A terminal hydroxyl group thioalkyl alpha-cyclodextrin sulfate ester derivative, and a synthesis method and application thereof

Abstract

The application discloses a kind of terminal hydroxyl group thioalkyl alpha-cyclodextrin sulfate ester derivatives and synthesis method and application, belong to alpha-cyclodextrin derivative technical field.The application is successfully prepared by introducing high hydrophilic group into alpha-cyclodextrin structure, compound 1-6 and compound 2-4, method is simple and efficient, process controllable, high purity easy preparation;Prepared compound 1-6 and compound 2-4 are simulated HSPG structure, competitive binding RSV, IAV, CoV virus envelope protein, through the synergistic effect of multivalent sulfonic acid and alkyl chain, block virus adsorption, irreversible damage virus structure, realize broad-spectrum antiviral effect of respiratory virus;The synthesis method of terminal hydroxyl group thioalkyl alpha-cyclodextrin sulfate ester derivative established by the application can prepare target derivative with different degree of substitution, and has antiviral effect, provides theoretical support for the application of alpha-cyclodextrin derivative in biological and medical fields.

Description

Technical Field

[0001] This invention relates to the field of α-cyclodextrin derivatives, and in particular to a terminal hydroxyl thioalkyl α-cyclodextrin sulfate derivative, its synthesis method, and its application. Background Technology

[0002] In recent years, α-cyclodextrin (α-CD) has attracted attention from various fields due to its excellent physicochemical properties and unique effects. α-CD is a substance obtained by the decomposition of amylose under the catalysis of cyclodextrin glucosyltransferase (CGTase). Its structure consists of six D-glucanopyranoside units linked end-to-end by α-1,4 glycosidic bonds, forming a closed hollow ring molecule, belonging to macrocyclic compounds. As a naturally occurring glucose oligomer derivative, cyclodextrin is non-toxic to humans, has good water solubility and biocompatibility, and has wide applications in food, pharmaceuticals, nanomaterials, and environmental fields.

[0003] The internal cavity of α-CD is smaller than that of β-cyclodextrin (β-CD), a structural feature that makes it more adept at forming inclusion complexes with small molecules. Furthermore, α-CD exhibits superior water solubility compared to β-CD, making it more practical for applications requiring highly soluble cyclodextrins. In the fields of functional foods and pharmaceutical excipients, α-CD is not only used as a soluble dietary fiber or a raw material for improving metabolic syndrome, but its functions in lowering blood sugar and aiding weight loss have also been scientifically validated and recognized by the market.

[0004] The C6 primary hydroxyl group of the glucose unit in cyclodextrin exhibits the highest nucleophilic activity and is the core reaction site for the selective chemical modification of most derivatives. Existing cyclodextrin derivatives are mainly classified into ester derivatives, ether derivatives, deoxygenated derivatives, and special modified derivatives grafted with specific functional groups. However, existing modification schemes are mostly limited to monosubstituted and short carbon chain linker structures, resulting in cyclodextrin derivatives with limited functions, suitable only for basic applications such as drug solubilization, enzyme immobilization, and chiral separation.

[0005] Due to the diverse biological activities and widespread tissue distribution of heparin sulfate proteoglycans (HSPGs), most pathogenic microorganisms (especially viruses) can use them as docking sites on the surface of eukaryotic cells to invade host cells. Studies have shown that HSPGs play a crucial role in promoting the attachment of herpes simplex virus (HSV) to the cell surface and its effective entry into cells. Therefore, by blocking HSV adsorption to cells, the cellular susceptibility to the virus can be reduced, thereby enhancing the cell's antiviral capacity. Furthermore, the long-chain sulfonic acid groups can interact with the viral surface through strong multivalent binding, causing local distortion and deformation of viral particles, thus irreversibly losing their infectivity, enhancing the antiviral activity of drugs, and improving their ability to combat drug resistance. Summary of the Invention

[0006] The purpose of this invention is to provide a hydroxyl-terminated thioalkyl α-cyclodextrin sulfate derivative, its synthesis method, and its application. This method can prepare α-cyclodextrin derivatives with different degrees of substitution, which have antiviral effects and good biocompatibility. The method is simple, efficient, and produces few byproducts.

[0007] To achieve the above objectives, the present invention provides a terminal hydroxyl thioalkyl α-cyclodextrin sulfate derivative, wherein the terminal hydroxyl thioalkyl α-cyclodextrin sulfate derivative is compound 1-6 and compound 2-4; The structural formulas of compounds 1-6 are as follows: ; The structural formula of compounds 2-4 is: .

[0008] The method for synthesizing a terminal hydroxyl thioalkyl α-cyclodextrin sulfate derivative as described above is characterized by: using α-cyclodextrin as the starting material, and obtaining it by introducing highly hydrophilic groups into the α-cyclodextrin structure.

[0009] Preferably, the steps for preparing compounds 1-6 are as follows: S1. Vacuum-dried α-cyclodextrin, tert-butyldimethylchlorosilane and imidazole were placed in the same container and subjected to anhydrous and oxygen-free operation. Anhydrous dimethylformamide was added under a protective atmosphere. After all components were completely dissolved, the reaction was carried out under a protective atmosphere. The reaction solution was then poured into ice water and filtered. The precipitate was collected, washed with ice water and dried to obtain crude compound 1-1. S2. The crude compound 1-1 prepared in S1 and sodium hydride were subjected to anhydrous and oxygen-free operation. Then, anhydrous dimethylformamide was slowly added and reacted until a grayish-white "cloud"-like substance appeared. Iodomethane was then added dropwise under ice-water bath conditions until the grayish-white "cloud"-like substance disappeared. The reaction was continued and then transferred to room temperature with stirring. After the reaction was completed, the mixture was cooled to 0°C, and methanol was added dropwise until no bubbles were produced. After removing the methanol, dichloromethane was added to the reaction system. The mixture was then washed with deionized water, sodium thiosulfate solution, and deionized water in sequence. After separating the organic phase, the mixture was dried, filtered, and purified to obtain compound 1-2. S3. Compound 1-2 obtained in S2, ammonium fluoride, and anhydrous methanol are heated and refluxed until the reaction is complete. After removing the solvent, dichloromethane is added and sonicated. After filtration, solvent removal, and purification, compound 1-3 is obtained. S4. Compounds 1-3 obtained in S3 and sodium hydride were subjected to anhydrous and oxygen-free operation. Then, anhydrous dimethylformamide was added under ice bath conditions. After stirring at 0°C, allyl bromide was added to continue the reaction. Then, the reaction was transferred to room temperature and stirred until the reaction was completed. After cooling to 0°C, methanol was added dropwise until no more bubbles were produced. After removing the methanol, dichloromethane was added to the reaction system. After the reaction, the system was washed with deionized water, sodium thiosulfate solution, and deionized water in sequence. The organic phase was separated and dried, the organic solvent was removed, and the system was purified to obtain compounds 1-4. S5. Compounds 1-4 obtained in S4, 11-mercapto-1-undecanol, and anhydrous methanol were added to the same reaction vessel and stirred until completely dissolved. Then, azobisisobutyronitrile was added, and the mixture was stirred and heated under reflux. Azobisisobutyronitrile was added during the reaction. After the reaction was completed, the solvent was removed, excess 11-mercapto-1-undecanol was recovered, and the mixture was purified and separated to obtain compounds 1-5. S6. Compounds 1-5 obtained in S5 and sulfur trioxide pyridine were placed in the same container and subjected to anhydrous and oxygen-free operation. Then anhydrous tetrahydrofuran was added, and the reaction was carried out under constant temperature and stirring. After removing the solvent, the pH of the solution in the reaction system was adjusted to 9-10. After a pale yellow solid gradually precipitated out, sodium chloride solid was added. After the pale yellow solid was completely precipitated, it was filtered. The pale yellow solid was dissolved in methanol, and the sodium chloride was removed by centrifugation. Then the methanol was removed, and the product was dried to obtain compounds 1-6.

