RU2052456C1 - 3-methyl-n-[2-(4-phenylpiperazino)-ethyl]-benzamide hydrochloride showing neuroleptic activity and 3-methyl-n-[2-(4-phenylpiperazino)-ethyl]-benzamide as a parental compound for its synthesis - Google Patents

Abstract

FIELD: organic chemistry. SUBSTANCE: product: 3-methyl-N-[2-(4-phenylpiperazino)-ethyl]-benzamide hydrochloride of the formula

, empirical formula is C₂₀H₂₆ClN₃O, m. p. is 214-215 C, base empirical formula is C₂₀H₂₆N₃O, m. p. is 135-135.5 C. Reagent 1: 2-bromoethylamine hydrobromide. Reagent 2: 3-methylbenzoic acid chloroanhydride. Reagent 3: 1-phenylpiperazine. Reaction conditions: in the medium of inert organic solvent. EFFECT: improved method of synthesis. 3 cl, 4 tbl

Description

(I) обладающему нейролептической активностью, и 3-метил-N-[2-(4-фенилпиперазино)этил] бензамиду в качестве исходного соединения в синтезе гидрохлорида 3-метил-N-[2-(4-фенилпиперазино)этил]бенза- мида.The invention relates to new chemical compounds 3-methyl-N- [2- (4-phenylpiperazino) ethyl] benzamide hydrochloride of formula I

(I) possessing neuroleptic activity, and 3-methyl-N- [2- (4-phenylpiperazino) ethyl] benzamide as a starting compound in the synthesis of 3-methyl-N- [2- (4-phenylpiperazino) ethyl] benzene hydrochloride mida.

CH

Данное соединение является эталонным препаратом из группы производных бензамида.Structural analogues are known, for example, benzamide derivatives metaclopramide, which has weak antipsychotic activity. Known structural analogue antipsychotic agent N- (1-ethyl-2-pyrrolidinylmethyl) -2-methoxy-5-sulfamoylbenzamide (sulpiride) [1] of the formula
H ₂ NO ₂ S

CH

This compound is a reference preparation from the group of benzamide derivatives.

 The aim of the invention is the creation of a new compound that is superior in activity and therapeutic breadth to a structural analogue of such an action and having an original psychopharmacological and neurochemical profile.

 Example 1. 3-Methyl-N- [2- (4-phenylpiperazino) ethyl] benzamide.

To a solution of 11.3 g (0.055 mol) of 2-bromoethylamine hydrobromide in 20 ml of dichloroethane and 30 ml of water, 17.5 g (0.165 mol) of sodium carbonate are added, stirred for 30 minutes, cooled with ice water outside and 8.5 g (0.055) are added. mol) of 3-methylbenzoic acid chloride dissolved in 10 ml of dichloroethane with stirring. The reaction mixture is left for a day, filtered, the filter cake washed with chloroform, the filtrate is removed with chloroform, the extract is dried over magnesium sulfate, the solvent is distilled off in vacuo. The oily crude residue of 3-methylbenzoic acid 2-bromoethylamide is dissolved in 30 ml of toluene, 8.9 g (0.055 mol) of 1-phenylpiperazine are added and boiled for 11 hours, the reaction mixture is cooled, extracted with 10% hydrochloric acid, the acidic extract is washed with ether, the ether solution is separated, and the acidic is made alkaline with soda until alkaline (pH ≥ 10). Extracted substance is extracted with ether, the ethereal solution is dried with potash. After partial distillation of the ether (to a total volume of about 25 ml) and cooling, a crystalline substance is isolated, which is filtered off and, after recrystallization from acetone, 8.4 g (47.5%) are obtained (I) with mp 135-135,5 ^C. Found, C 77,21; H 7.75; N, 12.93. C ₂₀ H ₂₅ N ₃ O. Calculated C 74.27; H 7.79; N, 12.99.

 PRI me R 2. 3-Methyl-N- [2- (4-phenylpiperazino) ethyl] benzamide hydrochloride.

