A kind of synthesis method of monohydroxyacetylated hesperidin

Abstract

The present invention discloses a method for synthesizing monohydroxyacetylated hesperidin. The method uses hesperidin as a starting material, firstly uses acetic anhydride to protect all hydroxyl groups and then synthesizes acetylated hesperidin, and after catalytic transfer hydrogenation of acetylated hesperidin with an iridium metal catalyst, the carbonyl group on the chromone structure of acetylated hesperidin is highly chemically selectively reduced to obtain a target product monohydroxyacetylated hesperidin having only one hydroxyl group. The present invention has simple operation steps, mild conditions, high catalytic activity, high chemical selectivity, and high yield of the target compound. The monohydroxyacetylated hesperidin obtained by the present invention can be further connected with a hydrophobic drug molecule, and after selectively removing the acetyl group, an amphiphilic drug molecule is formed to further be made into a nano-prodrug to achieve efficient drug delivery, so that hesperidin and the hydrophobic drug molecule can simultaneously exert their pharmacological effects, or can be efficiently connected with other functional structures to achieve the pharmacological effects of hesperidin while exerting other effects, and can also achieve the modification of the physical properties of hesperidin.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and particularly relates to a method for synthesizing monohydroxyacetylated hesperidin. Background Art

[0002] Hesperidin is a flavonoid glycoside rich in citrus fruits with antioxidant and anti-inflammatory activities. Increasing evidence shows that hesperidin can inhibit tumor proliferation by inducing apoptosis and cell cycle arrest, inhibiting tumor cell migration and angiogenesis. In addition, hesperidin can enhance the anti-tumor effect of doxorubicin, cytarabine, tamoxifen or quercetin, and reduce the hepato-renal toxicity induced by cisplatin, lipopolysaccharide, sodium arsenite, cyclophosphamide, methotrexate and acrylamide. However, due to its poor water solubility and poor bioavailability, the clinical application of hesperidin is greatly limited. At present, the delivery of hesperidin can only be achieved by nanoparticle encapsulation, but this method is extremely costly, has a low drug loading and is inefficient. Therefore, by connecting molecules with good water solubility and high bioavailability to hesperidin or by making high-drug-loaded nanoformulations, it becomes an important solution for its efficient delivery and realization of the above functions.

[0003] However, hesperidin molecules are chemically inert and have poor reactivity, which makes it extremely difficult to connect with other molecules. Hydroxyl groups can be used as good active modification sites, but the different active levels of each hydroxyl group in the hesperidin molecule, the large number of hydroxyl groups and the distribution of multiple positions in the molecule make it difficult to modify its structure at a fixed point. It is of great value to design and synthesize a hesperidin molecule with only one hydroxyl active site and protect other hydroxyl groups. Acetylation protection of hydroxyl groups is the most common way to protect hydroxyl groups, and is widely used in organic synthesis due to the easy selective removal of acetyl groups. The simplest method for synthesizing monohydroxy acetylated hesperidin is to acetylate all hydroxyl groups in the molecule and then reduce the carbonyl group at the chromone position to a hydroxyl group, but there are currently no reports of related success. One of the important reasons is that the chromone region of the hesperidin molecule is not active enough or lacks chemical selectivity when using traditional reduction methods, so that the keto carbonyl group on the acetylated hesperidin cannot be reduced or the acetyl group (part of the acetyl group) will also be reduced. Therefore, finding a suitable reduction method or reducing agent is the key to the successful synthesis of this type of monohydroxy acetylated hesperidin, which has important research value. Summary of the invention

[0004] The purpose of the present invention is to overcome the difficulty that only a single carbonyl in the chromone region of acetylated hesperidin having 9 carbonyl groups is selectively reduced, and to provide a method for synthesizing monohydroxyacetylated hesperidin with high activity and high chemical selectivity.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present invention comprises the following steps:

[0006]

[0007] (1) protecting all hydroxyl groups on hesperidin 1 with an acetylation agent to obtain acetylated hesperidin 2;

[0008] (2) Acetylated hesperidin 2 is reduced to a hydroxyl group under the action of an iridium metal catalyst 3 to obtain monohydroxy acetylated hesperidin.

[0009] In the above step (1), the acetylating agent is any one of acetic anhydride, acetyl chloride and glacial acetic acid.

