A method for synthesizing an amadori compound

Abstract

The application discloses a synthesis method of Amadori compound and belongs to the field of organic synthesis. The application uses lactic acid, glycerol and choline chloride to prepare a low eutectic solvent, which is used as a reaction system of the Amadori compound. The low eutectic solvent system has excellent solubility for reducing sugar and amino acid, does not need a cosolvent, has a uniform reaction system and high mass transfer efficiency. The components (choline chloride, glycerol and lactic acid) used are all natural biodegradable substances, and are non-toxic and non-residual. The subsequent NADES can be recovered by ethanol precipitation, and the recycling rate is more than 95%, and basically no three wastes are discharged.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis, specifically relating to a method for synthesizing Amadori compounds. Background Technology

[0002] Other names for Amadori compounds include amino acid glycosides, ACS, and ARP. Essentially, they are formed by the nucleophilic addition reaction between the carbonyl group of a sugar and the amino group of an amino acid to form a glycosylamine Schiff base, which is then rearranged by Amadori or Heyns rearrangement to form a relatively stable Maillard reaction intermediate, N-(l-deoxy-D-fructopyranos-l-y1)-amino acid (Amadori).

[0003] Currently, Amadori compounds are mainly synthesized in aqueous or organic solvent systems, but these systems have many drawbacks, such as: 1. Reaction selectivity: pH is difficult to control in aqueous systems, which can easily lead to browning and cracking in the Maillard reaction, resulting in a yield of only 1%-2% for Amadori compounds; organic solvent systems have poor solubility for polar substrates, produce many byproducts, and have low product purity.

[0004] 2. Reaction conditions: The aqueous phase requires high temperature (110-180℃), which consumes a lot of energy and easily produces harmful substances such as acrylamide; the organic solvent is volatile and requires high pressure or closed equipment.

[0005] 3. Substrate solubility: Water has low solubility for hydrophobic amino acids, requiring the addition of a solubilizing agent; organic solvents have poor solubility for highly polar substrates such as sugars.

[0006] 4. Environmental friendliness: Organic solvents are toxic and volatile, and can easily cause environmental pollution.

[0007] 5. Economic costs: Organic solvents are expensive and difficult to recover, high-temperature reactions consume a lot of energy, and subsequent separation and purification steps are complicated.

[0008] Therefore, it is necessary to improve the reaction system for Amadori compounds in order to increase the yield of Amadori synthesis and reduce the synthetic difficulty of the reaction. Summary of the Invention

[0009] Technical issues Existing Amadori compounds are mainly synthesized in aqueous or organic solvent systems, which presents many technical problems: the pH of the aqueous phase is difficult to control, resulting in extremely low product yields; high temperatures are required, and harmful substances are easily generated; and the solubility of hydrophobic amino acids is poor. Organic solvents have poor solubility for polar substrates, produce many byproducts, and are volatile, toxic, and pollute the environment. At the same time, they are expensive and difficult to recover. In addition, the subsequent separation and purification of the two systems are cumbersome, resulting in high overall economic costs. Therefore, there is an urgent need to improve the reaction system.

[0010] Technical content To address the aforementioned issues, this invention provides a choline chloride-lactic acid-glycerol eutectic solvent (NADES) as the reaction system for Amadori compounds. Lactic acid provides a weakly acidic environment (pH 3-4), precisely suppressing subsequent side reactions, and the strong hydrogen bond network stabilizes the sugar ring-opening structure, resulting in highly selective generation of the target product.

[0011] This eutectic solvent system exhibits excellent solubility for reducing sugars and amino acids (including hydrophobic amino acids), requires no co-solvent, produces a homogeneous reaction system, and has high mass transfer efficiency. The components used (choline chloride, glycerol, and lactic acid) are all natural, biodegradable substances, non-toxic, and residue-free. NADES can be recovered via ethanol precipitation, achieving a recycling rate of over 95% and virtually eliminating waste emissions.

[0012] In addition, the present invention also provides a synthesis method based on the above-mentioned NADES system, in which energy consumption can be reduced by more than 50% by using a mild reaction temperature (40-80℃), and no harmful substances are generated or there is any risk of volatilization. It can be operated at atmospheric pressure and has low equipment requirements.

