Short-chain fatty acid ester as well as preparation method and application thereof

Abstract

The invention provides short-chain fatty acid ester as well as a preparation method and application thereof. The preparation method comprises the following steps: mixing short-chain fatty acid, glycerol and a catalyst, and reacting under heating and stirring; after the reaction is finished, taking out reaction liquid, and removing the catalyst to obtain a short-chain fatty acid ester crude product; and separating to obtain a short-chain fatty acid ester pure product. The short-chain fatty acid is butyric acid or propionic acid, and the obtained short-chain fatty acid ester is tributyrin or glyceryl tripropionate. The method uses the acidic ionic liquid or solid acid as the catalyst to catalyze the reaction of butyric acid or propionic acid and glycerol under certain conditions to synthesize tributyrin and glycerol tripropionate, has the advantages of high conversion rate, short time consumption, simple process operation, easy separation, environmental protection and the like, and is good in safety, high in yield, low in cost and suitable for industrial production. The industrial production of the tributyrin and the glyceryl tripropionate is facilitated. The short-chain fatty acid ester is applied to preparation of food, medicine or feed for relieving colitis, and the relieving effect on colitis is good.

Description

Technical Field

[0001] The present invention belongs to the technical fields of food, medicine, and feed, and particularly relates to a short-chain fatty acid ester, a preparation method thereof, and uses thereof. Background Art

[0002] In recent years, due to reasons such as irregular work and rest and eating patterns, colitis resulting therefrom has gradually developed into a new type of global intestinal inflammatory disease. It has a long course, is difficult to cure completely, and drug treatment is often accompanied by many side effects. Although its pathogenesis has not been fully clarified, genetics, environment, immune system, and intestinal flora have all been proven to be related thereto. Intestinal homeostasis imbalance, especially changes in the composition of intestinal flora and metabolic disorders, is an important feature of colitis. Propionic acid and butyric acid, as the energy source of colonic epithelial cells and intestinal homeostasis regulators, are important components for relieving colitis. However, propionic acid and butyric acid have strong pungent odors, are volatile, highly corrosive, and are easily absorbed in the upper digestive tract, and have almost no effect on relieving colitis. Synthesizing their corresponding derivatives can overcome these deficiencies.

[0003] Tributyrin and tripropionin are short-chain fatty acid esters, which are the esterification products of butyric acid or propionic acid and glycerol respectively. At present, although there are studies attempting to synthesize tributyrin, there are generally deficiencies such as low conversion efficiency, incomplete reaction, many intermediate products (such as monobutyryl / propionyl glycerol, dibutyryl / propionyl glycerol), and difficult separation. Tributyrin and tripropionin have broad application prospects, and there is an urgent need to develop a simple, efficient, and safe preparation method for tributyrin and tripropionin. Summary of the Invention

[0004] In view of the above technical problems, the present invention provides a short-chain fatty acid ester and a preparation method thereof. This method uses an acidic ionic liquid or a solid acid as a catalyst to catalyze the reaction of butyric acid or propionic acid with glycerol to synthesize tributyrin and tripropionin under certain conditions, and has the advantages of high conversion rate (≥90%), short time consumption, simple process operation, easy separation, no pungent odor, environmental friendliness, etc. It has good safety, high yield (≥90%), and low cost, which is conducive to the industrial production of tributyrin and tripropionin.

[0005] The present invention also provides a use of the short-chain fatty acid ester, which is an application of the short-chain fatty acid ester prepared by the method in the preparation of food, medicine, or feed for relieving colitis. The tributyrin and tripropionin have good effects on relieving colitis.

[0006] Note that the recitation of these objects does not preclude the existence of other objects. One aspect of the present invention does not need to achieve all of the above objects. Objects other than the above can be extracted from the descriptions in the specification, drawings, and claims.

[0007] The present invention achieves the above technical objectives through the following technical means.

