JPH0797361A - New chelate-forming compound and its use - Google Patents

Abstract

PURPOSE:To obtain the subject compound which is useful as an imaging agent for mammalian brains because of its stability, prompt incorporation into the brain after application, low blood level and excellent clearance. CONSTITUTION:A compound of formula I (R is H, a 1-8C (amino)alkyl, a 2-16C alkoxyalkyl, a 4-13C alkyl-cycloalkyl, a 2-5C alkenyl, a 2-5 alkinyl) or its salt, for example, 1-N-(2-mercapto-2-methylpropyl)-2-N'-[2-(S-methylthio) phenyl]diamino-ethane. The compound of formula I is obtained by using 2- mercaptoaniline as a starting substance to subject it to reaction with an alkyl bromide or allyl bromide, allowing the product to react with 1-amino-2- bromoethane to form into the compound of formula II followed by reaction of the product with a compound of formula III in the presence of sodium hydrogen cyanoborate.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel chelate-forming compound or a salt thereof, a radiometal-labeled complex derived from the compound, and an imaging of the brain of mammals including humans containing the complex. Relates to a radioactive diagnostic agent useful for.

[0002]

2. Description of the Related Art A complex labeled with a radioactive metal has been used as an imaging agent for the purpose of diagnostic imaging. The radioactive metals used for these labels are
It must be one that emits radiation that penetrates tissues and organs in the body, and radioactive isotopes that emit gamma ray, X-ray, or positron radiation have been used.

Preferred radioactive isotopes satisfying these conditions are iodine-123 and technetium-99.
You can give m and so on. In particular, technetium-9
The energy of the emitted gamma rays is 140 KeV at 9 m.
Suitable for scintigram imaging in a radiation imaging device that can be used for general purposes, in the nuclear medicine field for the purpose of visualization of specific organs, detection of specific diseases and dynamic examination,
It has a suitable half-life of 6 hours, and has the advantage that it can be easily and inexpensively obtained due to the widespread use of generators, and thus it can be said to be a particularly preferable radioisotope.

However, most of the technetium-99m labeled complexes used as radiodiagnostic agents for in vivo imaging have a positive or negative charge. It is known that such a charged complex cannot penetrate the blood-brain barrier when the brain is the target organ. Moreover, some of these compounds have the problem that they are prone to decomposition when complexed with a radioactive metal and when administered in vivo.

Japanese Unexamined Patent Publication (Kokai) No. 61-143351 discloses a complex of technetium-99m and propylamine oxime, which is a requirement useful as a radiological imaging agent for cerebral blood flow imaging, and sufficient uptake into the brain. Alternatively, it is said to have a sufficient retention time in the brain. However, the compound is relatively fast converted to a polar compound after preparation, and in intravenous injection by bolus administration,
There were problems such as high blood levels and relatively slow clearance from blood. Therefore, there is room for improvement in the stability of the prepared complex and in blood, and in the case where the brain is the target organ, the blood level which is the main background.

In order to solve these problems, studies have been conducted on ligands which are neutral in charge, form a highly lipophilic and stable complex. HFKung et al. (J. Nucl. Med., No. 25
Vol., 326-332, 1984) confirmed that the diaminedithiol derivative and its technetium-99m complex were neutral, and when these compounds were administered to rats, 2% ID was obtained 2 minutes after the administration. Although the above accumulation in the brain is observed, it is reported that it is washed out from the brain over time.

JP-A 61-5056 and JP-A 62-96460 disclose diaminedithiol for the purpose of retaining an electric charge in the brain due to the difference in pH between blood and brain. A compound having a basic skeleton and a tertiary amine introduced into a side chain is described. This technique resulted in some improvements in the technique of retaining the compound in the brain. Further, JP-A-63-295549 describes a method of introducing an ester group into a side chain, and describes that the compound stays in the brain. It is believed that this is because the esterase in the brain hydrolyzes the ester to convert the neutral complex into a negatively charged complex.

[0008] Nathan Bryson et al. Reported that a neutral technetium-99 complex can be obtained by modifying either one of thiols among diamidedithiols which are N ₂ S ₂ type ligands. (Inorg.Chem., Volume 27, 21
54-2161, 1988). However, all of them are neutral in electric charge, and there is a drawback that it is difficult to obtain a highly lipophilic and stable complex that satisfies all of the complex formation and the blood level after biological administration.

[0009]

DISCLOSURE OF THE INVENTION According to the present invention, a complex composed of such a conventional ligand and a radioactive metal such as technetium-99m lacks stability after preparation and has a high blood level after in vivo administration and is favorable. In view of the fact that it is difficult to obtain various contrasts, the stability of the complex after preparation is high, it is taken into the brain promptly after administration, and it is retained for an appropriate time, the blood flow level after in vivo administration is low, and the clearance is also high. It is an object of the present invention to provide a chelate-forming compound useful for imaging the brain of mammals including humans, a complex comprising the compound and a radioactive metal, and a radioactive diagnostic agent containing the complex. .

