A trpm8 agonist compound and preparation method and use thereof

Abstract

The application belongs to the technical field of medicine preparation, and particularly relates to a TRPM8 agonist compound and a preparation method and application thereof. The deuterated TRPM8 agonist compound provided by the application has excellent TRPM8 receptor agonist activity, can effectively improve the symptoms of dry eye, significantly promote tear secretion and repair corneal epithelial damage, and has better curative effect than existing classical TRPM8 agonists, and can be used for preparing a medicine for treating dry eye, thereby providing a new effective selection for clinical treatment of dry eye. The deuterated TRPM8 agonist compound provided by the application is prepared by using a four-step synthesis process, raw materials are easy to obtain, process operation is simple, and the reaction process is stable and controllable, and is suitable for industrialized synthesis.

Description

Technical Field

[0001] This invention belongs to the field of pharmaceutical preparation technology, specifically relating to a TRPM8 agonist compound, its preparation method, and its uses. Background Technology

[0002] Dry eye syndrome (DED) is a common ocular surface disease with a high incidence rate worldwide. Its prevalence is on the rise due to factors such as excessive use of video terminals and sleep disorders.

[0003] Dry eye syndrome is a complex ocular surface disease mediated by multiple factors. Its core pathological mechanism lies in insufficient tear secretion or excessively rapid tear evaporation, leading to an imbalance in the quality and quantity of natural tears. This results in an inability to maintain normal lubrication and protection of the ocular surface, often accompanied by ocular surface inflammation, abnormal nerve sensitivity, and a series of clinical manifestations such as eye discomfort. Current mainstream treatments for dry eye syndrome have significant limitations: most medications primarily focus on anti-inflammation, lubrication, or artificial tears, generally exhibiting slow onset of action and limited symptom relief. Furthermore, some medications are used frequently and have significant local irritation, easily leading to poor patient satisfaction and long-term medication adherence, failing to meet the clinical demand for rapid, effective, and comfortable treatment for dry eye syndrome. Therefore, developing therapeutic drugs with novel mechanisms of action and superior efficacy is of significant clinical importance.

[0004] In 2025, the U.S. FDA approved Acoltremon (WS-12) eye drops for the treatment of dry eye syndrome. As a first-in-class transient receptor potential M8 (TRPM8) receptor agonist (neuromotor), this drug can rapidly promote physiological tear secretion by stimulating corneal sensory nerves, providing a new treatment option for patients with dry eye syndrome.

[0005] Acoltremon structure.

[0006] Deuterium, as an isotope of hydrogen, has a shape and volume similar to hydrogen in drug molecules, thus deuterated drugs can generally retain the original drug's biological activity and selectivity. Since the carbon-deuterium (CD) bond is more stable than the carbon-hydrogen (CH) bond, it is less likely to break during chemical reactions, theoretically potentially extending the drug's half-life and optimizing its pharmacokinetic properties. However, compared to corresponding non-deuterated drugs, the pharmacokinetic properties of deuterated drugs exhibit significant randomness and unpredictability. Related studies (Scott L. Harbeson, Roger D. Tung, Deuterium in Drug Discovery and Development, pp. 405-406) show that deuteration modification at certain sites not only fails to extend the drug's half-life but may even shorten it, thereby deteriorating its pharmacokinetic characteristics. Furthermore, the hydrogen atoms at some sites in the drug molecule are difficult to deuterate due to steric hindrance and other factors, making drug deuteration design difficult to execute arbitrarily, and predictable modifiable sites in advance.

[0007] Based on this, deuteration modification of existing TRPM8 agonists to develop compounds with better efficacy and more stable pharmacokinetic properties presents both uncontrollable technical challenges and has significant practical and clinical value in providing better treatment options for dry eye patients. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a TRPM8 agonist compound, its preparation method, and its uses. The objective of this invention is to provide a superior TRPM8 agonist compound for the treatment of dry eye syndrome.

