A gadolinium-based magnetic resonance imaging contrast agent with multivalent glycosides and multi-carbon carboxyl branched chains and its application in dual tumor-targeted magnetic resonance imaging.

Abstract

This invention discloses a gadolinium-based magnetic resonance imaging contrast agent with a hybrid structure of multivalent glycosides and multi-carbon carboxyl branches, and its application in dual tumor-targeting magnetic resonance imaging. The invention symmetrically introduces four branches into the nitrogen atom of a 1,4,7,10-tetraazacyclododecanegadinoyl ligand. Each branch contains a glycoside moiety targeting a tumor glucose transporter (GLUT1) and a multi-carbon carboxyl group targeting a tumor anion transport peptide, constructing a dual multivalent synergistic tumor-targeting gadolinium-based MRI contrast agent with four glycoside and multi-carbon carboxyl targeting groups. The glycoside moiety enhances tumor-specific targeting, while the multi-carbon branches enhance cellular endocytosis, synergistically enhancing the tumor-targeting properties of this type of compound. This achieves effective enrichment and highly selective magnetic resonance imaging of this MRI contrast agent at tumor sites, showing significant application potential in precise tumor imaging and visualization of tumor surgical resection.

Description

Technical Field

[0001] This invention belongs to the field of tumor-targeted magnetic resonance imaging technology, specifically relating to a gadolinium-based magnetic resonance imaging contrast agent with a multivalent glycoside and a multi-carbon carboxyl branched chain and its application in dual tumor-targeted magnetic resonance imaging. Background Technology

[0002] Magnetic resonance imaging (MRI) is a widely used clinical diagnostic and imaging technique with advantages such as being non-invasive, providing real-time three-dimensional imaging, high tissue resolution, and high bio-penetration. The basic principle of this imaging technique is based on the orientation of the magnetic dipoles of water molecules under a specific magnetic field strength. By applying a radio frequency wave in a specific direction, the magnetic dipole orientation is deflected. When the radio frequency wave stops, the magnetic dipoles relax back to their initial orientation. Through signal transformation, due to the different concentrations of water protons in different tissues and organs, the magnetic relaxation signal intensity also varies, resulting in different MRI signals for different tissues and organs, thus achieving high tissue resolution MRI. However, due to the weak magnetic dipoles of water protons, direct water proton MRI suffers from low imaging sensitivity, posing a significant challenge, particularly for the early detection of specific disease states such as tumors. Gadolinium, with its seven spin electrons and high magnetic dipoles, is an effective contrast agent molecule for enhancing the effects of water proton MRI. Currently, approximately eight gadolinium-based MRI contrast agents have been approved for clinical use. Currently, about 40% of magnetic resonance imaging (MRI) requires the use of gadolinium-based contrast agents, with millions of tons used annually, demonstrating its wide range of clinical applications.

[0003] Given its radiation-free, non-invasive, and highly tissue-penetrating characteristics, magnetic resonance imaging (MRI) has become an important method for clinical tumor diagnosis and imaging. However, currently approved gadolinium-based contrast agents, such as Gd-DTPA and Gd-DOTA, exhibit rapid biological clearance but limited targeting efficacy against specific tumor sites, thus limiting their application in early and precise tumor imaging. Therefore, developing novel gadolinium-based MRI contrast agents with broad-spectrum tumor-targeting effects is of significant research value and practical application necessity. Summary of the Invention

[0004] To address the problems in the existing technology, this invention provides a gadolinium-based magnetic resonance imaging contrast agent with hybridized polyvalent glycosides and multi-carbon carboxyl branches, and its application in dual tumor-targeting magnetic resonance imaging. This invention designs the structure of highly stable macrocyclic gadolinium molecules and introduces two types of tumor-targeting functional groups: polyvalent glycosides and multi-carbon carboxyl branches. This constructs a series of dual multivalent tumor-targeting gadolinium-based contrast agents, achieving effective enrichment and highly selective magnetic resonance imaging of these MRI contrast agents at tumor sites. This has significant application potential in areas such as precise tumor imaging and visualization of tumor surgical resection.

[0005] The structural formulas of the aforementioned multivalent glycoside and multi-carbon carboxyl branched gadolinium-based magnetic resonance imaging contrast agent are as follows:

[0006] Wherein, M is the lanthanide transition metal center, specifically Gd(III); R1 is the tumor-targeting group, specifically one or more of glucosides, galactosides, aminohexosides, glucuronic acid glycosides, mannosides, lactosides, cellulose glycosides, and chitosan glycosides; R2 is a C2-C18 alkyl chain or an alkyl chain containing a carboxyl group.

