NO743260L - - Google Patents

Description

Method for producing a DL7or

L- tr yp.to f ansa l t

In DT-OS 2 224 130 certain derivatives of tryptophan in L-, DL- and D-forms are described, which can be denoted by the formula

where R can be

1) a phenyl group which is mono- or poly-substituted in the ortho-, meta- or para-positions with substituents selected from the class comprising Cl, Br, F, I, CN, NO2, NH2, OH, OCH3, COCH, COOC2H5, CH3, C2H5andCF3, 2) a mono- or polysubstituted hydroxybenzyl group with substituents selected from the same class as indicated under 1), 3) a mono- or polysubstituted benzyl group with substituents selected from the class indicated under 1), or

4) a hydroxynaphthyl group,

and where R1 can be

A) a hydroxyl group,

B) an aniline group which in the para position has a carboxyl group or a carboxyl group which is esterified with an aliphatic C..-C., linear or branched alcohol, benzyl alcohol or a phenol such as e.g. ordinary phenol or 2,4-dichlorophenol, C) an amino group substituted with a phenylacetic acid group as such or esterified with one of the alcohols listed under B), or D) an alkoxy group ending with a secondary or tertiary amino group, either free or converted to salt with a mineral acid such as hydrochloric acid or an organic acid such as citric or oxalic acid.

These compounds exhibit interesting pharmacological properties in relation to mammals. One of these properties is a high antispasmodic effect on the smooth muscle system in the digestive tract. Another property is a regulatory effect on the secretion of digestive secretions, especially an inhibitory effect on the secretion of secretions in the case of excessive secretion. Yet another property is a protective and scarring effect on stomach and intestinal mucosa. The above-mentioned compounds can therefore be used with advantage in various diseases of the human digestive system which are caused by disturbances in the secretion of digestive secretions, cramps and damage to the mucous membrane, e.g. duodenal ulcers, peptic ulcers or colon inflammation.

It has now been discovered that Na, Ca, Mg and Al salts of certain particular derivatives of formula (1) exhibit surprisingly superior pharmacological properties.

The present invention thus relates to the salts of DL- and L-tryptophan derivatives with the formula

where X is Na, Ca, Al or Mg, n is 1, 2 or 3 corresponding to the valence of X and R is a p-chlorobenzoxy or p-chlorophenyl group.

Particularly valuable salts are the Na and Ca salts of N-p-chloro-benzoyl-L-tryptophan and the Na and Ca salts of N-p-chlorobenzoyl-DL-tryptoph an.

According to the invention, a pharmaceutical preparation has also been obtained, especially in unit dosage form, comprising a salt as defined above and a pharmaceutically acceptable carrier for this.

According to the invention, the salts with the formula (II) can advantageously be prepared directly from DL- or L-tryptophan.

More specifically, an aqueous solution of DL- or L-tryptophan is brought to a pH value above 7 by the addition of sodium hydroxide or carbonate and reacted with an essentially stoichiometric amount of p-chloro-benzoyl chloride or p-chloro-carbobenzoxy chloride dissolved in a organic solvent which is miscible with water, at a temperature of 14-18°C with stirring until a clear solution is obtained. The preferred organic solvent is tetrahydrofuran. At the end of the reaction, the solvent is extracted with the aid of another organic solvent which is mainly immiscible with water, e.g. ethyl acetate or isopropyl ether, after which the remaining aqueous solution containing the sodium salt of the formula (II) is optionally reacted with a slight stoichiometric excess (up to approx. 10%). of a mineral salt of Ca, Mg or Al with stirring, whereby / the desired salt of N-p-chlorobenzoyl- or N-p-chloro-carbobenzoxytryptophan is obtained. The mineral salt is preferably a chloride, but other raineral salts such as e.g. sulfates and carbonates can be used. The calcium salts of the tryptophan derivatives are preferably produced in the above-mentioned manner mainly because they precipitate from the mother liquor and can thus be easily recovered. The sodium salts do not precipitate easily and can be recovered by concentration of the above-mentioned, remaining aqueous solution in vacuum and subsequent addition of propanol-2 until the salt is precipitated.