5 g of 3-methyl-N- [2- (4-phenylpiperazino) ethyl] benzamide are dissolved in 50 ml of absolute ether and hydrochloride is precipitated with an ethereal solution of hydrogen chloride (to pH 2-3), the precipitate is filtered off, 4.95 g are obtained (89%) hydrochloride (I) with so pl. 214-215 ^about C (from abs. Alcohol). Found, C, 66.68; H 7.26; Cl 9.71; N, 11.65. C ₂₀ H ₂₆ ClN ₃ O. Calculated C 66.74; H 7.28; Cl 9.85; N, 11.68.

To a solution of 4.4 g (0.0285 mol) of 3-methylbenzoic acid chloride in 50 ml of dry dichloroethane at room temperature was added a suspension of 6.73 g (0.025 mol) of N '- (2-ethylamino) -N-phenylpiperazine carbonate in 30 ml of dry dichloroethane, while there is a slight heating of the reaction mass. The reaction mixture was stirred for 2 hours at a bath temperature of 50-60 ^{° C,} the end temperature of the water bath is brought to reflux and maintained for 5 minutes. At the end of the exposure, the reaction mass is cooled to room temperature and incubated for 20 hours, the precipitate formed is filtered off, recrystallized from abs. alcohol and get 6.1 g (67.7%) of the hydrochloride (I) with so pl. 214.5-215 ^about S.

 Biological tests.

 1. Apomorphine verticalization in mice.

 After 30 min of adaptation of mice, apomorphine was administered at a dose of 1 mg / kg subcutaneously in individual wire nets. Over the next 30 minutes, the position of animals was recorded every 5 minutes. The degree of "verticalization", i.e. mouse location on a vertical cell wall was scored. The results are presented in table 1.

 As follows from Table 1, compound (I) inhibited the effect of apomorphine, which manifests itself in stimulation of animal verticalization, starting with a dose of 5 mg / kg. At a dose of 20 mg / kg, compound (I) produced an effect similar to that of sulpiride at a dose of 50 mg / kg. The anti-apomorphine effect of compound (I) in this test indicates the presence of antipsychotic activity in this compound.

 2. Apomorphine hyperactivity of rats in the "open field".

 For 3 min, horizontal motor activity was recorded in the RODEO-1 automated installation. After 3 minutes, retesting was performed. At the same time, a sharp decrease in the indicator was observed in the control, which indicates the adaptation of rats. The administration of apomorphine at a dose of 1 mg / kg subcutaneously 3 minutes before repeated testing led to an increase in horizontal motor activity.

 Compound (I) in doses of 5 mg and higher (Table 1) suppressed apomorphine hyperactivity, while the effect of the minimum effective dose of compound (I) 5 mg / kg was approximately 4 times higher than the effect of sulpiride at a dose of 50 mg / kg.

 3. Apomorphine stereotype in rats.

 The experiments were carried out in rectangular mesh chambers. The following types of stereotypes were evaluated: verticalization (paws on a grid), sniffing, licking, biting, biting. All types of stereotypes were evaluated simultaneously, every 2 min for 60 min, the start of observation immediately after administration of apomorphine at a dose of 2 mg / kg subcutaneously. In the experiment, animals were taken that showed during preliminary testing at least 10 points according to the criterion of verticalization. Saline or test substances was administered 30 minutes before apomorphine. At a dose of 5 mg / kg, compound (I) did not affect the intensity of stereotypes, and at a dose of 20 mg / kg, the effect of apomorphine was approximately halved, which corresponds to the effect of sulpiride at a dose of 50 mg / kg (Table 1).

 4. Test apomorphine yawning.

 The experiments were performed on rats in standard plexiglass houses; evaluated the number of yawns for 60 minutes arising in response to the administration of apomorphine in a small ("presynaptic") dose of 0.1 mg / kg subcutaneously.

 As follows from Table 1, at a dose of 5 mg / kg, compound (I) reduces the amount of yawning caused by apomorphine by 10 times. At a dose of 20 mg / kg, compound (I) completely eliminated the indicated action of apomorphine. Sulpiride at a dose of 50 mg / kg reduced the effect of apomorphine by approximately three times.

