WO2021172515A1 - Diagnostic imaging agent for oligomeric amyloid - Google Patents

Abstract

Disclosed are a diagnostic imaging agent used for detecting oligomeric amyloid-β, with the active ingredient of the diagnostic imaging agent being a curcumin derivative that is present only in a keto form structure or a salt thereof; and a curcumin derivative represented by formula (IA): (in the formula, each R¹ is independently a hydrogen atom, a fluorine atom, CH₃-, CH₂F-, CHF₂-, CF₃-, CH₃O-, CH₂FO-, CHF₂O-, or CF₃O-; each R² is independently a hydrogen atom or a fluorine atom; A is alkyl, cyano, carboxy, alkoxycarbonyl, or R³-(CH₂)_m-; R³ is hydroxy, carboxy, cyano, alkylcarbonyloxy, alkoxycarbonyl, alkoxyalkoxy, hydroxyalkoxy, or CONR⁴R⁵; R⁴ and R⁵ are each independently a hydrogen atom or alkyl; and m is an integer of 1-5 (provided that when R¹s are both CH₃O- or CF₃O-, and R²s are both a hydrogen atom, A must not be CH₃-)) or a salt thereof.

Description

Amyloid Oligomer Diagnostic Diagnostic Agent

The present invention relates to a diagnostic imaging agent used for detecting an amyloid β oligomer, and a curcumin derivative or a salt thereof.

The number of dementia patients in Japan exceeds 5 million, and it is estimated that it will reach 7 million by 2025, and the solution is an urgent and important problem. Alzheimer's disease (AD) is the most common type of dementia, and the clinical symptoms of Alzheimer's disease include memory impairment and higher brain dysfunction (aphasia, apraxia, agnosia, constructional apraxia). The symptoms are often seen in other dementia diseases, and it is extremely difficult to make a definitive diagnosis of Alzheimer's disease based on clinical symptoms alone.

Also, in AD, the development of radical therapeutic agents has all failed. Brain pathology of Alzheimer's disease has progressed 20 to 30 years before the onset, and the importance of preemptive medical treatment that diagnoses and treats before the onset has been pointed out.

Characteristic histopathological findings of Alzheimer's disease include amyloid plaque and neurofibrillary tangles. The main constituent of the former is amyloid β protein with a β-sheet structure, and that of the latter is hyperphosphorylated tau protein. It is known that in Alzheimer's disease, the above-mentioned pathological tissue changes such as accumulation of aggregated amyloid β protein have started long before the onset of clinical symptoms. Therefore, detection of aggregated amyloid β protein as a marker is one of the early diagnostic methods for diseases in which amyloid accumulates, particularly Alzheimer's disease.

Amyloid β peptide (Aβ) oligomers play an important role in the early stages before the onset of AD. Aβ aggregates become Aβ fibers (Aβ fibrils) via Aβ oligomers. Since treatment after the onset of AD is difficult, it is important to establish an accurate diagnostic method and develop a treatment method in the 40s and 50s when toxic oligomers begin to accumulate.

From this point of view, in recent years, research on radiocontrast agents for positron emission tomography (PET) and single photon tomography (SPECT) that selectively bind to amyloid β protein in the brain has been promoted. Classic compounds with high amyloid affinity include Congo Red, Thioflavin S and Thioflavin T, which are used in the pathologically definitive diagnosis of Alzheimer's disease. Most of them do not easily cross the blood-brain barrier and are hardly transferred into the brain even when administered intravenously.

In addition, there is a nuclear magnetic resonance imaging (MRI) as one of the diagnostic methods that does not use radionuclides. So far, the present inventors have reported that they have succeeded in imaging amyloid plaque by fluoromagnetic resonance imaging (fluorine MR imaging) using a curcumin derivative (Patent Documents 1 and 2). In addition, Patent Document 3 reports a curcumin derivative that interacts with Aβ fibers and can be used to detect Aβ fibers.

However, so far no reports have been made on small molecule compounds that specifically bind to Aβ oligomers.

International Publication No. 2010/098502 International Publication No. 2014/109296 Japanese Patent Application Laid-Open No. 2018-138528

An object of the present invention is to provide a diagnostic imaging agent used for detecting amyloid β oligomer and a substance that specifically binds to amyloid β oligomer.

The present inventors have clarified that curcumin and curcumin derivatives bind not only to Aβ fibers but also to Aβ oligomers.

As a result of intensive studies to achieve the above object, the present inventors have analyzed the chemical mechanism of curcumin derivatives as described in Patent Documents 1 and 2, and have keto-enol tangles of curcumin. Considering that sex plays an important role, we synthesized a curcumin derivative that has only a keto-type structure. As a result, it was found that a curcumin derivative having only such a keto-type structure specifically binds to an Aβ oligomer.

The present invention has been completed by further studying based on these findings, and provides a diagnostic imaging agent, a curcumin derivative, a salt thereof, etc. used for detecting the next amyloid β oligomer.

