Novel parabanic acid derivatives as aldose reductase inhibitors

Abstract: A compound is provided represented by the following general formula (I) In the formula, R is hydrogen, C₁₋₄ alkyl or benzyl; X is phenyl which is substituted with trifluoromethyl, cyano, carboxy, carbamoyl, C₁₋₃ alkoxycarbonyl or both nitro and halogen, benzothiazolyl which may be substituted with C₁₋₃ alkyl, C₁₋₃ alkoxy, trifluoromethyl, nitro and/or halogen, naphthyl which may be substituted with nitro and/or halogen, pyridyl which may be substituted with nitro and/or halogen, anthraquinonyl, phthalimide, or thienyl; and n is an integer from 1 to 3. The compounds act as selective inhibitors of aldose reductase. The compounds provided are useful as drugs for therapy and prevention of various types of diabetic complications.

Description: The present invention relates to novel parabanic acid derivatives and pharmaceutically acceptable salts thereof and also to a pharmaceutical composition containing said compounds as the effective component. Diabetic neuropathy, diabetic cataract and retinopathy, diabetic nephropathy, diabetic dermopathy and other diabetic microangiopathy have been known as difficulty treatable chronic diseases as a result of diabetes. Participation of a polyol metabolic system may be given as a cause of those diabetic complications. Thus, when a hyperglycemic state is resulted due to diabetes, utilization of glucose via a polyol metabolic pathway becomes several times as much as compared with the normal state and production of sorbitol by an aldose reductase is accelerated. It is presumed that, as a result thereof, intracellular sorbitol in peripheral nerves, retina, kidney, lens, artery and the like is accumulated excessively and it leads to cell edema and hypofunction due to an abnormal osmotic pressure in the cells. Accordingly, agents for inhibiting an aldose reductase have been thought to be effective for the therapy and the prevention of diabetic complications and have been studied. However, conventional aldose reductase inhibitors have a problem that they strongly inhibit other enzymes which do not participate in the polyol metabolic pathway such as an aldehyde reductase too. EP 0 353 198 A discloses parabanic acid derivatives which have aldose reductase inhibitory activity. The compounds are substituted in the 3-position of the molecule by hydrogen, an alkyl group, a cycloalkyl group, a lower alkylcycloalkyl group, a phenyl group or a phenylalkyl group which may optionally be substituted. Under such circumstances, the present inventors have conducted a study on inhibitors having a high enzyme selectivity to the aldose reductase participating in the sorbitol production with an object of