A polysulfide and a method for producing and using the same

Abstract

The application belongs to the technical field of compound synthesis, and discloses a polysulfide as well as a preparation method and application thereof. The preparation method comprises the following steps: adding a sulfide salt into an oxidant solution to perform an oxidation reaction; then, heating, and adding elemental sulfur under the condition of stirring to perform a polymerization reaction; and after the reaction is completed, crystallization is performed to obtain the polysulfide. The polysulfide is prepared by using an oxidation method, the reaction condition is mild, the requirement for a reaction device is low, and the operation is simple and safe, so that the polysulfide is not only suitable for laboratory preparation, but also is beneficial to large-scale production. The polysulfide prepared by using the application can significantly improve the yield of ergothioneine when the polysulfide is used for preparing ergothioneine, and when the polysulfide is a polymer with a single molecular weight, the yield of ergothioneine is about 1.9 times of that of commercially available polysulfide.

Description

Technical Field

[0001] This invention belongs to the field of compound synthesis technology, specifically relating to a polysulfide, its preparation method, and its application. Background Technology

[0002] Ergothioneine (EGT) is a special amino acid of thiohistidine betaine with unique redox properties and unique physiological effects on plants and animals. It is a natural antioxidant and a potential nutritional food with great application prospects in the food, cosmetics and pharmaceutical industries.

[0003] Numerous studies have been conducted on ergothioneine synthesis methods. One synthetic pathway involves the direct conversion of CH4 to CS4 using polysulfides (such as potassium polysulfide and sodium polysulfide) as a sulfur source, under the action of sulfide-transferases (St enzymes), thus converting histidine betaine into ergothioneine. Currently, most polysulfides used are provided by Sigma-Aldrich, and no literature has publicly disclosed or described any methods for their preparation. Furthermore, the yield of ergothioneine prepared from polysulfides needs further improvement. Therefore, research on polysulfide preparation methods is of great significance, and there is an urgent need to develop polysulfides that can improve the yield of ergothioneine. Summary of the Invention

[0004] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a polysulfide, its preparation method, and its application. The polysulfide prepared by this invention can improve the yield of ergothioneine.

[0005] This invention provides a method for preparing polysulfides.

[0006] Specifically, a method for preparing a polysulfide includes the following steps:

[0007] An oxidation reaction is carried out by adding a sulfide salt to an oxidant solution; then the temperature is raised and elemental sulfur is added while stirring to carry out a polymerization reaction; after the reaction is completed, crystallization is performed to obtain a polysulfide.

[0008] Preferably, the oxidant solution includes one of hydrogen peroxide solution, hypochlorous acid solution, and hypochlorite solution; more preferably, the oxidant solution is hydrogen peroxide solution.

[0009] Preferably, the hydrogen peroxide solution has a mass percentage of 0.2%-2%; more preferably, the hydrogen peroxide solution has a mass percentage of 0.3%-1%; and even more preferably, the hydrogen peroxide solution has a mass percentage of 0.3%-0.8%.

[0010] Preferably, the hypochlorite solution is a sodium hypochlorite solution.

[0011] Preferably, the sodium hypochlorite solution has a mass percentage of 5%-20%; more preferably, the sodium hypochlorite solution has a mass percentage of 8%-15%.

[0012] Preferably, the sulfide salt is potassium sulfide or / and sodium polysulfide.

[0013] Preferably, during the addition of sulfide salts, the feeding rate needs to be controlled so that the temperature of the oxidation reaction does not exceed 35°C; more preferably, during the addition of sulfide salts, the feeding rate needs to be controlled so that the temperature of the oxidation reaction does not exceed 30°C.

[0014] Preferably, the final temperature of the heating is 50-80°C; more preferably, the final temperature of the heating is 55-70°C.

[0015] Preferably, the mass ratio of elemental sulfur to the sulfide salt is (2-15):40; more preferably, the mass ratio of elemental sulfur to the sulfide salt is (4-9):40; even more preferably, the mass ratio of elemental sulfur to the sulfide salt is (5-7):40.

[0016] Preferably, the elemental sulfur is sublimed sulfur powder.

