Antioxidant and anti-inflammatory prodrug as well as preparation and application thereof

Abstract

The invention relates to the technical field of medicines, in particular to an antioxidant and anti-inflammatory prodrug as well as preparation and application thereof. The antioxidant and anti-inflammatory prodrug is gallic acid-dexamethasone ester obtained by connecting gallic acid with antioxidant activity and dexamethasone with anti-inflammatory activity through ester bonds, and the structural formula of the antioxidant and anti-inflammatory prodrug is as shown in formula I; according to the technical scheme disclosed by the invention, not only is a synthesis method of the antioxidant and anti-inflammatory prodrug provided, but also the suspension eye drops prepared from the prodrug show remarkable anti-inflammatory and antioxidant activity, specifically, systemic or local inflammatory diseases can be synergistically treated through the anti-inflammatory effect of dexamethasone and the antioxidant effect of gallic acid; the effects of enhancing the effect and reducing toxicity are achieved, and a new thought is provided for treatment of inflammatory diseases. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to the field of pharmaceutical technology, and particularly to an antioxidant and anti-inflammatory prodrug and its preparation and application. Background Art

[0002] Inflammatory response is a common pathological process in clinic. During the onset of most inflammations, a persistent oxidative stress state will be generated, which will in turn lead to the production of a large number of pro-inflammatory cytokines, exacerbate the inflammatory response, and harm the organs and tissues of various parts of the body. When non-infectious inflammatory diseases occur, such as iritis, keratitis, cyclitis, non-infectious uveitis, hepatitis, meningitis, nephritis, otitis media, and some autoimmune diseases, etc., the severity of the disease is positively correlated with the oxidative stress state of the body. Therefore, designing and developing a co-delivery system for drugs with anti-inflammatory and antioxidant effects can effectively control inflammation by acting together from two aspects of anti-inflammation and reducing oxidative stress of the body.

[0003] Gallic acid (GA), whose chemical name is 3,4,5-trihydroxybenzoic acid, is a phenolic compound naturally present in several plants, such as rowan, Chinese fir, indica rice, guava, zygotes, grapes, Virginia broom, etc. GA is famous for its antioxidant activity. In elastase-induced pulmonary emphysema in rats, GA has been shown to inhibit inflammation and oxidative stress by regulating the Nrf2-HO-1-NF-κB signaling pathway. In addition, GA has been shown to have antioxidant stress and renal protective effects on paraquat-induced kidney injury in male rats. However, due to its polyhydroxy structure, GA has low intestinal permeability and is easily converted by metabolic enzymes in the body. Previous studies have shown that only 0.012% of the initial oral dose of GA can be detected in plasma. The extremely low bioavailability results in the inability to effectively treat inflammatory diseases by single application of GA.

[0004] Dexamethasone (DEX) is a synthetic steroid. Due to its anti-inflammatory, anti-allergic and immunosuppressive properties, it has been widely used to treat various inflammatory diseases. However, high-dose or long-term use of dexamethasone will cause serious side effects, such as hypertension, peptic ulcer, hyperglycemia and water and electrolyte disorders. In order to solve the defects existing in the clinical application of the above two antioxidant and anti-inflammatory drugs, it is necessary to develop a new drug delivery system for co-delivering the two drugs to achieve the purpose of increasing drug efficacy and reducing drug toxicity and side effects. Summary of the Invention

[0005] The present invention provides an antioxidant and anti-inflammatory prodrug and its preparation and application.