Item 1. An diagnostic imaging agent used for detecting an amyloid β oligomer containing a curcumin derivative having only a keto-type structure or a salt thereof as an active ingredient.
Item 2. The curcumin derivative is of formula (I):

(In the formula, R ¹ is independently hydrogen atom, fluorine atom, CH _3- , CH ₂ F-, CHF _2- , CF _3- , CH ₃ O-, CH ₂ FO-, CHF ₂ O- or CF ₃ O-, R ² is an independent hydrogen or fluorine atom, A is alkyl, cyano, carboxy, alkoxycarbonyl or R ^3- (CH ₂ ) _m- , and R ³ is hydroxy, carboxy, cyano. , Alkylcarbonyloxy, alkoxycarbonyl, alkoxyalkoxy, hydroxyalkoxy or CONR ⁴ R ⁵ , where R ⁴ and R ⁵ are independently hydrogen atoms or alkyl, m is an integer from 1 to 5) Item 2. The diagnostic imaging agent according to Item 1, which is a curcumin derivative.
Item 3. Item 2. The diagnostic imaging agent according to Item 2, wherein R ¹ is a fluorine atom, CH ₂ F- _{, CH F 2-} , CF _3- , CH ₂ FO-, _{CH F 2} O- or CF _{3 O-, respectively.}
Item 4. Item 4. The diagnostic imaging agent according to any one of Items 1 to 3, which is used for diagnosing a disease in which amyloid β protein is accumulated.
Item 5. Item 4. The diagnostic imaging agent according to Item 4, wherein the disease in which amyloid β protein is accumulated is Alzheimer's disease.
Item 6. Item 4. The diagnostic imaging agent according to any one of Items 1 to 5, wherein the diagnostic imaging is MRI.
Item 7. A method for detecting an amyloid β oligomer using the diagnostic imaging agent according to any one of Items 1 to 3.
Item 8. A method for diagnosing a disease in which amyloid β protein accumulates, using the diagnostic imaging agent according to any one of Items 1 to 3.
Item 9. Formula (IA):

(In the formula, R ¹ is independently hydrogen atom, fluorine atom, CH _3- , CH ₂ F-, CHF _2- , CF _3- , CH ₃ O-, CH ₂ FO-, CHF ₂ O- or CF ₃ O-, R ² is independently a hydrogen atom or a fluorine atom, A is alkyl, cyano, carboxy, alkoxycarbonyl or R ^3- (CH ₂ ) _m- , and R ³ is hydroxy, carboxy, cyano. , Alkylcarbonyloxy, alkoxycarbonyl, alkoxyalkoxy, hydroxyalkoxy or CONR ⁴ R ⁵ , where R ⁴ and R ⁵ are each independently a hydrogen atom or alkyl, where m is an integer from 1 to 5 (where R). ^{If 1} is both CH ₃ O- or CF ₃ O- and R ² are both hydrogen atoms, then A _{must not be CH 3-} ))) a curcumin derivative or salt thereof.
Item 10. Item 2. The curcumin derivative or salt thereof according to Item 9, wherein R ¹ is a fluorine atom, CH ₂ F- _{, CH F 2-} , CF _3- , CH ₂ FO-, _{CH F 2} O- or CF _{3 O-, respectively.} ..

The diagnostic imaging agent of the present invention contains a compound having high binding specificity for Aβ oligomer as an active ingredient, and can be used for detecting Aβ oligomer. In addition, the curcumin derivative of the present invention or a salt thereof has high binding specificity for Aβ oligomers, and is useful as an active ingredient of a diagnostic imaging agent used for detecting Aβ oligomers.

According to the present invention, since the Aβ oligomer plays an important role in the early stage before the onset of AD, it is possible to make an early diagnosis of a disease in which amyloid β protein is accumulated in the early stage before the onset of AD.

It is a graph which shows the analysis result of the binding property with Aβ oligomer and Aβ fiber using the quartz crystal microbalance (QCM) measuring apparatus carried out in Test Example 1. The upper row shows the frequency change for Aβ fibers, and the lower row shows the frequency change for Aβ oligomers. * p <0.05 vs vehicle (20 minutes later, Mann Whitney test), Aβ oligomer and Aβ fiber n = 5, vehicle n = 3 It is a graph which shows the analysis result of the binding property with Aβ oligomer and Aβ fiber using the QCM apparatus carried out in Test Example 1. The upper row shows the total amount of Aβ fibers or compounds bound to the solvent, and the lower row shows the total amount of Aβ oligomers or compounds bound to the solvent (pmol / 1 nmol Aβ). * p <0.05 vs vehicle (Mann Whitney test), Aβ oligomer and Aβ fiber n = 5, vehicle n = 3 It is a graph which shows the time-dependent change of the peak area of the ¹⁹ F-NMR signal by MRI measured by administering compound 1 to APP / PS1 mouse and wild-type mouse from the tail vein in Test Example 2. The solid line shows the results using 16-month-old APP / PS1 mice, and the dashed line shows the results using 12-month-old wild-type mice. n = 3 6 is an MRI brain image measured by administering Compound 1 to APP / PS1 mice and wild-type mice from the tail vein in Test Example 2. The left is the result of using a 16-month-old APP / PS1 mouse, and the right is the result of using a 12-month-old wild-type mouse.

