GB2050363A - Esters of 2-(6-methoxy-2- naphthyl)-1-propanol, method of preparation and pharmaceutical compositions thereof - Google Patents

Abstract

Esters of 2-(6-methoxy-2-naphthy])-1-propanol of formula (I> <IMAGE> in which R is an alkyl radical of 1 to 20 carbon atoms are described. The compounds exhibit antiinflammatory, antirheumatic, analgesic and antipyretic activity.

Description

SPECIFICATION Esters of 2-(6-methoxy-2-naphthyl)-1 -propanol This invention relates to esters of a carboxylic acid and a 2-substituted propanol and specifically, propanol substituted by a 6-methoxy-2-naphthyl group of formula (I)

in which R is the alkyl residue of carboxylic acid containing between 1 and 20 carbon atoms.

It has been found that compounds offormula (I) exhibit very outstanding properties, specifically antiinflammatory, antirheumatic, analgesic and antipyretic properties comparable to the properties of a known substance, specifically Naproxen, which is the more active enantiomer of the 2-(6-methoxy-2natphthyl) propionic acid. Yet compared with Naproxen the compounds according to the presente invention are less toxic, exhibit an activity which is substantially more pronounced and cause much less noticeable gastric injury.

The object of the present invention is to provide compounds of formula (I). Another object of the present invention is to provide pharmaceutical compositions having antiinflammatory, anti rheumatic, analgesic and antipyretic activity which contain, as the active substance, at least one of the compounds of formula (I): Another object of the present invention, is to provide a process for the preparation of the compounds of formula (I) according to which 2-(6-methoxy-2-natphyl)-1-propanol (II) is reacted with a carboxylic acid of formula R-COOH in which R is as defined hereabove, in the presence of an acid catalyst.According to one embodiment of the invention, the preparation may be carried out from the same substituted alcohol with one active derivative of the same carboxylic acid according to the reaction scheme shown hereinbelow:

In the above reaction scheme, X is OH or an activating group, for instance a halogen atom or an alcoxycarboniloxy residue, for instance the group C2H5O-CO-O-.

The process according to the present invention is illustrated by the example hereinbelow.

EXAMPLE 1 2-(6-Methoxy-2-naphthyl)-propyl acetate a) 2-(6-Methoxy-2-naphthyl- 1-propanolJ In a three-neck flask provided with a mechanical stirrer, a condenser and a funnel, there are placed 300 ml of THF, 53.5 g of 2-(6-Methoxy-2-napthyl) propionaldehyde and 25 ml of water containing 2.5 g of NaOH.

Under stirring, 2 g of NaBH4 is slowly added keeping the temperature at 40"C. The mixture is stirred for one hour at room temperature and then there is added slowly under stirring and cooling, acetic acid for the purpose of destroying the excess of NaBH4. The greater part of the solvent is evaporated under vacuo, then water is added and the material is extracted three times with ether using a 100 ml portion each time. The ether extract is combined, evaporated under vacuo and the oily residue is crystallized from a mixture 50:50 of petroleum ether and ethyl ether.

The yield is 49.9 g (93.3%); M.P. 82-84"C.

b) 2-(6-Methoxy-2-naphthyl)propyl acetate In a three-neck flask provided with mechanical stirrer, condenser and a funnel, there are introduced 500 ml of ethyl ether, 58.9 g (0.725 mole) of pyridine and slowly under agitation 58.8 g (0.725 mole) of acetyl chloride.

The solution is cooled to 0 C and then there is introduced slowly through the funnel, 108 g (0.5 mole) of 2-(6-methoxy-2-naphthyl)propyl alcohol, dissolved in 200 ml of ethyl ether. The temperature rises up to about 40"C. Stirring is continued for a period of four hours at room temperature and then the solution is poured into 250 ml of water. The mixture is stirred and the organic phase is separated, washed with 0.1 N HCI solution. The organic phase so washed, is dried over anhydrous sodium sulfate. The solvent is evaporated under vacuo and the oily residue is distilled. The pure ester distills at 175 -178 C at a pressure of 0.01 mm Hg.

The yield is 102 g (75%).

According to the same procedure described hereinabove, the following substances are prepared: - 2-(6-methoxy-2-naphthyl)propyl propionate; Boiling Point-178-183 C at a pressure of 0.01 mm Hg.

- 2-(6-methoxy-2-naphthyl )propyl hexanoate Boiling Point-188-190 C at a pressure of 0.01 mm Hg.