[0006] The present invention realizes the above objectives through the following technical solutions:

[0007] An antioxidant and anti-inflammatory prodrug, the antioxidant and anti-inflammatory prodrug is gallic acid with antioxidant activity and dexamethasone with anti-inflammatory activity connected by forming an ester bond to obtain gallic acid-dexamethasone ester, and its structural formula is shown in Formula I:

[0008]

[0009] A preparation method of the antioxidant and anti-inflammatory prodrug is as follows:

[0010]

[0011] Specific synthesis steps:

[0012] A. Protect the phenolic hydroxyl group and carboxyl group of gallic acid with a protecting group, and then add acetic acid-water to remove the protection of the carboxyl group;

[0013] B. Esterify gallic acid protected by a protecting group with dexamethasone in the presence of 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDCI), 4-dimethylamino-pyridine (DMAP) and 1-Hydroxybenzotriazole (HOBT) to generate an intermediate;

[0014] C. The intermediate is deprotected in the presence of Tetrabutylammoniumfluoride (TBAF) / Tetrahydrofuran (THF) to generate the final product gallic acid-dexamethasone ester (DG).

[0015] The protecting group in step A is selected from one of tert-butyldimethylsilyl, tert-butyldiphenylsilyl, and triethylsilyl.

[0016] In step A, the gallic acid solution and the protecting group solution are mixed by stirring at room temperature, and the stirring speed is 500-800 rpm.

[0017] In step B, the mass ratio of gallic acid, EDCI, DMAP, HOBT, and dexamethasone is 4:3-5:1-3:1-3:6.

[0018] The organic solvents in each step can be the same or different and are selected from one or more of N,N-dimethylformamide, ethyl acetate, tetrahydrofuran, and methanol.

[0019] Furthermore,

[0020] S1. Dissolve gallic acid (GA) in an organic solvent to form a gallic acid solution; dissolve tert-butyldimethylchlorosilane in an organic solvent to form a tert-butyldimethylchlorosilane solution, and dissolve tetrabutylammonium fluoride in an organic solvent to form a tetrabutylammonium fluoride solution;

[0021] S2. Mix and stir the gallic acid solution and the tert-butyldimethylchlorosilane solution for 24 h. The mass ratio of the gallic acid solution to the tert-butyldimethylchlorosilane solution is 1:4 - 6. After the reaction, dilute the reaction solution with ethyl acetate and extract with water; dry the organic layer with sodium sulfate and then rotary evaporate to remove the organic solvent to obtain a white solid product A;

[0022] S3. Dissolve the obtained white solid A in an organic solvent, add a mixture of acetic acid - water (3:1 (v / v)), stir and react at room temperature for 24 h. After the reaction, pour the reaction solution into cold water, extract the product with ethyl acetate, and dry the organic matter with Na 2 SO 4 After drying, vacuum concentrate to obtain tert-butyldimethylsilyl-protected gallic acid (TBS-GA);

[0023] S4. Dissolve TBS-GA in an organic solvent, cool to 0 °C, then successively add 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, 4-dimethylaminopyridine, and 1-hydroxybenzotriazole, stir for 2 h to activate the carboxylic acid. After the activation, add dexamethasone and stir and react at room temperature for 24 h. After the reaction, remove the organic solvent to obtain a crude product, and purify it by column chromatography to obtain an intermediate product B;

[0024] S5. Dissolve the intermediate product B in an organic solvent, add the tetrabutylammonium fluoride solution and continue to react for 2 h. After the reaction is completed, dilute the reaction solution with ethyl acetate, wash with saturated brine, and purify by preparative liquid chromatography to obtain the final product DG.

[0025] In the step S2, the mass ratio of the gallic acid solution to the tert-butyldimethylchlorosilane solution and imidazole is 1:4 - 6:3 - 5,

[0026] In the step S3, the volume ratio of the white solid A to the mixture of acetic acid - water is 1:1 - 3.

[0027] The prodrug is first frozen at -80 °C, then freeze-dried using a vacuum freeze dryer, and then stored for a long time under the conditions of light avoidance, nitrogen protection, and -20 °C.

[0028] Use of a said antioxidant and anti-inflammatory prodrug, application of the antioxidant and anti-inflammatory prodrug in the preparation of a drug for preventing or treating non-infectious inflammatory diseases.

[0029] A drug for preventing or treating inflammation, the drug containing the antioxidant anti-inflammatory prodrug described above.

