Novel gadolinium-based compound, preparation method thereof and MRI contrast agent containing same

Abstract

The present invention relates to a novel gadolinium-based compound having a structure in which a gadolinium complex and gallic acid are connected via a connecting group, a preparation method thereof and an MRI contrast agent containing the same.

Description

Technical Field

[0001] The present invention relates to a novel gadolinium-based compound, a preparation method thereof, and an MRI contrast agent containing the same. Specifically, the present invention relates to a novel gadolinium-based compound having a structure in which a gadolinium complex and gallic acid are linked via a linking group, a preparation method thereof, and an MRI contrast agent containing the same. Background Art

[0002] Nowadays, due to the aging of the population, the number of patients suffering from degenerative brain diseases is increasing, and therefore, early detection of diseases is urgently needed. Degenerative brain diseases include Parkinson's disease, vascular dementia, Alzheimer's disease, etc., and one of the causes of these diseases is neurotoxicity caused by excessive accumulation of amyloid β polymers (oligomeric Aβ).

[0003] Amyloid β (Aβ) is the main component of amyloid plaques found in the brains of Alzheimer's patients. It refers to a 36 to 43 amino acid peptide that plays a decisive role in Alzheimer's disease. This peptide is derived from the amyloid precursor protein (APP).

[0004] Amyloid β molecules can aggregate to form soluble polymers that can exist in various forms, and it is well known that the formed amyloid β polymers (oligomeric Aβ) are toxic to nerve cells, and therefore, when excessively accumulated in the brain, are directly involved in the onset of Alzheimer's disease. It is therefore expected that by detecting changes in the concentration of amyloid β polymers, early diagnosis of degenerative brain diseases will be possible.

[0005] On the other hand, magnetic resonance imaging (MRI) is a method of obtaining anatomical, physiological, and biochemical information images of the body by utilizing the phenomenon of hydrogen atom relaxation in a magnetic field and the different distribution of hydrogen atoms between body tissues. Unlike CT or PET, MRI does not use radiation that is harmful to the human body, but uses magnetic field gradients and radio waves under a strong magnetic field to produce images in the body, so it is non-invasive, has high resolution, and is very suitable for soft tissue examinations.

[0006] In order to use MRI equipment more precisely, contrast agents are injected into the subject to obtain MRI images. The contrast between tissues on the MRI image is caused by the different relaxation effects of the nuclear spins of water molecules in the tissues returning to the equilibrium state. Contrast agents use paramagnetic or superparamagnetic materials to affect the relaxation effect, thereby increasing the difference in relaxation between tissues, causing changes in MRI signals, and playing a role in making the contrast between tissues clearer.

[0007] At present, the most commonly used contrast agent in clinical practice is a contrast agent based on gadolinium (Gd) chelate. Currently, Gd-DTPA (Magnevist), Gd-DOTA (Dotaram), Gd (DTPA-BMA) (Omniscan), Gd (DO3A-HP) (ProHance), Gd (BOPTA) (MultiHance) etc. are used. However, most commercially available contrast agents are non-specific contrast agents distributed in the extracellular space (extracellular fluide, ECF). As a specific contrast agent, only liver-specific contrast agents are used in particular. Although recent studies have promoted the development of contrast agents that can show signal enhancement by having specific targeting or physiological activity (pH changes, enzyme activity), sufficient results have not yet been obtained for specific MRI contrast agents for degenerative encephalopathy. Summary of the invention

[0008] The object of the present invention is to provide a gadolinium-based compound, which can be used as an MRI contrast material, and in particular, has specificity for degenerative brain diseases.

[0009] Another object of the present invention is to provide an MRI contrast agent containing the compound.

[0010] Another object of the present invention is to provide a method for preparing the compound.

[0011] According to the present invention, a gadolinium-based compound is provided, wherein it is represented by the following Chemical Formula 1.

[0012] [Chemical formula 1]

[0013]

[0014] In the chemical formula 1,

[0015] A represents *-(CH2) n -A 1 -*,

[0016] n represents any integer from 0 to 5,

[0017] A 1 represents *-COO-*, *-CO-*, *-NH-*, *-CH2-*, *-CONH-* or *-O-*,

[0018] Linking group indicates *-L 1 -NHCO-L 2 -*, *-L 1 -OROL 2 -*, *-L 1 -CH2-L 2 -*, *-L 1 -NH-L 2 -*, or *-L 1 -COO-L 2 -*,

[0019] L 1 represents a straight chain or branched (C1-C30) alkylene group,

[0020] L 2 represents a single bond, or a straight or branched (C1-C30) alkylene group,

[0021] R represents a linear or branched (C1-C20) alkylene group,

[0022] Ga represents chemical formula 2:

[0023] [Chemical formula 2]

[0024]

[0025] * indicates the attachment site.

