JPS6110511A - Radiosensitizer for hypoxic cell - Google Patents

Abstract

PURPOSE:To provide the titled sensitizer containing a specific 5-thiotetrazole derivative or its salt as an active component, having excellent radiosensitizing effect to a radiation resistant hypoxic cell causing the recurrence of tumor after radiotherapy, and having low side effect. CONSTITUTION:The objective radiosensitizer for hypoxic cell can be prepared by using the 5-thiotetrazole derivative of formula [R<1> is lower alkyl, phenyl, etc.; R<2> is lower alkyl or -A<2>-COR<4> (A<2> is lower alkylene; R<4> is OH, lower alkoxy, etc.)] or its salt, e.g. 2-[(1-methyl-1,2,3,4-tetrazol-5-yl)thio]acetic acid methyl ester, as an active component. The intermediate cell of tumor under a hypoxic environment is resistant to radiation, and causes the recurrence of tumor after radiotherapy. The compound of formula has strong radiosensitizing activity to hypoxic cell, and excellent tissue transferability and solubility in water, is resistant to inactivation by metabolism, and has low side effect, and accordingly, the compound is useful as a radiosensitizer for hypoxic cell.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hypoxic cell radiosensitizer, and more particularly to a hypoxic cell radiosensitizer containing a 5-thiotetrazole derivative as an active ingredient.

The 5-thiotetrazole derivative which is an active ingredient in the present invention is represented by general formula (I).

N 4', , N, ¥-5-R2, (I) In the formula, R is a lower alkyl group, a phenyl group, or the general formula -A
It shows a group represented by 2-COR4.

<AI represents a lower alkylene group, and R3 represents a hydroxyl group or a lower alkoxyl group. ) R2 represents a lower alkyl group or a group represented by the general formula -A2-COR4. (A
is a lower alkylene group, R4 is a hydroxyl group, a lower alkoxy group, or the general formula R6 is the same or different from each other and represents a hydrogen atom, an optionally substituted lower alkyl group, or a cycloalkyl group, or R5 and R6 represents a piperazino group optionally substituted with a lower alkyl group.

In this specification, the lower alkyl group includes, for example, a linear or branched alkyl group having 1 to 4 carbon atoms,
More specific examples include methyl group, ethyl group, n-propyl group, iso-furovyl group, n-butyl group, 5ec-butyl group, 1so-butyl group, and tert-butyl group. Examples of lower alkylene groups include linear or branched alkylene groups having 1 to 4 carbon atoms, and more specifically, methylene groups, ethylene groups, trimethylene groups, tetramethylene groups, methylmethylene groups, 2 −
Examples include methyltrimethylene group, 2,2-dimethyltrimethylene group, and 1-methyltrimethylene # group. Examples of lower alkoxy groups include alkoxy groups having a linear or branched alkyl group having 1 to 4 carbon atoms, and more specifically, methoxy groups, ethoxy groups, n-propoxy groups, 1so-propoxy groups, etc. group, n-butoxy group, t-butoxy group, etc.

Examples of the substituent in the optionally substituted lower alkyl group include hydroxyl group. Examples of the cycloalkyl group include a cycloalkyl group having 8 to 10 carbon chains, and more specifically, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group,
Examples include a cyclohebutyl group, a cyclooctyl group, a cycloalkyl group, and a cyclodecanyl group.

In general, tumor cells in a hypoxic environment are less sensitive to radiation than when the same cells are in a normoxic (aerobic) environment. Am type Il tumor to some extent [! When the diameter of the tumor is reached, the center of the tumor undergoes so-called central necrosis, and the outermost edge of the tumor maintains good oxygen partial pressure and nutritional supply due to blood circulation, and the tumor cells proliferate vigorously. In the middle between the center and the outermost edge there are cells that survive under hypoxia. Because these intermediate zone cells are under a hypoxic environment, they are more radioresistant than the outermost edge cells, and therefore cause tumor recurrence after radiotherapy. There is a strong desire to strengthen this.

2-nitroimidazole derivatives (J, C,
Atquith, M., Watts et al.
.

Radiat, Res, 60108-118 (
1974)) are known, but at present,
The low-oxygen cotton radiosensitizing effect cannot be said to be sufficient.
Furthermore, 2-nitroimidazole derivatives have various problems such as central toxicity.