[0009] This invention provides a TRPM8 agonist compound or a pharmaceutically acceptable salt thereof, the compound having the following structural formula:

[0010] This invention provides a TRPM8 agonist compound or a pharmaceutically acceptable salt thereof, the compound having the following structural formula:

[0011] This invention provides a TRPM8 agonist compound or a pharmaceutically acceptable salt thereof, the compound having the following structural formula:

[0012] Furthermore, in the above-mentioned TRPM8 agonist compound or its pharmaceutically acceptable salt, the pharmaceutically acceptable salt is any one or more of the following compounds: phosphate, camphor sulfonate, hydrochloride, hydrobromide, hydrofluoric acid, sulfate, nitrate, formate, acetate, propionate, oxalate, malonate, succinate, fumarate, maleate, lactate, malate, tartrate, citrate, picrate, methanesulfonate, trifluoromethanesulfonate, benzylsulfonate, and benzylsulfonate.

[0013] The present invention further provides the use of the above-mentioned TRPM8 agonist compound or a pharmaceutically acceptable salt thereof in the preparation of a medicament for treating dry eye syndrome.

[0014] This invention further provides a method for preparing the above-mentioned TRPM8 agonist compound, comprising the following steps: Step 1: Synthesize compound AM2 from compound AM1 using the method shown in the formula below; Step 2: Synthesize compound AM3 from compound AM2 using the path shown in the formula below; Step 3: Synthesize compound B2 from compound B1 using the method shown in the formula below; Step 4: Synthesize compound AM4 from compound B2 and compound AM3 according to the path shown in the formula below;

[0015] As a further optimization of the preparation method of the above-mentioned TRPM8 agonist compound, in step 1, N-(4-hydroxyphenyl)acetamide AM1 is used as a raw material and undergoes a substitution reaction with deuterated iodomethane in the presence of an alkaline reagent and an organic solvent. The reaction solution is then extracted, dried, and purified to obtain compound AM2.

[0016] As a further optimization of the preparation method of the above-mentioned TRPM8 agonist compound, in step 2, compound AM2 is heated and hydrolyzed under acidic conditions. After the reaction is complete, the system is adjusted to strong alkalinity, and compound AM3 is obtained by extraction, drying and purification.

[0017] As a further optimization of the preparation method of the above-mentioned TRPM8 agonist compound, in step 3, under the protection of an inert gas, compound B1 reacts with oxalyl chloride in an organic solvent at low temperature via DMF catalysis, and after removing the solvent, compound B2 is obtained.

[0018] As a further optimization of the preparation method of the above-mentioned TRPM8 agonist compound, in step 4, under the protection of an inert gas, compound AM3 and compound B2 undergo a condensation reaction in an alkaline reagent, at low temperature, and in an organic solvent. The reaction solution is then post-treated and purified to obtain compound AM4.

[0019] Beneficial effects The TRPM8 agonist compound provided by this invention possesses excellent TRPM8 receptor agonist activity, demonstrating promising application potential in the treatment of dry eye syndrome. It effectively improves dry eye-related symptoms, significantly enhances tear secretion function, and reduces corneal epithelial damage, exhibiting superior effects compared to existing classic TRPM8 receptor agonists. This provides a new and effective option for the clinical treatment of dry eye syndrome. Furthermore, the preparation method of this compound is rational, simple, and uses readily available raw materials. The preparation process is stable and controllable, enabling the efficient preparation of high-purity target compounds that meet the needs of industrial production. This provides a feasible technical path for the large-scale production and practical application of this compound. Attached Figure Description

[0020] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of compound AM2.

[0021] Figure 2 This is the carbon NMR spectrum of compound AM2.

[0022] Figure 3 This is the hydrogen nuclear magnetic resonance spectrum of compound AM3.

[0023] Figure 4 This is the carbon NMR spectrum of compound AM3.

[0024] Figure 5 This is the hydrogen nuclear magnetic resonance spectrum of compound AM4.

[0025] Figure 6 This is the carbon NMR spectrum of compound AM4.

[0026] Figure 7 The image shows the pharmacodynamic test results for dry eye in mice. Figure 7 A shows a comparison of tear length in each group of mice. Figure 7 B is a comparison chart of the sodium fluorescein staining scores of mice in each group. Figure 7 C shows the corneal fluorescein staining images of mice in each group. Detailed Implementation

[0027] The present invention is further illustrated below with specific embodiments. These embodiments are exemplary and intended to illustrate the problems and explain the present invention, and are not intended to be limiting. The raw materials and instruments used in the embodiments are all known products, obtained by purchasing commercially available products.

