阅读说明：本技术 一种制备木犀草素的方法 (Method for preparing luteolin ) 是由 张琦 李振伟 韩魁元 李冬玲 于 2018-11-09 设计创作，主要内容包括：一种制备木犀草素的方法,包括：将芦丁充分溶解于pH≥10的碱性溶液中；加入芦丁投料量5~24当量的由二氧化硫脲、氯化钾和碳酸钾组成的还原剂,搅拌至溶液澄清；控制在60~90℃的温度下反应1~2小时,即得木犀草素。该方法工艺简单、成本低廉、反应条件温和、耗时短、收率高,适用于工业化生产。(A process for preparing luteolin, comprising: fully dissolving rutin in an alkaline solution with the pH value of more than or equal to 10; adding a reducing agent which is composed of thiourea dioxide, potassium chloride and potassium carbonate and accounts for 5-24 equivalents of rutin, and stirring until the solution is clear; and controlling the temperature to be 60-90 ℃ for reacting for 1-2 hours to obtain the luteolin. The method has the advantages of simple process, low cost, mild reaction conditions, short time consumption and high yield, and is suitable for industrial production.)

1. A process for the preparation of luteolin, the process comprising the steps of:

1) fully dissolving rutin in an alkaline solution with the pH value of more than or equal to 10;

2) adding a reducing agent which is composed of thiourea dioxide, potassium chloride and potassium carbonate and accounts for 5-24 equivalents of rutin, and stirring until the solution is clear;

3) and controlling the temperature to be 60-90 ℃ for reacting for 1-2 hours to obtain the luteolin.

2. A process for the preparation of luteolin according to claim 1, wherein: the alkaline solution is a sodium hydroxide solution, a potassium hydroxide solution, a lithium hydroxide solution or a sodium carbonate solution.

3. A process for the preparation of luteolin according to claim 1, wherein: the dosage of the alkaline solution is 30-35 times of the mass of rutin.

4. A process for the preparation of luteolin according to claim 1, wherein: the dissolving process of the step 1) is carried out at the temperature of 45-90 ℃.

5. A process for the preparation of luteolin according to claim 1, wherein: the mass ratio of the components in the reducing agent in the step 2) is 30-45: 50-70: 1-5.

6. A process for the preparation of luteolin according to claim 1, wherein: the reaction temperature in the step 3) is 80-85 ℃.

7. A process for producing luteolin according to claim 1, characterized in that the process further comprises the step of isolating and purifying the obtained luteolin as follows:

4) after the reaction is finished, cooling the solution to below 25 ℃, adjusting the pH value to 1-6, and stirring to separate out a solid;

5) and after the solid is separated out, filtering the solution, collecting a filter cake, leaching the filter cake with water, and drying the filter cake to obtain the luteolin crude product.

8. A process for the preparation of luteolin according to claim 7, wherein: in the step 4), the temperature of the solution is reduced to 10-20 ℃.

9. A process for the preparation of luteolin according to claim 7, wherein: in the step 4), the pH value is adjusted to 2-3.

10. A process for the preparation of luteolin according to claim 7, wherein: the method also comprises the following step of refining the obtained luteolin crude product:

6) fully dissolving the luteolin crude product into anhydrous monohydric alcohol containing carbon number of C1-C5 at the temperature of 45-70 ℃;

7) cooling to 10-25 ℃, and waiting for solid precipitation;

8) and after the solid is separated out, filtering the solution, collecting a filter cake, leaching the filter cake by using 50% volume concentration aqueous solution containing monohydric alcohol with carbon number of C1-C5, and drying the filter cake to obtain the luteolin refined product.

11. A process for the preparation of luteolin according to claim 10, wherein: the monohydric alcohol with the carbon number of C1-C5 is methanol.

12. A process for the preparation of luteolin according to claim 10, wherein: and in the step 7), standing for 0.5-2 hours is carried out in the process of waiting for the solid to be separated out.

Technical Field

The invention relates to the technical field of synthesis of pharmaceutical and chemical products, in particular to a semisynthetic method for preparing luteolin.

