Ionic liquid for treating xerophthalmia and application thereof

Abstract

The invention discloses ionic liquid for treating xerophthalmia, and belongs to the field of biological medicine. The ionic liquid is synthesized from L-carnitine and taurine through an ion exchange reaction, has excellent membrane permeability and stability, acts on ocular surface lesions, and can recover tear secretion, improve lipid metabolism disorder, inhibit inflammatory response and promote cornea repair. Animal test results show that the ionic liquid remarkably increases the tear secretion amount of a dry eye model rat and repairs cornea and conjunctiva tissue damage, and the curative effect of the ionic liquid is superior to that of single use of L-carnitine or taurine. The preparation process is simple, and is suitable for developing the eye drops for accurately and efficiently treating xerophthalmia.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomedicine, and in particular relates to an ionic liquid and an application thereof in treating dry eye. Background Art

[0002] Dry eye disease is a widespread and disabling eye disease affecting hundreds of millions of people worldwide. Characterized by tear film instability, chronic inflammation, and neurosensory dysfunction, it ultimately leads to ocular surface damage, corneal epithelial destruction, and progressive vision loss. In addition to physical symptoms such as dryness, irritation, and pain, dry eye significantly reduces patients' quality of life and imposes a heavy socioeconomic burden. Evaporative dry eye accounts for 60%-70% of all cases, with its core pathological mechanism stemming from abnormalities in the tear film lipid layer caused by meibomian gland dysfunction. Due to insufficient lipid secretion or altered lipid composition, these patients are unable to effectively inhibit tear evaporation (the evaporation rate increases 2-3 times compared to normal). Simultaneously, levels of inflammatory factors at the eyelid margin increase, creating a vicious cycle of lipid metabolism disturbances and an inflammatory microenvironment.

[0003] The pathogenesis of dry eye disease is multifactorial and complex, influenced by environmental stressors (such as prolonged screen use and air pollution), physiological aging, and systemic medication. These factors disrupt tear film homeostasis, trigger an inflammatory cascade, interfere with lipid metabolism, and induce cellular stress, particularly in the ocular epithelial cells. Existing treatments (including artificial tears, corticosteroids, and immunosuppressants such as cyclosporine) can temporarily relieve symptoms but often lack lasting efficacy. These therapies are limited by poor ocular retention, insufficient tissue penetration, and frequent adverse reactions. Specifically, conventional eye drops have a bioavailability of less than 5% and a corneal contact time of less than 2 minutes. Systemic administration suffers from low blood-ocular barrier penetration (less than 0.1%), highlighting the urgent need to develop innovative treatment strategies targeting the cellular and molecular mechanisms of the disease.

[0004] Ionic liquids (ILs), liquid salts composed of specific anions and cations, are widely used in various fields, including as solvents, catalysts, and electrolytes in batteries and fuel cells. In recent years, the application of ILs has expanded to materials engineering and biomedicine. Their amphiphilic structure endows them with excellent membrane permeability and enhanced stability, while their inherent bioactivity enables them to selectively interact with cellular components. In particular, the ability of ILs to penetrate biological barriers gives them unique advantages in ocular drug delivery. Ionic liquids also exhibit significant bioactivity, including antibacterial and anticancer activities, further highlighting their potential for application in multiple therapeutic areas, including ophthalmology. Summary of the Invention

[0005] The purpose of the present invention is to provide an ionic liquid for local targeted, precise and efficient treatment of dry eye.

[0006] To achieve the above objectives, the present invention uses the following technical means: An ionic liquid for treating dry eye is synthesized by an ion exchange reaction using L-carnitine as a cation and taurine as an anion, wherein the molar ratio of L-carnitine to taurine is 1:1.

[0007] The preparation method comprises the following steps: a) dissolving L-carnitine and taurine in deionized water to obtain a L-carnitine solution and a taurine solution, respectively; b) mixing the L-carnitine solution and the taurine solution, stirring at 20-30°C and 500-800 rpm for 10-20 hours; c) After the reaction is completed, water is removed by reduced pressure distillation and vacuum drying to obtain the ionic liquid.

[0008] Experiments have shown that the ionic liquid can penetrate the ocular surface barrier, significantly increase tear secretion, reduce corneal staining scores, and repair corneal epithelium and conjunctival goblet cells. Therefore, it can be used in the clinical treatment of dry eye, especially evaporative dry eye, with long-lasting efficacy and no significant adverse reactions.

[0009] The present invention further provides an eye drop for treating dry eye, comprising the ionic liquid. The eye drop may further comprise a solvent, an osmotic pressure regulator, a preservative, a thickener, a stabilizer, and other carriers or excipients commonly used in eye drops.