[0008] A preparation method of short-chain fatty acid esters, comprising the following steps:

[0009] Step S1, mixing short-chain fatty acids, glycerol and a catalyst, and reacting under heating and stirring;

[0010] Step S2, after the reaction ends, taking out the reaction solution, removing the catalyst, and obtaining a crude product of short-chain fatty acid esters;

[0011] Step S3, separating to obtain pure short-chain fatty acid esters.

[0012] In the above solution, the short-chain fatty acid in step S1 is butyric acid or propionic acid.

[0013] In the above solution, the catalyst in step S1 is an acidic ionic liquid or a solid acid.

[0014] Further, the acidic ionic liquid is one of 1-sulfobutyl-3-methylimidazolium hydrochloride, 1-sulfobutyl-3-methylimidazolium hydrogen sulfate, and 1-sulfobutyl-3-methylimidazolium trifluoromethanesulfonate.

[0015] Further, the solid acid is Amberlyst 15 or HND-580.

[0016] In the above solution, the molar ratio of glycerol to short-chain fatty acids in step S1 is 1:3 to 1:100; the catalyst addition amount is 0.1% to 10% (w / w) of the sum of the substrate masses; the reaction temperature is 80°C to 150°C, and the reaction time is 0.5 h to 12 h.

[0017] Further, the molar ratio of glycerol to short-chain fatty acids is 1:3 to 1:30; the catalyst addition amount is 0.5% to 5% (w / w) of the sum of the substrate masses; the reaction temperature is 90°C to 140°C, and the reaction time is 1 h to 10 h.

[0018] In the above solution, the short-chain fatty acid ester is tributyrin or tripropionin.

[0019] A short-chain fatty acid ester prepared according to the preparation method of the short-chain fatty acid ester.

[0020] A use of a short-chain fatty acid ester, the application of the short-chain fatty acid ester in the preparation of foods, medicines or feeds for alleviating colitis. Specifically, the application of tributyrin or tripropionin in the preparation of foods, medicines or feeds for alleviating colitis.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] The present invention provides a method for preparing short-chain fatty acid esters. The short-chain fatty acid is butyric acid or propionic acid, and tributyrin or tripropionin is prepared by this method. This method does not require the additional addition of a reaction solvent and has the advantages of high conversion rate (≥90%), short time consumption (6h - 48h), simple process operation, low energy consumption, easy separation, mild reaction conditions, environmental friendliness, and no odor. The obtained tributyrin and tripropionin products have good safety, high yield (≥90%), and low cost, which is beneficial to industrial production and is of great significance for improving the industrial production level of tributyrin and tripropionin.

[0023] Note that the description of these effects does not prevent the existence of other effects. One embodiment of the present invention does not necessarily have all of the above effects. Effects other than the above can be obviously seen and extracted from the descriptions in the specification, drawings, claims, etc. Description of the Drawings

[0024] Figure 1 It is a reaction formula and product analysis diagram of the method for preparing short-chain fatty acid esters in Example 1 of the present invention, wherein Figure 1 A is the synthesis reaction formula of tributyrin, Figure 1 B is the liquid chromatography diagram, Figure 1 C is the infrared spectrum diagram, Figure 1 D is the mass spectrum diagram, Figure 1 E is of the new product 1 1H nuclear magnetic resonance spectrum diagram, Figure 1 F is of the new product 13 13C NMR nuclear magnetic resonance spectrum diagram.

[0025] Figure 2 It is a reaction formula and product analysis diagram of the method for preparing short-chain fatty acid esters in Example 5 of the present invention, wherein Figure 2 A is the synthesis reaction formula of tripropionin, Figure 2 B is the liquid chromatography diagram, Figure 2 C is the infrared spectrum diagram, Figure 2 D is the mass spectrum diagram, Figure 2 E is of the new product 1 1H nuclear magnetic resonance spectrum diagram, Figure 2 F is of the new product 13 13C NMR nuclear magnetic resonance spectrum diagram.

