Production process of high-stability gastrodin

Abstract

The application provides a high-stability gastrodin production process, which takes gastrodin tetraacetate as a starting material, and sequentially undergoes pentaacetylation reaction, centrifugation and drying to obtain a gastrodin pentaacetate intermediate; then gradient saponification refining is adopted, that is, preliminary hydrolysis is first carried out by using a low-concentration lye, and then deep saponification is carried out by using a high-concentration lye; after saponification, the product is subjected to centrifugation, drying and crushing to obtain a finished product; an ultrasonic-assisted crystallization step is added after saponification, and an inert gas atmosphere coating is carried out after crushing. The glycosidic bond breakage caused by strong alkali is effectively avoided through gradient saponification, and the key problems of low product purity and poor stability in the existing process are solved in combination with ultrasonic crystallization and inert gas protection. The obtained gastrodin product has the remarkable characteristics of high purity, few impurities and excellent stability, and has the following indexes: purity ≥ 99.1%, related substances ≤ 0.45%, and content decrease rate ≤ 0.8% after 18 months of accelerated test.

Description

Technical Field

[0001] This invention relates to the field of pharmaceutical chemical synthesis technology, and in particular to a highly stable gastrodin production process. Background Technology

[0002] Gastrodin, chemically known as 4-hydroxybenzaldehyde-β-D-glucopyranoside, is the main active ingredient of the traditional Chinese medicine Gastrodia elata Bl. It possesses various pharmacological activities, including sedation, hypnosis, analgesia, and neuroprotection, and is widely used in clinical practice. Currently, the industrial production of gastrodin mainly falls into two categories: plant extraction and chemical synthesis. Plant extraction is affected by factors such as the origin of the raw material, harvesting season, and storage conditions, resulting in problems such as large fluctuations in product purity, low extraction rates, high production costs, and strong resource dependence, making it difficult to meet the needs of large-scale, standardized production of pharmaceutical-grade products. Chemical synthesis, due to its strong process controllability and stable yield, has become the mainstream preparation method. This method typically uses gastrodin tetraacetyl or gastrodin pentaacetyl as key intermediates, removing the acetyl group through saponification and purification to obtain the finished gastrodin product.

[0003] However, existing chemical synthesis processes, especially in the key refining steps of preparing gastrodin from acetylated intermediates via saponification, still face several technical bottlenecks that directly affect the quality and stability of the final product. Existing processes often employ a single, high-concentration strong alkali for one-step saponification and hydrolysis. These harsh reaction conditions easily trigger side reactions, leading to the breakage of key glycosidic bonds in the gastrodin molecule, or degradation such as oxidation and isomerization. This results in increased content of related substances, making it difficult to consistently achieve the purity required for high-end pharmaceutical raw materials, and the product is prone to yellowing. Conventional crystallization processes lack directional control, leading to irregular crystal morphology, uneven particle size distribution, and a tendency for particle aggregation. This not only reduces the product's flowability and uniformity but also further affects purity and storage stability due to impurities adsorbed on the crystal surface. Furthermore, the gastrodin molecule contains multiple hydroxyl groups, making it hygroscopic and sensitive to light, heat, and oxygen. The existing production process lacks effective post-processing methods for stability, which makes the raw materials susceptible to hydrolysis and oxidation during storage, especially in high temperature and high humidity environments. This results in a decrease in the content of the main components and a significant increase in related substances, thereby shortening the effective shelf life of the product and increasing quality risks.

[0004] Therefore, there is an urgent need to develop a production process that can improve the purity of gastrodin and enhance product stability. Summary of the Invention

[0005] In view of this, the present invention proposes a highly stable gastrodin production process to solve the above problems.

[0006] The technical solution of this invention is achieved as follows: a highly stable gastrodin production process, comprising the following steps: S1. Pentaacetylation reaction: Gastrodin tetraacetyl is added to the reaction system, and the reaction temperature, time and pH are controlled to carry out the pentaacetylation reaction; S2, First centrifugation: Centrifuge the pentaacetylation reaction product and collect the solid phase; S3. First drying: The solid phase is dried to obtain gastrodin pentaacetyl intermediate; S4. Saponification and refining: The gastrodin pentaacetyl intermediate is saponified and refined in a gradient manner, with the reaction temperature and time controlled. S5. Secondary centrifugation: Centrifuge the saponified and refined products to collect the solid phase. S6. Secondary drying: Drying the solid phase from the secondary centrifugation; S7. Crushing: Crushing the dried product and controlling the particle size; S8. Packaging and warehousing.