EXAMPLE 2 Preparation of 2-66-methoxy-2-naphthylJpropyl enanthate In a three-neck flask provided with stirrer, condenser, and a funnel there are introduced 500 ml of ethyl ether, 58.9 g (0.725 mole) of pyridine and slowly under stirring 107.4 g (0.725 mole) of enanthyl chloride. The solution is cooled to 0 C. Through the funnel, there are introduced 108 g (0.5 mole) of 2-(6-methoxy-2naphthyl)propyl alcohol dissolved in 200 ml of ethyl ether. The temperature rises to 40 C. Stirring is continued for four hours at room temperature and then the solution is poured into 250 ml of water. The mixture is stirred, the organic phase is separated, washed with 0.1 N HCI solution. The organic phase so washed is dried over anhydrous sodium sulfate. The solvent is distilled under vacuo and the oily residue is distilled.The pure ester boils at 191-193"C at 0.01 mm Hg. The yield is 125.3 g (73,2%).

Ultraviolet light spectrum: a solution of the substance in ethanol (25 mcg/ml) exhibits two maxima: (1) at260 + 1 - 270 + 1 and (2) at316+1-331l1.

The substance is insoluble in water, soluble in chloroform, ethanol, acetone, hexane and in addition, in oils.

Application of the same procedure described hereinabove gives other esters of 2-(6-methoxy-2naphthyl)propanol as indicated in Table 1 hereinbelow, which also reports the physical properties and analytical values.

TABLE 1

R b.p. C/mm Hg ANALYSIS Calcd. Found Calcd. Found CH3 175-78/0.01 74.42 - 74.10 6.98 - 6.96 C2H5 178-83/0.01 75.00 - 74.84 7.35 - 7.31 C4H9 183-87/0.01 76.00 - 75.80 8.00 - 7.95 C5H11 188-89/0.01 76.43 - 76.20 8.28 - 8.31 C6H13 191-93/0.01 76.82 - 76.80 8.54 - 8.50 C7H15 193-95/0.01 77.19 - 77.00 8.77 - 8.80 C8H17 194-98/0.01 77.53 - 77.40 8.98 - 8.95 C9H19 198-200/0.01 77.84 - 77.81 9.19 - 9.10 C10H21 181-83/0.005 78.12 - 78.10 9.37 - 9.31 C11H23 185-87/0.005 78.39 - 78.43 9.55 - 9.56 C12H25 188-89/0.005 78.64 - 78.60 9.70 - 9.76 C14H29 191-93/0.005 79.00 - 79.00 10.00 - 10.20 C15H31 192-94/0.005 79.29 - 79.16 10.13 - 10.00 C16H33 195-97/0.005 79.50 - 79.61 10.26 - 10.15 C17H35 199-200/0.005 79.66 - 79.58 10.37 - 10.41 C18H37 201-202/0.005 79.84 - 79.77 10.48 - 10.44 The pharmaceutical properties of the compounds according to the present invention, together with toxicological data are reported by way of example with the compound 2-(6-methoxy-2-naphthyl)propyl enanthate referred to hereinafter with the symbol ENA.

Antiinflammatory activity This activity has been evaluated by comparison with Naproxen in equimolar dose. There are utilized male rats of average weight, about 150 g. Two tests, that is one acute and one sub-acute, have been carried out.

a) acute test: plantar edema caused by carragenin according to C.A. Winter et al. Proc. Soc. Exp. Biol.

Med., 111,544(1962).

The two substances under test are administered through the oral route in an equimolar dose: ENA = 60 mg/kg, Naproxen = 40 mg/kg, in 1% carboxymethylcellulose (CMC) at 20 ml/kg immediately after the appearance of the edema as a result of the subplantar injection of carragenin in the amount of 1% in the dose of 0.05 ml/paw. The results of this test are reported in Table 2.

b) sub-acute test: plantar edema caused by nystatin according to E. Arrigoni-Martelli et al, Pharmacolo gy, 5,215 (1971). The two substances are administered through the oral route in an equimolar dose for two successive days as follows: The first day, ENA = 30 mg/kg, Naproxen = 20 mg/kg in 1% CMC in the amount of 10 ml/kg.

The second day, ENA = 60 mg/kg, Naproxen = 40 mg/kg in 1% CMC in the amount of 20 mg/kg.

