F-18 labeled 5-HT transporter tracer as well as preparation method and application thereof

Abstract

The invention provides an F-18 labeled 5-HT transporter tracer as well as a preparation method and application thereof. The F-18 labeled 5-HT transporter tracer agent can be further prepared into a PET imaging agent for clinical use, and the density, distribution, binding force and other conditions of the 5-hydroxytryptamine transporter can be intuitively observed in an imaging picture through a PETCT imaging technology, so that the degree of depression can be directly known.

Description

Technical Field

[0001] The present invention relates to the technical field of radiomedicine, and in particular to an F-18-labeled 5-HT transporter tracer, a preparation method thereof, and an application thereof. Background Art

[0002] Current methods used in the research and diagnosis of depression include clinical observation, autopsy, and single-photon / positron emission tomography (SPE / PETCT) combined with CT. PET / CT uses positron emission tomography (PET) to directly observe the metabolism of related receptors or tissues in the nervous system without damaging the body. This allows for the assessment of depression severity, the effectiveness of drug treatment, and the study of disease mechanisms.

[0003] The part of the brain that is observed depends on the drug used. Currently used positron-emitting drugs include 18 F-FDG can be used for cerebral perfusion imaging and brain metabolic imaging. For example, cerebral perfusion imaging has shown increased regional cerebral blood flow in the right thalamus and caudate nucleus, and decreased blood flow in the left anterior frontal gyrus and right anterior cingulate gyrus in patients with depression. Brain metabolic imaging has also shown increased glucose metabolism in the anterior cortex and decreased glucose metabolism in the posterior cortex after treatment with citalopram. Furthermore, C-11-WAY-100635 and C-11-DASB have been used for intracerebral imaging. C-11-WAY-100635 is used for serotonin receptor imaging, observing the distribution density and binding affinity of serotonin receptors to study depression and evaluate the effectiveness of drug treatment. C-11-DASB is used for serotonin transporter imaging. The 5-HT transporter is a marker of depression, and its distribution, number, and binding affinity are used to study depression and evaluate the effectiveness of drug treatment.

[0004] Among the above drugs, 18 F-FDG cerebral perfusion and metabolic imaging lack precision, and high uptake by various brain tissues complicates imaging observation. The two C-11-labeled drugs also suffer from short half-lives, potentially leading to loss of efficacy if stored improperly or for extended periods. Furthermore, these drugs are difficult to prepare and expensive, making them difficult to commercialize. Summary of the Invention

[0005] In view of the problems existing in the prior art, the present invention provides an F-18 labeled 5-HT (5-hydroxytryptamine) transporter tracer and its preparation method and application. 18F-FX) can be used as a PET imaging agent for clinical use. By observing the density, distribution, binding force, etc. of the 5-hydroxytryptamine transporter, the severity of depression can be directly understood. The synthesis method of the transporter tracer is simple and easy to implement. It uses 3-phenoxyamphetamine as the raw material, and obtains the precursor through two steps of reaction. Then, it undergoes radiochemical labeling reaction and hydrolysis reaction to obtain 18 F-FX.

[0006] The technical solution of the present invention is:

[0007] In the first aspect, the present invention provides 3-(4-fluoro[ 18 F] phenoxy)-N-methyl-amphetamine in the preparation of F-18 labeled 5-HT transporter tracer, the 3-(4-fluoro[ 18 The chemical structural formula of [F] phenoxy)-N-methyl-amphetamine is:

[0008]

[0009] In a second aspect, the present invention provides an F-18 labeled 5-HT transporter tracer, wherein the tracer comprises 3-(4-fluoro[ 18 F]phenoxy)-N-methyl-amphetamine.

