Novel Compounds and MRI Contrast Agents Containing the Same

Abstract

The present invention provides a novel compound and an MRI contrast agent containing the same. Based on its excellent kinetic stability, the compound of the present invention can minimize the side effects of the MRI contrast agent caused by the leakage of gadolinium ions in the body, and has a very high degree of contrast enhancement in the liver compared to other organs in biological MRI images, and can be effectively used as an MRI contrast agent for diagnosing liver diseases.

Description

Technical Field

[0001] The present invention relates to a novel compound and an MRI contrast agent containing the same. Specifically, it relates to a novel compound having high in vivo stability and capable of diagnosing liver diseases and an MRI contrast agent containing the same. Background Art

[0002] Magnetic Resonance Image (hereinafter, MRI) is a method of obtaining images of human anatomy, physiology, and biochemistry by utilizing the phenomenon that the distribution of hydrogen atoms among tissues in the body is different and the relaxation of hydrogen atoms in a magnetic field.

[0003] Different from CT or PET, MRI does not use radiation harmful to the human body, but uses magnetic field gradients and radio waves under a strong magnetic field to create images of the inside of the body. Therefore, it is non-invasive, has high resolution, and is very suitable for soft tissue examination.

[0004] To use this MRI device more precisely, a contrast agent is injected into an object to obtain an MRI image. The contrast between tissues on the MRI image occurs because the relaxation of the nuclear spins of water molecules in the tissue returning to the equilibrium state is different for each tissue.

[0005] The contrast agent uses paramagnetic or superparamagnetic substances to affect the relaxation effect, thereby expanding the difference in relaxation rates between tissues, causing changes in MRI signals, and making the contrast between tissues clearer.

[0006] Currently, the most commonly used contrast agent in clinical practice is a contrast agent based on gadolinium (Gd) chelate. Among them, the contrast agent based on a linear chelate structure is used as a clinical liver-specific MRI contrast agent for the MRI image diagnosis of microscopic liver cancer and other liver diseases.

[0007] However, commercially available liver-specific MRI contrast agents have low in vivo stability due to their linear chelate structure, so they may leak gadolinium ions into the body, thus limiting their availability.

[0008] Contents of the Invention

[0009] Technical Problems to be Solved by the Invention

[0010] An object of the present invention is to provide a novel compound having high in vivo stability and capable of diagnosing liver diseases.

[0011] Another object of the present invention is to provide an MRI contrast agent containing the compound.

[0012] Technical Solutions for Solving the Problems

[0013] According to the present invention, there is provided a compound represented by the following Chemical Formula 1.

[0014] Chemical Formula 1:

[0015] ,

[0016] In the Chemical Formula 1,

[0017] R represents -COO - , -CH2COO - or -CH2CH2COO - .

[0018] In one embodiment, the present invention is characterized in that the Chemical Formula 1 is represented by the following Chemical Formula 1-1, 1-2 or 1-3.

[0019] Chemical Formula 1-1:

[0020]

[0021] Chemical Formula 1-2:

[0022]

[0023] Chemical Formula 1-3:

[0024]

[0025] In one embodiment, the present invention is characterized in that the compound specifically binds to liver tissue.

[0026] Furthermore, according to the present invention, there is provided an MRI contrast agent comprising the compound represented by the Chemical Formula 1.

[0027] In one embodiment, the MRI contrast agent can be used for the diagnosis of liver diseases, and more specifically, for the diagnosis of liver metastases of cancer, hepatic cysts, liver cancer or biliary obstruction.

[0028] In one embodiment, the present invention is characterized in that the relaxation rate of the MRI contrast agent in 4.7T magnetic resonance images is 5 mM -1 s -1 to 10 mM -1 s -1 .

[0029] Effects of the Invention

[0030] The compound of the present invention has an appropriate relaxation rate and excellent kinetic stability, thereby improving in vivo stability, and when used as an MRI contrast agent, can minimize the side effects of the MRI contrast agent caused by the leakage of gadolinium ions in the body.