[0013] The present invention provides a eutectic solvent for preparing Amadori compounds, the eutectic solvent being composed of choline chloride, lactic acid and glycerol.

[0014] Furthermore, the molar ratio of choline chloride, lactic acid, and glycerol in the eutectic solvent is 1~2:1~6:1~3.

[0015] Furthermore, the molar ratio of choline chloride to lactic acid in the eutectic solvent is 1:0.1~6.

[0016] Preferably, the molar ratio of choline chloride to lactic acid in the eutectic solvent is 1:0.5~5.

[0017] More preferably, the molar ratio of choline chloride to lactic acid in the eutectic solvent is 1:0.5~4.

[0018] Furthermore, the molar ratio of choline chloride to glycerol in the eutectic solvent is 1:0.1~5.

[0019] Preferably, the molar ratio of choline chloride to lactic acid in the eutectic solvent is 1:0.5~4.

[0020] More preferably, the molar ratio of choline chloride to glycerol in the eutectic solvent is 1:0.5~3.

[0021] Specifically, the molar ratio of choline chloride, lactic acid and glycerol can be selected from any of the following ratios: 1:1:1, 1:1:2, 1:1:3, 1:2:1, 1:3:1, 1:4:1, 2:1:1, 2:6:3.

[0022] The present invention also provides a method for preparing the above-mentioned eutectic solvent, wherein the preparation method comprises: Take choline chloride, lactic acid and glycerol, mix them and then heat and stir until the system becomes a transparent, non-layered viscous liquid, which is the eutectic solvent of choline chloride, lactic acid and glycerol.

[0023] Furthermore, the heating temperature is 70~90℃, and the heating time is 1~5 hours.

[0024] The present invention also provides a method for preparing Amadori compounds based on the above-mentioned eutectic solvent, the preparation method comprising the following steps: (1) Synthesis of Amadori compounds: Take the above eutectic solvent, add sugar and amino acids and then heat to react; (2) Product separation and purification: After the reaction is complete, methanol is added for dilution, and then ethanol is added for precipitation. After filtration, the precipitate is collected to obtain the Amadori compound.

[0025] Furthermore, the sugar in step (1) includes glucose and xylose.

[0026] Furthermore, the acids in step (1) include arginine, phenylalanine, leucine, methionine, and valine.

[0027] Furthermore, in step (1), the molar ratio of sugar to acid is 1:0.1~10.

[0028] Furthermore, in step (1), the molar ratio of sugar to acid is 1:0.5~5.

[0029] Furthermore, in step (1), the total concentration of sugar and acid in the eutectic solvent is 0.1~0.5 mol / L.

[0030] Furthermore, in step (1), the heating reaction temperature is 70~90℃ and the time is 1~3 hours.

[0031] Furthermore, in step (1), methanol can replace ethanol.

[0032] Furthermore, in step (1), ethanol can be replaced with acetone.

[0033] Beneficial effects This invention synthesizes Amadori compounds using a choline chloride-lactic acid-glycerol eutectic solvent as the reaction system, achieving high-yield preparation and convenient separation of the target product, while also possessing advantages such as being environmentally friendly and having mild reaction conditions. Compared with existing technologies, the specific beneficial effects are as follows: 1. Significantly improved yield: Compared with the extremely low yield of 1%-2% in traditional aqueous systems, the crude yield of Amadori compounds can reach up to 95.73% in the optimized eutectic solvent system of this invention. Different ratio systems can achieve yield performance far superior to traditional methods, effectively solving the core problem of low yield in traditional synthesis processes.

[0034] 2. Easy product separation and purification: After the reaction, only three steps are required to obtain the target product: dilution with methanol, precipitation with ethanol (or acetone) and filtration. The separation steps are simple and efficient. Moreover, the eutectic solvent system can avoid problems such as the product being viscous, difficult to precipitate, and difficult to filter, which greatly reduces the separation difficulty and improves the preparation efficiency.

[0035] 3. Excellent solvent and system compatibility: This eutectic solvent has good solubility for reducing sugars and various amino acids (including hydrophobic amino acids), eliminating the need for co-solvents. The reaction system is homogeneous and has high mass transfer efficiency, ensuring the reaction proceeds fully and further contributing to increased yield.