[0026] Figure 3 It is an index analysis diagram of tributyrin and tripropionin on DSS-induced colitis in mice in Example 9 of the present invention, wherein Figure 3 A is the body weight change, Figure 3 B is the DAI score, Figure 3 C is the typical colon appearance, Figure 3D is the statistical data of colon length, Figure 3 E is the pathological section of colon tissue, Figure 3 F is the score of colon tissue. Specific implementation mode

[0027] The present invention will be further described below in conjunction with specific embodiments. These embodiments are only for the purpose of explanation and do not limit the scope and essence of the present invention. The experimental methods used in the following embodiments are all conventional methods unless otherwise specified; the reagents, materials, etc. used in the following embodiments can be obtained from commercial channels unless otherwise specified.

[0028] A preparation method of short-chain fatty acid ester, comprising the following steps:

[0029] Step S1: Weigh short-chain fatty acid, glycerol and catalyst into a reaction flask respectively, and react under heating and stirring;

[0030] Step S2: After the reaction is completed, take out the reaction solution, remove the catalyst, and obtain the crude short-chain fatty acid ester;

[0031] Step S3: Separate to obtain the pure short-chain fatty acid ester.

[0032] The short-chain fatty acid in step S1 is butyric acid or propionic acid.

[0033] The catalyst in step S1 is an acidic ionic liquid or a solid acid.

[0034] The acidic ionic liquid is one of 1-sulfobutyl-3-methylimidazolium hydrochloride, 1-sulfobutyl-3-methylimidazolium hydrogensulfate, and 1-sulfobutyl-3-methylimidazolium trifluoromethanesulfonate.

[0035] The solid acid is Amberlyst 15 or HND-580.

[0036] The molar ratio of glycerol to short-chain fatty acid is 1:1 to 1:100, the catalyst addition amount is 0.1% to 10% (w / w) of the total mass of the substrates, the reaction temperature is 80°C to 150°C, and the reaction time is 0.5 h to 12 h.

[0037] Preferably, the molar ratio of glycerol to short-chain fatty acid is 1:3 to 1:50, the catalyst addition amount is 0.5% to 5% (w / w) of the total mass of the substrates, the reaction temperature is 90°C to 140°C, and the reaction time is 1 h to 10 h.

[0038] The short-chain fatty acid ester is tributyrin or tripropionin.

[0039] A short-chain fatty acid ester prepared according to the preparation method of the short-chain fatty acid ester.

[0040] Use of a short-chain fatty acid ester, application of the short-chain fatty acid ester in the preparation of foods, medicines or feeds for relieving colitis, specifically application of tributyrin or tributyrin in the preparation of foods, medicines or feeds for relieving colitis.

[0041] Product separation: After the reaction is completed, take out the reaction solution, add water and ethyl acetate, collect the ethyl acetate layer, and remove the solvent by rotary evaporation to obtain the pure product of the product.

[0042] Liquid chromatography analysis (HPLC): Take 100 μL of the reaction solution, dilute it with 1 mL of absolute ethanol, and filter it through a 0.45 μm microporous membrane. Use an LC-20AD type high performance liquid chromatograph, Symmetry C 18 chromatographic column (5 μm, 4.6 mm × 250 mm, Waters), control the column temperature at 35 °C, the injection volume is 10 μL, the mobile phase is acetonitrile / water (4:1, v / v), and the flow rate is 1.0 mL / min. Select a ZAM4000 type evaporative light scattering detector as the detector, use nitrogen as the carrier gas, the pressure is 0.6 bar, and control the detector temperature at 70 °C.

[0043] Mass spectrometry analysis (MS): Use a WatersXevo G2-XS QTof high resolution mass spectrometry combined instrument, the injection volume is 1 μL, and the ionization method uses electrospray positive ion mode (ESI + ), the capillary voltage is 3.5 KV, the ion source temperature is 100 °C, the desolvation temperature is 250 °C, the desolvation gas flow rate is 500 L / h, the cone hole gas flow rate is 50 L / h, the cone hole voltage is 20 V, the collision energy is 6 V, the detector voltage is 1700 V, and the mass range is 100 - 400 m / z.