Hereinafter, embodiments of the present invention will be described in detail.

The diagnostic imaging agent used for detecting the amyloid β oligomer of the present invention is characterized by containing a curcumin derivative having only a keto-type structure or a salt thereof as an active ingredient.

In the present invention, the amyloid β protein is a protein consisting of 38 to 43 amino acids, and means a protein produced by the action of a protease from the amyloid precursor protein, and the Aβ oligomer has 2 to several tens of Aβ (particularly 2). ~ 30) It is a collection.

The curcumin derivative used in the present invention is a compound having only a keto-type structure, and the keto-type indicates that both are ketones in the central portion of the curcumin derivative shown below, and one of the enol-type is one of them. Indicates an enolized substance.

The curcumin derivative of the present invention or a salt thereof has a property of high binding specificity to Aβ oligomer, which plays an important role in the early stage before the onset of AD.

The curcumin derivative of the present invention or a salt thereof is not particularly limited as long as it is a compound having a curcumin structure and having only a keto-type structure. When the curcumin derivative of the present invention or a salt thereof contains an asymmetric carbon, both the optical isomer and the racemate separated according to a conventional method are included in the compound of the present invention.

The curcumin derivative of the present invention may be a salt, and the salt may be any pharmaceutically acceptable salt, for example, an alkali metal salt such as a potassium salt or a sodium salt; an alkali metal salt such as a calcium salt. Alkaline earth metal salts; examples include triethanolamine salts, organic amine salts such as tris (hydroxymethyl) aminomethane salts, and the like. In addition, some of these salts have water of crystallization.

Preferred curcumin derivatives of the present invention include curcumin derivatives represented by the following formula (I) or salts thereof.
Equation (I):

(In the formula, R ¹ is independently hydrogen atom, fluorine atom, CH _3- , CH ₂ F-, CHF _2- , CF _3- , CH ₃ O-, CH ₂ FO-, CHF ₂ O- or CF ₃ O-, R ² is independently a hydrogen atom or a fluorine atom, A is alkyl, cyano, carboxy, alkoxycarbonyl or R ^3- (CH ₂ ) _m- , and R ³ is hydroxy, carboxy, cyano. , Alkylcarbonyloxy, alkoxycarbonyl, alkoxyalkoxy, hydroxyalkoxy or CONR ⁴ R ⁵ , where R ⁴ and R ⁵ are independently hydrogen atoms or alkyl, and m is an integer of 1-5.)

The curcumin derivative represented by the following formula (IA) or a salt thereof is a novel compound not described in the literature contained in the curcumin derivative represented by the formula (I) or a salt thereof.
Formula (IA):

(In the formula, R ¹ is independently hydrogen atom, fluorine atom, CH _3- , CH ₂ F-, CHF _2- , CF _3- , CH ₃ O-, CH ₂ FO-, CHF ₂ O- or CF ₃ O-, R ² is independently a hydrogen atom or a fluorine atom, A is alkyl, cyano, carboxy, alkoxycarbonyl or R ^3- (CH ₂ ) _m- , and R ³ is hydroxy, carboxy, cyano. , Alkylcarbonyloxy, alkoxycarbonyl, alkoxyalkoxy, hydroxyalkoxy or CONR ⁴ R ⁵ , each of R ⁴ and R ⁵ is a hydrogen atom or alkyl independently, m is an integer of 1-5, preferably 1-3. (However, if R ¹ is both CH ₃ O- or CF ₃ O- and R ² are both hydrogen atoms, then A must not be _{CH 3-))}

R ¹ is preferably a fluorine atom, CH ₂ F-, CHF _2- , CF _3- , CH ₂ FO-, CHF ₂ O- or CF ₃ O-, respectively.

The alkyl of A, R ⁴ and R ⁵ may be a straight chain or branched C _1-6 alkyl, and a straight chain or branched C _1-3 alkyl is preferable. The alkyl specification also applies to alkylcarbonyloxy, alkoxycarbonyl, alkoxyalkoxy and hydroxyalkoxy alkyls in compounds of formula (I).

Specific examples of C _1-6 alkyl include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, and hexyl.

Specific examples of C _1-3 alkyl include methyl, ethyl, n-propyl, and isopropyl.

The curcumin derivative of formula (I) or formula (IA) or a salt thereof can be produced by the method described below.

The compound of formula (I) can be produced by hydrolyzing the compound of formula (II).

(In the formula, R ¹ , R ² and A are as described above.)

Solvents for this reaction include alcohols such as methanol, ethanol, n-propanol, iso-propanol and butanol; ethers such as hydrous tetrahydrofuran and hydrodioxane; acid amides such as hydrous dimethylformamide and hydrous dimethylacetamide; hydrous dimethyl. Examples thereof include sulfoxides such as sulfoxide and mixed solvents thereof.

