Method and device for extracting stibene glucoside from polygonum multiflorum

Abstract

The invention belongs to the technical field of separation and extraction of natural products, and particularly relates to a method and a device for extracting stibene glucoside from polygonum multiflorum. The stilbene glucoside is one of main components of polygonaceae plant polygonum multiflorum, has various physiological activities and medicinal values, has effects in the aspects of reducing blood fat, resisting aging, inhibiting tumors and the like, and has important research, development and utilization values. According to the extraction method, polygonum multiflorum is usually used as a raw material, and high-content stibene glucoside is obtained through the processes of extraction, adsorption separation, crystallization and the like. However, the existing method for extracting stilbene glucoside from polygonum multiflorum generally has the problems of complex extraction process, low content of stilbene glucoside and the like. The invention discloses a method and a device for extracting stilbene glucoside from polygonum multiflorum, which are characterized in that an extraction process and an adsorption separation process are organically combined through a specially designed extraction device, so that the effect of the whole extraction process is improved, the technical process is simplified, and high-content stilbene glucoside is extracted from the polygonum multiflorum.

Description

Technical Field

[0001] The invention belongs to the technical field of separation and extraction of natural products, and particularly relates to a method and a device for extracting stilbene glycosides from Polygonum multiflorum. Background Art

[0002] Stilbene glycosides are a major component of the Polygonum multiflorum plant, also known as Polygonum multiflorum. They possess numerous physiological activities and medicinal properties, demonstrating efficacy in lowering blood lipids, combating aging, and inhibiting tumors, making them valuable for research, development, and utilization. Extraction methods typically use Polygonum multiflorum as a raw material, and then proceed through extraction, adsorption separation, and crystallization to yield high levels of stilbene glycosides. However, existing methods for extracting stilbene glycosides from Polygonum multiflorum generally suffer from complex extraction processes and low stilbene glycoside content.

[0003] In 2013, CN 103087123A disclosed a method for extracting stilbene glycosides from Polygonum multiflorum. The extraction method comprises the following steps: 1) mixing Polygonum multiflorum powder with 0.5-3% of its mass in a base, then adding 8-10 times the mass of water to mix evenly to obtain a suspension of Polygonum multiflorum powder; 2) extracting the suspension under reflux and concentrating it to obtain a concentrate; 3) adding 3-5 times the mass of an organic solvent at a volume fraction of 90-95% to the concentrate, allowing precipitation to complete, filtering, and collecting the filtrate; 4) extracting the filtrate with ethyl acetate, collecting the aqueous phase, and allowing it to stand for complete crystallization, whereupon the crystals are collected to obtain stilbene glycosides. While the stilbene glycosides obtained by this preparation method have a purity exceeding 95%, the stilbene glycoside content is low.

[0004] In 2017, CN 107722079A disclosed a method for extracting stilbene glycosides from Polygonum multiflorum. The method comprises the following steps: 1) crushing Polygonum multiflorum and extracting it under reflux with ethanol to obtain an ethanol extract; 2) recovering the ethanol extract under reduced pressure to 40°C to obtain an extract with a relative density of 1.0 to 1.5. The extract is dissolved in water, filtered, and the filtrate is set aside; 3) applying the filtrate to S-8+ macroporous resin, eluting it first with distilled water and then with 50% ethanol, and collecting the ethanol eluate; 4) recovering the solvent from the ethanol eluate under reduced pressure and freeze-drying it to obtain stilbene glycosides with a purity exceeding 99%. This preparation method is complex.

[0005] In summary, the existing methods for extracting stilbene glycosides from Polygonum multiflorum generally have problems such as complex extraction process and low stilbene glycoside content. Summary of the Invention

[0006] The technical problem to be solved by the present invention is that the existing method for extracting stilbene glycosides from Polygonum multiflorum has the problems of complex extraction process and low stilbene glycoside content.

[0007] The technical solution adopted by the present invention: Specifically, the extraction method of the present invention comprises the following steps:

[0008] (1) Grind and sieve Polygonum multiflorum to form fine powder;

[0009] (2) placing the fine powder in an extraction column and extracting it with an extractant to form an extract;

[0010] (3) the extract is subjected to adsorption and desorption in an adsorption column to form a stilbene glycoside desorption solution;

[0011] (4) the diphenylethylene glycoside desorption solution is concentrated to form a concentrated solution;

[0012] (5) the concentrated solution is crystallized with isopropyl alcohol to form the fine product of diphenylethylene glycoside;

[0013] Wherein, the passing rate of the fine powder in step (1) on a 40-mesh sieve is 100%; the retention rate of the fine powder on a 100-mesh sieve is 100%; and the content of the diphenylethylene glycoside fine product in step (5) is ≥99.0%.