[0010] Preferably, in S1, the mass-to-volume ratio of α-cyclodextrin: tert-butyldimethylchlorosilane: imidazole: anhydrous dimethylformamide is 1g:1g:1g:23-24mL; in S2, the mass-to-volume ratio of compound 1-1: sodium hydride: anhydrous dimethylformamide: iodomethane: dichloromethane is 2.5g:3.3g:100mL:3.75mL:60mL; and in S3, the mass-to-volume ratio of compound 1-2: ammonium fluoride: anhydrous methanol: dichloromethane is 1g:0.72g:80mL:30mL. The mass-to-volume ratio of compounds 1-3 in S4: sodium hydride: anhydrous dimethylformamide: allyl bromide: dichloromethane is 0.6 g: 0.66 g: 35 mL: 2 mL: 30 mL; the mass-to-volume ratio of compounds 1-4 in S5: 11-mercapto-1-undecanol: anhydrous methanol: azobisisobutyronitrile is 0.2 g: 0.192 g: 35 mL: 0.02 g; the mass-to-volume ratio of compounds 1-5 in S6: sulfur trioxide pyridine: anhydrous tetrahydrofuran is 0.13 g: 0.08 g: 20 mL.

[0011] Preferably, in S2 and S4, the water is washed 3-5 times with deionized water and 2-3 times with sodium thiosulfate solution, and the amount of deionized water and sodium thiosulfate solution added during washing is 1-2 times the volume of the reaction system; the purification in S2-S5 is carried out by silica gel column chromatography.

[0012] Preferably, in step S3, the heating conditions are 70-80℃; the ultrasonic treatment is performed at 40kHz for 5-15 minutes; in step S4, after adding anhydrous dimethylformamide, the reaction is stirred for 0.5-1.5 hours, and after adding allyl bromide, the reaction is performed for 0.5-1.5 hours; in step S5, after adding azobisisobutyronitrile, it is added every 30 minutes, and the reaction is carried out under reflux at 70-80℃ for 12 hours; after adding anhydrous tetrahydrofuran, the reaction is heated and stirred at 40℃ for 72 hours; in step S6, after adding anhydrous tetrahydrofuran, the reaction is heated and stirred at 35-45℃.

[0013] Preferably, the steps for preparing compounds 2-4 are as follows: S(1) Place α-cyclodextrin, barium hydroxide octahydrate, and barium oxide in the same reaction vessel, use nitrogen as a protective gas, and then add anhydrous dimethylformamide and allyl bromide to the reaction system. After the system reacts in an ice-water bath, transfer it to room temperature for stirring. Then add ammonia water to the system and stir. After the reaction is complete, add dichloromethane to fully dissolve the product. After washing with deionized water, separate the organic phase, and then dry, filter, and purify it to obtain the crude product of compound 2-1. S(2) The crude compound 2-1 prepared by S(1) and sodium hydride were subjected to anhydrous and oxygen-free operation. Then anhydrous dimethylformamide was added and stirred to react. Then iodomethane was added and stirred to react. After returning to room temperature, stirring was continued until the reaction was completed. Methanol was added under an ice-water bath until no gas was produced. After recovering the solvent, dichloromethane was added to the reaction system. Then the system was washed with deionized water, sodium thiosulfate solution and deionized water in sequence. After separating the organic phase, the system was dried, filtered and purified to obtain compound 2-2. S(3) Add compound 2-2 obtained from S(2), 11-mercapto-1-undecanol, anhydrous methanol, and azobisisobutyronitrile to the same reaction vessel. After all the compounds are dissolved, stir and heat under reflux. During the reaction, azobisisobutyronitrile is added. After the reaction is completed, remove the solvent and purify and separate to obtain compound 2-3. S(4) and the compounds 2-3 and sulfur trioxide pyridine obtained from S(3) were placed in the same container for anhydrous and oxygen-free operation. Then anhydrous tetrahydrofuran was added, and the mixture was heated and stirred under constant temperature until the reaction was completed. The tetrahydrofuran solvent was removed, and the pH of the solution in the reaction system was adjusted to 9-10. After a pale yellow solid gradually precipitated, sodium chloride solid was added. After the pale yellow solid was completely precipitated, it was filtered. The pale yellow solid was dissolved in methanol, and the sodium chloride was removed by centrifugation. Then the methanol was removed, and the mixture was dried to obtain compound 2-4.

[0014] Preferably, in S(1), the mass-to-volume ratio of α-cyclodextrin:barium hydroxide octahydrate:barium oxide:anhydrous dimethylformamide:allyl bromide is 1g:5g:5g:30mL:6mL; in S(2), the mass-to-volume ratio of compound 2-1:sodium hydride:anhydrous dimethylformamide:iodomethane:dichloromethane is 1g:0.35g:30mL:2mL:30mL; in S(3), the mass-to-volume ratio of compound 2-2:11-mercapto-1-undecanol:anhydrous methanol:azobisisobutyronitrile is 0.2g:0.4g:40mL:0.02g; and in S(4), the mass-to-volume ratio of compound 2-3:sulfur trioxide pyridine:anhydrous tetrahydrofuran is 0.269g:0.161g:20mL.