[0044] Fourier transform infrared spectroscopy analysis (FT-IR): The instrument model is Nicolet iS 50, use the attenuated total reflection method (ATR), the scanning range is 600 - 4000 cm -1 , the number of scanning times is 32 times, the number of background scanning times is 32 times, the resolution is 4 cm -1 , the sampling gain is 1, the moving mirror speed is 0.4747, and the aperture setting is 100.

[0045] Nuclear magnetic resonance spectroscopy analysis (NMR): The instrument model is Bruker 400Ultrashield TM superconducting nuclear magnetic resonance spectrometer, using deuterated chloroform as the solvent, 1 H and 13 C spectrum frequencies are 400 MHz and 100 MHz respectively.

[0046] Example 1

[0047] Weigh 3.52 g (40 mmol) of butyric acid, 0.46 g (5 mmol) of glycerol, and 0.20 g (5%, w / w) of 1-sulfobutyl-3-methylimidazolium chloride successively, and add them to a reflux reaction device equipped with stirring and oil bath temperature control. Start stirring and adjust the temperature to 130 °C, and react for 2 h. The specific reaction formula is as shown in Figure 1 A. The conversion rate of tributyrin can reach 94.6% by liquid chromatography analysis. After the reaction is completed, add distilled water and ethyl acetate to the reaction solution, extract thoroughly, collect the ethyl acetate layer, and remove the solvent by rotary evaporation to obtain 1.25 g of tributyrin with a purity of 99.1%. The pure product is used for structural characterization analysis, and the specific results are as follows.

[0048] HPLC( Figure 1 B): The retention time of glycerol in the chromatogram is 2.7 min, the response signal of butyric acid is weak, and its retention time is 3.1 min; in addition to the chromatographic peaks at 2.7 min and 3.1 min in the reaction solution, an obvious chromatographic peak appears at 6.1 min; the pure product at 6.1 min is obtained after extraction and separation.

[0049] FT-IR( Figure 1 C): Butyric acid has a broad peak between 2500 and 3500 cm -1 for the stretching vibration of the hydroxyl group of the free carboxyl group, and 1703 cm -1 is the carbonyl signal of the carboxyl group. For glycerol, 3277 cm -1 is the stretching vibration absorption of the free hydroxyl group, and 1031 cm -1 is the signal of the carbon-oxygen single bond. In the new product, there is no signal of the free carboxyl group of butyric acid molecules, and the absorption signal of the carbonyl group changes from 1703 cm -1 to 1736 cm -1 . In addition, the signal of the free hydroxyl group of glycerol molecules in the product disappears, and stretching vibration signals of the carbon-oxygen single bond appear at 1163 cm -1 and 1090 cm -1 . It can be seen from the above that there is an ester bond in the new product, indicating the formation of tributyrin. <s

[0050] MS( Figure 1 D): The molecular weight of butyric acid is 88, the molecular weight of glycerol is 92, and the molecular weight of the target compound tributyrin is 302. In the ES+ mass spectrum, m / z 325 is the [M+Na] + molecular ion peak of tributyrin.

[0051] NMR: The 1 H and 13 C NMR spectra of the new product are shown in Appendices Figure 1 E and 1F.

[0052] Example 2

[0053] 1.32 g (15 mmol) of butyric acid, 0.46 g (5 mmol) of glycerol, and 0.178 g (10%, w / w) of 1-sulfonic acid butyl-3-methylimidazolium hydrogen sulfate were weighed and added sequentially to a reflux reaction apparatus equipped with stirring and oil bath temperature control. Stirring was activated, the temperature was adjusted to 150°C, and the reaction was allowed to proceed for 0.5 h. Liquid chromatography analysis revealed a 92.3% conversion rate of tributyrin. Upon completion of the reaction, distilled water and ethyl acetate were added to the reaction solution for thorough extraction. The ethyl acetate layer was collected and the solvent removed by rotary evaporation to yield 1.11 g of tributyrin with a purity of 98.9%.