[0030] The dosage form of the drug is a suspension, tablet, capsule, suppository, solution, dripping pill, powder or injection emulsion.

[0031] The inflammation includes but is not limited to non-infectious uveitis, iritis, keratitis, cyclitis, hepatitis, meningitis, nephritis, otitis media and other non-infectious inflammatory diseases.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The present invention adopts a strategy of synergistic anti-inflammatory and antioxidant effects, and uses an esterification reaction to couple dexamethasone and gallic acid to form dexamethasone gallate.

[0034] 2. When the dexamethasone gallate prodrug synthesized by the present invention acts on the inflammatory site, it can release the active ingredients dexamethasone and gallic acid through the cleavage of in vivo esterase. Dexamethasone binds to the glucocorticoid receptor at the inflammatory site to play an anti-inflammatory role, and gallic acid scavenges reactive oxygen species through its antioxidant effect, further reducing the damage of inflammation to the body. The synergistic anti-inflammatory and antioxidant effects can reduce the dosage of glucocorticoid drugs such as dexamethasone in inflammatory diseases and reduce their adverse reactions. The drug safety in use is improved.

[0035] 3. The compound of the present invention links the anti-inflammatory drug dexamethasone and the antioxidant gallic acid through an ester bond, and this compound has both anti-inflammatory and antioxidant dual active pharmaceutical ingredients. At the same time, compared with the corresponding use of gallic acid alone, the lipophilic structure of dexamethasone in the compound can enhance the cell permeability of gallic acid, thereby improving the effectiveness of gallic acid. Compared with the corresponding use of dexamethasone alone, the compound achieves a synergistic anti-inflammatory and antioxidant effect to treat inflammatory diseases, minimizes the dosage of dexamethasone, and further improves the safety of drug application.

[0036] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly and implement it according to the content of the description, the following takes the preferred embodiments of the present invention and combines with the accompanying drawings to describe in detail as follows. Description of the Drawings

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0038] Figure 1 1H NMR spectrum of gallic acid-dexamethasone ester;

[0039] Figure 2 Mass spectrum of gallic acid-dexamethasone ester;

[0040] Figure 3 Transmission electron microscopy image of gallic acid-dexamethasone ester suspension;

[0041] Figure 4 Particle size distribution diagrams of dexamethasone suspension (DEX) and gallic acid-dexamethasone ester suspension (GD);

[0042] Figure 5 In vitro release curves of dexamethasone suspension (DEX) and gallic acid-dexamethasone ester suspension (GD);

[0043] Figure 6 DPPH· free radical scavenging ability test diagram of gallic acid-dexamethasone ester;

[0044] Figure 7 ABTS· free radical scavenging ability test diagram of gallic acid-dexamethasone ester;

[0045] Figure 8 HO· free radical scavenging ability test diagram of gallic acid-dexamethasone ester;

[0046] Figure 9 NO scavenging ability test diagram of gallic acid-dexamethasone ester;

[0047] Figure 10 Anterior segment score diagram (slit lamp microscope) of gallic acid-dexamethasone ester suspension in the treatment of non-infectious uveitis in rats;

[0048] Figure 11 Intraocular pressure changes in each group of rats after treatment with gallic acid-dexamethasone ester suspension eye drops for non-infectious uveitis in rats;

[0049] Figure 12 Anterior segment iris H&E section score diagram of gallic acid-dexamethasone ester suspension eye drops in the treatment of non-infectious uveitis in rats;

[0050] Figure 13 Anterior segment ciliary body H&E section score diagram of gallic acid-dexamethasone ester suspension eye drops in the treatment of non-infectious uveitis in rats;

[0051] Figure 14 Posterior segment optic disc and retina H&E section score diagram of gallic acid-dexamethasone ester suspension eye drops in the treatment of non-infectious uveitis in rats;

[0052] Among them, Figure 10 and Figures 12 - 14 in comparison with the positive group (EAU group), significance is indicated by *, * represents p < 0.05, ** represents p < 0.01, *** represents p < 0.001, and **** represents p < 0.0001. Specific implementation manner

[0053] The following examples are intended to further exemplify the present invention and not limit the present invention in any way.

