DK149271B - Betacarboline-3-carboxylic acid derivatives - Google Patents

Description

149271

The invention relates to novel β-carboline-3-carboxylic acid derivatives which are useful in psychopharmaceuticals, being benzodiazepine antagonists.

EP Patent Publication No. 30,254 discloses compounds of the general formula:

S

wherein X represents oxygen, sulfur or NR, wherein R represents the hydrogen or a lower alkyl or cycloalkyl group; o R represents (a) an alkoxy, aryloxy or aralkoxy group, each optionally substituted by one or more halogen atoms, (F, Cl, Br, I), e.g. 1-3 halogen atoms, hydroxy groups, CF 1 groups or alkoxy groups or with an amino, o or (b) NR R, 11 12 wherein R and R are the same or different and each represents (i) hydrogen, (ii) hydroxy, (iii) alkyl, (iv) aryl, (v) aralkyl or (vi) cycloalkyl, wherein the last four (iii-vi) are optionally substituted with a hydroxy, carboxamide, alkoxycarbonyl, carboxy or monosaccharide group or a heterocyclic group, or (vii) amino optionally substituted with all alkyl, aryl, aralkyl or cycloalkyl; or wherein R and R together with the gg neighboring nitrogen atom form a 5-, 6- or 7-membered heterocyclic ring, which may be optionally substituted, under the proviso that R and R cannot both be a 3 hydroxy group; or wherein X and R together represent a single nitrogen atom; 4 R represents hydrogen, an alkyl, cycloalkyl, aralkyl, phenyl or an alkoxyphenyl group containing up to 10 carbon atoms, R 2 represents F, Cl, Br, I, NCL, NR13R14, NHCOR13, CN, 13,13 11 12 13 14 COOR, OR, SCH3 or SOgNR'V, wherein R and R each represent a hydrogen atom or an alkyl group containing up to 6 carbon atoms and optionally substituted with a hydroxy group or a halogen atom (F, Cl, Br, I) and where R and 12 R have the meaning given above,

A

and wherein there may be 1-4 Identical or different R '; g represents hydrogen, or an alkyl or alkoxycarbonyl group, wherein the latter two each contain up to 8 carbon atoms; provided, however: - ΊΊ 12

that R and R cannot both represent a hydrogen atom when X

4 A 9 represents an oxygen atom and R, R and R each represent a hydrogen atom, 11 12 that one of the substituents R and R cannot denote a hydrogen atom when the other substituent represents an amino 4 A 9

and when X represents an oxygen atom and R, R and R

20 each represents a hydrogen atom and that R 4, RA and R 2 cannot each represent a hydrogen atom when 3 X represents an oxygen atom and R represents OCH 2. 1 2 3 4 5 6 7 8 9 10 11

The class of compounds indicated by the above general formula is mentioned as being capable of displacing 3 flunitrazepam from benzodiazepine receptors and, unlike 4 benzodiazepine, chlorodiacepoxide and diazepam, to inhibit aggression 5 without causing impaired motor coordination, which means that 6 compounds of the above general formula are suitable for use 7 as non-sedative anticonvulsants, anti-aggression agents, and 8 anti-anxiety agents or for protection against stress. Therefore, they can be used to treat the following indications:

Anxiety and tension with or without depression, anxiety and disturbance resulting from stress or excessive stimulation as well as pathological aggressiveness.

It has now surprisingly been found that a small group of compounds belonging to the above class, but not specifically mentioned in the above publication, are strong benzodia-zepin antagonists measured by their lack of benzodiaZepin-like pharmacological effects despite their high affinity for benzodiazepine receptors as well as their ability to suppress the effects of benzodiazepines. These properties make the compounds of the present invention extremely useful for e.g. to control and counteract the pharmacological effects resulting from treatment with benzodiazepines and other compounds acting through their affinity for the benzodiazepine receptors.

