A method for preparing high purity tara tannin

Abstract

The application discloses a preparation method of high-purity Tara tannin, which comprises the following steps: (1) Tara powder is soaked in an acetone aqueous solution to obtain a soaking liquid, and then acetone in the soaking liquid is removed; (2) the material obtained in the step (1) is fully mixed with anhydrous ethanol, and then is placed at 0-4 DEG C and centrifuged to obtain a supernatant, and then ethanol in the supernatant is removed; (3) the material obtained in the step (2) is dissolved in methanol, and then is separated and purified through a chromatographic column, and then is eluted with an eluent to collect a tannin component, and then the eluent is removed, and the high-purity Tara tannin is obtained. The application is convenient and fast, the obtained Tara tannin is high in purity, technical support is provided for further utilization of the Tara tannin, and has important practical significance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of natural product purification, and particularly relates to a preparation method of high-purity tara tannin. BACKGROUND

[0002] Tannin, also known as tannin, is a kind of natural polyphenol compound with a molecular weight of 500-3000, which widely exists in the roots, bark, leaves and fruits of plants, and is one of the secondary metabolites of plants. As an important representative of natural polyphenols, tannin has many biological activities, such as antioxidant, antibacterial, antiviral, anticancer and the like. In addition, tannin can also be used in leather making, feed additive, food additive and the like. Due to its rich resources and wide application prospect, tannin has become one of the important objects of comprehensive utilization of forest resources. At present, the tannin tara tannin on the market mainly includes gallnut tannin, tara tannin and chestnut tannin.

[0003] Tara is a legume plant distributed in the northwest of South America, which is an important raw material for extracting plant tannin. With the soaring price of domestic gallnut in recent years, many manufacturers have turned to importing tara powder to produce tara tannin to replace gallnut tannin, or to prepare tara tannin and its derivatives. Tara tannin is the main component in tara powder, which belongs to hydrolyzed gallnut tannin, and its chemical structural formula is polygalloyl quinic acid. It can be hydrolyzed into quinic acid and gallic acid under the catalysis of acid, alkali or enzyme.

[0004] At present, the main extraction method of tara tannin is separation and purification from tara powder, but there is still no unified tara tannin extraction industry standard and national standard. Since tara tannin is a high-value chemical product and its source is relatively single, whether tara tannin can be efficiently extracted is a prerequisite for the development of tara plantation industry. SUMMARY

[0005] The present application aims to overcome the defects of the prior art, and provides a preparation method of high-purity tara tannin.

[0006] The technical scheme of the present application is as follows:

[0007] A preparation method of high-purity tara tannin, characterized in that it comprises the following steps:

[0008] (1) tara powder is extracted with acetone aqueous solution, and the extraction is repeated for 3-5 times to obtain an extraction liquid, and then the acetone in the extraction liquid is removed;

[0009] (2) the material obtained in step (1) is fully mixed with anhydrous ethanol, and then is placed at 0-4 DEG C and centrifuged to obtain a supernatant, and then the ethanol in the supernatant is removed;

[0010] (3) the material obtained in step (2) is dissolved in methanol, then separated and purified by a chromatographic column, then eluted with an eluent to collect a tannin component, and then the eluent is removed, to obtain the tannin.

[0011] In a preferred embodiment of the present application, in step (1), the concentration of the aqueous acetone solution is 50-70%, and the ratio of the tal powder to the aqueous acetone solution is 1:2-5.

[0012] Further preferably, in step (1), the aqueous acetone solution is subjected to ultrasonic-assisted extraction, heating-assisted extraction or microwave-assisted extraction during the extraction.

[0013] Further preferably, in step (1), the acetone in the extraction solution is removed by 28-32°C reduced-pressure distillation.

[0014] In a preferred embodiment of the present application, in step (2), after the material obtained in step (1) is mixed with anhydrous ethanol, the concentration of the ethanol is 80-90%.

[0015] Further preferably, in step (2), the centrifugation is performed at a speed of 4800-5200 rpm for 8-12 min.

[0016] Further preferably, in step (2), the ethanol in the supernatant is removed by 38-42°C reduced-pressure distillation.

[0017] In a preferred embodiment of the present application, in step (3), after the material obtained in step (2) is mixed with methanol, the concentration of the methanol is 45-53%.

[0018] Further preferably, in step (3), the chromatographic column is Sephadx LH-20, and the eluent is 70% aqueous acetone.

[0019] Further preferably, in step (3), the eluent is an aqueous acetone solution.

[0020] The present application has the advantages that it is convenient and fast, the obtained tannin has high purity (95-99%), provides technical support for further use of tannin, and has important practical significance. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The figure is a high-performance liquid chromatography detection result of the tannin obtained in Example 1 of the present application.

[0022] Figure 2 The figure is a high-performance liquid chromatography detection result of the tannin obtained in Example 2 of the present application.

[0023] Figure 3 The high performance liquid chromatography detection result diagram of the tara tannin obtained in the embodiment 3 of the application.

[0024] Figure 4 The infrared spectrum diagram of the tara tannin in the embodiment 4 of the application. DETAILED DESCRIPTION

[0025] The technical solutions of the application are further described and explained in the following specific embodiments combined with the drawings.