[Means for Solving the Problems]

That is, the present invention is

[Chemical 2] A chelate-forming compound having a structure represented by and a salt thereof (in the formula 1, R is hydrogen, an alkyl group having 1 to 8 carbon atoms, an aminoalkyl group having 1 to 8 carbon atoms, and 2 to 2 carbon atoms).
It is a 16-alkoxy alkyl group, a C4-C13 alkyl cyclic alkyl group, a C2-C5 alkenyl group, or a C2-C5 alkynyl group. ) Is a complex comprising the compound and a radioactive metal, and a radioactive diagnostic agent containing the complex.

The alkyl group in the formula 1 is a straight or branched chain saturated hydrocarbon having 1 to 8 carbon atoms such as a methyl group, an isopropyl group, a butyl group, an isobutyl group and a pentyl group, and preferably, It is a straight chain or branched chain saturated hydrocarbon having 1 to 5 carbon atoms, and particularly preferably a straight chain or branched chain saturated hydrocarbon having 1 to 3 carbon atoms. The alkenyl group has 2 to 2 carbon atoms such as an ethenyl group and a 2-propenyl group.
It is a straight-chain or branched-chain unsaturated hydrocarbon having 5 carbon atoms, preferably a straight-chain or branched-chain unsaturated hydrocarbon having 2 to 4 carbon atoms. The alkynyl group is a straight chain or branched chain unsaturated hydrocarbon having an acetylene triple bond having 2 to 5 carbon atoms, such as a 2-propynyl group. The alkyl cyclic alkyl group is a group composed of an alkyl group having 1 to 5 carbon atoms to which a saturated cyclic hydrocarbon group having 3 to 8 carbon atoms such as a cyclopropylmethyl group and a cyclopentylpropyl group is bonded. The alkoxyalkyl group is represented by -X-O-Y, wherein X and Y are linear and branched saturated hydrocarbons having 1 to 8 carbon atoms, and preferably linear and C 1 to 3 carbon atoms. It is a branched chain saturated hydrocarbon. The aminoalkyl group is -Z-N
It is represented by H ₂ , and Z is a linear or branched saturated hydrocarbon having 1 to 8 carbon atoms, preferably a linear or branched saturated hydrocarbon having 1 to 3 carbon atoms.

The compound of formula 1 can be salted,
Such salts include hydrochlorides, acetates and the like. Further, the compound can be reacted with a radioactive metal to obtain a radioactive metal complex. In particular, as a radiopharmaceutical, technetium-99 which is a preferred radioisotope
The m-labeled complex was prepared by using sodium pertechnetate solution and Formula 1
It can be obtained by reacting the compound represented by the formula (1) with a reducing agent. This technetium-99
The m-labeled complex is

[0013]

[Chemical 3] It is considered to be indicated by.

In the formula 2, R is hydrogen and has 1 to 8 carbon atoms.
Alkyl group, C1-C8 aminoalkyl group, C2-C16 alkoxyalkyl group, C4-C13 alkyl cyclic alkyl group, C2-C5 alkenyl group or C2-C5 It is an alkynyl group.

Since the pharmaceutically acceptable complex of the chelate-forming compound of the present invention and its radioactive metal such as technetium-99m is a charge-neutral complex having high lipophilicity, mammals including humans. It can be taken up in large amounts in the brain of animals to achieve rapid dispersion of radioactive substances. These compounds and their complexes are stable for up to 24 hours after the preparation of the complex, and further, they are stable in metabolism after being administered in vivo in commonly used parenteral administration such as intravenous injection by bolus administration. It is also excellent in that it does not decompose even at high radioactivity levels of 100 mCi or more per single preparation. In addition, it has a desirable characteristic that it has a constant local distribution in the brain, is suitable for scintigram imaging, is retained in the brain for 1 hour or more immediately after administration, has a high brain / blood ratio, and is then excreted outside the body. Therefore, it also has excellent characteristics to solve the conventional problems, such as being able to make a diagnosis using a radiation imaging device that can be used for general purposes.

The above mentioned properties mean that the compound of formula 1 and its pharmaceutically acceptable complex of a radioactive metal such as technetium-99m are useful as radiodiagnostic agents for imaging the brain. There is. Below are shown typical synthetic routes and methods of preparation of compounds of Formula 1 and Formula 2.

[0017]

[Figure 1]

[0018]

[Fig. 2]

[0019]

[Figure 3]

The compound of formula 1 is synthesized by subjecting 2-mercaptoaniline of compound 1 in FIG. 1, which is a starting material, to a selective nucleophilic substitution reaction with alkyl bromide or allyl bromide under weakly basic conditions. Extraction gives compound 3, an intermediate compound of the compound of formula 1. Then, the compound 3 obtained and the compound 5 obtained by hydrolyzing 2-mercapto-2-methylpropanal ethylenedioxyacetal are added in the presence of sodium cyanoborohydride (hereinafter referred to as NaBH ₃ CN). Then, the desired compound of formula 1 is obtained by the condensation reaction. The compound of formula 1 can also be obtained by deprotecting compound 6 after the compound 6 is obtained by the condensation reaction of compound 3 and compound 4 having a protected thiol in the presence of NaBH ₃ CN.

The compound of formula 1 thus obtained is reacted with a sodium pertechnetate solution in the presence of a reducing agent such as stannous chloride or sodium dithionite to form a complex of formula 2 Obtainable. At this time,
Unreacted pertechnetate and insoluble radioactive impurities can be removed by a membrane filter, liquid chromatography (HPLC), or the like.

