CN110305177B

CN110305177B - Preparation method of N-acetylneuraminic acid

Info

Publication number: CN110305177B
Application number: CN201910600093.4A
Authority: CN
Inventors: 李翔宇; 汪志明; 杨刚; 陆姝欢; 马凡提
Original assignee: Wuhan Zhongke Optics Valley Green Biotechnology Co ltd; Cabio Biotech Wuhan Co Ltd
Current assignee: Wuhan Zhongke Optics Valley Green Biotechnology Co ltd; Cabio Biotech Wuhan Co Ltd
Priority date: 2019-07-04
Filing date: 2019-07-04
Publication date: 2021-04-13
Anticipated expiration: 2039-07-04
Also published as: CN110305177A

Abstract

The invention relates to a preparation method of N-acetylneuraminic acid, which is mainly improved in that aqueous solution of polysialic acid is subjected to microwave hydrolysis. Compared with the existing acid hydrolysis method, the method of the invention has the advantages of simple operation, low cost, clean production and no environmental pollution. The microwave hydrolysis rate reaches more than 90 percent, the time period is 10-35min, the cyclic hydrolysis is not needed, the by-product of the sialic acid solution obtained after hydrolysis is low, the subsequent purification treatment is convenient, and the yield and the purity of the prepared final product are high. The method of the invention is easy for large-scale production and has high investment return.

Description

Preparation method of N-acetylneuraminic acid

Technical Field

The invention belongs to the field of preparation of compounds, and particularly relates to a preparation method of N-acetylneuraminic acid.

Background

N-acetylneuraminic acid is commonly called sialic acid, and the preparation method mainly comprises a chemical synthesis method, an enzymatic synthesis method, a natural product extraction method, a microbial fermentation method and the like. Wherein the microbial method obtains polysialic acid by fermentation, and then hydrolyzes the polysialic acid to obtain sialic acid monomer. Polysialic acid is a linear homopolymer of sialic acid monomers linked by alpha-2, 8 and/or alpha-2, 9 linkages.

In the prior art, saliva liquid is generally prepared by means of acid hydrolysis, for example, chinese patent CN 104046671 a discloses a method for producing sialic acid by fermentation, wherein the hydrolysis conditions are as follows: 2% of polysialic acid was hydrolyzed with 0.1M hydrochloric acid at 85 ℃ for 2 hours. Chinese patent CN 109336855A also discloses a method for acidolysis of polysialic acid, which comprises adjusting pH to 0.01-4 with strong acid and medium strong acid, and performing cyclic hydrolysis at 40-60 deg.C for 10-120 min.

However, in the acid hydrolysis process, the hydrolysis time is not enough, which easily results in incomplete primary hydrolysis, the yield of the extracted sialic acid monomer is low, or the unhydrolyzed product is filtered out for repeated cyclic hydrolysis, or the hydrolysis time is prolonged, sialic acid hydrolyzed under the condition of long-time high-temperature strong acid is easily degraded to generate byproducts, most of the generated byproducts are isomers, which are extremely difficult to remove in the subsequent purification process, so that a large burden is brought to the subsequent treatment, the hydrolysis condition of the strong acid is serious in corrosion to equipment, the environmental pollution is large, the subsequent neutralization reaction treatment is needed, the treatment cost is high, and the process is relatively complex. And the usual hydrolysis processes in the prior art implicitly teach that the alpha-2, 8 and/or alpha-2, 9 linkages of polysialic acid are more difficult to break completely to obtain sialic acid monomers.

Disclosure of Invention

The invention provides a method for preparing N-acetylneuraminic acid by hydrolyzing polysialic acid by microwaves, and particularly relates to microwave treatment of an aqueous solution of polysialic acid.

Preferably, the microwave hydrolysis conditions are that the hydrolysis temperature is 40-80 ℃ and the pressure is 0.1-0.2 Mpa.