Edema has been caused the night preceding the first treatment by the subplantar injection of nystatin in the amount of 300,000 U/ml in the amount of 0.1 ml/paw. The results of this test are reported in Table 3.

TABLE 2 Antiinflammatory activity - acute test Each value is the average of 10 paws.

Treatment % Inhibition of Edema after: 2 hours 4 hours 6 hours 8 hours ENA 62 49 61 85 Naproxen 60 31 30 36 Statistical equal ENA more ENA more ENA more Comparison activity active active active P N.S. P < 0.025 P < 0.01 P < 0.05 As the data hereinabove show, ENA is as active as Naproxen in the second hour, but becomes more active in the subsequent hours, and after 8 hours still exhibits a very considerable activity.

TABLE 3 Antiinflammatory activity - sub-acute test Each value is the average of 10 paws.

DAY No.1 Treatment % Inhibition of Edema after: 1hour 2hours 4hours 8hours ENA 12 8 10 11 Naproxen 5 4 4 5 Comparison ENA more equal ENA more ENA more active activity active active P < 0.001 P N.S. P < 0.01 P < 0.01 DAY No. 2 Treatment % Inhibition of Edema after: 1 hour 2 hours 4 hours 8 hours ENA 6 12 12 17 Naproxen 5 8 7 11 Statistical equal equal equal ENA more Comparison activity activity activity active P N.S. P N.S. P N.S. P < 0.005 As it is clearly shown by the data, ENA exhibits a therapeutic activity towards a stable previously induced edema which is not only comparable to that of Naproxen, but particularly for very prolonged periods of time is greater and is statistically very significant.

Analgesic activity The analgesic activity has been determined by comparison with Naproxen in an equimolar dose. Two tests are carried out: one in female mice-of about 25 g average weight and one in male rats of about 100 g average weight.

a) test in the female mouse: contorsions due to phenylquinone according to L.C. Hendershot et al, J.

Pharm. Exp. Ther., 125,237 (1959).

The two compounds are administered through the oral route in essentially equimolar doses with respect to each other: ENA 30 mg/kg, naproxen 20 mg/kg in 1% CMC in the dose of 20 ml/kg. The contorsions are induced at different intervals after the administration of the compounds by endoperitoneal injection of 0.02% phenyquinone in 5% alcohol in the dose of 10 ml/kg.

The results of this test are reported in Table 4.

b) test in the male rat: this test is carried out by applying pressure on an inflamed paw according to L.O, Randall et al, Arch. Int. Pharmacodyn., 111,409 (1957).

The two compounds are administered through the oral route in doses which are equimolar with respect to each other: ENA 60 mg/kg, naproxen 40 mg/kg in 1% CMC in the dose of 20 ml/kg immediately after the inducement of the inflammation: sub-planar injection of 10% yeast in the amount of 0.1 ml/paw.

The results of this test are reported in Table 5.

TABLE 4 Analgesic activity - test in the mouse Each figure is the average of eight mice.

Treatment % Inhibition of contorsions after: 1 hour 2hours 4hours 6hours ENA 27 57 44 46 Naproxen 14 68 30 13 Statistical equal equal equal ENA more Comparison activity activity activity active P N.S. P N.S. P N.S. P < 0.01 As the data hereinabove show, ENA exhibits an activity comparable to that of Naproxen in the first few hours, but the activity is maintained still high in the sixth hour while with Naproxen, the activity is substantially reduced.

TABLE 5 Analgesic activity - test in the rat Each figure is the average of 10 paws.

Treatment % Inhibition of pain after: 1 hour 2 hours 3 hours 4 hours 5 hours ENA 240 400 . 152 131 100 Naproxen 47 79 67 64 64 Statistical ENA more ENA more equal equal equal Comparison active active activity activity activity P < 0.001 P < 0.001 P N.S. P N.S. P N.S.

As the data shows, in this test ENA exhibits greater analgesic activity than Naproxen in a significant manner in the first few hours. After the first few hours, greater activity is apparent, but not statistically significant.

Antip yretic activity This activity has been determined by comparison with Naproxen in equimolar doses. Two animal species have been utilized. Male rats of weight about 250 g and female rabbits of about 2.6 kg of weight.

a) the test in the rat: pyrexia caused by yeast according to U.M. Teotino et al, J. Med. Chem., 6, 248 (1963).