[0015] Preferably, the ammonia water added in S(1) has a mass fraction of 28%; the amount of deionized water added during washing is 1-2 times the volume of the reaction system; after all the contents of S(3) are dissolved, the mixture is stirred and heated under reflux at 70-80°C, and the reaction is monitored by TLC until it is complete; azobisisobutyronitrile is added every 30 minutes; after anhydrous tetrahydrofuran is added to S(4), the mixture is heated and stirred at 40°C, and the reaction is monitored by TLC until it is complete.

[0016] The application of terminal hydroxyl thioalkyl α-cyclodextrin sulfate derivatives as described above in the preparation of antiviral agents.

[0017] Therefore, the present invention provides a hydroxyl-terminated thioalkyl α-cyclodextrin sulfate derivative, its synthesis method, and its application, with the following specific technical effects: (1) By using α-cyclodextrin as the core and introducing highly hydrophilic groups into its structure, the present invention successfully prepared two new α-cyclodextrin derivatives, which are hydroxyl-terminated thioalkyl α-cyclodextrin sulfate derivatives, namely compounds 1-6 and compounds 2-4. (2) The method for synthesizing α-cyclodextrin sulfate derivatives with terminal hydroxyl thioalkyl groups established by the present invention can prepare target derivatives with different degrees of substitution by controlling the length of the alkyl carbon chain and the number of sulfate groups. The method is simple and efficient, the process is controllable, the purity is high and easy to prepare, and there are few by-products. (3) The compounds 1-6 and 2-4 prepared in this invention can inhibit the adsorption and mediation of HSPG on viruses and produce an inhibitory effect on respiratory viruses (RSV, IAV, CoV). Specifically, by using a selective protection-methylation-deprotection strategy, the modification sites on one side are retained, a hydrophilic α-cyclodextrin rigid skeleton homologous to the HSPG polysaccharide backbone is constructed, a long hydrophobic alkyl side chain is introduced to simulate the hydrophobic structure of HSPG anchoring the cell membrane, and sulfur trioxide pyridine is used for terminal sulfation modification, so that the compounds can competitively replace cell membrane HSPG to preferentially bind respiratory virus envelope glycoproteins, thereby blocking virus adsorption. At the same time, the synergistic effect of polyvalent sulfonic acid and hydrophobic alkyl leads to local distortion of virus particles and irreversible destruction of virus particles, thereby achieving the effect of anti-respiratory virus. (4) The present invention provides a method for synthesizing α-cyclodextrin sulfate derivatives with terminal hydroxyl thioalkyl groups, which effectively improves their biocompatibility and provides theoretical support for the application of α-cyclodextrin derivatives in the fields of biology and medicine.

[0018] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 These are the proton nuclear magnetic resonance spectra of compounds 1-6. 1 H NMR spectrum; Figure 2 These are the carbon nuclear magnetic resonance spectra of compounds 1-6. 13 C NMR spectrum; Figure 3 These are the Fourier transform infrared (FT-IR) spectra of compounds 1-6; Figure 4 These are the electrospray ionization mass spectra (ESIMS) of compounds 1-6; Figure 5 It is the proton nuclear magnetic resonance spectrum of compounds 2-4 ( 1 H NMR spectrum; Figure 6 The carbon nuclear magnetic resonance spectra of compounds 2-4 ( 13 C NMR spectrum; Figure 7 These are the Fourier transform infrared (FT-IR) spectra of compounds 2-4; Figure 8 This is the electrospray ionization mass spectrum (ESIMS) of compounds 2-4; Figure 9 This is a graph showing the cell viability of Hep-2 cells after treatment with different concentrations of CD-1 and CD-2. Figure 10 These are RT-qPCR and Western blot results for the detection of CD-1 and CD-2 anti-RSV activities. Figure 11 This is a graph showing the cell viability of A549 cells treated with different concentrations of CD-1 and CD-2. Figure 12 These are RT-qPCR and Western blot results of CD-1 and CD-2 anti-IAV activities. Figure 13 This is a graph showing the cell viability of Huh7.5 cells treated with different concentrations of CD-1 and CD-2. Figure 14 This is an image showing the RT-qPCR and Western blot detection of CD-1 and CD-2 anti-HCoV-229E activities. Detailed Implementation

[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] To make the objectives, technical solutions, and advantages of this application clearer, more thorough, and more complete, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. The following detailed descriptions are all descriptions of embodiments, intended to provide further detailed explanation of the present invention. Unless otherwise specified, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0023] The instruments, equipment, reagents, and materials used in the examples were all obtained commercially.

[0024] Example 1 The synthetic routes for compounds 1-6 are shown below: (1) Synthesize compound 1-1.

[0025] α-Cyclodextrin was dried to constant weight in a vacuum oven at 100°C. 3.0 g of dried α-cyclodextrin, 3.0 g of tert-butyldimethylchlorosilane, and 3.0 g of imidazole were accurately weighed and placed in a clean reaction flask under anhydrous and oxygen-free conditions. 70 mL of anhydrous dimethylformamide (DMF) was added to the reaction flask under nitrogen protection, ensuring that all reactants were completely dissolved and thoroughly mixed. The reaction was carried out at room temperature under nitrogen protection, and the reaction progress was monitored by thin-layer chromatography (TLC). The reaction was considered complete when α-cyclodextrin completely disappeared and a new product R appeared. f The concentration of the reagent was 0.42 and other substances (dichloromethane:methanol:water volume ratio = 50:10:1, chromatography plate model: Huanghai brand HSGF254), and the reaction was continued for 0.5 h.

[0026] Then, while stirring, the obtained mixture was slowly poured into 500 mL of ice water, filtered using a vacuum filter, and the resulting white precipitate was collected. The precipitate was then washed five times with ice water (50 mL each time) and dried under natural environmental conditions to obtain the crude product of compound 1-1.

[0027] (2) Synthesis of compounds 1-2.

[0028] Weigh 2.5g of the crude compound 1-1 obtained in step (1) and 3.3g of sodium hydride (40% oil content) (the molar ratio of crude compound 1-1 to sodium hydride is 1:24), and place them in a 250mL round-bottom flask for anhydrous and oxygen-free operation with nitrogen as the protective gas. Under an ice-water bath, slowly add 100mL of anhydrous DMF using a syringe and continue the reaction for 1.5h. During this period, a grayish-white "cloud"-like substance will appear. After the reaction is complete, slowly add 3.75mL of iodomethane to the flask under an ice-water bath. The "cloud"-like substance disappears. After reacting for 1h, transfer the flask to room temperature and stir the reaction. Monitor the reaction progress by TLC. After the reaction is complete, cool the reaction flask to 0℃ and add methanol dropwise until no more bubbles are produced in the reaction flask.