[0007] The preparation method of the aforementioned multivalent glycoside and multi-carbon carboxyl branched gadolinium magnetic resonance imaging contrast agent is as follows: (1) Dissolve the glycoside starting material and 2-(hydroxymethyl)-4-nitrophenol in acetonitrile, stir at room temperature for 10-20 hours under silver oxide conditions and nitrogen atmosphere, remove solid residue by centrifugation, and purify the solution by rotary evaporation through silica gel column to obtain compound 1; (2) Compound 1, N , N '-Succinimidyl carbonate and 4-dimethylaminopyridine were dissolved in dichloromethane and stirred at room temperature, then added... N , N - Diisopropylethylamine, C2-C18 fatty amine or C2-C18 aminocarboxylic acid ester, stirred overnight at room temperature. After the reaction was completed, the solvent was concentrated and purified by silica gel column chromatography to obtain compound 2. (3) Compound 2 was dissolved in tetrahydrofuran under a nitrogen atmosphere, Pd / C was added, and the reaction was stirred at room temperature under a hydrogen atmosphere for 15-30 hours. Solid impurities were removed by centrifugation, the solution was concentrated by rotary evaporation, and compound 3 was obtained by silica gel column chromatography. (4) Dissolve compound 3 in dichloromethane, add triethylamine, then add bromoacetyl bromide dropwise, stir at 0 degrees Celsius for 3-8 min, concentrate and purify by column chromatography to obtain compound 4; (5) Compound 4, 1,4,7,10-tetraazacyclododecane and potassium carbonate were added to acetonitrile solvent and stirred at room temperature for 30-60 hours under nitrogen atmosphere. After the reaction was completed, the solid impurities were removed by centrifugation, the solution was concentrated by rotary evaporation and purified by column chromatography to obtain compound 5. (6) Dissolve compound 5 in tetrahydrofuran, slowly add LiOH solution under stirring at 0 degrees Celsius, continue stirring for 3-8 hours. After the reaction is complete, adjust the pH of the solution to 6-7, remove the organic solvent by rotary evaporation, add pure water to dissolve, add GdCl3, and stir at room temperature overnight while maintaining the pH between 5.5-6.6. After the reaction is complete, evaporate the solvent by rotary evaporation, and use reverse column chromatography to separate and purify the magnetic resonance imaging contrast agent.

[0008] The glycoside starting material is one or more of glucose, galactose, aminohexose, glucuronic acid, mannose, lactose, cellulose sugar, and chitosan halides.

[0009] The above-prepared polyvalent glycosides and gadolinium-based magnetic resonance imaging contrast agents with multi-carbon carboxyl branched chains are used as dual tumor-targeting magnetic resonance imaging contrast agents.

[0010] This invention introduces four branches symmetrically into the nitrogen atom of a 1,4,7,10-tetraazacyclododecanegadolinyl ligand. Each branch contains a glycoside moiety targeting a tumor glucose transporter (GLUT1) and a multi-carbon carboxyl group targeting a tumor anion transporter polypeptide. This constructs a dual-functional, multivalent, synergistic tumor-targeting gadolinium-based MRI contrast agent with four glycoside targets and a multi-carbon carboxyl group target. The glycoside moiety enhances tumor-specific targeting, while the multi-carbon branches enhance cellular endocytosis, synergistically enhancing the tumor-targeting properties of this type of compound. The broad-spectrum MRI gadolinium-based contrast agent with excellent tumor targeting constructed in this invention enables precise early detection and timely diagnosis of tumors. Attached Figure Description

[0011] Figure 1 The structural diagrams are of GdCAG, GdG, TbCAG, and TbG prepared in Example 1.

[0012] Figure 2 The magnetic resonance relaxation rate test results of GdCAG (AC) and GdG (DF) molecules in Example 1 are shown in magnetic field strengths of 0.5 T, 1.41 T, and 7 T.

[0013] Figure 3 The luminescence lifetime changes of TbCAG and TbG molecules in water and deuterated water were tested as in Example 1.