It is desirable to add a mineral acid to promote this reaction, and examples of the mineral acid include hydrochloric acid, sulfuric acid, nitric acid, and perchloric acid. The mineral acid can be used in 3 to 10 times mol, preferably 4 to 6 times mol, with respect to the compound of formula (II).

This reaction can be carried out at 0 to 150 ° C, preferably 30 to 100 ° C, and the reaction time is usually about 1 to 150 hours.

The compound (II) can be produced by reacting the compound of the formula (III) with methyl iodide.

(In the formula, R ¹ , R ² and A are as described above.)

Solvents for this reaction include aromatic hydrocarbons such as benzene, toluene and xylene; aliphatic hydrocarbons such as pentane, hexane, petroleum ether and ligroin; diethyl ether, dipropyl ether, dibutyl ether, tetrahydrofuran, dioxane and the like. Ethers; Ketones such as acetone and 2-butanone; nitriles such as acetonitrile and propionitrile; Acid amides such as dimethylformamide and dimethylacetamide; can.

It is desirable to add a base to promote this reaction, and the bases are triethylamine, pyridine, N-methylmorpholin, 1,8-diazabicyclo [5,4,0] -7-undecene, N, N. -Organic bases such as dimethylaniline; alkali metal carbonates such as sodium carbonate and potassium carbonate; alkali metal hydrogen carbonates such as sodium hydrogen carbonate and potassium hydrogen carbonate; alkali metal water such as sodium hydroxide and potassium hydroxide Oxides: Hydroxides of alkaline earth metals such as barium hydroxide and calcium hydroxide can be mentioned. The base can be used in 3 to 20 times mol, preferably 5 to 10 times mol, with respect to the compound of formula (III).

This reaction can usually be carried out at 0 to 70 ° C, and the reaction time is about 1 to 48 hours.

In addition, it is desirable to use 2 to 20 times the molar amount of methyl iodide with respect to the compound of formula (III).

The compound of formula (III) can be produced by condensing the compound of formula (IV) and the compound of formula (V). However, the compound of formula (IV) needs to undergo a 2-fold molar reaction with the compound of formula (V). The compound of formula (V) can be produced by a known method.

(In the formula, R ¹ , R ² and A are as described above.)

In order to proceed the reaction efficiently, it is desirable to carry out the reaction in the presence of a boron compound and a base in a solvent. Examples of the boron compound that can be used in this reaction include boric acid, diboron trioxide, trimethyl borate, triethyl borate, tripropyl borate, tri-n-butyl borate, and tri-tert-butyl borate. Alternatively, a mixture of diboron trioxide and various boric acid esters can be mentioned. It is desirable to use the boric acid compound in an amount of 0.5 to 6 times the molar amount of the compound of the formula (IV).

Primary amines such as n-butylamine, sec-butylamine, tert-butylamine, n-propylamine, n-hexylamine, cyclohexylamine; morpholine, piperidine, 1,2,3,4-tetrahydro Secondary amines such as quinoline can be mentioned. It is desirable to use 1 times the molar amount of the base with respect to the compound of the formula (V).

As the solvent, aromatic hydrocarbons such as benzene, toluene and xylene; aliphatic hydrocarbons such as pentane, hexane, heptane, petroleum ether and ligroine; diethyl ether, dipropyl ether, dibutyl ether, tetrahydrofuran and dioxane. Ethers such as; ester such as methyl acetate, ethyl acetate, methyl propionate; acid amides such as dimethylformamide and dimethylacetamide; sulfoxides such as dimethylsulfoxide; phosphate amides such as hexamethylphosphortriamide and these. Can be mentioned.

The reaction temperature can usually be 0 to 150 ° C, preferably 0 to 100 ° C, and the reaction time is usually about 0.5 to 24 hours.

Further, in the above reaction, after the reaction, it is necessary to treat the reaction solution with an acid in order to decompose the boron complex of the compound of the formula (III) produced. Examples of the acid used at that time include mineral acids such as hydrochloric acid and sulfuric acid, and organic acids such as acetic acid and propionic acid.

The compound of formula (IV) can be produced by reacting the compound of formula (VI) with chlorodimethyl ether. The compound of formula (VI) can be produced by a known method.

(In the formula, R ¹ and R ² are as described above.)

Solvents include aromatic hydrocarbons such as benzene, toluene and xylene; aliphatic hydrocarbons such as pentane, hexane, heptane, petroleum ether and ligroin; diethyl ether, dipropyl ether, dibutyl ether, tetrahydrofuran, dioxane and the like. Ethers; Ketones such as acetone and 2-butanone; nitriles such as acetonitrile and propionitrile; Acid amides such as dimethylformamide and dimethylacetamide; Sulfoxides such as dimethylsulfoxide; dichloromethane, carbon tetrachloride, 1,2 -Halogenized hydrocarbons such as dichloroethane and mixed solvents thereof can be mentioned.

