WO1991006529A1

WO1991006529A1 - Glutamic and aspartic acid derivatives with antigastrin activity and a method for their preparation

Info

Publication number: WO1991006529A1
Application number: PCT/EP1990/001808
Authority: WO
Inventors: Francesco Makovec; Claudio Lucio Rovati; Angelo Luigi Rovati
Original assignee: Rotta Research Laboratorium S.P.A.
Priority date: 1989-11-02
Filing date: 1990-10-25
Publication date: 1991-05-16
Also published as: AU6637690A; DE69015208T2; EP0498830B1; ATE115550T1; CA2067569A1; IT1238664B; EP0498830A1; ES2066232T3; IT8967937A1; DE69015208D1; PT95766A; IT8967937A0; JPH05501411A

Abstract

Glutamic and aspartic acid derivatives having general formula (I), in which n is 1 or 2, R1 is a phenyl group mono- or di-substituted with chloro, methyl or nitro groups such that hydrogen or the nitro group may be present in positions (2 and 6) of the phenyl group and hydrogen, chloro or the methyl group may be present in positions (3 and 5), and in which R2 is a linear or branched alkyl chain or a cyclo-alkyl group containing from 5 to 9 carbon atoms, the stereochemistry at the chiral centre marked with an asterisk in formula (I) being DL or D, and their pharmaceutically acceptable salts, useful for the therapeutic treatment of conditions induced by hypergastrinaemia. The compounds of the invention in fact show powerful antigastrin ('little gastrin' or G-17) and antipentagastrin activities.

Description

Glutamic and aspartic acid derivatives with antiqastrin activity and a method for their preparation The subject of the present invention is glutamic and aspartic acid derivatives and their use for the preparation of medicaments for the therapeutic treatment of disorders induced by hypergastrinaemia. These derivatives are representated by the general formula indicated below:

CO OH

(CH₂)n

(*) CH-NH-CO-R- (I)

I

CO-NH-R,

in which n is 1 or 2 , R, is a phenyl group mono- or di-substituted with chloro, methyl or nitro groups such that hydrogen or the nitro group may be present in positions 2 and 6 of the phenyl group and hydrogen, chloro or a methyl group may be present in positions 3 and 5, and in which R₂ is a linear or branched alkyl chain or a cyclo-alkyl group containing from 5 to 9 carbon atoms, the stereochemistry at the chiral centre marked with an asterisk in formula (I) being DL or D, including their pharmaceutically acceptable salts.

In particular, the preferred compounds within the scope of the invention are those described specifically in tables A and D below and their pharmaceutically acceptable salts, the compounds most preferred being those in which n is 2, R, is selected from the group consisting of 3-chlorophenyl and 3,5-dichlorophenyl and

R is selected from the group consisting of 3,3-dimeth lbutyl, 4,4-dimethylpentyl and 3,3-methyl- ethylpentyl.

The compounds of the present invention display powerful antagonistic activities towards gastrin ("little gastrin" or G-17) and towards pentagastrin which is its biologically active terminal peptide sequence.

Gastrin is a polypeptide hormone secreted by the cells of the antral and duodenal mucosae, its secretion being induced, in particular, by a nervous mechanism through vagal excitation.

Once secreted, gastrin flows, via the bloodstream to the parietal cells situated mainly in the mucosa fundica and, by binding to the membrane receptors of the cells, activates them. This activation initiates the formation of HC1 and its secretion into the gastric cavity.

Hyperactivity of this system results in the hypersecretion of gastric acid which may have consequences harmful to the organism.

The compounds of the present invention belong to a more general class of glutamic and aspartic acid derivatives which are generally described in U.S. Patent A-4 791 215 in the name of the Applicant. Amongst the various activities mentioned with reference to the class of compounds which is the subject of the above patent, those relating to their powerful activities in inhibiting cholecystokinin (CCK) in various experimental models were of particular value. For example, the compound designated C-7 (lorglumide) inhibited the contraction induced by CCK-8 (lOng/ml) in guinea-pig gall bladders in vitro by 50% at a concentration of 0.06 mcg/ml, which is approximately 15 times greater than that of the antagonist. The compounds described specifically in the above patent were, however, inactive or only slightly active as inhibitors of pentagastrin (see, for example Eur. J.