[0036] 4. Green, environmentally friendly, economical and efficient: The solvent component is a natural biodegradable substance, which is non-toxic and leaves no residue. It can be recovered through ethanol precipitation, with a recycling rate of over 95% and virtually no emissions of waste. The reaction is carried out at normal pressure under mild conditions of 70~90℃, reducing energy consumption by more than 50%. It does not require high-pressure sealed devices, has low equipment requirements, and significantly saves preparation costs.

[0037] 5. High reaction selectivity: Lactic acid provides a weakly acidic environment of pH 3-4, which, combined with the strong hydrogen bond network of the system, can precisely suppress subsequent side reactions such as browning and cleavage in the Maillard reaction, stabilize the ring-opening structure of sugar, and generate Amadori compounds with high selectivity, ensuring product purity. Attached Figure Description

[0038] Figure 1 This is a mass spectrum fragmentation diagram of N-(1-deoxy-1-fructosyl)valine.

[0039] Figure 2 This is a product image from Example 2.

[0040] Figure 3 The images show the eutectic solvent, reaction process, and reaction products in Example 1.

[0041] Figure 4 The images show the eutectic solvent, reaction process, and reaction products in Example 2.

[0042] Figure 5 The images show the eutectic solvent, reaction process, and reaction products in Example 3.

[0043] Figure 6 The images show the eutectic solvent, reaction process, and reaction products in Example 4.

[0044] Figure 7 The images show the eutectic solvent, reaction process, and reaction products in Example 5.

[0045] Figure 8 The images show the eutectic solvent, reaction process, and reaction products in Example 6.

[0046] Figure 9 The images show the eutectic solvent, reaction process, and reaction products in Example 7.

[0047] Figure 10 The images show the eutectic solvent, reaction process, and reaction products in Example 8.

[0048] Figure 11 The images show the eutectic solvent, reaction process, and reaction products in Comparative Example 1.

[0049] Figure 12 The images show the eutectic solvent, reaction process, and reaction products in Comparative Example 2.

[0050] Figure 13 The images show the eutectic solvent, reaction process, and reaction products in Comparative Example 3.

[0051] Figure 14 The images show the eutectic solvent, reaction process, and reaction products in Comparative Example 4.

[0052] Figure 15 The images show the eutectic solvent, reaction process, and reaction products in Comparative Example 5.

[0053] Figure 16 These are TLC images taken during the reaction process in Example 2.

[0054] Figure 17 The image shows the IR spectrum of N-(1-deoxy-1-fructosyl)valine obtained in Example 2.

[0055] Figure 18 TIC chromatography of N-(1-deoxy-1-fructosyl)valine obtained in Example 2.

[0056] Figure 19The liquid chromatography-mass spectra of N-(1-deoxy-1-fructosyl)valine obtained in Example 2 are shown.

[0057] Figure 20 The DPPH and ABTS free radical scavenging rates of N-(1-deoxy-1-fructosyl)valine obtained in Example 2 are given.

[0058] Figure 21 This is the liquid chromatography-mass spectra of Example 9.

[0059] Figure 22 This is the liquid chromatography-mass spectra of Example 10.

[0060] Figure 23 This is the liquid chromatography-mass spectra of Example 11.

[0061] Figure 24 This is the liquid chromatography-mass spectra of Example 12.

[0062] Figure 25 This is the liquid chromatography-mass spectra of Example 13.

[0063] Figure 26 This is the liquid chromatography-mass spectra of Example 14. Detailed Implementation

[0064] Example 1 Weigh out 60g of choline chloride, lactic acid, and glycerol in a 1:1:1 molar ratio. Add the three raw materials to a three-necked flask or sealed glass container equipped with a magnetic stirrer. Heat in an oil bath at 80℃ with a stirring speed of 1000 rpm for 2 hours until the system becomes a dark brown, transparent, non-layered viscous liquid, thus obtaining the choline chloride-lactic acid-glycerol eutectic solvent (NADES). If trace amounts of water or air bubbles need to be removed from the system, it can be treated in a vacuum drying oven at 45℃ and -0.1 MPa for 2 hours. Then, take 60mL of the prepared NADES and add glucose and arginine in a 1:1 molar ratio. The total concentration of the substrate (glucose and arginine) should be controlled at 0.16mol / L. Reaction conditions: constant temperature stirring at 80℃ for 2 hours to avoid side reactions caused by high temperature. After the reaction is complete, dilute with methanol, then precipitate with ethanol. After filtration, the Amadori compound is obtained. The crude yield is 95.73%.