[0007] Preferably, the conditions for the pentaacetylation reaction in step S1 are: reaction temperature 35-45℃, reaction time 2-3h, and pH value of the reaction system controlled at 6.5-7.5. In order to promote a mild and efficient reaction, 0.2-0.5% of p-toluenesulfonic acid by mass of gastrodin tetraacetyl is added to the reaction system as a catalyst.

[0008] Preferably, the conditions for the centrifugation in step S2 are: centrifugation speed of 8000-10000 r / min, centrifugation time of 15-20 min, and centrifugation temperature controlled at 20-25℃. These conditions facilitate efficient and low-temperature separation of the intermediate solid phase and the reaction mother liquor, reducing product residue and degradation in the mother liquor.

[0009] Preferably, the primary drying in step S3 is vacuum drying, with a drying temperature of 40-50℃, a vacuum degree of -0.08~-0.09MPa, and a drying time of 1.5-2h. After drying, the moisture content of the gastrodin pentaacetyl intermediate is ≤5%. These conditions can quickly remove moisture at a relatively low temperature, and the moisture content of the gastrodin pentaacetyl intermediate after drying should be controlled to ≤5%, providing a stable raw material for the next saponification reaction.

[0010] Preferably, the gradient saponification refining in step S4 includes: first, adding the intermediate to a 5-8% (w / w) sodium hydroxide aqueous solution for preliminary hydrolysis at 55-65°C for 0.8-1.5 h, and then performing deep saponification in a 25-30% (w / w) sodium hydroxide aqueous solution at 75-85°C for 1.5-2.5 h. The mass-to-volume ratio (g / mL) of the intermediate to the aqueous solution is 1:8-1:12. Gradient saponification can effectively avoid the breakage caused by the instantaneous and violent hydrolysis of glycosidic bonds under strong alkali and high temperature, thereby improving the selectivity of the reaction and the product yield.

[0011] Preferably, the conditions for the second centrifugation in step S5 are: centrifugation speed 6000-8000 r / min, centrifugation time 10-15 min, centrifugation temperature 25-30℃, and the solid phase after centrifugation is washed with deionized water 2-3 times to thoroughly remove residual alkali and salt.

[0012] Preferably, the particle size of the pulverized material in step S7 is controlled to be 120-150 mesh, and the proportion of residue on the sieve after pulverization is ≤3%. This ensures that the product has a uniform particle size distribution and good flowability.

[0013] Preferably, after the saponification and refining in step S4, ultrasonic-assisted crystallization is added. An ethanol aqueous solution with a volume fraction of 10-15% is added to the saponification and refining product, and the product is subjected to ultrasonic treatment and then allowed to stand for crystallization.

[0014] More preferably, the parameters for the ultrasonic-assisted crystallization are: power 150-200W, temperature 25-30℃, ultrasonic treatment for 10-15 minutes, static crystallization temperature 4-8℃, and time 8-12 hours. After crystallization, the crystals are filtered through a 0.22μm microporous membrane. Utilizing the ultrasonic cavitation effect promotes crystal nucleus generation and uniform distribution, which helps to form crystals with uniform particle size and higher purity. Filtration with a 0.22μm microporous membrane after crystallization further ensures the cleanliness of the product.

[0015] Preferably, after pulverization in step S7, the gas is coated with an inert gas atmosphere, wherein the inert gas is argon, the oxygen content of the atmosphere is ≤0.5%, the pressure is 0.12-0.15 MPa, and the process involves circulating purging for 5-10 minutes at a flow rate of 5-8 L / min. This treatment forms an inert gas protective layer on the surface of the gastrodin particles, isolating them from oxygen and moisture, and significantly improving the storage stability of the final product.