The compound of formula 1 is also prepared from a disulfide-bonded dimer represented by formula 3 by reacting with pertechnetate in the presence of a reducing agent to prepare a monomer. It is possible to obtain the same complex. Figure 4
The method for synthesizing the dimer is described in.

[0023]

[Figure 4]

The compound of formula 3 represented by compound 6 in FIG.
By hydrolyzing 2-2′-dithiobis (2-methylpropanal) bisethylenedioxyacetal of compound 4 in FIG. 4, compound 5 in FIG. 4 is obtained, and then obtained compound 5 and in FIG. Compound 3 can be synthesized by a condensation reaction route in the presence of NaBH ₃ CN.

The compounds of the present invention are macrogol or 2
After being made into an aqueous solution using a solubilizing agent such as -hydroxy-β-cyclodextrin (HPCD), a conventional reducing agent having an appropriate redox potential which is pharmaceutically acceptable (for example, stannous chloride, suboxide Sodium dithionate, sodium borohydride), stabilizers (eg ascorbic acid, p-aminobenzoic acid), excipients (eg D-
Mannitol), accelerators that help improve the radiochemical purity of the product (eg, citric acid, tartaric acid, malonic acid) and the like, and can also be provided in the form of a ready-to-use kit.

The radioactive diagnostic agent of the present invention can be administered by a commonly used parenteral means such as intravenous injection by bolus administration, and its dose is the weight of the patient, the age and appropriate radiation. The amount of radioactivity considered to be imageable is determined in consideration of various conditions of the imaging device and the like. When targeting humans, usually 5 to 30
A range of mCi is preferred. Hereinafter, the present invention will be described more specifically with reference to Examples.

[0027]

【Example】

Example 1 Synthesis of N- [2- (S-methylthio) phenyl] -1,2-diaminoethane. Boc-glycine 1.3 g (7.2 mmol) and 2- (S-methylmercapto) aniline 1.0 g (7.2 mmol) were dissolved in 70 ml of dichloromethane in an ice bath,
1.5 g of 1-ethyl-3- (3′-dimethylaminopropyl) carbodiimide-hydrochloric acid (hereinafter referred to as WSC)
(7.9 mmol) was added, and the mixture was stirred for 1 hour, then water 10 was added.
It was washed twice with 0 ml. The organic layer was concentrated and then isolated by silica gel column chromatography (eluent: dichloromethane / methanol = 100/2) to give 2.4 g of a yellow oily substance.
(8.0 mmol) was obtained.

2.3 g (7.7 mmol) of this compound was added to 100 m of tetrahydrofuran (hereinafter referred to as THF).
Lithium aluminum hydride (hereinafter LA
It is called H. ) 0.88 g (23 mmol) was added, and the mixture was heated under reflux for 1 hour and cooled with ice, and ethyl acetate was added until foaming stopped. The insoluble matter was removed by filtration, the filtrate was concentrated under reduced pressure, and extracted twice with ether. The organic layer was concentrated and then isolated by silica gel column chromatography (eluent: hexane / ethyl acetate = 2/1) to give 1.7 g (6.0 m) of a yellow oil.
mol) was obtained. 1.7 g (6.0 mmo of this compound
l) was dissolved in 20 ml of ethyl acetate in an ice bath, a solution of 4N hydrochloric acid in ethyl acetate was added, and the mixture was stirred for 5 minutes. After adding 25 ml of 4N sodium hydroxide to make it basic, the mixture was extracted twice with ethyl acetate. After this organic layer was concentrated, it was isolated by silica gel column chromatography (eluent: chloroform), and 1.1 g of N- [2- (S-methylthio) phenyl] -1,2-diaminoethane (6. 0m
mol) was obtained.

(Example 2) 1-N- (2-mercapto-2-methylpropyl) -2
Synthesis of -N '-[2- (S-methylthio) phenyl] diaminoethane. 2-mercapto-2-methylpropanal ethylenedioxyacetal 0.15 g (1.0 mmol) 0.5N
After refluxing for 4 hours in 3.0 ml of hydrochloric acid and 3.0 ml of THF, the mixture was extracted with ether and the solvent was distilled off. Example 1 in the residue
N- [2- (S-methylthio) phenyl] -1,2-
Diaminoethane 0.21 g (1.0 mmol), acetic acid 0.060 g (2.0 mmol) and methanol 80
ml was added, and 30 minutes later, 0.063 g of NaBH ₃ CN was added.
(1.0 mmol) was added. After 12 hours, the product was purified by silica gel dry column chromatography (eluent: chloroform / isopropyl = 25/1) to obtain 0.076 g (0.28 mmol) of a pale yellow oily substance.

The attribution of proton NMR of this compound at 270 MHz was as follows. 1.40 pp
m (6H, s), 2.32ppm (3H, s), 2.6
7 ppm (2H, s), 2.95 to 3.05 ppm (2
H, m), 3.20 to 3.30 ppm (2H, m),
5.40 ppm (1 H, br s), 6.60 to 7.4
0 ppm (4H, m). In addition, a peak of M ⁺ 270 was observed in mass spectrometry.