[0014] The present invention first crushes and sieves Polygonum multiflorum to form a fine powder. Unlike the crushing and sieving process in the prior art, the present invention requires strict control of the particle size of the Polygonum multiflorum fine powder, wherein the passing rate of the fine powder on a 40-mesh screen in step (1) is 100%; and the retention rate of the fine powder on a 100-mesh screen is 100%. The purpose of controlling the particle size of the fine powder is to ensure that the extractant flows through the fine powder layer in a plug flow manner during the subsequent extraction process, without the occurrence of uneven flow processes such as short-circuiting, channeling, and bypassing. Such uneven flow can cause abnormal fluctuations in the content of diphenyl glycosides in the extract at the outlet of the extraction column, which is not conducive to the extraction method of the present invention that combines extraction and adsorption separation. Then, the fine powder is placed in the extraction column and leached with the extractant to form an extract. The present invention performs the extraction operation in the extraction column. Unlike the existing kettle extraction process, the content of diphenyl glycosides in the extract at the outlet of the extraction column changes dynamically. The overall trend of stilbene glycoside content changes from low to high and then from high to low. This allows for an organic combination with adsorption separation, mutually reinforcing the effect and improving the overall extraction efficiency. During extraction in the extraction column, substances that are easily soluble in the extractant but poorly adsorbed by the Polygonum multiflorum powder preferentially exit the column, while substances that are less soluble in the extractant but easily adsorbed by the Polygonum multiflorum powder lag behind. This results in a concentration distribution of the various components in the Polygonum multiflorum at the column outlet. The extract then undergoes adsorption and desorption in the adsorption column to form a stilbene glycoside desorption solution. In the adsorption column, substances preferentially adsorbed by the adsorbent are retained in the adsorbent's micropores, while the remaining substances preferentially leave the adsorbent. Combining extraction with adsorption separation effectively combines the selectivity of the extraction process with the selectivity of the adsorption process, improving the overall extraction efficiency and achieving the goal of 1+1>2. Finally, the stilbene glycoside desorption solution is concentrated to form a concentrated solution. This concentrated solution is crystallized from isopropyl alcohol to form a refined stilbene glycoside solution, containing ≥99% stilbene glycoside. The adsorption process redistributes the components in the extract. Recalcitrant components quickly leave the adsorption column, leaving diphenylethylene glycosides adsorbed on the adsorbent surface and in its micropores. Desorption by a desorbent yields a high-content diphenylethylene glycoside desorbate. This high-content diphenylethylene glycoside desorbate is then concentrated to form a concentrate. This concentrate is then crystallized with isopropyl alcohol to produce a premium diphenylethylene glycoside concentrate with a content of ≥99.0%.

[0015] In a preferred technical solution, the aspect ratio of the fine powder in the extraction column in step (2) is 4 to 6:1; the temperature of the extraction process in step (2) is controlled to be 40 to 60°C; the extractant is an alcohol-water mixture; the mass ratio of alcohol to water in the alcohol-water mixture is 0.1 to 0.3:1; the alcohol is selected from at least one of methanol and ethanol. The temperature of the extraction process determines the quality and speed of the extraction. A high temperature leads to a fast extraction speed, resulting in less residual stilbene glycosides in the Polygonum multiflorum fine powder, but the stilbene glycosides are easily deteriorated; a low temperature leads to a slow extraction speed, resulting in more residual stilbene glycosides in the Polygonum multiflorum powder, but the stilbene glycosides are not easily deteriorated. The present invention uses an alcohol-water mixture at 40 to 60°C to extract the stilbene glycosides in the Polygonum multiflorum fine powder, and the extraction process is carried out in an extraction column, which has the characteristics of moderate extraction speed and high extract content. Compared with kettle extraction, extraction column extraction has the characteristics of large driving force and high extraction efficiency. The present invention requires strict control of the aspect ratio of the fine powder in the extraction column to be 4 to 6:1. Different from the existing extraction process, the extraction process described in the present invention is equivalent to the reverse process of adsorption separation, namely the desorption process. The Polygonum multiflorum fine powder is equivalent to the adsorbent. In order to desorb the diphenylethylene glycosides therein, the flow of the alcohol-water mixture in the Polygonum multiflorum fine powder must be controlled to be a plug flow. If abnormal flows such as short circuits, channeling, and bypassing occur, it will seriously affect the changing trend of the diphenylethylene glycoside content at the outlet of the extraction column, which is not conducive to combining extraction and adsorption separation. When the particle size of the Polygonum multiflorum fine powder is controlled to be between 40 and 100 mesh sieves, the Polygonum multiflorum fine powder layer has a larger bulk density, and it is not easy for abnormal flows such as short circuits, channeling, and bypassing to occur when the extractant penetrates the Polygonum multiflorum fine powder layer, and the extraction and adsorption combined separation process runs more smoothly.