Med.Chem. (1986)-21, pp. 9-20) even though gastrin is closely related to CCK since the C-terminal pentapeptide Gly-Trpt-Met-Asp-PheNH_ is common to the two polypeptides. This led to the assumption that they interacted mainly with the tripeptide sequence

CCK-(26-28) without interfering with the receptor structure which is responsible for the interaction with the terminal pentapeptide sequence CCK-(29-33) which is common to the two hormones CCK and gastrin, which is thus the opposite of what takes place with the compounds of the subject invention, which have powerful antigastrin activities and little or no activity against CCK.

The present invention therefore arises from the following considerations: the anti-CCK activities of the compounds of the patent mentioned above are due to the simultaneous presence of an acid group which acts as a solubiliser and of 3 suitably sized and spaced lipophilic units, that is, two alkyl substituents (corresponding to two R₂ groups in formula I) and a suitably substituted phenyl ring (corresponding to the substituent R, in formula I) .

In order to obtain compounds with high antigastrin activities, however, as in the case of the compounds of the invention, the presence of the acid group and of the phenyl ring (R,) with suitable substituents (which do not, however, coincide with those of the other series, that is, with the anti-CCK compounds) are still necessary, whilst the presence of only one hydrophobic alkyl group of suitable length and steric bulk is essential at R₂.

A further subject of the present invention is the use of the derivatives of formula (I) in which n, R. and R„ have the meanings defined above, and their pharmaceutically acceptable salts, for the preparation of a medicament for the therapeutic treatment of conditions induced by hypergastrinaemia.

As already mentioned, the compounds of the invention have powerful and specific antigastrin activities in various experimental models, both in vivo and in vitro. In fact, at little more than nanomolar concentrations, the most powerful of these inhibit the binding of pentagastrin tritiate to the gastric mucous glands of guinea pigs and to the cortical membranes of mice.

In vivo, they show high activities against the secretion of acid, blocking the secretory stimulus induced by pentagastrin in a dose-dependent manner. This activity is specific since the compounds which are the sbuject of the invention do not block secretions induced, for example, by carbachol or histamine.

The compounds can thus be used, to advantage, in the treatment and prevention of various disorders in man in which it is advantageous to block the stimulant activity of gastrin, for example, ulcers or gastro-duodenitis resulting from excessive gastric secretion induced by a hypergastrinaemic condition, in Zollinger-Ellison syndrome, or in the treatment of several forms of tumour which are sustained by hypergastrinaemi .

On the basis of their powerful activities displayed as inhibitors of the binding of gastrin at the level of the CNS, the compounds in question could also display activity towards some kinds of mental disorders attributable to an imbalance in the physiological neuron levels of gastrin or other bioactive peptides related thereto.

The method of preparing the derivatives of the invention with chiral centres in the DL form is characterised by the following steps which may be represented thus:

a) reacting an internal anhydride of formula:

C0-

(CH₂)n

CH-NH-CO-R.

CO

in which n and R- have the meanings given above, with a primary amine of formula R₂~NH₂, in which R« has the meaning given above, in a molar ratio of from 1 to 5, in a solvent such as water, ethyl acetate, dioxan, acetonitrile, tetrahydrofuran or a mixture thereof, at a temperature of between -20 C and 30 C and recovering the compounds of formula I from the reaction mass by fractional crystallisation or other conventional methods .

The following example is given in order better to illustrate the invention.

Preparation of ( — )-4-[(3-chlorobenzoyl)-amino]-5-(3, 3-dimethylbutylamino)-5-oxopentanoic acid (compound A-5 in Table Z)

26.8g (0.1 moles) of 3-chlorobenzoyl glutamic anhydride were loaded into a reactor and suspended in 100 ml of water. The suspension was cooled to approximately 5 C and 25.3g (0.25 moles) of 3,3-dimethylbutylamine were added dropwise over a period of approximately 15 minutes. The mixture was left to react for 3 hours at this temperature and then acidified with glacial acetic acid. It was filtered, washed with water until neutral and dried. The crude product obtained was crystallised from alcohol/H₂0 (3:2). 19.6 g were obtained. Yield 53%. M.P.: 194-195°C. TLC (isoamyl alcohol-acetone-H₂0:5/2/l - V/V) : Rf. 0.78.