[0017] Preferably, the polymerization reaction temperature is 50-80℃ and the polymerization reaction time is 1-5h; more preferably, the polymerization reaction temperature is 55-70℃ and the polymerization reaction time is 1.5-3h.

[0018] Preferably, when the oxidant solution is a hydrogen peroxide solution, the crystallization process is as follows: the reaction solution is filtered and then evaporated using a rotary evaporator.

[0019] Preferably, when the oxidant solution is a hypochlorite solution, the crystallization process is as follows: using a rotary evaporator to evaporate sodium chloride and sodium sulfate in sequence, when a large amount of sodium sulfate and sodium chloride crystals are produced in the bottle, the solution in the bottle is filtered while hot, and the filtrate is transferred to the rotary evaporator bottle for further concentration. This process is repeated 3-6 times until the solution is concentrated to a solid, thus obtaining the polysulfide.

[0020] The reaction mechanism in the above-mentioned method for preparing polysulfides is as follows. Taking sodium sulfide as an example, the following reaction occurs under the action of an oxidizing agent solution:

[0021] Na2S→S+Na2SO4+Na2SO3;

[0022] Na2S + nS → Na2S2;

[0023] Na₂S₂ + nS → Nan S n+1 .

[0024] The present invention also provides a polysulfide.

[0025] Specifically, a polysulfide is prepared by the above-described method, wherein the polysulfide is a polymer with a single molecular weight or a mixture of two molecular weights.

[0026] Preferably, when the polysulfide is sodium polysulfide and is a polymer with a single molecular weight, the weight-average molecular weight of the sodium polysulfide is approximately 12597, and the mass ratio of S to Na is 1.5:1.

[0027] This invention also provides an application of polysulfides.

[0028] Specifically, the application of the above-mentioned polysulfides in the preparation of ergothioneine.

[0029] The specific application process is as follows: using TMH (histidine betaine) as a substrate, under the catalysis of St enzyme (whose amino acid sequence is shown in SEQ ID NO: 1), it reacts with the polysulfide prepared in this invention to obtain ergothioneine.

[0030] SEQ ID NO: 1: MKSISTDELLENLHRYKVIDIRSVDAYNGWKENGENRGGHIRSAKSLPYKWVNYIDWIEIVRSKDILPQDKLVIYGYDSEKAEEVARMFEKAGYTDLNIYPSFFE WVERNLPMDRLERYRHLVSPDWLNQLITTDNAPEYDNDKYVICHCHYRNPVDYEKGHIPGSIPLDTNSLESEDTWNRRSPEELKDALENAGISSETTVIVYGRFSYPKND DPFPGSSAGHLGAMRCAFIMLYAGVKDVRILNGGLQSWLDAGYNVTTEPAKISKVSFGANIPLNPKIAVDLEEAKEILSDPGKKLVSVRSWREYIGEVSGYNYIEKKGRI PGSVFGDCGTDAYHMENYRNLDHTMREYHEIEDKWKELGITPEKRNAFYCGTGWRGSEAFLNAWLMGWDNAAVFDGGWFEWSNNDLPFETGVPEK(Source Methanosalsum zhilinae).

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] (1) In the preparation method provided by this invention, some sulfide salts are rapidly oxidized upon contact with the oxidizing agent solution to form micro-sulfur elemental. The micro-sulfur elemental is characterized by extremely fine particles. The elemental sulfur added in conjunction with the micro-sulfur elemental can combine with the remaining sodium sulfide in the solution to produce polysulfides. This invention prepares polysulfides by oxidation, which has mild reaction conditions, low requirements for reaction equipment, and is simple and safe to operate. It is not only suitable for laboratory preparation but also beneficial for large-scale production.