[0016] Compared with the prior art, the beneficial effects of the present invention are: This invention employs a gradient process of low-concentration preliminary hydrolysis and high-concentration deep saponification to avoid side reactions such as glycosidic bond breakage caused by a single strong alkaline environment, achieving complete hydrolysis of the gastrodin pentaacetyl intermediate. Combined with a p-toluenesulfonic acid catalyst, the integrity of the gastrodin molecular structure is gently protected, resulting in a product purity ≥99.1% and related substances content ≤0.45%. Ultrasonic-assisted crystallization utilizes cavitation to promote uniform crystal nucleus formation, resulting in a regular, glossy crystal morphology with a particle size D50 as low as 38.7 μm, exhibiting no significant agglomeration and significantly improved flowability and dispersibility. An additional argon atmosphere coating step, through inert gas circulation purging and replacing air between particles, forms a dense protective layer on the product surface, isolating oxygen and moisture and inhibiting oxidative hydrolysis degradation at its source. After storage at 40℃ and 75% relative humidity for 18 months, the product's content decreased by only 0.8%.

[0017] This invention precisely optimizes and limits the key parameters of each production step, forming a stable and repeatable standardized operating procedure. The steps are seamlessly connected, the overall process has high repeatability, and energy consumption and costs are controllable, making it highly suitable for the large-scale, high-quality production of gastrodin raw materials. Detailed Implementation

[0018] To better understand the technical content of this invention, specific embodiments are provided below to further illustrate the invention.

[0019] Unless otherwise specified, the experimental methods used in the embodiments of this invention are all conventional methods.

[0020] Unless otherwise specified, all materials and reagents used in the embodiments of this invention are commercially available.

[0021] Example 1 A highly stable gastrodin production process is carried out according to the following steps: S1. Pentaacetylation reaction: In the reaction vessel, add 100g of gastrodin tetraacetyl, adjust the pH of the system to stabilize at 7.0, start stirring and heat to 40℃, add 0.3g of p-toluenesulfonic acid, control the pH of the reaction system to 7.0, and react for 2.5 hours.

[0022] S2. First centrifugation: After the reaction is complete, transfer the material to a centrifuge and centrifuge at 9000 r / min and 22℃ for 18 minutes to collect the solid phase.

[0023] S3. First drying: The solid phase was placed in a vacuum drying oven and dried at 45℃ and -0.085MPa for 1.8 hours to obtain a gastrodin pentaacetyl intermediate with a moisture content of 4.2%.

[0024] S4, Saponification and Refining: Preliminary hydrolysis: Add the intermediate to 1000 mL of 6% sodium hydroxide aqueous solution and hydrolyze for 1 h; Deep saponification: Add a 28% sodium hydroxide aqueous solution to the system to make the alkali concentration of the system reach about 25%, raise the temperature to 80°C, and continue stirring for 2 hours to carry out deep saponification.

[0025] S5. Second centrifugation: Cool the saponification solution to 28°C, centrifuge at 7000 r / min for 12 minutes, collect the solid phase, and wash the solid phase 3 times with deionized water.

[0026] S6. Secondary drying: The washed wet product is vacuum dried at 50°C to constant weight.

[0027] S7. Grinding: Grind the dried crude gastrodin product using a grinder, pass it through a 140-mesh sieve, and control the residue on the sieve to be ≤2.5%.

[0028] S8. Packaging and Warehousing: Weigh the pulverized product, package it inner and outer, and print batch numbers and affix labels. After passing quality inspection (content, related substances, moisture, particle size, etc.) and quality audit, it is stored in the warehouse.

[0029] Example 2 Based on Example 1, to further improve product purity and crystal morphology, an ultrasonic-assisted crystallization step is added after step S4 (saponification refining): Add two volumes of 12% (v / v) ethanol aqueous solution to the saponification product, set the ultrasonic power to 180W and the temperature to 28℃, and sonicate for 12 min; then transfer to a low temperature chamber, set the temperature to 6℃, and let it stand for crystallization for 10 h; after crystallization, filter through a 0.22μm microporous membrane and collect the crystals.

[0030] Example 3 Based on Example 1, to further improve the storage stability of the final product, an inert gas atmosphere coating step is added after pulverization in step S7: The pulverized gastrodin powder was placed in a sealable coating device, evacuated, and then filled with high-purity argon gas, controlling the oxygen content inside the device to ≤0.3% and maintaining the pressure at 0.13 MPa. Argon gas was purged at a flow rate of 6 L / min for 8 minutes to ensure that the argon gas fully replaces the air between the particles and adsorbs onto the particle surface. After processing, under a slightly positive pressure argon atmosphere, the S8 packaging operation was quickly performed.

