Preparation method and application of amino salicylic acid xylan ester

Abstract

The invention discloses a preparation method and application of aminosalicylic acid xylan ester, and belongs to the technical field of glycan derivatives, the preparation method comprises the following steps: under the catalysis of diphenyl (2-hydroxyphenyl methyl) phosphine oxide, aminosalicylic acid and xylan are subjected to a reaction, and aminosalicylic acid modified xylan is prepared. In addition, the invention also provides an application of the aminosalicylic acid modified xylan in an animal breeding feed additive. According to the preparation method disclosed by the invention, the diphenyl (2-hydroxyphenylmethyl) phosphine oxide is utilized for catalysis, so that the aminosalicylic acid and the xylan are subjected to substitution reaction, complex functional group protection is not needed, and the yield and the purity are good; in the application of animal breeding feed, the modified product is added into the feed, so that the growth performance of bred animals such as chickens and the like can be remarkably improved, the intestinal morphology can be improved, and an efficient, simple and convenient preparation and application scheme is provided for feed additives.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of polysaccharide derivatives, and particularly to a preparation method of amino salicylic acid xylan ester and its application. BACKGROUND

[0002] Xylan is a kind of hemicellulose widely existing in plant cell walls, which is formed by the connection of xylose through β-1, 4-glucoside bond. Xylan is extremely rich in sources, and forestry resources, forestry and agricultural wastes are reliable sources of xylan. The content of xylan in corn cob is as high as 35%-40%, the content of xylan in bagasse is 24%-28%, and the content of xylan in cotton seed shell is 24%-32%. In addition, wood such as birch is also a source of xylan, and xylan can be extracted synchronously in the process of wood processing, reducing resource waste.

[0003] Xylan has been utilized in many fields. In the field of feed, xylan has been proved to be decomposed and utilized by specific microorganisms in the intestinal tract of animals due to its unique physicochemical properties and biological activity, and the generated oligoxylan fragments can regulate intestinal microecology, promote the proliferation of beneficial bacteria and inhibit the colonization of harmful bacteria, thereby improving the digestion and absorption efficiency of nutrients and enhancing the immunity of animals, which has attracted much attention in livestock and aquaculture.

[0004] At present, when xylan is used as a feed additive, it is mostly in the form of simple physical compounding, that is, xylan is mixed with other prebiotics, vitamins, minerals and the like. However, the structure of xylan itself is not modified, and the regulation effect on intestinal flora is limited by the natural structure, and the synergistic or antagonistic effect between different components is difficult to control, which affects the improvement effect on animal growth performance. Moreover, compounding increases the production links and cost, and the stability of each component is easily affected by the environment during storage and transportation, resulting in stratification and degradation and reducing the product efficacy. Therefore, it is urgent to develop xylan derivatives with single efficient functional structure without complex compounding.

[0005] Amino salicylic acid has the potential to regulate biological activity and target due to the functional groups such as amino, phenolic hydroxyl and carboxyl. The ester compound modified by amino salicylic acid is obtained by esterification between the carboxyl in amino salicylic acid and the hydroxyl in sugar substances, but the esterification reaction between the existing sugar substances and amino salicylic acid is prone to occur randomly at different hydroxyl sites, and it is difficult to realize the modification of specific sites and specific structures. At the same time, the functional groups such as amino and phenolic hydroxyl in amino salicylic acid are prone to side reactions with reagents in the reaction system, which interferes with the esterification process. In order to solve these problems, the traditional method needs to perform complex functional group protection operation on the non-targeted hydroxyl of sugar and the non-reactive functional groups of amino salicylic acid, and an additional step is needed to remove the protection group after the reaction is completed. This not only increases the reaction steps and reagent cost, prolongs the production cycle, but also produces by-products due to the introduction and removal process of the protection group, which reduces the yield and purity of the target product. SUMMARY

[0006] The present application aims to provide a preparation method of amino salicylic acid xylan ester, and overcome the defects of xylan needing to be compounded when added in feed, and provide an application of the amino salicylic acid xylan ester in feed additives.