[0033] (2) By selecting different oxidant solutions, this invention can prepare polymers with a single molecular weight or mixtures of two molecular weights. Whether it is a polymer with a single molecular weight or a mixture of two molecular weights, the yield of ergothioneine can be significantly improved during the preparation of ergothioneine. When it is a polymer with a single molecular weight, the yield of ergothioneine is about 1.9 times that of commercially available polysulfides. Attached Figure Description

[0034] Figure 1 The molecular weight distribution diagram of the polysulfide prepared in Example 1;

[0035] Figure 2 The molecular weight distribution diagram of the polysulfide prepared in Example 2;

[0036] Figure 3 The graph shows the effect of polysulfides synthesized in different embodiments and commercially available polysulfides on EGT yield. Detailed Implementation

[0037] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0038] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0039] Example 1

[0040] A method for preparing sodium polysulfide includes the following steps:

[0041] (1) Oxidation: Take a 1000mL beaker and add 600mL of 0.5% hydrogen peroxide solution. Then, start stirring and slowly add 40g of sodium sulfide crystals. Monitor the reaction temperature and control the feeding rate during the addition process to ensure that the reaction temperature does not exceed 30℃. After the addition is complete, the reaction system will be golden yellow. Keep stirring for 1 hour to ensure that the system reacts completely.

[0042] (2) Polymerization: After the oxidation reaction is complete, the temperature is raised to 60°C, and then 2.5, 5.5 and 11 g of sublimed sulfur are slowly added under vigorous stirring. Stirring is continued until most of the sublimed sulfur dissolves and the reaction continues for 3 hours.

[0043] (3) Crystallization: The solution after the reaction is filtered, and then the crystals are obtained by rotary evaporation to obtain a reddish-brown solid with a special odor, which is sodium polysulfide.

[0044] The sodium polysulfide prepared in this embodiment was sent to Science Compass Testing Company for molecular weight determination by dextran gel chromatography (GPC) and the Na and S content in sodium polysulfide was determined by ICP-OES / MS.

[0045] 1. GPC dextran gel chromatography was performed using an Agilent 1260 Infinity II chromatograph, with water as the mobile phase. The properties of sodium polysulfide were characterized, and the results are shown in Tables 1 and 2. Figure 1 .

[0046] Figure 1 The molecular weight distribution diagram of the polysulfide prepared by adding 5.5g of sublimed sulfur in Example 1 is shown below. Figure 1 As can be seen, GPC gel chromatography shows a single peak, indicating that the sodium polysulfide prepared by hydrogen peroxide has a single molecular weight, with a weight-average molecular weight of approximately 12597 and a peak area of ​​100%. Specific peak results and average weight-average molecular weights are shown in Tables 1 and 2, respectively.

[0047] Table 1 Peak Results

[0048]

[0049] Table 2 Average weight-average molecular weight

[0050]

[0051] GPC dextran gel permeation chromatography revealed that the sodium polysulfide prepared in this embodiment is a polymer with a high degree of polymerization and a single molecular weight.

[0052] 2. ICP-OES / MS determination was performed using a PerkinElmer NexION 2000 (MS) instrument with an nebulizer flow rate of 0.6 ppm, sample absorption delay of 9 seconds, instrument stabilization delay of 7 seconds, copy readout time of 8 seconds, and RF power of 1300 W. The ICP-OES / MS results are shown in Table 3.

[0053] Table 3

[0054]

[0055] As shown in Table 3, the mass ratio of S to Na in sodium polysulfide prepared by hydrogen peroxide oxidation is 1.5:1.

[0056] Example 2

[0057] A method for preparing a polysulfide includes the following steps:

[0058] (1) Oxidative coupling: Take 300 mL and slowly add 40 g of sodium sulfide under rapid stirring, then slowly pour in 320 mL of 10% NaClO solution and stir for 1 h.

[0059] (2) Polymerization: The reaction system after oxidative coupling is heated to 70°C, and 2.5, 5.5 and 11 g of sublimed sulfur powder are added to it respectively, and the reaction is stirred for 120 min.

[0060] (3) Crystallization: After the stirring reaction is complete, turn on the cooling device of the rotary evaporator to about 2°C and simultaneously turn on the vacuum pump. Heat the water bath of the rotary evaporator to 70°C to start crystallization. As the volume of the solution in the sample bottle of the rotary evaporator decreases, sodium chloride and sodium sulfate will precipitate out in sequence. When a large amount of sodium sulfate and sodium chloride crystals are produced in the bottle, transfer the solution out of the bottle and filter it while hot using a Buchner funnel. Transfer the filtrate to the rotary evaporator bottle for further concentration. Repeat this concentration and crystallization process 5 times. Finally, place the reaction solution in the concentrated bottle in a rotary evaporator to concentrate it to a solid state. An orange to brown solid can be seen in the bottle, which is the polysulfide.