[0028] I. Synthesis of Compound AM4 (1) Compound AM2 is synthesized from compound AM1 by following the path shown in the formula below.

[0029] To a mixture containing N-(4-hydroxyphenyl)acetamide AM1 (0.5 g, 3.31 mmol), potassium carbonate (0.79 g, 4.96 mmol), and dry acetonitrile (5 mL), deuterated iodomethane (0.35 mL, 5.63 mmol) was slowly added dropwise. The mixture was stirred at room temperature for 24 hours. After the reaction was complete, ethyl acetate (10 mL) and water (10 mL) were added for dilution. The aqueous phase was extracted again with ethyl acetate, and the organic phases were combined and washed with 10% potassium carbonate solution (20 mL). The organic layer was dried over anhydrous sodium sulfate, and the residue obtained by concentration under reduced pressure was slurried with petroleum ether (5 mL) to precipitate a solid. The solid was filtered, washed with petroleum ether, and dried under vacuum to obtain an off-white solid. The solid was purified by silica gel column chromatography with PE-EtOAc (1:1, v / v) to obtain AM2 (0.52 g, 93% yield). 1 HNMR (600 MHz, DMSO-d6): δ H 9.77 (s, 1H), 7.48 (d, J = 12 Hz, 2H), 6.85 (d, J = 12Hz, 2H), 2.01 (s, 3H); 13 C NMR (151 MHz, DMSO-d6) δ C 168.2, 155.5, 133.0, 121.0 (2 x C), 114.2 (2 x C), 54.9, 24.2.

[0030] (2) Compound AM3 is synthesized from compound AM2 by following the path shown in the formula below.

[0031] A mixture of AM2 (0.34 g, 2 mmol), 12 M hydrochloric acid (3 mL), and pure water (1 mL) was heated at 90–95°C for 2 hours. The reaction was not complete, so the reaction was continued for another 24 hours. LC-MS confirmed the reaction was complete. After cooling to room temperature, the pH was adjusted to 14 with sodium hydroxide (10% solution). The aqueous phase was extracted twice with dichloromethane, and the organic phases were combined and dried over anhydrous sodium sulfate. After concentrating the solvent under reduced pressure, a dark orange solid was obtained. Purification by silica gel column chromatography yielded AM3 (0.22 g, 87% yield). 1 H NMR (600 MHz, DMSO-d6): δ H6.63 (d, J = 12 Hz, 2H), 6.51 (d, J = 12 Hz, 2H), 4.56 (active hydrogen); 13 C NMR (151 MHz, DMSO-d6) δ C 150.5, 142.2, 114.8 (2 x C), 114.3 (2 x C), 54.3, LC-MS m / z 127.15 [M + H] + .

[0032] (3) Compound B2 is synthesized from compound B1 by following the path shown in the formula below.

[0033] Under nitrogen protection, compound B1 (0.45 g, 2.44 mmol) was dissolved in anhydrous dichloromethane (15 mL). After cooling to 0 °C, oxaloyl chloride (0.25 mL, 2.93 mmol) was slowly added dropwise. After the addition was complete, 3 drops of DMF were added as a catalyst, and gas was observed to be emitted. After reacting for 4 hours, the solvent was removed by vacuum distillation, and the mixture was dried using an oil pump to obtain compound B2, which was then directly proceeded to the next step.

[0034] (4) Compound AM4 is synthesized from compound B2 and compound AM3 by following the path shown in the formula below.