[0007] To achieve the above-mentioned purpose, the technical scheme of the present application is:

[0008] Firstly, the present application provides a preparation method of amino salicylic acid xylan ester, comprising the following steps: under the catalysis of diphenyl(2-hydroxyphenylmethyl) phosphine oxide, amino salicylic acid reacts with xylan to prepare amino acid xylan ester.

[0009] The reaction process is shown in formula (1):

[0010]

[0011] In formula (1), n≥10.

[0012] By introducing diphenyl(2-hydroxyphenylmethyl) phosphine oxide, efficient preparation of amino salicylic acid xylan ester is realized, the generation of by-products is inhibited, and the yield of the product is improved.

[0013] The reaction mechanism of the reaction is shown in formula (2):

[0014]

[0015] In formula (2), n≥10.

[0016] In the reaction, diphenyl(2-hydroxyphenylmethyl) phosphine oxide first dehydrates and condenses with amino salicylic acid to form a phosphorus-containing active intermediate. The intermediate uses the electrophilic property of the phosphorus atom to guide the nucleophilic attack of xylan hydroxyl, realizing the activation and modification of xylan hydroxyl. Subsequently, through dynamic reconstruction of phosphorus-oxygen bond, the amino salicylic acid derivative structure is connected to the xylan chain by ester bond, and after the reaction, the phosphine oxide is separated to enter the next round of catalytic cycle, promoting the preparation of amino salicylic acid xylan ester, without the need for complex functional group protection.

[0017] In an embodiment, the amino salicylic acid is one of 5-amino salicylic acid or 4-amino salicylic acid.

[0018] In an embodiment, the mass ratio of the xylan to the amino salicylic acid is 1:(1.5-3.0).

[0019] In an embodiment, the molar ratio of aminosalicylic acid to diphenyl(2-hydroxyphenylmethyl)phosphine oxide is (20-30):1.

[0020] In an embodiment, the step comprises: adding xylan, aminosalicylic acid and catalyst into an organic solvent, and performing reaction under the condition of refluxing water separation; after the reaction is completed, removing the organic solvent, and purifying the solid to obtain aminosalicylic acid xylan ester.

[0021] In an embodiment, the organic solvent is one or more of 1,4-dioxane, cyclohexane or toluene.

[0022] In an embodiment, the purification step comprises: placing the solid in a centrifuge tube, adding saturated sodium bicarbonate solution for vortex washing, centrifuging, and drying after discarding the water layer.

[0023] Secondly, the application further provides an application of aminosalicylic acid xylan ester, wherein the aminosalicylic acid xylan ester prepared by any one of the preparation methods described above is added to animal feed.

[0024] In summary, the preparation method of the application utilizes diphenyl(2-hydroxyphenylmethyl)phosphine oxide catalysis to enable aminosalicylic acid to react with xylan through Mitsunobu substitution reaction without complex functional group protection, and high-efficiency preparation of aminosalicylic acid xylan ester is achieved through refluxing water separation and simple post-treatment, with good yield and purity; in animal breeding feed application, the modified product added to the feed can significantly improve the growth performance of breeding animals such as chickens and improve the intestinal morphology, and compared with direct addition of xylan or xylan-prebiotic compound, it exhibits more optimal or similar application effect, thereby providing an efficient and simple preparation and application scheme for feed additives.

[0025] In order to make the above features and advantages of the application more obvious and easy to understand, the following embodiments are described in detail as follows. DETAILED DESCRIPTION

[0026] In order to make the above features and advantages of the application more obvious and easy to understand, the following embodiments are described in detail as follows.

[0027] In the following examples and comparative examples, all reagents and consumables are purchased from conventional reagent manufacturers in the art unless otherwise specified; and the experimental methods and technical means used are conventional methods and means in the art unless otherwise specified.

