CN114890972B - Method for preparing demethyl nobiletin by degrading nobiletin by microwave synergistic deep co-dissolution reagent - Google Patents

Method for preparing demethyl nobiletin by degrading nobiletin by microwave synergistic deep co-dissolution reagent Download PDF

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CN114890972B
CN114890972B CN202210588689.9A CN202210588689A CN114890972B CN 114890972 B CN114890972 B CN 114890972B CN 202210588689 A CN202210588689 A CN 202210588689A CN 114890972 B CN114890972 B CN 114890972B
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nobiletin
deep
reagent
demethyl
degrading
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CN114890972A (en
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曾新安
湛瑾璟
蔡锦林
韩忠
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Guangzhou Paihu Technology Co ltd
South China University of Technology SCUT
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Guangzhou Paihu Technology Co ltd
South China University of Technology SCUT
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    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07DHETEROCYCLIC COMPOUNDS
    • C07D311/00Heterocyclic compounds containing six-membered rings having one oxygen atom as the only hetero atom, condensed with other rings
    • C07D311/02Heterocyclic compounds containing six-membered rings having one oxygen atom as the only hetero atom, condensed with other rings ortho- or peri-condensed with carbocyclic rings or ring systems
    • C07D311/04Benzo[b]pyrans, not hydrogenated in the carbocyclic ring
    • C07D311/22Benzo[b]pyrans, not hydrogenated in the carbocyclic ring with oxygen or sulfur atoms directly attached in position 4
    • C07D311/26Benzo[b]pyrans, not hydrogenated in the carbocyclic ring with oxygen or sulfur atoms directly attached in position 4 with aromatic rings attached in position 2 or 3
    • C07D311/28Benzo[b]pyrans, not hydrogenated in the carbocyclic ring with oxygen or sulfur atoms directly attached in position 4 with aromatic rings attached in position 2 or 3 with aromatic rings attached in position 2 only
    • C07D311/30Benzo[b]pyrans, not hydrogenated in the carbocyclic ring with oxygen or sulfur atoms directly attached in position 4 with aromatic rings attached in position 2 or 3 with aromatic rings attached in position 2 only not hydrogenated in the hetero ring, e.g. flavones

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  • Organic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

The invention provides a method for preparing demethyl nobiletin by degrading nobiletin through microwave synergistic deep co-dissolution reagent, and belongs to the technical field of preparation of demethyl nobiletin. The deep co-solvent reagent formed by the choline chloride and the oxalic acid has the dual functions of an organic solvent and an acidic reagent. The oxygen atoms of the 5-methoxyl group and the C-cyclocarbonyl group of the nobiletin have isolated oxygen atom pairs, and under the strong acid environment formed by the deep co-solvent reagent, a six-membered ring structure coordinated by proton-hydrogen and electron-donor-oxygen is easily formed, and the six-membered ring can be continuously hydrolyzed to become hydroxyl, so that the nobiletin is converted into the demethyl nobiletin after the 5-methoxyl group is removed. The invention utilizes microwaves to degrade, is convenient for hydrogen ions to attack the nobiletin, and thus prepares out the methyl nobiletin in a short time. Compared with the traditional acidolysis method, the method has high conversion efficiency and can control the reaction time to be about 20 minutes.

Description

Method for preparing demethyl nobiletin by degrading nobiletin by microwave synergistic deep co-dissolution reagent
Technical Field
The invention relates to the technical field of preparation of demethyl nobiletin, in particular to a method for preparing demethyl nobiletin by degrading nobiletin by using a microwave synergistic deep co-dissolution reagent.
Background
The demethyl nobiletin is a flavonoid, and has more powerful active functions than nobiletin, such as antioxidant, antiinflammatory, anticancer cell proliferation, anti-neurodegenerative disease and liver fibrosis preventing effects. However, the conversion rate of the dehydromethylation of the nobiletin under natural conditions is very low, and the use of the dehydromethylation of the nobiletin in functional foods and medicines is greatly limited due to the influence of factors such as storage temperature, humidity, microbial distribution and the like.