Therefore, in order to find a compound that is excellent as a hypoxic cell radiosensitizer, various compounds were synthesized and their effects were investigated. As a result, the 5-thiotetrazole derivative represented by the general formula (I) was found to be a hypoxic cell radiosensitizer. The present invention was completed based on the discovery that it is an excellent product. That is, the 5-thiotetrazole derivative, which is the active ingredient of the present invention, has a strong hypoxic cell radiosensitizing effect, has excellent tissue migration properties and water solubility, and is not inactivated by metabolism.
It is a compound with excellent properties as a hypoxic cell radiosensitizer, such as having few side effects.

It is known that those having a kill group or a phenyl group have an antiulcer effect (Japanese Patent Application Laid-open No. 12286-1986).
No. 2, JP-A-58-82822).

The present inventor conducted a search to develop a new hypoxic cell radiosensitizer, and discovered that the 5-thiotetrazole derivative represented by general formula (I) has an excellent hypoxic cell radiosensitizing effect. I found out.

The compounds of the present invention can be prepared by various known methods (e.g.
122862, Japanese Patent Application Laid-Open No. 58-82822)
For example, the compound (Ia) in which R4 is a compound (Ia) can be produced by the method shown in the following reaction formula.

Reaction formula 1 (in the formula, R represents a hydrogen atom or a lower alkyl group, A2
, R1, R5 and R6 are the same as above. ) Reaction formula 2 (In the formula, X represents a halogen atom, A2, R1, R5
"and R6 are the same as above.) Among the compounds represented by general formula (I), compounds having an acidic group can form a salt with a pharmacologically acceptable basic compound. Examples of such basic compounds include Examples include metal hydroxides such as sodium hydroxide and potassium hydroxide.

Among the compounds represented by general formula (I), compounds having a basic group can easily form salts with ordinary pharmacologically acceptable acids, such as sulfuric acid, nitric acid, hydrochloric acid, etc. , inorganic acids such as hydrobromic acid, and organic acids such as acetic acid, p-toluenesulfonic acid, ethanesulfonic acid, oxalic acid, maleic acid, succinic acid, and benzoic acid.

The 5-thiotetrazole derivative represented by the general formula (I) and its salt can be administered orally or parenterally. That is, it can be administered orally in commonly used dosage forms such as tablets, capsules, syrups, suspensions, etc., or it can be administered orally in the form of solutions, emulsions, suspensions, etc. It can be administered parenterally in the form of It can also be administered rectally in the form of a skewer.

The appropriate dosage forms also include acceptable conventional carriers,
It can be manufactured by blending the active compound with excipients, binders, stabilizers, and the like. Furthermore, when used in the form of an injection, acceptable buffers, solubilizing agents, isotonic agents, etc. may be added. Dosage and frequency of administration depend on symptoms, age,
Although it varies depending on the body weight, administration form, etc., it is usually recommended to give about 0.1 to 100 v per day per body weight IKq for adults.

The pharmacological effects of the sensitizer of the present invention will be explained below with reference to test examples.

Test compound (1) 2-((1-methyl-1,2,3,4-tetrazol-5-yl)thio]acetic acid methyl ester (2) N-(2-hydroxyethyl)-2-(1- Methyl-1,2,8,4-tetrazol-5-yl)thio-
Acetamide (8) N-(n-propyl)-2-(1-methyl-1,
2,8,4-tetrazol-5-yl)thio-acetamide + 4)N-(2-hydroxyethyl)-2-(1-phenyl-1,2,8,4-tetrazol-5-yl)thio-acetamide (5) 2-(5-mercapto-1,2,8,4-tetrazol-1-yl)acetic acid methyl ester 6) N,N-diethyl-2-(1-methyl-1°2.
8.4-tetrazol-5-yl)thio-acetamide (7) N-sita-hexyl-2-(1-methyl-1,2
,8,4-tetrazol-5-yl)thio-acetamide (8) 5-(morpholinocarbonylmethylthio)=1-
Methyl-1,2,8,4-tetrazole (9) 5-(4-methylpiperazinocarbonylmethylthio)-1-methyl-1,2,8,4-tetrazole radiosensitization test method.

In mammalian cell culture, the survival rate determined by the formation of viable cell colonies after a predetermined treatment is used as an index, and radiation irradiation is carried out in anaerobic and aerobic environments with and without the addition of the drug.