therapy and prevention of the above-mentioned diabetic complications. As a result, the present inventors have found that the parabanic acid derivatives of the present invention exhibit an excellent inhibitory action with a high enzyme selectivity to aldose reductase whereby the present invention has been achieved. An object of the present invention is to offer novel parabanic acid derivatives and pharmaceutically acceptable salts thereof having an excellent inhibitory action to aldose reductase with a high enzyme selectivity and also to offer a therapeutic agent for diabetic complications containing said compounds as an effective component. The parabanic acid derivative of the present invention is a compound which is represented by the following general formula (I). wherein: R is hydrogen, C 1-4 alkyl or benzyl; X is benzothiazolyl which may be substituted with C 1-3 alkyl, C 1-3 alkoxy, trifluoromethyl, nitro and/or halogen, naphthyl which may be substituted with nitro and/or halogen, anthraquinonyl, or phthalimide. The parabanic acid derivatives of the present invention may be, for example, prepared in accordance with the following method. Thus, in a suitable solvent which does not disturb the reaction such as ethanol, acetone and N,N-dimetylformamide and in the presence of an alkali such as potssium hydroxide, potassium bicarbonate and sodium hydride, a compound of the general formula (II) Wherein, R is hydrogen, lower alkyl or benzyl; is subjected to a condensation reaction with a compound represented by the general formula (III) X-CH 2 -R 1 wherein X is as defined previously followed, if necessary, by subjecting to a hydrolysis, whereupon a parabanic acid derivative represented by the general formula (I) is prepared. The reaction may be carried out at room temperature or by heating to reflux depending upon the type of the alkali and others used there. In the case of the compound represented by the general formula (II) in which R is lower alkyl or benzyl, a conventional hydrolysis with an acid such as a dissolution in a mixture of acetic acid and concentrated hydrochloric acid followed by heating to reflux is carried out after completion of the above-mentioned condensation whereupon the compound represented by the general formula (I) in which R is hydrogen can be prepared. A side reaction hardly takes place when the compound of the general formula (II) in which R is lower alkyl is used whereby more preferred manufacturing method can be provided. In the above-mentioned general formulae (I) and (II), R is hydrogen; a linear or branched alkyl having 1 to 4 carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl and tert-butyl; or benzyl. In the above-mentioned general formulae (I) and (III), X is benzothiazolyl which may be substituted with a linear or branched alkyl having 1 to 3 carbon atoms such a methyl, ethyl, propyl and isopropyl, a linear or branched alkoxy having 1 to 3 carbon atoms such as methoxy, ethoxy, propoxy and isopropoxy, trifluoromethyl, nitro and/or halogen such a fluorine, chlorine, bromine and iodine; naphthyl which may be substituted with halogen such as fluorine, chlorine, bromine and iodine; anthraquinonyl, or phthalimide. In the above-mentioned general formula (III), R 1 is hydroxyl; halogen such as fluorine, chlorine, bromine and iodine; alkyl-SO 2 -O- in which the alkyl is a linear or branched alkyl having 1 to 3 carbon atoms such as methyl, ethyl, propyl and isopropyl; or phenyl-SO 2 -O- which may be substituted with a linear or branched alkyl having 1 to 3 carbon atoms such as methyl, ethyl, propyl and isopropyl. The parabanic acid derivatives of the present invention cover pharmaceutically acceptable salts of the compounds represented by the above-mentioned general formula (I). Examples are the salts with an alkali metal such as sodium and potassium; with an alkali earth metal such as calcium and magnesium; with metal such as aluminum; and with bases such as ammonia and organic amines. Those salts may be manufactured, by known methods, from the parabanic acid derivatives of the present invention which is in a free form or mutually converted among the salts. When there are steric isomers such as cis-trans isomer, optical isomer and conformational isomer in a substance of the present invention, the present invention covers any and all of such isomers. The compound of the present invention which was prepared as such was purified by conventional means such as distillation, chromatography and recrystallization and identified by means of elementary analysis, melting point measurement, IR, NMR and MS. [Examples] Method of manufacturing the compounds of the present invention will be illustrated by way of the following examples. Example 1. Sodium hydride (0.89 g) was suspended in 10 mL of N,N-dimethylformamide, a solution of 3.53 g of ethyl 2,4,5-trioxoimidazolidine-3-acetate dissolved in 50 mL of N,N-dimethylformamide was dropped thereinto with stirring at not higher than 0°C and then the mixture was stirred at room temperature for one hour. To the reaction mixture was added a solution of 3.78 g of 2-bromomethyl-5-trifluorometylbenzothiazole dissolved in 40 mL of N,N-dimethylformamide at not higher than 0°C and the mixture was stirred for two hours more. The reaction solution was added to an ice-cooled diluted hydrochloric acid and the mixture was stirred until it was solidified. The solid was filtered, washed with water and then with hexane