Table A below shows, by way of example, many examples of these compounds with some of their identifying characteristics, as well as the yields obtained.

TABLE A: derivatives (DL-series) having the formula:

The method for the preparation of the derivatives of the invention with chiral centres in the D form is characterised by the following steps, which may be represented thus:

a) reacting the gamma-benzyl ester of N-carbobenzoxy- D-glutamic acid with an amine of formula R₂- H₂, in which R_? has the meaning given above, by the mixed anhydride method, in an inert anhydrous solvent, at a temperature of between -15 and +15 to give compounds of formula (III) ; (see the scheme below)

b) debenzylating and decarbobenzoxylating the compound of formula (III) dissolved in an inert solvent by reacting it with hydrogen at ambient temperature and atmospheric pressure, in the presence of a catalytically effective quantity of a hydrogenation catalyst to obtain derivatives of formula (II) (see the scheme below) ;

c) reacting the derivatives of formula (II) under Schotten-Baumann conditions with an equivalent quantity of an acyl chloride of formula R..-C0C1, in which R, has the meaning given above, at a temperature of from 0 to 15 C and recovering the D-4-acylamino-5-alkylamino- 5-oxopentanoic derivative of formula (I) from the reaction mass.

The sequence of steps of the method according to the invention is illustrated as a whole by the following scheme:

COOH CO-NH-R,

(step a) III

HYDROGENATION, COOH ACYLATION COOH

I I

(CH₂) ₂ R -CO-C1 (CH₂) ₂

(step b) CH-NH, (*) CH-NH-CO-R..

CO-NH-R, (step c) CO-NH-R,

(ID (I)

(*) chiral centre in the D form.

The amidation step (a) is carried out at a temperature preferably of between -15 C and -10 C for a period of from 1 to 24 hours, preferably for 6 hours, with the reagents in a stoichiometric ratio. The preferred solvent for the reaction is selected from chloroform, dioxan and tetrahydrofuran.

The hydrogenation step (b) is preferably carried out in the presence of a quantity of between 0.02 and 0.001 atoms of palladium per mole of compound (III) , supported on carbon, in a methanolic solution, at ambient temperature and pressure, in a stream of hydrogen and for a period of from 1 to 12 hours, preferably for 3 hours. The acylation step (c) is preferably carried out at a temperature of approximately 5 C, over a period of from 1 to 24 hours, preferably for 12 hours.

The following examples are given in order better to illustrate the invention.

Example 2

Preparation of the benzyl ester of D-4-carbobenzoxyamino-5-(3,3-dimethylbutylamino)-5-oxo- pentanoic acid (compound B, of Table B) .

37.1g (0.1 moles) of the gamma-benzyl ester of N-carbobenzoxy-D-glutamic acid was dissolved in 250 ml of anydrous tetrahydrofuran, the solution was cooled to -10 C and 10.1 g (0.1 moles) of triethyalmine were added under agitation: 10.8g (0.1 moles) of ethyl chlorocarbonate were then added, still at -10°C. The temperature was kept at -10 C for 20 minutes and 10.1 g (0.1 moles) of 3,3-dimethylbutylamine were then added. The mixture was left under agitation for a further 6 hours, the temperature rising to ambient temperature; the mixture was evaporated to dryness and the residue taken up with ethyl acetate.

This was washed with 2N HC1, sodium bicarbonate and finally water and then dried over anhydrous Na₂S0₄. By concentration to a small volume, an oily residue was obtained (mw 454.5) which crystallised spontaneously upon standing. The crude product obtained was crystallised from dioxan-water (1:1). TLC: Rf 0.78 [methylene chloride-alcohol 9/1 (V/V) ] . Melting point: 104-106°C .

35.0 g were produced. Yield 77%.

All the compounds of formula III were synthesised by the same method (see the schemes above) . Table B below gives some of the compounds thus obtained with some of their identifying characteristics.

TABLE B Derivatives having the formula:

COO CH,

I Y7

(CH₂)₂

I

CH-NH-COO CH„- i /^■

I v/

CO-NH-R,

(1) eluent: Methylene chloride/alcohol (9:1)

(2) eluent: Chloroform/ethyl acetate (9:1)

Example 3

Preparation of D-4-amino-5-(3,3-dimethylbutyl-5- oxopentanoic acid (Compound C.. in Table C) .