[0014] Figure 4 GdCAG and GdG from Example 1 were dissolved in PBS phosphate buffer and PBS phosphate buffer containing 4.5% HSA, respectively, and used for magnetic resonance imaging of normal mice at a dose of 0.1 mmol / Kg.

[0015] Figure 5 GdCAG and GdG, as described in Example 1, were used for magnetic resonance imaging of 4T1 breast cancer tumors. Detailed Implementation

[0016] Example 1: Synergistic targeting of breast tumors by polyvalent glucosides and multi-carbon carboxyl branched chains using targeted magnetic resonance imaging. Synthetic routes for GdCAG, GdG, and the corresponding Tb(III) compounds (TbCAG, TbG):

[0017] Synthesis of Compound 1: Compound 1 was prepared by mixing glucose bromide (4.94 g, 12 mmol) and 2-(hydroxymethyl)-4-nitrophenol (1.69 g, 10 mmol) in silver oxide (Ag₂O, 2.78 g, 12 mmol) under dry acetonitrile solvent (20 mL) and nitrogen atmosphere at room temperature for 15 hours. After centrifugation to remove solid residue, the solution was purified by rotary evaporation through silica gel column chromatography to obtain compound 1 (4.17 g, yield 83%).

[0018] Proton NMR: 1 H NMR (400 MHz, Chloroform-d) δ 8.30 (d, J = 2.8 Hz, 1H), 8.16 (dd, J = 9.0, 2.8 Hz, 1H), 7.05 (d, J = 9.0 Hz, 1H), 5.36 – 5.31 (m, 2H), 5.23 – 5.13 (m, 2H), 4.65 (d, J = 1.9 Hz, 2H), 4.31 – 4.08 (m, 3H), 3.93(ddd, J = 10.1, 5.5, 2.4 Hz, 1H), 2.08 (s, 3H), 2.06 – 2.04 (m, 9H). Carbon NMR: 13 C NMR (100 MHz, Chloroform-d) δ 170.61, 170.20, 169.92,169.54,158.52, 143.28, 132.10, 124.71, 124.47, 114.02, 98.29, 72.48, 72.11,70.95, 68.10, 61.77, 60.55, 60.03, 21.16, 20.75, 20.67. High-resolution mass spectrometry: C 21 H 25 NO 13 (M+Na) + cal.522.1218, Found. 522.1192. Synthesis of compound 2: Compound 1 (8 mmol, 4 g), N , N'-Succinimidyl carbonate (DSC, 10 mmol, 2.5 g) and 4-dimethylaminopyridine (DMAP, 8 mmol, 1 g) were stirred in 100 mL of dichloromethane (DCM) at room temperature for 5 minutes, and then 5 mL of [the mixture] was added. N , N Diisopropylethylamine (DIPEA) and ethyl 6-aminohexanoate (10 mmol, 2 g) were stirred overnight at room temperature. After the reaction was complete, the solvent was concentrated, and compound 2 (3.8 g, yield: 70%) was purified by silica gel column chromatography.

[0019] Proton NMR: 1 H NMR (400 MHz, Chloroform-d) δ 6.92 (d, J = 8.6 Hz, 1H), 6.67 (d, J = 2.9 Hz, 1H), 6.54 (dd, J = 8.6, 2.9 Hz, 1H), 5.28 (s, 2H), 5.26– 5.24 (m, 1H), 5.24 – 5.22 (m, 1H), 4.23 – 4.20 (m, 1H), 4.18 (d, J = 2.6Hz, 1H), 4.10 (q, J = 7.1 Hz, 5H), 3.75 (ddd, J = 9.5, 5.0, 2.6 Hz, 2H), 3.16(d, J = 6.6 Hz, 2H), 2.28 (t, J = 7.4 Hz, 3H), 2.10 (s, 2H), 2.05 (d, J = 3.1Hz, 4H), 2.02 (d, J = 2.2 Hz, 8H), 1.61 (d, J = 7.6 Hz, 2H), 1.51 (d, J = 7.5Hz, 2H), 1.34 (dd, J = 6.3, 2.9 Hz, 2H), 1.24 (d, J = 3.4 Hz, 3H). Carbon NMR: 13C NMR (101 MHz, Chloroform-d) δ 173.73, 170.76, 170.38,169.55, 156.42, 147.45, 128.55, 119.20, 116.10, 115.49, 100.75, 72.88, 71.90,71.34, 68.46, 62.00, 61.39, 60.49, 60.37, 53.53, 40.94, 34.24, 29.71, 26.31,24.62, 20.78, 20.72, 14.33, 14.28. High-resolution mass spectrometry: C 30 H 40 N2O 15 (M+Na) + cal. 707.2270, Found. 707.2270. Synthesis of compound 3: Compound 2 (2 g, 4 mmol) was dissolved in 50 mL of tetrahydrofuran (THF) to form a nitrogen atmosphere. 10% Pd / C was added and a hydrogen balloon was inserted. The mixture was stirred and reacted at room temperature under a hydrogen atmosphere for 20 hours. Solid impurities were removed by centrifugation, the solution was concentrated by rotary evaporation, and the target molecule 3 (1 g, yield: 53%) was obtained by silica gel column chromatography.

