ANTHRANILIC ACID ESTER DERIVATIVES AND ANTI-INFLAMMATORY AND ANALGESIC EXTERNAL PREPARATIONS CONTAINING THE SAME

Abstract: Anthranilic acid ester derivatives having the general formula (I): wherein R represents an alkyl group having 1 to 3 carbon atoms substituted with a pyridyl group or a furanmethyl group. These anthranilic acid ester derivatives have remarkable anti-inflammatory and analgesic effects and a high endermic permeability and are therefore suitable for use as anti-­ inflammatory and analgesic agents.

Description: Backgroung of the Invention Field of the invention The present invention relates to novel anthranilic acid ester deriva­ tives having the general formula (I): wherein R represents an alkyl group having 1 to 3 carbon atoms substituted with pyridyl group or a furanmethyl group and external preparations containing the same having remarkable anti-inflammatory and analgesic effects. Description of the related art The anthranilic acid ester derivatives having the general formula (I) are novel compounds not reported in any publication at this time. N-(2,3-xylyl)anthranilic acid, a mother compound of the anthranilic acid ester derivatives according to the present invention, is generally called mefenamic acid, and is widely used as an anti-inflammatory, anti-­ rheumatic, antipyretic and analgesic agent. However, it is very difficult to dissolve N-(2,3-xylyl)anthranilic acid in, for example, water, alcohol, or oil and, therefore, it is used solely as an oral agent or drug in the form of a powder or in the dosage form of a table or capsule. Thus, heretofore N-(2,3-xylyl)anthranilic acid has not been used as a skin treatment agent or as a topically or percutaneously applicable drug. Furthermore, it is known that when N-(2,3-xylyl)anthranilic acid is orally administered, various side effects including enterogasteric disorders, renal disorders and vertigo occur. Summary of the invention Accordingly, the objects of the present invention are to eliminate the above-mentioned disadvantages and to provide a novel N-(2,3-xylyl)an­ thranilic acid ester derivative having improved safety, endermic permeabi­ lity, affinity to the skin, and a remarkable anti-inflammatory and analgesic activity. Another object of the present invention is to provide anti-inflamma­ tory and analgesic external preparations having remarkable anti-inflamma­ tory and analgesic effects suitable for topical application to the skin. Other objects and advantages of the present invention will become apparent from the following description. In accordance with the present invention, there is provided anthra­ nilic acid ester derivatives having the above-mentioned general formula (I). Description of the preferred embodiments The novel N-(2,3-xylyl)anthranilic acid ester derivatives having the general formula (I) according to the present invention are soluble in organic solvents, for example, hydrocarbons such as hexane and benzene, alcohols such as ethyl alcohol and propyl alcohol, and ketones such as acetone and methyl ethyl ketone. The novel pyridylalkyl -N-(2,3-xylyl)anthranilates having the general formula (I), in which R represents an alkyl group having 1 to 3 carbon atoms substituted with a pyridyl group, are in the form of pale yellow crystals. On the other hand, the novel 2-furanmethyl-N-(2,3-xylyl)anthra­ nilates having the general formula (I) in which R represents a furanyl­ methyl group are in the form of white crystals. The N-(2,3-xylyl)anthranilic acid ester derivatives having the general formula (I) can be prepared by any conventional acid esterification reaction method. For example, the N-(2,3-xylyl)anthranilic acid ester derivatives (I) can be prepared by reacting N-(2,3-xylyl)anthranilic acid or the halides thereof with a pyridylalkyl alcohol or furfuryl alcohol, or by reacting the alkali salts of N-(2,3-xylyl)anthranilic acid with the halides of pyridylalkyl alcohol or 2-methyl halides of furan. The alkyl moieties of the pyridylalkyl groups include methyl, ethyl, n-propyl, and iso-propyl moieties, preferably methyl and ethyl moieties, since the desired anti-inflammatory activity tends to decrease with the increase in the carbon number of the alkyl moiety. The N-(2,3-xylyl)anthranilic acid ester derivatives having the general formula (I) include: 2-pyridylmethyl-N-(2,3-xylyl)anthranilate; 3-pyridylmethyl-N-(2,3-xylyl)anthranilate; 4-pyridylmethyl-N-(2,3-xylyl)anthranilate; 2-(2-pyridyl)ethyl-N-(2,3-xylyl)anthranilate; 