[0061] The sodium polysulfide prepared in this embodiment was sent to Science Compass Testing Company for molecular weight determination by dextran gel chromatography (GPC) and the Na and S content in sodium polysulfide was determined by ICP-OES / MS.

[0062] 1. GPC dextran gel chromatography was performed using an Agilent 1260 Infinity II chromatograph, with water as the mobile phase. The properties of sodium polysulfide were characterized, and the results are shown in Tables 4 and 5. Figure 2 .

[0063] Figure 2 This is the molecular weight distribution diagram of the polysulfide prepared by adding 5.5g of sublimed sulfur in Example 2. Figure 2 It can be seen that the sodium polysulfide prepared by sodium hypochlorite oxidation is mainly a mixture of two molecular weights, with weight-average molecular weights of 12373 g / mol and 4223 g / mol, respectively, and peak area percentages of 47.09% and 52.91%, respectively. The specific peak results and average weight-average molecular weights are shown in Tables 4 and 5, respectively.

[0064] Table 4 Peak Results

[0065]

[0066] Table 5 Average weight-average molecular weight

[0067]

[0068] GPC dextran gel permeation chromatography revealed that the sodium polysulfide prepared in this embodiment has a high degree of polymerization and is a polymer containing two molecular weights.

[0069] 2. The ICP-OES / MS determination method is the same as in Example 1, and the determination results are shown in Table 6.

[0070] Table 6

[0071]

[0072] As shown in Table 6, the mass ratio of S to Na in sodium polysulfide prepared using sodium hypochlorite is 0.6:1.

[0073] Product effectiveness test

[0074] 1. Using sodium polysulfide provided by the present invention to prepare ergothioneine (EGT), the polysulfides prepared in each example were studied, and the effect of commercially available polysulfides (Sigma-Aldrich) on the EGT yield was investigated.

[0075] Ergothioneine was prepared by reacting sodium polysulfide with TMH (histidine betaine) as a substrate under the catalysis of St enzyme (concentration of 4 g / L, amino acid sequence as shown in SEQ ID NO: 1, denoted as BZ006-DRN-1). The specific procedure was as follows:

[0076] (1) Prepare polysulfide solutions with a concentration of 200 g / L using the polysulfide (S:Na2S feed ratio 5.5:40) prepared in Examples 1-2 and commercially available polysulfide respectively. Adjust the pH to 9.0 with HCl. Sulfur will precipitate and the solution will become turbid. Filter the solution with a 0.22 μm filter to obtain a clear solution for later use. Then take 2 mL of polysulfide solution with a concentration of 200 g / L and 84 mL of TMH reaction solution (concentration of 51 mM) for each group, adjust the pH to 9 with 5 M HCl, and preheat at 30 °C to obtain the mixed solution of each group.

[0077] (2) 13.15 g of St enzyme (concentration 4 g / L, amino acid sequence as shown in SEQ ID NO: 1, designated as BZ006-DRN-1, enzyme loading 30.42 mg / g) was added to each group of mixtures. The pH was adjusted every 0.5 h to maintain it at 9.0. 2 mL of the corresponding 200 g / L polysulfide solution was added every 3 h of reaction, for a total of 7 additions. After the reaction was completed, ergothionein was obtained (the total reaction volume after 7 additions was 100 mL). Samples were taken at each time point of the reaction, and the EGT content was determined by liquid chromatography after diluting the solution 100 times with 50% acetonitrile water.