[0035] Under nitrogen protection, AM3 (100 mg, 0.8 mmol) was dissolved in anhydrous dichloromethane (5 mL), and pyridine (0.13 mL, 1.60 mmol) was added. The solution was cooled to 0 °C, and solution B2 dissolved in dichloromethane (4 mL) was slowly added. The reaction mixture was stirred overnight at room temperature. The filtrate was adjusted to pH 14 with 10% sodium hydroxide solution and then extracted with dichloromethane. The combined organic phases were dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure to give a yellow solid. This solid was purified by silica gel column chromatography (DCM as eluent) to give a white solid AM4 (207 mg, 88% yield). 1 H NMR (600 MHz, CDCl3-d3): δ H7.42 (dd, 2H), 7.07 (s, 1H), 6.85 (dd, 2H), 2.12 (td, 1H), 1.89 (m, 1H), 1.82 (m, 1H), 1.68 - 1.72 (m, 2H), 1.62 (m, 1H), 1.39 (m, 1H), 1.32 (t, 1H), 0.95 - 1.09 (m, 1H), 0.92 (dd, 6H), 0.83 (d, 3H); 13 13C NMR (151 MHz, CDCl3-d3) δ C 174.0, 156.3, 131.1, 121.7 (2 x C), 114.1 (2 x C), 50.7, 44.6, 39.5, 34.6, 32.3, 28.8, 24.0, 22.3, 21.4, 16.3; LC-MS m / z 293.21 [M + H] + 。

[0036] II. Pharmacodynamic Study of Compound AM4 on Dry Eye in Mice (1) Experimental Materials The experimental mice were male BALB / c mice, 6 - 8 weeks old, weighing 18 - 22 g, purchased from Hangzhou Ziyuan Experimental Animal Technology Co., Ltd. (Animal License No.: SCXK (Zhe) 2024 - 0004). All experimental reagents were commercially available products, mainly including normal saline, PBS, benzalkonium chloride (BAC), and sodium fluorescein. The experimental equipment mainly included animal surgical instruments and a handheld slit lamp.

[0037] (2) Experimental Methods Forty mice were randomly divided into four groups: a normal control group, a model group, an AM4 group, and a WS12 group, with 10 mice in each group. The BALB / c mice were locally instilled with 0.25%, 5 μL of BAC solution, once in the morning and once in the evening, for 14 consecutive days to establish a dry eye model in mice. All drug administrations were carried out 10 min after BAC; AM4 (0.03%) and WS12 (0.03%) were instilled once in the morning and once in the evening (2 μL) for 14 days.

[0038] The Schirmer test paper was used to measure tear secretion. The operation method was as follows: Gently take out the test paper, only holding the flat end of the test paper. Insert the round end of the test paper into the conjunctival sac of the lower eyelid of the mouse, ensuring that the test paper is firmly placed and avoiding sliding. The animal closes its eyes and keeps the test paper in the eye for 1 minute. After removing the test paper, refer to the scale on the test paper and record the distance of tear migration.

[0039] The corneal damage was observed using the sodium fluorescein staining method. Corneal epithelial damage scoring: The degree of corneal epithelial damage was assessed by instilling sodium fluorescein into the ocular surface. A 1% sodium fluorescein saline solution was instilled into the conjunctival sac of mice, and the conjunctival sac was rinsed with saline. Excess moisture around the eyes was wiped away with gauze. The staining of the mouse cornea was observed under cobalt blue light using a slit-lamp microscope, and photographs were taken. The ocular surface was divided into four quadrants according to different locations. The score ranged from 0 to 3 points based on the degree and area of ​​sodium fluorescein staining, with higher scores indicating larger and more severe staining areas. The total score for the four quadrants ranged from 0 to 12 points. The staining was further divided into four grades based on the degree and size of the staining area: no staining (0 points); scattered sparse punctate staining (1 point); relatively dense punctate staining (2 points); and patchy staining (3 points). If the number of puncta was uneven, the larger proportion was used. The total score for the four quadrants was 12 points.

[0040] (3) Experimental results The results are as follows Figure 7 As shown, compared with the control group, the tear secretion of mice in the model group was significantly reduced (tear length decreased from about 4.7 mm to 1.3 mm), the fluorescein staining score was significantly increased (from close to 0 points to about 6 points), and the corneal fluorescein staining photographs showed obvious punctate or patchy staining, indicating that the dry eye model was successfully established.