[0020] Proton NMR: 1 H NMR (400 MHz, Chloroform-d) δ 8.29 (dd, J = 13.6, 2.8 Hz, 1H), 8.14 (dd, J = 9.0, 2.8 Hz, 1H), 7.06 (dd, J = 9.1, 3.1 Hz, 1H), 5.59 –5.37 (m, 3H), 5.28 (s, 1H), 5.19 – 5.13 (m, 2H), 4.65 (s, 2H), 4.22 – 4.07(m, 4H), 3.69 (q, J = 7.0 Hz, 1H), 2.17 (d, J = 6.5 Hz, 4H), 2.13 (dd, J =11.4, 8.0 Hz, 2H), 2.08 (s, 3H), 2.07 (s, 1H), 2.05 (s, 3H), 2.03 (d, J= 3.5Hz, 2H), 2.01 (s, 3H), 1.98 (d, J = 2.5 Hz, 1H), 1.21 (t, J = 7.0 Hz, 1H). Carbon NMR: 13 C NMR (101 MHz, Chloroform-d) δ 170.45, 170.27, 170.23,170.12, 158.64, 143.14, 131.87, 124.76, 124.56, 113.73, 101.07, 98.66, 71.60,70.90, 70.31, 68.45, 66.67, 61.40, 61.12, 60.23, 58.56, 53.56, 20.92, 20.83,20.76, 20.66, 18.50. High-resolution mass spectrometry: C 30 H 42 N2O 14 (M+Na) + Cal. 677.2528, Found. 677.2516. Synthesis of compound 4: Compound 3 (1.41 g, 3 mmol) was dissolved in 50 mL of dry dichloromethane (DCM), and triethylamine was added followed by dropwise addition of bromoacetyl bromide. The mixture was stirred at 0°C for 5 min, concentrated, and purified by column chromatography to give compound 4 (1.6 g, yield: 76%).

[0021] Proton NMR: 1 H NMR (400 MHz, Chloroform-d) δ 8.73 (s, 1H), 7.44 (ddd, J = 33.3, 8.9, 2.6 Hz, 1H), 7.32 – 7.24 (m, 1H), 6.90 (dd, J = 17.0, 8.9 Hz, 1H), 5.37 – 5.27 (m, 3H), 5.18 (s, 1H), 5.01 (dd, J = 10.5, 3.4 Hz, 1H), 4.97– 4.84 (m, 2H), 3.94 (dd, J = 7.2, 1.5 Hz, 2H), 3.82 (d, J = 6.4 Hz, 3H), 3.00 (q, J= 6.7 Hz, 2H), 2.15 (t, J = 7.4 Hz, 2H), 2.04 (d, J = 2.7 Hz, 3H), 1.96 (d, J = 5.0 Hz, 3H), 1.90 (d, J = 2.9 Hz, 3H), 1.86 (d, J = 2.1 Hz, 3H), 1.47 (t, J = 7.8 Hz, 1H), 1.38 – 1.33 (m, 1H), 1.21 – 1.17 (m, 1H), 1.10 (td, J = 7.1, 2.1 Hz, 7H). Carbon NMR: 13 C NMR (101 MHz, Chloroform-d) δ 173.78, 171.21, 170.57,170.41, 170.35, 170.29, 170.24, 170.10, 170.05, 170.02, 169.73, 169.61,169.34, 164.64, 164.57, 156.39, 151.14, 150.72, 133.16, 133.06, 128.07,127.69, 120.97, 120.76, 116.43, 115.94, 100.95, 100.01, 99.68, 71.01, 70.86, 70.66, 68.92, 68.65, 68.49, 67.11, 67.03, 66.05, 61.43, 61.32, 61.12, 60.80, 60.38, 60.29, 53.63, 40.81, 34.09, 29.49, 29.41, 29.38, 26.13, 24.49, 20.98, 20.73, 20.68, 20.60, 20.52, 14.18, 14.13. High-resolution mass spectrometry: C 31 H 44 BrN2O 15 (M+Na) + Cal. 799.1719, Found. 799.1690. Synthesis of compound 5: Compound 4 (1.1 g, 1.9 mmol), 1,4,7,10-tetraazacyclododecane (Cyclen, 52 mg, 0.3 mmol), and potassium carbonate (K2CO3, 332 mg, 2.4 mmol) were added to 20 mL of dry acetonitrile solvent. The mixture was stirred at room temperature for 48 hours under a nitrogen atmosphere. After the reaction was completed, the solid impurities were removed by centrifugation, the solution was concentrated by rotary evaporation, and purified by column chromatography to obtain 619 mg of the target product, with a yield of 71%.