 5. Assessment of cataleptogenic activity in rats.

 After 2, 1 and 4 hours after administration of the substance, each animal was placed on a flat surface. The absence of spontaneous movements indicated the presence of akinesia. If after pushing the animal did not begin to move, it was assigned 1 point. Further testing was carried out by placing the front paws of the rat on a cube 3 cm high, in turn. Preservation of the attached pose for more than 10 s was estimated at 0.5 points for each paw. The same with a cube 9 cm high was rated at 1 point. Thus, the maximum number of points for one animal was 4 points. At a dose of 100 mg / kg, compound (I) (Table 1) showed a moderate cataleptogenic effect. As you know, sulpiride does not have a cataleptogenic effect in doses up to 120 mg / kg.

 6. The study of the effect of substances on the content of monoamines and their metabolites in the brain of rats.

 The content of norepinephrine (HA), dopamine (DA), 5-hydroxytryptamine (5-OT), dioxyphenylacetic acid (DOPUK), 5-hydroxyindoleacetic (5-OIAA) and homovanilinic (HVA) acids were determined in the following brain structures: the frontal cortex, hypothalamus, nucleus accumbens, striatum (striatum). The test substances were administered to animals intraperitoneally 30 minutes before decapitation. Isolated brain regions were homogenized in 0.1 N perchloric acid with dioxibenzylamide added as an internal standard. After centrifugation, the supernatant was used to determine monoamines and their metabolites by high performance liquid chromatography with electrochemical detection (HPLC / ED). The data are presented in table.2.

 From the table. 2, it follows that compound (I) at a dose of 20 mg / kg had a more pronounced effect on the content of monoamines and their metabolites than sulpiride at a dose of 50 mg / kg, and a number of qualitative differences were found. So, unlike sulpiride, compound (I) caused a moderate decrease in the content of norepinephrine and dopamine in the studied parts of the brain. Both compound (I) and sulpiride increased the rate of dopamine metabolism in the hypothalamus and striatum. The effect of compound (I) on the content and metabolism of serotonin (5-RT) was found mainly in the nucleus accumbens, and sulpiride in the hypothalamus and cortex.

 The revealed qualitative differences in the effect of compound (I) and the atypical antipsychotic sulpiride on the metabolism parameters of monoamines served as the basis for comparing compound (I) with the classical antipsychotic haloperidol, which was used at a dose of 1 mg / kg equipotential, 50 mg / kg sulpiride according to a number of behavioral tests. Table 2 presents data indicating that, according to the effect on the content of norepinephrine in the hypothalamus and metabolic rate in the nucleus accumbens, compound (I) is close to haloperidol, although it differs from the latter in the absence of an effect on the cortex of dopamine and the content and metabolism of serotonin in the striatum.

 7. Test substance (I) for tyrosine hydroxylase test "in vitro".

Vysokoizbiratelnyh tirozingidroksilazny test [2] for the initial screening of substances with structure neuroleptics, based on a particular their property to eliminate Substrate inhibition of tyrosine hydroxylase enzyme [3] thus it is possible to distinguish atypical neuroleptics from typical for influencing the K _m of tyrosine that when testing results in a reduction rate reactions with optimal substrate concentration in the presence of atypical antipsychotics. To test substance (I) in this test, highly purified TG from rat hypothalamus was used, the reaction rate was determined spectrophotometrically [4] The results are presented in Table 3. It can be seen from Table 3 that compound (I) eliminated substrate inhibition of TG, like haloperidol and sulpiride: the reaction rate at an inhibiting tyrosine concentration (220 μM) in the presence of these substances is comparable to the reaction rate at the optimal tyrosine concentration. At the same time, at the optimal tyrosine concentration (30 μM), compound (I), like the atypical antipsychotic sulpiride, inhibits the reaction. Thus, the compound (I) in the tyrosine hydroxylase test manifests itself as an atypical antipsychotic.