[0031] Meanwhile, compared with other organs in the biological MRI image, the compound of the present invention has a very high degree of contrast enhancement in the liver and can be effectively used as an MRI contrast agent for diagnosing liver diseases. Description of the Drawings

[0032] Figure 1 1H NMR (500 MHz) spectrum of compound (1) produced during the synthesis of the compound of the present invention. 1 1H NMR (500 MHz) spectrum of compound (2) produced during the synthesis of the compound of the present invention.

[0033] Figure 2 1H NMR (500 MHz) spectrum of compound (2) produced during the synthesis of the compound of the present invention. 1 1H NMR (500 MHz) spectrum of compound (2) produced during the synthesis of the compound of the present invention.

[0034] Figure 3 Showing the HR-FABMS (positive mode) analysis result of compound (4) produced during the synthesis of the compound of the present invention.

[0035] Figure 4 Showing the HPLC analysis result of the compound (Gd-suc) of Example 1 of the present invention.

[0036] Figure 5 Showing the HR-FABMS (positive mode) analysis result of the compound (Gd-suc) of Example 1 of the present invention.

[0037] Figure 6 Showing the HR-ESIMS (negative mode) analysis result of the compound (Gd-suc) of Example 1 of the present invention.

[0038] Figure 7 1H NMR (500 MHz) spectrum of compound (6) produced during the synthesis of the compound of the present invention. 1 1H NMR (500 MHz) spectrum of compound (6) produced during the synthesis of the compound of the present invention.

[0039] Figure 8 1H NMR (500 MHz) spectrum of compound (7) produced during the synthesis of the compound of the present invention. 1 1H NMR (500 MHz) spectrum of compound (7) produced during the synthesis of the compound of the present invention.

[0040] Figure 9 Showing the HR-ESIMS (negative mode) analysis result of compound (9) produced during the synthesis of the compound of the present invention.

[0041] Figure 10 Showing the HR-ESIMS (negative mode) analysis result of the compound (Gd-glu) of Example 2 of the present invention.

[0042] Figure 11 Show the evaluation results of the kinetic stability of the compounds of the embodiments of the present invention and commercially available contrast agents.

[0043] Figure 12 An image showing the in vivo T1 MRI liver contrast enhancement phenomenon of the compound (Gd-suc) of Example 1 of the present invention over time.

[0044] Figure 13 An image showing the in vivo T1 MRI liver contrast enhancement phenomenon of the commercially available contrast agent Primovist over time.

[0045] Figure 14 An image showing the in vivo T1 MRI liver contrast enhancement phenomenon of the compound (Gd-glu) of Example 2 of the present invention over time.

[0046] Figure 15 An image showing the in vivo T1 MRI liver contrast enhancement phenomenon of the compound (Gd-suc) of Example 1 of the present invention within 5 minutes.

[0047] Figure 16 Show the results of the cell viability experiment after 24 hours of the compound (Gd-suc) of Example 1 of the present invention, the commercially available liver contrast agent Primovist, and Multihance with different concentrations. Detailed implementation manners

[0048] Hereinafter, the terms used in the present application are only used to illustrate specific embodiments and do not limit the present invention. Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. Terms such as those defined in a common dictionary should be interpreted as having a meaning consistent with the meaning in the relevant technical context, and should not be interpreted as ideal or overly formal meanings unless clearly defined in the present application.

[0049] The compound of an embodiment of the present invention is represented by the following Chemical Formula 1.

[0050] Chemical Formula 1:

[0051]

[0052] In the Chemical Formula 1, R represents -COO - , -CH2COO - or -CH2CH2COO -Preferably, the R may be -CH2COO - or -CH2CH2COO - More preferably, the R may be -CH2COO -

[0053] According to an example of the present invention, the chemical formula 1 may be represented by the following chemical formula 1-1.

[0054] Chemical formula 1-1:

[0055]

[0056] According to an example of the present invention, the chemical formula 1 may be represented by the following chemical formula 1-2.

[0057] Chemical formula 1-2:

[0058]

[0059] According to an example of the present invention, the chemical formula 1 may be represented by the following chemical formula 1-3.

[0060] Chemical formula 1-3:

[0061]

[0062] The compound of the present invention represented by the chemical formula 1-1, 1-2 or 1-3 is synthesized by complexing gadolinium with a ligand having a structure in which an ethoxybenzyl group with appropriate lipophilicity is conjugated to an anionic cyclic DOTA backbone, has an appropriate relaxation rate, and can be used as an anionic cyclic MRI contrast agent.