The relationship between radiation dose and survival rate under these four conditions (four conditions can be set by combining the above two conditions) was determined, and the toxicity and anaerobic effects of the drug under aerobic and anaerobic conditions were determined. Hypoxic cell radiosensitization effect of the drug under conditions (Enhancementratio)
was calculated.

(E, R,) was able to be obtained.

Test Results - Table 1 shows the results of determining the in vitro sensitizing effect.

Table-1 Acute toxicity after intraperitoneal administration to mice The results of determining (LD50) are shown in Table 2.

Table 2 Next, the method for producing the 5-thiotetrazole derivative represented by the general formula (1), which is the active ingredient of the present invention, will be explained with reference to production examples.

[ts Preparation Example 1) 2-((1-methyl-1,2゜3.4-
Tetrazol-5-yl) thio]acetic acid methyl ester 1-methyl-5-mercapto-1,2,8゜4-tetrazole sodium salt 6.90f in acetonitrile 50
In addition to -, 5.20 - of 2-bromoacetic acid methyl ester was gradually added dropwise.

Thereafter, the mixture was stirred at room temperature for 1 hour. After removing the insoluble matter, the solvent was distilled off under reduced pressure, and the residue was purified by silica gel column chromatography using chloroform as an eluent to obtain the title compound 8.479 as white crystals.

Melting point 47-48°C NMR (CDC1B) δ (p, p, m,): 8
．． 7B (8H, S).

8.96 (8H, s), 4.06 (2H, s) [Production Example 2 JN-(2-hydroxyethyl)-2-(1-methyl-1,2,8°4-tetrazol-5-yl) Thioacetamide 2-((1-methyl-1,2,8,4-tetrazole-
5-yl)thio]acetic acid methyl ester 5.19f was dissolved in acetonitrile 5o-, and 2-aminoethanol 5.
osy was processed and stirred at room temperature for 5 hours. Thereafter, the solvent was distilled off under reduced pressure, and the residue was dissolved in chloroform/methanol 9515.
The title compound 4.2Of white crystals was purified by silica gel column chromatography using as an eluent.
I got it.

Melting point 58.5-54.5°C NMR (da-DMSO) a (p, p, rn,)
: 2.97-8.51 (4H, m), 8.95 (
8H, S), 4.01 (2H, 8), 4.60 (tH,
t), 8.17 (IH, br) [Production Example 3) -N-(n-propyl)-2=(1-methyl-1,2,8,4-tetrazol-5-yl)thio-acetamide 2 -((1-methyl-1,2,8,4-tetrazole-
5-yl)thio]acetic acid methyl ester 6,Of was dissolved in 50m of acetonitrile, and n-propylamine 9.4f was dissolved.
was added and stirred at room temperature for 8 hours. Thereafter, the solvent was distilled off under reduced pressure, and the residue was dissolved in chloroform/methanol 98/2 ft.
Purification by silica gel column chromatography as an eluent gave 5.8 g of the title compound as white crystals.

Melting point 86.0-86.5°C NMR (CDC1a) a (p, p, m,):
0.87 (8H, t), 1.50 (2H, m), 8.
20 (2H, q), 8.91 (2H, S), 8.94 (
8H,S), 7.09(IH,br) [Production Example 4) N-(2-hydroxyethyl)-2-(1
-phenyl-1,2゜3.4-tetrazol-5-yl)thio-acetamide 1-phenyl-5-mercapto-1,2゜8.4-tetrazole 1.78y,) ethylamine 1.21F in acetonitrile 80 In addition to -, 1.58N of 2-bromoacetic acid methyl ester was gradually added dropwise, and the mixture was stirred at room temperature for 7 hours.

Thereafter, the solvent was distilled off under reduced pressure, and the residue was purified by column chromatography using chloroform as the eluent to obtain white crystals of 2-((1-phenyl-1,2,8,4-tetrazol-5-yl)thio). Acetic acid methyl ester 1.7
9g was obtained. .

Melting point 814.0-85.0'C NMR (CDCIs) a (p, p, m,):
8.77 (3H,s), 4.21 (2H,s), 7.
54(5H,s) 2-((1-
phenyl-1,2,8,4-tetrazol-5-yl)
[thio]acetic acid methyl ester 3. Of and 2-aminoethanol 4,4f were added to 80% acetonitrile and stirred at room temperature for 10 hours.

