Selenium urea modified starch, and preparation method and application thereof

Abstract

The application discloses selenium urea modified starch, a preparation method and application thereof, and belongs to the technical field of chemical industry.The structure of the selenium urea modified starch is as follows: the average value range of n is 5-12000, and R is any one of the following structures:,, and.The selenium urea modified starch has the advantages that selenium urea groups are grafted into starch through a chemical method, the obtained selenium urea modified starch has good water solubility and excellent antioxidant activity, especially has an excellent scavenging effect on DPPH free radicals, and is a good antioxidant; the preparation method has fewer steps, consumes less time and energy, and has the feasibility of large-scale preparation.

Description

TECHNICAL FIELD

[0001] The present application relates to a modified starch and its preparation method and application, in particular to a selenium urea modified starch and its preparation method and application, and belongs to the technical field of chemical industry. BACKGROUND

[0002] Starch is a natural polymer compound widely existing in nature, which has good biocompatibility, but weak bioactivity and poor water solubility, resulting in low industrial application value.

[0003] Chemical modification can improve the bioactivity and water solubility of starch, and even endow starch with new functions. Chinese invention patent CN110028592A discloses an acetylated starch containing triazole quaternary ammonium salt and its preparation method and application. The acetylated starch containing triazole quaternary ammonium salt is prepared by introducing triazole and quaternary ammonium salt groups into the molecular structure of starch based on starch, and has excellent antioxidant activity and good water solubility. As shown in Tables 1, 2 and 3, the detection results show that the acetylated starch containing triazole quaternary ammonium salt has strong scavenging ability on superoxide anion free radicals (when the concentration is 0.1 mg / mL, the superoxide anion free radical scavenging rate is 100%), strong scavenging ability on hydroxyl radicals (when the concentration is 0.8 mg / mL, the hydroxyl radical scavenging rate is up to 90.52%), and slightly poor scavenging ability on DPPH free radicals (when the concentration is 1.6 mg / mL, the DPPH free radical scavenging rate is up to 88.24%).

[0004] However, the above patent still has some problems in the modification of starch, specifically:

[0005] (1) The acetylated starch containing triazole quaternary ammonium salt prepared has a DPPH free radical scavenging rate of only 88.24% at a concentration of 1.6 mg / mL, which still has room for further improvement.

[0006] (2) In the preparation of the acetylated starch containing triazole quaternary ammonium salt, chloroacetyl starch is synthesized from starch as raw material, and then azido acetylated starch (stirring at 80℃ for 8h), hydroxypropyl triazole-containing acetylated starch (reaction at 80℃ for 24h) and hydroxypropyl triazole quaternary ammonium salt-containing acetylated starch (reflux reaction for 36h) need to be further synthesized, which has more operation steps, longer time consumption, larger energy consumption and higher industrial production cost. SUMMARY

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a modified starch with good water solubility and excellent antioxidant activity, especially with excellent scavenging effect on DPPH free radicals. It also provides a method for preparing the aforementioned modified starch with fewer steps, shorter processing time, and lower energy consumption.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] Selenium urea-modified starch, the structure of which is shown below:

[0010]

[0011] Where n has an average value range of 5-12000, and R is any of the following structures:

[0012] , , .

[0013] The aforementioned method for preparing selenourea-modified starch includes the following steps:

[0014] (1) Chloroacetylated starch was prepared using starch and chloroacetyl chloride as raw materials;

[0015] (2) Dissolve the chloroacetylated starch obtained in step (1) in dimethyl sulfoxide, then add an organoselenourea compound, react at 60°C for 24 h, then precipitate with an appropriate amount of ethanol and wash and filter to obtain a filter cake, freeze dry to constant weight to obtain selenourea modified starch, wherein the organoselenourea compound is 1-phenyl-3-(pyridin-4-ylmethyl)selenourea, 1-(2-fluorophenyl)-3-(pyridin-4-ylmethyl)selenourea or 1-(3-chlorophenyl)-3-(pyridin-4-ylmethyl)selenourea.