[0031] Example 4 Based on Example 2, to further improve the storage stability of the final product, an inert gas atmosphere coating step is added after pulverization in step S7: The pulverized gastrodin powder was placed in a sealable coating device, evacuated, and then filled with high-purity argon gas, controlling the oxygen content inside the device to ≤0.3% and maintaining the pressure at 0.13 MPa. Argon gas was purged at a flow rate of 6 L / min for 8 minutes to ensure that the argon gas fully replaces the air between the particles and adsorbs onto the particle surface. After processing, under a slightly positive pressure argon atmosphere, the S8 packaging operation was quickly performed.

[0032] Comparative Example 1 This comparative example uses the conventional saponification method: Saponification and refining: The intermediate was directly added to 1000 mL of 25% sodium hydroxide aqueous solution, heated to 80°C, and stirred for 3 hours; the remaining steps were the same as in Example 1.

[0033] Comparative Example 2 This comparative example uses a conventional crystallization method: Low-temperature crystallization: Add 2 times the volume of 12% v / v ethanol aqueous solution to the saponification product, transfer directly to a low-temperature chamber at 6°C for crystallization for 10 hours, and then filter through a 0.22μm microporous membrane; the remaining steps are the same as in Example 2.

[0034] Comparative Example 3 In this comparative example, the catalyst p-toluenesulfonic acid in step S1 was replaced with an equal amount of the conventional catalyst concentrated sulfuric acid, while the remaining reaction conditions (temperature, pH, time) remained unchanged. All subsequent steps S2-S8 were the same as in Example 4.

[0035] Performance testing 1. Testing standards: Based on the 2025 edition of the Pharmacopoeia of the People's Republic of China, Part I, and ICH Q1A (Guideline for Stability Testing). 2. Detection method: 2.1 Gastrodin purity / related substances: High performance liquid chromatography (HPLC), detection wavelength 220 nm, chromatographic column C18 (4.6 mm × 250 mm, 5 μm); 2.2 Crystal morphology / particle size: Scanning electron microscope (SEM) + laser particle size analyzer; 2.3 Storage stability: Accelerated test at 40℃ and 75% relative humidity, content changes were detected after 6 months, 12 months, and 18 months; 2.4 Moisture content: Karl Fischer titration; 2.5 Particle size distribution: sieving method + laser particle size analyzer (D50 is the cumulative 90% particle size).

[0036] 3. Test Results Table 1: Test Results of Core Quality Indicators of Gastrodin Products

[0037] Table 2: Results of D50 Detection of Crystal Morphology and Particle Size of Gastrodin Products

[0038] Table 3: Results of the test on the storage stability and content decline rate of gastrodin products

[0039] Note: "-" indicates that no stability test was conducted for 18 months. Conclusion: The purity of gastrodin in Examples 1-4 was ≥99.1%, and the content of related substances was ≤0.45%, with Example 4 having a purity as high as 99.6% and a related substance content as low as 0.25%. In contrast, Comparative Example 1 had a purity of only 98.2% and a related substance content of 1.20%, while Comparative Example 3 had a related substance content of 0.90%. This indicates that the gradient process of low-concentration preliminary hydrolysis and high-concentration deep saponification used in this invention can avoid side reactions caused by local over-alkaliness, achieve complete hydrolysis of the gastrodin pentaacetyl intermediate, and effectively protect the integrity of the gastrodin molecular structure by using p-toluenesulfonic acid as a catalyst, significantly reducing the generation of impurities.

[0040] Compared with the conventional crystallization methods of Example 1 and Comparative Example 2, after introducing ultrasound-assisted crystallization in Examples 2 and 4, the product purity was further improved to over 99.5%, the related substances were reduced to below 0.28%, and the crystal morphology was regular with good luster. The particle size D50 was as low as 38.7 μm and 39.1 μm, respectively, with no agglomeration. This indicates that ultrasound-assisted crystallization promotes directional crystal growth by breaking the local concentration unevenness of the supersaturated solution. It not only optimizes the regularity of the crystal morphology but also reduces the risk of particle agglomeration, laying a structural foundation for improving subsequent storage stability.