[0010] In the above step (2), the amount of iridium metal catalyst 3 is preferably 1% to 2% of 2 mol of acetylated hesperidin. The iridium metal catalyst 3 is synthesized by the method described in the document "Gang Zhou, Ahmed H. Aboo, Craig M. Robertson, Ruixia Liu, Zhenhua Li, Konstantin Luzyanin, Neil G. Berry, Weiping Chen, and Jianliang Xiao, ACS Catalysis 2018 8 (9), 8020-8026".

[0011] In the above step (2), the reaction temperature for reducing the keto carbonyl group to the hydroxyl group is 20 to 40°C.

[0012] In the above step (2), the solvent used to reduce the ketone carbonyl to a hydroxyl group is selected from any one of pyridine, ethyl acetate, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide, dichloromethane and chloroform.

[0013] The beneficial effects of the present invention are as follows:

[0014] The present invention uses a simple and easily available iridium metal catalyst to complete the highly chemically selective transfer hydrogenation of acetylated hesperidin with 9 carbonyl groups, and obtains monohydroxy acetylated hesperidin in which only the carbonyl groups in the chromone region are reduced to hydroxyl groups. The product can be connected with other molecules with good water solubility and high bioavailability through a one-step reaction through a simple chemical reaction, or can be further made into a high-drug-loading nano-preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a diagram showing the effect of THE nanomedicine prepared by monohydroxyacetylated hesperidin on inhibiting the proliferation of bladder cancer cells.

[0016] Figure 2 This is a picture showing the effect of THE nanomedicine prepared by monohydroxyacetylated hesperidin in inhibiting bladder cancer in mice.

[0017] Figure 3This is a diagram showing the effect of THE nanomedicine prepared by monohydroxyacetylated hesperidin in reducing the hepatotoxicity caused by the use of triptolide alone. DETAILED DESCRIPTION

[0018] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments, but the protection scope of the present invention is not limited to these embodiments.

[0019] In the following examples, the specific synthesis method of the iridium metal catalyst 3 used is: take oxazoline methyl ester (100 mg, racemic), pentamethylcyclopentadienyl iridium dichloride dimer (170 mg), sodium acetate (402 mg) and place it in a 25 ml reaction tube, double-row tube vacuum filling argon gas operation three times, add water (1 mL), dichloromethane (10 mL), and react at room temperature for 24 hours. The reaction solution is filtered through diatomaceous earth and washed with water and saturated brine respectively, and then dried with anhydrous sodium sulfate. After drying, it is recrystallized with a mixed solution of ether and n-hexane in a volume ratio of 1:1 to obtain a yellow solid iridium metal catalyst 3 (165 mg, 62%). The synthetic route is as follows:

[0020]

[0021] The structural characterization data of the obtained iridium metal catalyst 3 are: 1 H NMR (400 MHz, CDCl 3 )δ8.38(d,J=7.6Hz,2H),7.62–7.56(m,1H),7.49–7.42(m,2H),4.88(dd,J=11 .0,8.2Hz,1H),4.84–4.75(m,1H),4.51(dd,J=11.9,8.1Hz,1H),1.64(s,15H). 13 C NMR (101 MHz, CDCl 3 )δ175.01,167.38,133.32,129.99,128.27,124.14,85.15,72.05,71.28,9.21.HRMS forC 20 H 23 C1R 3 [M+Na] + : m / z theoretical value 576.0894; measured value 576.0889.

[0022] Example 1

[0023]