and recrystallized from ethanol to give ethyl 3-[2-(5-trifluoromethylbenzothiazolyl)-methyl]-2,4,5-trioxoimidazolidine-1-acetate [Compound 1]. Melting point: 150.0-151.0°C IR(KBr): 3001, 1742(C=O), 1430, 1333, 1234, 1115 cm -1 1 H-NMR(DMSO-d 6 ): 1.22(t,J=7.1Hz,3H,CH 3 ), 4.19(q,J=7.1Hz, 2H,O-CH 2 ), 4.39(s,2H,N-CH 2 -CO 2 ), 5.33(s. 2H,CH 2 -Ar), 7.80(d, J=8.4Hz,1H,Ar), 8.35(s,1H,Ar), 8.40 (d,J=8.4Hz,1H,Ar) The same reaction as in Example 1 was carried out to give the following compounds. Ethyl 3-(1-naphtyl methyl)-2,4,5-trioxoimidazolidine-1-acetate [Compound 9]. Melting point: 172.0-175.0°C IR(KBr): 1747(C=O), 1734(C=O), 1446, 1232, 1151, 797, 575 cm -1 1 H-NMR(DMSO-d 6 ): 1.19(t,J=7.0Hz,3H,CH 3 ), 4.15 (q, J=7.0Hz, 2H,C-CH 2 ), 4.43(s,2H,N-CH 2 -CO 2 ), 5.22(s,2H,CH 2 -N), 7.45-7.64(m,4H,Ar) , 7.91(d,J=8.6Hz,1H,Ar), 7.98(d,J=8.6Hz, 1H,Ar), 8.19(d,J=8.6Hz,1H,Ar) Ethyl 3-(2-naphtylmethyl)-2,4,5-trioxoimidazolidine-1-acetate [Compound 10]. Melting point: 149.0-150.0°C IR(KBr): 1734(C=O), 1446, 1238, 1149, 766 cm -1 1 H-NMR(DMSO-d 6 ): 1.19(t,J=7.0Hz,3H,CH 3 ), 4.16(q,J-7.0Hz, 2H,O-CH 2 ), 4.43(s,2H,N-CH 2 -CO 2 ), 4.92(s,2H,CH 2 -N), 7.47(dd, J=8.5,1.8Hz,1H,Ar), 7,52(s,1H,Ar), 7.52(dd,J=9.5,1.8Hz, 1H,Ar), 7.86-7.95(m,4H,Ar) Ethyl 3-[2-(9,10-anthraquinonyl)methyl]-2,4,5-trioxoimidazolidine-1-acetate [Compound 11]. Melting point: 217.0-218.0°C IR(KBr): 1731(C=O), 1674, 1446, 1298, 1147 cm -1 1 H-NMR (DMSO-d 6 ): 1.21(t,J=7.0Hz,3H,CH 3 ), 4.17(q,J=7.0Hz, 2H, O-CH 2 ), 4.43(s,2H,N-CH 2 -CO 2 ), 4,98(s,2H,CH 2 -N), 7.88-7.98(m,3H,Ar), 8.18-8.24(m,H,Ar) Ethyl 3-(2-benzothiazolylmethyl)-2,4,5-trioxoimidazolidine-1-acetate [Compound 12] Melting point: 151.5-153.0°C IR(KBr): 1734(C=O), 1446, 1221, 1147, 770 cm -1 1 H-NMR(DMSO-d 6 ): 1.21 (t,J=7.0Hz,3H,CH 3 ), 4.17(q,J=7.0Hz,2H,O-CH 2 ), 4.47(s,2H,N-CH 2 -CO 2 ), 5.25(s,2H, CH 2 -N), 7.46(ddd,J=7.7,7.7,1.2Hz,1H,Ar), 7.53(ddd,J=7.7, 7.7,1.2Hz,1H,Ar), 7.99 7.97(dd,J=7.7,1.2Hz,1H,Ar), 8.11(dd, J=7.7,1.2Hz,1H,Ar) Ethyl 3-(N-phthalimidemethyl)-2,4,5-trioxoimidazolidine-1-acetate [Compound 13]. Melting point: 197.0-199.0°C IR(KBr): 1743(C=O), 1406, 1336, 1221, 1141, 762, 723 cm -1 1 H-NMR(DMSO-d 6 ): 1.19(t,J=7.0Hz,3H,CH 3 ), 4.15(q,J=7.0Hz, 2H,O-CH 2 ), 4.38(s,2H,N-CH 2 -CO 2 ), 5.39(s,2H,CH 2 -N), 7.82-7.96(m,4H,Ar) Ethyl 3-[1-(2-bromonaphtyl)methyl] -2,4,5-trioxoimidazolidine-1-acetate [Compound 14]. Melting point: 184.5-185.5°C IR(KBr): 1736(C=O), 1446, 1227, 1153, 771 cm -1 1 H-NMR(DMSO-d 6 ): 1.21(t,J=7.0Hz,3H,CH 3 ), 4.17(q,J=7.0Hz, 2H,O-CH 2 ), 4.44(s,2H,N-CH 2 -CO 2 ), 5.04(s,2H,CH 2 -N), 7.56(d, J=8.5Hz,1H,Ar), 7.64(dd,J=7.0,7.0Hz,1H,Ar), 7.72(dd, J=8.5,7.0Hz,1H,Ar), 7.95-8.05(m,2H,Ar), 8.25(d,J=8.5Hz, 1H,Ar) Ethyl 