[0054] Example 3

[0055] 35.2 g (400 mmol) of butyric acid, 0.46 g (5 mmol) of glycerol, and 0.036 g (0.1%, w / w) of 1-sulfonic acid butyl-3-methylimidazolium trifluoromethanesulfonate were weighed and added sequentially to a reflux reaction apparatus equipped with stirring and oil bath temperature control. Stirring was activated, the temperature was adjusted to 90°C, and the reaction was allowed to proceed for 6 hours. Liquid chromatography analysis revealed a 93.6% conversion rate of tributyrin. After the reaction was completed, distilled water and ethyl acetate were added to the reaction solution for thorough extraction. The ethyl acetate layer was collected and the solvent removed by rotary evaporation to yield 1.22 g of tributyrin with a purity of 99.4%.

[0056] Example 4

[0057] 8.8 g (100 mmol) of butyric acid, 0.46 g (5 mmol) of glycerol, and 0.093 g (1%, w / w) of Amberlyst 15 were weighed and added sequentially to a reflux reactor equipped with stirring and oil bath temperature control. Stirring was activated, the temperature was adjusted to 80°C, and the reaction was allowed to proceed for 12 hours. Liquid chromatography analysis revealed a 91.2% conversion rate of tributyrin. After the reaction was complete, distilled water and ethyl acetate were added to the reaction solution for thorough extraction. The ethyl acetate layer was collected and the solvent removed by rotary evaporation to yield 1.13 g of tributyrin with a purity of 97.6%.

[0058] Comparative Example 1

[0059] Weigh 3.52 g (40 mmol) of butyric acid, 0.46 g (5 mmol) of glycerol, and 0.20 g (5%, w / w) of catalyst (1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium hydrogensulfate, or 1-butyl-3-methylimidazolium trifluoromethanesulfonate) respectively, and add them successively to a reflux reaction device equipped with stirring and oil bath temperature control. Start stirring and adjust the temperature to 130 °C, and react for 12 h. The conversion rates of glyceryl tributyrate in the reaction solutions using the three ionic liquids as catalysts are 15.3%, 20.5%, and 25.7% respectively as analyzed by liquid chromatography. After the reaction is completed, add distilled water and ethyl acetate to the reaction solution, extract thoroughly, collect the ethyl acetate layer, and remove the solvent by rotary evaporation to obtain 0.18 g, 0.22 g, and 0.27 g of glyceryl tributyrate respectively, with purities of 94.6%, 95.2%, and 94.9% respectively. The ionic liquids used in Comparative Example 1: 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium hydrogensulfate, or 1-butyl-3-methylimidazolium trifluoromethanesulfonate, all have no sulfonic acid group. The reaction time is 12 h, which is long, and the amount of glyceryl tributyrate obtained is very small. While the catalyst used in Example 1 is a sulfonic acid group ionic liquid: 1-sulfobutyl-3-methylimidazolium chloride. After reacting for 2 h, 1.25 g of glyceryl tributyrate is obtained. It can be seen that using a sulfonic acid group ionic liquid as a catalyst takes a short time and is beneficial to promoting the formation of glyceryl tributyrate.

[0060] Example 5

[0061] Weigh 4.44 g (60 mmol) of propionic acid, 0.55 g (6 mmol) of glycerol, and 0.23 g (5%, w / w) of 1-sulfobutyl-3-methylimidazolium chloride respectively, and add them successively to a reflux reaction device equipped with stirring and oil bath temperature control. Start stirring and adjust the temperature to 115 °C, and react for 4 h. The specific reaction formula is as Figure 2 shown in A. The conversion rate of glyceryl tripropionate can reach 92.2% as analyzed by liquid chromatography. After the reaction is completed, add distilled water and ethyl acetate to the reaction solution, extract thoroughly, collect the ethyl acetate layer, and remove the solvent by rotary evaporation to obtain 1.29 g of glyceryl tripropionate with a purity of 98.8%. The pure product is used for structural characterization analysis, and the specific results are as follows.