[0010] In a third aspect, the present invention provides a method for preparing the F-18 labeled 5-HT transporter tracer according to the second aspect, the preparation method comprising 3-(4-fluoro[ 18 F] phenoxy)-N-methyl-amphetamine synthesis;

[0011] The 3-(4-fluoro[ 18 The synthesis of 3-(4-fluoro-[F]phenoxy)-N-methyl-amphetamine comprises: using 3-phenoxy-N-methyl-amphetamine as a raw material, first protecting the imine with a substituent group 1, then placing a substituent group 2 at the para position of the phenoxy group, then replacing the substituent group 2 with F-18, and then removing the substituent group 1 to obtain 3-(4-fluoro-[ 18 F]phenoxy)-N-methyl-amphetamine;

[0012] The substituent is selected from one of alkoxycarbonyl, acyl and alkyl;

[0013] Preferably, the substituent is selected from one of tert-butyloxycarbonyl, fluorenylmethyloxycarbonyl, benzyloxycarbonyl, allyloxycarbonyl, trifluoroacetyl, phthaloyl, benzyl, p-methoxybenzyl, 2,4-dimethoxybenzyl, trityl and trimethylsilylethoxymethyl.

[0014] More preferably, the 3-(4-fluoro[ 18 F] phenoxy)-N-methyl-amphetamine synthesis adopts the following route:

[0015]

[0016] And includes the following steps:

[0017] Step 1, reacting compound 1 with Boc2O in the presence of a catalyst to obtain compound 2;

[0018] Step 2, reacting compound 2 with 4-phenol boronic acid pinacol ester in the presence of a second catalyst to obtain compound 3;

[0019] Step 3, compound 3 is reacted with 18 The medium is subjected to radiochemical labeling reaction to obtain 18 F-labeled compound 4;

[0020] Step 4, remove the Boc group from compound 4 to obtain 3-(4-fluoro[ 18 F]phenoxy)-N-methyl-amphetamine.

[0021] Further preferably, in step 1, the molar ratio of compound 1 to Boc2O is 1:2-3; and / or, catalyst 1 is selected from one of triethylamine, pyridine, and triethylenediamine, more preferably triethylamine; and / or, the reaction temperature does not exceed 10°C, more preferably 0-5°C.

[0022] Further preferably, in step 2, the amount of 4-phenol boronic acid pinacol ester added is calculated so that the molar ratio of the 4-phenol boronic acid pinacol ester to compound 1 is 0.9 to 1.1:1; and / or the molar ratio of the catalyst 2 to 4-phenol boronic acid pinacol ester is 1.5 to 2:1; and / or the reaction temperature is 60 to 65°C.

[0023] Further preferably, the second catalyst is an azodicarboxylic acid ester compound and an organophosphorus compound;

[0024] More preferably, the azodicarboxylic acid ester compound is at least one selected from diisopropyl azodicarboxylate, diethyl azodicarboxylate, dimethyl azodicarboxylate, di-tert-butyl azodicarboxylate, dibenzyl azodicarboxylate, and bis(trichloroethyl) azodicarboxylate; and / or the organophosphorus compound is at least one selected from triphenylphosphine, tributylphosphine, and tri-tert-butylphosphine.

[0025] More preferably, the molar ratio of the azodicarboxylic acid ester compound to the organophosphorus compound is 1:1-2.

[0026] Further preferably, the step 3 includes:

[0027] Step 3-1, the 18 The K222 / K2CO3 solution is dehydrated;

[0028] Step 3-2, remove the water containing F 18 The K222 / K2CO3 solution reacted with compound 3 at 100-110°C under the catalysis of Cu(OTf)2 and pyridine;

[0029] More preferably, the mass ratio of compound 3 to Cu(OTf)2 is 1:10-40; and / or,

[0030] More preferably, the mass ratio of Cu(OTf)2 to pyridine is 1 to 2:1; and / or,

[0031] More preferably, the reaction solvent in step 3-2 is DMSO.

[0032] Further preferably, in step 4, an acidic reagent is used to remove the Boc group from compound 4; preferably, the reaction temperature is 50-110°C, more preferably 80-105°C.

[0033] More preferably, the acidic reagent is a 5M HCl-10% EtOH solution.

[0034] In a fourth aspect, the present invention provides use of the F-18 labeled 5-HT transporter tracer described in the second aspect in the preparation of a PET imaging agent.