Example 1 N-p-chlorobenzoyl-L-tryptophan calcium salt (CR 501-calcium salt)

40.8 g (0.2 mol) of L-tryptophan are suspended in 100 ml of deionized water mixed with 8 g (0.2 mol) of NaOH tablets dissolved in 200 ml of deionized water. The temperature of the resulting solution is reduced to 13-14°C, and in the course of 1-3 hours (preferably about 2 hours) 26 ml (0.2 mol) of p-chloro-benzoyl chloride dissolved in 80 ml of tetrahydrofuran are added dropwise

and 200 ml of 1N NaOH into the solution. The reaction temperature is kept at between 14 and 18°C during the dripping. Stirring is carried out for 12 hours, and the temperature is not allowed to drop below 14°C to avoid the formation of a precipitate.

The resulting solution is shaken twice for 15 minutes with respectively 250 ml of ethyl acetate and 250 ml of isopropyl ether, the organic phase being emptied each time. A solution of 12.0 g of CaCl2 (0.11 mol) in 200 ml of deionized water is quickly dropped into the remaining aqueous solution at room temperature.

After completion of dripping, the reaction mass is stirred at room temperature for at least two hours to allow the formed precipitate to increase its volume appropriately. The filtered precipitate is taken up twice with respectively 600 and 400 ml of deionized water and filtered and dried in an air oven at 90°C for 12 hours. 68.2 g of salt are obtained.

Yield 90%. Melting point 280-285°C with slow decomposition.

The salt comprises 2 molecules of crystal water. Crystallizes from a mixture of 2 parts by volume acetone with 3 parts by volume water. Very slightly soluble in water. Soluble in methanol, ethanol and acetone.

Example 2

N- p- chloro- benzyloxycarbonyl- L- tryptophan calcium salt ( CR 44 9- calcium salt)

The procedure corresponds to that in example 1. Instead of p-chloro-benzoyl chloride, 41.0 g (0.2 mol) of p-chloro-carbobenzoxy chloride is used there. 62.6 g of product is obtained. Yield 84%. Melting point 217-221°C with slow.

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decomposition. Crystallizes from aqueous acetone (volume ratio 1:1). Very slightly soluble in water. Soluble in methanol and ethanol.

Example 3 N-p-chloro-bezoyl-L-tryptophanmagheslumsaIt (CR 501-magnesium salt)

Example 1 is repeated, with 22.3 g (0.11 mol) of MgCl 2 6 H 2 O being used instead of calcium chloride. 63.0 g of product is obtained. Yield 89%. Melting point 210-215°C with slight softening. Crystallizes from aqueous acetone (volume ratio 1:1). Very slightly soluble in water. Soluble in methanol and ethanol.

Example 4

Example 1 is repeated, with 15.9 g (0.066 mol) of AlC13<*>6H20 being used instead of calcium chloride. 63.0 g of product is obtained. Yield 88%. Melting point. 18 8-19 5°C with slow decomposition. Crystallizes from aqueous acetone. Very slightly soluble in water. Soluble in methanol and ethanol.

Example 5

M-p-klOr-behzOyl-L- tryptophan sodium salt ( CR 5 01 sodium salt)

Example 1 is repeated to the point where the aqueous solution is shaken with ethyl acetate and isopropyl ether and the organic phase is poured off.

The remaining aqueous solution containing the desired sodium salt is concentrated in vacuum until a syrup-like mass is obtained, after which 100 ml of propanol-2 is poured into the mass. A precipitate forms almost immediately, and this is filtered and dried in an air circulation oven at 60°C for 12 hours. 60.4 g of product is obtained. Yield 83%. Melting point 228-231°C. Crystallizes from propanol-2. Soluble in water up to approx. 5% concentration by weight. Very soluble in methanol, ethanol and acetone.

Example 6

N- p- chloro- benzyloxycarbonyl- L- tryptophan sodium salt (CR 44 9- sodium salt)

Example 5 is repeated, with 41.0 g (0.2 mol) of p-chlorocarbobenzoxychloride being used instead of p-chlorobenzoyl chloride. 58.9 g of product is obtained. Yield 74%. Melting point 224-227°C. Crystallizes from propanol-2. Soluble in water up to approx. 25 percent by weight. Very soluble in methanol, ethanol and acetone.

Example 7

N- p- chlorobenzoyl- DL- tryptOfah calcium salt ( CR 663- calcium salt)

Example 1 is repeated, with DL-tryptophan being used instead of L-tryptophan. 69.0 g of product is obtained. Yield 91%. Melting point above 280°C.

Crystallizes from acetone. Almost insoluble in water. Barely soluble

in methanol and ethanol.