[0028] Example 1:

[0029] The present example provides a preparation method of amino salicylic acid xylan ester, comprising the steps of:

[0030] In a round-bottom flask, xylan 1.0 g, 5-amino salicylic acid 1.5 g and diphenyl(2-hydroxyphenylmethyl) phosphine oxide 0.05 mol were added, and 1,4-dioxane 20 mL was added. Then the round-bottom flask was connected with a Dean-Stark trap (with activated molecular sieve inside) and refluxed for 20 hours. After the reaction was completed, 1,4-dioxane was removed by rotary evaporation. The product was purified, the obtained solid was placed in a centrifuge tube, 5 mL of saturated sodium bicarbonate solution was added and vortexed, centrifuged (3000 r / min, 5 min), and the water layer was discarded; the above purification operation was repeated 2 times, and then dried to obtain 0.85 g of light yellow solid, which was amino salicylic acid modified xylan, recorded as product A, and the yield of A was 70.80%.

[0031] Example 2:

[0032] The present example provides a preparation method of amino salicylic acid xylan ester, comprising the steps of:

[0033] In a round-bottom flask, xylan 1.0 g, 5-amino salicylic acid 2.0 g and diphenyl(2-hydroxyphenylmethyl) phosphine oxide 0.06 mol were added, and 1,4-dioxane 20 mL was added. Then the round-bottom flask was connected with a Dean-Stark trap (with activated molecular sieve inside) and refluxed for 20 hours. After the reaction was completed, 1,4-dioxane was removed by rotary evaporation. The product was purified, the obtained solid was placed in a centrifuge tube, 5 mL of saturated sodium bicarbonate solution was added and vortexed, centrifuged (3000 r / min, 5 min), and the water layer was discarded; the above purification operation was repeated 2 times, and then dried to obtain 0.95 g of light yellow solid, which was amino salicylic acid modified xylan, recorded as product B, and the yield of B was 73.08%

[0034] Example 3:

[0035] The present example provides a preparation method of amino salicylic acid xylan ester, comprising the steps of:

[0036] In a round bottom flask, add xylan 1.0 g, 5-amino salicylic acid 3.0 g and diphenyl(2-hydroxyphenylmethyl)phosphine oxide 0.075 mol, add 1,4-dioxane 20 mL. Then connect the round bottom flask with Dean-Stark trap (put activated molecular sieve inside), reflux for 20 hours. After the reaction is completed, remove 1,4-dioxane by rotary evaporation. Purify the product, put the obtained solid into a centrifuge tube, add saturated sodium bicarbonate solution 5 mL, vortex, centrifuge (3000 r / min, 5 min), discard the water layer; repeat the above purification operation 2 times, and dry to obtain 0.95 g of light yellow solid, which is the amino salicylic acid modified xylan, recorded as product C, the yield of C is 63.33%

[0037] Comparative Example 1:

[0038] The difference between this comparative example and Example 1 is only that no diphenyl(2-hydroxyphenylmethyl)phosphine oxide is added, and the product prepared is recorded as D, and the yield of D is 25.36%.

[0039] Comparative Example 2:

[0040] The difference between this comparative example and Example 1 is only that the catalyst added is p-toluenesulfonic acid, and the product prepared is recorded as E, and the yield of E is 45.28%.

[0041] Comparative Example 3:

[0042] The difference between this comparative example and Example 1 is only that the catalyst added is 0.5% dilute sulfuric acid, and the product prepared is recorded as F, and the yield of F is 48.95%.

[0043] From the product yield in Examples 1-3 and Comparative Examples 1-3, it can be seen that by introducing diphenyl(2-hydroxyphenylmethyl)phosphine oxide, efficient preparation of amino salicylic acid modified xylan is achieved, and compared with no catalyst (Comparative Example 1) and adding common esterification reaction catalyst (Comparative Examples 2-3), the yield of xylan ester is obviously improved.

[0044] Comparative Example 4:

[0045] This comparative example is used for subsequent verification experiments, and the provided compound only includes xylan, recorded as compound G.

[0046] Comparative Example 5:

[0047] This comparative example is used for subsequent verification experiments, and the provided compound is a compound of xylan and fructooligosaccharide, and the ratio of xylan to fructooligosaccharide is 1:1, recorded as compound H.

[0048] Verification Experiment:

[0049] The products / compounds provided in the above Examples 1-3 and Comparative Examples 4-5 were used in broiler growth experiments, respectively.