[0029] After removing methanol by vacuum distillation, 60 mL of dichloromethane was added to the residue, mixed well, and washed with 30 mL of deionized water each time. The residue was then washed twice with 30 mL of sodium thiosulfate aqueous solution each time, followed by one wash with deionized water. The organic phase was separated, dried over 2 g of anhydrous sodium sulfate for 30 min, filtered, and concentrated. Purification and separation were then performed using silica gel column chromatography with 300 mesh silica gel powder and a gradient elution buffer (dichloromethane:methanol volume ratio = 80:1-65:1). The final product was 2.27 g of white powder solid, which is compound 1-2.

[0030] The overall yield, calculated from the two-step chemical reaction, is 82.6%, R. fThe value is 0.48 (dichloromethane:methanol volume ratio = 20:1, chromatography plate model: Huanghai brand HSGF254).

[0031] (3) Synthesize compounds 1-3.

[0032] 1g of compound 1-2 obtained in step (2) and 0.72g of ammonium fluoride were weighed and added to a 200mL round-bottom flask (molar ratio of compound 1-2 to ammonium fluoride = 1:24). Then 80mL of anhydrous methanol was added, and the mixture was stirred and refluxed in an oil bath at 75℃ for 24h. The reaction progress was monitored by TLC. After the reaction was completed, the solvent was removed by vacuum distillation.

[0033] Then, 30 mL of dichloromethane was added to the reaction flask and sonicated for 10 min. Excess ammonium fluoride and other substances were removed by filtration. The solvent was removed by vacuum distillation. Purification and separation were performed using silica gel column chromatography with 300 mesh silica gel powder and gradient elution (dichloromethane:methanol volume ratio = 10:1-4:1). Finally, 0.55 g of pale yellow crystals, namely compounds 1-3, were obtained. The yield was 89.4%. f The value is 0.39 (dichloromethane:methanol volume ratio = 4:1, chromatography plate model: Huanghai brand HSGF254).

[0034] (4) Synthesize compounds 1-4.

[0035] Accurately weigh 0.60 g of compound 1-3 obtained in step (3) and 0.33 g of sodium hydride (40% oil content) (molar ratio of compound 1-3 to sodium hydride = 1:10) and add them to a 100 mL round-bottom flask. Perform the reaction in an anhydrous and oxygen-free environment with nitrogen as the protective gas. Under an ice-water bath, add 35 mL of anhydrous DMF to the reaction flask using a syringe and stir at 0 °C for 1 h. Add 2 mL of allyl bromide to the flask using a syringe (molar ratio of compound 1-3 to allyl bromide = 1:8) and react at 0 °C for 1 h. Then, transfer the reaction flask to room temperature and stir (300 rpm) for 50 h. Monitor the reaction by TLC. When the reaction is complete, cool the reaction flask to 0 °C and add methanol dropwise until no more bubbles are produced in the reaction flask.

[0036] Methanol was removed by vacuum distillation. Then, 30 mL of dichloromethane was added to the reaction flask, mixed, and washed three times with deionized water (15 mL each time). The mixture was then washed twice with 0.01 mol / L sodium thiosulfate aqueous solution (15 mL each time), followed by one wash with deionized water to separate the organic phase. 1.5 g of anhydrous sodium sulfate was weighed and added to the organic layer, stirred thoroughly, and allowed to stand and dry for 0.5 h. The drying agent was then removed by filtration. The solvent was removed by vacuum distillation, and purification and separation were performed by silica gel column chromatography (300 mesh silica gel powder). The eluent (dichloromethane:methanol volume ratio = 80:1-60:1) yielded 572 mg of a pale yellow solid, which was compounds 1-4. The yield was 78.8%. The R of the target product after washing was... f The value is 0.43 (dichloromethane:methanol volume ratio = 20:1, chromatography plate model: Huanghai brand HSGF254).

[0037] (5) Synthesize compounds 1-5.

[0038] Accurately weigh 200 mg of compounds 1-4 obtained in step (4) and 192 mg of 11-mercapto-1-undecanol (molar ratio of compounds 1-4 to 11-mercapto-1-undecanol = 1:10) and add them to a 100 mL two-necked flask. Add 35 mL of anhydrous methanol to the two-necked flask and stir until the solids are completely dissolved. Then add 20 mg of azobisisobutyronitrile (AIBN) that has been cooled to room temperature. Place the two-necked flask in an oil bath at 80 °C and reflux for 12 h with stirring at 300 rpm. During the reaction, add 5 mg of AIBN initiator to the flask every 30 min. Simultaneously, the reaction progress was monitored by TLC. After the reaction was completed, the solvent was removed by vacuum distillation, followed by column chromatography to recover excess 11-mercapto-1-undecyl alcohol for the next reaction. Purification was performed by silica gel column chromatography using 300-mesh silica gel powder and a gradient elution buffer of dichloromethane:methanol (volume ratio = 60:1-30:1). The final product was 196 mg of a pale yellow oily solid, which was compounds 1-5. Yield: 51.9%, R f The value is 0.5 (dichloromethane:methanol volume ratio = 15:1, chromatography plate model: Huanghai brand HSGF254).

[0039] (6) Synthesize compounds 1-6.

[0040] Weigh 130 mg of compounds 1-5 obtained in step (5) and 80 mg of pyridine sulfur trioxide (C5H5N·SO3) (molar ratio of compounds 1-5 to pyridine sulfur trioxide = 1:10), and add them to a 50 mL round-bottom flask (reaction flask). Perform anhydrous and oxygen-free operation with nitrogen as the protective gas. Add 20 mL of anhydrous tetrahydrofuran (THF) to the reaction flask using a syringe. Place the reaction flask in a constant temperature environment of 40 °C, stir the reaction for 72 h, and then remove the solvent by vacuum distillation. Then, use sodium hydroxide solution to adjust the pH of the solution in the reaction flask to 9-10. After a pale yellow solid gradually precipitates, add sodium chloride solid until the pale yellow solid is completely precipitated (the amount of precipitation no longer increases), and then filter. Dissolve the obtained pale yellow solid in methanol, centrifuge to remove sodium chloride that is insoluble in methanol, and then remove methanol by vacuum distillation. After the residue is dried naturally, 90 mg of pale yellow solid is obtained, which is compound 1-6, with a yield of 58.3%.