Example 8

N-p-chloro-benzoyl-DIi-tryptophan sodium salt (CR 663-sodium sa 11)

Example 5 is repeated, with DL-tryptophan being used instead of L-tryptophan. 61.8 g of product is obtained. Yield 86%. Melting point 225-228°C. Crystallizes from propanol-2. Soluble in water up to approx. 40%. Very soluble in methanol and ethanol.

Example 9

N-p-chloro-behzyloxycarboryl-DL-tryptophan calcium salt ( CR 4 63- calcium salt) Example 1 is repeated, with DL-tryptophan being used instead of L-tryptophan and 41.0 g (0.2 mol) of p-chloro-carbobenzoxychloride being used instead of p-chloro- benzoyl chloride. 64.1 g product is obtained. Yield 85.9%. Melting point 2 36-240°C with slow decomposition. Crystallizes from a mixture of acetone and water (volume ratio 7:1) . Very slightly soluble in water. Soluble in methanol and ethanol.

Pharmacological effect

Tables 1-3 serve to highlight the most interesting pharmacological properties of the salts described above.

It will be understood that the symbols in the tables in accordance with the preceding description have the following meaning:

CR 501: N-p-chloro-benzoyl-L-tryptophan

CR 663: N-p-chloro-benzoyl-DL-tryptopham

CR 44 9: N-p-chloro-benzoyloxycarbonyl-L-tryptophan

CR 463: N-p-chloro-benzyloxycarbonyl-DL-tryptophan

The symbols CR 501, CR 449 and CR 463 are also used in the same

meaning in the initially mentioned-DT-OS 2 224 130.

In table 1, the antisecretory action of the described salts of CR 501, CR 449, CR 663 and CR 463 is indicated. The antisecretory effect is defined as the dose in mg/kg body weight of the animal which reduces gastric secretion by 50%. The assessment is carried out" by considering the reduction in the amount of secreted gastric juice in relation to comparison trials.

Rats with an average weight of 200±20 g are used, the lower part of the stomach being ligated at the level of the gastric port in order to collect the gastric juice in the specified time periods.

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The preparations are taken orally in the form of aqueous suspensions.

The table shows that the antisecretory effect of CR 501 begins before 5 hours have passed from administration_and lasts up to 15 hours with a gradual decrease.

The effect of the CR 501 sodium salt begins earlier, specifically already in the second hour, possibly as a result of the higher solubility in the body fluids due to the fact that the sodium salt is water-soluble in contrast to CR 501.

The effect of the calcium, aluminum and magnesium salts is delayed, but lasts longer.

In Table 2, the protective effect of CR 501, CR 663,

CR 449 and CR 463 as well as salts thereof specified. The effect is defined as the dose in mg/kg body weight of the animal that prevents damage caused by indomethacin in 50% of the treated individuals.

Indomethacin is given orally to rats with an average weight of 200+20 g at a dose of 16 mg/kg. After 4 hours, all comparison subjects have bleeding ulcers.

The protective preparations are administered through the mouth in aqueous suspension.

Table 2 shows that CR 501 is effective in preventing gastric damage from indomethacin. However, the indicated salts have an improved activity, probably as a result of a longer residence time in the cells of the mucous membrane.

This effect is not exerted by the cation, as this is only present in a very small amount by weight in each salt. Administration of other salts of calcium or aluminum which contained the cation in amounts up to 10 times as large as in the salts of CR 501 actually has no therapeutic effect on these experimentally produced gastric ulcers.

In table 3, the anticonvulsant effect of CR 501 and its salts is indicated;

The antispasmodic effect is determined on mice with an average weight of 22±3 g by administering a suspension of charcoal in gum arabic and examining after two hours whether the charcoal had reached the beginning of the large intestine. In untreated individuals, the charcoal reaches exactly this point. When a drug acts as an anticonvulsant, it slows the passage rate of the charcoal. The assessment of the results is expressed as ED^q in mg/kg body weight

of the animal, i.e. the dose at which the charcoal in 50% of the treated animals has not reached the large intestine.

Table 3 shows that CR 501 is effective as an anticonvulsant even when administered orally as a water-insoluble powder.

The same applies to the similarly water-insoluble salts of calcium, aluminum and magnesium. A significantly better effect is shown by the sodium salt when it is administered intraperitoneally in aqueous solution (considering that this salt is water-soluble).