[0035] Compared with the prior art, the beneficial effects of the present invention are:

[0036] The present invention provides a 5-HT transporter tracer labeled with positron emission tomography (F-18). 18 F-FX) is simple to prepare, safe and reliable, and its active ingredients 18 F-FX has an extremely low chemical content and does not trigger any physiological reactions. It can be used clinically as a PET imaging agent. Through PETCT imaging technology, the density, distribution, and binding force of serotonin transporters can be visually observed in the image, thereby directly understanding the severity of depression. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is the nuclear magnetic resonance spectrum of compound 3 in Example 1.

[0038] Figure 2 This is the mass spectrum of compound 3 in Example 1.

[0039] Figure 3 This is the nuclear magnetic resonance spectrum of the F19-FX standard in Example 1.

[0040] Figure 4 This is the standard mass spectrum of F19-FX in Example 1.

[0041] Figure 5 For Example 1 18 HPLC localization map of F-FX and reference substances.

[0042] Figure 6 Injection of the cynomolgus monkey brain in Example 2 18 Brain imaging results after F-FX, where A is a transverse image of the brain, B is a coronal image of the brain, and C is a sagittal image of the brain. DETAILED DESCRIPTION

[0043] In a specific embodiment of the present invention, a 5-hydroxytryptamine transporter tracer labeled with F-18 is provided, namely 3-(4-fluoro[ 18 F]phenoxy)-N-methyl-amphetamine ( 18 F-FX), the chemical structure is as follows:

[0044]

[0045] The preparation method of the F-18 labeled 5-hydroxytryptamine transporter tracer comprises the following steps: using 3-phenoxy-N-methyl-amphetamine as a raw material, first protecting the imine with a substituent 1, then placing a substituent 2 at the para position of the phenoxy group, then replacing the substituent 2 with F-18, and then removing the substituent 1 to obtain 3-(4-fluoro[ 18 F] phenoxy)-N-methyl-amphetamine. Substituent 1 can be selected from one of alkoxycarbonyl, acyl, and alkyl groups; for example, one of tert-butyloxycarbonyl, fluorenylmethyloxycarbonyl, benzyloxycarbonyl, allyloxycarbonyl, trifluoroacetyl, phthaloyl, benzyl, p-methoxybenzyl, 2,4-dimethoxybenzyl, trityl, and trimethylsilylethoxymethyl groups.

[0046] In some specific embodiments of the present invention, the preparation method adopts the following synthetic route:

[0047]

[0048] And includes the following steps:

[0049] (1) reacting 3-phenoxy-N-methyl-amphetamine (compound 1) with Boc2O in a solvent, and post-treating the reaction product to obtain compound 2;

[0050] (2) reacting compound 2 with 4-phenolboronic acid pinacol ester in the presence of a catalyst, and post-treating the reaction product to obtain compound 3;

[0051] (3) Compound 3 is subjected to radiochemical labeling reaction, and the reaction product is post-treated to obtain 18 F-labeled compound 4;

[0052] (4) Compound 4 is hydrolyzed to remove the Boc group, and the reaction product is purified to obtain.

[0053] In the above step (1), the reaction of compound 1 and Boc2O is catalyzed by a basic catalyst, which can be one of triethylamine, pyridine, and triethylenediamine. The temperature needs to be controlled below 10°C, preferably 0-5°C.

[0054] In the above step (2), the catalyst is an azodicarboxylic acid ester compound and an organophosphorus compound; the azodicarboxylic acid ester compound can be diisopropyl azodicarboxylate, diethyl azodicarboxylate, dimethyl azodicarboxylate, di-tert-butyl azodicarboxylate, dibenzyl azodicarboxylate, bis(trichloroethyl) azodicarboxylate, etc.; the organophosphorus compound can be triphenylphosphine, tributylphosphine, tri-tert-butylphosphine, etc.