[0022] High-resolution mass spectrometry: C 136 H 188 N 12 O 60 (M+Na) + Cal. 2972.1921, Found. 2972.1841.

[0023] Synthesis of compounds GdCAG and TbCAG: Intermediate ligand 5 (100 mg, 0.045 mmol) was dissolved in 10 mL of tetrahydrofuran solvent. 1 M LiOH solution (32.5 mg, 1.35 mmol) was slowly added under stirring at 0°C, and stirring continued for five hours. After the reaction was complete, the pH of the solution was adjusted to 6-6.5 with 0.5 M HCl / 0.5 M NaOH. The organic solvent was removed by rotary evaporation, and the solution was dissolved in 10 mL of pure water. A hydrate of lanthanide chlorides (LnCl3 hydrate, Ln = Gd, Tb, 0.0675 mmol) was added, and the solution was stirred overnight at room temperature, maintaining the pH between 5.8 and 6.1. After the reaction was complete, the solvent was rotated, and the target compounds GdCAG and TbCAG were purified by reversed-phase column chromatography.

[0024] High-resolution mass spectrometry: GdCAG, C 96 H 140 GdN 12 O 44 (M / 2) - cal.1161.3898, Found. 1161.9175; TbCAG, C 96 H 140 GdN 12 O 44 (M / 2) - cal.1161.9164, Found. 1161.8848.

[0025] Synthesis of compound 6: Intermediate 1 (2 g, 4 mmol) was dissolved in 50 mL of dry tetrahydrofuran solvent. 10% Pd / C (0.2 mmol) was added under a nitrogen atmosphere, and a hydrogen atmosphere was created using a hydrogen balloon. The mixture was stirred at room temperature for 20 h. After the reaction was complete, the solid phase was removed by centrifugation, the solution was concentrated by rotary evaporation, and the target molecule 6 (1 g, 53% yield) was purified by silica gel column chromatography.

[0026] Proton NMR: 1 H NMR (400 MHz, Chloroform-d) δ 6.83 (d, J = 8.6 Hz, 1H), 6.66 (d, J = 2.8 Hz, 1H), 6.56 (dd, J = 8.6, 2.9 Hz, 1H), 5.30 – 5.20 (m, 2H), 5.16 – 5.09 (m, 1H), 4.96 – 4.88 (m, 1H), 4.63 (d, J = 12.6 Hz, 1H), 4.36 (d,J = 12.6 Hz, 1H), 4.27 – 4.05 (m, 3H), 3.75 (ddd, J = 10.1, 5.3, 2.5 Hz, 1H),2.10 – 2.01 (m, 14H). Carbon NMR: 13 C NMR (100 MHz, Chloroform-d) δ 170.77, 170.38, 169.69,169.53,147.53, 143.10, 133.20, 118.68, 116.22, 115.17, 101.24, 72.65, 72.05,71.29, 68.31, 61.81, 60.95, 29.78, 20.81, 20.75, 20.72, 20.68. High-resolution mass spectrometry: C 21 H 27 NO 11 (M+Na) + Cal. 492.1451, Found. 492.1476. Synthesis of compound 7: Compound 6 (1.41 g, 3 mmol) was dissolved in 50 mL of dry dichloromethane under a nitrogen atmosphere. Triethylamine and bromoacetyl bromide were added, and the mixture was stirred at room temperature for 5 minutes. After the reaction was completed, the mixture was concentrated, and the target product 7 (1.28 g, 73% yield) was purified by silica gel column chromatography.