2-(3-pyridyl)ethyl-N-(2,3-xylyl)anthranilate; 2-(4-pyridyl)ethyl-N-(2,3-xylyl)anthranilate; 2-(2-pyridyl)propyl-N-(2,3-xylyl)anthranilate; 2-(3-pyridyl)propyl-N-(2,3-xylyl)anthranilate; 2-(4-pyridyl)propyl-N-(2,3-xylyl)anthranilate; 3-(2-pyridyl)propyl-N-(2,3-xylyl)anthranilate; 3-(3-pyridyl)propyl-N-(2,3-xylyl)anthranilate; 3-(4-pyridyl)propyl-N-(2,3-xylyl)anthranilate; 2-(furanmethyl-N-(2,3-xylyl)anthranilate; The novel N-(2,3-xylyl)anthranilic acid ester derivatives having the general formula (I) according to the present invention can be either administered or applied orally or parenterally. Therefore, the present compounds can be in the form of, for example, tablets, capsules, powder, granules and syrup in the case of oral administration, a suppository in the case of rectal administration, and ointments, cream, dermatological paste, cataplasm, liquid, aerosol, and gel, in the case of external skin applications. Furthermore, since the novel N-(2,3-xylyl)anthranilic acid ester derivatives according to the present invention are readily soluble in organic solvents, for example, alcohols such as ethyl alcohol and propyl alcohol, and ketones such as acetone and methyl ethyl ketone, and are highly compatible with cream bases such as polyols, liquid paraffins, and ester oils as well as ointment bases such as petrolatum and lanolin, the present compounds can be advantageously formulated into externally applica­ ble skin treatment compositions. This is also preferable because the present compounds have an excellen endermic permeability. When the present compounds are topically applied to the skin as a skin treatment composi­ tion, a remarkable anti-inflammatory effect is exhibited and an excellent analgesic quality is also exhibited against concomitant pain. Thus, the N-(2,3-xylyl)anthranilic acid ester derivatives according to the present invention are remarkably effective for use against acute eczema, chromic aczema, atopic dermatitis, contact-type dermatitis, zoster, various ecze­ matoid dermatitis, various wounds, acne vulgaris, ambustion, acute and chronic arthritis, periarthritis, lumbago and sarcitis. Although the administered or applied quantity of the anti-inflam­ matory and analgesic agent according to the present invention can be widely varied depending upon, for example, ages, individuals, and disease condi­ tions, it is preferably 1 to 400 mg/kg/day in the case of oral adminis­ tration and, preferably 0.01 to 100 mg/kg/day, and more preferably 0.1 to 10 mg/kg/day, in the case of topical application. In either case, the agent can be administered or applied once or several times a day. Examples The present invention will now be further illustrated by, but is by no means limited to, the following examples. Synthetic example 1 2.36 g of sodium N-(2,3-xylyl)anthranilate was dissolved in 20 ml of dimethyl formamide and 1.25 g of 2-chloromethyl pyridine was then added thereto. The mixture was allowed to react at a temperature of 90°C for 3 hours. After the reaction, the solvent was distilled off in vacuo and water was added to the residue. The mixture was then extracted with ether. After dehydration, the ether was distilled off and the resultant residue was recrystallized from methanol. Thus, 3.00 g of the desired pale yellow 2-pyridylmethyl- N-(2,3-xylyl)anthranilate having the following physical properties was obtained. m.p.: 63-64°C Elemental analysis: C₂₁H₂₀O₂N₂ Mass spectrum parent ion (m/e) - 332. Synthetic example 2 2.41 g of N-(2,3-xylyl)anthranilic acid and 3.6 g of thionyl chloride were mixed in 20 ml of benzene and the mixture was reacted under reflux for 3 hours. The solvent and the extra thionyl chloride were distilled off. The residue was then added to 50 ml of tetrahydrofuran and 1.37 g of 3-(4-pyridyl)propanol, followed by a gradual addition of 1.5 g of triethyl­ amine while stirring at room temperature. The mixture was stirred for 30 minutes and then allowed to react under reflux for one hour. After the reaction, the solvent was distilled off in vacuo and water was added to the residue. The mixture was then extracted with ether. The oily residue thus obtained was recrystallized from methanol, and the desired pale yellow 3-(4-pyridyl)propyl-N-(2,3-xylyl)anthranilate having the following physical properties was obtained. m.p.: 56-57°C Elemental analysis: C₂₂H₂₄O₂N₂ Mass spectrum parent ion (m/e) = 360. Synthetic examples 3 to 6 The following compounds listed