[0010] The beneficial effects of the present invention are: L-carnitine is an amino acid derivative that is usually involved in the metabolism of fatty acids in the body. L-carnitine has antioxidant and anti-inflammatory effects and protects ocular surface cells. Taurine is an amino acid containing a sulfonic acid group. It exists naturally in the eye, especially in the retina. It helps maintain normal eye function and also has antioxidant and osmotic pressure regulating effects.

[0011] This invention combines two natural products synthesized by the human body through ion exchange to form a stable ionic liquid [Car][Tau]ILs. These ILs possess excellent membrane permeability and stability, penetrating the barrier to reach the affected area, restoring tear secretion, improving ocular surface lipid metabolism disorders, inhibiting inflammation, and promoting corneal repair, thereby achieving the purpose of treating dry eye. The invention also offers advantages such as rapid onset of action, long-lasting efficacy, and high safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 : Schematic diagram of the reaction of taurine and L-carnitine to produce [Car][Tau]ILs.

[0013] Figure 2 : Infrared spectrum of [Car][Tau]ILs.

[0014] Figure 3 :H NMR spectrum of [Car][Tau]ILs.

[0015] Figure 4 :H NMR spectrum and C NMR spectrum of [Car][Tau]ILs.

[0016] Figure 5 : Changes in tear secretion during treatment in dry eye rats.

[0017] Figure 6 : Changes of sodium fluorescein staining and sodium fluorescein staining scores in dry eye rats during treatment.

[0018] Figure 7 : HE staining and corneal thickness statistics of rat corneas in different treatment groups.

[0019] Figure 8 : PAS staining and goblet cell counts in the conjunctiva of rats in different treatment groups. DETAILED DESCRIPTION

[0020] The present invention will be described in further detail below in conjunction with specific examples. It should be noted that the specific examples are intended only to explain the present invention and are not intended to limit the present invention. In addition, the various experimental operations involved in the examples are conventional operations in the art unless otherwise stated. For parts not specifically described herein, those of ordinary skill in the art can refer to various commonly used reference books, scientific and technological literature, or relevant specifications, manuals, etc. before the filing date of the present invention for implementation.

[0021] Example 1 Preparation and characterization of drugs Preparation of ionic liquid [Car][Tau]ILs: Take 500mg of taurine and dissolve it in 10mL of deionized water; take 644mg of L-carnitine and dissolve it in 10mL of deionized water, add the L-carnitine solution dropwise to the taurine solution, and stir at 500rpm at 25℃ for 12 hours. After the reaction is completed, most of the water is removed by vacuum distillation at 60℃, and then placed in a vacuum drying oven at 60℃ for further drying for 24 hours to obtain the final product [Car][Tau]Ils. The preparation principle and reaction process are as follows Figure 1 As shown, L-carnitine is used as a cation and taurine is used as an anion, and the two are used to prepare an ionic liquid through an ion exchange reaction. It can be seen that [Car][Tau]ILs is a colorless and transparent liquid with a certain fluidity.

[0022] The prepared [Car][Tau]ILs were characterized and detected by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy.

[0023] Experimental results: From Figure 2 The infrared spectrum of the ionic liquid salt can be seen in the figure, where 1710 cm -1 The characteristic absorption peak at 1215 cm corresponds to the carboxyl group (-COOH) of L-carnitine in [Car][Tau]ILs; -1 and 1616cm -1 The characteristic absorption peaks at correspond to the sulfonic acid group (-SO3) and amino group (-NH2) of taurine in [Car][Tau]ILs. Figure 3 From the 1H NMR spectrum of [Car][Tau]ILs shown, it can be seen that the signal peaks of methylene in L-carnitine are at 2.33ppm, 3.12ppm and 3.33ppm, the signal peak of -CHOH- in L-carnitine is at 4.46ppm, the signal peak of methylene in taurine is at 3.18ppm and 3.34ppm, and the chemical shifts of 3.35ppm (SO3CH2-) and 3.13ppm (-CH2NH2) in [Car][Tau]ILs have changed, indicating that the carboxyl group in L-carnitine and the sulfonic acid group of taurine undergo a hydrogen ion replacement reaction to generate [Car][Tau]ILs. Figure 4 The 13C NMR spectrum of [Car][Tau]ILs shown in the figure shows a carbonyl group at 177.97 ppm; four methylene groups at 70.10 ppm, 47.45 ppm, 42.94 ppm, and 35.32 ppm; three methyl groups at 54.08 ppm, 54.04 ppm, and 54.01 ppm; and a hydroxymethyl group at 64.04 ppm. These results also indicate that [Car][Tau]ILs were successfully prepared.