[0065] Example 2 Weigh out 60g of choline chloride, lactic acid, and glycerol in a 1:1:2 molar ratio. Add the three raw materials to a three-necked flask or sealed glass container equipped with a magnetic stirrer. Heat in an oil bath at 80℃ with a stirring speed of 1000 rpm for 2 hours until the system becomes a dark brown, transparent, non-layered viscous liquid, thus obtaining the choline chloride-lactic acid-glycerol eutectic solvent (NADES). If trace amounts of water or air bubbles need to be removed from the system, it can be treated in a vacuum drying oven at 45℃ and -0.1 MPa for 2 hours. Then, take 60mL of the prepared NADES and add glucose and arginine in a 1:1 molar ratio. The total concentration of the substrate (glucose and arginine) should be controlled at 0.16mol / L. Reaction conditions: constant temperature stirring at 80℃ for 2 hours to avoid side reactions caused by high temperature. After the reaction is complete, dilute with methanol, then precipitate with ethanol. After filtration, the Amadori compound is obtained. The crude yield is 84.33%.

[0066] Example 3 Weigh out 60g of choline chloride, lactic acid, and glycerol in a 1:1:3 molar ratio. Add the three raw materials to a three-necked flask or sealed glass container equipped with a magnetic stirrer. Heat in an oil bath at 80℃ with a stirring speed of 1000 rpm for 2 hours until the system becomes a dark brown, transparent, non-layered viscous liquid, thus obtaining the choline chloride-lactic acid-glycerol eutectic solvent (NADES). If trace amounts of water or air bubbles need to be removed from the system, it can be treated in a vacuum drying oven at 45℃ and -0.1 MPa for 2 hours. Then, take 60mL of the prepared NADES and add glucose and arginine in a 1:1 molar ratio. The total concentration of the substrate (glucose and arginine) should be controlled at 0.16mol / L. Reaction conditions: constant temperature stirring at 80℃ for 2 hours to avoid side reactions caused by high temperature. After the reaction is complete, dilute with methanol, then precipitate with ethanol. After filtration, the Amadori compound is obtained. The crude yield is 52.28%.

[0067] Example 4 Weigh out 60g of choline chloride, lactic acid, and glycerol in a 1:2:1 molar ratio. Add the three raw materials to a three-necked flask or sealed glass container equipped with a magnetic stirrer. Heat in an oil bath at 80℃ with a stirring rate of 1000 rpm for 2 hours until the system becomes a dark brown, transparent, non-layered viscous liquid, thus obtaining the choline chloride-lactic acid-glycerol eutectic solvent (NADES). If trace amounts of water or air bubbles need to be removed from the system, it can be treated in a vacuum drying oven at 45℃ and -0.1 MPa for 2 hours. Then, take 60mL of the prepared NADES and add glucose and arginine in a 1:1 molar ratio. The total concentration of the substrate (glucose and arginine) should be controlled at 0.16mol / L. Reaction conditions: constant temperature stirring at 80℃ for 2 hours to avoid side reactions caused by high temperature. After the reaction is complete, dilute with methanol, then precipitate with ethanol. After filtration, the Amadori compound is obtained. The crude yield is 57.8%.

[0068] Example 5 Weigh out 60g of choline chloride, lactic acid, and glycerol in a 1:3:1 molar ratio. Add the three raw materials to a three-necked flask or sealed glass container equipped with a magnetic stirrer. Heat in an oil bath at 80℃ with a stirring speed of 1000 rpm for 2 hours until the system becomes a dark brown, transparent, non-layered viscous liquid, thus obtaining the choline chloride-lactic acid-glycerol eutectic solvent (NADES). If trace amounts of water or air bubbles need to be removed from the system, it can be treated in a vacuum drying oven at 45℃ and -0.1 MPa for 2 hours. Then, take 60mL of the prepared NADES and add glucose and arginine in a 1:1 molar ratio. The total concentration of the substrate (glucose and arginine) should be controlled at 0.16mol / L. Reaction conditions: constant temperature stirring at 80℃ for 2 hours to avoid side reactions caused by high temperature. After the reaction is complete, dilute with methanol, then precipitate with ethanol. After filtration, the Amadori compound is obtained. The crude yield is 88.29%.