Background

Luteolin is a natural flavonoid compound, is named after being separated from leaves, stems and branches of luteolin of herb of luteolin family, is widely distributed in nature, and can be separated from various natural medicinal materials and vegetables and fruits. Luteolin has various pharmacological activities such as anti-inflammation, anti-allergy, uric acid reduction, anti-tumor, antibacterial and antivirus, and is mainly used for relieving cough, eliminating phlegm, diminishing inflammation, reducing uric acid, and treating amyotrophic lateral sclerosis, SARS, hepatitis, cardiovascular diseases and the like.

The commonly used preparation methods of luteolin known at present include plant extraction and separation methods and chemical synthesis methods. For example, chinese patent CN105646424B discloses a method for separating and extracting high-purity luteolin from natural medicinal materials or extracts thereof containing luteolin, such as perilla leaf, honeysuckle flower, etc., which comprises the steps of leaching, decocting, concentrating, centrifuging, recovering solvent, microfiltration, preparing liquid phase separation, drying, etc., and has the disadvantages of tedious process, low extraction rate, long time consumption and high cost. The chemical synthesis method is divided into a total synthesis method and a semi-synthesis method, such as luyuhua and the like, and discloses a total synthesis method of luteolin, which takes phloroglucinol as a raw material, prepares 2,4, 6-trihydroxyacetophenone according to a Hoesch method, protects 4, 6-dihydroxy with methyl, condenses with isovanillin to generate corresponding chalcone, takes 6 days, and prepares the luteolin after selenium dioxide oxidation and hydroiodic acid demethylation, and the method has long time consumption and low total yield which is only 3-4%. The semisynthetic method mostly uses hesperidin or rutin as raw materials to prepare luteolin, for example, Chinese patent application CN103145670A discloses a new process for semisynthetic preparation of luteolin by using hesperidin as raw materials, which comprises the steps of hydrolyzing hesperidin into hesperetin, demethylating the hesperetin to convert the hesperetin into eriodictyol, dehydrogenating the eriodictyol to convert the eriodictyol into luteolin, and finally crystallizing, centrifuging and drying to obtain the fine luteolin with the yield of 40.2%; also, for example, chinese patent CN102002028B discloses a semisynthetic preparation method of luteolin from rutin, which comprises dissolving rutin in alkaline water, adding sodium hydrosulfite (sodium hydrosulfite), reacting at 100 ℃ for 12h for hydrolysis reduction, and recrystallizing at pH 3-4 to obtain luteolin with a yield of only 56.5%, wherein the reaction conditions of the method are harsh and difficult to control industrially due to unstable properties of sodium hydrosulfite.

Disclosure of Invention

In view of the defects in the background art, the invention aims to solve the technical problems of complicated process, long time consumption, low yield and high cost of the existing method for preparing luteolin, and provides a semisynthetic method for preparing luteolin, which has the advantages of simple process, low cost, mild reaction conditions, high efficiency and high yield.

To achieve the above object, the inventors conducted extensive experimental investigations for a long time and finally developed a novel method for producing luteolin, the method comprising: 1) fully dissolving rutin in an alkaline solution with the pH value of more than or equal to 10; 2) adding a reducing agent which is composed of thiourea dioxide, potassium chloride and potassium carbonate and accounts for 5-24 equivalents of rutin, and stirring until the solution is clear; 3) and controlling the temperature to be 60-90 ℃ for reacting for 1-2 hours to obtain the luteolin.

Rutin (Rutin), alias Rutin, vitamin P, purple quercitrin, Lonicera Japonica fructus, LUTONG, LUDING powder, fructus Lipuidambaris, LUTONG and ZIPI glycoside etc., can be used as edible antioxidant and nutrition enhancer, has vitamin P-like effect and antiinflammatory effect, and has molecular formula of C₂₇H₃₀O₁₆The CAS number is 153-18-4, and the character is light yellow or light green needle crystal or crystalline powder.

Preferably, the alkaline solution in step 1) of the process of the invention is a sodium hydroxide solution, a potassium hydroxide solution, a lithium hydroxide solution or a sodium carbonate solution.

More preferably, the dosage of the alkaline solution in the step 1) of the method is 30-35 times of the mass of the rutin.

In order to accelerate the dissolution and shorten the time, the dissolution process in step 1) of the method is preferably controlled to be carried out at a temperature of 45-90 ℃. More preferably, the dissolving process in step 1) of the method is controlled to be carried out at a temperature of 60-90 ℃.