[0024] Example 2 Evaluation of drug efficacy To establish a rat model of evaporative dry eye, 25 μL of 80% benzalkonium chloride was added to PBS and diluted to 10 mL to obtain a 0.2% benzalkonium chloride solution. Before use, the solution was filtered through a 0.22 μm filter to remove any bacteria and debris. The rats were manually grasped, the periocular skin stretched, and the eyeballs exposed. The 0.2% benzalkonium chloride solution was then instilled onto the ocular surface, 10 μL per eye, three times daily for 14 consecutive days. After model establishment, tear secretion and sodium fluorescein staining were performed to determine model success.

[0025] Sixteen Sprague-Dawley rats with successfully established PD-L1 models were randomly divided into four groups: the Saline group, the Tau group, the Car group, and the [Car][Tau]ILs group. Four normal Sprague-Dawley rats, untreated, were selected and designated the Normal group. The Saline group received saline, the Tau group received taurine, the Car group received L-carnitine, and the [Car][Tau]ILs group received [Car][Tau]ILs. All groups received 10 μL of eye drops (containing 0.01 mg of drug) three times daily for 14 consecutive days. Tear secretion and corneal fluorescein sodium staining of the rats in these five groups were measured on the day before treatment (0 day), the fifth day of treatment (5 day), the tenth day of treatment (10 day), and the fourteenth day of treatment (14 day). (The scoring criteria refer to the literature: Wu Lifeng et al., Research Progress on Animal Models and Drug Efficacy Evaluation of Dry Eye Disease [J]. Zhongnan Pharmacy, 2018, 16(10):1355-1359.) After the 14-day treatment, the cornea and conjunctiva were obtained for corneal HE staining and conjunctival PAS staining, respectively.

[0026] Experimental results: From Figure 5 As can be seen, on day 0, all rats in the control group, except the normal group, successfully established the model. Over time, tear secretion in the Saline group remained almost unchanged, while tear secretion in the other treatment groups increased. Tear secretion in the [Car][Tau]ILs group was significantly higher than in the other groups. These results suggest that treatment with [Car][Tau]ILs can significantly increase tear secretion and improve the clinical symptoms of evaporative dry eye.

[0027] from Figure 6 Representative images of sodium fluorescein staining (left) and sodium fluorescein staining scores (right) show that from day 0 to day 14, the corneal epithelium of the Normal group showed no obvious staining, while the corneas of the other groups on day 0 showed large areas of sodium fluorescein staining, indicating that the model was successful. As time went by, the staining decreased and the scores decreased. However, the corneal sodium fluorescein staining of the [Car][Tau]ILs group was significantly reduced, the corneal epithelium was smoother, and the staining score was significantly different from that of the other groups, indicating that [Car][Tau]ILs can effectively repair corneal damage caused by dry eye.

[0028] from Figure 7The results of corneal HE staining showed that the cornea of ​​the Normal group was neatly and densely arranged, while the number of corneal epithelial cells in the Saline group was reduced and the morphology was irregular, and its thickness was greatly reduced. After treatment with L-carnitine (Car) and taurine (Tau), the corneal morphology was improved but the effect was limited. After treatment with [Car][Tau]ILs, the corneal morphology and structure were restored to a large extent.

[0029] from Figure 8 The PAS staining results of the conjunctiva showed that there were a large number of goblet cells in the normal fornix conjunctiva of the Normal group, while the goblet cells in the Saline group were significantly lost and atrophied. The number of goblet cells in the [Car][Tau]ILs group increased significantly, and their morphology was restored, approaching a healthy state.

Claims

1. An ionic liquid for treating dry eye, characterized in that: The ionic liquid is synthesized by using L-carnitine as a cation and taurine as an anion through an ion exchange reaction, and the molar ratio of the L-carnitine to the taurine is 1:

1.

2. A method for preparing the ionic liquid according to claim 1, characterized in that The following steps are involved: a) dissolving L-carnitine and taurine in deionized water to obtain a L-carnitine solution and a taurine solution, respectively; b) mixing the L-carnitine solution and the taurine solution, stirring at 20-30°C and 500-800 rpm for 10-20 hours; c) After the reaction is completed, water is removed by reduced pressure distillation and vacuum drying to obtain the ionic liquid.

3. Use of the ionic liquid according to claim 1 in the preparation of a drug for treating dry eye.

4. The use according to claim 3, characterized in that: The dry eye is evaporative dry eye.

5. An eye drop for treating dry eye, characterized in that: The invention comprises the ionic liquid according to claim 1.

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