CN107382943A - A kind of method of dihydroquercetin in Subcritical Water Extraction sorghum bran - Google Patents

Abstract

The invention discloses a method for subcritical water extraction of dihydroquercetin in sorghum bran, belonging to the technical field of natural product chemistry. The method uses sorghum bran as a raw material, undergoes subcritical water extraction, suction filtration, vacuum concentration, low temperature standing, centrifugation, separation/enrichment, elution, distillate liquid standing at low temperature, crystallization and recrystallization, and drying. , to obtain pure dihydroquercetin. The method of the invention can be used for the industrialized production of high-purity dihydroquercetin, the sorghum bran raw material used is cheap and easy to obtain, the process flow is simple, the operation is simple, the cost is low, and there is no poisonous and harmful reagent pollution, and it can be used as a medical raw material.

Description

A method for extracting dihydroquercetin in sorghum bran with subcritical water

technical field

The invention belongs to the technical field of natural product chemistry, and in particular relates to a method for extracting dihydroquercetin from sorghum bran with subcritical water.

Background technique

Subcritical water, also known as superheated water, high-pressure hot water or hot liquid water, refers to heating water to a high temperature above 100°C and below the critical temperature of 374°C under a certain pressure, and the water remains in a liquid state. In the subcritical state, the hydrogen bond, ion hydration, ion association, cluster structure, etc. of the fluid microstructure have changed, so the properties of subcritical water and water at normal temperature and pressure are quite different. In the subcritical state, as the temperature rises, the polarity of water can change in a wide range, and the polarity of water can gradually change from strong polarity to non-polarity. Its properties are more similar to organic solvents, and solutes can be separated Extracted from high to low polarity. Subcritical water extraction technology has become the most eye-catching technology in the fields of food, chemical industry, and Chinese herbal medicine development, and has been rapidly applied to the preparation of food additives and functional factors and the recycling and recycling of food processing waste.

Dihydroquercetin is also called taxifolin and taxifolin. ,3',4'-pentahydroxyflavanone, the molecular formula is C ₁₅ H ₁₂ O ₇ , and the molecular weight is 304.26. Dihydroquercetin is one of the active ingredients of natural flavonoids, which belongs to the vitamin PP family and has strong antioxidant capacity. It can effectively eliminate excess free radicals from the human body, promote the permeability of capillaries, improve immune function, and reduce the formation of cancer; it is an excellent natural medicine for preventing cardiovascular diseases, effectively restoring the elasticity of capillaries, and preventing inflammation and tumor formation . At the same time, dihydroquercetin is also a high-efficiency natural food antioxidant, and its antioxidant effect exceeds other antioxidants such as quercetin, rutin and synthetic antioxidants. Dihydroquercetin is widely found in pinaceae plants, such as maritime pine, larch, and Douglas fir, and is the flavonoid compound with the largest content in larch, but the content of dihydroquercetin in plants is low, generally only 0.3 ~5.7%, these factors make dihydroquercetin more expensive, which further hinders its industrial production and application.

Sorghum is one of the main crops in the northern and southwestern regions of my country. It is mainly used for wine making and feed industry, and a small part is used as miscellaneous grains. Sorghum bran accounts for about 12% of sorghum grain mass. It contains a large amount of proanthocyanidins, anthocyanins, tannins, phenols, sterols, etc., and has high antioxidant capacity. Therefore, sorghum bran also has anti-cancer and anti-cancer effects. Previous studies have found that sorghum bran contains dihydroquercetin components, but there are no literature reports and patent applications for dihydroquercetin extraction and separation from sorghum bran. The invention can further expand the development and utilization of sorghum bran, and at the same time provide new resources and new methods for the extraction of dihydroquercetin, which can produce good social benefits and considerable economic benefits.

Contents of the invention

The purpose of the present invention is to provide a method for extracting dihydroquercetin from sorghum bran by subcritical water extraction technology.