(Example 3) N- [2- (S-propylthio) phenyl] -1,2-
Synthesis of diaminoethane. 5.0 g (40 mmol) of 2-mercaptoaniline and 6.8 g (40 mmol) of propyl iodide were added to 50 m of DMF.
It was dissolved in 1 and stirred for 24 hours. Ethyl acetate 1 in the reaction solution
00 ml was added and this was washed with 100 ml of water. The ethyl acetate layer was then concentrated under reduced pressure and subjected to silica gel column chromatography (eluent: benzene / ethyl acetate = 10).
/ (1) to obtain 2- (S-propylthio) aniline (2.2 g, 13 mmol). 2- (S-propylthio) aniline 1.0 g (6.0 mmol)
Bromoethylammonium bromide 1.2 g (6.0
mmol), and N- by the method described in Example 1.
0.24 g (1.1 mmol) of [2- (S-propylthio) phenyl] -1,2-diaminoethane was obtained.

(Example 4) 1-N- (2-mercapto-2-methylpropyl) -2
Synthesis of -N '-[2- (S-propylthio) phenyl] diaminoethane. N- [2- (S-propylthio) phenyl] of Example 3
-1,2-diaminoethane 0.20 g (0.92 mmo
To l), 0.10 g (0.96 mmol) of 2-mercapto-2-methylpropanal was added and dissolved in 1 ml of acetic acid. Condensation and reduction are carried out according to the method of Example 2 to obtain the desired product, 1-N- (2-mercapto-2-methylpropyl)-.
0.056 g (0.23 mmol) of 2-N '-[2- (S-propylthio) phenyl] diaminoethane was obtained.
When this compound was analyzed by silica gel thin layer chromatography (thin layer plate: silica gel 60, developing solvent: chloroform / isopropanol = 25/1), the Rf value was about 0.
A single spot was seen in 3.

Example 5 N- [2- (S-isopropylthio) phenyl] -1,
Synthesis of 2-diaminoethane. 2-mercaptoaniline 5.0 g (40 mmol) and 2
-Bromopropane 4.9 g (40 mmol) in DMF5
It was dissolved in 0 ml and stirred at 80 ° C for 21 hours. 100 ml of ethyl acetate was added to the reaction solution, and this was mixed with 100 ml of water to 3 times.
Washed twice. The organic layer was concentrated under reduced pressure and then purified by silica gel column chromatography (eluent: benzene / ethyl acetate = 20/1) to obtain 1.2 g (6.9 mmol) of 2- (S-isopropylthio) aniline. . 1.1 g of this 2- (S-isopropylthio) aniline (6.
2-bromoethylammonium bromide 1.4 g (6.5 mmol) was dissolved in DMF 20 ml, and the mixture was stirred in an oil bath at 80 ° C. for 21 hours to obtain ethyl acetate 1
It was washed 3 times with 00 ml. The organic layer was concentrated under reduced pressure and then isolated by silica gel column chromatography (eluent: chloroform / ethanol = 100/3) to obtain N- [2- (S-isopropylthio) phenyl] -1,2 as a yellow oily substance. -0.26 g of diaminoethane (1.2 mm
ol) was obtained.

(Example 6) 1-N- (2-mercapto-2-methylpropyl) -2
Synthesis of -N '-[2- (S-isopropylthio) phenyl] diaminoethane (disulfide linked dimer). 2,2′-dithiobis (2-methylpropanal) bisethylenedioxyacetal 0.53 g (1.8 mmo
l) is dissolved in 5.0 ml of THF and 1 m hydrochloric acid 6.0 m
1 was added and the mixture was heated under reflux for 50 minutes. After air cooling, ether 2
It was extracted twice with 0 ml, and the organic layer was concentrated under reduced pressure. This residue was dissolved in 20 ml of methanol, 0.5 ml of acetic acid was added, and then 0.82 g of N- [2- (S-isopropylthio) phenyl] -1,2-diaminoethane obtained in Example 5.
(3.0 mmol) was dissolved in 10 ml of methanol and added, and the mixture was stirred at room temperature for 15 minutes. After that, NaBH ₃ CN
0.25 g (3.9 mmol) was added, and the mixture was stirred at room temperature for 20 hours. After the solvent was distilled off, water was added to the residue and the mixture was extracted with chloroform. The organic layer was concentrated under reduced pressure, then isolated by silica gel column chromatography (eluent: hexane / ethyl acetate = 5/1), and further preparative silica gel thin layer chromatography (thin layer plate: silica gel 60F254, developing solvent: CHCl. ₃ / EtOH = 60/1) isolated and purified, 0.10 g (0.16 mmol) of pale yellow red oily substance
Got

The attribution of proton NMR of this compound at 270 MHz was as follows. 1.22 pp
m (6H, d, J = 7Hz; -CH 3 × 2), 1.31
_{ppm (6H, s, -CH 3} × 2), 1.45ppm
(1H, br s; -NH-), 2.62 ppm (2
_{H, s; -CH 2 -)} , 2.91ppm (2H, t; J
_{= 5Hz; -CH 2 -),} 3.11~3.44ppm
(3H, m; ≡CH, -CH 2 -), 5.6ppm (1
H, br s; -PhNH), 6.57 to 6.62 pp
m (2H, m; aroma), 7.20 ppm (1H,
td, J = 8 Hz, 1 Hz; aroma), 7.37p
pm (1H, dd, J = 8Hz, 1Hz; arom
a).