[0026] Furthermore, according to the present invention, an MRI contrast agent is provided, which contains the gadolinium-based compound represented by the Chemical Formula 1.

[0027] Moreover, according to one embodiment of the present invention, there is provided a method for preparing the gadolinium-based compound represented by the chemical formula 1, comprising the following steps, wherein:

[0028] (a) reacting a compound of the following Chemical Formula 1-1 with a halogen compound to obtain a compound of the following Chemical Formula 1-2;

[0029] [Chemical formula 1-1]

[0030]

[0031] [Chemical formula 1-2]

[0032]

[0033] In the chemical formulas 1-1 and 1-2,

[0034] PT 1 represents a protecting group,

[0035] X represents a halogen atom,

[0036] L 2 As defined in Chemical Formula 1,

[0037] (b) reacting the compound of Chemical Formula 1-2 with the compound of the following Chemical Formula 1-3 to obtain the compound of the following Chemical Formula 1-4;

[0038] [Chemical formula 1-3]

[0039]

[0040] [Chemical formula 1-4]

[0041]

[0042] In the chemical formulas 1-3 and 1-4,

[0043] PT 1 and PT 2 Each independently represents a protecting group,

[0044] Linking group indicates *-L 1 -NH-L 2 -*,

[0045] L 1 , L 2 and A is as defined in the above chemical formula 1,

[0046] (c) removing PT from the compound of Chemical Formula 1-4 1 and PT 2 steps; and

[0047] (d) a step of reacting the compound obtained in step (c) with gadolinium hydrate to obtain a compound of Chemical Formula 1.

[0048] Moreover, according to other embodiments of the present invention, a method for preparing the gadolinium-based compound represented by the chemical formula 1 is provided, comprising the following steps, wherein:

[0049] (a) reacting a compound of the following Chemical Formula 2-1 with a compound of the following Chemical Formula 2-2 to obtain a compound of the following Chemical Formula 2-3;

[0050] [Chemical formula 2-1]

[0051]

[0052] [Chemical formula 2-2]

[0053]

[0054] [Chemical formula 2-3]

[0055]

[0056] In the chemical formulas 2-1 to 2-3,

[0057] PT 3 represents a protecting group,

[0058] Linking group indicates *-L 1 -NH-L 2 -*,

[0059] L 1 , L 2 and A is as defined in the above chemical formula 1,

[0060] (b) Removing PT from the compound of Chemical Formula 2-3 3 steps; and

[0061] (c) a step of reacting the compound obtained in step (b) with gadolinium hydrate to obtain a compound of Chemical Formula 1.

[0062] Effects of the Invention

[0063] The novel gadolinium-based compound according to the present invention can be used not only as an MRI contrast material due to its sufficient self-relaxation property, but also can be combined with β-amyloid protein polymer (oligomeric Aβ) to obtain an MRI contrast enhancement effect in the presence of β-amyloid protein polymer, thereby being used for the diagnosis of diseases related to β-amyloid protein polymer, especially the diagnosis of degenerative brain diseases. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1a is the compound 6 prepared in Example 1 of the compound according to the present invention 1 H NMR spectrum.

[0065] Figure 1b is the HR-ESI-MS spectrum of compound 6 prepared in Example 1 of the compound according to the present invention.

[0066] Figure 2a HR-ESI-MS spectrum of Gd-DO3A-Ga prepared in Example 1 of the compound according to the present invention.

[0067] Figure 2b HPLC chromatogram of Gd-DO3A-Ga prepared in Example 1 of the compound according to the present invention.

[0068] Figure 3a is the compound 4 prepared in Example 2 of the compound according to the present invention 1 H NMR spectrum.

[0069] Figure 3b is the compound 4 prepared in Example 2 of the compound according to the present invention 13 C NMR spectrum.

[0070] Figure 3c is the HR-MS spectrum of compound 4 prepared in Example 2 of the compound according to the present invention.

[0071] Figure 4a HR-MS spectrum of Gd-DO3A-Ga prepared in Example 2 of the compound according to the present invention.

[0072] Figure 4b HPLC chromatogram of Gd-DO3A-Ga prepared in Example 2 of the compound according to the present invention.

[0073] Figure 5 A graph showing the self-relaxation rate (r1, r2) analysis of Gd-DO3A-Ga according to the present invention.

[0074] Figure 6 A graph showing the kinetic stability of Gd-DO3A-Ga according to the present invention and various commercially available contrast agents (Gadovist, Dotarem, Prohance, Magnevist, Primovist, Multihance).