[0069] Example 6 Weigh out 60g of choline chloride, lactic acid, and glycerol in a 1:4:1 molar ratio. Add the three raw materials to a three-necked flask or sealed glass container equipped with a magnetic stirrer. Heat in an oil bath at 80℃ with a stirring rate of 1000 rpm for 2 hours until the system becomes a dark brown, transparent, non-layered viscous liquid, thus obtaining the choline chloride-lactic acid-glycerol eutectic solvent (NADES). If trace amounts of water or air bubbles need to be removed from the system, it can be treated in a vacuum drying oven at 45℃ and -0.1 MPa for 2 hours. Then, take 60mL of the prepared NADES and add glucose and arginine in a 1:1 molar ratio. The total concentration of the substrate (glucose and arginine) should be controlled at 0.16mol / L. Reaction conditions: constant temperature stirring at 80℃ for 2 hours to avoid side reactions caused by high temperature. After the reaction is complete, dilute with methanol, then precipitate with ethanol. After filtration, the Amadori compound is obtained. The crude yield is 78.87%.

[0070] Example 7 Weigh out 60g of choline chloride, lactic acid, and glycerol in a 2:1:1 molar ratio. Add the three raw materials to a three-necked flask or sealed glass container equipped with a magnetic stirrer. Heat in an oil bath at 80℃ with a stirring speed of 1000 rpm for 2 hours until the system becomes a dark brown, transparent, non-layered viscous liquid, thus obtaining the choline chloride-lactic acid-glycerol eutectic solvent (NADES). If trace amounts of water or air bubbles need to be removed from the system, it can be treated in a vacuum drying oven at 45℃ and -0.1 MPa for 2 hours. Then, take 60mL of the prepared NADES and add glucose and arginine in a 1:1 molar ratio. The total concentration of the substrate (glucose and arginine) should be controlled at 0.16mol / L. Reaction conditions: constant temperature stirring at 80℃ for 2 hours to avoid side reactions caused by high temperature. After the reaction is complete, dilute with methanol, then precipitate with ethanol. After filtration, the Amadori compound is obtained. The crude yield is 73.61%.

[0071] Example 8 Weigh out 60g of choline chloride, lactic acid, and glycerol in a 2:6:3 molar ratio. Add the three raw materials to a three-necked flask or sealed glass container equipped with a magnetic stirrer. Heat in an oil bath at 80℃ with a stirring speed of 1000 rpm for 2 hours until the system becomes a dark brown, transparent, non-layered viscous liquid, thus obtaining the choline chloride-lactic acid-glycerol eutectic solvent (NADES). If trace amounts of water or air bubbles need to be removed from the system, it can be treated in a vacuum drying oven at 45℃ and -0.1 MPa for 2 hours. Then, take 60mL of the prepared NADES and add glucose and arginine in a 1:1 molar ratio. The total concentration of substrate (glucose and arginine) should be controlled at 0.16mol / L. Reaction conditions: constant temperature stirring at 80℃ for 2 hours to avoid side reactions caused by high temperature. After the reaction is complete, dilute with methanol, then precipitate with ethanol. After filtration, the Amadori compound is obtained. The crude yield is 67.36%.

[0072] Example 9 Similar to Example 5, 60g of choline chloride, lactic acid, and glycerol were weighed in a 1:3:1 molar ratio and added to a three-necked flask or sealed glass container equipped with a magnetic stirrer. The container was heated in an oil bath at 80°C with a stirring rate of 1000 rpm for 2 hours until the system became a dark brown, transparent, non-layered viscous liquid, thus obtaining the choline chloride-lactic acid-glycerol eutectic solvent (NADES). If trace amounts of water or air bubbles need to be removed, the system can be treated in a vacuum drying oven at 45°C and -0.1 MPa for 2 hours. The difference lies in that 60mL of the prepared NADES was added to glucose and phenylalanine in a 1:1 molar ratio, and the total concentration of the substrate (glucose and phenylalanine) was controlled at 0.16 mol / L. Reaction conditions: constant temperature stirring at 80°C for 2 hours to avoid side reactions caused by high temperature. After the reaction, 1mL of the reaction solution was diluted 10 times for LC-MS detection.

