Example 3 The present comparative example provides a quercetagetin refining method, which comprises the following steps: (1) Take 1 kg of quercetagetin crude extract, add 10 L of petroleum ether solvent, stir at 20°C for 6 h, filter to obtain a filter cake of quercetagetin, at this time the content of quercetagetin is 61.5%; (2) Add 15% methanol aqueous solution to the filter cake of quercetagetin in step (1), the solid-liquid ratio is 1 kg: 15 L, stir at 70°C for 12 h, and then filter to obtain a filter cake of quercetagetin (the water content of the filter cake is less than 50%), at this time the dry basis content of quercetagetin is 81.6%; (3) Add 50% methanol aqueous solution to the filter cake of quercetagetin in step (2), the solid-liquid ratio is 1 kg: 36 L, stir at 50°C for 6 h, filter to obtain a filter cake of quercetagetin, at this time the dry basis content of quercetagetin is 88.5%. It is calculated that the yield of quercetagetin is 97.9%.

[0058] Comparative Example 4 This comparative example provides a method for refining quercetagetin, which comprises the following steps: (1) Take 1 kg of quercetagetin crude extract, add 4 L of n-hexane solvent, stir at 40°C for 4 h, filter to obtain a filter cake of quercetagetin, at this time the content of quercetagetin is 61.9%.

[0059] (2) Add 10% methanol aqueous solution to the filter cake of quercetagetin in step (1), the solid-liquid ratio is 1 kg: 10 L, stir at 60°C for 8 h, and then filter to obtain a filter cake of quercetagetin (the water content of the filter cake is less than 50%), at this time the dry basis content of quercetagetin is 76.3%; (3) Add 95% acetone aqueous solution to the filter cake of quercetagetin in step (2), the solid-liquid ratio is 1 kg: 20 L, stir at 50°C for 8 h, filter to obtain a supernatant; (4) Add 16 L of pure water to the supernatant of step (3) at a flow rate of 500 mL / min, stir while adding, and then stand at room temperature for 2 h, filter to obtain a filter cake of quercetagetin, at this time the dry basis content of quercetagetin is 87.9%. It is calculated that the yield of quercetagetin is 97.8%.

[0060] Comparative Example 5 This comparative example provides a method for refining quercetagetin, which comprises the following steps: (1) Take 1 kg of quercetagetin crude extract, add 30% methanol aqueous solution, the solid-liquid ratio is 1 kg: 10 L, stir at 60°C for 8 h, and then filter to obtain a filter cake of quercetagetin, at this time the dry basis content of quercetagetin is 67.4%; (2) To the filter cake of Echinacanthus in step (1), add 4L of n-hexane solvent, stir at 45℃ for 2h, filter, obtain the filter cake of Echinacanthus, at this time the content of Echinacanthus is 72.8%.

[0061] (3) To the filter cake of Echinacanthus in step (2), add 92% methanol aqueous solution, the ratio of material to liquid is 1kg:20L, stir at 50℃ for 8h, filter, obtain the supernatant; (4) To the supernatant of step (3), add 16L of pure water at the flow rate of 500mL / min, add while stirring, stir at room temperature for 2h, filter, obtain the filter cake of Echinacanthus, at this time the dry basis content of Echinacanthus is 85.4%. By calculation, the yield of Echinacanthus is 95.6%.

[0062] Finally, it should be noted that: the above examples are used to illustrate the technical solutions of the present application, but not limited to; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement to part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for refining quercetin, characterized in that, The method includes: sequentially subjecting the crude extract of marigold extract to a first washing and a second washing process, followed by a dissolution process and a precipitation separation process; The first impurity washing process uses a non-polar organic solvent for impurity washing, and the non-polar organic solvent includes at least one selected from n-hexane, petroleum ether, and cyclohexane. The second impurity washing process uses an aqueous solution of a polar organic solvent for impurity washing. The volume fraction of the polar organic solvent in the aqueous solution is 15%-35%, and the polar organic solvent includes at least one selected from methanol, ethanol, propanol, and acetone. The dissolution process involves dissolving quercetin in a polar organic solvent or its aqueous solution, and then separating the supernatant. The precipitation separation process involves mixing the supernatant with water, separating the solids, and collecting the solids. The water mixing process involves slowly adding water to the supernatant, with the amount of water added such that the volume fraction of the polar organic solvent used in the dissolution process in the system is 45%-65%, and the slow water addition is for a time of not less than 20 minutes.

2. The refining method according to claim 1, characterized in that, The crude extract of marigoldin is obtained from marigold flower pomace after extracting lutein or its esters, or it is the crude extract of marigoldin obtained when extracting marigoldin alone from marigold flowers. The extraction is carried out using a polar organic solvent or an aqueous solution thereof.

3. The refining method according to claim 1 or 2, characterized in that, The slow water addition refers to a water addition time controlled between 20-120 minutes; preferably 20-80 minutes. And / or, the amount of water added is such that the volume fraction of the polar organic solvent in the system is 45%-58%.

4. The refining method according to any one of claims 1 to 3, characterized in that, After adding water, let it stand for 1-3 hours, and then collect the solids after separation.

5. The refining method according to any one of claims 1 to 4, characterized in that, In the dissolution process, the polar organic solvent includes at least one selected from methanol, ethanol, propanol, and acetone; preferably methanol and / or acetone.

6. The refining method according to claim 5, characterized in that, The dissolution process involves dissolving the solvent in an aqueous solution of a polar organic solvent, wherein the volume fraction of the polar organic solvent in the aqueous solution is greater than 85%; more preferably 85%-99%.

7. The refining method according to claim 5 or 6, characterized in that, The material-to-liquid ratio for the dissolution treatment is 1 kg: 10-100 L, and / or the temperature is 30-60℃, and / or the treatment time is 6-12 h.

8. The refining method according to any one of claims 1 to 7, characterized in that, In the second washing and impurity treatment, the polar organic solvent is methanol and / or acetone.

9. The refining method according to any one of claims 1 to 8, characterized in that, The temperature of the first washing process is 20-45℃, and / or the washing time is 2-6h, and / or the material-to-liquid ratio is 1kg:4-10L; And / or, the temperature of the second washing treatment is 50-70℃, and / or, the washing time is 6-12h, and / or, the material-to-liquid ratio is 1kg:5-15L.

10. The quercetin prepared by the refining method according to any one of claims 1 to 9.

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