The present invention is achieved through the following technical solutions:

A method for subcritical water extraction of dihydroquercetin in sorghum bran, carried out according to the following steps:

(1) Sorghum bran is used as raw material, dried and crushed through a 20-200 mesh sieve;

(2) The raw material is placed in an extraction kettle, and the sorghum bran powder is extracted with subcritical water. After suction filtration, the filter residue is repeatedly extracted three times, and the extracts are combined, concentrated under reduced pressure to a liquid extract;

(3) Preliminarily separate the macroporous adsorption resin chromatographic column on the extract described in step 2. After loading the sample, first elute with distilled water to remove unadsorbed water-soluble impurities, and then elute with a certain volume fraction of ethanol aqueous solution, Collect effective distillates;

(4) Concentrate the above-mentioned effective distillate under reduced pressure until it has no alcohol smell, and place it under low temperature conditions to precipitate a crystalline crude product; the crude product is recrystallized and vacuum-dried to obtain pure dihydroquercetin.

In step (2), the dosage ratio of the sorghum bran to water is 1g:10-50mL; the extraction is carried out in subcritical extraction equipment, the extraction temperature is 100-200°C, the extraction time is 8-60min, and the pressure 4 ~ 10MPa.

In step (3), the macroporous adsorption resin is non-polar or medium polar, and the specific models are D101, AB-8 and ADS-17, etc.; in the ethanol aqueous solution of a certain volume, the volume fraction of ethanol is 30 ~95%; the effective distillate is the dihydroquercetin-containing dihydroquercetin distillate detected by HPLC.

In step (4), the low temperature condition is 0-4°C; the specific steps of the recrystallization are: dissolving the crude product of dihydroquercetin in hot water, suctioning and filtering while it is hot, stirring and cooling, and placing in 0 Recrystallization at -4°C was repeated three times to obtain dihydroquercetin.

Beneficial effects of the present invention: the subcritical water extraction method of dihydroquercetin in sorghum bran disclosed by the present invention, the extraction solvent and sorghum bran raw materials used are cheap and easy to obtain, the process flow involved is simple, the operation is simple, and it involves The cost of the chemical agent is relatively low, it can be recycled and reused, there is no pollution by toxic and harmful reagents, it can be industrialized, and it can be used as a raw material for medicine.

Description of drawings

Fig. 1 is the HPLC graph of dihydroquercetin monomer compound isolated from sorghum bran.

detailed description

The experimental methods described in the following examples, unless otherwise specified, are conventional methods; the reagents and materials, unless otherwise specified, can be obtained from commercial sources.

Example 1

Take 100g of sorghum bran powder that has been crushed through a 20-mesh sieve, put it in a subcritical water extraction kettle, add 1000mL of water, control the extraction pressure to 4MPa, the extraction temperature to 100°C, and the extraction time to 8min. Filtration, the filter residue was repeatedly extracted three times, the combined filtrate was concentrated under vacuum and reduced pressure; the concentrated solution was loaded on a macroporous resin chromatographic column (AB-8 macroporous adsorption resin, non-polar, glass column model Φ3.0* at a flow rate of 3 mL/min) (1100cm), with the same flow rate, wash the column with 2000mL distilled water; Adopt the ethanol aqueous solution elution of 30% by volume fraction, collect dihydroquercetin effective distillate liquid, detect with high performance liquid chromatography (method sees embodiment 3); Concentrate the collected effective fractions under reduced pressure until there is no alcohol smell, let stand at 0°C, precipitate crystals and filter to obtain the crude product of dihydroquercetin; dissolve the crude product of dihydroquercetin in hot water, and Hot suction filtration, stirring and cooling, the filtrate was left standing at 0°C, recrystallized, and vacuum-dried at room temperature to obtain pure dihydroquercetin. As detected by HPLC, the purity of dihydroquercetin was higher than 97.68%, and the extraction rate was 85.3%.