[0027] Proton NMR: 1 H NMR (400 MHz, Chloroform-d) δ 8.15 (s, 1H), 7.56 (dd, J =8.8, 2.7 Hz, 1H), 7.36 (d, J = 2.7 Hz, 1H), 6.99 (d, J = 8.8 Hz, 1H), 5.32 –5.27 (m, 2H), 5.17 – 5.11 (m, 1H), 5.07 – 5.02 (m, 1H), 4.65 (d, J = 13.1 Hz, 1H), 4.50 (d, J = 13.1 Hz, 1H), 4.25 (dd, J = 12.3, 5.4 Hz, 1H), 4.15 (dd, J = 12.4, 2.4 Hz, 1H), 4.00 (s, 2H), 2.15 – 1.97 (m, 12H). Carbon NMR: 13 C NMR (100 MHz, Chloroform-d) δ 170.73, 170.30, 169.81,169.54, 163.59, 151.74, 132.83, 132.45, 121.42, 120.99, 116.64, 99.97, 72.45,72.23, 71.17, 68.25, 61.80, 60.55, 51.00, 29.49, 20.81, 20.79, 20.71, 20.69. High-resolution mass spectrometry: C 23 H 28 BrNO 12 (M+Na) + cal. 612.0687, Found. 612.0672. Synthesis of compound 8: Intermediate 7 (1.1 g, 1.9 mmol), 1,4,7,10-tetraazacyclododecane (Cyclen, 52 mg, 0.3 mmol), and K₂CO₃ (332 mg, 2.4 mmol) were added to 20 mL of dry acetonitrile solvent, and stirred at room temperature for 48 h under a nitrogen atmosphere. After the reaction was completed, the solid phase was removed by centrifugation, the solution phase was concentrated, and the target molecule 8 (0.528 mg, 79% yield) was prepared by silica gel column chromatography. High-resolution mass spectrometry: 8C 100 H 130 N8O 48 (M+Na) + / 2 cal. 1124.3987, Found. 1124.3699. Synthesis of compounds GdG and TbG: Under the same reaction conditions as those used to prepare GdCAG and TbCAG, using ligand 8 (100 mg, 0.045 mmol) as the starting material, the target compounds GdG and TbG were prepared by deprotection under LiOH alkaline conditions and then reacting with lanthanide chloride hydrates.

[0028] High-resolution mass spectrometry: GdG, C 68 H 96 GdN8O 32 M - cal.1694.5366, Found. 1694.5209; TbG, C 68 H 96 TbN8O 32 (M+H) - Cal. 1697.5535, Found. 1697.6608.

[0029] This embodiment constructs a dual-multivalent synergistic tumor-targeting gadolinium-based contrast agent (GdCAG) containing four glucoside substitutions and four long-chain alkyl carboxyl branches. Simultaneously, a control molecule (GdG) containing only one glucoside substitution is prepared. The targeting imaging characteristics of this type of molecule in a breast cancer tumor model are systematically studied. Furthermore, imaging experiments in normal mice reveal the biodistribution and other characteristics of this type of molecule. Corresponding lanthanide terbium compounds (TbCAG, TbG) can help reveal the metal coordination environment characteristics of this type of compound.

[0030] like Figure 2 GdCAG (AC) molecules rThe relaxation rate gradually decreased with increasing magnetic field strength (0.5 T (37 °C), 1.41 T (37 °C), to 7 T (25 °C)) (at PBS phosphate buffer levels of 4.57, 3.19, to 2.04 mM). - 1s -1 In PBS phosphate buffer containing 4.5% serum protein, the values ​​were 5.08, 4.00, and 2.91. The control molecule GdG had a lower [value missing]. r 1. Relaxation rate reflects a similar trend.

[0031] like Figure 3 TbCAG and TbG have different luminescence lifetimes in water and deuterated water, as determined by calculation formulas. q =4.2 * (1 / τ H2O - 1 / τ D2O The calculation using -0.06) ± 0.5 indicates that the number of water molecules bound to the metal center of this type of molecule is approximately 1.