The ratio of the components in the reducing agent used in step 2) of the method is preferably (30-45) of thiourea dioxide, potassium chloride and potassium carbonate, (50-70) and (1-5) according to the mass ratio.

In the step 3) of the method, the reaction temperature of 60-90 ℃ is favorable for accelerating the reaction speed and improving the conversion rate, and simultaneously the total duration of the whole process is controlled in a more reasonable range. If the reaction temperature is too high, more impurities are generated, and the time for later-stage cooling is too long; if the reaction temperature is too low, the conversion rate is low. More preferably, the reaction temperature in step 3) of the method is 80-85 ℃.

In order to make the reaction process more mild, smooth and controllable, the heating process of step 1) and step 3) of the method of the invention is preferably carried out in a water bath environment.

Further, the method also comprises the following steps of separating and purifying the luteolin generated by the reaction:

4) after the reaction is finished, cooling the solution to below 25 ℃, adjusting the pH value to 1-6, and stirring to separate out a solid; 5) and after the solid is separated out, filtering the solution, collecting a filter cake, leaching the filter cake with water, and drying the filter cake to obtain the luteolin crude product.

In the step 4) of the method, the temperature of the solution is reduced, so that the problem that the yield is influenced by overhigh temperature rise due to heat release in the subsequent pH value adjusting process is avoided, the time required by temperature reduction and the heat release amount are comprehensively considered, and the temperature of the solution is preferably reduced to 10-20 ℃.

In step 4) of the method of the present invention, it is preferable to adjust the pH to 2 to 3 in order to maximize the amount of precipitated solids.

Preferably, hydrochloric acid, sulfuric acid or phosphoric acid is used for adjusting the pH value in step 4), and more preferably, hydrochloric acid is used for adjusting the pH value, and the concentration of the hydrochloric acid is 6-8M. Compared with sulfuric acid or phosphoric acid, hydrochloric acid has the advantages of low price, low risk, high speed of neutralizing alkali liquor, shortened reaction process and no influence on the stability of the product; the concentration of 6-8M is favorable for improving the product yield, further accelerating the reaction speed and simultaneously reducing the generation of byproducts, and in addition, the concentration releases heat slowly, so that the adverse effect caused by high temperature can be avoided.

Preferably, the volume of water for leaching the filter cake in the step 5) of the method is 10-30 times of the mass of rutin.

Further, the method also comprises the following step of refining the obtained luteolin crude product:

6) fully dissolving a luteolin crude product in anhydrous monohydric alcohol containing carbon number of C1-C5 at 45-70 ℃; 7) cooling to 10-25 ℃, and waiting for solid precipitation; 8) and after the solid is separated out, filtering the solution, collecting a filter cake, leaching the filter cake by using 50% volume concentration aqueous solution containing monohydric alcohol with carbon number of C1-C5, and drying the filter cake to obtain the luteolin refined product.

The temperature of 45-70 ℃ in the step 6) of the method can ensure that impurities and luteolin in the luteolin crude product are dissolved to the maximum extent.

Preferably, the volume of the anhydrous monohydric alcohol with the carbon number of C1-C5 in the step 6) of the method is 5-20 times of the mass of the crude luteolin.

In order to accelerate the sufficient dissolution speed of the luteolin crude product and the anhydrous monohydric alcohol containing carbon number of C1-C5, the dissolution process of the step 6) of the method is preferably carried out under stirring, and the stirring time is preferably 0.5-2 hours.

The dissolution process of step 6) of the process of the invention is preferably carried out in a water bath environment.

The reason why the temperature is reduced to 10-25 ℃ in step 7) of the method is that: within the temperature range, luteolin can be precipitated from the solution in a solid form to the maximum extent, and impurities can not be precipitated or are precipitated in a very small amount.

Preferably, the process of waiting for the solids to precipitate in step 7) of the process of the invention is: standing for 0.5-2 hours.

Preferably, the volume of the water solution containing the monohydric alcohol with the carbon number of C1-C5 for leaching the filter cake in the step 8) of the method is 1-5 times of the mass of the crude luteolin.