[0054] Example 1 Synthesis of gallic acid - dexamethasone ester.

[0055] Weigh gallic acid (2 g, 11.76 mmol) and dissolve it in N,N - dimethylformamide to form a gallic acid solution; weigh tert - butyldimethylchlorosilane (TBSCl, 10 g, 66.34 mmol) and dissolve it in N,N - dimethylformamide to form a tert - butyldimethylchlorosilane solution. Mix the gallic acid solution, the tert - butyldimethylchlorosilane solution, and imidazole (IMD, 8 g, 117.51 mmol) and stir for 24 h. After the reaction is completed, dilute the reaction solution with ethyl acetate (160 mL) and extract it with water (6×40 mL); dry the organic layer with sodium sulfate and then rotary evaporate to remove the organic solvent to obtain a white solid product A (6.83 g, yield 93%); dissolve the obtained white solid A in tetrahydrofuran and add a mixture of acetic acid - water (3:1 (v / v)), stir and react at room temperature for 24 h. After the reaction is completed, pour the reaction solution into cold water, extract the product with ethyl acetate, and dry the organic matter with Na 2 SO 4 After drying, vacuum concentrate to obtain tert - butyldimethylsilane - protected gallic acid (TBS - GA) (1.54 g, 94%);

[0056] Weigh TBS - GA (615.5 mg, 1.2 mmol) and dissolve it in dichloromethane, cool to 0 °C, then successively add EDCI (690.12 mg, 3.6 mmol), DMAP (457.67 mg, 3.6 mmol)), and HOBT (486.43 mg, 3.6 mmol), stir for 2 hours to activate the carboxylic acid. After the activation is completed, add dexamethasone (785 mg, 2.0 mmol), stir and react at room temperature for 24 h. After the reaction is completed, remove the organic solvent to obtain a crude product, and purify it by column chromatography to obtain intermediate product B (798.15 mg, 75%);

[0057] Weigh the intermediate B (300 mg, 0.338 mmol), dissolve it in an organic solvent, add tetrabutylammonium fluoride solution and continue the reaction for 2 h. After the reaction is completed, dilute the reaction solution with ethyl acetate and wash it with saturated brine 2 - 4 times. The final product, gallic acid - dexamethasone ester (163.37 mg, 89%), is obtained by preparative liquid chromatography purification. The structure of gallic acid - dexamethasone ester is confirmed by NMR and mass spectrometry, and the results are as Figure 1 and Figure 2 shown.

[0058] Figure 1 Figure is the NMR spectrum of gallic acid - dexamethasone ester. Among them, 7.43 ppm corresponds to H - 1 on the dexamethasone molecule, 7.09 ppm corresponds to H - 3' and H - 7' on the gallic acid molecule, 6.29 ppm corresponds to H - 2 on the dexamethasone molecule, 6.08 ppm corresponds to H - 4 on the dexamethasone molecule, 5.11 ppm corresponds to H - 21 on the dexamethasone molecule, 4.29 ppm corresponds to H - 11 on the dexamethasone molecule, 3.09 - 3.00 ppm corresponds to H - 16 on the dexamethasone molecule, 2.73 ppm corresponds to Ha - 6 on the dexamethasone molecule, 2.48 ppm corresponds to H - 8 on the dexamethasone molecule, 2.40 ppm corresponds to Ha - 12 on the dexamethasone molecule, 2.36 ppm corresponds to Hb - 6 on the dexamethasone molecule, 2.25 ppm corresponds to H - 14 on the dexamethasone molecule, 1.89 ppm corresponds to Ha - 7 on the dexamethasone molecule, 1.77 ppm corresponds to Hb - 12 on the dexamethasone molecule, 1.74 ppm corresponds to Ha - 15 on the dexamethasone molecule, 1.60 ppm corresponds to H - 19 on the dexamethasone molecule, 1.54 ppm corresponds to Hb - 7 on the dexamethasone molecule), 1.21 ppm corresponds to Hb - 15 on the dexamethasone molecule, 1.05 ppm corresponds to H - 18 on the dexamethasone molecule, 0.88 ppm corresponds to H - 22 on the dexamethasone molecule.