45.4g (0.1 moles) of the benzyl ester of D-4-carbobenzoxy-amino-5-(3,3-dime h lbutyl)-5- oxopentanoic acid (Compound B.,) were dissolved in 300 ml of methanol to which 1 g of 10% palladiated carbon had been added and hydrogenated at ambient temperature with a stream of hydrogen for 3 hours. The catalyst was filtered out and the methanol distilled under vacuum. An oily residue (mw 286.4) was obtained which crystallised upon standing and had a chromatographic purity of more than 95%. TLC: Rf 0.62 [n-butanol-acetic acid-H.--0 5/2/2 (V/V) ] . Melting point: 132-133°C.

18.6 g were produced. Yield 81%.

All the compounds of formula II were synthesised by the same method (see scheme) .

Table C below gives the compounds thus obtained with some of their identifying characteristics.

TABLE C Derivatives having the formula:

CO-NH-R,

(*) eluent: n-Butanol-Acetic Acid-H₂0 (5-2-2/V:V)

Example 4

Preparation of D-4-(3-chlorobenzoylamino)-5-(3,3- dimethylbutylamino)-5-oxopentanoic acid (Compound D-1 in Table D) .

23.Og (0.1 moles) of D-4-amino-5-(3,3-dimethylbutyl-5- oxopentanoic acid (Compound Cl) were suspended in 300 ml of water and then dissolved under agitation by the addition of 10.6g (0.1 moles) of sodium carbonate. 17.5 g (0.1 moles) of 3-chlorobenzoyl chloride were then added over a period of 1 hour at 0 C under agitation.

The mixture was left to react for 12 hours.

It was acidified to Congo red with dilute HC1 and the precipitate thus formed was filtered. Crystallisation was carried out with isopropyl ether/ethyl acetate (3:2) .

M.P.: 129-132°C. TLC (isoamyl alcohol-acetone-H₂0: 5/2/1/) : Rf 0.78.

29.5 g were obtained (mw 368.9). Yield 80%.

Rotatory power: [alpha] _ - 1.90°C (c = 4.0% in methanol) .

All the compounds of formula I (see scheme) were synthesised by the same method.

Table D below gives the compounds thus obtained with some of their identifying characteristics, as well as the yields obtained. In order to check the optical purity of the compounds produced by the stereo-conservative synthesis described above, HPLC analysis was carried out with the use of a

Macherey-Nagel Resolvosil/-BSA 7 column as the stationary phase and 0.1M phosphate buffer (pH 8) + 5% n-propanol as the mobile phase.

The compounds given in Table D showed an optical purity of more than 95% in all cases. The retention times are given in the table.

TABLE D: derivatives (D-Series) having the formula:

CO-NH-R_^

(1) isolated as the calcium salt.

(2) L-series shown for comparison.

The anti-acid-secretion activities of the compounds of the invention, displayed through an antigastrin mechanism, were analysed by means of a series of pharmacological tests, both in vitro and in vivo, and are documented below.

Studies on binding to isolated guinea-pig stomach glands.

The capacity of some of the compounds which are the subject of the invention to inhibit the binding of pentagastrin-[beta-alanyl-3-3H(N) ] to the gastrin receptor sites on the parietal cell membranes of the fundic mucosa of a guinea-pig stomach was evaluated by comparison with the displacement of pentagastrin induced by proglumide, which is a reference antigastrin compound, by lorglumide, which is a powerful CCK antagonist mentioned above, and by the compound D5 which is the optical antipode (the L-series enantiomer) of the compound DI.

Male guinea pigs weighing about 400-500g were used. After the guinea pig had been killed, its stomach was removed and placed in oxygenated SPB buffer at 37 C (SPB = saline phosphate buffer: 149.6 mM NaCl, 3 mM K₂HP0₄, 0.64 mM NaH₂P0₄, pH 7.3).

After washing in the buffer, the stomach was placed on a petri dish and the antral part discarded.

The mucosa of the remaining part was removed from the underlying muscular part and was then chopped and transferred to a flask containing a collagenase digestion solution, 0.1% BSA and 0.2% glucose. The solution was incubated at 37 C for 10 minutes under agitation and a stream of 0,,.