The compounds of the present invention are β-carboxy-lin-3-carboxylic acid derivatives of the general formula R

H

wherein R represents methyl, ethyl, n-propyl or iso-propyl, and 2 R represents hydrogen, methyl, ethyl, n-propyl or 1 to 2

Isopropyl, provided that R is not methyl when R

denotes hydrogen.

The compounds of the invention can be prepared by the fact that an indole derivative of the general formula R3 25 A f I X

H

Wherein 2 R represents hydrogen, methyl, ethyl, n-propyl or iso-propyl and 3 R represents hydrogen, methyl, ethyl, n-propyl or 3 2

iso-propyl, provided that R is not methyl when R

35 represents hydrogen, cyclized with glyoxylic acid or formaldehyde, then the 1,2,3,4-tetrahydrocarboline derivative thus obtained is dehydrogenated, and if 3 R represents hydrogen, the hydroxy group is etherified by reaction 149271 4 1 1 with a compound of the general formula RX wherein R represents methyl, ethyl, n-propyl or iso-propyl, and X represents a halogen atom.

The compounds of the invention can be used for formulation j. of pharmaceutical preparations, e.g. for oral and parenteral administration in mammals including humans, in accordance with traditional methods of galenic pharmacy.

Traditional additives are such pharmaceutically acceptable organic or inorganic carrier substances which are suitable for parenteral or enteral administration and which do not adversely react with the active compounds.

In general, the compounds of the present invention are dispensed in unit dosage form comprising from 0.05 to 100 mg in a pharmaceutically acceptable carrier per day. unit dose.

The dose of the compounds of the present invention is 0.1-300 mg / day, preferably 1-30 mg / day, when administered to patients, e.g. people, as a drug.

It is well known (Squires, RF and Braestrup, C., Nature (London) 266 (1977), 734) that specific sites in the central nervous system 20 of vertebrates exhibit a specific high affinity for binding of 1,4- and 1,5-benzodiazepines . These sites are called benzodiazepine receptors.

The pharmacological properties of the compounds of the invention have been investigated by determining their ability to displace radiolabeled flunitrazepam from such benzodiazepine receptors as well as their ability to antagonize pentazole-induced seizures.

The displacement activity of the compounds of the invention has been determined by determining the IC

The ICgQ value represents the concentration at which 3q is displaced by 50% of the specific binding of 3 H-flu-nitrazepam (1.0 nM, 0 ° C) in samples comprising a total volume of 0.55 ml of a suspension of brain membrane, e.g. from rats.

The displacement test is performed as follows: 0.50 ml of a suspension of untreated rat brain in 25 mM 33 KH + PO 2, pH = 7.1 (5-10 mg tissue / sample) is incubated for 40-60 minutes at 0 ° C together with 3 H-diazepam (specific activity 14.4 Ci / mmol, 3 1.9 nM) or H-flunitrazepam (specific activity 87 Ci / mmol, 1.0 nM). After incubation, the suspension is filtered through "Whatman GF / C" fiberglass filters, the filter residue is washed twice with cold buffer solution and radioactivity measured by scintillation counting.

The experiment is repeated, prior to the addition of the radiolabelled benzodiazepine, a given amount or excess of the compound whose displaceability is desired is added. Based on the obtained measurement results, the IC ^ value can be calculated.

The ED50 value represents the dose (mg / kg) of a test substance, thereby reducing the specific binding of flunitrazepam to benzodiazepine receptors in a living brain to 50% of the control value. Such an in vivo experiment is performed as follows:

Groups of mice are injected with the test substance at various 10 3 doses and usually subcutaneously. 15 minutes later, H-flunatrazepam is given intravenously to the mice, and after another 20 minutes, the mice are killed and their forebrain membranes are removed and radioactivity in the forebrain membranes is measured by scintillation counting.

The EDc „value is determined from dose-response curves.