[0063] According to an embodiment of the present invention, the compound of the present invention can specifically bind to liver tissue. More specifically, the compound of the present invention can enter hepatocytes through specific transporters of hepatocytes, such as organic-anion transporting peptide, etc., to determine whether the growth of hepatocytes is normal.

[0064] The MRI contrast agent of another embodiment of the present invention contains the compound represented by the chemical formula 1.

[0065] ​According to an embodiment of the present invention, in the biological MRI image, the degree of contrast enhancement of the liver is very high compared to other organs for the MRI contrast agent. As described above, it can enter hepatocytes through specific transporters of hepatocytes, and determine whether the growth of hepatocytes is normal.

[0066] Therefore, the MRI contrast agent can be used for the diagnosis of liver diseases. More specifically, the MRI contrast agent can be used for the diagnosis of liver metastasis of cancer, hepatic cyst, liver cancer or biliary tract obstruction.

[0067] According to an embodiment of the present invention, the relaxation rate of the MRI contrast agent in a 4.7T magnetic resonance image is 5 mM -1 s -1 to 10 mM -1 s -1 .

[0068] Compared with the clinically used liver-specific MRI contrast agent with a linear structure, the MRI contrast agent of the present invention has excellent kinetic stability, which improves the in vivo stability, thereby minimizing the side effects of the MRI contrast agent caused by the leakage of gadolinium ions in the body, and can be used as a clinically liver-specific MRI contrast agent.

[0069] In particular, in the case of the MRI contrast agent containing the compound represented by Chemical Formula 1-1, it has high kinetic stability because of the alkyl chain structure of the compound, and the stability of the compound is optimized.

[0070] Hereinafter, for a detailed understanding of the present invention, taking the representative compounds of the present invention as examples, the compounds of the present invention, their preparation methods, and the MRI contrast agents containing them will be described. However, the present invention is not limited to the following examples.

[0071] 1. Synthesis of the compounds of the embodiments of the present invention

[0072] 1-1. Synthesis of Example 1 (Gd-suc)

[0073]

[0074] 1) Synthesis of dimethyl-2-bromosuccinate (1)

[0075] Method 1: Sulfuric acid (1.3 ml, 95% grade) was added to a solution of bromosuccinic acid (5 g, 25.38 mmol) dissolved in methanol (75 ml) at room temperature, while stirring. Then, the colorless reaction solution was heated and stirred at 120 °C for 1 hour under a reflux device.

[0076] After the reaction was completed, the reactants were cooled to room temperature. After removing methanol by rotary evaporation, 5% NaHCO3 solution was added to neutralize the pH of the reactants to 6, and then diethyl ether (200 ml) was added to extract the reactants. The extraction process using 5% NaHCO3 solution and diethyl ether was repeated twice, and then the organic layer containing the product was washed twice with saturated NaCl solution. After extraction and washing were completed, anhydrous MgSO4 was added to the organic layer for dehydration, and rotary evaporation was carried out to obtain a colorless oily product (1) (4.91 g, 21.83 mmol, 86%).

[0077] Method 2: Thionyl chloride (3.66 ml, 50.76 mmol) was slowly added to bromosuccinic acid (5 g, 25.38 mmol) dissolved in methanol (120 ml) and cooled to 0 °C while stirring. After the addition of thionyl chloride was completed, the reaction mixture was warmed to room temperature and stirred for 24 hours for the reaction.

[0078] After the reaction was completed, methanol was removed by rotary evaporation and neutralized with 5% NaHCO3 solution. The reactants were extracted by adding diethyl ether (200 ml) to the neutralized reactants. The extraction process using 5% NaHCO3 solution and diethyl ether was repeated twice, and then the organic layer containing the product was washed twice with saturated NaCl solution. After extraction and washing were completed, anhydrous MgSO4 was added to the organic layer for dehydration, and rotary evaporation was carried out to obtain a colorless oily product (1). The obtained oil was obtained through a silica gel column (petroleum ether / ethyl acetate) (4.63 g, 20.56 mmol, 81%).