3-[2-(6-nitrobenzothiazolyl)methyl]-2,4,5-trioxoimidazolidine-1-acetate [Compound 15]. Melting point: 183.0-184.0°C IR(KBr): 1743(C=O), 1738(C=O), 1524(NO 2 ), 1444, 1346(NO 2 ), 1225 cm -1 1 H-NMR(DMSO-d 6 ): 1.21(t,J=7.1Hz,3H,CH 3 ), 4.18(q,J=7.1Hz, 2H,O-CH 2 ), 4.48(s,2H,N-CH 2 -CO 2 ), 5.34(s,2H,CH 2 -Ar), 8.19(d, J=9.0Hz,1H,Ar), 8.34(dd,J=9.0,2.4Hz,1H,Ar), 9.22(d, J=2.4Hz,1H,Ar) Ethyl 3-[2-(6-methylbenzothiazolyl)methyl]-2,4,5-trioxoimidazolidine-1-acetate [Compound 16]. Melting point: 155.0-156.0°C IR(KBr): 1738(C=O), 1443, 1402, 1234, 1147 cm -1 1 H-NMR(DMSO-d 6 ); 1.21(t,J=7.1Hz,3H,CH 3 ), 2.44(s,3H,CH 3 ), 4.18(q,J=7.1Hz,2H,O-CH 2 ), 4.47(s,2H,N-CH 2 -CO 2 ), 5.21(s,2H, CH 2 -Ar), 7.34 (d,J=8.2Hz,1H,Ar), ), 7.86(d,J=8.2Hz,1H,Ar), 7.90(s,1H,Ar) Ethyl 3-[2-(5-chlorobenzothiazolyl)methyl]-2,4,5-trioxoimidazolidine-1-acetate [Compound 17]. Melting point: 163.0-163.5°C IR(KBr): 1749(C=O), 1734(C=O), 1441, 1226, 1152, 816 cm -1 1 H-NMR(DMSO-d 6 ): 1.21(t,J=7.1Hz,3H,CH 3 ), 4.18(q,J=7.1Hz, 2H,O-CH 2 ), 4.47(s,2H,N-CH 2 -CO 2 ), 5.26(s,2H,CH 2 -Ar), 7.53(dd,J=8.5,1.9Hz,1H,Ar), 8.09(d,J=1.9Hz,1H,Ar), 8.17(d,J=8.5Hz,1H,Ar) Ethyl 3-[2-(6-chlorobenzothiazolyl)methyl]-2,4,5-trioxoimidazolidine-1-acetate [Compound 18]. Melting point: 181.0-182.5°C IR(KBr): 1734(C=O), 1444, 1405, 1240, 1148, 815 cm -1 1 H-NMR(DMSO-d 6 ): 1.21(t,J=7.1Hz,3H,CH 3 ), 4.17(q,J=7.1Hz, 2H,O-CH 2 ), 4.47(s,2H,N-CH 2 -CO 2 ), 5.25(s,2H,CH 2 -Ar), 7.56(dd,J=8.8,2.2Hz,1H,Ar), 7.99(d,J=8.8Hz,1H,Ar), 8.29(d,J=2.2Hz,1H,Ar) Ethyl 3-[2-(4-chlorobenzothiazolyl)methyl]-2,4,5-trioxoimidazolidine-1-acetate [Compound 19]. Melting point: 186.5-187.5°C IR(KBr): 1735(C=O), 1729(C=O), 1444, 1403, 1240, 1147, 1102, 780, 743 cm -1 1 H-NMR(DMSO-d 6 ): 1.21(t,J=7.0Hz,3H,CH 3 ), 4.17(q,J=7.0Hz, 2H,O-CH 2 ), 4.46(s,2H,N-CH 2 -CO 2 ), 5.28(s,2H,CH 2 -Ar), 7.47(dd,J=8.0,8.0Hz,1H,Ar), 7.64(d,J=8.0Hz,1H,Ar), 8.11(d,J=8.0Hz,1H,Ar) Ethyl 3-[2-(6-fluorobenzothiazolyl)methyl]-2,4,5-trioxoimidazolidine-1-acetate [Compound 20]. Melting point: 154.0-155.0°C IR(KBr): 1734(C=O), 1447, 1228, 1149, 770 cm -1 1 H-NMR(DMSO-d 6 ): 1.21(t,J=7.1Hz,3H,CH 3 ), 4.17(q,J=7.1Hz, 2H,O-CH 2 ), 4.46(s,2H,N-CH 2 -CO 2 ), 5.23(s,2H,CH 2 -Ar), 7.39 (ddd,J=9.2,9.2,2.5Hz,1H,Ar), 8.01(dd,J=9.2,5.0Hz, 1H,Ar), 8.04(dd,J=9.2,2.5Hz,1H,Ar) Ethyl 3-[2-(6-methoxybenzothiazolyl)methyl]-2,4,5-trioxoimidazolidine-1-acetate [compound 21]. Melting point: 150.5-152.0°C IR(KBr); 1736(C=O), 1443, 1259, 1227, 1146, 825 cm -1 1 H-NMR(DMSO-d 6 ): 1.21(t,J=7.1Hz,3H,CH 3 ), 3.83(s,3H,O-CH 3 ), 4.17(q,J=7.1Hz,2H,O-CH 2 ), 4.46(s,2H,N-CH 2 -CO 2 ), 5.18(s,2H, CH 2 -Ar), 7.11(dd.J=9.0,2.6Hz,1H,Ar), 7.68(d,J=2.6Hz, 1H,Ar), 7.86(d,J=9.0Hz,1H,Ar) Ethyl 3- [2-(5-bromobenzothiazolyl)methyl]-2,4,5-trioxoimidazolidine-1-acetate [Compound 22]. Melting point: 157.0-158.0°C (decomp.) IR(KBr): 1751(C=O), 1732(C=O), 1444, 1430 cm -1 1 H-NMR (DMSO-d 6 ) : 1.21(t,J=7.0Hz,3H,CH 3 ), 4.18(q,J=7.0Hz, 2H,O-CH 2 ), 4.47(s,2H,N-CH 2 -CO), 5.26(s,2H,CH 2 -Ar), 7.64(dd,J=8.6,1.8Hz,1H,Ar-H), 8.11(d,J=8.6Hz,1H,Ar-H), 8.22(d,J=1.8Hz,1H,Ar-H) Example 2. The compound 1 (2.1 g) was added to a mixed solution of 6 mL of acetic acid and 2 mL of concentrated hydrochloric acid, the mixture was heated to reflux for two hours, concentrated in vacuo , then 6 mL of acetic acid and 2 mL of concentrated hydrochloric acid were added thereto and the mixture was heated to reflux for one hour. Water was added to the residue obtained by concentrating the reaction mixture and the resulting precipitate was collected by filtration, washed with water, dried and recrystallized from ethanol to give 3-[2-(5-trifluoromethylbenzothiazolyl)-methyl]-2,4,5-trioxoimidazolidine-1-acetic acid [Compound 32]. Melting point: 211.0-212.0°C MS(EI,70eV): 387(M + ,72), 258(43), 230(12), 216(19), 203(80), 56(100) IR(KBr): 2926(OH), 1741(C=O), 1443, 1421, 1333, 1149, 1122 cm -1 1 H-NMR(DMSO-d 6 ): 4.36(s,2H,N-CH 2 -CO 2 ), 5.32(s,2H,CH 2 -Ar), 7.80(d,J=8.4Hz,1H,Ar), 8.37(s,1H,Ar), 8.39(d,J=8.4Hz, 1H,Ar), 13.47(brs,1H,OH) Elementary analysis (C 14 H 8 F 3 N 3 O 5 S 0.1H 2 O): Calculated (C=43.22,H=2.12,N=10.80), Found (C=43.60,H=2.53,N=10.97) The same reaction as in Example 2 was carried out to give the following compounds. 3-(1-naphtylmethyl)-2,4,5-trioxoimidazolidine-1-acetic acid [Compound 40]. Melting point: 225.0-228.0°C IR(KBr): 3000(OH), 1738(C=O), 1722(C=O), 1444, 1400, 1246, 1151, 798 cm -1 1 H-NMR (DMSO-d 6 ): 4.34 (s,2H,N-CH 2 -CO 2 ), 5.21(s,2H,CH 2 -N), 7.34-7.64(m,4H,Ar), 7.90(d,J=7.9Hz,1H,Ar), 7.98(d, J=7.9Hz,1H,Ar), 8.20(d,J=7.9Hz,1H,Ar), 13.42(brs,1H,OH) Elementary analysis (C 16 H 12 N 2 O 5 ): Calculated (C=61.54, H=3.87, N=8.97), Found (C=61.28, H=3.94, N=8.89) 3-(2-naphtylmethyl)-2,4,5-trioxoimidazolidine-1-acetic acid [Compound 41]. Melting point: 192.5-194.0°C IR(KBr) : 3000(OH), 1768(C=O), 1738(CO), 1716(C=O), 1441, 1402, 1250, 1149, 762 cm -1 1 H-NMR(DMSO-d 6 ): 4.42(s,2H,N-CH 2 -CO 2 ), 4.92(s,2H,CH 2 -N), 7.47(dd,J=8.9,2.0Hz,1H/Ar), 7.52(s,1H,Ar), 7.52(dd, J=9.4,2.0Hz,1H,Ar), 7.86-7.94(m,4H,Ar), 13.46(brs,1H,OH) MS m/z: 312(M + ) Elementary analysis (C 16 H 12 N 2 O 5 ) Calculated (C=61.54, H=3.87, N=8.97), Found (C=61.24, H=4.04, N=8.76) 3- [2-(9,10-anthraquinonyl)methyl]-2,4,5-trioxoimidazolidine-1-acetic acid (Compound 42]. Melting point: 236.5-238.5°C IR(KBr): 3100(OH), 1736(C=O) , 1674, 1446, 1300, 1149, 711 cm -1 1 H-NMR(DMSO-d 6 ); 4.32(s,2H,N-CH 2 -CO 2 ), 4.98(s,2H,CH 2 -N), 7.86-7.99(m,3H,Ar), 8.13-8.27(m,H,Ar), 13.41(brs,1H,OH) Elementary