During the incubation period, the tissue was passed several times through a series of pipettes with decreasing diameters in order to facilitate its digestion. At the end of the period, the tissue was removed and centrifuged at 1000 rpm. The supernatant liquid resulting from the centrifuging was discarded and the pellet washed several times with a washing buffer containing EDTA to remove the collagenase.

The glands were then isolated from the undigested tissue by conventional techniques, suspended in Hepes buffer for binding and incubated together with a - radioactive tracer and the compounds under test for 30 minutes at 25°C.

After the supernatant liquid had been removed by centrifuging, the radioactivity associated with the pellet was determined with a liquid scintillator. The specific binding was determined as the difference between the binding in the absence and in the presence

— a of 10 M pentagastrin.

The results obtained are shown in Table 1 which gives the IC50, that is, the concentration (in moles/litre) of the antagonist which can displace 50% of the pentagastrin tritiate from the receptor.

TABLE 1 : Inhibition of the binding of pentagastrin

[beta-alanyl-3-3H(N) ] - to isolated guinea-

Note (1) : these compounds were tested for comparison.

It can be seen from the data given in the table that the compounds which are the subject of the invention antagonise the binding of pentagastrin by 50% in molar ccoonncceennttrraattiioonnss ooff between 10 and 10 , depending on their structures.

The most active compounds achieve this activity at a molar concentration of around 5 x 10 —8 and thus about

100 times greater than that of the specific antagonist

(cold pentagastrin) , thus showing a high specificity of action. Proglumide, which is an antigastrin reference drug, is approximately 10000 times less active than the most powerful compounds of the series whilst lorglumide, which is a specific antagonist of CCK, is about 200 times less active. The compound D5, which is an L-series derivative, is about 10 times less active than the corresponding compound DI which is its

D-series enantiomer.

Studies on binding to cerebral cortex membranes of mice

The displacement capacities of some of the compounds of the invention which were most active in the experimental model described above were to be evaluated but, in this case, with the use of the central gastrin receptors as the substrate. Cerebral cortex membranes were therefore used and pentagastrin tritiate was again used as the ligand.

Mouse cortex tissue was homogenised cold in 20 volumes of tris buffer (pH 7.7). After washing and centrifuging, the final pellet was resuspended in 20 volumes of binding buffer containing, inter alia, TRIS, BSA and bacitracin. 0.4 ml of the membrane thus obtained were then incubated with a radioactive tracer and with the compounds under test for 40 minutes at

37°C.

After the supernatant liquid had been removed by centrifuging, the radioactivity associated with the pellet was determined, again with a liquid scintillator. The specific binding is the difference between the binding in the absence and in the presence of 10~ M pentagastrin.

The results obtained are shown in Table 2. Again, this gives the IC50s of the compounds tested with the meaning as given above.

It can be seen from the data given in Table 2 that the most active of the compounds of the invention have IC50s of the order of magnitude of 10 —8M. Their relative potencies are unchanged from those described above for binding to the gastric glands. In fact, the most active compounds are about 100 times less powerful than the specific antagonist (pentagastrin) and about

100 times more powerful than the CCK-antagonist, lorglumide. In this case, the D-series derivatives

(compound Dl) are again about 10 times more active than the corresponding L-enantiomers (compound D5) . As well as helping to show that the central and peripheral gastrin receptors seem to have a common structure, these results may be of practical interest since they predict a possible favourable use for the products of the invention in the treatment of cerebral disorders attributable to imbalances in the physiological neuron levels of- gastrin. TABLE 2 : Inhibition of the binding of pentagastrin

[beta-alanyl-3-3H(N) ] - to mouse cortical membranes.

Note (1) : these compounds were tested for comparison,

In or er to con rm t e ant gastr n act v ty shown by these in vitro studies, the compounds of the inventon were also studied in vivo, through the experimental model described below.

Antisecretive activity in anaesthetised rats

The antisecretive activity was determined in rats with the use of male animals weighing about 200g, anaesthetised with urethane. Gastric secretion was stimulated with pentagastrin. K.S. Lai's method (Gut 5, (1964), 327-341) was used, with slight modifications.