[0016] In a preferred technical solution, the adsorbent used in the adsorption process of step (3) is a medium-polarity macroporous adsorption resin, and the mass ratio of the medium-polarity macroporous adsorption resin to the fine powder of step (2) is 1 to 5:1; the aspect ratio of the medium-polarity macroporous adsorption resin in the adsorption column is 4 to 6:1; and the temperature of the adsorption process in step (3) is controlled to be 20 to 40°C. The inventors have determined through comparison that the use of the medium-polarity macroporous adsorption resin can effectively selectively adsorb the extract whose content of diphenylethylene glycosides changes over time. At the same time, it is necessary to control the mass ratio of the medium-polarity macroporous adsorption resin to the fine powder of Polygonum multiflorum to be 1 to 5:1. Under this ratio condition, the amount of adsorbent used matches the mass of diphenylethylene glycosides in the Polygonum multiflorum powder, and the adsorption capacity of the adsorbent can be fully utilized without causing diphenylethylene glycoside loss. At the same time, it is necessary to control the aspect ratio of the medium-polarity macroporous adsorption resin in the adsorption column to be 4 to 6:1. Controlling this ratio is also to reduce the adverse effects of abnormal flow phenomena such as short-circuiting, channeling, and bypassing during the adsorption or desorption process on the separation effect.

[0017] In a further preferred technical solution, the intermediate polar macroporous adsorption resin is one of AB-8, HPD-450, XAD-7, and XAD-8. The present invention uses one of AB-8, HPD-450, XAD-7, and XAD-8 as the adsorption resin for the adsorption separation of stilbene glycosides. AB-8, HPD-450, XAD-7, and XAD-8 resins have suitable pore sizes and polarities, and can highly selectively adsorb stilbene glycosides, thereby separating stilbene glycosides from other components.

[0018] In a preferred technical solution, the desorbent used in the desorption process of step (3) is an alcohol-water mixture, wherein the mass ratio of alcohol to water in the alcohol-water mixture is 7 to 9:1, and the alcohol is selected from at least one of methanol or ethanol. The temperature of the desorption process in step (3) is controlled to be 5 to 20°C. The present invention uses the alcohol-water mixture as the desorbent, utilizing the high solubility of diphenylethylene glycoside in the alcohol-water mixture to desorb diphenylethylene glycoside adsorbed on the surface and micropores of the intermediate-polarity macroporous adsorption resin. The alcohol is selected from at least one of methanol or ethanol and has the characteristics of low price, low boiling point, and convenient recovery. During the desorption process, the mass ratio of alcohol to water in the alcohol-water mixture needs to be controlled to be 7 to 9:1. Under this ratio, the desorption rate is faster. The temperature of the desorption process is controlled to be 5 to 20°C. Under this temperature, the diphenylethylene glycoside adsorbed on the adsorption resin can be completely desorbed while reducing the amount of other components desorbed.

[0019] The present invention also discloses an apparatus for extracting diphenylethylene glycosides from Polygonum multiflorum, comprising an extraction column, a heat exchanger, and an adsorption column interconnected in sequence. Unlike the intermittent extraction and / or adsorption processes of the prior art, the present invention connects the extraction and adsorption processes via a pipeline and eliminates the need for a temporary storage device between the extraction and adsorption equipment. This approach offers the following advantages: 1. A complete continuous process is achieved, simplifying the operation process; 2. The dynamic extraction process and the dynamic adsorption separation process are combined, achieving mutual promotion and improving the overall extraction process.