[0079] 1 H NMR (500 MHz, CDCl3) δ 4.55 (dd, J = 8.8, 6.2 Hz, 1H), 3.78 (s,3H), 3.68 (s, 3H), 3.25 (dd, J = 17.2, 8.8 Hz, 1H), 2.96 (dd, J = 17.2, 6.2,3.3 Hz, 1H).

[0080] Of the said product (1) 1 The H NMR (500 MHz) spectrum is as Figure 1 shown.

[0081] 2) Synthesis of dimethyl 2-(4,10-bis(2-(tert-butoxy)-2-oxoethyl)-1,4,7,10-tetraazacyclododecan-1-yl)succinate (2)

[0082] A solution of dimethyl 2-bromosuccinate (1) (0.5 g, 2.22 mmol) dissolved in ACN (20 ml) was slowly added to a room temperature mixed solution of di-tert-butyl 2,2'-(1,4,7,10-tetraazacyclododecane-1,7-diyl)diacetate (0.89 g, 2.22 mmol) and NaHCO3 (1.23 g, 8.89 mmol) (ACN 100 ml), and added slowly over 2 days with stirring (syringe pump: 0.35 ml / hr). The reaction end point was confirmed by LC / MS or thin layer chromatography (silica, DCM:MeOH = 95:5).

[0083] After the reaction was completed, the solid base was filtered off, and the ACN of the reactants was removed by rotary evaporation under reduced pressure. The reactants were recrystallized from n-hexane to obtain a colorless crystalline product (2) (0.94 g, 1.73 mmol, 78%).

[0084] 1 H NMR (500 MHz, Acetone-d) δ 4.09 (dd, J = 9.5, 4.1 Hz, 1H), 3.81(s, J = 20.0 Hz, 3H), 3.65 (s, 3H), 3.54 - 3.42 (m, 4H), 3.25 - 3.11 (m, 6H),3.02 - 2.60 (m, 12H), 1.45 (s, 18H).

[0085] For the product (2) 1 The H NMR (500 MHz) spectrum is as Figure 2 shown.

[0086] 3) Synthesis of dimethyl 2-(4,10-bis(2-(tert-butoxy)-2-oxoethyl)-7-(4-ethoxybenzyl)-1,4,7,10-tetraazacyclododecane-1-yl)succinate (3)

[0087] 1-(Chloromethyl)-4-ethoxybenzene (2.69 g, 15.76 mmol) was added to a room-temperature mixed solution (100 ml of ACN) of the above-mentioned product (2) (5.17 g, 9.49 mmol) and K2CO3 (3.93 g, 28.47 mmol), and the mixture was stirred at room temperature for 18 hours. The reaction endpoint was confirmed by LC / MS or thin-layer chromatography (silica gel, DCM:MeOH = 95:5).

[0088] After the reaction was completed, the solid base was filtered off, and the ACN of the reactants was removed by rotary evaporation under reduced pressure. Diethyl ether (300 ml) was added to the reaction mixture after removing the solvent to dissolve it, and the mixture was extracted 3 times with 1M aqueous HCl solution. The by-products in the organic layer were removed, and the pH of the remaining aqueous layer was neutralized to 6 - 7 by adding 3M NaOH solution. The product precipitated as a white solid, and then DCM (300 ml) was added thereto to extract the product into the organic layer. The organic layer of the extracted product was dehydrated with anhydrous MgSO4, and rotary evaporation gave a pale yellow solid, which was purified by silica gel column (chloroform / MeOH) to obtain a white solid product (3) (5.35 g, 7.88 mmol, 83%).

[0089] 4) Synthesis of 2-(4,10-bis(carboxymethyl)-7-(4-ethoxybenzyl)-1,4,7,10-tetraazacyclododecan-1-yl)succinic acid (4)

[0090] The above-mentioned product (3) (4.68 g, 6.89 mmol) was dissolved in THF (175 ml) and 0.3M aqueous LiOH solution (175 ml), and the mixture was stirred at room temperature for 18 hours. The reaction endpoint was confirmed by LC / MS. After the reaction was completed, THF was removed by rotary evaporation under reduced pressure, and the volume of water was reduced to 10 ml. The reaction mixture was acidified with washed amberlite IR 120 (H + form) and water was removed from the reactants. Then the above-mentioned reactants were dissolved in DCM (150 ml) and trifluoroacetic acid (150 ml) and reacted for 18 hours.

