A class of oxadiazole compounds for protecting β cells to treat type II diabetes and preparation method and application thereof

Abstract

The present invention discloses a class of oxadiazole compounds for protecting β cells to treat type II diabetes, and a preparation method and application thereof. The structural formula of the oxadiazole compounds is shown in the general formula (I): #imgabs0# In the general formula (I), R1 is selected from one of the following: hydrogen, deuterium, chlorine, C1-C4 alkyl or substituted alkyl, and the substituent of the substituted alkyl is halogen; R1 is selected from one of the following: hydrogen, deuterium, C1-C4 alkyl or substituted alkyl. The present invention discloses a new compound shown in the general formula (I) and a preparation method thereof, which can inhibit endoplasmic reticulum stress and protect β cells to produce a therapeutic effect on diabetes, and can be used to prepare a drug for treating diabetes. The embodiments of the present invention have achieved excellent technical effects through experimental verification.

Description

Technical Field

[0001] The present invention relates to the field of pharmaceutical chemistry, in particular to an oxadiazole compound for protecting beta cells to treat type II diabetes, and a preparation method and application thereof. Background Art

[0002] Diabetes mellitus is a group of metabolic diseases characterized by abnormally high blood sugar levels over a long period of time. It has become a serious public health problem and has brought huge social and economic burdens to society. Dysfunction or death of insulin-secreting β-cells is a key factor in the pathogenesis of type 1 (T1D) and type 2 (T2D) diabetes. Increasing evidence shows that endoplasmic reticulum (ER) stress causes protein misfolding in the ER, leading to β-cell dysfunction, which in turn causes pancreatic β-cell dysfunction and even apoptosis. Therefore, preventing functional β-cell death by targeting ER stress is a promising approach to treating diabetes. Unfortunately, there are currently no antidiabetic drugs that can inhibit β-cell dysfunction and death.

[0003] In T2D, due to the high metabolic demands of obesity and insulin resistance, β cells are forced to synthesize more insulin, which leads to protein folding beyond the cell's capacity, ultimately causing ER stress and β cell dysfunction and death. In addition, common causes of β cell dysfunction and death in T2D include lipotoxicity, glucotoxicity, oxidative stress, amyloid deposition, and insulin mutations, which are associated with unresolved chronic ER stress.

[0004] Although ER stress is an important factor leading to β-cell dysfunction and death, to date, only a few small molecules have been reported to be protective against β-cells after ER stress. The main reason for this situation may be the unique characteristics of β-cells. When blood glucose levels rise after food intake, β-cells are produced in the body and insulin is rapidly secreted. To achieve this function, the synthesis of proinsulin protein is 25 times higher under glucose stimulation. The surge in proinsulin synthesis puts a heavy burden on the protein folding capacity of the ER; therefore, β-cells are particularly susceptible to ER stress. In addition, the existing small molecules that protect β-cells still have the problem of low potency, and the EC50 values ​​usually range from single digits to double digits.

[0005] Oxadiazoles are cyclic compounds with one oxygen, two nitrogen and two carbon atoms. These compounds were called "furodiazoles" in ancient literature. Aromatic heterocyclic systems form the key part of many biologically active drug molecules. Aromatic heterocyclic rings are of wide importance because they have structural similarities with many biological parts present in the human body such as nucleic acids, hormones, neurotransmitters, etc. Among many heterocyclic rings, many pharmaceutical products are composed of oxadiazoles as the main drug component. Oxadiazoles exist in four main forms, namely 1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,2,5-oxadiazole and 1,3,4-oxadiazole. Among them, 1,3,4-oxadiazole derivatives have certain anticancer activity. The affinity and efficacy of the 1,2,4-oxadiazole ring for central muscarinic receptors are the best and have certain antibacterial activity. These activities are due to the presence of -N=CO- bonds, so oxadiazoles and their derivatives have attracted widespread attention from chemists for the preparation of different biologically active drugs. Summary of the invention

[0006] Purpose of the invention In order to solve the problem that endoplasmic reticulum stress leads to β-cell dysfunction or apoptosis and then causes type II diabetes, the present invention uses a class of 1,2,4-oxadiazole compounds to inhibit endoplasmic reticulum stress and protect β-cells to produce a therapeutic effect on diabetes. The present invention also provides a specific preparation method of the compound, and the compound and the product prepared with it as raw material have potential application prospects in the development of anti-diabetic drugs.

[0007] An oxadiazole compound represented by general formula (I) or a pharmaceutically acceptable salt thereof, the structural formula of the compound is as follows:

[0008]

[0009] In the general formula (I), R 1 is selected from the following: hydrogen, deuterium, chlorine, C1-C4 alkyl or substituted alkyl, the substituent of the substituted alkyl is halogen; R 1 Selected from one of the following: hydrogen, deuterium, C1-C4 alkyl or substituted alkyl.