Example 7 N- [2- (S-2'-propenylthio) phenyl]-
Synthesis of 1,2-diaminoethane. 2.5 g (20 mmol) of 2-mercaptoaniline 3
-Iodo-1-propene (3.4 g, 20 mmol) was added, DMF (20 ml) was added, and the mixture was stirred at room temperature for 4 hours.
Chloroform was added to the reaction solution, which was washed with water. The obtained organic layer was concentrated under reduced pressure and subjected to silica gel column chromatography (eluent: hexane / ethyl acetate = 20 /
It refine | purified by 1) and obtained 1.6 g (9.6 mmol) of 2- (S-2'-propenylthio) aniline. This 2- (S
-2'-propenyl mercapto) aniline 0.33 g
(2.0 mmol) was dissolved in 5 ml of DMF, and 0.20 g of 2-bromoethylammonium bromide (1.0 m
mol) was added, and N- [2- (S-2'-propenylthio) phenyl] -1,2-diaminoethane (0.10 g, 0.50 m) was obtained as a yellow oil by the method described in Example 5.
mol) was obtained.

(Example 8) 1-N- (2-mercapto-2-methylpropyl) -2
Synthesis of -N '-[2- (S-2'-propenylthio) phenyl] diaminoethane. 2-Mercapto-2-methylpropanal ethylenedioxyacetal 0.52 g (3.5 mmol) in THF
5.9 ml and 7.5 ml of 0.5N hydrochloric acid were added, and 1.
Refluxed for 5 hours. The reaction solution was extracted with ether, the solvent was distilled off, and the mixture was stirred at room temperature to give N- [2- (S-2 ′) of Example 7.
-Propenylthio) phenyl] -1,2-diaminoethane (0.61 g, 2.9 mmol) was added to methanol (10 ml).
The solution dissolved in was added to 0.75 ml of acetic acid (13 mmo
l) was added. After 30 minutes, 0.43 g of NaBH ₃ CN
(6.8 mmol) and 5.0 ml of methanol were added, and the mixture was stirred at room temperature for 70 hours. The reaction solution was adjusted to pH 3 with 0.5N hydrochloric acid, the solvent was distilled off, water was added to the residue, and the mixture was extracted with chloroform. The organic layer was dried over anhydrous sodium sulfate to obtain 0.68 g of a yellow oily substance. This organic layer extract was subjected to preparative silica gel thin layer chromatography (thin layer plate: silica gel 60F254, developing solvent: hexane / ethyl acetate = 1/1) to separate a band having an Rf value of 0.27. Further, it was subjected to preparative silica gel thin layer chromatography (thin layer plate: silica gel 60F254, developing solvent: chloroform / ethanol = 20/1), and an Rf value of 0.5.
The band of 7 was separated and purified, and 0.030 g of a yellow oily substance was obtained.
(0.10 mmol) was obtained.

The attribution of proton NMR of this compound at 270 MHz was as follows. 1.39ppm
_{(6H, s, (CH 3} ) 2 -), 2.66ppm (2
_{H, s, -NHCH 2 C (} CH 3) 2 -), 2.99p
pm (2H, t, J = 6Hz, -SCH 2 CH =),
3.25ppm (2H, br s, -CH 2 CH 2 NH
−) 3.33 ppm (2H, d, J = 7 Hz, PhN
HCH ₂ −) 4.96 ppm (1H, d, J = 6H
_{z, -CH = CH 2),} 4.97ppm (1H, d, J
_{= 6Hz, -CH = CH 2)} , 5.54ppm (1H,
brs, -NH-), 5.82 ppm (1H, m,-
CH = CH ₂ ), 6.62 ppm (2H, d, J = 8H
z, aroma H), 7.20 ppm (1 H, td,
J = 8Hz, 2Hz, aroma H), 7.37pp
m (1H, dd, J = 8Hz, 2Hz, aroma
H).

Example 9 N- [2- (S-2'-propynylthio) phenyl]-
Synthesis of 1,2-diaminoethane. 2.6 g (20 mmol) of 2-mercaptoaniline D
Dissolve in 1 ml of MF and stir in ice while stirring 3-
2.4 g (20 mmol) of bromo-1-propyne was added dropwise. After the dropping, the reaction liquid with increased viscosity was dissolved in chloroform. Chloroform was washed with water and then distilled off.
-(S-2'-propynylthio) aniline 3.6 g (2
2 mmol) was obtained. 2.2 g (11 mmo) of 2-bromoethylammonium bromide was added to 3.2 g (16 mmol) of 2- (S-2′-propynylthio) aniline.
l) was added and N- [2-
2.0 g (12 mmol) of (S-2'-propynylthio) phenyl] -1,2-diaminoethane was obtained.

(Example 10) 1-N- (2-mercapto-2-methylpropyl) -2
Synthesis of -N '-[2- (S-2'-propynylthio) phenyl] diaminoethane. 0.64 g (3.1 of N- [2- (S-2'-propynylthio) phenyl] -1,2-diaminoethane of Example 9
mmol) in 1 ml of methanol and 0.61 g (3.0 mm) of 2-benzoylthio-2-methylpropanal
ol), 1 ml of acetic acid was further added, and the mixture was stirred at room temperature for 1 hour. After that, 0.28 g of NaBH ₃ CN (4.4
mmol) was added, and condensation reduction was performed. After adding water to the reaction solution, the target product was extracted with chloroform. The chloroform was distilled off to obtain 1.4 g (0.93 mmol) of a benzoyl compound. After hydrolyzing by adding an equal amount of sodium hydroxide solution to the benzoyl compound, the liquid property is made acidic and 1-N- (2-mercapto-2- of the final target product is made with chloroform.
Methylpropyl) -2-N '-[2- (S-2'-propylthio) phenyl] diaminoethane 0.059 g
(0.20 mmol) was obtained.