At present, the method for preparing the demethyl nobiletin by degrading the nobiletin is mainly an acidolysis method. Luo Shikun et al found that nornobiletin (Luo Shikun, wang Guhuan, xu Lanying, long Tao, & Li Shiming. Extraction and modification of nobiletin in pericarpium Citri Tangerinae. Food science, 2014 (24), 20-23.); chu et al prepared desmethyl nobiletin (Chu H W, wu H T, lee Y J. Regional electric hydrolysis of 2-hydroxychalcones by dimethyldioxirane towards polymethoxylated flavonoids, 2004,60 (11): 2647-2655) from boron tribromide, boron trichloride, aluminum trichloride and concentrated hydrochloric acid. However, hydrochloric acid is a volatile acid, which is poor in operability, and the use of hydrochloric acid and organic reagents easily corrodes production equipment, producing non-degradable acidic waste liquid to pollute the environment, and is disadvantageous for industrial production. Huang et al replace the highly corrosive acids with edible acids such as phosphoric acid, lactic acid and citric acid, but require high temperature conditions at 175 ℃ for conversion (Huang X, kouX, wang L, et al effective hydroxylation oftangeretin from Citrus Peel (Chenpi) by edible acids and its improvement in antioxidant and anti-liveactivity.lwt, 2019, 116:108469.) and this method requires a long high temperature heating process, is energy consuming and is less costly and safer. Therefore, an efficient, energy-saving and environment-friendly method for degrading nobiletin to prepare demethyl nobiletin is urgently needed.
Disclosure of Invention
The invention aims to provide a method for preparing demethyl nobiletin by degrading nobiletin by using a microwave synergistic deep co-dissolution reagent, which realizes high efficiency, green and environment protection, and does not generate organic and acidic waste liquid in the process.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a method for preparing demethyl nobiletin by degrading nobiletin with a microwave synergistic deep-dissolution reagent, which comprises the following steps:
mixing nobiletin and a deep co-solvent reagent, degrading the obtained mixture under the microwave condition, and separating to obtain the demethylated nobiletin; the deep co-solvent reagent is choline chloride and oxalic acid.
Preferably, the molar ratio of the choline chloride to the oxalic acid is 1:1.
Preferably, the concentration of the nobiletin in the deep-cosolvent reagent is 1-2 mg/mL.
Preferably, the power of the microwaves is 750-850W, and the temperature is 100-105 ℃.
Preferably, the degradation time is 15-20 min.
Preferably, the separation comprises mixing degradation products obtained by degradation with water, followed by refrigeration and centrifugation.
Preferably, the volume ratio of the water to the deep-eutectic agent is (10-12): 1.
Preferably, the temperature of the refrigeration is 4 ℃ and the time is 3-5 hours.
Preferably, after the separation, the method further comprises the step of performing rotary evaporation on the obtained liquid to obtain the deep co-solvent reagent.
Preferably, the temperature of the rotary steaming is 45 ℃.
The invention provides a method for preparing demethyl nobiletin by degrading nobiletin with a microwave synergistic deep-dissolution reagent, which comprises the following steps: and mixing the nobiletin and the deep co-solvent reagent, degrading the obtained mixture under the microwave condition, and separating to obtain the demethyl nobiletin. The deep co-solvent reagent formed by the choline chloride and the oxalic acid has the solubility of an organic solvent, and the concentration of hydrogen ions is higher than that of strong acids such as hydrochloric acid, sulfuric acid and the like, so that the deep co-solvent reagent has the dual functions of the organic solvent and the acidic reagent. The oxygen atoms of the 5-methoxyl group and the C-cyclocarbonyl group of the nobiletin have isolated oxygen atom pairs, and under the strong acid environment formed by the deep co-solvent reagent, a six-membered ring structure coordinated by proton-hydrogen and electron-donor-oxygen is easily formed, and the six-membered ring can be continuously hydrolyzed to become hydroxyl, so that the nobiletin is converted into the demethyl nobiletin after the 5-methoxyl group is removed. The invention utilizes microwaves to degrade, the penetrability of microwave energy can rapidly and uniformly heat reactants, and the porosity of the reactants is improved, so that the whole reaction system can be heated to about 100 ℃ in a short time, the probability of collision of polar molecules in the system is increased, meanwhile, the acting force among molecules in the system is enhanced, and hydrogen ions can attack the nobiletin conveniently, so that the methyl nobiletin can be prepared in a short time. Compared with the traditional acidolysis method, the method has high conversion efficiency and can control the reaction time to be about 20 minutes.