[0075] Figure 7 It is a comparison graph showing the MR signal intensity of MRI specimens. DETAILED DESCRIPTION

[0076] Below, the terms used in this application are only used to illustrate specific embodiments and are not intended to limit the present invention. Unless otherwise defined, all terms used in this specification, including technical or scientific terms, have the same meanings as those commonly understood by those of ordinary skill in the art to which the present invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as meanings consistent with those in the context of the relevant technology and should not be interpreted as ideal or overly formalized meanings unless clearly defined in this application.

[0077] The gadolinium-based compound according to the present invention can be represented by the following Chemical Formula 1.

[0078] [Chemical formula 1]

[0079]

[0080] In the chemical formula 1,

[0081] A represents *-(CH2) n -A 1 -*,

[0082] n represents any integer from 0 to 5, specifically, it can represent any integer from 1 to 5, more specifically, it can be any integer from 1 to 3,

[0083] A 1 represents *-COO-*, *-CO-*, *-NH-*, *-CH2-*, *-CONH-*, or *-O-*, and specifically, may represent *-CONH-*,

[0084] Linking group indicates *-L 1 -NHCO-L 2 -*, *-L 1 -OROL 2 -*, *-L 1 -CH2-L 2 -*, *-L 1 -NH-L 2 -*, or *-L 1 -COO-L 2 -*, specifically, can represent *-L 1 -NH-L 2 -*,

[0085] L 1 represents a linear or branched (C1-C30) alkylene group, specifically, L 1 It may be a linear or branched (C1-C10) alkylene group, more specifically, it may be a linear or branched (C1-C5) alkylene group,

[0086] L 2 represents a single bond, or a linear or branched (C1-C30) alkylene group, specifically, it can be a single bond, R represents a linear or branched (C1-C20) alkylene group, specifically, it can represent a linear or branched (C1-C10) alkylene group, more specifically, it can represent a linear or branched (C1-C5) alkylene group, and Ga represents Chemical Formula 2:

[0087] [Chemical formula 2]

[0088]

[0089] * indicates the attachment site.

[0090] According to an implementation example of the present invention, in the chemical formula 1, n can represent any integer from 1 to 5, A 1 It can represent *-CONH-*.

[0091] According to other implementation examples of the present invention, L 1 It can represent a straight chain or branched (C1-C10) alkylene group, L 2 Can represent a single bond.

[0092] In the gadolinium-based compound of the Chemical Formula 1, gadolinium may be coordinated with at least one water molecule. For example, in the gadolinium-based compound of the Chemical Formula 1, gadolinium may be coordinated with one or two water molecules.

[0093] In the gadolinium-based compound of Chemical Formula 1 of the present invention, when A 1 In the case of *-COO-*, *-CO-*, or *-CONH-*, the oxygen atom can form a coordinate bond with gadolinium.

[0094] Chemical formula 2 of the present invention is a part derived from gallic acid. Gallic acid is a polyphenol compound, a chemical substance found in plants, containing two or more phenolic groups in one molecule, and has been used as a main component of anti-aging agents and disease treatment agents due to its antioxidant effect. Until now, the use of MRI contrast agents with oligomeric Aβ targeting function has not been considered.

[0095] As shown in the examples described below, the gadolinium-based compound of Chemical Formula 1 of the present invention can specifically bind to oligomeric Aβ in mammals.

[0096] In addition, since the compound of the present invention is water-soluble and has self-relaxation properties by coordinating with at least one water molecule, it can improve image contrast by increasing the relaxation rate of at least one water molecule and hydrogen atom in the body, and thus can be used as an MRI contrast material.

[0097] Therefore, according to the present invention, an MRI contrast agent is provided, which contains a gadolinium-based compound represented by the chemical formula 1. In addition, since the compound of the present invention can bind to the β-amyloid protein polymer (oligomeric Aβ), the MRI contrast agent of the present invention can be specifically used for diseases related to the β-amyloid protein polymer (oligomeric Aβ), and more specifically, can be used to diagnose degenerative brain diseases, such as Parkinson's disease, vascular dementia, Alzheimer's disease, and other degenerative diseases. Therefore, according to an implementation example of the present invention, a specific MRI contrast agent for diagnosing degenerative brain diseases can be provided, which contains the compound of the chemical formula 1. Furthermore, as described above, according to the latest research, it is confirmed that the amyloid β polymer (oligomeric Aβ) induced by the amyloid precursor protein is excessively accumulated in the brain and is involved in the onset of Alzheimer's disease. Therefore, the MRI contrast agent containing the compound of the present invention targeting the β-amyloid protein polymer can become a specific MRI contrast agent for early diagnosis of Alzheimer's disease.