[0016] Preferably, in step (1), the method for preparing chloroacetylated starch using starch and chloroacetyl chloride as raw materials is as follows: 1.00-1.61g of starch is weighed and dispersed in 20-30mL of deionized water, and the mixture is swollen and reacted at room temperature for 0.5h. Then, 0.75mL of chloroacetyl chloride is added, and the mixture is reacted at 30℃ for 12h. After that, the starch is precipitated with an appropriate amount of acetone or ethanol, and the filter cake is obtained by washing with ethanol and filtration. The filter cake is then freeze-dried to constant weight to obtain chloroacetylated starch.

[0017] Preferably, in step (2), the ratio of chloroacetylated starch to organoselenium urea compound is 1g:1.2-1.5g.

[0018] The aforementioned application of selenourea-modified starch in the preparation of antioxidants.

[0019] The advantages of this invention are:

[0020] (1) In this invention, selenourea groups are grafted into starch by chemical methods, which improves the antioxidant activity of starch. The selenourea modified starch prepared has excellent antioxidant activity, especially for DPPH free radicals. When the concentration of all selenourea modified starch is 1.6 mg / mL, the DPPH free radical scavenging rate reaches 99.98-100.00%, and when the concentration of some selenourea modified starch is 1.6 mg / mL, the hydroxyl free radical scavenging rate also reaches 100.00%. Both are excellent antioxidants and can be used in the fields of medicine, functional food health care, cosmetics, etc.

[0021] (2) The selenourea modified starch prepared by the present invention has good water solubility, with a solubility of more than 10 mg / mL in water, which lays the foundation for its industrial application.

[0022] (3) The method for preparing selenourea modified starch provided by the present invention can prepare modified starch with good water solubility and excellent antioxidant activity by synthesizing chloroacetyl starch with starch as raw material and then reacting it with an organic selenourea compound in one step. The whole preparation process has fewer steps, shorter time and less energy consumption, and is feasible for large-scale preparation. Attached Figure Description

[0023] Figure 1 It is the infrared spectrum of starch (raw material);

[0024] Figure 2 This is the 1H NMR spectrum of starch (raw material);

[0025] Figure 3 This is the infrared spectrum of the chloroacetylated starch prepared in Example 1;

[0026] Figure 4 This is the 1H NMR spectrum of the chloroacetylated starch prepared in Example 1;

[0027] Figure 5 This is the infrared spectrum of the 1-phenyl-3-(pyridin-4-ylmethyl)selenourea modified starch prepared in Example 1;

[0028] Figure 6 This is the 1H NMR spectrum of the 1-phenyl-3-(pyridin-4-ylmethyl)selenourea modified starch prepared in Example 1;

[0029] Figure 7 This is the infrared spectrum of 1-(2-fluorophenyl)-3-(pyridin-4-ylmethyl)selenourea modified starch prepared in Example 2;

[0030] Figure 8This is the 1H NMR spectrum of 1-(2-fluorophenyl)-3-(pyridin-4-ylmethyl)selenourea modified starch prepared in Example 2;

[0031] Figure 9 The infrared spectrum of 1-(2-chlorophenyl)-3-(pyridin-4-ylmethyl)selenourea modified starch prepared in Example 3 is shown.

[0032] Figure 10 This is the 1H NMR spectrum of 1-(2-chlorophenyl)-3-(pyridin-4-ylmethyl)selenourea modified starch prepared in Example 3;

[0033] Figure 11 The infrared spectrum of 1-(3-chlorophenyl)-3-(pyridin-4-ylmethyl)selenourea modified starch prepared in Example 4 is shown.

[0034] Figure 12 This is the 1H NMR spectrum of 1-(3-chlorophenyl)-3-(pyridin-4-ylmethyl)selenourea modified starch prepared in Example 4. Detailed Implementation

[0035] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0036] I. Structure of Selenium Urea Modified Starch

[0037] The structure of the selenium urea-modified starch provided by this invention is shown below:

[0038]

[0039] Where n has an average value range of 5-12000, and R is any of the following structures:

[0040] , , , .

[0041] II. Preparation method of selenium urea modified starch Example

[0042] .