It is desirable to add a base to promote this reaction, and the bases are triethylamine, pyridine, N-methylmorpholin, N-methylpiperidin, 1,8-diazabicyclo [5,4,0] -7. -Organic bases such as undecene, N, N-dimethylaniline; alkali metal carbonates such as sodium carbonate and potassium carbonate; alkali metal bicarbonates such as sodium hydrogen carbonate and potassium hydrogen carbonate; sodium hydroxide and potassium hydroxide Alkali metal hydroxides and the like can be mentioned. The base can be used in 1-3-fold mol, preferably 1.4-1.8-fold mol, with respect to the compound of formula (VI).

This reaction can usually be carried out at 0 to 50 ° C, and the reaction time is usually about 1 to 48 hours.

The compound of the formula (I) obtained by the above-mentioned production method and the method incidental thereto can be obtained by known means, for example, concentration, concentration under reduced pressure, distillation, fractional distillation, dissolution, solvent extraction, crystallization, recrystallization, chromatography. It can be isolated and purified by such means.

When the compound of the formula (I) is obtained in a free form, a salt can be formed by a usual method.

Specific examples of the compound of the formula (I) are shown in Table 1 below.

Most of the curcumin derivatives of formula (I) are hydrophobic compounds and have low solubility in water. As a compound to be administered to a living body, it is desirable that the compound has high water solubility, and among the compounds of the formula (I), a compound having a salt is more desirable.

A curcumin derivative having only a keto-type structure or a salt thereof can be used as a diagnostic imaging agent used for detecting an Aβ oligomer. MRI is desirable for diagnostic imaging.

When a curcumin derivative having only a keto-type structure or a salt thereof is used as a diagnostic imaging agent, the Aβ oligomer in the brain can be specifically detected by the compound. In particular, ^{when Aβ oligomers are detected non-invasively using 19} F-MRI, the detection sensitivity depends on the number of fluorine atoms, so more fluorine atoms are included in the compounds of formula (I). Compounds containing are more desirable.

A curcumin derivative or a salt thereof, which has only a keto-type structure, specifically binds to an Aβ oligomer that plays an important role in the early stage before the onset of AD, so that the site of the Aβ oligomer can be detected. Become. Therefore, a curcumin derivative having only a keto-type structure or a salt thereof can be used as an image diagnostic agent for a disease in which amyloid β protein is accumulated, and an early diagnosis of a disease in which amyloid β is accumulated at a presymptomatic stage. Is possible.

When a curcumin derivative having only a keto-type structure or a salt thereof is used as a diagnostic imaging agent, its administration may be local or systemic. The administration method is not particularly limited and is administered orally or parenterally. Parenteral routes of administration include subcutaneous, intraperitoneal, intravenous, arterial or spinal fluid injections, infusions and the like.

A diagnostic imaging agent containing a curcumin derivative having only a keto-type structure or a salt thereof is a pharmaceutically acceptable form suitable for administration to humans and contains a physiologically acceptable additive. Such compositions may optionally be pharmaceutically acceptable diluents, buffers, solubilizers (eg, cyclodextrin, polyethylene glycol, Pluronic ™, Tween ™, Cremofol ™ or phospholipids). Surfactants), soothing agents, etc. may be added, and if necessary, components such as pharmaceutically acceptable solvents, stabilizers, or antioxidants (eg, ascorbic acid, etc.) may be added. good. The dose of the curcumin derivative having only the keto-type structure or a salt thereof is appropriately selected depending on the usage, the age of the patient, the sex and other conditions, and the degree of the disease.

Diseases in which amyloid β protein accumulates include Down's syndrome in addition to Alzheimer's disease.

Next, synthetic examples and test examples related to the present invention will be described, but the present invention is not limited thereto.

[Synthesis Example 1] Synthesis of 1,7-bis (4'-hydroxy-3'-trifluoromethoxy) phenyl-4-ethyl-4-methyl-1,6-heptadiene-3,5-dione (Compound 1) (1) A mixture of 4-hydroxy-3- (trifluoromethoxy) benzaldehyde (2.06 g; 10 mmol) in acetone (18 mL) and potassium carbonate (2.21 g; 16 mmol) was ice-cooled and here. Chloromethylmethyl ether (1.07 mL; 14 mmol) was added in small portions with stirring. The reaction mixture was stirred at room temperature for 10 hours, the solvent was distilled off under reduced pressure, and the obtained residue was extracted with ethyl acetate. The extract was washed with water, then with saturated aqueous sodium hydrogen carbonate solution and saturated brine, and dried over magnesium sulfate. When the residue obtained by distilling off the solvent under reduced pressure was purified by silica gel column chromatography (eluent: ethyl acetate: n-hexane = 1: 3), 4-methoxymethoxy-3- (trifluoromethoxy) benzaldehyde 2.48 g (99%) was obtained as a colorless oil.