The two compounds are administered through the oral route in doses which are equimolar with respect to each other: ENA 60 mg/kg, Naproxen 40 mg/kg in 1% CMC, in the dose of 10 ml/kg. The fever has been induced the previous night by subcutaneous injection of a 20% yeast suspension in the dose of 10 ml/kg. The results are reported in Table 6.

b) the test in the rabbit: pyrexia caused by yeast.

The two compounds are administered in the oral route by equimolar doses: ENA 60 mg/kg, Naproxen 40 mg/kg in 1% CMC in the dose of 10 ml/kg immediately after the first inducement of fever by means of 20% yeast suspension, which is centrifuged, filtered and the filtrate injected endovenously in the dose of 1 ml/kg.

This treatment to cause fever has been repeated twice at intervals of one hour and 30 minutes. The results are reported in Table 7.

TABLE 6 Antipyretic activity - test in the rat Each data is the average of 5 animals.

Treatment Reduction of fever in "C after: 1hour 2 hours 4 hours 8 hours ENA 0.80 1.22 1.32 1.00 Naproxen 0.76 1.24 1.32 0.94 Statistical equal equal equal equal Comparison activity activity activity activity P N.S P N.S. P N.S. P N.S.

In this test, the activity of the two substances is about parallel and both of them retain high activity in the eighth hour.

TABLE 7 Antipyretic activity - test in the rabbit Each data is the average of 4 animals.

Treatment Reduction of fever in "C after: 2 hours 4 hours 6 hours 8 hours ENA 0.59 0.58 0.48 0.51 Naproxen 1.04 0.61 0.28 0.25 Statistical ENA less equal ' ENA more ENA more Comparison active activity active active P < 0.05 P N.S. P < 0.05 P < 0.05 In this test, the antipyretic activity of ENA is at first lower than that of Naproxen, and then it is equal, and then in the sixth and eighth hours remains constant while the activity of Naproxen becomes inferior in a statistically significant manner.

Acute toxicity The acute toxicity of ENA has been determined on two species of animals: mice of both sexes of average weight about 20 g and rats of both sexes of average weight about 200 g.

Four routes of administration have been used: oral, endoperitoneal, endovenous and subcutaneous. In each instance, the animals were deprived of food the night before the test. There are utilized ten animals, that is five males and five female per each dose of treatment. The values of DL 50, expressed in ml/kg, are calculated according to the method of probits on the basis of the mortality found within a period of eight days of the treatment.

The results are reported in Table 8. They show the comparison of DL 50 of ENA with the DL 50 of Naproxen, which comparison is partly based upon literature data and partly upon original experimental work.

TABLE 8 Acute toxicity - DL 50 in mglkg Species Route DL 50 Equivalent DL 50 Ratio ENA to Naproxen Naproxen Naproxen/ENA Mouse oral 4200 2800 1234* 0.44 i.p. 5000 3333 550 0.17 i.v. 1000 667 435* 0.65 s.c. > 9000 > 6000 1100 < 0.18 Rat oral 3200 2133 543* 0.25 i.p. 3330 2222 575* 0.26 i.v. 1000 667 400 0.60 s.c. > 3000 > 2000 1000 < 0.50 (*) A.P. Roszkowski et al, J. Pharm. Exp. Ther., 179, 114(1971).

As shown in the ratios in the last column of the above table, ENA is much less toxic, about 1/2 to 1/5 as compared to Naproxen, keeping also in mind the different molecular weight.

Toxicity in the fetus This type of toxicity has been investigated in two animals species, rats and rabbits.

a) the test in the rat: ten female rats have been treated in the first 20 days of gestation through the oral route with ENA in the dose of 20 ml/kg/day, equal to 13.2 mg/kg of Naproxen. Afterwards, the animals have been sacrificed in order to remove the fetuses and to observe the uterus. The properties which have been observed are: the growth of the mother, the number of live fetuses, the number of dead fetuses, average weight of the litter, number of reabsorptions and malformations.

Results: no toxic symptons on the gestation and on the fetuses has been observed.

b) the test in the rabbit: five female rabbits have been treated in the first 24 days of gestation through the oral route with ENA in the dose of 20 mg/kg/day, equal to13.2 mg/kg of Naproxen. Afterwards the animals have been sacrificed in order to remove the fetuses and to observe the uterus. The properties which have been observed have been: the growth of the mother, the number of live fetuses, the number of dead fetuses, the average weight of the litter, the number of reabsorptions and malformations.

Results: no toxic symptons have been observed either on the gestation or on the fetuses.