[0098] According to one embodiment of the present invention, the gadolinium-based compound of Chemical Formula 1 can be prepared by a method comprising the following steps:

[0099] (a) reacting a compound of the following Chemical Formula 1-1 with a halogen compound to obtain a compound of the following Chemical Formula 1-2;

[0100] (b) reacting a compound of the following Chemical Formula 1-2 with a compound of the following Chemical Formula 1-3 to obtain a compound of the following Chemical Formula 1-4;

[0101] (c) removing PT from the compound of Chemical Formula 1-4 1 and PT 2 steps; and

[0102] (d) a step of reacting the compound obtained in step (c) with gadolinium hydrate to obtain a compound of Chemical Formula 1.

[0103] [Chemical formula 1-1]

[0104]

[0105] [Chemical formula 1-2]

[0106]

[0107] In the chemical formulas 1-1 and 1-2,

[0108] PT 1 represents a protecting group,

[0109] X represents a halogen atom,

[0110] L 2 As defined in the above chemical formula 1.

[0111] [Chemical formula 1-3]

[0112]

[0113] [Chemical formula 1-4]

[0114]

[0115] In the chemical formulas 1-3 and 1-4,

[0116] PT 1 and PT 2 Each independently represents a protecting group,

[0117] Linking group indicates *-L 1 -NH-L 2 -*,

[0118] L 1 , L 2 and A is as defined in Chemical Formula 1 above.

[0119] According to an implementation example of the present invention, in step (a), the L 2 may be a single bond, and the halogen compound may be thionyl chloride.

[0120] In the chemical formulas 1-1, 1-2 and 1-4, PT 1 represents a protecting group, and is generally used for protecting a -OH group, for example, acetyl, benzoyl, methoxymethyl ether, methylthiomethyl ether and the like.

[0121] In the chemical formulas 1-3 and 1-4, PT 2 represents a protecting group, and is generally used for protecting a -COOH group, for example, a methyl group, a benzyl group, a tert-butyl group, etc. are mentioned.

[0122] The step (c) is a step of removing the protecting group, wherein the protecting group, i.e., PT 1 and PT 2 The removal can be carried out by a commonly used method in the art, for example, an aqueous alkali solution or an aqueous acid solution can be used.

[0123] According to another embodiment of the present invention, a method for preparing a gadolinium-based compound represented by Chemical Formula 1 is provided, comprising the following steps:

[0124] (a) reacting a compound of the following Chemical Formula 2-1 with a compound of the following Chemical Formula 2-2 to obtain a compound of the following Chemical Formula 2-3;

[0125] (b) Removing PT from the compound of Chemical Formula 2-3 3 steps; and

[0126] (c) a step of reacting the compound obtained in step (b) with gadolinium hydrate to obtain a compound of Chemical Formula 1.

[0127] [Chemical formula 2-1]

[0128]

[0129] [Chemical formula 2-2]

[0130]

[0131] [Chemical formula 2-3]

[0132]

[0133] In the chemical formulas 2-1 to 2-3,

[0134] PT 3 represents a protecting group,

[0135] Linking group indicates *-L 1 -NH-L 2 -*,

[0136] L 1 , L 2 and A are as defined in Chemical Formula 1 above.

[0137] According to an implementation example of the present invention, in step (a), the L 2 It may be a single bond. That is, the compound of Chemical Formula 2-1 may be gallic acid.

[0138] In the chemical formulas 2-2 and 2-3, PT 3 represents a protecting group, and is generally used for protecting a -COOH group, for example, a methyl group, a benzyl group, a tert-butyl group, etc. are mentioned.

[0139] The step (b) is a step of removing the protecting group, wherein the protecting group, i.e., PT 3 The removal can be carried out by a commonly used method in the art, for example, an aqueous alkali solution or an aqueous acid solution can be used.

[0140] In order to understand the present invention in detail, representative compounds of the present invention are exemplified below to explain the compounds according to the present invention, the preparation methods thereof, and the characteristics of MRI contrast agents containing the compounds.