[0050] 1. Experimental animals:

[0051] 180 healthy white-feather broilers of 1-day-old were selected, and the body weights were kept uniform. After detection, the initial body weight was 42 ± 2 g. The broilers were randomly divided into 6 groups, namely Group 1 to Group 6, with 30 broilers in each group and 3 replicates in each group. The feeding period was 42 days. The feeding environment was kept uniform in temperature (32-35℃ for 1-7 days old, and then decreased by 3℃ per week to 25℃), humidity (60%-65%), and illumination (24h illumination for 1-3 days old, and then 16h illumination + 8h darkness). The broilers were allowed to freely eat and drink.

[0052] 2. Experimental feed:

[0053] The experimental feed included a basic feed and an additive feed. The basic feed was a feed formula designed with reference to the Poultry Feeding Standard (NY / T 33-2004) of the People's Republic of China, with corn and soybean meal as main raw materials. Specifically, the basic feed included corn 60%, soybean meal 25%, fish meal 5%, vegetable oil 3%, stone powder 2%, calcium hydrogen phosphate 2%, and premix 3%.

[0054] The additive feed was Product A provided in Example 1, Product B provided in Example 2, Product C provided in Example 3, Compound G provided in Comparative Example 4, and Compound H provided in Comparative Example 5, respectively.

[0055] The basic feed and the additive feed were configured into 6 groups of experimental feed, respectively.

[0056] Table 1. Configuration table of experimental feed

[0057]

[0058]

[0059] In the table, 0.5% means that the mass of the additive feed accounts for 0.5% of the mass of the basic feed.

[0060] 3. Feeding management:

[0061] The feed intake of each group of broilers was recorded daily. The health status of the broilers was observed, and the manure was cleaned in time to keep the coop clean. The number of dead and sick broilers was recorded in time, and the seriously unqualified ones were culled. The weight of the dead broilers was recorded in time, and the feed consumption of the cage was deducted.

[0062] Immunization program: the broilers were inoculated with newcastle disease vaccine by drinking water method for one week, inoculated with IB vaccine by drinking water method after two weeks, inoculated with newcastle disease vaccine by drinking water method again at three weeks; at 28 days of age, IB vaccine was inoculated again by drinking water method to prevent IB of broilers; the feeding period was 42 days.

[0063] 4. Index detection:

[0064] At 42 days of age, 6 chickens were randomly selected from each group, i.e. 2 chickens were selected from each repeated group, and the body weight was weighed. The chickens were sacrificed by neck vein bloodletting, and the intestinal contents were separated for intestinal flora detection; the jejunum tissue was taken for villus height and crypt depth determination.

[0065] 5. Experimental results:

[0066] (1) Growth performance (42 days of age) detection

[0067] Correlation index calculation method:

[0068] Average daily feed intake (ADFI) = total feed consumption / (test days x number of chickens).

[0069] Average daily gain (ADG) = (final weight / final number of chickens - initial weight / initial number of chickens) / test days.

[0070] Feed conversion ratio (FCR) = average daily feed intake (ADFI) / average daily gain (ADF).

[0071] The detection results are shown in Table 2:

[0072] Table 2 Growth performance experimental results

[0073]

[0074]

[0075] From the above table data, it can be seen that the average daily gain of Comparative Example 5 (group 5: xylan and fructooligosaccharide compound) is the highest, the feed conversion ratio is the lowest, and the growth performance is the best; the average daily gain of the example groups (groups 1-3) is significantly higher than that of Comparative Example 4 (group 4) and the control group (group 6, P<0.05), slightly lower than that of Comparative Example 5, and the difference is small; the growth performance of Comparative Example 4 and the control group is relatively poor. This shows that the xylan modified by aminosalicylic acid has better performance in promoting the growth of broilers.