[0020] In a preferred embodiment, the extraction column comprises a first cylindrical body, a first upper end cap, a first lower end cap, and a first support plate positioned at the bottom of the first cylindrical body. A first feed port is located at the center of the top of the first upper end cap, and a first discharge port is located on the side of the bottom of the first cylindrical body, located above the first support plate. A first inlet is located on the side of the upper portion of the first cylindrical body, extending through a pipe to the center of the first cylindrical body. A first outlet is located at the center of the bottom of the first lower end cap. The first cylindrical body and the first upper end cap can be flanged or welded, while the first cylindrical body and the first lower end cap need to be flanged to hold the first support plate. A filter medium, such as filter cloth or a sintered plate, is laid on the surface of the first support plate. A first feed port is located at the center of the top of the first upper end cap for feeding fine Polygonum multiflorum powder, and a first discharge port is located on the side of the bottom of the first cylindrical body, located above the first support plate. When extraction is complete, water can be added through the first feed port or the first inlet to flush the Polygonum multiflorum powder from the first cylindrical body through the first discharge port. A first inlet is provided on the upper side of the first cylindrical body, extending through a pipe to the center of the first cylindrical body. This first inlet serves as the inlet for the extractant, which enters the center of the Polygonum multiflorum powder layer. A preferred structure is one in which the extractant is evenly distributed to the upper end surface of the Polygonum multiflorum powder layer via a distributor, minimizing uneven flow of the extractant within the Polygonum multiflorum powder layer. A first outlet is provided at the center of the bottom of the first lower head. This first outlet, serving as the outlet for the extractant, is located at the center of the bottom of the lower head, eliminating the problem of liquid accumulation.

[0021] In the preferred technical solution, the adsorption column is composed of a second cylinder, a second upper head, a second lower head and a second support plate placed at the bottom of the second cylinder; a second feeding port is provided at the top center of the second upper head, and a second discharge port is provided on the bottom side of the second cylinder and located on the upper part of the second support plate; a second inlet is provided on the upper side of the second cylinder, and the second inlet extends to the center of the second cylinder through a pipe; a second outlet is provided at the bottom center of the second lower head. The second cylinder and the second upper head can be connected by flange or welding, and the second cylinder and the second lower head need to be connected by flange, which can be used to clamp the second support plate. The surface of the second support plate is paved with a filter medium, which can be a filter cloth or a sintered plate, and the sintered plate can be made of ceramic or metal; a second feeding port is provided at the top center of the second upper head for adding adsorption resin. A second discharge port is provided on the side of the bottom of the second cylinder and located on the upper part of the second support plate. When the adsorption and separation effect of the adsorption resin deteriorates, water can be added from the second feeding port or the second inlet to flush the adsorption resin inside the second cylinder out of the second discharge port; a second inlet is provided on the side of the upper part of the second cylinder, and the second inlet extends to the center of the second cylinder through a pipe; the second inlet, as the inlet of the leachate or desorbent, needs to be passed into the center of the adsorption resin layer. The preferred structure is that the leachate or desorbent is evenly distributed to the upper surface of the adsorption resin layer through the distributor, which can minimize the uneven flow of the leachate or desorbent in the adsorption resin layer; a second outlet is provided at the bottom center of the second lower head. The second outlet is set at the bottom center of the lower head as the outlet for the desorption liquid, and there is no problem of liquid accumulation.

[0022] In a preferred embodiment, the heat exchanger is provided with an inlet, an outlet, a heat exchange medium inlet, and a heat exchange medium outlet. Single-tube and single-shell shell-and-tube heat exchangers are preferred in this invention due to their simple structure and minimal liquid accumulation. Water is preferably used as the heat exchange medium, and its temperature can be rapidly adjusted to accommodate the varying temperature requirements for adsorption and desorption. The temperature of the water heat exchange medium requires control using separate heat exchange equipment.

[0023] In a preferred technical solution, the inlet of the heat exchanger and the first outlet of the extraction column are connected by a pipeline; the outlet of the heat exchanger and the second inlet of the adsorption column are also connected by a pipeline. The present invention directly connects the extraction column, heat exchanger, and adsorption column via pipelines, without any buffering equipment in between. Under the conditions of continuous flow during the extraction process, the selective adsorption of stilbene glycosides by extraction and adsorption is fully utilized to produce a high content of stilbene glycosides.