Further preferably, the microwave hydrolysis temperature is 60-70 ℃ and the pressure is 0.1-0.2 Mpa.

Preferably, the hydrolysis time is 10-35 min.

Further preferably, the hydrolysis time is 15-20 min.

The hydrolysis rate of sialic acid has a strong relationship with the time and temperature of hydrolysis, and when the hydrolysis energy is low, the hydrolysis rate is affected, and although many impurities which are difficult to remove are not produced, the final yield is affected. However, rather than hydrolyzing for as long as possible, it is better, or hydrolyzing at as high a temperature as possible, because sialic acid is more likely to change at higher temperatures, which further produces by-products or causes a darker color, which places a greater burden on subsequent processing, and some of which can be removed but most of which are more difficult to remove directly, which directly affects the purity and yield of sialic acid. Therefore, the effect of hydrolysis under the above temperature and time conditions is preferable.

Preferably, the microwave hydrolysis condition is that the microwave power is 300-.

More preferably, the microwave power is 600-800W.

As a preferred scheme of the invention, the conditions of the microwave hydrolysis are that the microwave power is 300-1000W, the pressure is 0.1-0.2Mpa, the hydrolysis temperature is 40-80 ℃, and the hydrolysis time is 10-35 min.

More preferably, the hydrolysis conditions are microwave power of 600-.

Preferably, the mass concentration of the polysialic acid in the aqueous solution of the polysialic acid is controlled to be 20-50 g/L in the hydrolysis process. The hydrolysis rate of polysialic acid is preferably adjusted to the above concentration, and the hydrolysis rate is affected by an excessively high or excessively low concentration. The method for controlling the mass concentration of the polysialic acid comprises concentration or dilution, wherein the concentration can be achieved by adopting a membrane or evaporation concentration and the like.

Preferably, the pH of the sialic acid aqueous solution is adjusted to 4-5. Hydrolysis is performed under weakly acidic conditions, which accelerates the progress of the hydrolysis reaction, and the hydrolyzed sialic acid monomer is less likely to be further degraded than in a strongly acidic environment.

The polysialic acid of the present invention is obtained by fermentation, and the hydrolysis step may be preceded by a step of removing cells by filtration, and preferably, ultrafiltration membrane filtration may be performed so that the solution has an electrical conductivity of less than 2000. mu.S/cm.

The invention also comprises the operation of preparing the N-acetylneuraminic acid crystal from the N-acetylneuraminic acid obtained by hydrolysis, and the specific flow is that the solution after microwave hydrolysis is decolorized and filtered, and then is evaporated, concentrated and crystallized.

Preferably, the decolorization is carried out with activated carbon.

Further preferably, the decoloring temperature is 30-60 ℃, the amount of the activated carbon is 1-4%, and the decoloring time is 20-60 min.

Preferably, the temperature in the evaporation concentration process is 40-60 ℃, the vacuum degree is above-0.09 MPa, and the concentration of the concentrated solution is 300g/L-500 g/L.

Preferably, the crystallization is carried out at a pH of 0.1 to 2.5, a crystallization temperature of 0 to 4 ℃ and a crystallization time of 4 to 16 hours.

Further preferably, the pH of the crystals is 1 to 1.5.

The invention also comprises the operation of further purifying the crystal, comprising the operations of washing, collecting and drying the crystal obtained in the previous step.

Preferably, the crystal is washed by 3-5 times of 95% ethanol during the purification process, the washing time is 1-4 hours, and the temperature is 40-50 ℃.

Preferably, the specific operation of crystal drying is at the temperature of 60-80 ℃, and vacuum drying is carried out for 2-4 hours.

The invention has the following beneficial effects:

1) compared with the existing acid hydrolysis method, the method of the invention has the advantages of simple operation, low cost, clean production and no environmental pollution.

2) The microwave hydrolysis rate reaches more than 90 percent, the time period is 10-35min, the cyclic hydrolysis is not needed, the obtained sialic acid monomer solution contains few derivatives as byproducts, the burden of subsequent purification is reduced, and the yield and the purity of the obtained final product are high.