[0073] Example 10 Similar to Example 5, 60g of choline chloride, lactic acid, and glycerol were weighed in a 1:3:1 molar ratio and added to a three-necked flask or sealed glass container equipped with a magnetic stirrer. The container was heated in an oil bath at 80°C with a stirring rate of 1000 rpm for 2 hours until the system became a dark brown, transparent, non-layered viscous liquid, thus obtaining the choline chloride-lactic acid-glycerol eutectic solvent (NADES). If trace amounts of water or air bubbles need to be removed, the system can be treated in a vacuum drying oven at 45°C and -0.1 MPa for 2 hours. The difference lies in that 60mL of the prepared NADES was added to glucose and methionine in a 1:1 molar ratio, and the total concentration of the substrate (glucose and methionine) was controlled at 0.16 mol / L. Reaction conditions: constant temperature stirring at 80°C for 2 hours to avoid side reactions caused by high temperature. After the reaction, 1mL of the reaction solution was diluted 10 times for LC-MS detection.

[0074] Example 11 Similar to Example 5, 60g of choline chloride, lactic acid, and glycerol were weighed in a 1:3:1 molar ratio and added to a three-necked flask or sealed glass container equipped with a magnetic stirrer. The container was heated in an oil bath at 80°C with a stirring speed of 1000 rpm for 2 hours until the system became a dark brown, transparent, non-layered viscous liquid, thus obtaining the choline chloride-lactic acid-glycerol eutectic solvent (NADES). If trace amounts of water or air bubbles need to be removed, the system can be treated in a vacuum drying oven at 45°C and -0.1 MPa for 2 hours. The difference lies in that 60mL of the prepared NADES was added to glucose and tryptophan in a 1:1 molar ratio, and the total concentration of the substrate (glucose and tryptophan) was controlled at 0.16 mol / L. Reaction conditions: constant temperature stirring at 80°C for 2 hours to avoid side reactions caused by high temperature. After the reaction, 1mL of the reaction solution was diluted 10 times for LC-MS detection.

[0075] Example 12 Similar to Example 5, 60g of choline chloride, lactic acid, and glycerol were weighed and added to a three-necked flask or sealed glass container equipped with a magnetic stirrer. The container was heated in an oil bath at 80°C with a stirring rate of 1000 rpm for 2 hours until the system became a dark brown, transparent, non-layered viscous liquid, thus obtaining the choline chloride-lactic acid-glycerol eutectic solvent (NADES). If trace amounts of water or air bubbles need to be removed, the system can be treated in a vacuum drying oven at 45°C and -0.1 MPa for 2 hours. The difference lies in that 60mL of the prepared NADES was added to xylose and leucine at a molar ratio of 1:1, and the total concentration of the substrate (xylose and leucine) was controlled at 0.16mol / L. Reaction conditions: constant temperature stirring at 80°C for 2 hours to avoid side reactions caused by high temperature. After the reaction, 1mL of the reaction solution was diluted 10 times for LC-MS detection.

[0076] Example 13 Similar to Example 5, 60g of choline chloride, lactic acid, and glycerol were weighed and added to a three-necked flask or sealed glass container equipped with a magnetic stirrer. The container was heated in an oil bath at 80°C with a stirring rate of 1000 rpm for 2 hours until the system became a dark brown, transparent, non-layered viscous liquid, thus obtaining the choline chloride-lactic acid-glycerol eutectic solvent (NADES). If trace amounts of water or air bubbles need to be removed, the system can be treated in a vacuum drying oven at 45°C and -0.1 MPa for 2 hours. The difference lies in that 60mL of the prepared NADES was added to xylose and phenylalanine at a molar ratio of 1:1, and the total concentration of the substrate (xylose and phenylalanine) was controlled at 0.16mol / L. Reaction conditions: constant temperature stirring at 80°C for 2 hours to avoid side reactions caused by high temperature. After the reaction, 1mL of the reaction solution was diluted 10 times for LC-MS detection.