15 50

Antagonism of pentazole-induced seizures has been investigated. The study was carried out in accordance with known experimental models in pharmacology, e.g. described in R.A.Turner, Screening Methods in Pharmacology, Academic Press, N.Y. and London 1965, especially p.164 et seq. or Woodbury, P.M., Perry, 20 I.K. and Schmidt, R.P. Antiepileptic Drugs, Raven Press, N.Y. 1,972th

Inhibition of motor coordination in mice was also examined 30 minutes after subcutaneous administration according to a method described in the literature (Buus Lassen et al., Acta Pharmacol, et al.

Toxicol., 1971, 39, 1-16).

25 -

Experimental results obtained by testing some of the compounds of the invention will be apparent from the following Table 1.

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It is clear from the results above that the compounds of the invention very effectively displace H-flunitrazepam from the benzodiazepine receptors, although they do not at all antagonize pentazole-induced convulsions and do not exhibit ataxia properties, which means that they are e.g. do not exhibit the normal anticonvulsant, anxiety-reducing, and sedative effects of benzodlazepines, which is why they are antagonists to these benzodiazepines. (A.S.Lippa, P.A.Nash and E.N.Greenblatt in "Anxiolytics", S.Fielding and H.Lal,

Futura Publishing Co., Inc., New York 1979).

Compared with the prior art known β-carboline compounds mentioned above, the compounds prepared according to the invention have a significantly greater activity as far as the inhibition of the bond H-flunetrazepam is concerned. This can be illustrated by comparing the ED5Q value of the known compound 5-methoxy-β-carboline-3-carboxylic acid ethyl ester with the same value for the closely related novel compound 5-isopropoxy-4-methyl-β-carboline-3 carboxylate. Thus, while the former has an ED₂ value of 37 mg / kg, the latter compound is 0.3 mg / kg, i.e. that the latter compound has an affinity for benzodiazepine receptors that is greater than 100 20 times that of the known closely related compound.

However, the surprising properties of the compounds of the invention are not only that they have this greatly increased affinity for benzodiazepine receptors, but that they do not counteract pentazole-induced convulsions and do not exhibit ataxia properties. Thus, the precursors made according to the invention do not have the normal anticonvulsive, anxiety-suppressing and sedative effects of the benzodiaze pins.

This combined with their strong affinity for benzodiazepine receptors mentioned above causes them to be strong benzodia-3Q zepi n antagonists.

Thus, the unexpected biological effect of the compounds of the invention is that they are potent benzodiazepine antagonists, while the related known compounds are benzodiazepine agonists.

The antagonism effect of the compounds of the invention is further illustrated by testing the effect of one of these compounds, namely 5-isopropoxy-4-methyl-β-carboline-3-carboxylic acid ethyl ester, against benzodiazepine activity in the two in vivo tests in the above table, viz. pentazole-induced convulsions U9271 8 and ataxia.

Antagonism of benzodiazepine action in pentazole-induced seizures in NMRI mice (20-25 g). 5 mg / kg diazepam, administered intraperitoneally 30 minutes before pentazole, completely inhibited the seizures induced with a supramaximal dose of pentazole (150 mg / kg). , administered subcutaneously).

The ability of the present compounds to counteract the effect of benzodiazepine on pentazole-induced seizures has been investigated by determining the ED ^ ED value. The ED ^ g value indicates the concentration of the test compound at which clonic seizures were observed in 50% of the animals treated with 5 mg / kg diazepam 30 minutes before pentazole administration and the test compound 15 minutes before pentazole administration. The experiment was performed as follows: 15 At least 4 groups of mice (10 mice in each group) were injected intraperitoneally with 5 mg / kg diazepam. 15 minutes later, each group of mice was injected intraperitoneally with different doses of the test compound and after a further 15 minutes the mice received 150 mg / kg of pentazole administered subcutaneously. Clonic seizures over the next 20 minutes were noted. From the results obtained, the EDgg value was calculated.