3) The method of the invention is easy for large-scale production and has high investment return.

Detailed Description

The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

The polysialic acid related in the embodiment is from fermentation liquor obtained after fermentation of escherichia coli, the concentration of the polysialic acid is determined by a resorcinol method in Chinese pharmacopoeia, the purity of the crystal is determined by adopting a high performance liquid phase, and the detection conditions are as follows: shimadzu Lc-15 c; detection Column Bio-Rad AMINEX HPX 87H Organic Analysis Column (300X 7.8 mm); the column temperature is 60 ℃; the mobile phase is 6mmol sulfuric acid, and the flow rate is 0.6 ml/min; the detection wavelength is 210 nm.

Example 1

The embodiment relates to a preparation method of N-acetylneuraminic acid, which comprises the following steps:

1) preparing 10L polysialic acid (PSA) solution with the concentration of 50g/L, placing the solution in a microwave reaction kettle, adjusting the hydrolysis temperature to 70 ℃, the pressure to 0.2Mpa and the microwave power to 800W, performing microwave hydrolysis on the polysialic acid for 15min, sampling and detecting that the PSA concentration of the hydrolyzed solution is 3g/L and the hydrolysis rate is 94%.

2) And (3) decoloring the hydrolysate: cooling to 60 deg.C, decolorizing for 30min with 1% of active carbon, and filtering to obtain clear liquid.

3) Clear liquid concentration: the temperature is 60 deg.C, and the vacuum degree is above-0.09 MPa to obtain 1L concentrate.

4) And (3) crystallization: the pH was 1.5, the crystallization temperature was 4 ℃ and the crystallization time was 16 hours.

5) Collecting the crude crystals: the crude crystals were collected by centrifugation.

6) And (3) crystal washing: washing with 95% ethanol for 4 hours at 40 deg.C with stirring at 200 rpm.

7) And (3) crystal collection: the wet crystals were collected by centrifugation.

8) And (3) drying the crystals: at a temperature of 80 ℃ and a pressure of-0.09 MPa for 2 hours, 400g of dry crystals were obtained.

9) Crystal detection: the SA content is 98.5 percent, and the total yield of the SA is 77.5 percent.

Example 2

1) preparing 20L solution of 30g/L polysialic acid, placing in a microwave reaction kettle, adjusting hydrolysis temperature to 60 deg.C, pressure to 0.1Mpa, microwave power to 600W, and performing microwave hydrolysis on the polysialic acid for 20 min; sampling and detecting that the PSA concentration of the hydrolyzed solution is 2.1g/L and the hydrolysis rate is 93 percent.

2) And (3) decoloring the hydrolysate: cooling to 30 deg.C, decolorizing for 60min with 4% of active carbon, and filtering to obtain clear liquid.

3) Clear liquid concentration: the temperature is 40 ℃, the vacuum degree is more than minus 0.09MPa, and 550mL of concentrated solution is obtained.

4) And (3) crystallization: PH 2, crystallization temperature 0 ℃, crystallization time 12 hours.

5) Collecting the crude crystals: the centrifuge collects the coarse crystals.

6) And (3) crystal washing: washing with 95% ethanol for 2 hours at 50 deg.C with stirring at 200 rpm.

8) And (3) drying the crystals: the temperature was 60 ℃ and-0.09 MPa for 4 hours, to give 150g of dry crystals.

9) Crystal detection: the SA content was 99.2%, and the SA yield was 74.4%.

Example 3

1) preparing 10L polysialic acid solution with the concentration of 50g/L, placing the solution in a microwave reaction kettle, adjusting the pH value of hydrolysis solution to be 4, the hydrolysis temperature to be 60 ℃, the pressure to be 0.1Mpa and the microwave power to be 600W, carrying out microwave hydrolysis on the polysialic acid for 15min, sampling and detecting that the PSA concentration of the hydrolyzed solution is 1g/L and the hydrolysis rate is 98%.