[0041] In Examples 1 and Comparative Examples 1-3, which did not have an additional inert gas coating, the content reduction rate after 12 months was ≥2.0%, with Comparative Example 1 reaching 4.5%. Because the stability did not meet the requirements for long-term storage, an 18-month test was not conducted. Examples 3 and 4, which added inert gas coating, showed a content reduction rate of only 1.5% and 0.8% respectively after 18 months. In particular, the optimized process of Example 4 showed a content reduction rate of less than 1% after 18 months, which was far better than the 2.1% of Example 2. This indicates that the step can effectively isolate oxygen and moisture, and fundamentally inhibit the oxidation and hydrolytic degradation of gastrodin during storage.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A highly stable gastrodin production process, characterized in that, Includes the following steps: S1. Pentaacetylation reaction: Gastrodin tetraacetyl is added to the reaction system, and the reaction temperature, time and pH are controlled to carry out the pentaacetylation reaction; S2, First centrifugation: Centrifuge the pentaacetylation reaction product and collect the solid phase; S3. First drying: The solid phase is dried to obtain gastrodin pentaacetyl intermediate; S4. Saponification and refining: The gastrodin pentaacetyl intermediate is saponified and refined in a gradient manner, with the reaction temperature and time controlled. S5. Secondary centrifugation: Centrifuge the saponified and refined products to collect the solid phase. S6. Secondary drying: Drying the solid phase from the secondary centrifugation; S7. Grinding: Grind the dried product and control the particle size. S8. Packaging and warehousing.

2. The gastrodin production process as described in claim 1, characterized in that, The conditions for the pentaacetylation reaction in step S1 are: reaction temperature 35-45℃, reaction time 2-3h, pH value of the reaction system controlled at 6.5-7.5, and 0.2-0.5% p-toluenesulfonic acid by mass of gastrodin tetraacetyl as a catalyst added to the reaction system.

3. The gastrodin production process as described in claim 1, characterized in that, The conditions for centrifugation in step S2 are: centrifugation speed 8000-10000 r / min, centrifugation time 15-20 min, and centrifugation temperature controlled at 20-25℃.

4. The gastrodin production process as described in claim 1, characterized in that, In step S3, the first drying is vacuum drying, with a drying temperature of 40-50℃, a vacuum degree of -0.08~-0.09MPa, and a drying time of 1.5-2h. After drying, the moisture content of the gastrodin pentaacetyl intermediate is ≤5%.

5. The gastrodin production process as described in claim 1, characterized in that, The gradient saponification refining in step S4 includes: first, adding the intermediate to a 5-8% sodium hydroxide aqueous solution at 55-65°C for preliminary hydrolysis for 0.8-1.5 hours, and then performing deep saponification in a 25-30% sodium hydroxide aqueous solution at 75-85°C for 1.5-2.5 hours. The mass-to-volume ratio of the intermediate to the aqueous solution is 1:8-1:12 (g / mL).

6. The gastrodin production process as described in claim 1, characterized in that, The conditions for the second centrifugation in step S5 are: centrifugation speed 6000-8000 r / min, centrifugation time 10-15 min, centrifugation temperature 25-30℃, and the solid phase after centrifugation is washed with deionized water 2-3 times.

7. The gastrodin production process as described in claim 1, characterized in that, In step S7, the particle size of the pulverized material is controlled to be 120-150 mesh, and the proportion of the residue after sieving is ≤3%.

8. The gastrodin production process as described in claim 1, characterized in that, After saponification and refining in step S4, ultrasonic-assisted crystallization is added. 1.5-2.5 times the volume of 10-15% (v / v) ethanol aqueous solution is added to the saponified and refined product, and the mixture is subjected to ultrasonic treatment and then allowed to stand for crystallization.

9. The gastrodin production process as described in claim 8, characterized in that, The parameters for ultrasound-assisted crystallization are: power 150-200W, temperature 25-30℃, ultrasound for 10-15min, static crystallization temperature 4-8℃, time 8-12h, and then filtered through a 0.22μm microporous membrane.

10. The gastrodin production process as described in claim 1, characterized in that, After crushing in step S7, the gas is coated with an inert gas atmosphere, wherein the inert gas is argon, the oxygen content of the atmosphere is ≤0.5%, the pressure is 0.12-0.15MPa, and the gas is purged by circulation for 5-10 minutes at a flow rate of 5-8L / min.

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