After tracheotomy, oesophageal and duodenal cannulae were inserted. A tepid solution (37 C) of 0.25 mM NaOH was perfused through the stomach by means of a peristaltic pump at a constant flow rate of 1 ml/minute. After stabilisation for 20 minutes, the dose of the stimulant, indicated in Table 3, dissolved in a physiological solution, was perfused for 120 minutes at a rate of 0.95 ml/hour. After 60 minutes of perfusion (basic stimulation) , the products under test were administered intravenously (I.V.) in boli whilst the perfusion of the stimulant continued for a further 60 minutes. The acid secretion was recorded continuously as a function of time.

The activity of the product was evaluated as the reduction in the secreted acidity after administration of the product as a percentage of the basic acidity measured during the first 60 minutes of collection during which only pentagastrin was present.

The antagonistic compounds tested were administered in different doses so that an ID50 (that is the dose (in mg/Kg I.V.) which can inhibit the effect of the pentagastrin by 50% could be calculated.

The results thus obtained are given in the following table in which the activities of the compounds are expressed as ID50s under the stimulus of pentagastrin at 30 mcg/Kg/h.

TABLE 3 : Antagonistic activity (ED50 mg/kg IV) towards

gastric acid secretion induced by pentagastrin (30 mcg/kg/h)

The antigastrin activity was particularly favourable in the case of the glutamic acid derivatives (n = 2) , when R. was 3-chlorophenyl or 3,5-chlorophenyl, or when the alkyl group in R~ had a length of at most 4 or 5 carbon atoms and was sufficiently branched at its (distal) end remote from the secondary amide group.

It should be noted that the compounds of the invention which were most' active in this experimental model are about 15 times more active than the reference antigastrin compound, proglumide. It is also interesting to note that the CCK antagonist, lorglumide, was completely inactive up to a dose of 100 mg/Kg.

The action of these compounds against gastric secretion is specifically linked to their antigastrin activity. In fact they have no anticholinergic or antihistamine activity (anti H₂) since they were completely inactive when carbachol (30mcg/Kg/h) or histamine (2.3 mg/Kg/h) was used as the stimulant in the experimental model described above.

The activity of the compounds of the invention seems even more remarkable if one takes account of their low toxicity. For example, the compound DI has an LD50 IV in mice of approximately 600mg/Kg. The toxic dose (LD50) in this case is therefore about 20 times greater than the antigastrin dose (ID50) .

Anticholecystokinin (anti-CCK) activity

In order to check the hypothesis that the molecular conformation of the subject compounds is suitable to give them a specific antagonistic activity towards gastrin and not towards CCK, the anticontracturant activity of some of the compounds of the invention was tested on guinea-pig gall bladders stimulated in vitro by CCK-8.

A longitudinal strip of guinea-pig gall bladder was placed in a bath for isolated organs in the presence of Krebs at a temperature of 32 C, continuously oxygenated by an oxygen-C0₂ mixture (95-5 V/V) .

The isometric contractions were detected by means of a force transducer and recorded.

The gall bladder was contracted with the use of a lOng/ml concentration of CCK-8; the antagonistic activity of the compounds towards the contracturant effect of the CCK was determined with the use of different concentrations and the IC50 value, that is, the concentration in mcg/ml of the compound which is able to antagonise the contracturant effect of the CCK by 50%, thus determined.

The results obtained are set out in the table below which gives the compounds tested and the IC50s which were calculated by the regression method on a set of at least three tests for each compound investigated.

Table 4: Anti-CCK activity (concentration 10 ng/ l) expressed as the IC50 in mcg/ml on guinea-pig gall bladder in vitro.

COMPOUND IC50 ACTIVITY (mcg/ml)

Al > 100 A7 > 100 A13 32 A20 > 100 DI 83 Lorglumide 0.06

An examination of the table shows that the compounds claimed antagonise the contracturant activity of CCK-8 at a concentration such that the contracturant activity of the most active of the derivatives tested, the compound A13, was about 500 times greater than that of lorglumide, which shows that they have little or no anti-CCK activity.

The inhibiting effect on the rate of pentagastrin- induced growth of normal and tumorous colic cells

Gastrin has a trophic effect on the digestive epithelium. The chronic administration of gastrin (or pentagastrin, the biologically active part of the physiological hormone) to rats thus causes hyperplasia of the fundic mucosa and of the colic mucosa. Recently it has been shown that gastrin stimulates the growth of a transplantable mouse colic tumour produced by chemical induction (Winsell et al. -Surgical Forum,

33, 384 (1982) .