[0077] Example 14 Similar to Example 5, 60g of choline chloride, lactic acid, and glycerol were weighed in a 1:3:1 molar ratio and added to a three-necked flask or sealed glass container equipped with a magnetic stirrer. The container was heated in an oil bath at 80°C with a stirring rate of 1000 rpm for 2 hours until the system became a dark brown, transparent, non-layered viscous liquid, thus obtaining the choline chloride-lactic acid-glycerol eutectic solvent (NADES). If trace amounts of moisture or air bubbles need to be removed, the system can be treated in a vacuum drying oven at 45°C and -0.1 MPa for 2 hours. The difference lies in that 60mL of the prepared NADES was added to xylose and valine in a 1:1 molar ratio, and the total concentration of the substrate (xylose and valine) was controlled at 0.16 mol / L. Reaction conditions: constant temperature stirring at 80°C for 2 hours to avoid side reactions caused by high temperature. After the reaction, 1mL of the reaction solution was diluted 10 times for LC-MS detection.

[0078] Comparative Example 1 The procedure was carried out in accordance with Example 5, except that lactic acid was omitted. Instead, a eutectic solvent with a molar ratio of choline chloride and glycerol of 1:1 was used. A total of 60 g of choline chloride and glycerol was weighed, and after Nades was formed, 60 mL was measured, while keeping the total concentration of the substrate constant.

[0079] The results showed that when lactic acid was omitted, i.e., a eutectic solvent with a choline chloride to lactic acid molar ratio of 1:1 was used, and the total substrate concentration, NADES volume, and other reaction conditions remained unchanged, the final reaction system exhibited severe browning. In this case, the crude yield was only 29.01%.

[0080] Comparative Example 2 The procedure was carried out in accordance with Example 5, except that glycerol was omitted. Instead, a eutectic solvent with a molar ratio of choline chloride to lactic acid of 1:1 was used. A total of 60 g of choline chloride and lactic acid were weighed, and the total concentration of the substrate was kept constant.

[0081] The results showed that the reaction product was yellow, easily absorbed water, and turned into a caramel syrup-like substance.

[0082] Comparative Example 3 The procedure was carried out in accordance with Example 5, except that choline chloride was omitted. Instead, a eutectic solvent with a glycerol and lactic acid molar ratio of 1:1 was used. A total of 60g of glycerol and lactic acid was weighed, and the total concentration of the substrate was kept constant.

[0083] The results showed that no precipitation occurred in this system.

[0084] Comparative Example 4 The procedure was carried out in accordance with Example 5, except that choline chloride and glycerol were omitted, i.e., 60g of lactic acid was used as the solvent, and the total concentration of the substrate was kept constant.

[0085] The results showed that precipitation was difficult to occur in the lactic acid system.

[0086] Comparative Example 5 The procedure was carried out in accordance with Example 5, except that choline chloride and lactic acid were omitted, i.e., 60g of glycerol was used as the solvent, and the total concentration of the substrate was kept constant.

[0087] The results showed that the precipitated solids in the glycerol system were difficult to filter, and the product was dark in color. At this point, the crude yield was only 70.45%.

[0088] Comparative Example 6 The reaction was carried out according to Example 5, except that the reaction conditions were adjusted to 90°C.

[0089] The results showed that a large amount of melanoidins were generated in the reaction system, leading to a significant decrease in the yield of the target product. At this point, the crude yield was only 33.43%.

[0090] Comparative Example 7 The reaction was carried out according to Example 5, except that the reaction conditions were adjusted to 40°C.

[0091] The results showed that the reaction kinetics in the system were slow and the reaction efficiency was low. At this point, the crude yield was only 11.25%.

[0092] Comparative Example 8 The reaction was carried out in accordance with Example 5, except that the reaction time was adjusted to 1 hour.

[0093] The results showed that the reaction system was clear and light yellow, indicating a low degree of reaction.

[0094] Comparative Example 9 The reaction was carried out in accordance with Example 5, except that the reaction time was adjusted to 6 hours.

[0095] The results showed that the reaction system was dark brown, indicating that the reaction had largely entered the final stage and produced a large amount of melanoidins.