[0024] In summary, the present invention discloses a method and apparatus for extracting stilbene glycosides from Polygonum multiflorum. The combination of the extraction method and the extraction apparatus solves the problems of the prior art in terms of complex preparation process and low content of stilbene glycosides extracted. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Attachment Figure 1 The present invention is a schematic flow chart of a method and device for extracting stilbene glycosides from Polygonum multiflorum.

[0026] Among them: Mark 1-extraction column; Mark 11-first upper head; Mark 111-first feeding port; Mark 12-first cylinder; Mark 121-first inlet; Mark 122-first discharge port; Mark 13-first lower head; Mark 131-first outlet; Mark 14-first support plate; Mark 2-heat exchanger; Mark 21-inlet; Mark 22-outlet; Mark 23-heat exchange medium outlet; Mark 24-heat exchange medium inlet; Mark 3-adsorption column; Mark 31-second upper head; Mark 311-second feeding port; Mark 32-second cylinder; Mark 321-second inlet; Mark 322-second discharge port; Mark 33-second lower head; Mark 331-second outlet; Mark 34-second support plate; Mark 4-extraction agent; Mark 5-desorbent; Mark 6-sampling port. DETAILED DESCRIPTION

[0027] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0028] From the attached Figure 1 It can be seen that the extraction device of the present invention is composed of an extraction column 1, a heat exchanger 2 and an adsorption column 3 connected in sequence. The extraction column 1 is composed of a first cylinder 12, a first upper head 11, a first lower head 13 and a first support plate 14 placed at the bottom of the first cylinder 12. A first feeding port 111 is provided at the top center of the first upper head 11, and a first outlet 131 is provided at the bottom center of the first lower head 13. The first feeding port 111 is used as the feeding port for the Polygonum multiflorum fine powder and is provided at the top center of the first upper head 11, so that the Polygonum multiflorum fine powder can be more evenly fed into the interior of the first cylinder 12; the first outlet 131 is the outlet of the extract and is provided at the bottom center of the first lower head 13, so that there is no problem of liquid accumulation. The first inlet 121 is provided on the side of the upper part of the first cylinder 12, from which Figure 1 It can be clearly seen that the first inlet 121 is inserted into the center of the interior of the first cylinder 12 through a pipe, so that the extractant can evenly enter the upper part of the Polygonum multiflorum fine powder layer. The first inlet 121 is connected to the delivery pipe of the extractant 4, and the extractant 4 can be continuously delivered to the first inlet 121. A first discharge port 122 is provided on the side of the lower part of the first cylinder 12, and the Polygonum multiflorum fine powder after extraction leaves the first cylinder 12 through the first discharge port 122. The first support plate 14 is arranged inside the first cylinder 12 and at the lower part of the first cylinder 12. A filter medium is provided on the first support plate 14. The filter medium can be a filter cloth or a sintered plate. The first support plate 14 is used to support the filter medium and the Polygonum multiflorum fine powder.

[0029] The condenser is provided with an inlet 21, an outlet 22, a heat exchange medium inlet 24 and a heat exchange medium outlet 23. Its function is to heat or cool the material entering the heat exchanger from the inlet 21 to a set temperature through the heat exchange medium.

[0030] The adsorption column 3 described in the present application is composed of a second cylinder 32, a second upper head 31, a second lower head 33 and a second support plate 34 placed in the second cylinder 32. A second feed port 311 is provided at the top center of the second upper head 31, and a second outlet 331 is provided at the bottom center of the second lower head 33; the second feed port 311 is used as a feed port for the adsorbent and is provided at the top center of the second upper head 31, so that the adsorbent can be fed more evenly into the interior of the second cylinder 32; the second outlet 331 is the outlet for the leachate or desorption liquid after adsorption and is provided at the bottom center of the second lower head 33, so there is no problem of liquid accumulation. The second inlet 321 is provided on the side of the upper part of the second cylinder 32, and is connected to the second cylinder 32 from the attached Figure 1 It can be clearly seen that the second inlet 321 is inserted into the center of the second cylinder 32 through a pipe, so that the leachate or desorbent can evenly enter the upper part of the adsorbent layer. The second inlet 321 is connected to the delivery pipe of the desorbent 5, and the desorbent 5 can be continuously delivered to the second inlet 321. A sampling port 6 is also provided on the connecting pipe between the outlet 22 of the heat exchanger 2 and the second inlet 321 of the adsorption column 3, which is convenient for sampling to determine the extraction situation. A second discharge port 322 is provided on the lower side of the second cylinder 32, and the adsorbent that has been adsorbed and inactivated multiple times leaves the second cylinder 32 through the second discharge port 322. The second support plate 34 is arranged inside the second cylinder 32 and at the lower part of the first cylinder 32. A filter medium is provided on the second support plate 34. The filter medium can be a filter cloth or a sintered plate. The second support plate 34 is used to support the filter medium and the adsorbent.