In the step 6) and the step 8) of the method, the monohydric alcohol with the carbon number of C1-C5 is methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol or pentanol; preferably methanol, has the advantages of small using amount, low cost and capability of improving the yield and the content of the product.

Preferably, the drying treatment in step 5) and step 8) of the method is vacuum drying, and more preferably, the drying temperature is 50-80 ℃.

In order to further increase the purity of the luteolin product, it is preferred to repeat the refining steps of step 6) to step 8) of the method of the present invention.

Sufficient dissolution in the process of the invention means that the solute is dissolved in a solvent so that the solution is saturated.

The filtration in the method of the invention refers to a process of separating solid and liquid in a solution by adopting a physical method, and common filtration methods are all applicable to the method of the invention, including normal pressure filtration, reduced pressure filtration, centrifugal filtration and the like.

Has the advantages that:

compared with the prior art, the method has the advantages of simple process, low cost, short time consumption and high yield, compared with the semisynthesis method which takes rutin as a raw material and is disclosed in Chinese patent CN102002028B, the process conditions of the method are much milder, for example, the reaction temperature is reduced from 100 ℃ to 60-90 ℃, the reaction time is reduced from 12 hours to 1-2 hours, but simultaneously, the conversion rate of the method is improved from 70% to more than 90%, the purity of a crude product is 87% -95%, the content is 72% -88%, and the molar yield can reach more than 91%, and the refined product with further improved purity and content can be obtained through a simple refining process, so that the production cost is greatly reduced, and the method is more suitable for industrial production.

Detailed Description

The present invention will be described in further detail with reference to specific examples, which are illustrative of the present invention and are not to be construed as being limited thereto.

The raw materials and reagents used in the following examples were all commercially available except for those specifically mentioned. Sodium hydrosulfite (sodium hydrosulfite) used in the following examples was purchased from Shanghai Aladdin Biotechnology Ltd under the batch number LD 1826075; the reducing agent used in the following examples is self-made, and the mass ratio of the components is thiourea dioxide, potassium chloride and potassium carbonate is 9: 10: 1.

The following examples were all prepared according to the following process steps, wherein the homemade reducing agent was added in step 3) of examples 1 to 7, the sodium hydrosulfite was added in step 3) of comparative examples 1 and 2, and the experimental results are shown in table 1, wherein: t1 denotes the dissolution temperature in step 2) and T2 denotes the reaction temperature in step 4).

1) Preparing a sodium hydroxide aqueous solution: weighing 8.1kg of sodium hydroxide, dissolving in 300L of water, and stirring until the solution is clear to obtain a sodium hydroxide aqueous solution;

2) weighing 10.0kg of rutin, adding into the prepared sodium hydroxide aqueous solution, heating in a water bath at 45-80 ℃, and stirring until the solution is clear;

3) adding 35.0kg of self-made reducing agent or sodium hydrosulfite into the solution, and stirring until the solution is clear;

4) keeping the solution at the temperature of 65-80 ℃ and continuing stirring for reaction, sampling every half hour for HPLC detection, and monitoring the residual amount of the raw material rutin;

5) finishing the reaction within 1-2 hours, then cooling the temperature of the reaction liquid to 10-20 ℃, dropwise adding 7M hydrochloric acid solution until the pH value of the reaction liquid is 2-3, and stirring to separate out a solid;

6) after stirring for 10 minutes, filtering the reaction solution, collecting a filter cake, leaching the filter cake with 200L of water, and then placing the filter cake at the temperature of 60 ℃ for vacuum drying until the LOD percent is less than or equal to 5 percent to obtain a luteolin crude product;

7) mixing the luteolin crude product prepared in the step 6) with methanol, wherein the volume of the methanol is 10 times of the mass of the luteolin crude product, and heating and stirring the mixture for 1 hour in a water bath at 65 ℃;

8) then cooling to 20 ℃, and standing for 1 hour;

9) filtering the solution, collecting filter cakes, leaching the filter cakes by using 50% methanol aqueous solution with the volume being 3 times of the mass of the filter cakes, and then placing the filter cakes at the temperature of 60 ℃ for vacuum drying until the LOD% is less than or equal to 5%, thus obtaining the luteolin refined product.

TABLE 1