(2) Diboron triboron (140 mg; 2.0 mmol) was added to a solution of 3-ethyl-2,4-pentandione (256 mg; 2.0 mmol) in ethyl acetate (4.0 mL), and the mixture was heated at 70 ° C. for 30 minutes. Then, tributyl borate (1.08 mL; 4.0 mmol) and 4-methoxymethoxy-3- (trifluoromethoxy) benzaldehyde (1.00 g; 4.0 mmol) obtained in the above step (1) were added, and 30 at the same temperature. Heated for minutes. Further, butylamine (0.20 mL; 2.0 mmol) was added, and the mixture was heated at the same temperature for 5 hours. 2M-Hydrochloric acid (10 mL) was added to the reaction solution cooled to room temperature, and the mixture was vigorously stirred at room temperature for 30 minutes and then extracted with ethyl acetate. The extract was washed with water, then with saturated brine, and dried over magnesium sulfate. The residue obtained by distilling off the solvent under reduced pressure was purified by silica gel column chromatography (eluent: ethyl acetate: n-hexane = 1: 3) and found to be 1,7-bis (4'-methoxymethoxy-3'. '-Trifluoromethoxy) phenyl-4-ethyl-1,6-heptadiene-3,5-dione (282 mg; 24%) was obtained. Mp124-125 ℃
¹⁹ FNMR (CDCl ₃ ): δ -59.50 (s), ¹ HNMR (CDCl ₃ ): δ1.20 (3H, t, J = 7.2Hz), δ2.58 (2H, q, J = 7.2Hz), δ3 .50 (6H, s), δ5.26 (4H, s), δ6.96 (2H, d, J = 15.6Hz), δ7.2-7.3 (2H), δ7.4-7.5 (4H), δ7 .67 (2H, d, J = 15.6Hz), δ17.38 (1H, s)

(3) 1,7-Bis (4'-methoxymethoxy-3'-trifluoromethoxy) phenyl-4-ethyl-1,6-heptadiene-3,5-dione (237) obtained in the above step (2). Powdered potassium carbonate (550 mg; 4.0 mmol) was added to an acetone (10 mL) solution of mg; 0.40 mmol) and methyl iodide (0.25 mL; 4.0 mmol), and the mixture was heated at 55 ° C. for 3 hours. The solvent was distilled off under reduced pressure, and the obtained residue was extracted with ethyl acetate. The extract was washed with water, then with saturated brine, and dried over magnesium sulfate. When the residue obtained by distilling off the solvent under reduced pressure is purified by silica gel column chromatography (eluent: ethyl acetate: n-hexane = 1: 3), it is 1,7-bis (4'-methoxymethoxy-3'). -Trifluoromethoxy) phenyl-4-ethyl-4-methyl-1,6-heptadiene-3,5-dione 230 mg (95.0%) was obtained as a pale yellow oil.
¹⁹ FNMR (CDCl ₃ ): δ -59.59 (s), ¹ HNMR (CDCl ₃ ): δ0.82 (3H, t, J = 7.2Hz), δ1.42 (3H, s), δ2.05 (2H, s) q, J = 7.2Hz), δ3.46 (6H, s), δ5.23 (4H, s), δ6.65 (2H, d, J = 15.6Hz), δ7.17 (2H, d, J = 8.4Hz), δ7.38 (2H, br.s), δ7.40 (2H, dd, J = 2Hz, 8.4Hz), δ7.62 (2H, d, J = 15.6Hz)

(4) 1,7-Bis (4'-methoxymethoxy-3'-trifluoromethoxy) phenyl-4-ethyl-4-methyl-1,6-heptadiene-3,5 obtained in the above step (3). 1M-Methoxy (1.80 mL; 1.80 mmol) was added to a solution of -dione (182 mg; 0.30 mmol) in ethanol (6.0 mL), and the mixture was heated to 60-65 ° C. for 4 hours. The solvent was distilled off under reduced pressure and the obtained residue was extracted with ethyl acetate. The extract was washed with water, washed with saturated brine, and dried over magnesium sulfate. When the solvent was distilled off under reduced pressure and the obtained residue was purified by silica gel column chromatography (eluent: ethyl acetate: n-hexane = 1: 3), 1,7-bis (4'-hydroxy-) of colorless crystals was purified. 3'-Trifluoromethoxy) phenyl-4-ethyl-4-methyl-1,6-heptadiene-3,5-dione 101 mg (65%) was obtained. Mp89-91 ℃ ¹⁹ FNMR (CDCl ₃ ): δ -59.22 (s), ¹ HNMR (CDCl ₃ ): δ0.82 (3H, t, J = 7.2Hz), δ1.42 (3H, s), δ2. 05 (2H, q, J = 7.2Hz), δ5.69 (2H, s), δ6.64 (2H, d, J = 15.6Hz), δ7.01 (2H, d, J = 8.4Hz), δ7 .35 (2H, br.s), δ7.39 (2H, dd, J = 2Hz, 8.4Hz), δ7.61 (2H, d, J = 15.6Hz)

Compound 3 used in the following test examples was synthesized according to the description in Synthesis Example 1 of Japanese Patent Application Laid-Open No. 2014-105196. Compound 3 has the following structure. Compound 3 is a compound having keto-enol tautomerism.