[0078] SEQ ID NO: 1: MKSISTDELLENLHRYKVIDIRSVDAYNGWKENGENR GGHIRSAKSLPYKWVNYIDWIEIVRSKDILPQDKLVIYGYDSEKAEEVARMFEKAGYTDLNIYPSFFEWVERNLPMDRLERYRHLVSPDWLNQLITTDNAPEYDNDKYVICHCHYRNPVDYEKGHIPGSIPLDTNSLESEDTWNRRSPEELKDALENAGISSETTVIVYGRFSYPKNDDPFPGSSAGHLGAMRCAFIML YAGVKDVRILNGGLQSWLDAGYNVTTEPAKISKVSFGANIPLNPKIAVDLEEAKEILSDPGKKLVSVRSWREYIGEVSGYNYIEKKGRIPGSVFGDCGTDAYHMENYRNLDHTMREYHEIEDKWKELGITPEKRNAFYCGTGWRGSEAFLNAWLMGWDNAAVFDGGWFEWSNNDLPFETGVPEK (Source Methanosalsum zhilinae).

[0079] Tests were conducted using the polysulfides provided in Examples 1 and 2 (S:Na2S feed ratio 5.5:40) and commercially available polysulfides (Sigma-Aldrich). The concentrations of EGT prepared were shown in Table 7. Figure 3 As shown.

[0080] Table 7

[0081]

[0082]

[0083] From Table 7 and Figure 3It can be seen that when preparing EGT using the polysulfides synthesized in Examples 1 and 2 of this invention, the EGT yields after 2 hours were 0.50 mmol / L and 0.21 mmol / L, respectively. When preparing EGT using commercially available sodium polysulfide from Sigma-Aldrich, the EGT yield after 2 hours was 0.44 mmol / L. As time progressed, at 23.5 hours, the EGT yields using the sodium polysulfide provided in Examples 1 and 2 were 0.91 mmol / L and 0.80 mmol / L, respectively. At this point, the EGT yield using commercially available sodium polysulfide from Sigma-Aldrich was only 0.48 mmol / L. The yields of EGT prepared using the sodium polysulfide provided in Examples 1 and 2 of this invention were higher than those prepared using the sodium polysulfide from Sigma-Aldrich, and the sodium polysulfide prepared by oxidation with hydrogen peroxide was superior to that prepared by oxidation with sodium hypochlorite.

[0084] 2. Using the sodium polysulfide provided by this invention to prepare ergothioneine (EGT), the effect of different feed ratios on the EGT yield was studied.

[0085] Sodium polysulfide prepared by adding 2.5, 5.5, and 11 g of sublimed sulfur in Examples 1 and 2, respectively, was used in the experiments, and the specific operating procedures were the same as above. The results are shown in Table 8.

[0086] Table 8

[0087]

[0088] As shown in Table 8, when the ratio of sublimed sulfur powder to sodium sulfide is 5.5:40, the synthesized sodium polysulfide has the highest yield of EGT.

[0089] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing a polysulfide, characterized in that, Includes the following steps: An oxidation reaction is carried out by adding a sulfide salt to an oxidant solution; then the temperature is raised to 50-80℃, and elemental sulfur is added while stirring to carry out a polymerization reaction; after the reaction is completed, crystallization is performed to obtain a polysulfide. The oxidant solution includes one of hydrogen peroxide solution, hypochlorous acid solution, or hypochlorite solution; During the addition of sulfide salts, the feeding rate needs to be controlled so that the temperature of the oxidation reaction does not exceed 35°C.

2. The preparation method according to claim 1, characterized in that, The hydrogen peroxide solution has a mass percentage of 0.2%-2%.

3. The preparation method according to claim 1, characterized in that, The hypochlorite solution is a sodium hypochlorite solution; the mass percentage of the sodium hypochlorite solution is 5%-20%.

4. The preparation method according to any one of claims 1-3, characterized in that, The mass ratio of elemental sulfur to the sulfide salt is (2-15):

40.

5. The preparation method according to any one of claims 4, characterized in that, The mass ratio of elemental sulfur to the sulfide salt is (4-9):

40.

6. The preparation method according to any one of claims 1-3, characterized in that, The polymerization reaction is carried out at a temperature of 50-80℃ for 1-5 hours.

7. A polysulfide, characterized in that, The polysulfide is prepared by any one of claims 1-6, wherein the polysulfide is a polymer with a single molecular weight or a mixture of two molecular weights.

8. The use of the polysulfide according to claim 7 in the preparation of ergothionein.

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