[0091] After the reaction was completed, all solvents of the reaction mixture after deprotection were removed and dissolved in methanol, and purified under diethyl ether conditions to obtain a precipitate. The precipitate was dissolved in triple-distilled water containing 0.1% TFA and purified by flash chromatography (Biotage, sfar C18 30 g) or semi-preparative HPLC (YMC, Hydrosphere C18) to finally obtain the white solid product (4) (3.38 g, 6.27 mmol, 91%).

[0092] HR-FABMS: Calc. 539.2717, found. 539.2718 [M+H] + .

[0093] The HR-FABMS (positive mode) analysis results of the product (4) are as Figure 3 shown.

[0094] 5) Synthesis of gadolinium complex (Gd-suc) (5)

[0095] sodium salt: Gd2O3 (1.07 g, 2.95 mmol) was added to a solution of the above product (4) (0.317 g, 5.89 mmol) dissolved in triple-distilled water (40 ml), and stirred at 90 °C for 18 hours. The reaction end point was confirmed by LC / MS or thin layer chromatography (C18, water:ACN = 7:3).

[0096] After the reaction was completed, 1M aqueous NaOH solution was added to adjust the pH to 7, and purified by flash chromatography (Biotage, sfar C18 30 g) or semi-preparative HPLC (YMC, Hydrosphere C18) to finally obtain the white solid gadolinium complex (5).

[0097] meglumine salt: Gd2O3 (1.07 g, 2.95 mmol) was added to a solution of the above product (4) (0.317 g, 5.89 mmol) dissolved in triple-distilled water (40 ml), and stirred at 90 °C for 18 hours. The reaction end point was confirmed by LC / MS or thin layer chromatography (C18, water: ACN = 7:3).

[0098] After the reaction was completed, purification was carried out by flash chromatography (Biotage, sfar C18 30 g) or semi-preparative HPLC (YMC, Hydrosphere C18). Meglumine (5.89 mmol) was added to the purified product for salification, and the mixture was freeze-dried to obtain a white solid gadolinium complex (5) (hereinafter named Gd-suc) (3.79 g, 5.48 mmol, 93%).

[0099] HR-FABMS: Calc. 694.1723, found. 694.1720 [M+2H]+,

[0100] HR-ESIMS: Calc. 692.1537, found. 692.1578, [M] - .

[0101] The HPLC analysis results, HR-FABMS (positive mode), and HR-ESIMS (negative mode) analysis results of the Gd-suc (5) are shown respectively as Figures 4 to 6 follows.

[0102] 1-2. Synthesis of Example 2 (Gd-glu)

[0103]

[0104] 1) Synthesis of dimethyl (R)-2-bromopentanedioate (6)

[0105] At 0 °C, sodium nitrite (15.6 g, mmol) was slowly added to a reaction mixture of L-glutaric acid (15 g, mmol) and sodium bromide (26.22 g, mmol) dissolved in 2N HBr solution (125 ml) over 30 minutes. After the addition, the mixture was stirred at room temperature for 5 minutes, sulfuric acid (95%, 5 ml) was added to the reaction mixture stirred at room temperature, and the mixture was stirred at room temperature for 1.5 hours.

[0106] Diethyl ether (200 ml) was added to the reaction mixture after the reaction was completed, and the process of extracting the product with the organic layer was repeated three times. The extracted organic layer was dehydrated with anhydrous MgSO4, and the solvent was removed by rotary evaporation to obtain a yellow oil. The yellow oil was dissolved in MeOH (65 ml) and SOCl2 (4 ml) was added, and the reaction was carried out at room temperature for 2 days.

[0107] After the reaction was completed, the excess SOCl2 was neutralized with 5% NaHCO solution and extracted with DCM (150 ml). The extracted organic layer was dehydrated with anhydrous MgSO4 and rotary evaporated under reduced pressure to obtain a bright yellow oil. The above bright yellow oil was purified using a silica gel column (petroleum ether / ethyl acetate) to obtain a colorless oily product (6) (5.29 g, 0.022 mmol, 21.57%).