[0043] Preparation method of 1-phenyl-3-(pyridin-4-ylmethyl)selenourea modified starch:

[0044] (1) Weigh 1.61g of starch (see infrared spectrum) Figure 1 The proton NMR spectrum is shown below. Figure 2The starch was dispersed in 30 mL of deionized water and allowed to swell at room temperature for 0.5 h. Then, 0.75 mL of chloroacetyl chloride was added, and the reaction was carried out at 30 °C for 12 h. After precipitation with an appropriate amount of ethanol, the starch was washed and filtered to obtain a filter cake. The filter cake was then freeze-dried to constant weight to obtain chloroacetylated starch. The infrared spectrum is shown in [reference needed]. Figure 3 The proton NMR spectrum is shown below. Figure 4 ;

[0045] (2) Weigh 1g of the chloroacetylated starch obtained in step (1) and dissolve it in 20mL of dimethyl sulfoxide. Then add 1.5g of 1-phenyl-3-(pyridin-4-ylmethyl)selenourea and react at 60℃ for 24h. After that, precipitate with an appropriate amount of ethanol, wash and filter to obtain filter cake. Freeze dry to constant weight to obtain 1-phenyl-3-(pyridin-4-ylmethyl)selenourea modified starch. The infrared spectrum is shown in [reference needed]. Figure 5 The proton NMR spectrum is shown below. Figure 6 .

[0046] Depend on Figure 3 It can be seen that, with starch (raw material), Figure 1 Compared to chloroacetylated starch, at 1746 cm⁻¹ -1 A vibrational absorption peak of the ester group appeared nearby, at 787 cm⁻¹. -1 Absorption vibration peaks of carbon-chlorine bonds appeared nearby.

[0047] Depend on Figure 4 It can be seen that, with starch (raw material), Figure 2 In contrast, chloroacetylated starch showed a proton peak of the methylene group in the chloroacetyl group around 4.3 ppm.

[0048] The above data indicates that the synthesis of chloroacetylated starch was successful.

[0049] Depend on Figure 5 It can be seen that at 1745cm -1 The vibrational absorption peak is still present at 1590 cm⁻¹. -1 A vibrational absorption peak of the selenurea group (-NH-CSe-NH-) appeared nearby, and at 766 cm⁻¹ -1 An absorption peak of the aromatic ring appeared nearby.

[0050] Depend on Figure 6 It can be seen that the proton absorption peaks of the benzene ring and pyridine ring in the selenourea group appear between 6.8 and 8.7 ppm.

[0051] The above data indicate that the 1-phenyl-3-(pyridin-4-ylmethyl)selenourea modified starch was successfully synthesized.

[0052] Example 2

[0053] .

[0054] Preparation method of 1-(2-fluorophenyl)-3-(pyridin-4-ylmethyl)selenourea modified starch:

[0055] (1) Weigh 1.00g of starch (see infrared spectrum) Figure 1 The proton NMR spectrum is shown below. Figure 2 Dispersed in 20 mL of deionized water, the mixture swelled at room temperature for 0.5 h, then 1.5 mL of chloroacetyl chloride was added, and the mixture was reacted at 30 °C for 12 h. After precipitation with an appropriate amount of acetone and washing with ethanol, the filter cake was obtained by vacuum filtration and freeze-drying to constant weight to obtain chloroacetylated starch.

[0056] (2) Weigh 1g of the chloroacetylated starch obtained in step (1) and dissolve it in 20mL of dimethyl sulfoxide. Then add 1.2g of 1-(2-fluorophenyl)-3-(pyridin-4-ylmethyl)selenourea and react at 60℃ for 24h. After that, precipitate with an appropriate amount of ethanol, wash and filter to obtain filter cake. Freeze dry to constant weight to obtain 1-(2-fluorophenyl)-3-(pyridin-4-ylmethyl)selenourea modified starch. The infrared spectrum is shown in [reference needed]. Figure 7 The proton NMR spectrum is shown below. Figure 8 .

[0057] Depend on Figure 7 It can be seen that at 1743cm -1 The vibrational absorption peak is still present at 1590 cm⁻¹. -1 A vibrational absorption peak of the selenurea group (-NH-CSe-NH-) appeared nearby, and at 762 cm⁻¹ -1 Nearby and 1492cm -1 An absorption peak of the aromatic ring appeared nearby.

[0058] Depend on Figure 8 It can be seen that the proton absorption peaks of the benzene ring and pyridine ring in the selenourea group appear between 7.0 and 8.8 ppm.

[0059] The above data indicate that the 1-(2-fluorophenyl)-3-(pyridin-4-ylmethyl)selenourea modified starch was successfully synthesized.

[0060] Example 3

[0061] .