[0024] (1) Hesperidin 1 (6.1 g) was dissolved in pyridine (50 mL), and freshly distilled acetic anhydride (50 mL) was added to the solution, and the mixture was reacted at 90° C. for 24 hours. After the reaction solution was cooled to room temperature, the solvent was dried by rotary evaporation, 200 mL of water was added, and the mixture was fully stirred. The water was filtered, and the solid residue was dissolved in chloroform and dried over anhydrous sodium sulfate. After drying, the crude product was dried by rotary evaporation to obtain a crude product. The crude product was subjected to column chromatography using a mixed solution of n-hexane and ethyl acetate in a volume ratio of 3:1 as a developing solvent to obtain pure white solid acetylated hesperidin 2 (7.1 g, 75%), and its structural characterization data are as follows: 1 H NMR (400 MHz, CDCl 3 )δ7.36(d,J=8.8Hz,1H),7.16(d,J=2.3Hz,1H),7.00(d,J=8.5Hz,1H),6.47(d,J=2.5Hz,1H),6.31(d,J=2.4Hz,1H ),5.48–5.37(m,1H),5.25(d,J=16.1Hz,6H),5.02(t,J=10.2Hz,1H),4.69(s,1H),3.92–3.90(m,1H),3.86(s,3H), 3.81(dt,J=11.7,3.3Hz,2H),3.64(td,J=11.6,10.4,4.9Hz,1H),2.99(dd,J=16.6,12.9Hz,1H),2.76(dd,J=16.6 ,3.0Hz,1H),2.38(s,3H),2.33(s,3H),2.09(s,3H),2.08(s,3H),2.04(s,9H),1.96(s,3H),1.15(d,J=6.3Hz,3H). 13 C NMR (101 MHz, CDCl 3 )δ188.73,170.19,170.03,169.85,169.34,169.15,168.87,163.80,161.89 ,151.89,151.59,139.93,130.74,124.95,121.18,112.45,109.60,105.91,1 02.16,98.09,97.59,78.68,77.22,73.26,72.45,70.87,70.80,69.36,68.97 ,68.61,66.66,66.15,56.04,21.05,20.80,20.66,20.63,20.60,17.28.HRMS C 44 H 50 O 23 [M+H] +: m / z theoretical value 946.2723; measured value 946.2743.

[0025] (2) Take acetylated hesperidin 2 (2.0 g, 2.11 mmol) and iridium metal catalyst 3 (13 mg, 0.021 mmol) and place them in a reaction tube. The double-row tube is evacuated and filled with argon three times. After adding dichloromethane (5 mL) to dissolve, formic acid-triethylamine azeotrope (5 mL) is added and reacted at room temperature for 10 hours. The reaction solution is washed with water, dried with anhydrous sodium sulfate, and the solvent is dried to obtain a crude product. After column chromatography (the eluent is a mixture of ethyl acetate and n-hexane in a volume ratio of 3:1), the pure product is obtained as a yellow solid monohydroxy acetylated hesperidin (1.6 g, 79%), and its structural characterization data are as follows: 1 H NMR (400 MHz, CDCl 3 )δ7.33–7.28(m,1H),7.16(t,J=2.3Hz,1H),7.05–6.97(m,1H),6.48(d,J=2.5Hz,1H),6.32(d,J=2.4Hz,1H) ,5.49–5.35(m,1H),5.30–5.10(m,7H),5.02(t,J=10.0Hz,1H),4.70(s,1H),3.95–3.87(m,1H),3.86(s,3H) ,3.85–3.75(m,1H),3.64(td,J=11.6,10.4,4.9Hz,1H),3.69–3.58(m,1H),3.11–2.92(m,1H),2.79–2.66(m ,1H),2.38(s,3H),2.35(s,3H),2.09(s,3H),2.08(s,3H),2.04(s,9H),1.96(s,3H),1.15(d,J=6.2Hz,3H). 13 C NMR (101 MHz, CDCl 3 )δ170.17,170.01,169.77,169.44,169.33,169.14,168.85,163.98,163.80,161 .88,151.88,151.58,139.93,130.74,124.94,121.18,112.45,109.60,105.90,1 02.16,98.08,97.58,78.67,73.26,72.44,70.87,70.80,69.35,68.97,68.63,66 .66,66.14,56.03,53.81,21.04,20.79,20.75,20.64,20.61,20.59,17.27.HRMS C 44 H52 O 23 [M+H] + : m / z theoretical value 948.2919; measured value 948.2932.

[0026] Application examples of monohydroxyacetylated hesperidin

[0027]

[0028] Triptolide is a class of highly anti-tumor active molecules extracted from natural products (JT Wen, J. Liu, L. Wan, L. Xin, JC Guo, YQ Sun, X. Wang, J. Wang, Int Immunopharmacol 2022, 106, 108616; P. Noel, DD Von Hoff, AK Saluja, M. Velagapudi, E. Borazanci, H. Han, Trends in pharmacological sciences 2019, 40, 327.), but it has strong hydrophobicity, low bioavailability and high toxicity (M. Yanchun, W. Yi, W. Lu, Q. Yu, Y. Jian, K. Pengzhou, Y. Ting, L. Hongyi, W. Fang, C. Xiaolong, C. Yongping, Eur J Pharmacol 2019, 851, 43; L. Zhao, Z. Lan, L. Peng, L. Wan, D. Liu, X. Tan, C. Tang, G. Chen, H. Liu, Cell Prolif 2022, 55, e13278; J. Wen, J. Liu, X. Wang, J. Wang, Phytother Res 2021, 35, 4334.). Monohydroxyacetylated hesperidin (I) was connected to triptolide modified with succinic anhydride, and after selective deprotection of the acetyl group, an amphiphilic THE molecule was obtained, which was further self-assembled into THE nanoprodrug.