[0108] 1 1H NMR (500 MHz, CDCl3) δ 4.43 - 4.34 (m, J = 8.5, 5.8 Hz, 1H), 3.79(s, 3H), 3.70 (s, 3H), 2.60 - 2.46 (m, 2H), 2.44 - 2.25 (m, 2H).

[0109] The 1 1H NMR (500 MHz) spectrum of the product (6) is as Figure 7 shown.

[0110] 2) Synthesis of dimethyl (R)-2-(4,10-bis(2-(tert-butoxy)-2-oxoethyl)-1,4,7,10-tetraazacyclododecan-1-yl)pentanedioate (7)

[0111] A solution of dimethyl (R)-2-bromopentanedioate (6) (5.1 g, 21.33 mmol) dissolved in ACN (100 ml) was slowly added dropwise over 2 days to a room temperature mixture of bis(tert-butyl) 2,2'-(1,4,7,10-tetraazacyclododecane-1,7-diyl)diacetate (8.55 g, 21.33 mmol) and K2CO3 (2.95 g, 21.33 mmol) in ACN (100 ml) with stirring (syringe pump: 5 ml / hr). The reaction endpoint was confirmed by LC / MS or thin layer chromatography (silica, DCM:MeOH = 95:5).

[0112] After the reaction was completed, the solid base was filtered off and the ACN of the reactants was removed by rotary evaporation under reduced pressure to obtain a bright yellow oil. The above bright yellow oil was purified using a silica gel column (CHCl3 / MeOH) and precipitated in diethyl ether to obtain a white solid product (7) (9.17 g, 16.44 mmol, 56%).

[0113] 11H NMR (500 MHz, CDCl3) δ 3.73 - 3.62 (m, 6H), 3.49 (dt, J = 15.4, 7.7Hz, 1H), 3.40 - 3.16 (m, 4H), 3.04 - 2.45 (m, 17H), 2.30 - 2.24 (m, J = 13.1Hz, 2H), 2.07 - 1.87 (m, 2H), 1.51 - 1.40 (m, 18H).

[0114] For the product (7) 1 The 1H NMR (500 MHz) spectrum is as Figure 8 shown.

[0115] 3) Synthesis of dimethyl (S)-2-(4,10-bis(2-(tert-butoxy)-2-oxoethyl)-7-(4-ethoxybenzyl)-1,4,7,10-tetraazacyclododecan-1-yl)pentanedioate (8)

[0116] 1-(Chloromethyl)-4-ethoxybenzene (0.93 g, 5.34 mmol) was added to a room temperature mixed solution (60 ml of ACN) of the above product (7) (1.99 g, 3.56 mmol) and K2CO3 (1.48 g, 10.69 mmol), and the mixture was stirred at room temperature for 18 hours. The reaction end point was confirmed by LC / MS or thin layer chromatography (silica gel, DCM:MeOH = 95:5).

[0117] After the reaction was completed, the solid base was filtered off, and ACN was removed by rotary evaporation under reduced pressure. Diethyl ether (100 ml) was added to the reaction mixture from which the solvent had been removed to dissolve it, and the mixture was extracted 3 times with 1 M aqueous HCl solution. The by-products in the organic layer were removed, and the pH of the remaining aqueous layer was neutralized to 6 - 7 by adding 3 M NaOH solution. The product precipitated as a white solid, and DCM (100 ml) was added thereto to extract the product into the organic layer. The organic layer of the extracted product was dehydrated with anhydrous MgSO4 and rotary evaporated to obtain a pale yellow solid, which was purified by silica gel column (chloroform / MeOH) to obtain a white solid product (8) (0.70 g, 1.01 mmol, 28.37%).

[0118] 4) Synthesis of (S)-2-(4,10-bis(carboxymethyl)-7-(4-ethoxybenzyl)-1,4,7,10-tetraazacyclododecan-1-yl)pentanedioic acid (9)

[0119] Dissolve the above product (8) (0.7 g, 1.01 mmol) in 5 M aqueous NaOH (4.4 ml) and MeOH (4.4 ml), and stir at room temperature for 18 hours. Confirm the reaction endpoint by LC / MS. After the reaction is completed, remove MeOH by rotary evaporation under reduced pressure and reduce the volume of water to 2 ml.