6) And (3) crystal washing: washed with 4L of 95% ethanol for 4 hours at 45 ℃ with stirring at 200 rpm.

8) And (3) drying the crystals: the temperature is 80 ℃ and-0.09 Mpa, and the time is 4 hours, so that dry crystals are obtained.

9) Crystal detection: 0.5 percent of water, 99.2 percent of SA content and 85.3 percent of total SA yield.

Example 4

1) preparing 20L polysialic acid solution with the concentration of 30g/L, placing the solution in a microwave reaction kettle, adjusting the pH value of hydrolysis solution to be 5, the hydrolysis temperature to be 70 ℃, the pressure to be 0.2Mpa and the microwave power to be 800W, carrying out microwave hydrolysis on the polysialic acid for 15min, sampling and detecting that the PSA concentration of the hydrolyzed solution is 0.9g/L and the hydrolysis rate is 97%.

2) And (3) decoloring the hydrolysate: cooling to 50 deg.C, decolorizing for 30min with 1.5% of active carbon, and filtering to obtain clear liquid.

3) Clear liquid concentration: concentrating at 50 deg.C under vacuum degree of-0.09 MPa or more to obtain 1.1L concentrate.

4) And (3) crystallization: the pH was 1.1, the crystallization temperature was 0 ℃ and the crystallization time was 12 hours.

5) Collecting the crude crystals: the centrifuge collects the coarse crystals.

9) Crystal detection: the water content is 0.6 percent, the SA content is 99 percent, and the total SA yield is 82.5 percent.

Example 5

1) preparing 20L polysialic acid solution with the concentration of 30g/L, placing the solution in a microwave reaction kettle, adjusting the pH value of hydrolysate to be 2, the hydrolysis temperature to be 70 ℃, the pressure to be 0.2Mpa and the microwave power to be 800W, carrying out microwave hydrolysis on the polysialic acid for 15min, sampling and detecting that the PSA concentration of the hydrolyzed solution is 0.6g/L and the hydrolysis rate is 98%.

3) Clear liquid concentration: the temperature is 60 ℃, and the vacuum degree is more than-0.09 MPa, so that 1L of concentrated solution is obtained.

8) And (3) drying the crystals: the temperature is 80 ℃ and-0.09 Mpa, and the time is 2 hours, so that dry crystals are obtained.

9) Crystal detection: the SA content is 98.3 percent, and the total yield of SA is 75.7 percent.

Example 6

1) preparing 20L solution of 20g/L polysialic acid, placing in a microwave reaction kettle, adjusting hydrolysis temperature to 40 deg.C, pressure to 0.1Mpa, microwave power to 300W, and performing microwave hydrolysis on the polysialic acid for 35 min; sampling and detecting that the PSA concentration of the hydrolyzed solution is 2g/L and the hydrolysis rate is 90 percent.

2) And (3) hydrolysis and decoloration: cooling to 30 deg.C, decolorizing for 60min with 4% of active carbon, and filtering to obtain clear liquid.

5) Collecting the crude crystals: the centrifuge collects the coarse crystals.

8) And (3) drying the crystals: the temperature was 80 ℃ and-0.09 MPa for 2 hours, yielding 150g of dry crystals.

9) Crystal detection: the SA content was 98.4%, and the SA yield was 72.5%.

Example 7

1) preparing 20L solution of 20g/L polysialic acid, placing in a microwave reaction kettle, adjusting hydrolysis temperature to 80 deg.C, pressure to 0.1Mpa, microwave power to 800W, and performing microwave hydrolysis on the polysialic acid for 10 min; sampling and detecting that the PSA concentration of the hydrolyzed solution is 1.2g/L and the hydrolysis rate is 94 percent.

5) Collecting the crude crystals: the centrifuge collects the coarse crystals.