[Test Example 1] Analysis of binding to Aβ oligomers and Aβ fibers using a quartz crystal microbalance (QCM) device The quartz crystal microbalance (QCM) measuring device used in this test is AffinitxQ (Initium, Inc., Inc.). Tokyo) was used. This device is a 27-MHz QCM analyzer that can detect the binding of trace substances with high sensitivity by utilizing the fact that the vibration frequency decreases when the compound fixed to the crystal oscillator sensor and the test substance combine. In this test, Aβ fibers having a β-sheet structure or Aβ aggregates such as Aβ oligomers were fixed to the sensor part of the QCM device and reacted with each reagent. Aβ fibrils and Aβ oligomers (oligomer, Globulomer-type) were prepared as follows.

To prepare Aβ aggregates, use Aβ _1-42 peptide (Peptide Institute, Ltd.) with 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) (Fujifilm Wako Pure Chemical Industries, Ltd.) ) Was dissolved at a concentration of 1 mM, cooled at 37 ° C for 1 hour, HFIP was removed by suction, and the mixture was stored at -30 ° C. Before use, it was dissolved in dimethyl sulfoxide (DMSO, dehydrated) to a concentration of 5 mM before use. For Aβ fibers, _{dilute a 5 mM Aβ 1-42} DMSO solution with dalbecolinic acid buffered saline (D-PBS, Ca, Mg-free, Nacalai Tesque, Inc.) to prepare a 100 μM solution, and prepare a 100 μM solution at 37 ° C. for 48 hours. Made by incubation. For Aβ oligomer, _{dilute a 5 mM Aβ 1-42} DMSO solution with a D-PBS solution containing 0.2% sodium dodecyl sulfate (SDS) to 400 μM, leave it at 37 ° C for 6 hours, and then add pure water to make a final concentration of 100 μM solution. , Further incubated at 37 ° C. for 18 hours. After centrifuging 14,000 g of this solution for 10 minutes, the supernatant was used.

Next, in a binding test using a QCM device, 2 μL of Aβ oligomer, Aβ fiber or solvent was dried and fixed on the sensor part (Aβ oligomer was left overnight at 4 ° C. in a wet state, and further dried at 4 ° C. for 24 hours. ). After immersing the sensor in PBS in a glass cell container to stabilize it, add compounds 1 and 3 to a final concentration of 10 μM and thioflavin T (Anaspec) to a final concentration of 30 μM, and immediately after that, change the frequency. Recorded.

The obtained results are shown in FIGS. 1, 2 and 2. The upper part of FIG. 1 shows the frequency change for Aβ fibers, and the lower part shows the frequency change for Aβ oligomers. When compound 3 was added, both the sensor with fixed Aβ fibers (fibril) and the sensor with fixed Aβ oligomer (oligomer) showed a significant decrease in frequency compared with the sensor (vehicle) in the control experiment in which only the solvent was fixed. (Fiber n = 5, oligomer n = 5, vehicle n = 3). On the other hand, when compound 1 was added, a decrease in frequency was observed in the sensor on which the Aβ oligomer was fixed, but there was almost no difference from the control in the sensor on which the Aβ fiber was fixed. Thioflavin T, which is known to specifically bind to Aβ fibers, showed a decrease in frequency in the sensor with fixed Aβ fibers, but in the sensor with fixed Aβ oligomers, the control did not fix Aβ. No difference was found.

The upper part of FIG. 2 shows the total amount of compounds bound to Aβ fibers 20 minutes after the addition of the compound, and the lower part shows the total amount of compounds bound to Aβ oligomers. Compound 3 was both Aβ fiber and Aβ oligomer, compound 1 was only Aβ oligomer, and thioflavin T was only Aβ fiber, and significantly higher binding amounts were obtained.

Furthermore, Table 2 shows the molar ratio of the amount of Aβ oligomer bound to Aβ fibers. This value increases when it is more likely to bind to Aβ oligomers than Aβ fibers. It can also be seen from Table 2 that Compound 1 has a higher binding selectivity for Aβ oligomers than Compound 3 and Thioflavin T.

From the above results, it was shown that compound 3 has the property of binding to both Aβ oligomers and Aβ fibers, but compound 1 binds to Aβ oligomers but has low binding to Aβ fibers.

[Test Example 2] ¹⁹ F-MR imaging test of compound 1 10 mg of compound 1 was weighed, 0.125 ml of 80% Cremophor-EL was added, and the mixture was dissolved while warming. Then, 0.875 ml of physiological saline was added to prepare an administration solution (10 mg / ml). This administration solution was applied to wild-type mice (12 months old, 1 male, 2 females) or APP / PS1 mice (16 months old, 2 males, 1 female) anesthetized with sodium pentobarbital, and tail veins. A total of 200 mg / kg was administered at 0.5 ml / kg / min.

^{Then, the 19} F-MR signal of the mouse head was measured using an MR device. The measurement is performed by first performing a single pulse measurement for acquiring the NMR spectrum for 10 minutes, then repeating the measurement for 50 minutes for imaging by the Chemical Shift Imaging method (CSI method), and adding the data after the measurement is completed to obtain the image. It was created.