[0120] Acidify the reaction mixture with washed amberlite IR 120 (H + form) and remove water from the reactants. Then dissolve the above reactants in DCM (50 ml) and trifluoroacetic acid (50 ml) and react for 18 hours.

[0121] After the reaction is completed, remove all solvents from the reaction mixture after deprotection and dissolve in methanol. Purify under diethyl ether conditions to obtain a precipitate. Dissolve the precipitate in triple-distilled water containing 0.1% TFA and purify by flash chromatography (Biotage, sfar C18 30 g) or semi-preparative HPLC (YMC, Hydrosphere C18) to finally obtain a white solid product (9) (0.24 g, 0.43 mmol, 43%).

[0122] HR-ESIMS: Calc. 553.2874, found. 553.2877, [M+H] + .

[0123] The HR-ESIMS (positive mode) analysis result of the product (9) is as Figure 9 shown.

[0124] 5) Synthesis of gadolinium complex (Gd-glu) (10)

[0125] sodium salt: Add Gd2O3 (0.295 g, 0.453 mmol) to a solution of the above product (9) (0.5 g, 0.905 mmol) dissolved in triple-distilled water (15 ml), and stir at 90 °C for 18 hours. Confirm the reaction endpoint by LC / MS or thin-layer chromatography (C18, water:ACN = 7:3).

[0126] After the reaction is completed, add 1 M aqueous NaOH to adjust the pH to 7, and purify by flash chromatography (Biotage, sfar C18 30 g) or semi-preparative HPLC (YMC, Hydrosphere C18) to finally obtain a white solid gadolinium complex (10).

[0127] Meglumine salt: Gd2O3 (0.295 g, 0.453 mmol) was added to a solution of the above product (9) (0.5 g, 0.905 mmol) dissolved in tertiary distilled water (15 ml), and the mixture was stirred at 90 °C for 18 hours. The reaction end point was confirmed by LC / MS or thin layer chromatography (C18, water:ACN = 7:3).

[0128] After the reaction, purification was carried out by flash chromatography (Biotage, sfar C18 30 g) or semi-preparative HPLC (YMC, Hydrosphere C18). Meglumine (0.905 mmol) was added to the purified product for salification, and the product was freeze-dried to obtain a white solid gadolinium complex (10) (hereinafter named Gd-glu) (0.44 g, 0.62 mmol, 69%).

[0129] HR-ESIMS: Calc. 706.1723, found. 706.1734, [M] - .

[0130] The analysis results of HR-ESIMS (positive mode) of the said Gd-glu (10) are as Figure 10 shown.

[0131] 2. MRI contrast effect

[0132] In order to investigate the MRI contrast effects of the compounds (Gd-suc, Gd-glu) of the embodiments of the present invention and commercially available MRI contrast agents, the relaxation rate and lipophilicity were analyzed, and the results are shown in Table 1.

[0133] Table 1

[0134] <![CDATA[r1]]> <![CDATA[r2]]> <![CDATA[r2 / r1]]> Log P Gd-suc 5.96±0.014 5.59±0.74 0.94 -2.50±004 Gd-glu 8.41±0.084 9.92±0.081 1.18 - Primovist 6.51±0.040 7.31±0.42 1.12 -2.91±058 Multihance 5.09±0.015 6.79±0.38 1.33 -2.90±038 dotarem 4.19±0.014 4.75±0.016 1.34 - Gadovist 4.12±0.028 4.60±0.025 1.12 - ProHance 3.58±0.017 4.58±0.071 1.28 - Omniscan 3.58±0.014 4.46±0.024 1.25 - magnevist 3.57±0.007 4.95±0.18 1.39 -

[0135] Relaxation rate (mM -1 s -1 ) is a parameter representing the contrast efficiency per unit concentration. It is known that in the case of T1 contrast agents, the r2 / r1 ratio is 0.5 - 1.5.

[0136] Referring to Table 1, in the case of the compound Gd-suc of the present invention, compared with the clinical MRI contrast agent used as an extracellular fluid preparation, it has higher levels of r2 and r1 values, and has relaxation rate and lipophilicity similar to those of the clinical MRI contrast agents (Primovist, Multihance) used as liver-specific reagents.