[0031] Experimental equipment parameters used in the embodiment

[0032] Extraction column diameter: 16.5 cm;

[0033] Total height of extraction column: 120cm;

[0034] Adsorption column diameter: 18cm;

[0035] Total height of adsorption column: 150cm;

[0036] Example 1

[0037] Preparation: Take 220 kg of dried, blocky Polygonum multiflorum and grind it in a grinder. The ground Polygonum multiflorum powder is first sieved through a 70-mesh sieve. The retained Polygonum multiflorum is then added to the grinder and ground again until all of the Polygonum multiflorum powder passes through a 40-mesh sieve. The Polygonum multiflorum powder that passes through the 40-mesh sieve is sieved through a 100-mesh sieve, and the retained Polygonum multiflorum powder is removed for later use. The Polygonum multiflorum powder that passes through the 100-mesh sieve is concentrated and the diphenylethylene glycosides are extracted using conventional methods. The final product is 205 kg of Polygonum multiflorum fine powder, containing 1.121% diphenylethylene glycosides.

[0038] Loading the extraction column: Slowly add 12.5 kg of Polygonum multiflorum powder from the first feeding port of the extraction column. Gently tap the outer wall of the extraction column while adding the powder to ensure that there are no voids in the Polygonum multiflorum powder layer in the extraction column. The aspect ratio of the Polygonum multiflorum powder layer in the extraction column is 4.2. After the Polygonum multiflorum powder is added, add 3-5 cm thick quartz sand to cover the Polygonum multiflorum powder layer. This will prevent the impact of the extractant on the Polygonum multiflorum powder layer from damaging the structure and allow the extractant to evenly penetrate the Polygonum multiflorum powder layer.

[0039] Loading the adsorption column: Add 35 kg of water to the adsorption column. Slowly add 27.5 kg of XAD-7 macroporous adsorption resin from the second feed port of the adsorption column. Continuously release a small amount of water from the outlet during the resin addition process to ensure that the upper end of the resin layer is immersed in water. The aspect ratio of the adsorption resin layer in the adsorption column is 5.7. After the resin is added, add 3 to 5 cm of quartz sand to cover the upper part of the resin layer.

[0040] Cooling water at 25°C was continuously introduced into the heat exchanger in advance.

[0041] Extraction and adsorption: Prepare a 0.2:1 ethanol:water mixture and preheat to 50°C. Pump the mixture into the first inlet of the extraction column via a metering pump, controlling the flow rate to 0.4 L / min. As the mixture extracts, the diphenylethylene glycosides in the Polygonum multiflorum powder enter the mixture. The extract from the first outlet of the extraction column is temperature-controlled at 30°C via a heat exchanger and enters the second inlet of the adsorption column. The extract from the extraction column is sampled at the sampling port; the diphenylethylene glycoside content should show a near-normal distribution. Continue this extraction and adsorption process until the diphenylethylene glycoside concentration at the adsorption column outlet is below 200 mg / L, indicating extraction is complete.

[0042] Desorption: Prepare a pre-mixed alcohol-water mixture at a ratio of 8:1 ethanol:water and pre-cool it to 15°C. Use a metering pump to deliver this mixture to the second inlet of the adsorption column at a controlled flow rate of 0.5 L / min. When the diphenylethylene glycoside content at the second outlet of the adsorption column exceeds 98.8%, receive the desorbed liquid from the second outlet. Continue desorption until the diphenylethylene glycoside concentration at the second outlet of the adsorption column is below 200 mg / L, indicating completion.

[0043] After desorption, ethanol with a temperature of 60° C. and a content of 95% was introduced into the adsorption column for activation, and the activated resin was reused.

[0044] Concentration: The desorption liquid is passed through a triple-effect parallel-flow evaporator to recover the alcohol-water mixture in the desorption liquid, and the concentrated liquid is evaporated to dryness on a rotary evaporator to obtain a crude product of diphenylethylene glycoside.