[0096] Table 1

[0097] From the perspective of key influencing factors, the proportion of NADES components plays a decisive role in the reaction process and product performance. Experiments show that lactic acid, as an acidic component, can effectively enhance the acidity of the system and inhibit browning during the reaction process by increasing its proportion, but at the same time, it will lead to a decrease in crude yield due to the dissolution of some products; glycerol mainly affects the viscosity of the system, and an increase in its proportion will increase the mass transfer resistance and reduce the reaction rate; choline chloride, as one of the core components of NADES, is crucial to the stability of the system and the formation of product precipitation. The results of Comparative Examples 1-5 show that the absence of any one of the components, such as choline chloride, lactic acid, or glycerol, results in obvious abnormalities in the reaction. Omitting lactic acid leads to severe browning of the system, with a crude yield of only 29%; omitting glycerol makes the product viscous and difficult to separate; omitting choline chloride results in no precipitation, while single lactic acid or glycerol systems have problems such as difficulty in precipitation and obstructed filtration, respectively. This confirms that the synergistic effect of the three components is a prerequisite for ensuring the smooth progress of the reaction and the product yield.

[0098] Reaction temperature and substrate type also significantly affected the experimental results. Below 40℃, the reaction efficiency was low; above 90℃, the yield of the target product decreased significantly. Therefore, 80℃ was the optimal reaction temperature determined experimentally. Regarding substrate type, reducing sugars (such as glucose and fructose) reacted more readily with amino acids than non-reducing sugars. The stronger the hydrophobicity of amino acids, the lower their solubility in the NADES system, leading to a slower reaction rate. The combination of glucose and arginine (molar ratio 1:1) exhibited good reaction compatibility.

[0099] In addition, the results of the free radical scavenging activity experiments (DPPH and ABTS free radical scavenging rates) are as follows: Figure 20 As shown, the Amadori compound prepared in this invention has free radical scavenging ability.

[0100] In summary, the component ratio, reaction temperature, and substrate type of choline chloride-lactic acid-glycerol NADES are the core factors for regulating the preparation efficiency, separation effect, and free radical scavenging activity of Amadori compounds. The reasonable matching of these three factors can achieve both efficient preparation of the target product and excellent performance, providing experimental basis for the green synthesis and antioxidant application of Amadori compounds.

[0101] The embodiments described above are not intended to limit the scope of this invention, nor are the steps described intended to limit the order of their execution. Any obvious modifications made to this invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims of this invention.

Claims

1. A eutectic solvent for preparing Amadori compounds, characterized in that, The eutectic solvent is composed of lactic acid, glycerol and choline chloride; the molar ratio of choline chloride, lactic acid and glycerol in the eutectic solvent is 1~2:1~6:1~3.

2. The eutectic solvent according to claim 1, characterized in that, The molar ratio of choline chloride, lactic acid and glycerol is selected from any of the following ratios: 1:1:1, 1:1:2, 1:1:3, 1:2:1, 1:3:1, 1:4:1, 2:1:1, 2:6:

3.

3. A method for preparing the eutectic solvent as described in claim 1, characterized in that, The preparation method is as follows: Take choline chloride, lactic acid and glycerol, mix them and then heat and stir until the system becomes a dark brown transparent viscous liquid without layering, thus obtaining the choline chloride-lactic acid-glycerol eutectic solvent; the heating temperature is 70~90℃ and the heating time is 1~5 hours.

4. A method for preparing Amadori compounds using the eutectic solvent of claim 1, characterized in that, The preparation method includes the following steps: (1) Synthesis of Amadori compounds: Take the above eutectic solvent, add sugar and acid, and then heat to react; (2) Product separation and purification: After the reaction is complete, methanol is added for dilution, and then ethanol is added for precipitation. After filtration, the precipitate is collected to obtain the Amadori compound.

5. The method according to claim 4, characterized in that, The sugar in step (1) includes glucose or xylose.

6. The method according to claim 4, characterized in that, The acid in step (1) includes arginine, phenylalanine, leucine, methionine, or valine.

7. The method according to claim 4, characterized in that, In step (1), the molar ratio of sugar to acid is 1:0.1~10.

8. The method according to claim 4, characterized in that, In step (1), the total concentration of sugar and acid in the eutectic solvent is 0.1~0.5 mol / L.

9. The method according to claim 4, characterized in that, In step (1), the heating reaction temperature is 70~90℃ and the time is 1~3 hours.

10. The method according to claim 4, characterized in that, In step (1), ethanol is replaced with acetone.

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