The deep eutectic agent used in the invention is a new generation of ionic liquid formed by hydrogen bond donors and hydrogen bond acceptors, and has the excellent properties of low cost, low toxicity, biodegradability and the like.
Compared with the traditional acidolysis method, the method for preparing the demethyl nobiletin by degrading the nobiletin by utilizing the microwave synergistic deep-dissolution reagent does not need long-time high-temperature heating treatment, is safe in operation and low in energy consumption cost, does not need to use organic solvents such as ethanol and the like, does not need to use strong corrosive inorganic acids such as concentrated hydrochloric acid and the like, does not need to use organic solvents, and the used deep-dissolution reagent can be recycled after separation, so that no acid and organic waste liquid are generated in the whole process, the method is green and environment-friendly, and provides guidance for preparing other demethyl polymethoxy flavones such as the demethyl nobiletin.
Furthermore, the invention utilizes water to separate out the methyl-Sichuan citrinin, and the water is not only an acceptor of hydrogen bonds but also a donor of hydrogen bonds, so that the stability of the deep-eutectic reagent is damaged by the addition of the water to reduce the solubility of the deep-eutectic reagent, the water solubility of the demethyl-Sichuan citrinin is poorer, precipitate can be separated out under the condition that the system stability is damaged, and after the precipitated demethyl-Sichuan citrinin is collected, the solution is distilled off to remove the water, and the deep-eutectic reagent can be recycled, so that no acid waste liquid is generated in the whole reaction process.
Drawings
FIG. 1 is a liquid chromatogram of standard substances of nobiletin and demethyl nobiletin;
FIG. 2 is a liquid chromatogram of nobiletin and desmethyl nobiletin in example 1;
FIG. 3 is a liquid chromatogram of nobiletin and desmethyl nobiletin in example 2;
FIG. 4 is a liquid chromatogram of nobiletin and desmethyl nobiletin in example 3;
FIG. 5 is a liquid chromatogram of nobiletin and desmethyl nobiletin in comparative example 1.
Detailed Description
The invention provides a method for preparing demethyl nobiletin by degrading nobiletin with a microwave synergistic deep-dissolution reagent, which comprises the following steps:
mixing nobiletin and a deep co-solvent reagent, degrading the obtained mixture under the microwave condition, and separating to obtain the demethylated nobiletin; the deep-solubilizing agent preferably comprises choline chloride and oxalic acid.
In the present invention, the preparation materials are commercially available as known to those skilled in the art unless otherwise specified.
The invention mixes the nobiletin and the deep-dissolving reagent. The source of the nobiletin is not particularly limited, and the nobiletin can be commercially available products well known in the art.
In the invention, the deep-dissolution reagent is choline chloride and oxalic acid; the molar ratio of the choline chloride to the oxalic acid is preferably 1:1; the preparation method of the deep-dissolution reagent preferably comprises the steps of mixing choline chloride and oxalic acid, and placing the mixture in a water bath at the temperature of 100 ℃ for stirring until a clear and transparent deep-dissolution reagent is formed; the stirring rate is not particularly limited in the present invention, and the materials can be uniformly mixed according to a process well known in the art.
In the invention, the concentration of the nobiletin in the deep-cosolvent reagent is preferably 1-2 mg/mL.
The process of mixing the nobiletin and the deep-dissolving reagent is not particularly limited, and the materials are uniformly mixed according to the process well known in the art.
After the mixing is completed, the obtained mixture is degraded under the microwave condition. In the invention, the power of the microwaves is preferably 750-850W, more preferably 800W, and the temperature is preferably 100-105 ℃ and more preferably 102 ℃; the degradation time is preferably 15 to 20min, more preferably 17min.