[0045] Recrystallization: The crude stilbene glycoside was recrystallized from isopropanol to obtain 0.130 kg of refined stilbene glycoside with a content of 99.21% and a calculated purity of 92.04%. The resulting crystallization mother liquor was combined with the isopropanol and used as the crude stilbene glycoside.

[0046] Example 2

[0047] The preparation process of Example 2 is basically the same as that of Example 1, except that a mixture of ethanol and water with a ratio of 0.1:1 is used for extraction. Finally, 0.126 kg of stilbene glycoside fine product is obtained with a content of 99.66% and a calculated purification rate of 86.61%.

[0048] Example 3

[0049] The preparation process of Example 3 is basically the same as that of Example 1, except that a mixture of ethanol and water with a ratio of 0.3:1 is used for extraction. Finally, 0.133 kg of stilbene glycoside fine product is obtained with a content of 99.02% and a calculated purification rate of 93.99%.

[0050] Example 4

[0051] The preparation process of Example 4 is basically the same as that of Example 1, except that an alcohol-water mixture at 40° C. is used for extraction. Finally, 0.127 kg of stilbene glycoside fine product is obtained, with a content of 99.67% and a calculated purification rate of 90.33%.

[0052] Example 5

[0053] The preparation process of Example 5 is basically the same as that of Example 1, except that an alcohol-water mixture at 60° C. is used for extraction. Finally, 0.134 kg of stilbene glycoside fine product is obtained, with a content of 99.04% and a calculated purification rate of 94.71%.

[0054] Example 6

[0055] The preparation process of Example 6 was essentially the same as that of Example 1, except that cold water at 10°C was continuously passed through the heat exchanger beforehand, and the temperature of the extract was controlled at 20°C for adsorption. The final product obtained was 0.132 kg of fine stilbene glycoside, with a content of 99.17% and a calculated purification rate of 93.42%.

[0056] Example 7

[0057] The preparation process of Example 7 was basically the same as that of Example 1, except that the heat exchange medium inlet flow rate of the heat exchanger was increased to control the temperature of the extract at 40°C for adsorption. Finally, 0.126 kg of fine stilbene glycoside was obtained with a content of 99.19% and a calculated purification rate of 89.19%.

[0058] Example 8

[0059] The preparation process of Example 8 was essentially the same as that of Example 1, except that a mixture of ethanol and water (8:1) was pre-prepared and pre-cooled to 5°C, i.e., the temperature during the desorption process was controlled at 5°C. The final product obtained was 0.131 kg of fine stilbene glycoside, with a content of 99.46% and a calculated purification rate of 92.98%.

[0060] Example 9

[0061] The preparation process of Example 9 was essentially the same as that of Example 1, except that a mixture of ethanol and water (8:1) was pre-prepared and preheated to 20°C, i.e., the temperature during the desorption process was controlled at 20°C. The final product obtained was 0.133 kg of fine stilbene glycoside, with a content of 99.03% and a calculated purification rate of 93.99%.

[0062] Example 10

[0063] The preparation process of Example 10 is basically the same as that of Example 1, except that AB-8 resin is used for adsorption separation. Finally, 0.131 kg of stilbene glycoside fine product is obtained with a content of 99.19% and a calculated purification rate of 92.73%.

[0064] Example 11

[0065] The preparation process of Example 11 is basically the same as that of Example 1, except that HPD-450 resin is used for adsorption separation. Finally, 0.132 kg of stilbene glycoside fine product is obtained, with a content of 99.03% and a calculated purification rate of 93.29%.

[0066] Comparative Example 1

[0067] The preparation process of Comparative Example 1 was essentially the same as that of Example 1, except that the extraction column was replaced with a 20 cm diameter, 80 cm length column, and the aspect ratio after loading the fine Polygonum multiflorum powder was approximately 2.4. The final yield was 0.128 kg of fine stilbene glycosides, with a content of 97.28% and a calculated purification rate of 88.86%.

[0068] Comparative Example 2

[0069] The preparation process of Comparative Example 2 was essentially the same as that of Example 1, except that the adsorption column was replaced with a 22 cm diameter, 100 cm length column, and the XAD-7 adsorption resin was loaded to achieve an aspect ratio of approximately 3.1. The final yield was 0.130 kg of fine stilbene glycoside, with a content of 98.27% and a calculated purification rate of 91.17%.