[0137] 3. Kinetic stability evaluation

[0138] MRI contrast agents using gadolinium complexes may have structural instability due to the interaction between the ligand structure and ions in the body. Therefore, to evaluate the kinetic stability of the compounds (Gd-suc, Gd-glu) of the embodiments of the present invention and commercially available MRI contrast agents, the change in relaxation rate over time was measured, and the results are as Figure 11 shown.

[0139] Specifically, after adding zinc chloride (1 eq. ZnCl2) to solutions (room temperature, 2.5 mM, PBS) separately dissolved with Gd-suc, Gd-glu, and a commercially available MRI contrast agent, a metal exchange reaction between gadolinium and zinc ions was induced under the in vivo pH environment (pH 7.4), and its relaxation rate (3T MRI, GE Healthcare, Architect) was measured and confirmed.

[0140] As Figure 11 shown, the compound Gd-suc of the present invention shows significantly higher kinetic stability compared to commercially available liver-specific contrast agents Primovist and Multihance, which is similar to the value of Dotarem as Gd-DOTA.

[0141] 4. In vivo MRI contrast effect

[0142] The liver-specific T1 contrast effect of the compounds (Gd-suc, Gd-glu) of the embodiments of the present invention and the commercially available liver contrast agent Primovist was confirmed through abdominal T1-weighted enhanced images (Bruker, 4.7 T) of small animals (Balb / C mice, male, 5w, 25g, 0.1 mmol / kg), and the results are as Figures 12 to 15 shown.

[0143] See Figure 12 It can be seen that the compound Gd-suc of the present invention showed rapid hepatobiliary system contrast enhancement and excretion within 15 minutes after intravenous administration to the tail vein of mice. This is one of the characteristics of liver-specific contrast agents and can be confirmed as the contrast enhancement phenomenon of the gall bladder.

[0144] Moreover, the degree of liver-specific contrast enhancement of Gd-suc showed a level similar to that of the commercially available liver-specific MRI contrast agent Primovist (see Figure 13 ).

[0145] On the other hand, see Figure 14 It can be seen that the compound Gd-glu of the present invention also has a contrast enhancement effect on the gall bladder, so it can be used as a liver disease-specific MRI contrast agent.

[0146] And, referring to Figure 15 it can be seen that Gd-suc shows a very strong liver contrast enhancement phenomenon in in vivo MRI images within 5 minutes, which makes rapid clinical abdominal MRI imaging possible.

[0147] 5. In vitro cell-viability experiment

[0148] To confirm the presence or absence of cytotoxicity in normal hepatocytes, the AML12 cell line was used, and the compound Gd-suc of the embodiment of the present invention and commercially available liver contrast agents Primovist and Multihance were treated at different concentrations. After 24 hours, cell viability was analyzed by the known CCK method, and the results are as Figure 16 shown.

[0149] Referring to Figure 16 it can be seen that the compound Gd-suc of the present invention has a cell viability of more than 95% at a concentration of 400 μM and does not show cytotoxicity, while the commercially available liver contrast agents Primovist and Multihance have a cell viability of 80% or less at concentrations of 400 μl and 200 μM or more, respectively, showing significant cytotoxicity.

[0150] It should be understood that the above has been described in conjunction with the preferred embodiments of the present invention, but those of ordinary skill in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention.

Claims

1. An anionic compound, characterized in that, represented by the following Chemical Formula 1, Chemical Formula 1: in the said Chemical Formula 1, R represents -COO - , -CH2COO - or -CH2CH2COO - .

2. The anionic compound according to claim 1, characterized in that, the said Chemical Formula 1 is represented by the following Chemical Formula 1-1, Chemical Formula 1-1:

3. The anionic compound according to claim 1, characterized in that, the said Chemical Formula 1 is represented by the following Chemical Formula 1-2, Chemical Formula 1-2:

4. The anionic compound according to claim 1, characterized in that, the said Chemical Formula 1 is represented by the following Chemical Formula 1-3, Chemical Formula 1-3:

5. An MRI contrast agent, characterized in that ， comprising the anionic compound according to Claim 1.

6. The MRI contrast agent according to Claim 5, characterized in that, The relaxation rate of the MRI contrast agent in 4.7T magnetic resonance images is 5 mM -1 s -1 to 10 mM -1 s -1 .

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