[0141] 1. Preparation Examples of Compounds According to the Present Invention

[0142] [Example 1]

[0143]

[0144] 1) Preparation of 3,4,5-triacetoxybenzoic acid (Compound 1)

[0145] Add acetic anhydride (11.34 mL, 120 mmol) to gallic acid (3.76 g, 20 mmol) to dissolve. Add a small amount of 95% concentrated sulfuric acid and stir for 1 hour until the solution becomes transparent. Then, add distilled water (100 mL) and stir for 2.5 hours to remove the residual acetic anhydride. Filter the product to obtain a solid, wash it with distilled water (3×100 mL) and dry it to obtain a white solid material (Compound 1). (Yield: 5.92 g (100%))

[0146] 2) Synthesis of 5-(Chlorocarbonyl)benzene-1,2,3-triyl triacetate (Compound 2)

[0147] Thionyl chloride (1.76 mL, 20 mmol) was dissolved in dimethylformamide (DMF) (200 μl), and then the compound 1 (2.96 g, 10 mmol) was slowly added to the solution dissolved in dichloromethane (25 mL). The reactant was stirred at 60° C. for 6 hours, and then the solvent was removed by vacuum filtration, toluene was added, and the vacuum filtration was repeated 3 times to obtain a white solid (compound 2). No further purification was performed.

[0148] 3) tri-tert-butyl 2,2',2''-(10-(2-ethoxy-2-oxoethyl)-1,4,5,10-tetraazacyclododecane- Synthesis of 1,4,7-trimethylol) triacetate (Compound 3)

[0149] After dissolving tri-tert-butyl 2,2',2''-(1,4,7,10-tetraazacyclododecane-1,4,7-triyl) triacetate (5 g, 9.72 mmol) in acetonitrile (160 mL), add potassium bicarbonate (2.96 g, 29.69 mmol) and stir for 30 minutes. Then, add ethyl bromoacetate (1.18 mL, 10.69 mmol) and stir at 60°C for 24 hours. After stirring, filter the product with a filter and remove the solvent by vacuum filtration. Dissolve the product in dichloromethane, remove insoluble matter, remove all solvents, and vacuum dry to obtain a yellow solid substance (Compound 3). (Yield: 5.8 g (99%))

[0150] 4) tri-tert-butyl 2,2',2''-(10-(2-((2-aminoethyl)amino)-2-oxoethyl)-1,4,7,10-tetrazolyl Synthesis of heterocyclododecane-1,4,7-triyl) triacetate (Compound 4)

[0151] The obtained compound 3 (3.2 g, 5.33 mmol) was dissolved in methanol (7 mL), and ethylenediamine (6 mL) was added and reacted at room temperature for 4 days. Then, the solvent was removed by heating to 55°C under vacuum to obtain an oily solid, which was washed several times with ether. After vacuum drying, the material insoluble in methanol was filtered out, and then the yellow solid (compound 4) was separated and purified by open column chromatography under dichloromethane / methanol conditions. (Yield: 1.87 g (57%))

[0152] 5) tri-tert-butyl 2,2',2''-(10-(2-oxo-2-((2-(3,4,5-triacetoxybenzamide)ethyl) Synthesis of (amino)ethyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetate (Compound 5)

[0153] The compound 4 (0.4 g, 1.27 mmol) was dissolved in acetonitrile, potassium carbonate (0.053 g, 3.81 mmol) was added and reacted for 30 minutes, and then compound 2 was added and stirred at room temperature for 20 hours. Then, after removing the solid with a filter, the solvent was removed by vacuum filtration, and separation and purification was performed by high performance liquid chromatography under distilled water / acetonitrile with 0.1% trifluoroacetic acid to obtain a yellow solid substance (compound 5).

[0154] 6) 2,2`,2``-(10-(2-oxo-2((2-(3,4,5-trihydroxybenzamide)ethyl)amino)ethyl)-1, Synthesis of 4,7,10-tetraazacyclododecane-1,4,7-triyl) triacetate (Compound 6)

[0155] Trifluoroacetic acid (2 mL) was added to compound 5 (0.65 g, 0.73 mmol) at -4°C, stirred for 20 hours, and then dichloromethane was added. The vacuum filtration process was repeated 3 times. The product was dissolved in acetone (45 mL), 3M HCl (10.5 mL) was added, and heated and stirred at 70°C for 6 hours. Then, the product was separated and purified by high performance liquid chromatography under the conditions of distilled water / acetonitrile with 0.1% trifluoroacetic acid to obtain a brown solid (compound 6). (Yield: 0.25 g (71%)). The obtained compound 6 1 H NMR spectrum and HR-ESI-MS spectrum are shown in Figure 1a and 1b .