In the invention, the microwave digestion instrument used for microwaves is preferably a MARS 6240/50 type microwave digestion instrument of CEM company in America.
After the degradation is completed, the obtained product is separated; the separation preferably comprises mixing degradation products obtained by degradation with water, and sequentially refrigerating and centrifuging; the water is preferably ultrapure water; the volume ratio of water to the deep-solubilizing agent is preferably (10-12): 1, more preferably 11:1. The process of mixing the degradation product with water is not particularly limited in the present invention, and may be carried out according to a process well known in the art. The invention uses ultrapure water to separate out the demethyl nobiletin.
In the present invention, the temperature of the refrigeration is preferably 4℃and the time is preferably 3 to 5 hours.
The process of the centrifugal separation is not particularly limited, and may be performed according to a process well known in the art.
After the centrifugal separation is completed, the obtained precipitate is preferably washed to be neutral by ultrapure water and then freeze-dried to obtain the demethyl nobiletin. The washing and freeze-drying processes are not particularly limited in the present invention, and may be performed according to processes well known in the art.
After the centrifugal separation is completed, the method preferably further comprises the step of carrying out rotary evaporation on the obtained liquid, and collecting high-viscosity components to obtain the deep co-solvent reagent. In the present invention, the temperature of the rotary evaporation is preferably 45 ℃. The invention removes water in the liquid by rotary evaporation; the time of the spin-steaming is not particularly limited, and all the water in the liquid may be removed.
The technical solutions of the present invention will be clearly and completely described in the following in connection with the embodiments of the present invention. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the following examples, the microwave apparatus used was a MARS 6240/50 microwave digestion instrument from CEM company, USA.
Example 1
Mixing choline chloride and oxalic acid according to a molar ratio of 1:1, and placing the mixture in a water bath at 100 ℃ for stirring until a clear and transparent deep-dissolution reagent is formed;
dissolving 20mg of nobiletin pure product in 20mL of prepared deep co-dissolution reagent, uniformly mixing, putting the obtained mixture into a microwave digestion instrument, wherein the treatment condition is that the microwave power is 750W, the microwave temperature is 100 ℃, and the treatment time is 15min, so as to obtain degradation products;
adding 10 times of volume of ultrapure water to the degradation product, refrigerating the obtained mixture at 4 ℃ for 5 hours, centrifuging, washing the obtained precipitate with the ultrapure water to be neutral, and freeze-drying to obtain the demethyl nobiletin.
Example 2
Mixing choline chloride and oxalic acid according to a molar ratio of 1:1, and placing the mixture in a water bath at 100 ℃ for stirring until a clear and transparent deep-dissolution reagent is formed;
dissolving 40mg of nobiletin pure product in 20mL of prepared deep co-dissolution reagent, uniformly mixing, putting the obtained mixture into a microwave digestion instrument, wherein the treatment condition is that the microwave power is 800W, the microwave temperature is 102 ℃, and the treatment time is 17min, so as to obtain degradation products;
adding 11 times of volume of ultrapure water to the degradation product, refrigerating the obtained mixture at 4 ℃ for 5 times, centrifuging, washing the obtained precipitate with the ultrapure water to be neutral, and freeze-drying to obtain the demethyl nobiletin.
Example 3
Mixing choline chloride and oxalic acid according to a molar ratio of 1:1, and placing the mixture in a water bath at 100 ℃ for stirring until a clear and transparent deep-dissolution reagent is formed;
dissolving 20mg of nobiletin pure product in 20mL of prepared deep co-dissolution reagent, uniformly mixing, putting the obtained mixture into a microwave digestion instrument, wherein the treatment condition is that the microwave power is 800W, the microwave temperature is 105 ℃, and the treatment time is 20min, so as to obtain degradation products;
adding 12 times of volume of ultrapure water to the degradation product, refrigerating the obtained mixture at 4 ℃ for 5 times, centrifuging, washing the obtained precipitate with the ultrapure water to be neutral, and freeze-drying to obtain the demethyl nobiletin.