[0041] After drug intervention, all indicators in both the AM4 and WS12 groups showed significant improvement compared to the model group. The results indicated that, regarding tear secretion function (Figure 7A), the tear length in the AM4 group recovered to approximately 4.8 mm, significantly higher than the model group (P<0.01); the tear length in the WS12 group recovered to approximately 4.0 mm, significantly higher than the model group, but the tear secretion volume in the AM4 group increased by approximately 18% compared to the WS12 group, suggesting that AM4 is superior to the positive control drug in promoting tear secretion.

[0042] The assessment of corneal damage (Figure 7B) showed that the fluorescein staining score in the AM4 group decreased to approximately 2.2 points, and in the WS12 group it decreased to approximately 3.5 points, both significantly lower than the model group (P<0.01). Compared with the WS12 group, the staining score in the AM4 group decreased by approximately 21%, and as observed in the corneal morphology in Figure 7C, the corneal surface smoothness in the AM4 group was better than that in the WS12 group, with fewer and more localized fluorescein staining spots.

[0043] In summary, AM4 not only effectively improves dry eye symptoms but also outperforms the positive control drug WS12 in both promoting tear secretion and reducing corneal epithelial damage. In terms of the magnitude of the effect, AM4 improved tear length by approximately 18% and corneal staining score by approximately 21% compared to WS12. This result indicates that compound AM4 has good application potential in the treatment of dry eye, with superior tear secretion-promoting and corneal-protective effects compared to existing positive control drugs.

[0044] The above embodiments are exemplary and are intended to illustrate the technical concept and features of the present invention, so that those skilled in the art can understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A TRPM8 agonist compound or a pharmaceutically acceptable salt thereof, characterized in that, The structural formula of the compound is: 。 2. A TRPM8 agonist compound, or a pharmaceutically acceptable salt thereof, characterized in that, The structural formula of the compound is: 。 3. A TRPM8 agonist compound, or a pharmaceutically acceptable salt thereof, characterized in that, The structural formula of the compound is: 。 4. The TRPM8 agonist compound or a pharmaceutically acceptable salt thereof according to any one of claims 1 to 3, characterized in that: The pharmaceutically acceptable salt is any one or more of the following compounds: phosphate, camphor sulfonate, hydrochloride, hydrobromide, hydrofluoric acid, sulfate, nitrate, formate, acetate, propionate, oxalate, malonate, succinate, fumarate, maleate, lactate, malate, tartrate, citrate, picrate, methanesulfonate, trifluoromethanesulfonate, benzylsulfonate, and benzylsulfonate.

5. Use of the TRPM8 agonist compound according to any one of claims 1 to 4, or a pharmaceutically acceptable salt thereof, in the preparation of a medicament for treating dry eye syndrome.

6. A method for preparing a TRPM8 agonist compound, characterized in that, Includes the following steps: Step 1: Synthesize compound AM2 from compound AM1 using the method shown in the formula below; Step 2: Synthesize compound AM3 from compound AM2 using the path shown in the formula below; Step 3: Synthesize compound B2 from compound B1 using the method shown in the formula below; Step 4: Synthesize compound AM4 from compound B2 and compound AM3 according to the path shown in the formula below; 。 7. The method for preparing the TRPM8 agonist compound according to claim 6, characterized in that, In step 1, N-(4-hydroxyphenyl)acetamide AM1 was used as a raw material and under the presence of an alkaline reagent and an organic solvent, it underwent a substitution reaction with deuterated iodomethane. The reaction solution was extracted, dried, and purified to obtain compound AM2.

8. The method for preparing the TRPM8 agonist compound according to claim 6, characterized in that, In step 2, compound AM2 is heated and hydrolyzed under acidic conditions. After the reaction is complete, the system is adjusted to a strongly alkaline state, and compound AM3 is obtained by extraction, drying, and purification.

9. The method for preparing the TRPM8 agonist compound according to claim 6, characterized in that, In step 3, under inert gas protection, compound B1 reacts with oxalyl chloride in an organic solvent at low temperature via DMF catalysis. After removing the solvent, compound B2 is obtained.

10. The method for preparing the TRPM8 agonist compound according to claim 6, characterized in that, In step 4, under inert gas protection, compound AM3 and compound B2 undergo a condensation reaction in an alkaline reagent, at low temperature, and in an organic solvent. The reaction solution is then post-treated and purified to obtain compound AM4.

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