[0010] Furthermore, the compound of the present invention is selected from A1 to A8:

[0011]

[0012] The synthesis method of the oxadiazole compound comprises the following steps:

[0013] (1) Synthesizing substituted N'-hydroxy-benzoimide using substituted benzonitrile and hydroxylamine hydrochloride as raw materials;

[0014]

[0015] (2) Using substituted benzoic acid and substituted N'-hydroxy-benzamide as raw materials to synthesize the oxadiazole compound represented by the general formula (I), wherein the substituent R on the benzene ring of the substituted benzoic acid is 1 With the general formula (I) R 1 The same, the substituent R on the benzene ring of the substituted N'-hydroxy-benzamide 2 With the general formula (I) R 2 same.

[0016]

[0017] Furthermore, in step (1), the molar ratio of substituted benzonitrile to hydroxylamine hydrochloride is 1:0.5-2; and in step (2), the molar ratio of substituted benzoic acid to substituted N'-hydroxy-benzimide is 1:0.5-2.

[0018] Furthermore, the reaction in step (1) is carried out in the presence of NaOH in an ethanol solvent, the reaction temperature is 55-65° C. and the reaction is tracked by TLC until completion, and the molar ratio of NaOH to the hydroxylamine hydrochloride raw material is 4-6:1.

[0019] Furthermore, the reaction in step (2) is carried out in an organic solvent in the presence of a catalyst, the molar ratio of the catalyst to the substituted benzoic acid is 1 to 1.2:1, and the concentration of the substituted benzoic acid in the organic solvent is 0.2 to 0.4 mmol / mL.

[0020] In step (2), in addition to dimethylformamide, dimethyl sulfoxide can also be selected as the solvent when synthesizing oxadiazole. Since dimethyl sulfoxide has good water absorption, it is more conducive to the forward reaction, thereby improving the yield. However, dimethyl sulfoxide has certain toxicity. Heating in the presence of benzoic acid will produce a small amount of impurities such as methyl mercaptan, formaldehyde, dimethyl sulfide, and methanesulfonic acid. Therefore, dimethyl sulfoxide can be used to replace dimethylformamide.

[0021] In step (2), in addition to N'N-carbonyldiimidazole, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDC) and 1-hydroxybenzotriazole (HOBT) can be selected as the catalytic reagent to activate the carboxyl group during the synthesis of oxadiazole.

[0022] The invention relates to the use of the oxadiazole compound or a pharmaceutically acceptable salt thereof in the preparation of a drug for protecting β cells to treat type II diabetes.

[0023] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the present invention discloses a new compound represented by general formula (I) and a preparation method thereof, which can inhibit endoplasmic reticulum stress and protect β cells to produce a therapeutic effect on diabetes, and can be used to prepare drugs for treating diabetes. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the nuclear magnetic hydrogen spectrum characterization diagram of compound A6 of the present invention;

[0025] Figure 2 is the nuclear magnetic hydrogen spectrum characterization diagram of compound A5 of the present invention;

[0026] Figure 3 is a nuclear magnetic hydrogen spectrum characterization diagram of compound A4 of the present invention;

[0027] Figure 4 This is the nuclear magnetic hydrogen spectrum characterization diagram of compound A3 of the present invention;

[0028] Figure 5 is the nuclear magnetic hydrogen spectrum characterization diagram of compound A8 of the present invention;

[0029] Figure 6 is the nuclear magnetic hydrogen spectrum characterization diagram of compound A1 of the present invention;

[0030] Figure 7 This is the nuclear magnetic hydrogen spectrum characterization diagram of compound A2 of the present invention;

[0031] Figure 8 This is the H NMR spectrum characterization diagram of compound A7 of the present invention. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0033] Embodiment 1:

[0034] 1) Synthesis of N'-hydroxy-benzamide

[0035] In 50ml beaker A, weighed hydroxylamine hydrochloride (1.390g, 0.02mol) and ethanol (95%) were added to prepare a 1mol / L solution. In 50ml beaker B, weighed solid sodium hydroxide (4.008g, 0.10mol) and ethanol (95%) were added to prepare a 1mol / L solution. The solutions in beakers A and B were stirred magnetically at the same time. The solution in beaker B was slowly added to beaker A and stirred magnetically to produce a large amount of white precipitate. After filtration, the clear solution was placed in a 100ml round-bottom flask and weighed benzonitrile (2.066g, 0.02mol) was added. The solution was stirred magnetically and heated in an oil bath at 60℃. At the same time, TLC was used to track the reaction process throughout the process. After repeated attempts, it was found that the developing agent PE: EA = 2:1 can be accurately separated. The ethyl acetate layer was retained after extraction with ethyl acetate and water three times, and then washed with saturated brine three times and dried with anhydrous sodium sulfate. The sodium sulfate solid was filtered out and the organic solvent was removed by rotary evaporation. 1.132 g of light yellow crystals were obtained, with a yield of 83.5%.