[0062] Preparation method of 1-(2-chlorophenyl)-3-(pyridin-4-ylmethyl)selenourea modified starch:

[0063] (1) Chloroacetylated starch was prepared according to the method described in step (1) of Example 2;

[0064] (2) Weigh 1g of the chloroacetylated starch obtained in step (1) and dissolve it in 20mL of dimethyl sulfoxide. Then add 1.5g of 1-(2-chlorophenyl)-3-(pyridin-4-ylmethyl)selenourea and react at 60℃ for 24h. After that, precipitate with an appropriate amount of ethanol, wash and filter to obtain filter cake. Freeze dry to constant weight to obtain 1-(2-chlorophenyl)-3-(pyridin-4-ylmethyl)selenourea modified starch. The infrared spectrum is shown in the figure. Figure 9 The proton NMR spectrum is shown below. Figure 10 .

[0065] Depend on Figure 9 It can be seen that at 1731cm -1 The nearby vibrational absorption peak is still present at 1582 cm⁻¹. -1 A vibrational absorption peak of the selenurea group (-NH-CSe-NH-) appeared nearby, and at 765 cm⁻¹ -1 Nearby and 1469cm -1 An absorption peak of the aromatic ring appeared nearby.

[0066] Depend on Figure 10 It can be seen that the proton absorption peaks of the benzene ring and pyridine ring in the selenourea group appear between 6.9 and 8.8 ppm.

[0067] The above data indicate that 1-(2-chlorophenyl)-3-(pyridin-4-ylmethyl)selenourea modified starch was successfully synthesized.

[0068] Example 4

[0069] .

[0070] Preparation method of 1-(3-chlorophenyl)-3-(pyridin-4-ylmethyl)selenourea modified starch:

[0071] (1) Chloroacetylated starch was prepared according to the method described in step (1) of Example 2;

[0072] (2) Weigh 1g of the chloroacetylated starch obtained in step (1) and dissolve it in 20mL of dimethyl sulfoxide. Then add 1.5g of 1-(3-chlorophenyl)-3-(pyridin-4-ylmethyl)selenourea and react at 60℃ for 24h. After that, precipitate with an appropriate amount of ethanol, wash and filter to obtain filter cake. Freeze dry to constant weight to obtain 1-(3-chlorophenyl)-3-(pyridin-4-ylmethyl)selenourea modified starch. The infrared spectrum is shown in the figure. Figure 11 The proton NMR spectrum is shown below. Figure 12 .

[0073] Depend on Figure 11 It can be seen that at 1745cm -1 The nearby vibrational absorption peak is still present at 1584 cm⁻¹. -1A vibrational absorption peak for the selenurea group (-NH-CSe-NH-) appeared nearby, and at 781 cm⁻¹ -1 Nearby and 1468cm -1 An absorption peak of the aromatic ring appeared nearby.

[0074] Depend on Figure 12 It can be seen that the proton absorption peaks of the benzene ring and pyridine ring in the selenourea group appear between 6.9 and 8.8 ppm.

[0075] The above data indicate that the 1-(3-chlorophenyl)-3-(pyridin-4-ylmethyl)selenourea modified starch was successfully synthesized.

[0076] III. Determination of the antioxidant activity of selenourea-modified starch

[0077] Starch (raw material) Figure 1 ), chloroacetylated starch (prepared in step (1) of Example 1, Figure 2 ), 1-phenyl-3-(pyridin-4-ylmethyl)selenourea modified starch (prepared in Example 1, Figure 3 ), 1-(2-fluorophenyl)-3-(pyridin-4-ylmethyl)selenourea modified starch (prepared in Example 2), Figure 4 ), 1-(2-chlorophenyl)-3-(pyridin-4-ylmethyl)selenourea modified starch (prepared in Example 3), Figure 5 ) and 1-(3-chlorophenyl)-3-(pyridin-4-ylmethyl)selenourea modified starch (prepared in Example 4, Figure 6 After being freeze-dried to constant weight under vacuum, it is used as the sample to be tested.

[0078] 1. Determination of DPPH free radical scavenging ability

[0079] Each sample was prepared into a solution with concentrations of 0.3 mg / mL, 0.6 mg / mL, 1.2 mg / mL, 2.4 mg / mL, and 4.8 mg / mL using deionized water.