[0076] (2) Intestinal morphology index detection

[0077] The normal structure and function of the intestinal tract is the basic guarantee for the sufficient digestion and absorption of nutrients, especially the intestinal villus height, crypt depth and V / C ratio are important indicators for measuring the digestion and absorption function of the intestinal tract. The villus height is significantly correlated with the cell number, and in the finger-like villus, the height of the villus is related to the number of intestinal epithelial cells. When the villus becomes longer, the number of intestinal epithelial cells increases; when the villus becomes shorter, the number of mature intestinal epithelial cells decreases, and the absorption capacity is low. The crypt depth reflects the cell generation rate, and the cells continuously migrate and differentiate from the base of the crypt to the end of the villus to replenish the normal shedding of the villus epithelium. Therefore, the crypt can be regarded as a processing plant for the villus. If this process slows down, the cell generation rate at the base decreases, and the crypt becomes shallow. The shallower crypt indicates that the maturation rate of intestinal epithelial cells increases, and the absorption function is enhanced. The deeper crypt indicates that the tissue metabolism accelerates and the increase of new tissue is needed, which means that the required nutrients for maintenance increase, and the animal production efficiency decreases. The VH / CD ratio reflects the functional state of the intestinal tract. The ratio increases, and the mucosa is improved, the digestion and absorption function is enhanced, and the growth and development is accelerated; the ratio decreases, and the mucosa is damaged, the digestion and absorption function is reduced.

[0078] The detection results of the intestinal morphology (jejunum) are shown in Table 3:

[0079] Table 3 Detection results of intestinal morphology

[0080]

[0081]

[0082] The villus height of the comparative example 5 (group 5: xylan and fructooligosaccharide compound) is the highest, the crypt depth is the shallowest, the VH / CD ratio is the largest, the intestinal morphology is the best, and the nutrient absorption capacity is the strongest; the intestinal morphology indexes of the example groups (groups 1-3) are significantly better than those of the comparative example 4 (group 4) and the control group (group 6, P<0.05). It is indicated that the xylan modified by aminosalicylic acid can well improve the intestinal morphology of broilers.

[0083] In summary, in the present experiment, white-feathered broilers are taken as the objects, and the effect of the xylan modified by aminosalicylic acid as a feed additive is verified. The results show that the xylan modified by aminosalicylic acid group is significantly better than the direct addition of xylan group, and the product B of the example 2 has a relatively better effect as an additive. It is indicated that the xylan modified by aminosalicylic acid can be applied as an effective feed additive in animal breeding, and more possibilities are provided for the selection of feed additives.

[0084] Although the present application has been illustrated and described in detail by preferred embodiments in the foregoing, the present application is not limited to the disclosed examples, and other variants can be derived therefrom by those skilled in the art without departing from the scope of protection of the present application.

Claims

1. A process for the preparation of amino salicylic xylan ester, characterized by, The method comprises the following steps: The amino salicylic acid xylan ester is prepared by reacting amino salicylic acid with xylan under the catalysis of diphenyl(2-hydroxyphenylmethyl)phosphine oxide.

2. A process for the preparation of amino salicylic xylan ester according to claim 1, characterized in that, The amino salicylic acid is one of 5-amino salicylic acid and 4-amino salicylic acid.

3. A process for the preparation of amino salicylic xylan ester according to claim 2, characterized in that, The mass ratio of the xylan to the amino salicylic acid is 1:(1.5-3.0).

4. A process for the preparation of amino salicylic xylan ester according to claim 3, characterized in that, The molar ratio of the amino salicylic acid to the diphenyl(2-hydroxyphenylmethyl)phosphine oxide is (20-30):

1.

5. The process for the preparation of amino salicylic xylan ester as claimed in claim 1, wherein, The step comprises: adding the xylan, the amino salicylic acid and the catalyst into an organic solvent, and reacting under the condition of refluxing and water separation; after the reaction is completed, the organic solvent is removed, and the solid is purified to obtain the amino salicylic acid xylan ester.

6. A process for the preparation of amino salicylic xylan ester according to claim 5, characterized in that, The organic solvent is one or more of 1,4-dioxane, cyclohexane and toluene.

7. A process for the preparation of amino salicylic xylan ester according to claim 6, characterized in that, The purification step comprises: placing the solid into a centrifugal tube, adding saturated sodium bicarbonate solution for vortex washing, centrifuging, discarding the water layer and drying.

8. Use of an aminosalicylic acid xylan ester, characterized in that The amino salicylic acid modified xylan prepared by the preparation method in any one of claims 1-7 is added into animal feed.

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