[0059] Figure 2 Figure is the mass spectrometry result of gallic acid - dexamethasone ester. The [M + H] peak is at 545.2186, and the [M + Na] peak is at 567.1993, determining the molecular formula as C 29 H 33 FO 9 .

[0060] Example 2 Preparation of Dexamethasone or Gallic Acid - Dexamethasone Ester Suspension

[0061] Table 1: Components and Proportions of Dexamethasone Suspension

[0062] Component Quantity (% w / v) Dexamethasone 1.50 γ - Cyclodextrin 14.00 Disodium Edetate 0.10 Poloxamer 407 2.50 Sodium Chloride 0.57 Sodium Thiosulfate 0.3 Water for Injection Sufficient amount 100.00

[0063] Table 2: Components and Proportions of Gallic Acid-Dexamethasone Ester Suspension

[0064] Component Quantity (% w / v) Gallic Acid - Dexamethasone Ester obtained from the above - mentioned example 1.50 γ - Cyclodextrin 14.00 Disodium Edetate 0.10 Poloxamer 407 2.50 Sodium Chloride 0.57 Sodium Thiosulfate 0.3 Water for Injection Sufficient amount 100.00

[0065] The suspension was prepared as follows:

[0066] Cyclodextrin and poloxamer 407 were added to water to form a suspension. Dexamethasone was added to the suspension and stirred at 95 °C for 15 min until dexamethasone and cyclodextrin were basically dissolved to form a colorless and clear solution. The obtained solution was cooled to 25 °C within 15 min under stirring to obtain a crude suspension containing a solid complex of dexamethasone and cyclodextrin. Finally, a certain amount of 0.5 mm zirconia grinding beads were added. The grinding tube was placed in a grinder and the dexamethasone suspension (DEX) was obtained by adjusting the grinding parameters; at the same time, the gallic acid-dexamethasone ester suspension (GD) was prepared according to the above table and the preparation process;

[0067] The transmission electron microscope photograph of the obtained gallic acid-dexamethasone ester suspension is as Figure 3 shown. The particle size of the suspension was measured by laser diffraction method, and its particle size distribution is as Figure 4 shown. It can be seen from Figure 4 that the particle sizes of DEX and GD are both in the micron range, which indicates that the dispersion states of dexamethasone and gallic acid-dexamethasone ester in water are in suspension form. And after making gallic acid and dexamethasone into a prodrug, the particle size of the prodrug suspension is slightly lower than that of DEX.

[0068] Example 3 In Vitro Release Curves of Dexamethasone or Gallic Acid-Dexamethasone Ester Suspension

[0069] The dynamic dialysis method was used to evaluate the release of gallic acid-dexamethasone ester suspension in artificial tear fluid (ATF). 0.678 g of NaCl, 0.138 g of KCl, 0.0063 g of CaCl 2 and 0.218 g of NaHCO 3 were dissolved in 100 mL of pure water to prepare ATF. 0.5 mL of the gallic acid-dexamethasone ester suspension or dexamethasone suspension prepared in the above example was put into a dialysis bag with a molecular weight of 1 KDa, stirred at 34.5 ± 0.5 °C, and immersed in 375 mL of ATF. Samples (4 ml) were collected at predetermined time points and replaced with fresh ATF at the same temperature. The concentrations of dexamethasone and gallic acid-dexamethasone ester were determined by ultraviolet-visible spectrophotometry, and its in vitro release curve is as Figure 5 shown.