in Table 1 were prepared in the same manner as in Synthetic Examples 1 and 2. Synthetic example 7 25.3 g of sodium N-(2,3-xylyl)anthranilate was dissolved in 200 ml of dimethylformaldehyde and 11.7 g of 2-chloromethyl furan was then added. The mixture was allowed to react at a temperature of 90°C for 3 hours. After the reaction, the solvent was distilled off in vacuo, water was added to the residue and the mixture was then extracted with diethyl ether. After dehydration, the ether was distilled off and the resultant residue was recrystallized from ethanol. Thus, 28.3 g of white crystalline 2-furanmethyl-N-(2,3-xylyl)anthranilate having the following physical properties was obtained. m.p.: 50-51°C Elemental analysis: C₂₀H₁₉NO₃ Mass spectrum parent ion (m/e) = 321. Synthetic example 8 24.1 g of N-(2,3-xylyl)anthranilic acid was dissoved in 220 ml de dichloromethane and 22.7 g of N,N'-dicyclohexylcarbodiimide was added. The mixture was stirred for 30 minutes and 1.48 g of 4-pyrrolidinopyridine and 10.8 g of furfuryl alcohol were then added thereto. The mixture was stirred at room temperature for 5 hours. After the reaction, the mixture was filtered and the solvent of filtrate was evaporated in vacuo. The residue was recrystallized from ethanol. Thus, 28.2 g of the desired white crystalline 2-furanmethyl-N-­ (2,3-xylyl)anthranilate having the following physical properties was obtained. m.p.: 50-51°C Mass spectrum parent ion (m/e) = 321. Evaluation test results The N-(2,3-xylyl)anthranilic acid ester derivatives were evaluated with respect to the toxicity and pharmacological activities thereof. Evaluation test example 1 (acute toxicity) The evaluation test was carried out using ddY male mice (i.e., body weight: 18 to 22 g, 10 mice in each group). The sample compound listed in Table 2 was dispersed in 0.5% carboxy­ methyl cellulose/physiological saline solution and orally administered in a given quantity by a peroral syringe. After the administration, the toxic conditions were observed and the oral acute toxicity (LD₅₀) was calculated from the number of deaths during 7 days of observation according to the Litchfild Wilcoxon method. The results are shown in Table 2, in which the compounds are shown by R in the general formula (I). The compount represented by R = H in Table 2 is a known reference compound i.e., N-(2,3-xylyl)anthranilic acid. As is clear from the results shown in Table 2, the LD₅₀ of the compounds according to the present invention is about three times higher than that of the known N-(2,3-xylyl)anthranilic acid. Thus the toxicity of the present compounds is very low. Evaluation test example 2 (Acute toxicity) The evaluation test was carried out using ICR female mice (i.e., body weight = 18 to 22 g, 10 mice in each group). The sample compounds listed in Table 3 were dispersed in 2.0% carboxy­ methyl cellulose/physiological saline solution and orally administered in a given quantity by a peroral syringe. After the administration, the toxic conditions were observed and the oral acute toxicity (LD₅₀) was calculated from the number of deaths according to the Van Der Werden method. The results are shown in Table 3. As is clear from the results shown in Table 3, the LD₅₀ of the present compound, i.e., 2-furanmethyl-N-(2,3-xylyl)anthranilate , is about 4 times higher than that of the known N-(2,3-xylyl)anthranilic acid. Thus, the toxicity of the present invention compound is very low. Evaluation test example 3 (anti-inflammatory activity) The anti-inflammatory effects of the present compounds were determin­ ed according to the so-called rat/carrageenan foot pad oedema method. This method is admitted as a standard test method for determining anti-inflamma­ tory effects, since it has a high correlationship with human anti-inflam­ matory effects. The evaluation test was carried out using Wister male rats (i.e., body weight : 100 - 130 g, 8 rats in each group) according to the Winter et al method set forth in "Proceedings of the Society for Experimental Biology & Medicine, 111 , p. 554, 1962). The sample compounds listed in Table 4 were dispersed in a 0.5% aqueous carboxymethyl cellulose solution and orally administered in a dosage of 100 mg/kg. One hour after the administration, 0.1 ml of a 1% λ-carrageenan/physiological saline was subcutaneously applied to the foot pad of one paw of the rat as an inflammatory inducing substance. Thus, the oedema was provoked. The volumes of the foot pad were