[0055] In the above step (3), the 18 The preparation method of K222 / K2CO3 solution comprises:

[0056] 1) Using a cyclotron, fill the target with water, adjust the beam current to 25 / 100μA, the target pressure to 20-35bar, and bombard 18 F / H2 18 O mixture;

[0057] 2) 18 F / H2 18 The O mixture is pushed through the QMA column by helium gas to 18 F was adsorbed on the QMA column;

[0058] 3) Through K222 / K2CO3 solution 18 F was eluted from the QMA column to obtain.

[0059] In step (4), the Boc group can be hydrolyzed in various ways, such as using a 5M HCl-10% EtOH solution, a 5M HCl-dioxane solution, TFA, or 50% TFA (TFA / dichloromethane volume ratio of 1:1). The hydrolysis temperature can range from 50°C to 110°C. For example, the hydrolysis temperature when catalyzed by a 5M HCl-10% EtOH solution is preferably controlled at 90°C to 105°C.

[0060] The K222 / K2CO3 solution is prepared by mixing amino polyether: potassium carbonate: water: acetonitrile in a ratio of 22 mg: 4 mg: 300 μl: 300 μl.

[0061] Furthermore, in the description of the present invention, it should be noted that, if specific conditions are not specified in the examples, the experiments were carried out according to conventional conditions or the conditions recommended by the manufacturer. Reagents or instruments used without specifying the manufacturer are all conventional products that can be purchased commercially.

[0062] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, which are merely examples of the present invention and are not intended to be limiting.

[0063] Example 1

[0064] This example provides 3-(4-fluoro[ 18 F] phenoxy)-N-methyl-amphetamine preparation method, according to the above-mentioned synthetic route, specifically comprises the following steps:

[0065] (1) In a 500ml three-necked flask, add compound 1 (22.7g, 0.1mol) and 200ml of acetonitrile. Cool to 5°C in an ice bath, add 54.5g (0.25mol) of Boc2O, dissolve 1ml of triethylamine in 10ml of acetonitrile, and slowly drip into the acetonitrile solution of compound 1. Keep the temperature below 10°C during the addition. After the addition is complete, continue stirring at room temperature for 3 hours. Remove the acetonitrile by vacuum distillation to obtain an oily substance. Dissolve it in 100ml of dichloromethane, stir thoroughly with 50ml of water, let it stand for 10min, separate the aqueous layer, and wash the dichloromethane layer 5 times. Finally, add anhydrous sodium sulfate and 1g of activated carbon to the dichloromethane solution, stir for 30min, filter, and concentrate under reduced pressure to obtain compound 2.

[0066] (2) Compound 2 was dissolved in 100 ml of tetrahydrofuran, and 20.2 g (0.1 mol) of diisopropyl azodicarboxylate DIAD, 26.2 g (0.1 mol) of triphenylphosphine, and 22 g (0.1 mol) of 4-phenolboronic acid pinacol ester were added. The mixture was refluxed for 5 reaction hours, and the tetrahydrofuran was removed by concentrating under reduced pressure. 100 ml of dichloromethane was added to dissolve the mixture, and 50 ml of water was stirred and mixed thoroughly. The mixture was allowed to stand for 10 minutes, and the aqueous layer was separated. The dichloromethane layer was washed 5 times. Finally, 1 g of anhydrous sodium sulfate and 1 g of activated carbon were added to the dichloromethane solution, and the mixture was stirred for 30 minutes. The mixture was filtered and concentrated under reduced pressure to an oily state. 50 ml of acetonitrile was added to dissolve the mixture, and the mixture was concentrated under reduced pressure to dryness to obtain a colorless oily substance, namely compound 3. The NMR and mass spectra of compound 3 are shown as follows: Figure 1 and Figure 2 As shown, the specific results are:

[0067] 1H NMR(400MHz,Chloroform-d)δ7.62(d,J=8.6Hz,2H),7.35-7.26(m,4H),7.22(d,J=5.2Hz,1H),6.84-6.76(m,2H),5.16(dd,J=8.6,4.3Hz,1H) ,3.39(t,J=6.4Hz,2H),2.82(s,3H),2.08(ddd,J=9.6,7.2,3.2Hz,2H),1.39(dd,J=12.0,5.1Hz,9H),1.28(d,J=2.2Hz,12H); [M+Na] 490.37.