Compared to the other salts and CR 501, the sodium salt has the advantage of a higher antispasmodic effect when introduced parenterally, so that immediate treatment may be necessary in urgent cases.

In summary, it can be stated that table 1 shows that the antisecretory effect is significantly longer when calcium, aluminum and magnesium sutures are used, which therefore, compared to the acid CR 501, has the advantage of improved therapeutic activity.

Table 2 shows that these calcium, aluminum and magnesium salts also exhibit a higher protective effect independent of their cation content (as up to 10 times the amount of cation supplied with the CR 501 salt was ineffective by itself) .-.

In relation to the other salts and the starting compound, the sodium salt is, as can be seen from table 3, more particularly effective as an antispasmodic agent and can therefore be recommended for use in cases of ulcers on the duodenum which are complicated by cramps. This effect is probably due to the fact that the sodium salt is more soluble in water and body fluids.

Therapeutic application

A - Oral forms

Oral forms are all those that can be produced technically, more specifically gelatin capsules and simple tablets produced by pressing the powder mixed with a pharmaceutically acceptable excipient.

The recommended dose in each tablet or capsule is in the range from 150 to 300 mg.

In these forms, the calcium salt in particular is recommended, as

according to normal durability tests, it shows perfect stability and no photosensitivity, which is partly present in other salts.

The smallest dosage that can be recommended of CR 501 salt is 450 mg daily in three separate administrations spread over the day, each of 150 mg. When necessary, however, the dosage can be doubled or tripled.

B - Parenteral forms

Ampoules with aqueous solution: These can be obtained with CR 501 sodium salt according to the following recipe:

Higher concentrations of up to twice as much are possible.

These ampoules can be used for intravenous or intramuscular administration in a quantity of 1-3 ampoules daily.

The ampoules may also contain a solution in water with the addition of a pharmaceutically acceptable solvent which is miscible with water.

In this way, highly concentrated injectable solutions of CR 501 sodium salt can be obtained. As an example without being intended to be limiting for the choice of the water-miscible solvent, the following composition can be suggested:

Due to the presence of solvent, these ampoules can only be used for intramuscular injection. It is advisable to prescribe up to 3 ampoules daily.

C ~ Suppositories

The described salts can be administered through the rectum in the form of suppositories. The recommended dosage is 150-300 mg CR 501 salt in conjunction with a pharmaceutically acceptable excipient or carrier. 1-3 suppositories daily spread over the day or night can be prescribed.

Endurance

The salts of CR 501, more specifically the sodium salt by parenteral administration and the calcium salt by oral administration, were examined with regard to acute and chronic toxicity in two animal species (rats and dogs), and no significant symptoms of toxicity, even with dosages (i.mg/ kg) of 20 times what is recommended for human therapy has been established. Teratogenesis tests in New Zealand rabbits showed no fetal toxicity.

In humans, long-term oral administration of CR 501 calcium salt over several weeks in doses of 500-1600 mg did not lead to any particular side effects. Administration via the endovenous and intramuscular route also did not cause disturbances.

Claims (5)

1. Process for the preparation of a DL- or L-tryptophan salt with the formula where X is Na, Ca, Al or Mg, n is 1,-2 or 3 corresponding to the valence of X and R is a p-chloro-benzoxy or p-chloro-phenyl group, characterized in that an aqueous solution of.DL - or L-tryptophan at a pHr value of over 7 as a result of the addition of sodium hydroxide or -carbonate is reacted with an essentially stoichiometric amount of p-chloro-benzoyl chloride or p-chloro-carbobenzoxy chloride dissolved in a organic solvent which is miscible with water, at a temperature of 14-18°C with stirring until a clear solution is obtained, and that the solvent is then extracted with the aid of another organic solvent which is mainly immiscible with water, after which either Na- the salt is precipitated from the remaining aqueous solution by adding propanol-2 or the remaining aqueous solution is reacted with a slight stoichiometric excess of a mineral salt of Ca, Mg or Al with stirring and the L-tryptophan salt is recovered as a precipitate. 2. Procedure as stated in crawl, characterized by that. the former organic solvent is tetrahydrofuran. 3. Method as stated in claim 1 or 2, characterized in that the said second organic solvent is ethyl acetate or isopropyl ether. 4. Method as stated in one of the preceding claims, characterized in that the mineral salt is Ca, Mg or Al chloride. 5. Method as stated in one of the preceding claims, characterized in that X is sodium or calcium.