[0070] It can be seen from Figure 5It can be seen that the release rate of gallic acid-dexamethasone ester suspension eye drops is lower than that of dexamethasone suspension eye drops. By 12 hours, the cumulative release amount of dexamethasone reached approximately 90%, while only approximately 60% of gallic acid-dexamethasone ester was released. Gallic acid and dexamethasone in the preparation could be completely released, indicating that the formation of CD aggregates could gradually dissociate into nanoparticles and further release from the inclusion complex. The extended release time reduced the rapid clearance of the drug caused by tear turnover, enabling the drug to be retained on the ocular surface.

[0071] Example 4: Test on the ability of gallic acid-dexamethasone ester suspension to scavenge DPPH free radicals in vitro

[0072] The specific operation for the determination of DPPH free radical scavenging ability was as follows: Methanol solutions of gallic acid-dexamethasone ester at different concentrations (12.5, 25, 50, 100, 200, 400 μg / mL) were mixed with DPPH· free radical solution (2 mM) for 30 minutes. The absorbance was measured at 517 nm, and the percentage inhibition of DPPH· free radicals (I%) was calculated as follows:

[0073] I% = (A blank - A sample ) / A sample × 100%

[0074] where A blank was the absorbance of the control reaction (containing all reagents except the test compound), and A sample was the absorbance of the test compound. The DPPH free radical inhibition rate was as Figure 6 shown.

[0075] From Figure 6 it can be seen that with the increase in the concentration of gallic acid-dexamethasone ester, the corresponding free radicals were rapidly scavenged. Under the treatment of 25 μg / mL DG, the DPPH· free radical scavenging rate reached approximately 80%, showing the highest scavenging ability.

[0076] Example 5: Test on the ability of gallic acid-dexamethasone ester to scavenge ABTS· free radicals in vitro

[0077] The specific operation for the determination of ABTS free radical scavenging ability was as follows: Methanol solutions of different concentrations of dexamethasone gallate were mixed with ABTS· free radical working solution at room temperature for 6 min, the absorbance was measured at 734 nm, and the ABTS· free radical inhibition rate was calculated according to the above formula.

[0078] I% = (A blank - A sample ) / A sample × 100%

[0079] where A blankAbsorbance of the control reaction (containing all reagents except the test compound), A sample Absorbance of the test compound. The ABTS· radical inhibition rate is as Figure 7 shown.

[0080] As Figure 7 can be seen, when the concentration of gallic acid-dexamethasone ester reaches 50 μg / mL, its ABTS· radical scavenging rate can approach 90%. Among a series of polyphenolic compounds, DG exhibits excellent radical scavenging ability.

[0081] Example 6 Test on the ability of gallic acid-dexamethasone ester to scavenge hydroxyl radicals in vitro

[0082] The specific operation for determining the hydroxyl radical scavenging ability was as follows: A mixture of o-phenanthroline methanol solution (o-phenanthroline concentration 0.99 mg / mL, 30 μL), PBS buffer (80 μL), and methanol solutions of dexamethasone gallate at different concentrations (200 μL) was prepared, ferrous sulfate and 0.1% hydrogen peroxide solution were added, incubated at 37 °C for 30 min, the absorbance was measured at 510 nm, and the hydroxyl radical inhibition rate was calculated:

[0083] I% = (A o + A j - A i ) / A 0 × 100%

[0084] Where A 0 is the absorbance of the negative control reaction (containing methanol solution, without the test compound), A j is the absorbance of the positive control reaction (containing aqueous vitamin C solution, without the test compound), and A i is the absorbance of the test compound. The hydroxyl radical inhibition rate is as Figure 8 shown.

[0085] As Figure 8 can be seen, when the concentration of gallic acid-dexamethasone ester reaches 100 μg / mL, the scavenging rate of ·OH radicals approaches 40%, but when the concentration reaches 400 μg / mL, the scavenging rate of ·OH radicals approaches 80%. The above phenomena indicate that gallic acid-dexamethasone ester has excellent scavenging ability for ·OH radicals, and based on the strong scavenging ability for the three radicals, it can be speculated that gallic acid-dexamethasone ester has strong antioxidant ability.