Comparative example 1
Traditional acidolysis method: catalyzing 20mg of nobiletin in 20mL of concentrated hydrochloric acid with the mass percentage of 37% for 12h, and keeping the reaction temperature at 90 ℃ all the time to obtain degradation products.
Result detection
1) Mixing 1mg of nobiletin standard substance and 1mg of demethyl nobiletin standard substance in 1mL of methanol, taking the obtained mixed solution as a standard sample, taking 500 mu L of the standard sample, and performing high performance liquid chromatography detection, wherein the high performance liquid chromatography detection process comprises the following steps:
sucking 500 mu L of sample, adding 500 mu L of chromatographic grade methanol, uniformly mixing, and passing through a 0.45 mu m nylon membrane for later use;
the detection equipment is Agilent 1260 Infinicity high performance liquid chromatograph, the chromatographic column model is Waters Atlantis T column (2.1X105 mm,1 μm), mobile phase A is glacial acetic acid of 0.1% (v/v), mobile phase B is acetonitrile, and the flow rate is 0.8mL/min;
the elution procedure was as follows: 0-2 min, 5-5% B; 2-10 min, 5-30% B; 10-12 min, 30-100% B; 12-18 min, 100-100% B; 18-20 min, 100-5% B; 20.00-25.00 min, 5-5%;
the column temperature is kept at 25 ℃, and the ultraviolet detection wavelength is 210nm; the results obtained are shown in FIG. 1; FIG. 1 is a chromatogram of a nobiletin standard and a nornobiletin standard; the peak time of nobiletin and desmethyl nobiletin is evident in FIG. 1.
2) The conversion of nobiletin and the production of desmethyl nobiletin in examples 1-3 were examined by high performance liquid chromatography as described in 1): the results obtained by taking the nobiletin-deep co-solvent reagent mixture and the deep co-solvent reagent mixed solution (namely degradation product) of the nobiletin after degradation in examples 1-3 as detection samples are shown in figures 2-4; meanwhile, the degradation product of comparative example 1 is subjected to high performance liquid chromatography detection, the obtained result is shown in fig. 5, and the result is analyzed as follows:
as shown in FIG. 2, in example 1, the nobiletin was almost completely converted into the desmethyl nobiletin, the conversion rate was 99.62%, and the treatment time was 15min, with high efficiency. As shown in FIG. 3, in example 2, almost all of the nobiletin was converted into desmethyl nobiletin, the conversion rate was 99.57%, and the treatment time was 17min, with high efficiency. As shown in FIG. 4, in example 3, almost all of the nobiletin was converted into desmethyl nobiletin, the conversion rate was 99.65%, and the treatment time was 20min, with high efficiency. Whereas comparative example 1 was reacted for 12 hours using the conventional acidolysis method, the conversion rate reached only 23.52%, demonstrating that the process of the present invention can significantly reduce the treatment time and increase the conversion rate.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.

Claims (8)

1. A method for preparing demethyl nobiletin by degrading nobiletin with microwave synergistic deep-dissolution reagent comprises the following steps:
mixing nobiletin and a deep co-solvent reagent, degrading the obtained mixture under the microwave condition, and separating to obtain the demethylated nobiletin; the deep co-dissolution reagent is choline chloride and oxalic acid; the power of the microwaves is 750-850W, and the temperature is 100-105 ℃; the degradation time is 15-20 min.
2. The method according to claim 1, wherein the molar ratio of choline chloride to oxalic acid is 1:1.
3. the method according to claim 1, wherein the concentration of nobiletin in the deep-solubilizing reagent is 1-2 mg/mL.
4. The method of claim 1, wherein the separating comprises mixing degradation products from the degradation with water, and sequentially refrigerating and centrifuging.
5. The method of claim 4, wherein the volume ratio of water to deep co-solvent agent is (10-12): 1.
6. the method of claim 4, wherein the temperature of the refrigeration is 4 ℃ for 3 to 5 hours.
7. The method of claim 1, further comprising subjecting the resulting liquid to spin evaporation to provide a deep-eutectic reagent after the separating.
8. The method of claim 7, wherein the temperature of the rotary evaporation is 45 ℃.
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