[0070] Comparative Example 3

[0071] The preparation process of Comparative Example 3 was essentially the same as that of Example 1, except that 12.5 kg of fine Polygonum multiflorum powder and 50 kg of a 0.2:1 ethanol-water mixture were added to a 100 L extraction kettle. The kettle was jacketed with hot water, the temperature was raised to 50° C., and stirring was initiated for 1 hour. After extraction, the kettle was filtered while hot. The filter cake was again added to the extraction kettle, and 50 kg of a 0.2:1 ethanol-water mixture was added for extraction. This process was repeated three times. After extraction, the extract was cooled to 30° C.

[0072] The extract is continuously transported into the adsorption column for adsorption and subsequent desorption process.

[0073] Finally, 0.128 kg of diphenylethylene glycoside was obtained, with a content of 97.62% and a calculated purification rate of 89.17%.

Claims

1. A method for extracting stilbene glycosides from Polygonum multiflorum, characterized in that: The extraction method comprises the following steps: (1) Grind and sieve Polygonum multiflorum to form fine powder; (2) placing the fine powder in an extraction column and extracting it with an extractant to form an extract; (3) the extract is subjected to adsorption and desorption in an adsorption column to form a stilbene glycoside desorption solution; (4) the diphenylethylene glycoside desorption solution is concentrated to form a concentrated solution; (5) the concentrated solution is crystallized with isopropyl alcohol to form the fine product of diphenylethylene glycoside; Wherein, the passing rate of the fine powder in step (1) on a 40-mesh sieve is 100%; the retention rate of the fine powder on a 100-mesh sieve is 100%; and the content of the diphenylethylene glycoside fine product in step (5) is ≥99.0%.

2. The method according to claim 1, characterized in that The aspect ratio of the fine powder in the extraction column in step (2) is 4 to 6:1; the temperature of the extraction process in step (2) is controlled to be 40 to 60° C., the extraction agent is an alcohol-water mixture, the mass ratio of alcohol to water in the alcohol-water mixture is 0.1 to 0.3:1, and the alcohol is selected from at least one of methanol and ethanol.

3. The method according to claim 1, characterized in that The adsorbent used in the adsorption process of step (3) is a medium-polarity macroporous adsorption resin, and the mass ratio of the medium-polarity macroporous adsorption resin to the fine powder of step (2) is 1 to 5:1; the aspect ratio of the medium-polarity macroporous adsorption resin in the adsorption column is 4 to 6:1; and the temperature of the adsorption process of step (3) is controlled to be 20 to 40°C.

4. The method according to claim 3, characterized in that The model of the medium-polarity macroporous adsorption resin is one of AB-8, HPD-450, XAD-7 and XAD-8.

5. The method according to claim 1, wherein The desorbent used in the desorption process of step (3) is an alcohol-water mixture, the mass ratio of alcohol to water in the alcohol-water mixture is 7 to 9:1, the alcohol is selected from at least one of methanol or ethanol, and the temperature of the desorption process of step (3) is controlled to be 5 to 20°C.

6. A device for extracting stilbene glycosides from Polygonum multiflorum, characterized in that: The device comprises an extraction column, a heat exchanger and an adsorption column which are connected in sequence.

7. The device according to claim 6, characterized in that The extraction column consists of a first cylinder, a first upper head, a first lower head and a first support plate placed at the bottom of the first cylinder; a first feeding port is provided at the top center of the first upper head, and a first discharge port is provided on the bottom side of the first cylinder and located above the first support plate; a first inlet is provided on the upper side of the first cylinder, and the first inlet extends to the center of the first cylinder through a pipeline; a first outlet is provided at the bottom center of the first lower head.

8. The device according to claim 6, characterized in that The adsorption column consists of a second cylinder, a second upper head, a second lower head and a second support plate placed at the bottom of the second cylinder; a second feeding port is provided at the top center of the second upper head, and a second discharge port is provided on the bottom side of the second cylinder and located on the upper part of the second support plate; a second inlet is provided on the upper side of the second cylinder, and the second inlet extends to the center of the second cylinder through a pipe; a second outlet is provided at the bottom center of the second lower head.

9. The device according to claim 6, characterized in that The heat exchanger is provided with an inlet, an outlet, a heat exchange medium inlet and a heat exchange medium outlet.

10. The device according to any one of claims 7 to 9, characterized in that: The inlet of the heat exchanger is connected to the first outlet of the extraction column through a pipeline; the outlet of the heat exchanger is connected to the second inlet of the adsorption column through a pipeline.

Images