[0062] HPLC( Figure 2 B): The retention time of glycerol in the chromatogram is 2.7 min, the response signal of propionic acid is weak, and its retention time is 3.0 min; in addition to the chromatographic peaks at 2.7 min and 3.0 min in the reaction solution, an obvious chromatographic peak appears at 4.1 min; the pure product at 4.1 min is obtained after extraction and separation.

[0063] FT-IR( Figure 2 C): For propionic acid, in the range of 2300 - 3500 cm -1There is a broad peak between them, which is the stretching vibration of the hydroxyl group of the free carboxyl group, 1708 cm -1 It is the carbonyl signal of carboxyl group. 3277cm in glycerol -1 The stretching vibration absorption of free hydroxyl groups is 1031 cm -1 The new product does not contain the free carboxyl group signal of the propionic acid molecule, and the absorption signal of the carbonyl group changes from 1703cm -1 becomes 1736cm -1 In addition, the signal of the free hydroxyl group of glycerol molecules in the product disappeared, and the signal at 1163 cm -1 and 1090cm -1 The stretching vibration signals of carbon-oxygen single bonds appeared at all sites. From the above, we can see that there is an ester bond in the new product, indicating that tripropionin is generated.

[0064] MS( Figure 2 D): The molecular weight of propionic acid is 74, the molecular weight of glycerol is 92, and the molecular weight of the target compound tripropionin is 260. In the ES+ mass spectrum, m / z 283 is the [M+Na] of tripropionin. + Molecular ion peak.

[0065] NMR: New product 1 H and 13 C NMR spectrum is attached Figure 2 E and 2F.

[0066] The comprehensive results of HPLC, FT-IR, MS and NMR showed that the new product was the target molecule tripropionin.

[0067] Example 6

[0068] 44.4 g (600 mmol) of propionic acid, 0.55 g (6 mmol) of glycerol, and 0.045 g (0.1%, w / w) of HND-580 were weighed and added sequentially to a reflux reactor equipped with stirring and oil bath temperature control. Stirring was activated, the temperature was adjusted to 140°C, and the reaction was continued for 6 hours. Liquid chromatography analysis showed a conversion rate of 93.8% for tripropionin. After the reaction was completed, distilled water and ethyl acetate were added to the reaction solution for thorough extraction. The ethyl acetate layer was collected and the solvent removed by rotary evaporation to yield 1.34 g of tripropionin with a purity of 98.9%.

[0069] Example 7

[0070] 13.32 g (180 mmol) of propionic acid, 0.55 g (6 mmol) of glycerol, and 0.69 g (5%, w / w) of 1-sulfonic acid butyl-3-methylimidazolium trifluoromethanesulfonate were weighed and added sequentially to a reflux reaction apparatus equipped with stirring and oil bath temperature control. Stirring was started, the temperature was adjusted to 80°C, and the reaction was allowed to proceed for 12 hours. Liquid chromatography analysis showed a conversion rate of 94.7% for tripropionin. After the reaction was completed, distilled water and ethyl acetate were added to the reaction solution for thorough extraction. The ethyl acetate layer was collected and the solvent removed by rotary evaporation to yield 1.32 g of tripropionin with a purity of 99.1%.

[0071] Example 8

[0072] 1.33 g (18 mmol) of propionic acid, 0.55 g (6 mmol) of glycerol, and 0.18 g (10%, w / w) of 1-sulfonic acid butyl-3-methylimidazolium trifluoromethanesulfonate were weighed and added sequentially to a reflux reaction apparatus equipped with stirring and oil bath temperature control. Stirring was started, the temperature was adjusted to 140°C, and the reaction was allowed to proceed for 4 hours. Liquid chromatography analysis showed a conversion rate of 93.2% for tripropionin. After the reaction was completed, distilled water and ethyl acetate were added to the reaction solution for thorough extraction. The ethyl acetate layer was collected and the solvent removed by rotary evaporation to yield 1.2 g of tripropionin with a purity of 99.2%.