[0041] The structures of compounds 1-6 were confirmed. 1 The H NMR results are as follows Figure 1 As shown, 13 The C NMR results are as follows Figure 2 As shown, the FT-IR results are as follows: Figure 3 As shown, the ESIMS results are as follows: Figure 4 As shown, the product is a hydroxyl-terminated thioalkyl α-cyclodextrin sulfate derivative.

[0042] 1 H NMR: (600MHz, Methanol-d4)δ5.06(m,6H),3.84(d,J=6.5Hz,12H),3.68(m,12H), 3.64(m,24H),3.54(t,J=7.8Hz,18H),3.50(m,24H),3.10(d,J=9.9Hz,12H),2 .97–2.89(m,6H),2.84(dt,J=13.9,6.7Hz,12H),2.76(dt,J=13.7,6.1Hz,6H) ,2.05(s,12H),1.77(d,J=9.5Hz,12H),1.52(d,J=7.2Hz,24H),1.34(s,72H).

[0043] 13 C NMR: (150MHz, Methanol-d4) δ99.15,82.16,82.03,71.27,70.72,69.66,67.92,60.79,57.73,31.88,29.65,29.42,29.13,28.81,28.44,25.58.

[0044] FT-IR: 2929.79cm -1 2852.62cm -1 1448.24cm -1 1256.69cm -1 1131.09cm -1 1031.73cm -1 811.62cm -1 630.25cm -1 581.89cm -1 .

[0045] ESIMS: m / z 513.3899 [M-6Na] + ]6-.

[0046] Example 2 The synthetic routes for compounds 2-4 are shown below: (1) Synthesize compound 2-1.

[0047] Weigh 1 g of α-cyclodextrin, 5 g of barium hydroxide octahydrate (BaO·8H2O), and 5 g of barium oxide (BaO) into a 200 mL flask (reaction flask) under nitrogen as a protective gas. Add 30 mL of DMF to the reaction flask using a syringe, followed by 6 mL of allyl bromide (DMF:allyl bromide molar ratio = 1:15). React in an ice-water bath for 1 h, then transfer to room temperature and stir for another 48 h. Next, add 20 mL of 28% ammonia solution and stir for 0.5 h. Transfer the reaction solution to a separatory funnel, add 100 mL of dichloromethane to fully dissolve the product, and wash five times with 30 mL of deionized water each time. Separate the organic phase, dry with 2 g of anhydrous sodium sulfate for 0.5 h, and then filter and concentrate. Purification and separation were performed using silica gel column chromatography with 300-mesh silica gel powder. The eluent was prepared as hexane and ethyl acetate in a 1:1 volume ratio, yielding 0.80 g of a colorless, transparent substance, which was compound 2-1. The yield was 53.3%. f The value is 0.49 (hexane: ethyl acetate volume ratio = 1:1, chromatography plate model: Huanghai brand HSGF254).

[0048] (2) Synthesize compound 2-2.

[0049] Weigh 1g of compound 2-1 prepared in step (1) and 0.35g of sodium hydride, add them to a 200mL flask, and perform anhydrous and oxygen-free operation with nitrogen as the protective gas. Under ice-water bath, add 30mL of anhydrous DMF, stir and react for 1h, then add 2mL of iodomethane, stir and react for 1h, then return to room temperature and continue stirring for 3.5h.

[0050] After the reaction was complete, methanol was slowly added to the reaction flask under an ice-water bath until no more gas was produced. The solvent was then recovered by rotary evaporation. 30 mL of dichloromethane was added to the solid residue, and the mixture was washed three times with 20 mL of deionized water each time. It was then washed three times with 0.1 mol / L sodium thiosulfate solution, followed by one wash with deionized water. The organic phase was separated, dried with anhydrous sodium sulfate, filtered to remove the drying agent, and the solvent was recovered by rotary evaporation. Purification and separation were performed by silica gel column chromatography using 300 mesh silica gel powder. The eluent ratio was n-hexane:ethyl acetate (volume ratio) of 8:1–4:1, yielding 828 mg of colorless solid, which was compound 2-2. The yield was 62.5%. f The value is 0.50 (hexane:ethyl acetate volume ratio = 2:1, chromatography plate model: Huanghai brand HSGF254).

[0051] (3) Synthesize compound 2-3.

[0052] Weigh 200 mg of compound 2-2 obtained in step (2) and 400 mg of 11-mercapto-1-undecanol (molar ratio of compound 2-2 to 11-mercapto-1-undecanol = 1:15), add them to a 100 mL double-necked flask, then add 40 mL of anhydrous methanol and 20 mg of AIBN that has been restored to room temperature. After the solid is completely dissolved, place it in a 75 °C oil bath and heat and stir under reflux. Add 5 mg of AIBN to the flask every 30 min, and the entire reaction process lasts for 12 h. At the same time, the reaction progress is monitored by TLC. After the reaction is completed, the solvent is removed by vacuum distillation, and then purified and separated by silica gel column chromatography. The silica gel powder used is 300 mesh, and the excess 11-mercapto-1-undecanol is recovered. The eluent is eluted with a gradient (dichloromethane:methanol volume ratio = 70:1-20:1) to obtain 269 mg of solid, which is compound 2-3. Yield 51.9%, R f The value is 0.45 (dichloromethane:methanol volume ratio = 15:1, chromatography plate model: Huanghai brand HSGF254).

[0053] (4) Synthesize compounds 2-4.

[0054] Weigh 269 mg of compound 2-3 obtained in step (3) and 161 mg of pyridine sulfur trioxide (C5H5N·SO3) (molar ratio of compound 2-3 to pyridine sulfur trioxide = 1:15), and add them to a 50 mL round-bottom flask (reaction flask). Perform the reaction under anhydrous and oxygen-free conditions, using nitrogen as a protective gas. Add 20 mL of anhydrous THF to the reaction flask using a syringe. Then place the reaction flask in a constant temperature environment of 40 °C and heat and stir at 40 °C for 72 h.

[0055] After the reaction was complete, the tetrahydrofuran solvent was removed by vacuum distillation. Then, the pH of the solution in the reaction flask was adjusted to 9-10 using sodium hydroxide solution, and a pale yellow solid gradually precipitated out. Sodium chloride was added to completely precipitate the pale yellow solid, and the mixture was filtered. The obtained pale yellow solid was dissolved in methanol, and the insoluble sodium chloride was removed by centrifugation. The methanol was then removed by vacuum distillation. The residue was dried naturally to obtain 172 mg of yellow solid, which was compound 2-4, with a yield of 51.6%.