[0032] like Figure 4 In normal mice, after injection of 0.1 mmol / Kg of GdCAG and GdG molecules in PBS or PBS+HSA via tail vein injection, the magnetic resonance signal of mice injected with PBS+HSA was rapidly enhanced, especially the signal in the kidney region, which first increased significantly and then decreased rapidly. This indicates the rapid renal metabolism of this type of molecule and its significant magnetic resonance signal enhancement. Furthermore, the dual multivalent targeting molecule GdCAG has better magnetic resonance signal enhancement characteristics than the single multivalent targeting molecule GdG.

[0033] like Figure 5 In a 4T1 breast cancer mouse model, after intravenous injection of 0.1 mmol / Kg of GdCAG and GdG in PBS+HSA solution, mice in the GdCAG group showed a significant gradual increase in MRI signal at the tumor site, while mice in the control group (GdG) and the currently clinically approved Gd-DOTA group did not show a significant increase in tumor MRI signal. This indicates that the dual multivalent targeting gadolinium-based contrast agent molecule constructed in this invention has superior tumor targeting and magnetic resonance signal enhancement properties.

Claims

1. A gadolinium-based magnetic resonance imaging contrast agent with a multivalent glycoside and a multi-carbon carboxyl branched chain, characterized in that, Its structural formula is as follows: ， Wherein, M is the lanthanide transition metal center, specifically Gd(III); R1 is the tumor-targeting group, specifically one or more of glucosides, galactosides, aminohexosides, glucuronic acid glycosides, mannosides, lactosides, cellulose glycosides, and chitosan glycosides; R2 is a C2-C18 alkyl chain or an alkyl chain containing a carboxyl group.

2. A method for preparing a gadolinium-based magnetic resonance imaging contrast agent with a multivalent glycoside and a multi-carbon carboxyl branched chain, characterized in that, The specific steps of the preparation method are as follows: (1) Dissolve the glycoside starting material and 2-(hydroxymethyl)-4-nitrophenol in acetonitrile, stir at room temperature for 10-20 hours under silver oxide conditions and nitrogen atmosphere, remove solid residue by centrifugation, and purify the solution by rotary evaporation through silica gel column to obtain compound 1; (2) Compound 1, N , N '-Succinimidyl carbonate and 4-dimethylaminopyridine were dissolved in dichloromethane and stirred at room temperature, then added... N , N - Diisopropylethylamine, C2-C18 fatty amine or C2-C18 aminocarboxylic acid ester, stirred overnight at room temperature. After the reaction was completed, the solvent was concentrated and purified by silica gel column chromatography to obtain compound 2. (3) Compound 2 was dissolved in tetrahydrofuran under a nitrogen atmosphere, Pd / C was added, and the reaction was stirred at room temperature under a hydrogen atmosphere for 15-30 hours. Solid impurities were removed by centrifugation, the solution was concentrated by rotary evaporation, and compound 3 was obtained by silica gel column chromatography. (4) Dissolve compound 3 in dichloromethane, add triethylamine, then add bromoacetyl bromide dropwise, stir at 0 degrees Celsius for 3-8 min, concentrate and purify by column chromatography to obtain compound 4; (5) Compound 4, 1,4,7,10-tetraazacyclododecane and potassium carbonate were added to acetonitrile solvent and stirred at room temperature for 30-60 hours under nitrogen atmosphere. After the reaction was completed, the solid impurities were removed by centrifugation, the solution was concentrated by rotary evaporation and purified by column chromatography to obtain compound 5. (6) Dissolve compound 5 in tetrahydrofuran, slowly add LiOH solution under stirring at 0 degrees Celsius, continue stirring for 3-8 hours. After the reaction is complete, adjust the pH of the solution to 6-7, remove the organic solvent by rotary evaporation, add pure water to dissolve, add GdCl3, and stir at room temperature overnight while maintaining the pH between 5.5-6.

6. After the reaction is complete, evaporate the solvent by rotary evaporation, and use reverse column chromatography to separate and purify the magnetic resonance imaging contrast agent.

3. The preparation method according to claim 2, characterized in that, The glycoside starting material is one or more of glucose, galactose, aminohexose, glucuronic acid, mannose, lactose, cellulose sugar, and chitosan halides.

4. The application of the gadolinium-based magnetic resonance imaging contrast agent with multivalent glycosides and multi-carbon carboxyl branched chains as described in claim 1 as a dual tumor-targeting magnetic resonance imaging contrast agent.

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