[0156] 1 H NMR (Methanol-d4); δ = 2.96-3.25 (m, 16H, CH2 in the cyclen ring), 3.25-3.39 (m, 4H, CH2), 3.47-3.95 (m, 8H, CH2), 6.67-6.73 (m, 2H, ArH)

[0157] HR-ESI-MS(m / z):[M+H] + calculated for C 25 H 39 N6O 11,599.2677;found,599.26807)

[0158] 7) Synthesis of compound Gd-DO3A-Ga (compound of the present invention)

[0159] Compound 6 (0.31 g, 0.518 mmol) was dissolved in distilled water, the pH was adjusted to 3 with 1 M sodium hydroxide, and then Gd(Cl)3·6H2O (0.17 g, 0.47 mmol) dissolved in distilled water (500 μl) was added. After adjusting the pH to 7 with 1 M sodium hydroxide, the mixture was stirred at room temperature for 20 hours. After the stirring was completed, the solid obtained by vacuum filtration was separated and purified by high performance liquid chromatography under distilled water / acetonitrile conditions to obtain a brown solid substance (compound Gd-DO3A-Ga). The HR-ESI-MS spectrum and HPLC chromatogram of the obtained compound Gd-DO3A-Ga are shown in Figure 2a and 2b .

[0160] Yield: 0.13 g (33%)

[0161] HR-ESI-MS(m / z):[M+H] + calculated for C 25 H 35 GdN6O 11 ,754.1683;found,754.1679,

[0162] Purity analysis using analytical HPLC: 96%

[0163] [Example 2]

[0164]

[0165] 1) Tri-tert-butyl 2,2',2''-(10-(2-ethoxy-2-oxoethyl)-1,4,5,10-tetraazacyclododecane- Synthesis of 1,4,7-trimethylol) triacetate (Compound 1)

[0166] After dissolving tri-tert-butyl 2,2',2''-(1,4,7,10-tetraazacyclododecane-1,4,7-triyl) triacetate (5 g, 9.72 mmol) in acetonitrile (160 mL), add potassium bicarbonate (2.96 g, 29.69 mmol) and stir for 30 minutes. Then, add ethyl bromoacetate (1.18 mL, 10.69 mmol) and stir at 60°C for 24 hours. After 24 hours, filter the product with a filter and remove the solvent by vacuum filtration. Dissolve the product in dichloromethane, remove the insoluble matter, remove all the solvent, and vacuum dry to obtain a yellow solid substance (Compound 1). (Yield: 5.8 g (99%))

[0167] 2) tri-tert-butyl 2,2',2''-(10-(2-((2-aminoethyl)amino)-2-oxoethyl)-1,4,7,10-tetrazolyl Synthesis of heterocyclododecane-1,4,7-triyl) triacetate (Compound 2)

[0168] The obtained compound 1 (3.2 g, 5.33 mmol) was dissolved in methanol (7 mL), ethylenediamine (6 mL) was added, and the mixture was reacted at room temperature for 4 days. Then, the solvent was removed by heating to 55°C under vacuum to obtain an oily solid, which was washed several times with ether. After vacuum drying, the insoluble substances in methanol were removed by filtration, and then the yellow solid (compound 2) was separated and purified by open column chromatography under dichloromethane / methanol conditions. (Yield: 1.87 g (57%))

[0169] 3) tri-tert-butyl 2,2',2''-(10-(2-oxo-2-((2-(3,4,5-triacetoxybenzamide)ethyl) Synthesis of (amino)ethyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetate (Compound 3)

[0170] Gallic acid (2.18 g, 11.61 mmol) was dissolved in dimethylformamide and stirred at 0 ° C. Then, EDC (2.45 g, 12.77 mmol) and hydroxybenzotriazole (HOBt hydrate) (1.75 g, 12.77 mmol) dissolved in dimethylformamide were added to the gallic acid solution and stirred for 30 minutes. Then, compound 2 (5 g, 8.13 mmol) dissolved in dimethylformamide was added to the reactant, and DIPEA (4.04 mL, 23.22 mmol) was added thereto, followed by stirring at room temperature for 24 hours. Next, after dimethylformamide was concentrated as much as possible by vacuum filtration, it was extracted with dichloromethane and brine (brine), and dehydrated with sodium sulfate and then filtered under reduced pressure. Then, the solid (compound 3) was separated by open column chromatography under dichloromethane / methanol conditions, and the next reaction could be carried out without further separation and purification.

[0171] 4) 2,2`,2``-(10-(2-oxo-2((2-(3,4,5-trihydroxybenzamide)ethyl)amino)ethyl)-1, Synthesis of 4,7,10-tetraazacyclododecane-1,4,7-triyl) triacetate (Compound 4)

[0172] At 0°C, excess trifluoroacetic acid was added to compound 3, and the reaction was stirred at room temperature for 20 hours. Then, dichloromethane was added, and the mixture was filtered under reduced pressure repeatedly. The mixture was separated and purified by high performance liquid chromatography under the conditions of water / acetonitrile with 0.1% trifluoroacetic acid to obtain a solid (compound 4). Yield: (2→4): 2.1 g (43%).