[0056] The structures of compounds 2-4 were confirmed. 1 The H NMR results are as follows Figure 5 As shown, 13 The C NMR results are as follows Figure 6 As shown, the FT-IR results are as follows: Figure 7 As shown, the ESIMS results are as follows: Figure 8 As shown, the product is a hydroxyl-terminated thioalkyl α-cyclodextrin sulfate derivative.

[0057] 1 H NMR: (600MHz, Methanol-d4)δ5.03(d,J=3.9Hz,6H),3.86(d,J=7.1Hz,24H),3.66(m,48H),3.54(m,24H),3.09(m ,6H),2.93(m,12H),2.84(m,24H),2.79(m,12H),2.04(s,24H),1.78(s,24H),1.53(s,48H),1.34(s,144H).

[0058] 13 C NMR: (150MHz,Methanol-d4)δ98.59,82.56,80.86,80.71,71.76,70.01,69.55,6 7.84,60.90,31.65,30.61,29.96,29.82,29.40,29.14,28.64,28.39,25.58.

[0059] FT-IR: 2927.67cm -1 2852.62cm -1 1466.21cm -1 1359.97cm -1 1261.53cm -1 1161.76cm -1 1035.96cm -1 800.22cm -1 557.61cm -1 .

[0060] ESIMS: [M-12Na] + ]12-=411.5034.

[0061] Example 3 The antiviral activity of the prepared compounds 1-6 (hexa(6-oxo-(propanedecyl thioether-1-sulfate sodium)-2,3-oxo-methyl)-α-cyclodextrin; CD-1) and 2-4 (hexa(2,6-oxo-(propanedecyl thioether-1-sulfate sodium)-3-oxo-methyl)-α-cyclodextrin; CD-2) was investigated, as follows: (1) Detection of anti-respiratory syncytial virus (RSV) activity.

[0062] Detection of CD-1 and CD-2 cytotoxicity against Hep2 cells: Different concentrations of CD-1 and CD-2 were added to Hep2 cells, mixed thoroughly, and incubated at room temperature for 48 hours. Cytotoxicity was then detected using a CCK-8 assay kit. Results are as follows: Figure 9 As shown, CD-2 (TC0 = 100 μg / mL, TC) 50 >200μg / mL) compared to CD-1 (TC0=50μg / mL, TC 50 The concentration of 142.91 μg / mL showed lower cytotoxicity, providing a safety basis for its antiviral application at higher doses.

[0063] Therefore, the maximum concentration of CD-1 used in subsequent cell experiments was 50 μg / mL, and the maximum concentration of CD-2 used in subsequent cell experiments was 100 μg / mL. At these concentrations, the compounds did not have cytotoxic effects.

[0064] Hep2 cells are widely used for screening anti-RSV drugs due to their high sensitivity to RSV and ability to stably support viral replication. To evaluate the anti-RSV activity of CD-1 and CD-2, in vitro pharmacodynamic experiments were conducted using a Hep2 cell model. Hep2 cells were seeded in 24-well plates (5 × 10⁻⁶ cells / well). 4(cells / well) When the cell density reached 70%, different concentrations of CD-1 or CD-2 were added to the drug-treated groups, while 50 nM Palivizumab (a commercially available anti-RSV monoclonal antibody) was added to the positive control group. After mixing, the cells were incubated at room temperature for 6 h (pretreatment). After pretreatment, RSV virus was inoculated (MOI=0.01), and different concentrations of the drug were added to the drug-treated groups simultaneously. After 48 h, total RNA and protein were extracted from the cells. The content of viral RNA (RSV M2 gene RNA) was detected by RT-qPCR, and the content of viral protein (RSV G protein) was detected by Western blot.

[0065] RT-qPCR results are as follows Figure 10 As shown in A and B, the Western blot results are as follows: Figure 10 As shown in C and D, in Hep2 cells, both RT-qPCR and Western blot data indicated that the positive control drug Palivizumab had significant anti-RSV activity, with viral protein expression and RNA copy number decreasing by more than 95% compared to the viral control group, consistent with reported results in the literature, demonstrating the reliability of the experimental system. CD-1 and CD-2 can dose-dependently reduce the expression of RSV RNA and protein, and CD-1 has an EC50-like effect on RSV RNA. 50 The EC50 of CD-2 against RSV RNA was 15.16 ± 6.99 μg / mL. 50 The concentration was 7.63 ± 0.85 μg / mL. CD-2 showed particularly strong inhibitory effects, achieving an inhibition rate of over 95% against viral RNA at concentrations >25 μg / mL. In contrast, CD-1 showed an inhibition rate of approximately 70% at the same concentration, suggesting that CD-2 may have a stronger anti-RSV effect.

[0066] (2) Anti-influenza virus (IAV) activity detection.

[0067] Different concentrations of CD-1 and CD-2 were added to A549 cells, mixed well, and incubated at room temperature for 48 hours. Cytotoxicity was then detected using a CCK-8 assay kit. Results are as follows: Figure 11 As shown, CD-1 in A549 cells TC 50 =151.75 μg / mL, TC0=100 μg / mL, TC of CD-2 in A549 cells 50 >200 μg / mL, TC0>200 μg / mL. The maximum concentration of CD-1 and CD-2 used in subsequent pharmacodynamic studies was 100 μg / mL, at which the compounds showed no cytotoxic effects.

[0068] After A549 cells were added to the drug and mixed, they were incubated at room temperature for 6 hours and then infected with influenza virus A / FM / 1 / 47. Different concentrations of the drug were added to the treatment groups at the same time. After 24 hours, the viral RNA content was detected by RT-qPCR and the viral protein content was detected by Western blot.

[0069] The results are as follows Figure 12 As shown, in A549 cells, the positive control drug baloxavir (Bal, 20 nM) exhibited significant anti-influenza virus activity, consistent with reported results, demonstrating the reliability of the experimental system. CD-1 and CD-2 dose-dependently reduced the RNA level of influenza virus M2, showing a significant difference compared to the virus control group. Furthermore, CD-1 and CD-2 also dose-dependently inhibited the protein expression of influenza virus PB2. These results indicate that both CD-1 and CD-2 possess significant anti-influenza virus activity.

[0070] (3) Anti-coronavirus (CoV) activity.