[0026] Embodiments 1-3

[0027] (1) The tara powder (200 mesh) is mixed with the 70% concentration acetone aqueous solution to perform ultrasonic assisted extraction for 30 min, and the extraction liquid is obtained, which is repeated for 3 times, and then the acetone in the extraction liquid is removed by 30°C reduced pressure distillation, and the solid-liquid ratio of the tara powder and the acetone aqueous solution is 1:3;

[0028] (2) The material obtained in the step (1) is mixed with anhydrous ethanol to reach 90% of the ethanol concentration, and then the supernatant is obtained by 4°C standing for 12 h and 5000 rpm centrifugation for 10 min, and then the ethanol in the supernatant is removed by 40°C reduced pressure distillation;

[0029] (3) The material obtained in the step (2) is dissolved with methanol to reach 50% of the methanol concentration, and then the Sephadx LH-20 chromatographic column is used for separation and purification, the 70% acetone-water solution is used as the eluent to elute and collect the tannin component, and then the acetone is removed by 30°C reduced pressure distillation, and finally the freeze-drying is performed to remove the water, and the tara tannin is obtained.

[0030] The difference between the embodiments 1-3 is that the tara powder in the embodiment 1 is 10.5 g, the tara powder in the embodiment 2 is 5.5 g, and the tara powder in the embodiment 3 is 8.3 g,

[0031] Correspondingly, the purity of the tara tannin obtained in the embodiment 1 is 95%, the purity of the tara tannin obtained in the embodiment 2 is 98%, and the purity of the tara tannin obtained in the embodiment 3 is 99%, and the high performance liquid chromatography detection results are shown in the following Figures 1 to 3

[0032] ​The high performance liquid chromatography detection is specifically: using high performance liquid chromatography area normalization method to determine the purity of tara tannin. Mobile phase A: using a graduated cylinder to take 1000 mL of ultrapure water, adding 1 mL of trifluoroacetic acid, and filtering through a 0.45 μm filter membrane; mobile phase B: methanol (chromatographically pure). Chromatographic column: BDS C18 4.6*250mm 5 μm chromatographic column; detector: UV detector; detection wavelength: 280 nm; column temperature: 30 DEG C; flow rate: 1.0 mL / min; injection volume: 10 μL; running time: 60 min; mobile phase: 0-3 min 10% B, 3-25 min 10%-30% B, 25-50 min 30%-80% B, 50-55 min 80%-10% B, 55-60 min 10% B.

[0033] Example 4

[0034] The infrared (IR) spectrum of the tara tannin prepared in Example 3 is shown in Figure 4 The absorption peak of the sample at 3458 cm -1 is mainly derived from the stretching vibration of hydroxyl, and the difference in hydrogen bonding system and the degree of association of hydroxyl causes the absorption peak to shift, so the peak shape is relatively wide; due to the high content of benzene ring in the sample, the absorption peak of aromatic hydrocarbon C-H stretching vibration appears at 3069 cm -1 ; the absorption peak at 2967 cm -1 is mainly derived from the symmetric / asymmetric stretching vibration of methylene; the absorption peak of the sample at 1734 cm -1 is related to the C=O stretching vibration in ester group structure; the absorption peaks at 1624 cm -1 , 1527 cm -1 and 1448 cm -1 are mainly derived from the C=C structure of the benzene ring skeleton, which is a typical feature of aromatic polymers; the absorption peaks at 1362 cm -1 and 1249 cm -1 are derived from the asymmetric stretching vibration of C-O, and the sample contains a large amount of oxygen-containing groups, including various C-O structures such as phenolic hydroxyl on the benzene ring, which will cause obvious absorption at the above two wave bands, so the peak shape of the two absorption peaks is relatively wide; the absorption peaks at 1087 cm -1 and 1042 cm -1 are derived from the stretching vibration of C-O and C-OH; but the absorption peak at 877 cm -1 is mainly derived from the out-of-plane bending vibration of C-H, and the absorption peak at 763 cm -1 is the stretching vibration peak of ortho-dihydroxy substitution on the benzene ring. The infrared spectrum data of the tara tannin in the literature (Liu J. Preparation process of tara tannin and ellagic acid [D]. Beijing University of Chemical Technology, 2012) is consistent, and it can be determined that the sample prepared by the application is tara tannin.

[0035] The above description is only the preferred embodiment of the present application, and cannot limit the scope of the present application. Any equivalent changes and modifications made according to the patent scope and content of the present application should still be within the scope of the present application.

Claims

1. A method for preparing high-purity taratanine, characterized in that: Includes the following steps: (1) Extract the tara powder with an acetone aqueous solution, repeating the process 3-5 times to obtain an extract. Then remove the acetone from the extract. The concentration of the acetone aqueous solution is 50-70%, and the ratio of tara powder to acetone aqueous solution is 1:2-5. (2) After thoroughly mixing the material obtained in step (1) with anhydrous ethanol, let it stand at 0-4℃ and centrifuge to obtain the supernatant, and then remove the ethanol from the supernatant; wherein the concentration of ethanol after mixing the material obtained in step (1) with anhydrous ethanol is 80-90%; (3) Dissolve the material obtained in step (2) in methanol, then separate and purify it by chromatographic column, then elute with eluent to collect tannin components, and then remove the eluent to obtain the product; wherein the concentration of methanol is 45-53% after mixing the material obtained in step (2), the chromatographic column is Sephadex LH-20, and the eluent used is 70% acetone-water solution.

2. The preparation method according to claim 1, characterized in that: In step (1), during the extraction with acetone aqueous solution, ultrasonic-assisted extraction, heating-assisted extraction, or microwave-assisted extraction are performed.

3. The preparation method according to claim 2, characterized in that: In step (1), acetone is removed from the extract by vacuum distillation at 30-40°C.

4. The preparation method according to claim 1, characterized in that: In step (2), the centrifugation speed is 4800-5200 rpm and the time is 8-12 min.

5. The preparation method according to claim 4, characterized in that: In step (2), the ethanol in the supernatant is removed by vacuum distillation at 40-50℃.

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