[0173] The obtained compound 4 1 H NMR spectra and 13 C NMR spectra and HR-MS spectra are shown in Figure 3a To 3c.

[0174] 1H NMR (500MHz, MeOD); δ=6.70 (d, J=7.7Hz, 2H), 3.91-3.46 (m, 8H), 3.31-3.28 (m, 2H), 3.24-2.78 (m, 18H).

[0175] 13 C NMR (126MHz, MeOD); δ=169.29, 169.26, 161.48, 161.20, 160.92, 160.64, 145.37, 136.80, 124.60, 106.60, 54.34, 53.20, 39.15, 38.75.

[0176] HR-MS(m / z): [M+H] + calculated for C 25 H 39 N6O 11 , 599.2677; found, 599.2680.

[0177] 5) Synthesis of compound Gd-DO3A-Ga (compound of the present invention)

[0178] Compound 4 (1 g, 1.67 mmol) was dissolved in distilled water, the pH was adjusted to 3 with 1 M sodium hydroxide, and then Gd(Cl)3·6H2O (0.43 g, 1.17 mmol) dissolved in distilled water was added. After the pH was adjusted to 7 with 1 M sodium hydroxide, the mixture was stirred at room temperature for 20 hours. After the stirring was completed, the solid obtained by vacuum filtration was separated and purified by high performance liquid chromatography under the conditions of distilled water / acetonitrile with the addition of 10 mM ammonium acetate to obtain a solid substance (compound Gd-DO3A-Ga).

[0179] The HR-MS spectrum and HPLC chromatogram of the obtained compound Gd-DO3A-Ga are shown in Figure 4a and 4b . Yield: 0.8g (63%)

[0180] HR-MS(m / z): [M+H] + calculated for C 25 H 36 N6O 11 Gd, 754.1683; found, 754.1687.

[0181] Purity analysis using analytical HPLC: 96%

[0182] Next, the prepared representative compounds of the present invention were used as MRI contrast agents, and at the same time, property evaluation was performed to determine whether the amyloid β polymer had targeting ability.

[0183] 2. Methods and results for evaluating the properties of the compounds of the present invention

[0184] 1) Measurement of Relaxivity

[0185] Using Gd-DO3A-Ga synthesized according to the method of Example 2 and a commercially available annular contrast agent, namely As a control group, the self-relaxation rates (r1, r2) were measured.

[0186] Specifically, a phantom was prepared by diluting the gadolinium complex in three distilled water to five concentrations (0.0625, 0.125, 0.25, 0.5, 1 mM), and then measuring the T1 and T2 relaxation times in 3T MRI. R (relaxation rate = 1 / T) of each concentration was calculated, and the results of the self-relaxation rate of the gadolinium complex were obtained by linear regression analysis. (See Table 1, Figure 5 )

[0187]

Table 1

[0188]

[0189] As described in Table 1 and Figure 5 As shown, the r1 value of Gd-DO3A-Ga was measured to be 4.04±0.09, and the r2 value was 4.82±0.11, which were similar to or greater than those of the commercially available annular contrast agent in the control group, thereby confirming that the contrast agent of the present invention exhibited a self-relaxation rate that is sufficient for clinical use.

[0190] 2) Kinetic stability evaluation

[0191] After preparing membranes by diluting Gd-DO3A-Ga and several commercially available contrast agents (Gadovist, Dotarem, Prohance, Magnevist, Primovist, Multihance) in PBS (pH 7.4) to a concentration of 2.5 mM, 250 mM zinc chloride (ZnCl2) was added each time to evaluate the binding stability of DO3A ligand and Gd metal ion. The results are shown in Figure 6 This can be confirmed by measuring the transmetallation of zinc ions to gadolinium ions as a change in the self-relaxation rate.

[0192] refer to Figure 6Since the R2 change rate is kept at a large value above 0.9, the synthesized Gd-DO3A-Ga has sufficient stability to be used as an MRI contrast agent.

[0193] 3) Phantom experimental methods for confirming the targeting of amyloid β aggregates

[0194] HFIP (221.5 μl) was added to β-amyloid protein (1 mg, 1 mM), and the mixture was shaken on a shaker at room temperature for 1 hour to remove preaggregation.

[0195] Next, the pre-aggregated amyloid β protein was dried, DMSO (221.5 μl) was added to adjust the concentration to 1 mM, and then a suspension was formed using a mixer and a sonicator, and then PBS (1X, pH 7.4, 878.5 μl) was added to adjust the concentration to 0.2 mM.