Example 11 Synthesis of N- [2- (S-2'-methoxyethylthio) phenyl] -1,2-diaminoethane. 1 to 3.9 g (31 mmol) of 2-mercaptoaniline
-Chloro-2-methoxyethane 2.9 g (31 mmo
l) was added, and 3.2 g of triethylamine was added with stirring.
(32 mmol) was added. The precipitated crystals were filtered out, dissolved in ether, washed with water to wash the ether layer, and then the ether was distilled off to give the desired 2- (S-2 ′).
-Methoxyethylthio) aniline 3.5 g (19 mmo
l) was obtained. 3.5 g (19 mmol) of this 2- (S-2′-methoxyethylthio) aniline and 2.5 g (12 mmo) of 2-bromoethylammonium bromide.
l) was dissolved in 5 ml of N, N-dimethylacetamide,
By the method shown in Example 1, 1.6 g (7.1 mmol) of N- [2- (S-2'-methoxyethylthio) phenyl] -1,2-diaminoethane was obtained.

(Example 12) 1-N- (2-mercapto-2-methylpropyl) -2
Synthesis of -N '-[2- (S-2'-methoxyethylthio) phenyl] diaminoethane. 1.1 g of N- [2- (S-2'-methoxyethylthio) phenyl] -1,2-diaminoethane obtained in Example 11
(4.9 mmol) was dissolved in a small amount of methanol to give 2-
Benzoylthio-2-methylpropanal 1.0 g (4.
9 mmol) was added and synthesized according to the method shown in Example 10, 1-N- (2- mercapto-2-methylpropyl purposes) -2-N '- [2- ^(S-2' - methoxyethyl Thio) phenyl] diaminoethane 0.068 g (0.
22 mmol) was obtained.

Example 13 Synthesis of N- [2- (S-cyclopropylmethylthio) phenyl] -1,2-diaminoethane. 2-mercaptoaniline 4.6 g (37 mmol) D
It was dissolved in 20 ml of MF, 4.9 g (36 mmol) of bromomethylcyclopropane was added dropwise thereto, and 18
Stir for hours. After distilling off DMF, the product was extracted with ether and purified by silica gel column chromatography (eluent: hexane / ethyl acetate = 25/1) to obtain the desired 2- (cyclopropylmethylthio) aniline 3. 0 g (17 mmol) was obtained. 2.5 g (14 mmol) of 2- (cyclopropylmethylthio) aniline
And 2-bromoethylammonium bromide 1.5
g (7.2 mmol) was dissolved in a small amount of DMF, and N- [2- (S-cyclopropylmethylthio) phenyl] -1,2-diaminoethane (0.1%) was dissolved by the method described in Example 1.
60 g (2.7 mmol) was obtained.

(Example 14) 1-N- (2-mercapto-2-methylpropyl) -2
Synthesis of -N '-[2- (S-cyclopropylmethylthio) phenyl] diaminoethane. N- [2- (S-cyclopropylmethylthio) phenyl] -1,2-diaminoethane 0.50 obtained in Example 13
g (2.3 mmol) was dissolved in a small amount of methanol, and 2
-Mercapto-2-methylpropanal 0.28 g (2.
6 mmol) and then 1 ml of acetic acid was added,
The desired 1-N- (2-mercapto-
2-Methylpropyl) -2-N '-[2- (S-cyclopropylmethylthio) phenyl] diaminoethane 0.0
52 g (0.17 mmol) was obtained.

(Example 15) 1-N- (2-mercapto-2-methylpropyl) -2
Preparation of technetium-99m complex of -N '-[2- (S-methylthio) phenyl] diaminoethane. 1-N- (2-mercapto-2-methylpropyl) -2
-N '-[2- (S-methylthio) phenyl] diaminoethane (hereinafter referred to as ligand-1) was dissolved in ethanol to give a concentration of 0.35 mg / ml. This liquid 1.
To 0 ml, 0.2 ml of 50 mCi / ml sodium pertechnetate injection and 0.1 ml of 0.19 mg / ml stannous chloride solution were added and mixed, and the mixture was allowed to stand at room temperature for about 15 minutes. Then, the prepared solution was filtered through a 0.22 μm membrane filter, and an appropriate amount of physiological saline was added to the filtrate to prepare ligand-1-technetium-99m.
A preparation liquid was prepared. The purity of this prepared solution was analyzed by TLC using silica gel 60 thin layer plate with hexane / ethyl acetate = 1/1 as a developing solvent. The Rf value of the labeled complex was about 0.9 and the purity was 90% or more.