[0080] Sample group: Take 1 mL of the sample solution to be tested, add 2 mL of DPPH ethanol solution with a concentration of 0.036 mg / mL, mix well in a test tube, and the final concentration of the sample to be tested is 0.1 mg / mL, 0.2 mg / mL, 0.4 mg / mL, 0.8 mg / mL, and 1.6 mg / mL. Let stand at room temperature in the dark for 20 min, and then measure the absorbance at 517 nm.

[0081] Control group: No DPPH added. Specifically, take 1 mL of the sample solution to be tested, add 2 mL of anhydrous ethanol, mix well in a test tube, and the final concentration of the sample to be tested is 0.1 mg / mL, 0.2 mg / mL, 0.4 mg / mL, 0.8 mg / mL, and 1.6 mg / mL. Let stand at room temperature in the dark for 20 min, and then measure the absorbance at 517 nm.

[0082] Blank group: No test sample was added. Specifically, take 1 mL of deionized water, add 2 mL of 0.036 mg / mL DPPH ethanol solution, mix well in a test tube, let stand at room temperature in the dark for 20 min, and then measure the absorbance at 517 nm.

[0083] The absorbance of each sample was measured three times, and the average value was taken.

[0084] The formula for calculating the DPPH free radical scavenging ability of a sample is as follows:

[0085] DPPH radical scavenging capacity (%) = [1-(A 样品 -A 对照 ) / A 空白 ]×100%

[0086] Among them, A 样品 A represents the absorbance of the sample group. 对照 The absorbance of the control group, A 空白 The absorbance is for the blank group.

[0087] The results of the determination of the DPPH free radical scavenging ability (%) of each sample are shown in Table 1.

[0088] Table 1. Results of DPPH free radical scavenging ability (%) of each sample.

[0089]

[0090] 2. Determination of hydroxyl radical scavenging ability

[0091] Each sample was prepared into a stock solution with a concentration of 10 mg / mL using deionized water.

[0092] Sample groups: 45 μL, 90 μL, 180 μL, 360 μL, and 720 μL of sample stock solution were measured into test tubes, and deionized water was added to a final volume of 1 mL. Then, 0.5 mL of 0.556 mg / mL EDTA-Fe solution, 1 mL of pH 7.4 phosphate buffer, 1 mL of 0.36 mg / mL saffron red T solution, and 1 mL of 3% hydrogen peroxide solution were added sequentially. The final concentrations of the samples to be tested were 0.1 mg / mL, 0.2 mg / mL, 0.4 mg / mL, 0.8 mg / mL, and 1.6 mg / mL, respectively. The reaction system was then stoppered, shaken thoroughly, and reacted in a 37°C water bath for 30 min. After the reaction was complete, the reaction was quenched in ice water, and the absorbance of 4.5 mL of the reaction solution was measured and recorded at a wavelength of 520 nm.

[0093] Control group: No hydrogen peroxide was added. Specifically, 45 μL, 90 μL, 180 μL, 360 μL, and 720 μL of sample stock solution were measured into test tubes, respectively. Deionized water was added to a final volume of 1 mL. Then, 0.5 mL of 0.556 mg / mL EDTA-Fe solution, 2 mL of pH 7.4 phosphate buffer, and 1 mL of 0.36 mg / mL saffron T solution were added sequentially. The final concentrations of the test samples were 0.1 mg / mL, 0.2 mg / mL, 0.4 mg / mL, 0.8 mg / mL, and 1.6 mg / mL, respectively. The reaction system was then stoppered, shaken thoroughly, and reacted in a 37°C water bath for 30 min. After the reaction was complete, the reaction was quenched in ice water, and the absorbance of 4.5 mL of the reaction solution was measured and recorded at a wavelength of 520 nm.

[0094] Blank group: No sample was added. Specifically, 1 mL of deionized water, 0.5 mL of 0.556 mg / mL EDTA-Fe solution, 1 mL of pH 7.4 phosphate buffer, 1 mL of 0.36 mg / mL saffron T solution, and 1 mL of 3% hydrogen peroxide solution were added sequentially to a test tube. The reaction system was then stoppered, shaken thoroughly, and reacted in a 37°C water bath for 30 min. After the reaction was completed, the reaction was quenched in ice water, and the absorbance of 4.5 mL of the reaction solution was measured and recorded at a wavelength of 520 nm.