[0068] 1.2 / 3.0 ml of target water was added to the liquid target (IBA NirtaR18F Liquid Target), and a cyclotron (IBA Cyclonton18 / 9) was used. The beam current was adjusted to 25 / 100 μA and the target pressure was adjusted to 20-35 bar. The 18F / H218O mixture was bombarded. The mixture was pushed by helium and flowed through the QMA column. 18 F is adsorbed on it.

[0069] Elute F-18 from the QMA with 0.6 ml of K₂₂₂ / K₂CO₃ into a 5 ml reaction flask. Remove water at 125°C. Once the liquid has largely disappeared, add 1 ml of ACN and dehydrate once at 110°C. Add a solution of compound 3 / Cu(OTf)₂ / Py / DMSO (1 mg / 28 mg / 26 mg / 1 ml) and react at 110°C for 45 min. Add 7 ml of water, apply to a C₁₂ column, and wash with 10 ml of water. Elute with 2 ml of EtOH into the reaction flask and remove ethanol at 100°C for 10 min. Add 1 ml of a 5 M HCl / 10% EtOH solution and hydrolyze at 80°C for 15 min. Add 2 ml of 60% EtOH and mix.

[0070] The crude product was injected into the HPLC quantitative loop, with 60% ethanol as the mobile phase, the flow rate was 2 ml / min, and the C18 column (5 μm*10 mm*150 mm, Innoval ODS-2) was used. The main peak eluate was collected, diluted with water at a ratio of 1:6, and sterilized by filtration with a 0.22 μm filter to obtain the final product 3-(4-fluoro[ 18 F] phenoxy)-N-methyl-amphetamine. The reference substance used was F19-FX, and its nuclear magnetic resonance and mass spectrometry were as follows: Figure 3 、 Figure 4 As shown, F19-FX was obtained by outsourcing and is a commercially available product. The HPLC positioning of the product prepared in this example and the reference substance is as follows Figure 5 shown.

[0071] Example 2

[0072] This example provides the 3-(4-fluoro[ 18 F] phenoxy)-N-methyl-amphetamine as a PET imaging agent, as shown in the following examples:

[0073] Cynomolgus monkeys (commercially available) were used as imaging animals and injected intravenously with 0.2 mCi / kg 18 F-FX. Imaging results are shown in Figure 6 As shown, Figure A, Figure B, and Figure C can all be clearly displayed 18 F-FX accumulates in the limbic system of the brain, which is consistent with the distribution of 5-HT transporters.

[0074] Therefore, 3-(4-fluoro[ 18 F]phenoxy)-N-methyl-amphetamine is expected to be developed into a tracer for clinical use as a PET imaging agent. It can also be prepared into various detection tracer products, such as kits, to assess the severity of depression. In addition, 3-(4-fluoro[ 18 F]phenoxy)-N-methyl-amphetamine active ingredient 18 F-FX has an extremely low chemical content and does not trigger any physiological reactions when prepared as a PET imaging agent. It simply automatically recognizes and binds to the serotonin transporter. Using PETCT imaging technology, the density, distribution, and binding capacity of the serotonin transporter can be visually observed in the image. This allows for direct understanding of the severity of various diseases.

[0075] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. 3-(4-fluoro[ 18 F] phenoxy)-N-methyl-amphetamine in the preparation of F-18 labeled 5-HT transporter tracer, the 3-(4-fluoro[ 18 The chemical structural formula of [F] phenoxy)-N-methyl-amphetamine is:

2. An F-18 labeled 5-HT transporter tracer, characterized in that The tracer includes 3-(4-fluoro[ 18 F]phenoxy)-N-methyl-amphetamine.