(Example 16) 1-N- (2-mercapto-2-methylpropyl) -2
Preparation of technetium-99m complex of -N '-[2- (S-isopropylthio) phenyl] diaminoethane. 1-N- (2-mercapto-2-methylpropyl) -2
-N '-[2- (S-isopropylthio) phenyl] diaminoethane (hereinafter referred to as ligand-2) was dissolved in a solution prepared by diluting 1N hydrochloric acid with ethanol 200 times,
The concentration was 0.30 mg / ml. To 1 ml of this solution, 0.2 ml of 40 mCi / ml sodium pertechnetate injection solution and 0.1 ml of 0.19 mg / ml stannous chloride were added and mixed, and heated in a steam autoclave at 120 ° C for 20 minutes. . After the mixture is brought to room temperature at room temperature, the prepared solution is filtered through a 0.22 μm membrane filter, and an appropriate amount of physiological saline is added to the filtrate to give 50%.
It was an EtOH solution. The purity of this preparation is hexane /
It was analyzed by TLC using a thin layer plate of silica gel 60 with ethyl acetate = 1/1 as a developing solvent. The Rf value of the labeled complex was about 0.2 and the purity was 80% or more.

Example 17 1-N- (2-mercapto-2-methylpropyl) -2
Preparation of technetium-99m complex of -N '-[2- (S-2'-propenylthio) phenyl] diaminoethane. 1-N- (2-mercapto-2-methylpropyl) -2
-N '-[2- (S-2'-propenylthio) phenyl] diaminoethane (hereinafter referred to as ligand-3) was dissolved in ethanol to give a concentration of 0.38 mg / ml. 0.2 ml and 0.19 m of 30 mCi / ml sodium pertechnetate injection for 1 ml of this solution
0.1 ml of g / ml stannous chloride solution was added and mixed,
It was heated in a steam autoclave at 120 ° C for 15 minutes. After being brought to room temperature at room temperature, the prepared solution was filtered with a 0.22 μm membrane filter, and an appropriate amount of physiological saline was added to the filtrate to obtain a 60% EtOH solution. The purity of this prepared solution was analyzed by TLC using silica gel 60 thin layer plate with hexane / ethyl acetate = 1/1 as a developing solvent. The Rf value of the labeled complex was about 0.5 and the purity was 90% or more.

Example 18 Pharmacokinetics of technetium-99m complex in rat. Ligand-1-technetium-9 prepared in Example 15
75 μl of 9 m preparation, the ligand prepared in Example 16
100 μl of 2-technetium-99m preparation and ligand-3-technetium-99m prepared in Example 17
100 μl of the prepared liquid was anesthetized with thiopentobarbital in advance, and SD female rats (170 to 240 g)
(Body weight) was administered through the tail vein. After the administration, the rats were sacrificed, and the pharmacokinetics of radioactivity after the administration was measured. The results are shown in Table 1, Table 2 and Table 3. All of the labeled substances immediately accumulated in the brain immediately after the administration and showed high brain transferability. After that, the radioactivity is gently washed out of the brain,
The speed was slow. In other organs, the radioactivity in the liver was high in the early period after the administration, but it decreased over time, and the radioactivity in the small intestine increased instead. This was judged to indicate that the labeled body was not accumulated in the body and was excreted in feces via the hepatobiliary system. What is more characteristic is that
The brain / blood ratio was 1.0 or more immediately after the administration, and in particular, the ligand-2,3-technetium-99m preparation solution showed a value of about 3 30 minutes after the administration. From this result,
It was suggested that when the brain is used as the target organ, the radioactivity of blood, which is the main background, is low, and images with good contrast can be obtained.

[0049]

[Table 1]

[0050]

[Table 2]

[0051]

[Table 3]

(Example 19) Production of a ready-to-use preparation kit. The compound (18 mg, 0.061 mmol) prepared in Example 6 was added to a 100 ml Erlenmeyer flask and dissolved in 0.5 ml of ethanol. 0.49 g (3.3 mmol) of L-(+)-tartaric acid, 1.1 g (4.8 mmol) of sodium tartrate dihydrate and HPCD4.0 were added thereto.
80 ml of an aqueous solution in which g was dissolved was added, and the mixture was stirred with a vortex mixer for 5 minutes. Then stannous chloride 9.4mg
(0.050 mmol) was added. The mixture was filtered through a membrane filter, and 2.0 ml of the mixture was dispensed into ampoules and sealed. The water used was degassed sterile water under an argon gas stream. All of the above operations were performed in a clean bench under an argon gas stream.

(Example 20) Preparation of technetium-99m complex using a fresh preparation kit. The kit of Example 19 enclosed in ampoules was withdrawn by using a syringe to transfer 0.5 ml to a 3.5 ml vial, and immediately thereafter, 0.5 ml of 20 mCi / ml sodium pertechnetate injection was added, and a steam autoclave was used. And heated at 120 ° C. for 20 minutes. Then, it returned to room temperature at room temperature. The purity of the technetium-99m complex was analyzed by using a C ₁₈ ODS thin layer plate with methanol / water = 9/1 as a developing solvent. At this time, the Rf value of the labeled complex was about 0.6, and the purity was 95% or more until 24 hours after the preparation.