[0071] Huh7.5 cells were incubated with different concentrations of CD-1 and CD-2 at room temperature for 48 hours, and then cytotoxicity was detected using a CCK-8 assay kit. The results are as follows: Figure 13 As shown, CD-1 in Huh7.5 cells TC 50 =323.7 μg / mL, TC0=133 μg / mL, TC of CD-2 in Huh7.5 cells 50 =239.6 μg / mL, TC0=133 μg / mL. The maximum concentration used in subsequent pharmacodynamic studies was 50 μg / mL, at which the compound showed no cytotoxic effects.

[0072] Huh7.5 cells were incubated at room temperature for 6 hours after being mixed with different concentrations of CD-1 and CD-2, and then infected with HCoV-229E. The treatment groups were simultaneously treated with different concentrations of CD-1 and CD-2, or with the positive control drug remdesivir (RDV, 1 μM). After 48 hours, total RNA and protein were extracted from the cells. Viral RNA content was detected by RT-qPCR, and viral protein content was detected by Western blot. The results are shown below. Figure 14 As shown, in Huh7.5 cells, the positive control drug remdesivir (RDV, 1 μM) exhibited significant anti-coronavirus activity, consistent with literature reports and laboratory results, demonstrating the reliability of the experimental system. CD-1 and CD-2 dose-dependently reduced the RNA level of HCoV-229E NP, showing a significant difference compared to the virus control group. CD-1 also reduced the EC50 of HCoV-229E RNA. 50 The concentration was 15.26 ± 3.59 μg / mL, and the EC50 of CD-2 against HCoV-229E RNA was [missing value].50 The concentration was 17.62 ± 1.97 μg / mL. Furthermore, CD-1 and CD-2 also inhibited the expression of HCoV-229E NP protein in a dose-dependent manner. These results indicate that both CD-1 and CD-2 have significant anti-coronavirus HCoV-229E activity.

[0073] Therefore, this invention discloses a terminal hydroxyl-thioalkyl α-cyclodextrin sulfate derivative, its synthesis method, and its applications, belonging to the technical field of α-cyclodextrin derivatives. This invention successfully prepared compounds 1-6 and 2-4 by introducing highly hydrophilic groups into the α-cyclodextrin structure. The method is simple, efficient, and the process is controllable, resulting in high purity and easy preparation. The prepared compounds 1-6 and 2-4, by mimicking the HSPG structure, competitively bind to the envelope proteins of RSV, IAV, and CoV viruses. Through the synergistic effect of polyvalent sulfonic acid and alkyl chains, they block virus adsorption and irreversibly destroy the virus structure, achieving a broad-spectrum antiviral effect against respiratory viruses. The synthesis method of terminal hydroxyl-thioalkyl α-cyclodextrin sulfate derivatives established in this invention can prepare target derivatives with different degrees of substitution and exhibit antiviral activity, providing theoretical support for the application of α-cyclodextrin derivatives in the biological and pharmaceutical fields.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A hydroxyl-terminated thioalkyl α-cyclodextrin sulfate derivative, characterized in that: The terminal hydroxyl thioalkyl α-cyclodextrin sulfate derivatives are compounds 1-6 and compounds 2-4; The structural formulas of compounds 1-6 are as follows: ; The structural formula of compounds 2-4 is as follows: .

2. The method for synthesizing a hydroxyl-terminated thioalkyl α-cyclodextrin sulfate derivative as described in claim 1, characterized in that: It is prepared by introducing highly hydrophilic groups into the structure of α-cyclodextrin as the starting material.

3. The method for synthesizing a hydroxyl-terminated thioalkyl α-cyclodextrin sulfate derivative according to claim 2, characterized in that, The steps for preparing compounds 1-6 are as follows: S1. Vacuum-dried α-cyclodextrin, tert-butyldimethylchlorosilane and imidazole were placed in the same container and subjected to anhydrous and oxygen-free operation. Anhydrous dimethylformamide was added under a protective atmosphere. After all components were completely dissolved, the reaction was carried out under a protective atmosphere. The reaction solution was then poured into ice water and filtered. The precipitate was collected, washed with ice water and dried to obtain crude compound 1-1. S2. The crude compound 1-1 prepared in S1 and sodium hydride were subjected to anhydrous and oxygen-free operation. Then, anhydrous dimethylformamide was slowly added and reacted until a grayish-white "cloud"-like substance appeared. Iodomethane was then added dropwise under ice-water bath conditions until the grayish-white "cloud"-like substance disappeared. The reaction was continued and then transferred to room temperature with stirring. After the reaction was completed, the mixture was cooled to 0°C and methanol was added dropwise until no bubbles were produced. After removing the methanol, dichloromethane was added to the reaction system. The mixture was then washed with deionized water, sodium thiosulfate solution, and deionized water in sequence. After separating the organic phase, the mixture was dried, filtered, and purified to obtain compound 1-2. S3. Compound 1-2 obtained in S2, ammonium fluoride, and anhydrous methanol are heated and refluxed until the reaction is complete. After removing the solvent, dichloromethane is added and sonicated. After filtration, solvent removal, and purification, compound 1-3 is obtained. S4. Compounds 1-3 obtained in S3 and sodium hydride were subjected to anhydrous and oxygen-free operation. Then, anhydrous dimethylformamide was added under ice bath conditions. After stirring at 0°C, allyl bromide was added to continue the reaction. Then, the reaction was transferred to room temperature and stirred until the reaction was completed. After cooling to 0°C, methanol was added dropwise until no more bubbles were produced. After removing the methanol, dichloromethane was added to the reaction system. After the reaction, the system was washed with deionized water, sodium thiosulfate solution, and deionized water in sequence. The organic phase was separated and dried, the organic solvent was removed, and the system was purified to obtain compounds 1-4. S5. Compounds 1-4 obtained in S4, 11-mercapto-1-undecanol, and anhydrous methanol were added to the same reaction vessel and stirred until completely dissolved. Then, azobisisobutyronitrile was added, and the mixture was stirred and heated under reflux. Azobisisobutyronitrile was added during the reaction. After the reaction was completed, the solvent was removed, excess 11-mercapto-1-undecanol was recovered, and the mixture was purified and separated to obtain compounds 1-5. S6. Compounds 1-5 obtained in S5 and sulfur trioxide pyridine were placed in the same container and subjected to anhydrous and oxygen-free operation. Then anhydrous tetrahydrofuran was added, and the reaction was carried out under constant temperature and stirring. After removing the solvent, the pH of the solution in the reaction system was adjusted to 9-10. After a pale yellow solid gradually precipitated out, sodium chloride solid was added. After the pale yellow solid was completely precipitated, it was filtered. The pale yellow solid was dissolved in methanol, and the sodium chloride was removed by centrifugation. Then the methanol was removed, and the product was dried to obtain compounds 1-6.