3. The method for preparing an F-18 labeled 5-HT transporter tracer according to claim 2, characterized in that: The preparation method includes 3-(4-fluoro[ 18 F] phenoxy)-N-methyl-amphetamine synthesis; The 3-(4-fluoro[ 18 The synthesis of 3-(4-fluoro-[F]phenoxy)-N-methyl-amphetamine comprises: using 3-phenoxy-N-methyl-amphetamine as a raw material, first protecting the imine with a substituent group 1, then placing a substituent group 2 at the para position of the phenoxy group, then replacing the substituent group 2 with F-18, and then removing the substituent group 1 to obtain 3-(4-fluoro-[ 18 F]phenoxy)-N-methyl-amphetamine; The substituent is selected from one of alkoxycarbonyl, acyl and alkyl; Preferably, the substituent is selected from one of tert-butyloxycarbonyl, fluorenylmethyloxycarbonyl, benzyloxycarbonyl, allyloxycarbonyl, trifluoroacetyl, phthaloyl, benzyl, p-methoxybenzyl, 2,4-dimethoxybenzyl, trityl and trimethylsilylethoxymethyl.

4. The preparation method according to claim 3, characterized in that The 3-(4-fluoro[ 18 F] phenoxy)-N-methyl-amphetamine synthesis adopts the following route: And includes the following steps: Step 1, reacting compound 1 with Boc2O in the presence of a catalyst to obtain compound 2; Step 2, reacting compound 2 with 4-phenol boronic acid pinacol ester in the presence of a second catalyst to obtain compound 3; Step 3, compound 3 is reacted with 18 The medium is subjected to radiochemical labeling reaction to obtain 18 F-labeled compound 4; Step 4, remove the Boc group from compound 4 to obtain 3-(4-fluoro[ 18 F]phenoxy)-N-methyl-amphetamine.

5. The preparation method according to claim 4, characterized in that In step 1, the molar ratio of compound 1 to Boc2O is 1:2-3; and / or, the catalyst 1 is selected from one of triethylamine, pyridine, and triethylenediamine, preferably triethylamine; and / or, the reaction temperature does not exceed 10°C.

6. The preparation method according to claim 4, characterized in that In the step 2, the amount of 4-phenol boronic acid pinacol ester added is calculated based on a molar ratio of 0.9 to 1.1:1 to compound 1; and / or the molar ratio of catalyst 2 to 4-phenol boronic acid pinacol ester is 1.5 to 2:1; and / or the reaction temperature is 60 to 65° C.; Preferably, the second catalyst is an azodicarboxylic acid ester compound and an organophosphorus compound; More preferably, the azodicarboxylic acid ester compound is at least one selected from diisopropyl azodicarboxylate, diethyl azodicarboxylate, dimethyl azodicarboxylate, di-tert-butyl azodicarboxylate, dibenzyl azodicarboxylate, and bis(trichloroethyl) azodicarboxylate; and / or the organophosphorus compound is at least one selected from triphenylphosphine, tributylphosphine, and tri-tert-butylphosphine.

7. The preparation method according to claim 4, characterized in that The step 3 includes: Step 3-1, the 18 The K222 / K2CO3 solution is dehydrated; Step 3-2, remove the water containing F 18 The K222 / K2CO3 solution reacted with compound 3 at 100-110°C under the catalysis of Cu(OTf)2 and pyridine; Preferably, the mass ratio of compound 3 to Cu(OTf)2 is 1:10-40; and / or, Preferably, the mass ratio of Cu(OTf)2 to pyridine is 1 to 2:1; and / or, Preferably, the reaction solvent in step 3-2 is DMSO.

8. The preparation method according to claim 4, characterized in that In step 4, an acidic reagent is used to remove the Boc group from compound 4; preferably, the reaction temperature is 50-100°C, more preferably 70-90°C.

9. Use of the F-18 labeled 5-HT transporter tracer according to claim 2 in the preparation of a PET imaging agent.

10. Use of the F-18 labeled 5-HT transporter tracer according to claim 2 in the preparation of a product for assessing the severity of depression.

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