[0086] Example 7 Test on the ability of gallic acid-dexamethasone ester to scavenge NO in vitro

[0087] The specific operation for NO scavenging ability determination is as follows: Mix gallic acid-dexamethasone ester methanol solutions with different concentrations with sodium nitroprusside (7.5 mM) (volume ratio 9:1), and incubate at 25 °C for 2 h. The NO scavenging ability is determined at 540 nm using Griess reagent. The NO scavenging rate is calculated as follows:

[0088] NO clearance rate(%)=(1-A sample / A blank )×100%

[0089] Where A blank is the absorbance of the control reaction (containing all reagents except the test compound), and A sample is the absorbance of the test compound. The NO inhibition rate is as Figure 9 shown.

[0090] As Figure 9 can be seen, when the concentration of gallic acid-dexamethasone ester is 100 μg / ml, the NO scavenging rate exceeds 30%. NO is one of the reactive nitrogen species (RNS), so the reactive oxygen species (ROS) and RNS generated by oxidative stress are considered to be the initial pathological events leading to the uveitis-induced damage observed in the amplification stage. Studies have shown that reducing NO can effectively alleviate uveitis inflammation in rats. Gallic acid-dexamethasone ester not only has anti-inflammatory ability but also has antioxidant properties. It can reduce ROS by eliminating free radicals and NO, which may be more effective in treating uveitis.

[0091] Example 8 Pharmacodynamic verification of gallic acid-dexamethasone ester suspension in the treatment of non-infectious uveitis in rats

[0092] An experimental autoimmune uveitis (EAU) model was established in female Lewis rats (6 - 8 weeks old, 160 - 180 g). Bovine IRBP R16 was emulsified with complete Freund's adjuvant (CFA) containing 2 mg / mL Mycobacterium tuberculosis H37RA strain. On day 0, 125 μL of the antigen emulsion was subcutaneously injected into the bilateral hind footpads of the rats. On day 6 after immunization, the rats were randomly divided into 5 groups (n = 3 rats per group): (1) Normal group: non - immunized group, no drug administration; (2) EAU group: immunized rats without treatment; (3) DEX group: rats were given dexamethasone suspension eye drops (15 mg / mL, 10 μL / eye, the composition and preparation method are as in Example 2), 3 times a day; (4) Low dosage group of gallic acid - dexamethasone ester: given gallic acid - dexamethasone ester suspension eye drops (10 mg / mL, 10 μL / eye, the composition and preparation method are as in Example 2), 3 times a day; (5) High dosage group of gallic acid - dexamethasone ester: given gallic acid - dexamethasone ester suspension eye drops (10 mg / mL, 10 μL / eye, the composition and preparation method are as in Example 2), 6 times a day. The clinical symptoms of ocular inflammation were examined and scored every 2 days using a slit - lamp biomicroscope. The results are as Figure 10 shown. To exclude any side effects of dexamethasone eye drops, the changes in intraocular pressure (IOP) of each group were monitored. The results are as Figure 11 shown.

[0093] It can be concluded from Figure 10 that on day 14 after immunization, obvious clinical symptoms of uveitis (i.e., pupil occlusion, ptosis) appeared in the EAU group, while almost no inflammatory reaction was seen in the drug - administered groups.

[0094] It can be concluded from Figure 11 that after drug administration, the IOP in the dexamethasone group increased significantly; in contrast, the IOP in the low - dosage and high - dosage groups of gallic acid - dexamethasone ester decreased more. These results indicate that the gallic acid - dexamethasone ester suspension can reduce the adverse reactions caused by dexamethasone and has a positive therapeutic effect on rat non - infectious uveitis.