[0196] Then, after culturing for 4 days at 37°C using a shaker, 200 μl of the polymerized amyloid β polymer (oligomeric Aβ) was dispensed, and the compound Gd-DO3A-Ga and a commercially available contrast agent dissolved in PBS at a concentration of 2 mM were added. 20 μl of each was added, and then cultured at 37°C for 24 hours using a shaker.

[0197] After the culture was completed, the supernatant was removed by centrifugation, and the amyloid-β protein polymer was washed with PBS. 200 μl of PBS:DMSO=9:1 solution was added to the pellet to prepare an MRI phantom sample.

[0198] 4) Experimental results

[0199] The β-amyloid polymer targeting experiment was conducted on a 9.4T MR device, and the results are shown in Figure 7 middle. Figure 7 A comparison graph showing MR signal intensity of MRI voxel samples.

[0200] refer to Figure 7 , the phantoms incubated with amyloid-β polymers only (control group) and with commercial contrast agents The phantom (comparative example) showed almost no difference in contrast enhancement effect. There is no targeting effect on amyloid beta aggregates.

[0201] On the other hand, the phantom incubated with GD-DO3A-Ga, a compound of the present invention, showed a signal intensity that was more than 2 times higher than that of the control group. Thus, it can be confirmed that the compound of the present invention has a targeting effect on β-amyloid polymers, and it can be seen that Gd-DO3A-Ga of the present invention is suitable for use as a β-amyloid polymer targeting contrast agent.

[0202] Although the present invention has been described above with reference to the preferred embodiments, it should be understood that various modifications and variations may be made by those skilled in the art without departing from the spirit and scope of the present invention as described in the claims.

Claims

1. A gadolinium-based compound, characterized in that Represented by the following chemical formula 1: [Chemical formula 1] In the chemical formula 1, A represents *-(CH2) n -A 1 -*, n represents any integer from 0 to 5, A 1 represents *-CONH-*, Linker means *-L 1 -NH-L 2 -*, L 1 represents a straight chain or branched (C1-C30) alkylene group, L 2 represents a single bond, or a straight chain or branched (C1-C30) alkylene group, Ga represents the chemical formula 2: [Chemical formula 2] * indicates the attachment site.

2. The gadolinium-based compound according to claim 1, characterized in that L 1 represents a straight chain or branched (C1-C10) alkylene group, L 2 Indicates a single bond.

3. An MRI contrast agent, characterized in that: It contains the gadolinium-based compound according to claim 1.

4. Use of the gadolinium-based compound according to claim 1 or 2 in the preparation of a medicament for diagnosing degenerative brain diseases.

5. The use according to claim 4, characterized in that The degenerative brain disease is Alzheimer's disease.

6. A method for preparing a gadolinium-based compound according to claim 1, characterized in that: include: (a) reacting a compound of the following Chemical Formula 1-1 with a halogen compound to obtain a compound of the following Chemical Formula 1-2; [Chemical formula 1-1] [Chemical formula 1-2] In the chemical formulas 1-1 and 1-2, PT 1 represents a protecting group, X represents a halogen atom, L 2 As defined in claim 1, (b) reacting a compound of the following Chemical Formula 1-2 with a compound of the following Chemical Formula 1-3 to obtain a compound of the following Chemical Formula 1-4; [Chemical formula 1-3] [Chemical formula 1-4] In the chemical formulas 1-3 and 1-4, PT 1 and PT 2 Each independently represents a protecting group, Linker means *-L 1 -NH-L 2 -*, L 1 , L 2 and A is defined in the chemical formula 1 as claimed in claim 1, (c) removing PT from the compound of Chemical Formula 1-4 1 and PT 2 steps; and (d) a step of reacting the compound obtained in step (c) with gadolinium hydrate to obtain the compound of Chemical Formula 1 described in claim 1.

7. The method according to claim 6, characterized in that In the step (a), the L 2 is a single bond, and the halogen compound is thionyl chloride.

8. A method for preparing a gadolinium-based compound according to claim 1, characterized in that: include: (a) reacting a compound of the following Chemical Formula 2-1 with a compound of the following Chemical Formula 2-2 to obtain a compound of the following Chemical Formula 2-3; [Chemical formula 2-1] [Chemical formula 2-2] [Chemical formula 2-3] In the chemical formulas 2-1 to 2-3, PT 3 represents a protecting group, Linker means *-L 1 -NH-L 2 -*, L 1 , L 2 and A is defined in the chemical formula 1 as claimed in claim 1, (b) Removing PT from the compound of Chemical Formula 2-3 3 steps; and (c) a step of reacting the compound obtained in step (b) with gadolinium hydrate to obtain the compound of Chemical Formula 1 according to claim 1.

9. The method according to claim 8, characterized in that In the step (a), the L 2 For a single key.

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