[0095] The absorbance of each sample was measured three times, and the average value was taken.

[0096] The formula for calculating the hydroxyl radical scavenging ability (scavenging rate) of a sample is as follows:

[0097] Clearance rate (%) = (A 样品 -A 空白 ) / (A 对照 -A 空白 ) × 100%

[0098] Among them, A 样品 A represents the absorbance of the sample group. 对照 The absorbance of the control group, A 空白 The absorbance is for the blank group.

[0099] The results of the determination of the scavenging ability (scavenging rate) of each sample are shown in Table 2.

[0100] Table 2. Results of the determination of hydroxyl radical scavenging ability (scavenging rate, %) of each sample.

[0101]

[0102] As shown in Tables 1 and 2, the modified starches 1-phenyl-3-(pyridin-4-ylmethyl)selenourea, 1-(2-fluorophenyl)-3-(pyridin-4-ylmethyl)selenourea, 1-(2-chlorophenyl)-3-(pyridin-4-ylmethyl)selenourea, and 1-(3-chlorophenyl)-3-(pyridin-4-ylmethyl)selenourea exhibit significantly enhanced DPPH free radical scavenging and hydroxyl free radical scavenging abilities (antioxidant activity) compared to starch and chloroacetylated starch.

[0103] IV. Water solubility test of selenourea-modified starch

[0104] Weigh 1g of 1-phenyl-3-(pyridin-4-ylmethyl)selenourea modified starch, 1-(2-fluorophenyl)-3-(pyridin-4-ylmethyl)selenourea modified starch, 1-(2-chlorophenyl)-3-(pyridin-4-ylmethyl)selenourea modified starch or 1-(3-chlorophenyl)-3-(pyridin-4-ylmethyl)selenourea modified starch, place them in a beaker, add 100mL of water, stir at room temperature, and observe the dissolution of each selenourea modified starch.

[0105] Observations showed that all the above-mentioned selenourea-modified starches were completely soluble at room temperature, with a solubility of over 10 mg / mL, and all exhibited good water solubility.

[0106] In summary, this invention introduces selenourea groups into starch through chemical modification, resulting in selenourea-modified starch with excellent antioxidant activity (especially excellent scavenging effect on DPPH free radicals) and good water solubility. It is a good antioxidant that can be applied in the fields of medicine, functional food and health care, and cosmetics.

[0107] It should be noted that the above embodiments are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is impossible to exhaustively list all possible implementations here. All obvious variations or modifications derived from the technical solutions of this invention are still within the scope of protection of this invention.

Claims

1. Selenium urea-modified starch, characterized in that, The structure of the selenium urea-modified starch is shown below: ， Where n has an average value range of 5-12000, and R is any of the following structures: 、 、 。 2. The method for preparing selenourea-modified starch according to claim 1, characterized in that, Includes the following steps: (1) Chloroacetylated starch was prepared using starch and chloroacetyl chloride as raw materials; (2) Dissolve the chloroacetylated starch obtained in step (1) in dimethyl sulfoxide, then add an organoselenourea compound, react at 60°C for 24 h, then precipitate with an appropriate amount of ethanol and wash and filter to obtain a filter cake, freeze dry to constant weight to obtain selenourea modified starch, wherein the organoselenourea compound is 1-phenyl-3-(pyridin-4-ylmethyl)selenourea, 1-(2-fluorophenyl)-3-(pyridin-4-ylmethyl)selenourea or 1-(3-chlorophenyl)-3-(pyridin-4-ylmethyl)selenourea; In step (1), the method for preparing chloroacetylated starch using starch and chloroacetyl chloride as raw materials is as follows: Weigh 1.00-1.61g of starch and disperse it in 20-30mL of deionized water. Allow it to swell at room temperature for 0.5h. Then add 0.75mL of chloroacetyl chloride and react at 30℃ for 12h. After precipitation with an appropriate amount of acetone or ethanol, wash with ethanol and filter to obtain filter cake. Freeze dry to constant weight to obtain chloroacetylated starch.

3. The method for preparing selenourea-modified starch according to claim 2, characterized in that, In step (2), the ratio of chloroacetylated starch to organoselurea compound is 1g:1.2-1.5g.

4. The application of the selenourea-modified starch according to claim 1 in the preparation of antioxidants.

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