[0029] Figure 1 The experimental results show that THE nanomedicine prepared by monohydroxyacetylated hesperidin can effectively inhibit the proliferation of bladder cancer cells. 5637 cells were treated with a specified dose of THE nanomedicine for 14 hours and stained with crystal violet. Compared with the control group without the addition of nanomedicine, THE nanomedicine prepared by monohydroxyacetylated hesperidin can significantly inhibit the proliferation of bladder cancer cells at 2μM, and the inhibition is more obvious at 4μM.

[0030] Figure 2This is an experimental model and result that THE nanomedicine prepared by monohydroxyacetylated hesperidin can significantly inhibit bladder cancer in mice. Among them, A is a schematic diagram of the establishment and treatment of the bladder cancer model, showing that the bladder cancer model was established in 7 days, and the treatment period was 1 to 15 days after the model was determined, and the patient was killed after 20 days; B is that the THE nanomedicine prepared by monohydroxyacetylated hesperidin can efficiently enter the tumor through tail vein injection, and the small animal imaging results show that the THE nanomedicine can be efficiently delivered to the tumor site of the mouse; C is that the mouse was killed after 20 days of treatment, and the size comparison of the obtained bladder cancer tissue can show that the THE nanomedicine can effectively inhibit bladder cancer in mice.

[0031] Figure 3 The experimental results show that THE nanomedicine prepared by monohydroxyacetylated hesperidin can effectively reduce the hepatotoxicity caused by triptolide alone. C57 mice were injected with PBS, 8.5mg / kg hesperidin, 5mg / kg triptolide, and 15mg / kg THE nanomedicine via the tail vein for 24 hours, and blood and biochemical indicators were analyzed, n=3; scale size 50μm.*, p<0.05; **, p<0.01; ***, p<0.001; AE: blood and biochemical indicators, the results of mice treated with triptolide alone were obviously abnormal, showing that triptolide had obvious toxicity to the mouse liver, but the results of hesperidin and nanomedicine were compared with the control group, showing that the two had no obvious toxicity to the mouse liver, which also reflected that THE nanomedicine prepared by monohydroxyacetylated hesperidin significantly reduced hepatotoxicity compared with triptolide.

[0032] comprehensive Figures 1 to 3 The results show that THE nanomedicine prepared by monohydroxyacetylated hesperidin can play the synergistic inhibitory effect of hesperidin and triptolide on bladder cancer, which not only improves the bioavailability of triptolide, but also utilizes the high anti-tumor activity of triptolide, while also reducing the high toxicity of triptolide through hesperidin.

Claims

1. A method for synthesizing monohydroxyacetylated hesperidin, Features The following steps are involved: (1) protecting all hydroxyl groups on hesperidin 1 with an acetylation agent to obtain acetylated hesperidin 2; (2) Acetylated hesperidin 2 is reduced to a hydroxyl group under the action of an iridium metal catalyst 3 to obtain monohydroxy acetylated hesperidin.

2. The method for synthesizing monohydroxyacetylated hesperidin according to claim 1, Features: In step (1), the acetylating agent is any one of acetic anhydride, acetyl chloride and glacial acetic acid.

3. The method for synthesizing monohydroxyacetylated hesperidin according to claim 1, Features: In step (2), the amount of the iridium metal catalyst 3 is 1% to 2% of 2 mol of acetylated hesperidin.

4. The method for synthesizing monohydroxyacetylated hesperidin according to claim 1, Features: In step (2), the reaction temperature for reducing the ketone carbonyl group to the hydroxyl group is 20 to 40°C.

5. The method for synthesizing monohydroxyacetylated hesperidin according to claim 1, Features: In step (2), the solvent used to reduce the ketone carbonyl to a hydroxyl group is selected from any one of pyridine, ethyl acetate, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide, dichloromethane and chloroform.

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