measured in the predetermined constant time period before and after the administration and the increase (V₁) in the volume was calculated. On the other hand, the increase (V₀) in the volume of the foot pad of the control rats, to which the aqueous 0.5% carboxymethyl cellulose solution containing no test sample compounds was previously added, was determined by injecting the λ-carra­ geenan. Thus, the inhibition (%) of the carrageenan oedema was calculated as follows: The anti-inflammatory activity is high when this value is great. The results obtained 5 hours after the λ-carrageenan injection are shown in Table 4. As is clear from the results shown in Table 4, the oedema inhibitory activities of the N-(2,3-xylyl)anthranilatic acid ester derivates according to the present invention are as strong as for the known N-(2,3-xylyl)anthra­ nilic acid (i.e., R = H in the general formula (I)). Evaluation test example 4 (Anti-inflammatory activity) The evaluation test of 2-furanmethyl- N-(2,3-xylyl)anthranilate was carried out in the same manner as in Evaluation test example 3. The results are shown in Table 5. As is clear from the results shown in Table 5, the oedema inhibitory activity of the present compound, i.e. 2-furanmethyl- N-(2,3-xylyl)anthra­ nilate, is as stropng as for the known N-(2,3-xylyl)anthranilic acid. Evaluation test example 5 (Anti-inflammatory activity) The evaluation test of N-(2,3-xylyl)anthranilic acid derivatives was carried out according to the so-called ultraviolet erythema method. Healthy Hartley strain albino guinea pigs (i.e., body weight = 450 -­ 500 g, 10 guinea pigs in each group) were used as the test animals. The back skin of the guinea pigs was clipped and shaved, and sections having a size of 1.41 cm × 1.41 cm were prepared in the back skin, by using a rubber plate, symmetrically spaced from the back center line. The divided sections were irradiated with ultraviolet ray having a medium wavelength (i.e., 280 - 320 nm, λ max - 305 nm) to induce erythema. After the UV irradiation, 10 µl of a solution of the test sample compound in olive oil was applied to the sections on one side. The formation of the erythema was observed over a period of time. The average erythema (E₁) in the section to which the sample compound was applied and the average erythema (E₀) in the section to which no sample compounds were applied were measured. From these results, the inhibition (%) of the UV induced erythema was calculated from the following equation: When the inhibitory value (%) is great, the anti-inflammatory activ­ ity of the sample compound is high. The results obtained 3 hours after the time of the UV irradiation are shown in Table 6. As is clear from the results shown in Table 6, the novel N-(2,3-­ xylyl)anthranilic acid derivatives according to the present invention have anti-inflammatory activities similar to or stronger than those of the known N-(2,3-xylyl)anthranilic acid. Evaluation test example 6 (Anti-inflammatory activity) The anti-inflammatory activity test of the 2-furanmethyl-N-(2,3-xylyl)an­ thanilate was carried out in the same manner as in Evaluation test exam­ ple 5. The results are shown in Table 7. As is clear from the results shown in Table 7, the 2-furanmethyl- N-­ (2,3-xylyl)anthranilate according to the present invention leads to an erythema stronger than that of the known N-(2,3-xylyl)anthranilic acid. Evaluation test example 7 (Analgesic activity) The analgesic activity of the N-(2,3-xylyl)anthranilic acid deriva­ tives according to the present invention was carried out by the so-called Randall-Selitto method set forth in Randall, L.O. and Selitto, J.J., "Archives of International Pharmacodynamics, 111 , p.409 (1957). This method is admitted as a standard method for evaluating non-anesthetic analgesic agent. The test sample compounds were applied to both foot pads of the hind paws of the rats each in an applied or administered quantity of 50 µl as a 2.5% ethanol solution. After one hour, 50 µl each of the ethanol solution of the sample compound was again applied and 0.1 ml of a 5% brewer's yeast/physiological saline solution was immediately subcutaneously applied to one foot pad of the rat as a pain inducing substance. After a predeter­ mined time period, the weight of the pain generation was measured using a horizontal balance type presser and the decrease rate (P₁) of the pain threshold value was determined. The above-mentioned evaluation test proce­ dure was also carried out in the control rat group, except that the solvent containing no sample compounds was applied. Thus, the decrease rate (P₀) of the pain threshold value in the control group was determined. The inhibition (%) of the pain induced by the brewer's yeast was calculated as follows: When this value is great, the analgesic activity is high. The results obtained 5 hours after the time of the injection of the brewer's yeast are shown in Table 8. As is clear from the results shown in Table 8, the N-(2,3-xylyl)an­ thranilic acid ester derivatives according to the present invention exhib­ ited excellent analgesic activities higher than those of the two reference compounds. Thus, the present compounds are clearly effective as an anal­ gesic agent. As is clear from the results shown in the above-mentioned Evaluation test examples, the N-(2,3-xylyl)anthranilic acid ester derivatives accord­ ing to the present invention can be safely used as anti-inflammatory and analgesic agents. Formulation example 1 (ointment) The ingredient (1) was mixed in the ingredient (2), followed by degassing in vacuo. Thus, the ointment was formulated. Formulation example 2 (ointment) The ingredient (1) was mixed with the ingredient (2), followed by degassing in vacuo. Thus, the ointment was formulated. Formulation example 3 (cream) A mixture of the ingredients (1) to (6) was dissolved under heating and the mixture having a temperature of 70°C was added to the ingredients (7) to (9), at a temperature of 70°C, while stirring. The resultant mixture was treated in a homomixer to form fine emulsified particles and was then quenched while stirring. Thus, the desired cream was formulated. Formulation example 4 (lotion) The ingredients (2), (3), (7), and (8) were dissolved in the ingredient (9). On the other hand, the ingredients (1), (5), and (6) were dissolved in the ingredient (4) and the resultant solution was added to the above aqueous solution to be solubilized. After filtra­ tion, the desired lotion was obtained. Formulation example 5 (Dermatologic paste) A portion of the ingredient on a water bath (4) was dissolved and was then charged with the ingredient (1). Thereafter, the resul­ tant mixture was mixed with the ingredients (2) and (3), which were previously sifted through a 200 mesh sieve. After adding the remaining ingredient (4), the mixture was thoroughly mixed to obtain a uniform mizture. Thus, the desired dermatological paste was formulated. Formulation example 6 (Emulsion) The ingredient (7) and (8) were added to the ingredient (9), and the mixture (i.e. aqueouse phase) was maintained at a temperature of 70°C. On the other hand, the remaining ingredients were mixed and were dissolved upon heating. The resultant oil phase was also main­ tained at a temperature of 70°C. The oil phase was added to the aqueous phase and, after preemulsify­ ing, the mixture was uniformly emulsified in a homomixer. After the emulsi­ fication, the emulsion was cooled to a temperature of 30°C. Thus, the desired emulsion was obtained. The antiphlogistic and analgesic skin treatment compositions prepared in Formulation examples 1 to 6 were stable with the lapse of time and exhibited excellent anti-inflammatory and analgesic activities when the compositions were applied to the affected portions directly or via suitable fabrics, such as a gauze, having the compositions coated thereon.

Claims: 1.-Anthranilic acid ester derivatives having the general for­ mula (I): wherein R represents an alkyl group having 1 to 3 carbon atoms substituted with a pyridyl group or a furanmethyl group. 2. - Anthranilic acid ester derivatives as claimed in claim 1, wherein R in the formula (I) is an alkyl group having 1 to 3 carbon atoms substi­ tuted with a pyridyl group. 3. - Anthranilic acid ester derivatives as claimed in claim 1, wherein R in the formula (I) is a furanmethyl group. 4. - Anti-inflammatory and analgesic external preparations comprising, as an active component, an anthranilic acid ester derivative having the general formula (I): wherein R represents an alkyl group having 1 to 3 carbon atoms substituted with a pyridyl group or a furanmethyl group.

Inventors: HIRAO, TETSUJI SHISEIDO LABORATORIES, MAGARA, TSUNAO SHISEIDO LABORATORIES, SATO, YOSHIHISA SHISEIDO LABORATORIES, SHIRATORI, KOHYA SHISEIDO LABORATORIES
Applicants: SHISEIDO COMPANY LIMITED
Application year: 1986
Main classification: C07D213
IPC codes: C07D307, C07D213