On the basis of this premise, it was desired to investigate whether the specific gastrin antagonists of the invention could antagonise the growth of experimentally induced gastrointestinal tumours.

A gastrin antagonist of the invention which was one of the most active in the tests described above, that is the compound A-5, was selected for this purpose. Male mice weighing 20-25g were inoculated subcutaneously in

4 the interscapular region with a suspension of 8 x 10 tumour cells of a mouse colic adenocarcinoma.

5 groups each of 10 animals were used, that is : one control group of animals, one group of animals treated with 250 mcg/ml of pentagastrin twice a day and two groups of animals treated with the compound A-5 in doses of 15 and 30 mg/Kg i.p. respectively, twice a day, plus pentagastrin in the manner described above.

After 20 days, the animals were killed and the fundic mucosa and the tumours were removed, weighed and extracted in order to determine their DNA content. The results obtained are given in the following table.

Table 6 : Antagonistic activity of the compound A-5 on pentagastrin-induced colic tumorous growth

The data in Table 6 show that pentagastrin induces a significant hyperplasia of the fundic mucosa and a significant increase in the weight of the colic tumour and in its DNA content. The compound A-5 can inhibit both of the aforesaid trophic effects of pentagastrin in a significant and dose-dependent manner.

Claims

1. Glutamic and aspartic acid derivatives having the general formula:

CO OH

I I

(CH₂)n

I I

(*) CH-NH-CO-R. (I)

C0-NH-R

in which n is 1 or 2, R-. is a phenyl group mono- or di-substituted with chloro, methyl or nitro groups such that hydrogen or the nitro group may be present in positions 2 and 6 of the phenyl group and, independently, hydrogen, chloro or the methyl group may be present in positions 3 and 5, and in which R₂ is a linear or branched alkyl chain or a cyclo-alkyl group containing from 5 to 9 carbon atoms, the stereochemistry at the chiral centre marked with an asterisk in formula (I) being DL or D, and their pharmaceutically acceptable salts.

2. A derivative of glutamic acid according to Claim 1 in which R.. is selected from the group consisting of 3-chlorophenyl and 3,5-dichlorophenyl, R₂ is selected from the group consisting of 3,3-dimethylbutyl, 4,4-dimethylpentyl and 3,3-methyl-ethylpentyl, the stereochemistry of the chiral centre being DL or D, and their pharmaceutically acceptable salts.

3. Compounds according to Claim 1, that is: DL-4-[ (3-chlorobenzoyl)-amino]-5- pentylamino)-5-oxo- pentanoic acid;

DL-4-[ (3-chlorobenzoyl)-amino]-5- 3-methylbutylamino) -

5-oxopentanoic acid;

DL-4-[ (3-chlorobenzoyl)-amino]-5- hexylamino)-5-oxo- pentanoic acid;

DL-4-[ (3-chlorobenzoyl)-amino]-5- 3,3-dimethylbutyl- amino)-5-oxopentanoic acid;

DL-4-[ (3-chlorobenzoyl)-amino]-5- 3-methylpentylamino) -

5-oxopentanoic acid;

DL-4- [ (3-chlorobenzoyl)-amino]-5- cyclohexyla ino)-5- oxopentanoic acid;

DL-4- [ (3-chlorobenzoyl)-amino]-5- heptylamino)-5-oxo- pentanoic acid;

DL-4-[ (3-chlorobenzoyl)-amino]-5- 4,4-dimethylpentyl)-

5-oxopentanoic acid;

DL-4- [(3-chlorobenzoyl)-amino]-5- 3,3-dimethylpentyl- amino)-5-oxopentanoic acid;

DL-4-[ (3-chlorobenzoyl)-amino]-5- 3-ethylpentyl)-5-oxo- pentanoic acid;

DL-4-[ (3-chlorobenzoyl)-amino]-5- cycloheptylamino)-5- oxopentanoic acid;

DL-4-[ (3-chlorobenzoyl)-amino]-5- 4-methylpentylamino)-

-5-oxopentanoic acid;

DL-4-[ (3-chlorobenzoyl)-amino]-5- 3,3-methylethyl- pentylamino)-5-oxopentanoic acid;

DL-4-[ (3-chlorobenzoyl)-amino]-5- 3,3-diethylpentyl- a ino)-5-oxopentanoic acid;