Thereafter, the solvent was distilled off under reduced pressure, and the residue was purified by silica gel column chromatography using chloroform/methanol 9515 as an eluent to obtain the title compound 8.21 as white crystals.

Melting point 95-96°C NMR (d+, -DMSO) δ(1)4+, m,):
8.17 (2H, t), 8.89 (2H, t), 4.1
8 (2H, S), 4.64 (IH, t), 7.68 (5
H,s), 8.29 (IH,t) [Production Example 5) 2-
(5-methylthio-1,2゜3.4-tetrazole-1
-yl) Acetate methyl ester 2-(5-mercapto-1,2,8,4-tetrazol-1-yl)acetic acid 6.4f in acetonitrile 200mg
To the mixture were added 12.49 f of anhydrous potassium carbonate and 12.8 f of methyl iodide, and the mixture was stirred at 70°C for 8.5 hours.

After returning to room temperature, insoluble materials were removed and the solvent was distilled off under reduced pressure. The residue was purified by silica gel chromatography using chloroform as the eluent to obtain the title compound 6 as a yellow liquid.
．． I got 91.

NMR (CDC1a) a (p, p, m,): 2
．． 81 (8H, S), 8.81 (8I (, S), 5.0
2(2H,5) nD=1.5188 [Production example phrase N,N-diethyl-2-(1-methyl-1
,2,8,4-tetrazol-5-yl)thio-acetamide 2-(l-methyl-1,2,8,4-tetrazol-5
-yl)thio-acetic acid1. Thionyl chloride 10- was added to Of and stirred at 50°C for 80 minutes. After removing excess thionyl chloride by distillation under reduced pressure, anhydrous benzene is added to the residue and azeotroped to remove the remaining thionyl chloride. The residue was dissolved in tetrahydrofuran 5
- and added dropwise to a solution consisting of diethylamine 2- and tetrahydrofuran 20- under ice cooling. After the addition was completed, the mixture was stirred at room temperature for 1 hour. Thereafter, the solvent was distilled off under reduced pressure, and the residue was purified by silica gel column chromatography using chloroform as an eluent to obtain 0.861 of the title compound as a yellow liquid.

NMR (CDC1a) a (p, p, m,) 21
．． 15 (8H, t), 1.27 (8H, t), 8.48
(4H, q), 8.98 (8H, s), 4.48 (2H
,s) nD="1.5247 [Production Examples 7 to 9] The following compounds are obtained in the same manner as in Production Example 6 using appropriate raw materials.

[7] N-cyclohexyl-2-(1-methyl-1,2
, 8,4-tetrazol-5-yl) thio-acetamide white crystals (eluted with chloroform/methanol 40/1) m, I), 112-114°C NMR (CDCI a) δ (p, p, m, ): 1
．． 09-1.84 (IOH, m), 8.78 (IH, m
) 8.88 (2H, s), 8.96 (8H, s) 6.9
2(IH, bs) (8) 5-(morpholinocarbonylmethylthio)-
1-Methyl-1,2,8,4-tetrazole white crystals (eluted with chloroform/methanol 20/1) m, p, 109-111°C NMR (CDC1a) δ (p-p, m): 8.6
1-8.76 (8H, m), 198 (8H, S)4.
40(2H,5) (9) 5-(4-Methylpiperazinocarbonylmethylthio)-1-methyl-1,2°8.4-tetrazole white crystals (eluted with chloroform/methanol 10/1) m, p , 87-88℃

Claims (1)

[Claims] General formula▲ Numerical formula, chemical formula, table, etc.▼ [In the formula, R^1 represents a lower alkyl group, a phenyl group, or a group represented by the general formula -A^1-COR^3 . (A^1 represents a lower alkylene group, and R^3 represents a hydroxyl group or a lower alkoxy group.) R^2 represents a lower alkyl group or a group represented by the general formula -A^2-COR^4. (A^2 is a lower alkylene group, R^4 is a hydroxyl group, lower alkoxy group, or a group represented by the general formula ▲ Numerical formula, chemical formula, table, etc. available▼, and R^5 and R^6 are the same or Differently represents a hydrogen atom, an optionally substituted lower alkyl group or a cycloalkyl group, or R^
5 and R^6 are bonded to each other and represent a piperazino group which may be substituted with a morpholino group or a lower alkyl group. )] A hypoxic cell radiosensitizer containing a 5-thiotetrazole derivative or a salt thereof as an active ingredient.