8) And (3) drying the crystals: at 80 ℃ and-0.09 MPa for 2 hours, 150g of dry crystals are obtained

9) Crystal detection: the SA content was 98.0% and the SA yield was 73.5%.

Comparative example 1

This example is compared with example 1, except that the hydrolysis reaction of polysialic acid is carried out by adding hydrochloric acid to a polysialic acid solution to a solution pH of 1 and reacting at a temperature of 85 ℃ for 2 hours to obtain a sialic acid solution. The hydrolysis rate was 90%, and the subsequent treatment was not changed, whereby the content of sialic acid crystals was 97.8%, and the yield was 64.4%.

Comparative example 2

Compared with the embodiment 1, the difference of the embodiment is mainly that the step 1) is specifically as follows:

preparing 10L solution of 10g/L polysialic acid, placing in a microwave reaction kettle, adjusting hydrolysis temperature to 70 ℃, pressure to 0.2Mpa and microwave power to 800W, and performing microwave hydrolysis on the polysialic acid for 10 min; the hydrolysis rate was 85%, and the subsequent treatment was not changed, whereby the sialic acid content was 90.2%, and the yield was 67.7%.

Comparative example 3

preparing 10L solution of 60g/L polysialic acid, placing in a microwave reaction kettle, adjusting hydrolysis temperature to 70 ℃, pressure to 0.2Mpa and microwave power to 800W, and performing microwave hydrolysis on the polysialic acid for 20 min; the hydrolysis rate was 88%, and the subsequent treatment was not changed, whereby the sialic acid content was 97.2%, and the yield was 65.7%.

Comparative example 4

preparing 10L solution of 50g/L polysialic acid, placing in a microwave reaction kettle, adjusting hydrolysis temperature to 90 deg.C, pressure to 0.2Mpa, microwave power to 1200W, and performing microwave hydrolysis on the polysialic acid for 5 min; the hydrolysis rate was 90%, and the subsequent treatment was unchanged, so that the obtained sialic acid was yellowish in color, with a content of 96.1% and a yield of 65%.

Comparative example 5

preparing 10L solution of polysialic acid with concentration of 50g/L, placing in a microwave reaction kettle, adjusting hydrolysis temperature to 35 deg.C, pressure to 0.2Mpa, microwave power to 200W, and performing microwave hydrolysis on the polysialic acid for 50 min; the hydrolysis rate was 83%, and the sialic acid thus obtained, content was 97.7% without any change in the subsequent treatment, and the yield was 59.0%.

Although the invention has been described in detail hereinabove by way of general description, specific embodiments and experiments, it will be apparent to those skilled in the art that many modifications and improvements can be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.

Claims

1. A preparation method of N-acetylneuraminic acid is characterized by comprising the following steps:

1) preparing 10L of solution with the concentration of 50g/L from polysialic acid, placing the solution in a microwave reaction kettle, adjusting the pH value of hydrolysis solution to be 4, the hydrolysis temperature to be 60 ℃, the pressure to be 0.1Mpa and the microwave power to be 600W, carrying out microwave hydrolysis on the polysialic acid for 15min, sampling and detecting that the PSA concentration of the hydrolyzed solution is 1g/L, and the hydrolysis rate is 98%;

2) and (3) decoloring the hydrolysate: cooling to 60 deg.C, decolorizing for 30min with 1% of active carbon, and filtering to obtain clear solution;

3) clear liquid concentration: the temperature is 60 ℃, and the vacuum degree is more than-0.09 MPa, so that 1L of concentrated solution is obtained;

4) and (3) crystallization: the PH value is 1.5, the crystallization temperature is 4 ℃, and the crystallization time is 16 hours;

5) collecting the crude crystals: centrifuging and collecting coarse crystals;

6) and (3) crystal washing: washing with 4L of 95% ethanol at 45 deg.C for 4 hr, and stirring at 200 rpm;

7) and (3) crystal collection: centrifugally collecting and washing the wet crystals;