[0036]

[0037] 2) Synthesis of 5-(3-methylphenyl)-3-phenyl-1,2,4-oxadiazole

[0038] In a 25ml round-bottom flask, weigh m-toluic acid (0.068g, 0.0005mol) and N'N-carbonyldiimidazole (0.097g, 0.0006mol) were added in sequence, and 1.67ml of dimethylformamide was added dropwise. Stir magnetically, and heat in an oil bath at 25℃ for 1h. Weigh N'-hydroxy-benzamide (0.00055mol) and heat at 50℃. Weigh sodium hydroxide (0.024g, 0.0006mol) and add it to the round-bottom flask. At this time, the reaction liquid turns light yellow. Extract with ethyl acetate and water three times to retain the ethyl acetate layer, then wash with saturated brine three times and dry with anhydrous sodium sulfate. Filter out the sodium sulfate solid and evaporate to remove the organic solvent. The pure product was separated by column chromatography (stationary phase: silica gel (200-300 mesh), mobile phase: n-hexane, ethyl acetate (V / V=15:1)) to obtain 0.026 g of the final product with a yield of 57.6%.

[0039]

[0040] Example 2: Substrate expansion of 5,3-diphenyl-1,2,4-oxadiazole derivatives

[0041]

[0042] Table 1

[0043]

[0044] Example 1 discloses the details of the synthesis of chemical A2.

[0045] The synthesis of compounds A1-A8 was repeated in Example 1, except that "in step 1), benzonitrile was replaced with an equal molar amount of substituted benzonitrile to synthesize substituted N'-hydroxy-benzoimide, and in step 2), m-toluic acid was replaced with an equal molar amount of substituted benzoic acid, and the corresponding substituents are listed in Table 1".

[0046] In the synthesis of compounds A1 and A3, in order to improve the reaction yield, the post-treatment step of step 2) was improved to a certain extent, specifically: after extracting three times with ethyl acetate and water, the ethyl acetate layer was retained and washed three times with saturated brine, and a small amount of cold distilled water was directly added to the reaction system. At this time, a large amount of white crystals instantly precipitated in the light yellow solution, and the pure product was obtained by column chromatography separation.

[0047] In the synthesis of chemical A5, after A5 was synthesized and prepared for separation by column chromatography, it was found through TLC that the shift ratio between the sample point and the impurity point was greater than 0.8 at a certain ratio of developing agent (PE:EA=5:1). It was decided to separate and purify the product by HPTLC, with a yield of 36.3%.

[0048] When synthesizing A4, extending the reaction time of step 2) by 1 h can improve the yield.

[0049] According to the above process, the yields of compounds A1-A8 are listed in Table 1.

[0050] The nuclear magnetic hydrogen spectrum characterization diagram of compounds A1-A8 of the present invention is shown in Figure 1-Figure 8 , and H NMR spectrum data are listed in Table 3.

[0051] Biological evaluation experiment

[0052] (1) Activity analysis and detection methods

[0053] β-cell detection method: INS-13×10 3 Cells / well were seeded in 384-well plates and treated with the indicated concentrations of compounds. After 3 days of treatment, the culture medium was aspirated and 20 μL / well of CellTiter-Glo reagent (Promega, WI, USA) was added to detect intracellular ATP levels. Cell viability was measured using an EnVision microplate reader (PerkinElmer, MA, USA). Each experiment was performed 3 times under each condition, and 3 independent experiments were performed.

[0054] Measured EC 50 The values ​​are shown in Table 2 below. From the experimental results, it can be seen that the example compounds of the present invention have a strong inhibitory activity on β cell activity.

[0055] Table 2 EC of the compounds of the present invention on INS-1β cells 50 Measurements

[0056]

[0057]

[0058] Table 3 Nuclear magnetic resonance hydrogen spectrum data of the compounds of the present application

[0059]

[0060]

[0061] The contents described in this specification are merely an enumeration of implementation forms of the inventive concept, and the protection scope of the present invention should not be regarded as being limited to the specific forms described in the embodiments.

Claims

1. Use of an oxadiazole compound or a pharmaceutically acceptable salt thereof in the preparation of a drug for protecting β cells, characterized in that: The compound is selected from one of the following: 。

Images