4. The method for synthesizing a hydroxyl-terminated thioalkyl α-cyclodextrin sulfate derivative according to claim 3, characterized in that, In S1, the mass-to-volume ratio of α-cyclodextrin: tert-butyldimethylchlorosilane: imidazole: anhydrous dimethylformamide is 1g:1g:1g:23-24mL; in S2, the mass-to-volume ratio of compound 1-1: sodium hydride: anhydrous dimethylformamide: iodomethane: dichloromethane is 2.5g:3.3g:100mL:3.75mL:60mL; in S3, the mass-to-volume ratio of compound 1-2: ammonium fluoride: anhydrous methanol: dichloromethane is 1g:0.72g:80mL:30mL; The mass-to-volume ratio of compounds 1-3 in S4: sodium hydride: anhydrous dimethylformamide: allyl bromide: dichloromethane is 0.6 g: 0.33 g: 35 mL: 2 mL: 30 mL; the mass-to-volume ratio of compounds 1-4 in S5: 11-mercapto-1-undecanol: anhydrous methanol: azobisisobutyronitrile is 0.2 g: 0.192 g: 35 mL: 0.02 g; the mass-to-volume ratio of compounds 1-5 in S6: sulfur trioxide pyridine: anhydrous tetrahydrofuran is 0.13 g: 0.08 g: 20 mL.

5. The method for synthesizing a hydroxyl-terminated thioalkyl α-cyclodextrin sulfate derivative according to claim 3, characterized in that: In S2 and S4, the system is washed 3-5 times with deionized water and 2-3 times with sodium thiosulfate solution. The amount of deionized water and sodium thiosulfate solution added during washing is 1-2 times the volume of the reaction system. Purification in S2-S5 is performed using silica gel column chromatography.

6. The method for synthesizing a hydroxyl-terminated thioalkyl α-cyclodextrin sulfate derivative according to claim 3, characterized in that: In step S3, the heating conditions are 70-80℃; the ultrasonic treatment is performed at 30-40kHz for 5-15 minutes; in step S4, after adding anhydrous dimethylformamide, the reaction is stirred for 0.5-1.5 hours, and after adding allyl bromide, the reaction is performed for 0.5-1.5 hours; in step S5, after adding azobisisobutyronitrile, it is added every 30 minutes, and the reaction is carried out under reflux at 70-80℃ for 12 hours; after adding anhydrous tetrahydrofuran, the reaction is heated and stirred at 40℃ for 72 hours; in step S6, after adding anhydrous tetrahydrofuran, the reaction is heated and stirred at 35-45℃.

7. The method for synthesizing a terminal hydroxyl thioalkyl α-cyclodextrin sulfate derivative according to claim 2, characterized in that, The steps for preparing compounds 2-4 are as follows: S(1) Place α-cyclodextrin, barium hydroxide octahydrate, and barium oxide in the same reaction vessel, use nitrogen as a protective gas, and then add anhydrous dimethylformamide and allyl bromide to the reaction system. After the system reacts in an ice-water bath, transfer it to room temperature for stirring. Then add ammonia water to the system and stir. After the reaction is complete, add dichloromethane to fully dissolve the product. After washing with deionized water, separate the organic phase, and then dry, filter, and purify it to obtain the crude product of compound 2-1. S(2) The crude compound 2-1 prepared by S(1) and sodium hydride were subjected to anhydrous and oxygen-free operation. Then anhydrous dimethylformamide was added and stirred to react. Then iodomethane was added and stirred to react. After returning to room temperature, stirring was continued until the reaction was completed. Methanol was added under an ice-water bath until no gas was produced. After recovering the solvent, dichloromethane was added to the reaction system. Then the system was washed with deionized water, sodium thiosulfate solution and deionized water in sequence. After separating the organic phase, the system was dried, filtered and purified to obtain compound 2-2. S(3) Add compound 2-2 obtained from S(2), 11-mercapto-1-undecanol, anhydrous methanol, and azobisisobutyronitrile to the same reaction vessel. After all the compounds are dissolved, stir and heat under reflux. During the reaction, azobisisobutyronitrile is added. After the reaction is completed, remove the solvent and purify and separate to obtain compound 2-3. S(4) and the compounds 2-3 and sulfur trioxide pyridine obtained from S(3) were placed in the same container for anhydrous and oxygen-free operation. Then anhydrous tetrahydrofuran was added, and the mixture was heated and stirred under constant temperature until the reaction was completed. The tetrahydrofuran solvent was removed, and the pH of the solution in the reaction system was adjusted to 9-10. After a pale yellow solid gradually precipitated, sodium chloride solid was added. After the pale yellow solid was completely precipitated, it was filtered. The pale yellow solid was dissolved in methanol, and the sodium chloride was removed by centrifugation. Then the methanol was removed, and the mixture was dried to obtain compound 2-4.

8. The method for synthesizing a hydroxyl-terminated thioalkyl α-cyclodextrin sulfate derivative according to claim 7, characterized in that: In S(1), the mass-to-volume ratio of α-cyclodextrin: barium hydroxide octahydrate: barium oxide: anhydrous dimethylformamide: allyl bromide is 1g:5g:5g:30mL:6mL; in S(2), the mass-to-volume ratio of compound 2-1: sodium hydride: anhydrous dimethylformamide: iodomethane: dichloromethane is 1g:0.35g:30mL:2mL:30mL; in S(3), the mass-to-volume ratio of compound 2-2: 11-mercapto-1-undecanol: anhydrous methanol: azobisisobutyronitrile is 0.2g:0.4g:40mL:0.02g; in S(4), the mass-to-volume ratio of compound 2-3: sulfur trioxide pyridine: anhydrous tetrahydrofuran is 0.269g:0.161g:20mL.

9. The method for synthesizing a hydroxyl-terminated thioalkyl α-cyclodextrin sulfate derivative according to claim 7, characterized in that: The ammonia water added in S(1) has a mass fraction of 28%; the amount of deionized water added during washing is 1-2 times the volume of the reaction system; after all the contents of S(3) are dissolved, the mixture is stirred and heated under reflux at 70-80℃, and the reaction is monitored by TLC until it is complete; azobisisobutyronitrile is added every 30 minutes; after anhydrous tetrahydrofuran is added to S(4), the mixture is heated and stirred at 40℃, and the reaction is monitored by TLC until it is complete.

10. The use of the terminal hydroxyl thioalkyl α-cyclodextrin sulfate derivative as described in claim 1 in the preparation of antiviral agents.

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