[0073] Comparative Example 2

[0074] 4.44 g (60 mmol) of propionic acid, 0.55 g (6 mmol) of glycerol, and 0.23 g (5%, w / w) of a catalyst (1-butyl-3-methylimidazole hydrochloride, 1-butyl-3-methylimidazole hydrogen sulfate, or 1-butyl-3-methylimidazole trifluoromethanesulfonate) were weighed and added sequentially to a reflux reactor equipped with stirring and oil bath temperature control. Stirring was initiated, the temperature was adjusted to 115°C, and the reaction was allowed to proceed for 12 hours. Liquid chromatography analysis of the reaction solutions using the three ionic liquids as catalysts revealed 18.3%, 25.1%, and 29.7% conversions of tripropionin, respectively. After the reaction was complete, distilled water and ethyl acetate were added to the reaction solutions for thorough extraction. The ethyl acetate layer was collected and the solvent removed by rotary evaporation to yield 0.18 g, 0.29 g, and 0.36 g of tripropionin, respectively, with purities of 95.3%, 95.7%, and 94.8%, respectively. The ionic liquids used in Comparative Example 2, 1-butyl-3-methylimidazole hydrochloride, 1-butyl-3-methylimidazole hydrogen sulfate, or 1-butyl-3-methylimidazole trifluoromethanesulfonate, all lack sulfonic acid groups. The reaction took 12 hours, which is long, and the amount of tripropionin produced was very small. In contrast, the catalyst used in Example 5 was a sulfonic acid ionic liquid, 1-sulfonic acid butyl-3-methylimidazole hydrochloride. After a 4-hour reaction, 1.29 g of tripropionin was obtained. This demonstrates that using a sulfonic acid ionic liquid as a catalyst shortens the reaction time and facilitates the formation of tripropionin.

[0075] Example 9

[0076] Experimental animals and grouping. Thirty-six 8-week-old male C57BL / 6J mice were provided by the Experimental Animal Center of Jiangsu University. Before the experiment, the mice were adaptively fed for one week and then randomly divided into 6 groups (n = 6 in each group): control group (CTL), model group (DSS), low-dose tributyrin group (LTb), high-dose tributyrin group (HTb), low-dose tripropionate group (LTp), and high-dose tripropionate group (HTp).

[0077] Feed formulation and treatment. The CTL group and the DSS group were fed the same basal diet, and the four sample groups were fed basal diets supplemented with 0.5% tributyrin, 1% tributyrin, 0.5% tripropionate, and 1% tripropionate, respectively. The specific formulations are shown in Table 1. All feeds were prepared by Jiangsu Xietong Pharmaceutical Biotechnology Co., Ltd. and sterilized by 60 Co-γ ray irradiation.

[0078] Table 1 Nutritional composition of feeds for each group

[0079]

[0080]

[0081] Experimental design and operation. 1) Adaptation stage (1 week): All mice were adapted for one week before the experiment, fed the basal diet, and given ordinary water to drink. 2) Pre-intervention stage (1 week): The CTL group and the DSS group were fed the basal diet and given ordinary water to drink. The four sample groups LTb, HTb, LTp, and HTp were fed basal diets containing 0.5% and 1.0% tributyrin and tripropionate, respectively, and given ordinary water to drink. 3) DSS modeling stage (1 week): A dextran sulfate sodium (DSS, relative molecular weight 40,000 Da) -induced colitis model was used. The specific protocol was as follows: CTL group: basal diet, ordinary drinking water. DSS group: basal diet, 2.5% (w / w) DSS drinking water. LTb, HTb, LTp, and HTp groups: basal diets containing 0.5% and 1.0% tributyrin and tripropionate, 2.5% (w / w) DSS drinking water. During the modeling period, the body weight of the mice was recorded at a fixed time every day, and the fecal status was observed. 4) Sample collection: After the modeling was completed, the mice were anesthetized with isoflurane and then sacrificed by cervical dislocation. The colon was dissected, the colon length was measured, and photos were taken. Colonic tissue about 0.7 cm from the anus was taken and fixed in 4% paraformaldehyde solution for histological section analysis.