 8. Effect on the release of dopamine and DOPUK from fragments of rat striatum.

 Table 2 presents the results of a study of the effect of compound (I), sulpiride, and haloperidol on the release of dopamine and DOPUK, as determined by HPLC / ED in a buffer medium washing fragments of rat brain striatum. Animals were injected with test substances at doses of 20, 50, and 1 mg / kg, respectively, 30 minutes before decapitation. The effect of substances was evaluated under conditions of depolarization of the striatum fragment membranes caused by potassium ions (30 mM). The results obtained indicate that compound (I), similar to haloperidol, did not significantly affect the release of dopamine and its metabolite DOPUK. Sulpiride enhanced dopamine release stimulated by potassium ions.

In in vitro experiments carried out with the addition of test substances directly to the incubation medium of striatum fragments (Table 4), it was found that compound (I) increases the K ⁺ -stimulated release of DOPUK, dopamine sulpiride, and haloperidol does not change the emitted indices.

 9. The study of toxicity.

Experiments to determine acute (single administration) toxicity were performed at room temperature on male white mice weighing 20-21 g. The substances were administered intraperitoneally in the form of a suspension with the addition of Tween-80. The experimental results were taken into account after 24 hours. The LD ₅₀ value was calculated by the Lichfield-Wilcoxon method [5]. The LD ₅₀ for compound (I) was 150 mg / kg. If we take into account that the effective antiapomorphine dose of compound (I) according to Table 1 turned out to be 5 mg / kg, then the value of its therapeutic index, defined as the ratio of the average lethal dose to the average effective, is 30, which indicates a large therapeutic latitude the actions of the described compound. It is known that LD _{50 of} sulpiride for mice is 372 mg / kg for the subcutaneous route of administration, therefore, its therapeutic index is about 7.

 Thus, the results of studying the pharmacological properties of the new compound in the in vivo and in vitro and ex vivo experiments allow us to characterize compounds (I) as a substance with a high biological activity and an action profile characteristic of antipsychotic drugs. According to the majority of standard tests used, primarily apomorphine ones, which have high predictive value for detecting antipsychotic activity, compound (I) was significantly more active than sulpiride (not less than 10 times), while the breadth of the therapeutic effect of compound (I) is also several times more than sulpiride. Compound (I) is significantly more active in influencing dopamine biosynthesis and metabolism specific for the action of antipsychotics.

 All this allows us to attribute compounds (I) to potential antipsychotics, i.e. substances exhibiting antipsychotic properties.

The inhibitory effect of compound (I) in tests such as apomorphine-induced verticalization, horizontal motor hyperactivity, yawning, indicate a selective effect on the mesolimbic dopaminergic system. The combination of the pronounced effect of compound (I) on yawning with relatively low activity according to the apomorphine stereotype test indicates the possible selectivity of the effect of compound (I) on presynaptic dopamine receptors that are superior to that of sulpiride, which is considered one of the most specific antagonists of presynaptic dopamine D ₂ -type receptors.

 The cataleptogenic effect of compound (I), which reflects the possible extrapyramidal potential in the clinic, is small and appears only at a dose of 100 mg / kg, which is 20 times higher than the average effective dose.

 According to standard apomorphine tests, the most informative for detecting antipsychotic activity, compound (I) is several times more active than sulpiride, for example, at a dose of 5 mg / kg, similar to sulpiride at a dose of 50 mg / kg, halves apomorphine verticalization in mice, and is equally effective in suppressing apomorphine hyperactivity in rats at doses of 2.5 and 50 mg / kg, respectively.

 In general, the average effective doses of hydrochloride (I) are 10 times lower than sulpiride, and the breadth of the therapeutic effect is 4 times greater.

Claims (2)

1. The hydrochloride of 3-methyl-N- [2- (4′-phenylpiperazino) ethyl] benzamide of the formula

possessing antipsychotic activity.  2. 3-Methyl-N- [2- (4-phenylpiperazino) ethyl] benzamide as a starting compound in the synthesis of 3-methyl-N- [2- (4-phenylpiperazino) ethyl] benzamide hydrochloride.

Images