In this experiment, the EDgg value for 5-isopropoxy-4-methyl-8-carboline-3-carboxylic acid ethyl ester was 0.7 mg / kg. 1 2 3 4 5 6 7 8 9 10 11

Antagonism of benzodiazepine action in the absence of motor coordination 2 NMRI mice (20-25 g) were placed on a horizontal wooden rod 4 (4.3 cm diameter) rotating at a speed of 6 min, 8 cm 5 across the table. An intraperitoneal injection of 2 mg / kg lorazepam 30 6 min before the test induced ataxia in all animals, defined as over 3 drops 7 from the rod over 2 min. The ability of the present compounds to counteract the effect of benzodiazepine in motor coordination has been determined by determining the ED 2 -q value. The ED₂ value 10 represents the concentration at which ataxia was observed in 11 50% of the animals treated with the test compound 15 minutes after an intraperitoneal injection of 2 mg / kg lorazepam. The test was performed as follows:

At least 3 groups of mice (8 mice in each group) were injected intraperitoneally with 2 mg / kg of lorazepam. 15 minutes later, each group of mice was injected with different doses of the test compounds and after a further 15 minutes the test for ataxia was performed.

From the results obtained, the EDgQ value was calculated.

In this test, the ED ^ value of 5-isopropoxy-4-methyl-5-carboline-3-carboxylic acid ethyl ester was 1.0 mg / kg.

The preparation of the compounds of the invention will now be described in further detail with reference to the following examples.

Example 1 5-Isopropoxy-4-methyl-B-carboline-3-carboxylic acid ethyl ester A. 5-Isopropoxy-3-ethoxycarbonyl-4-methyl-1,2,3,4-tetrahydro-B-carboline-1-carboxylic acid To a stirred solution of 27.25 g of 2-amino-3 (4-isopropoxyindol-3-yl) butanoic acid ethyl ester in 70 ml of ethyl acetate was added 9.99 g of glyoxylic acid hydrate dissolved in 70 ml of water. The pH of the mixture was adjusted to 4 (10% KgCO 3 solution) and the mixture was further stirred at room temperature for 6 hours. The yellow precipitate was collected by filtration, washed with ethyl acetate and dried.

The organic phase from the filtrate was collected, then dried (Na 2 SO 4) and evaporated.

The crude material obtained, 28.6 g (mp 126-130 ° C decomposition), was used without further purification.

B. 5-Isopropoxy-4-methyl-B-carboline-3-carboxylic acid ethyl ester 20.3 g of 5-isopropoxy-3-ethoxycarbonyl-4-methyl-1,2,3,4-tetrahydro-B-carboline 1-carboxylic acid was refluxed in 450 ml of xylene for 3.5 hours. The mixture was evaporated to give a yellow oil which was dissolved in 250 ml of DMSO. To the solution was added 3.6 g of sulfur and the mixture was stirred at 140 ° C for a total period of 1.5 hours.

The solvent was evaporated and the residue was purified on SiOg with hexane - acetone 1 + 1.

The yield was 8.47 g of 5-isopropoxy-4-methyl-B-carboline-3-carboxylic acid ethyl ester (mp 170-172 ° C).

Similarly, the following compounds were prepared from various tryptophand derivatives.

4-Ethyl-5-methoxy-B-carboline-3-carboxylic acid ethyl ester, m.p.

166-167 ° C.

H9271 5-Isopropoxy-p-carboHn-3-carboxylic acid ethyl ester, m.p. 209 ° C.

Example 2 5-Isopropoxy-4-methyl-Q-carboline-3-carboxylic acid ethyl ester was refluxed with 5 g of 5-hydroxy-4-methyl-β-carboline-3-carboxylic acid ethyl ester in 50 ml of ethanol with 0.25 g of 2-bromopropane. and 0.5 g of 1 CO 2 for 4 hours under Ng atmosphere. The mixture was filtered and evaporated. The residue obtained was purified on SiOg with dichloromethane-ethanol 1000 + 25.

The yield was 0.243 g of 5-isopropoxy-4-methyl-O-carboline-3-carboxylic acid ethyl ester (mp 170-172 ° C).