[0095] Example 9 Slice scoring of dexamethasone gallate suspension in the anterior and posterior segments of the eyes of rats with non - infectious uveitis

[0096] On the 14th day after immunization, the rats in each group were sacrificed, and their eyeballs were taken for histopathological analysis. After dehydration, the fixed samples were embedded in paraffin and sectioned into thin slices 5 μm thick, and stained with hematoxylin and eosin (H&E). Pathologists evaluated the inflammatory response and retinal damage. On the 14th day after immunization, histopathological sections of the iris, ciliary body and retina of each group were made and scored. The results of the H&E section scores of the anterior and posterior segments of the eyes of rats treated with dexamethasone gallate suspension for non-infectious uveitis are as Figures 12 - 14 shown.

[0097] As can be seen from Figure 12 and 13 , for the anterior segment of the rat eye, a large number of inflammatory cells infiltrated the iris and ciliary body in the EAU group, while the influx of inflammatory cells was significantly reduced in the DEX, low-dose and high-dose groups. As can be seen from Figure 14 , in the posterior segment of the rat eye, a large amount of inflammatory exudates accumulated in the retina and optic disc in the EAU group, accompanied by severe damage to the retinal structure (i.e., retinal folds). The dexamethasone group, the low-dose group of gallic acid-dexamethasone ester and the high-dose group of gallic acid-dexamethasone ester could all reduce the inflammatory response in the retina and optic disc.

Claims

1. An antioxidant and anti-inflammatory prodrug, characterized in that: The antioxidant and anti-inflammatory prodrug is gallic acid with antioxidant activity and dexamethasone with anti-inflammatory activity connected by ester bond to obtain gallic acid-dexamethasone ester, and its structural formula is shown in Formula I:

2. A method for preparing the antioxidant and anti-inflammatory prodrug according to claim 1, characterized in that: The synthetic route is as follows:

3. The method for preparing the antioxidant and anti-inflammatory prodrug according to claim 2, characterized in that: The synthesis steps include: A. Protect the phenolic hydroxyl group and carboxyl group of gallic acid with a protecting group, and then add acetic acid-water to remove the protection of the carboxyl group; B. Gallic acid protected by a protecting group is esterified with dexamethasone in the presence of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDCI), 4-dimethylamino-pyridine (DMAP) and 1-hydroxybenzotriazole (HOBT) to generate an intermediate; C. The intermediate is freed from the protecting group in the presence of tetrabutylammonium fluoride (TBAF) / tetrahydrofuran (THF) to generate the final product gallic acid-dexamethasone ester.

4. The method for preparing the antioxidant and anti-inflammatory prodrug according to claim 3, characterized in that: The protecting group in step A is selected from one of tert-butyldimethylsilyl, tert-butyldiphenylsilyl and triethylsilyl.

5. The method for preparing the antioxidant and anti-inflammatory prodrug according to claim 3, characterized in that: In the step A, the gallic acid solution and the protecting group solution are mixed by stirring at room temperature at a stirring speed of 500-800 rpm.

6. The method for preparing the antioxidant and anti-inflammatory prodrug according to claim 3, characterized in that: In the step B, the mass ratio of gallic acid, EDCI, DMAP, HOBT and dexamethasone is 4:3-5:1-3:1-3:

6.

7. The method for preparing the antioxidant and anti-inflammatory prodrug according to claim 3, characterized in that: The organic solvents in each step may be the same or different and may be selected from one or more of N,N-dimethylformamide, ethyl acetate, tetrahydrofuran and methanol.

8. A use of the antioxidant and anti-inflammatory prodrug according to claim 1, characterized in that: The antioxidant and anti-inflammatory prodrug is used in preparing a drug for preventing or treating non-infectious inflammatory diseases.

9. A drug for preventing or treating inflammation, characterized in that: The medicine contains the antioxidant and anti-inflammatory prodrug according to claim 1.

10. The anti-inflammatory drug according to claim 9, characterized in that: The dosage form of the drug is suspension, tablet, capsule, suppository, solution, drop pill, powder or injection emulsion.

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