Sub-acute toxicity through the rectal route Six rabbits, that is three male and three female rabbits of average weight about 2 kg have been treated.

The daily treatment for a period of ten days consisted of suppositories containing 300 mg of active material which was introduced deep down in the rectal orifice while the orifice was kept closed for a period of 30 minutes with cocher clamps. This treatment has not shown significant variation of the general state of health, the body weight, hematic crasis, lever function, glycemia, azotemia, glycosuria, proteinuria, ematuria.

Sub-acute toxicity through the oral route (ulcerogenesis) The comparison has been carried out by using an amount of ENA which is equimolar to that dose of Naproxen which is known to be ulcerogenic. Male rats of 150 g about average weight, have been used, being kept partially fasting (only at night) in a total number of five. The daily treatment has been carried out by introducing into the esophagus: ENA in the amount of 150 mg/kg/day, Naproxen 100 mg/kg/day in 1% CMC in the dose of 5 mg/kg. A few hours after the fifth administration, one animal died between the treatments with Naproxen and it was decided to sacrifice all the animals to observe them. The results of the observations made during the five-day period and of the death are reported schematically in Table 9.

TABLE 9 Ulcerogenic gastro-enteric effect in rats ENA Naproxen Observations prior to death Animals Animals n - /O n -% Significant paleness 0 0 2 40 Weight reduction 15% beginning onOday 0 0 3 60 Lack of growth between the 4th and 5th day 0 0 4 80 Blood in the fetus 0 0 2 40 Diarrhea 0 0 2 40 Death (due to peritonitis) 0 0 1 20 Observations after death Lack offeeding 0 0 2 40 Anemicdigestivetube 0 0 5 100 Gastro-intestinal ulcer 0 0 1 20 As it appears from the data hereinabove, the daily dose of Naproxen which has been used is very toxic up to the point of being lethal through the gastro-enteric route, while the equimolar dose of ENA gives no symptoms of intolerability nor symptoms of gastro-entero injury even after five days.

EXAMPLE 3 Capsules of soft gelatin : every capsule contains: 2-(6-methoxy-2-naphthyl)propyl enanthate 350 mg EXAMPLE 4 Suppositories: each suppository contains: 2-(6-methoxy-2-naphthyl)propyl enanthate 300 mg Miglyol 50 mg Witepsol E 85 460 mg Witepsol W 35 to 2.2 9 EXAMPLE 5 Suppositories:each suppository contains: 2-(6-methoxy-2-naphthyl)propyl enanthate 600 mg Miglyol 10 mg Witepsol E 85 370 mg Witepsol W 35 to 2.3 9 EXAMPLE 6 5% Cream: 100 g of cream contain: 2-(6-methoxy-2-naphthyl)propyl enanth ate 5g Cetylstearyl alcohol 5 g Isopropyl myristate 7g Oil of vaseline 5g Spermacetes 7g Stearic acid 2g Polysorbitan monolaurate 60 0.5g Carboxyvinyl polymer with triethanolamine lg Benzoic acid 2 g Distilled water 100 g EXAMPLE 7 Phthials of300 mg: each 2 ml phthial contains: 2-(6-methoxy-2-naphthyl)propyl enanthate 300 mg Lidocain base 10 mg Benzyl Alcohol 50 mg Ethyl oleate (or olive oil Fu) to 3 ml.

This composition of the present invention may be used to relieve a living subject from inflammation, pain, fever in the dose of 300-1200 mg/day.

Claims (5)

1. An ester of 2-(6-methoxy-2-naphthyl)propanol of formula (I)

wherein R is an alkyl radical of 1 to 20 carbon atoms.

2. A compound according to claim 1 which is 2-(6-methoxy-2-naphthyl)propyl enanthate.

3. A pharmaceutical composition having antiinflammatory, antirheumatic, analgesic, and antipyretic activity which comprises as the active ingredient at least one compound according to claim 1.

4. A pharmaceutical composition according to claim 3 wherein the active compound is 2-(6-methoxy-2naphthyl)propyl enanthate.

5. The process for the preparation of an ester of 2-(6-methoxy-2-naphthyl)propanol of formula (I) which consists of reacting 2-(6-methoxy-2-naphthyl)propanol of formula (II) with a compound of formula (III) according to the equation hereinbelow:

wherein R is an alkyl radical between 1 and 20 carbon atoms, X is OH or halogen or an alcoxy-carbonyloxy radical and isolating said compound of formula (I) from the reaction mixture.