[0082] Figure 3A is the change in body weight of mice in each group. As the number of days of modeling increased, the body weight of mice in the CTL group remained basically unchanged, while that of mice in the DSS group decreased significantly. In particular, from the 4th day to the 7th day, the body weight of the DSS group showed a linear downward trend; in contrast, the downward trend of body weight in the four intervention groups of LTb, HTb, LTp, and HTp was relatively mild, and there were significant differences between HTb and HTp and the DSS group (p<0.05). Figure 3 B is the score of the Disease Activity Index (DAI) of mice in each group. The DAI score of the CTL group was the lowest, while that of the DSS group was the highest. In contrast, the DAI scores of LTb, HTb, LTp, and HTp were significantly lower than those of the DSS group. It indicates that tributyrin and tripalmitin can effectively prevent colitis.

[0083] Figure 3 C and 3D are the typical colon appearance and the statistical results of colon length of mice in each group respectively. As can be seen from the figure, the colon length of mice in the DSS group was significantly shorter than that in the CTL group (p<0.01), while the LTb, HTb, LTp, and HTp intervention groups inhibited colon shortening, and this effect became more obvious with the increase in dose. There were statistical differences between the HTb and HTp groups and the DSS group (p<0.05). Figure 3 E and 3F are the pathological sections of colon tissues of each group and the statistical results. As can be seen from the figure, tributyrin and tripalmitin can significantly reduce the infiltration of inflammatory cells, mucosal damage, and histological scores in colon tissues. In summary, tributyrin and tripalmitin can effectively prevent colitis.

[0084] It should be understood that although this specification is described according to each embodiment, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0085] The series of detailed descriptions listed above are only specific descriptions of the feasible embodiments of the present invention, and they are not intended to limit the protection scope of the present invention. Any equivalent embodiments or changes made without departing from the technical spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a short-chain fatty acid ester, characterized in that, It includes the following steps: Step S1: Mix short-chain fatty acids, glycerol and a catalyst and react under heating and stirring; Step S2: After the reaction ends, take out the reaction solution, remove the catalyst, and obtain a crude product of short-chain fatty acid ester; Step S3: Obtain a pure product of short-chain fatty acid ester through separation.

2. The preparation method of the short-chain fatty acid ester according to claim 1, wherein In step S1, the short-chain fatty acid is butyric acid or propionic acid.

3. The method for preparing short-chain fatty acid esters according to claim 1, wherein, In step S1, the catalyst is an acidic ionic liquid or a solid acid.

4. The preparation method of the short-chain fatty acid ester according to claim 3, characterized in that, The acidic ionic liquid is one of 1-sulfobutyl-3-methylimidazolium chloride, 1-sulfobutyl-3-methylimidazolium hydrogen sulfate, and 1-sulfobutyl-3-methylimidazolium trifluoromethanesulfonate.

5. The preparation method of the short-chain fatty acid ester according to claim 3, wherein The solid acid is Amberlyst15 or HND-580.

6. The preparation method of the short-chain fatty acid ester according to claim 1, characterized in that, In step S1, the molar ratio of glycerol to short-chain fatty acid is 1:3 to 1:100; the catalyst addition amount is 0.1% to 10% of the sum of the substrate masses; the reaction temperature is 80°C to 150°C, and the reaction time is 0.5 h to 12 h.

7. The preparation method of the short-chain fatty acid ester according to claim 6, characterized in that, The molar ratio of glycerol to short-chain fatty acid is 1:3 to 1:30; the catalyst addition amount is 0.5% to 5% of the sum of the substrate masses; the reaction temperature is 90°C to 140°C, and the reaction time is 1 h to 10 h.

8. The preparation method of the short-chain fatty acid ester according to claim 1, wherein The short-chain fatty acid ester is tributyrin or tripropionin.

9. A short-chain fatty acid ester, characterized in that, Prepared according to the preparation method of the short-chain fatty acid ester described in any one of claims 1 to 8.

10. Use of a short-chain fatty acid ester, characterized in that, Use of the short-chain fatty acid ester described in claim 9 in the preparation of foods, medicines or feeds for relieving colitis.

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