(Example 21) Technetium-99m prepared by a ready-to-use preparation kit
Autoradiography with complex. Technetium-99m complex solution 2 prepared in Example 20
S was previously anesthetized with Labonar using 0 mCi / ml.
0.3 ml was administered from the tail vein of a female D rat (200 g). Blood was removed 5 minutes after the administration and the brain was removed. Blood around the brain was wiped off lightly and frozen with dry ice powder. After this, the cryostat (Jung, FRIGOCUT 2800
A frozen section of 10 μm was prepared in E), brought into contact with an X-ray film (Konica, New A), and exposed at −20 ° C. for 3 days. The film was developed by a usual method. It was determined that the obtained image at 5 minutes after administration was clear and reflected cerebral blood flow.

Example 22 Blood-Brain Barrier Permeability Comparison of Technetium-99m Complex Using a primary culture bovine brain capillary endothelial cell system known as an in vitro system capable of evaluating the blood-brain barrier permeability of substances, Example 20 was used. The blood-brain barrier permeability of the technetium-99m complex prepared in 1. was compared and evaluated with technetium-99m-hexamethylpropyleneamine oxime, which is generally used as a cerebral blood flow diagnostic agent. The results are shown in Table 4.

The rate of permeation from the blood to the brain of the labeled body prepared in Example 20 was as low as 1/3 of that of technetium-99m-hexamethylpropyleneamine oxime, which is less lipophilic than the labeled body. . Further, the intracellular accumulation amount for 20 minutes showed the same value in both cases. From the above results, the technetium-99m-complex prepared in Example 20 permeates the luminal membrane of the brain capillaries by simple diffusion, but the proportion of the technetium-99m-complex remains in the endothelial cells.
It was considered that the amount was higher than that of hexamethylpropyleneamine oxime.

Generally, if a compound penetrates the blood-brain barrier and moves into the intercellular fluid of the brain, it is necessary to take into consideration the intracerebral dynamics such as diffusion and metabolism in the brain, but the technetium prepared in Example 20 The -99m complex is useful as a diagnostic agent for imaging cerebral blood flow because it has a small amount of transfer into brain intercellular fluid and accumulates in endothelial cells as described above. it was thought.

[0058]

[Table 4]

Example 23 Safety of Technetium-99 Complex. According to the preparation method shown in Example 15, a radioactively attenuated ligand-1-technetium-99 complex was prepared. About 0.4 ml of this preparation was injected from the tail vein of SD female rats.
Although kg body weight (about 50 times the estimated clinical dose) was administered, there were no deaths and no particularly abnormal symptoms were observed.

[0060]

INDUSTRIAL APPLICABILITY According to the present invention, the stability of the complex after preparation is high, the complex is rapidly taken up by the brain after administration, is retained for an appropriate time, has a low blood level after in vivo administration, and has good clearance. It has become possible to provide a chelate-forming compound useful for imaging the brain of a mammal, including the compound, a complex comprising the compound and a radioactive metal, and a radioactive diagnostic agent containing the complex.

[Brief description of drawings]

FIG. 1 is a synthetic route diagram of the compound represented by Chemical formula 1.

FIG. 2 is a synthetic route diagram of a reaction product used for the synthesis of the compound represented by Chemical formula 1.

FIG. 3 is a synthetic pathway diagram of a reaction product used for the synthesis of the compound represented by Chemical formula 1.

FIG. 4 is a synthetic pathway diagram of a dimer of the compound represented by Chemical formula 4.

FIG. 5: Technetium-99m of the compound represented by Chemical formula 3
Autoradiogram of the hippocampus using a complex (morphology of living organisms).

FIG. 6 Technetium-99m of the compound represented by Chemical formula 3
Autoradiogram of the cerebellum using a complex (morphology of living organisms).

[Chemical 4]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Miki Kurami, No. 1 Kitasode, Sodegaura City, Chiba Prefecture, Japan 1.

Claims (13)

[Claims] 1. A chelate-forming compound having the following structure or a salt thereof. [Chemical 1] In Formula 1, R is hydrogen, an alkyl group having 1 to 8 carbon atoms, an aminoalkyl group having 1 to 8 carbon atoms, and 2 to 16 carbon atoms.
Is a C4 to C13 alkyl cyclic alkyl group, a C2 to C5 alkenyl group, or a C2 to C5 alkynyl group. 2. The chelate according to claim 1, wherein R is a methyl group.
Forming compound or salt thereof. 3. The chelate-forming compound according to claim 1, wherein R is an n-propyl group, or a salt thereof. 4. The chelate-forming compound according to claim 1, wherein R is an isopropyl group, or a salt thereof. 5. The chelate-forming compound according to claim 1, wherein R is a 2-propenyl group, or a salt thereof. 6. The chelate-forming compound according to claim 1, wherein R is a cyclopropylmethyl group, or a salt thereof. 7. The chelate-forming compound according to claim 1, wherein R is a pentyl group, or a salt thereof. 8. The chelate-forming compound according to claim 1, wherein R is a methoxyethyl group, or a salt thereof. 9. The chelate-forming compound according to claim 1, wherein R is a 2-aminoethyl group, or a salt thereof. 10. The chelate-forming compound according to claim 1, wherein R is a 2-propynyl group, or a salt thereof. 11. Claims 1, 2, 3, 4, 5, 6, 7,
A complex comprising the chelate-forming compound according to 8, 9 or 10 or a salt thereof and a radioactive metal. 12. A radioactive diagnostic agent comprising the complex according to claim 11. 13. The radioactive diagnostic agent according to claim 12, wherein the radioactive metal is technetium-99m.