Example 2

Take 100g of sorghum bran powder that has been crushed through a 200-mesh sieve, put it in a subcritical water extraction kettle, add 5000mL of water, control the extraction pressure to 10MPa, the extraction temperature to 200°C, and the extraction time to 60min. Filtration, the filter residue was repeatedly extracted three times, the combined filtrate was concentrated under reduced pressure in vacuo; the concentrated solution was applied to a macroporous resin chromatographic column (ADS-17 macroporous adsorption resin, non-polar, glass column model Φ3.0* at a flow rate of 3 mL/min) (1100cm), with the same flow rate, rinse the column with 2000mL distilled water; adopt the ethanol aqueous solution elution of 95% by volume fraction, collect dihydroquercetin effective distillate liquid, detect with high performance liquid chromatography (method sees embodiment 3); Concentrate the collected effective fractions under reduced pressure until there is no alcohol smell, let stand at 4°C, precipitate crystals and filter to obtain crude dihydroquercetin; dissolve the crude dihydroquercetin in hot water, and Hot suction filtration, stirring and cooling, the filtrate was left standing at 4°C, recrystallized, and vacuum-dried at room temperature to obtain pure dihydroquercetin. As detected by HPLC, the purity of dihydroquercetin is higher than 95.44%, and the extraction rate is 91.7%.

Example 3

This embodiment is an embodiment of the detection method of dihydroquercetin.

Dihydroquercetin is detected by high-performance liquid chromatography, and the dihydroquercetin product is 290nm in the detection wavelength, and is separated through Agilent ZORBAX SB-C18 column (4.6 * 250mm, 5 μ m) (mobile phase: A phase is 0.1% Acetic acid aqueous solution, phase B is methanol; flow rate is 1mL/min, column temperature is 25°C, gradient elution), the chromatogram is shown in Figure 1, the chromatographic peak of dihydroquercetin appears at 25.45min, under the same chromatographic conditions Below, the retention time of this peak is consistent with the retention time of kaempferrin reference substance.

Claims (6)

1. a kind of method of dihydroquercetin in Subcritical Water Extraction sorghum bran, it is characterised in that carry out as steps described below：

（1）Using sorghum bran as raw material, crushed after being dried crosses 20 ~ 200 mesh sieves；

（2）Raw material is placed in extraction kettle, and sorghum bran powder is extracted with subcritical water, and after suction filtration, filter residue is repeated Extraction three times, merges extract solution, is concentrated under reduced pressure into liquid extract；

（3）By macroporous adsorption resin chromatography post carries out initial gross separation on medicinal extract described in step 2, after loading, first with distillation water elution Unadsorbed water-solubility impurity is removed, then is eluted with the ethanol water of certain volume fraction, collects effective cut liquid；

（4）Above-mentioned effectively cut liquid is concentrated under reduced pressure into no alcohol taste, is placed under cryogenic conditions, it is separated out crystallization crude product；Slightly Product obtains dihydroquercetin sterling after recrystallizing, being dried in vacuo again.

2. the method for dihydroquercetin, its feature exist in a kind of Subcritical Water Extraction sorghum bran according to claim 1 In step（2）In, the amount ratio of the sorghum bran and water is 1g:10~50mL.

3. the method for dihydroquercetin, its feature exist in a kind of Subcritical Water Extraction sorghum bran according to claim 1 In step（2）In, the extraction is carried out in subcritical abstraction equipment, extraction temperature be 100 ~ 200 DEG C, extraction time be 8 ~ 60min, pressure are 4 ~ 10MPa.

4. the method for dihydroquercetin, its feature exist in a kind of Subcritical Water Extraction sorghum bran according to claim 1 In step（3）In, the macroporous absorbent resin is nonpolar or middle polarity resin, the ethanol water of the certain volume In, the volume fraction of ethanol is 30 ~ 95%.

5. the method for dihydroquercetin, its feature exist in a kind of Subcritical Water Extraction sorghum bran according to claim 4 In the macroporous absorbent resin be D101, AB-8 and ADS-17.

6. the method for dihydroquercetin, its feature exist in a kind of Subcritical Water Extraction sorghum bran according to claim 4 In step（4）In, the cryogenic conditions are 0 ~ 4 DEG C；The recrystallization concretely comprises the following steps：By dihydroquercetin crude product, use Hot water dissolving, filter, stirring cooling, recrystallized under the conditions of being put in 0-4 DEG C, repeated crystallization three times, obtains dihydroquercetin while hot.