DL-4-[ (3-chlorobenzoyl)-amino]-5- 2-(dicyclo[2.2.1]- heptyl)-ethylamino)-5-oxopentanoic acid;

DL-4-[ (3-chlorobenzoyl)-amino]-5-(3,3-methylethyl-4- methylpentylamino)-5-oxopentanoic acid;

DL-4- [ (3,5-dichlorobenzoyl)amino]-5-(3,3-dimethylbutyl- amino)-5-oxopentanoic acid;

DL-3-[ (3-chlorobenzoyl)-amino]-4-(3,3-methylethyl- pentylamino)-4-oxobutanoic acid;

DL-3-[ (3-chlorobenzoyl)-amino]-4-(cycloheptylamino)-4- oxobutanoic acid;

D-4-[(3-chlorobenzoyl)-amino]-5-(3,3-dimethylbutyl- amino)-5-oxopentanoic acid;

D-4-[(3-chlorobenzoyl)-amino]-5-(4,4-dimethylpentyl- amino)-5-oxopentanoic acid;

D-4-[ (3-chlorobenzoyl)-amino]-5-(3,3-methylethyl- pentylamino)-5-oxopentanoic acid;

D-4-[ (3-chlorobenzoyl)-amino]-5-(cycloheptylamino)-5- oxopentanoic acid; and their pharmaceutically acceptable salts.

4. A pharmaceutical composition including at least one of the compounds according to any one of Claims 1 to 3 or a pharmaceutically acceptable salt thereof as the active agent and a pharmaceutically acceptable vehicle.

5. The use of glutamic and aspartic acid derivatives according to Claim 1 or a pharmaceutically acceptable salt thereof for the preparation of a medicament for the therapeutic treatment of disorders induced by hypergastrinaemia.

6. The use of a derivative according to Claim 1 for the preparation of a medicament for the therapeutic treatment of ulcers.

7. The use of a derivative according to Claim 1 for the preparation of a medicament for the therapeutic treatment of tumorous conditions sustained by gastrin and by other bioactive polypeptides related thereto.

8. The use of a derivative according to Claim 1 for the preparation of a medicament for the treatment of pathological conditions of the CNS linked to an imbalance in the physiological neuron levels of gastrin or other bioactive polypeptides related thereto.

9. A method for the preparation of a glutamic acid or aspartic acid derivative of formula (1), in which n, R₁ and R₂ have the meanings given in Claim 1 and in which substituents at the chiral centre (marked with an asterisk) have the DL conformation, characterised in that it comprises the steps of:

a) reacting an internal anhydride of formula (2) :

C0-

(CH₂)n I

0

CH-NH-CO-R, I (ID

I I

CO

in which n and R, have the meanings given above, with a secondary a ine of formula R₂~NH₂, in which R₂ has the meaning given above, in a molar ratio of from 1 to 5, at a temperature of from -10 C to 10 C, and recovering the compounds (I) from the reaction mass.

10. A method for the preparation of a glutamic acid or aspartic acid derivative of formula (I) in which n, R₁ and R₂ have the meanings given in Claim 1, and in which the substituents at the chiral centre (marked with an asterisk in formula (I)) have the (D) conformation, characterised in that it comprises the following stereo-conservative steps: a) reacting the gamma-benzyl ester of

N-carbobenzoxy-D-glutamic acid with an amine of formula H₂-NR₂, in which R₂ has the meaning given above, by the mixed anhydride method, at a temperature of between -15° and +15° and in an inert anhydrous solvent and recovering the compounds (III) from the reaction mass;

(III)

"•--x- H-CO-O-CH

I -= Y_7

C0-NH-R₂

b) debenzylating and decarbobenzoxylating the compound of formula (III) dissolved in an inert solvent, such as methanol, by reacting it with hydrogen at ambient temperature and pressure in the presence of a catalytically effective quantity of hydrogenation catalyst and recovering the compounds (II) from the reaction mass;

COOH

(CH₂) ₂

I I (ID

CH-NH₂

I I

C0-NH-R₂

c) reacting the derivatives of formula (II) under Schotten-Baumann conditions with an equimolecular quantity of an acyl chloride of formula R.-C0-C1, in which R, has the meaning given in Claim 1, at a temperature of from 0 to 15 C and recovering the derivatives of formula (I) with the D conformation from the reaction mass.