The obtained results are shown in FIGS. 3 and 4. FIG. 3 shows the time course of the peak area ^{of the 19} F-NMR signal in wild-type mice (broken line) and APP / PS1 mice (solid line) to which Compound 1 was administered. The peak area of APP / PS1 mice was larger than that of wild-type mice at all time points, indicating that compound 1 was accumulated in the brain of APP / PS1 mice.

In FIG. 4, the left is a ¹⁹ F-MR image of an ^{APP / PS1 mouse, and the right is a 19} F-MR image of a wild-type mouse. ^{19 In the} F-MR image, a signal (arrow) presumed to be Aβ oligomer was detected in the brain.

[Test Example 3] Analysis of brain transferability of compound 1 10 mg of compound 1 was weighed, 0.125 ml of 80% Cremophor-EL was added, and the mixture was dissolved while warming. Then, 0.875 ml of physiological saline was added to prepare an administration solution (10 mg / ml). This administration solution (dose of 200 mg / kg) and the administration solution containing only the solvent (vehicle) were administered to wild-type mice (6.5 months old, 1 female each) from the tail vein. After 30 minutes of administration, the mice were euthanized by overdose of sodium pentobarbital, and then the brain was removed and _{homogenized with 4 times the amount of CD 3} OD to prepare a methanol solution of the extract.

Next, analysis was performed using a liquid chromatograph mass spectrometer (LC / MS). The LC device used an Agilent 1290 binary pump. Analytical conditions are analytical column ZORBAX Eclipse Plus C18 1.8 μm 2.1 × 50 mm, A: 4 mM HCOONH ₄ (pH 6.4) B: CAN, 0 min A90%, 1 min A90%, 6 min A20%, 7 min A20% Met. The MS device used QTRAP 5500 negative ion mode.

Table 3 below shows the concentration of Compound 1 in the mouse brain sample solution determined from the ionic strength observed by LS / MS.

Claims (9)

1. A diagnostic imaging agent used to detect amyloid β oligomers containing a curcumin derivative or a salt thereof, which has only a keto-type structure, as an active ingredient.
2. The curcumin derivative is of formula (I):
   

   

   (In the formula, R ¹ is independently hydrogen atom, fluorine atom, CH _3- , CH ₂ F-, CHF _2- , CF _3- , CH ₃ O-, CH ₂ FO-, CHF ₂ O- or CF ₃ O-, R ² is an independent hydrogen or fluorine atom, A is alkyl, cyano, carboxy, alkoxycarbonyl or R ^3- (CH ₂ ) _m- , and R ³ is hydroxy, carboxy, cyano. , Alkylcarbonyloxy, alkoxycarbonyl, alkoxyalkoxy, hydroxyalkoxy or CONR ⁴ R ⁵ , where R ⁴ and R ⁵ are independently hydrogen atoms or alkyl, m is an integer from 1 to 5) The diagnostic imaging agent according to claim 1, which is a curcumin derivative.
3. The diagnostic imaging agent according to claim 2, wherein R ¹ is a fluorine atom, CH ₂ F- _{, CH F 2-} , CF _3- , CH ₂ FO-, _{CH F 2} O- or CF _{3 O-, respectively.}
4. The diagnostic imaging agent according to any one of claims 1 to 3, which is used for diagnosing a disease in which amyloid β protein is accumulated.
5. The diagnostic imaging agent according to claim 4, wherein the disease in which amyloid β protein is accumulated is Alzheimer's disease.
6. The diagnostic imaging agent according to any one of claims 1 to 5, wherein the diagnostic imaging is MRI.
7. A method for detecting amyloid β oligomer using the diagnostic imaging agent according to any one of claims 1 to 3.
8. Formula (IA):
   

   

   (In the formula, R ¹ is independently hydrogen atom, fluorine atom, CH _3- , CH ₂ F-, CHF _2- , CF _3- , CH ₃ O-, CH ₂ FO-, CHF ₂ O- or CF ₃ O-, R ² is independently a hydrogen atom or a fluorine atom, A is alkyl, cyano, carboxy, alkoxycarbonyl or R ^3- (CH ₂ ) _m- , and R ³ is hydroxy, carboxy, cyano. , Alkylcarbonyloxy, alkoxycarbonyl, alkoxyalkoxy, hydroxyalkoxy or CONR ⁴ R ⁵ , where R ⁴ and R ⁵ are each independently a hydrogen atom or alkyl, where m is an integer from 1 to 5 (where R). ^{If 1} is both CH ₃ O- or CF ₃ O- and R ² are both hydrogen atoms, then A _{must not be CH 3-} ))) a curcumin derivative or salt thereof.
9. The curcumin derivative according to claim 8, wherein R ¹ is independently a fluorine atom, CH ₂ F- _{, CH F 2-} , CF _3- , CH ₂ FO-, _{CH F 2} O- or CF _{3 O-, respectively.} salt.

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