analysis (C 20 H 12 N 2 O 7 0.5H 2 O): Calculated (C=59.86, H=3.27, N=6.98), Found(C=59.91, H=3.42, N=6.82) 3-(2-benzythiazolylmethyl)-2,4,5-trioxoimidazolidine-1-acetic acid [Compound 43]. Melting point: 264.0-265.0°C (decomp.) IR(KBr): 3100(OH), 1736(C=O), 1443, 1402, 1215, 1149, 763 cm -1 1 H-NMR(DMSO-d 6 ): 4.38(s, 2H,N-CH 2 -CO 2 ), 5.25(s,2H,CH 2 -N), 7.46(dd.J=7.4,7.4Hz,1H,Ar), 7.52(dd,=7.4,7.4Hz,1H,Ar), 7.99(d,J=7.4Hz,1H,Ar), 8.12(d,J=7.4Hz,1H,Ar), 13.43(brs, 1H,OH) MS m/z: aaa(M + ) Elementary analysis (C 13 H 9 N 3 O 5 S) : Calculated (C=48.90, H=2.84, N=13.16), Found (C=48.92, H=2.90, N=13.06) 3-(N-phthalimidemethyl)-2,4,5-trioxoimidazolidine-1-acetic acid [Compound 44]. Melting point: 266.0-268.0°C (decomp.) IR(KBr): 3000(OH), 1740(C=O) 1412, 1331, 1169, 926, 731 590 cm -1 1 H-NMR(DMSO-d 6 ): 4.28(s,2H,N-CH 2 -CO 2 ), 5.39(s,2H,CH 2 -N), 7.85-7.95(m,4H,Ar), 13.41(brs,1H,OH) MS m/z: 331(M + ) Elementary analysis (C 14 H 9 N 3 O 7 ): Calculated (C=50.77, H=2.74, N=12.69), Found (C=50.65,H=2.82,N=12.72) 3-[1-(2-bromonaphtyl)methyl]-2,4,5-trioxoimidazolidine-1-acetic acid [Compound 45]. Melting point: 205.0-210.0°C (decomp.) IR(KBr): 3000(OH), 1738(C=O), 1720(C=O), 1433, 1153, 760 cm -1 1 H-NMR(DMSO-d 6 ): 4.33(s,2H,N-CH 2 -CO 2 ), 5.04(s,2H,CH 2 -N), 7.55(d,J=8.9Hz,1H,Ar), ), 7.64(dd,J=8.1,7.4Hz,1H,Ar), 7.72(dd,J=8.1,7.4Hz,1H,Ar), 7.98(d,J=8.1Hz,1H,Ar), 8.00(d,J=8.1Hz,1H,Ar), 8.25(d,J=8.9Hz,1H,Ar), 13.46(brs,1H,OH) MS m/z: 392(M + ( 81 Br)), 392(M + ( 79 Br)) Elementary analysis (C 16 H 11 BrN 2 O 5 ): Calculated (C=49.13, H=2.83, N=7.16), Found (C=48.89, H=2.97, N=6.98) 3-[2-(6-nitrobenzothiazolyl)methyl]-2,4,5-trioxoimidazolidine-1-acetic acid [Compound 46]. Melting point: 130.0-131.0°C (decomp.) MS(EI,70eV): 364(M + ,79), 235(44), 207(11), 180(47), 56(100) IR(KBr): 3000(OH), 1745(C=O), 1734(C=O), 1525(NO 2 ), 1435, 1344(NO 2 ) cm -1 1 H-NMR(DMSO-d 6 ): 4.36(s,2H,N-CH 2 -CO 2 ), 5.34(s,2H,CH 2 -Ar), 8.19(d,J=9.0Hz,1H,Ar), 8.34(dd,J=9.0,2.3Hz,1H,Ar), 9.21(d,J=2.3Hz,1H,Ar), 13.47(brs,1H,OH) Elementary analysis (C 13 H 8 N 4 O 7 S): Calculated (C=42.86, H=2.21, N=15.38), Found (C=42.90, H=2.33, N=15.15) 3-[2-(6-methylbenzothiazolyl)methyl] -2,4,5-trioxoimidazolidine-1-acetic acid [Compound 47]. Melting point: 277.0-278.0°C MS(EI,70eV): : 333(M + ,100), 204(50), 176(24), 162(26), 149(86), 56(63) IR(KBr): 3000(OH), 1738(C=O), 1441, 1402, 1213, 1151, 764 cm -1 1 H-NMR(DMSO-d 6 ): 2.44(s,3H,CH 3 ), 4.35(s,2H,N-CH 2 -CO 2 ), 5.21(s,2H,CH 2 -Ar), 7.34(d,J=8.3Hz,1H,Ar), 7.86(d,J=8.3Hz, 1H,Ar), 7.89(s,1H,Ar), 13.47(brs,1H,OH) Elementary analysis (C 14 H 11 N 3 O 5 S): Calculated (C=50.45, H=3.33, N=12.61), Found (C=50.39, H=3.30, N=12.66) 3-[2-(5-chlorobenzothiazolyl)methyl]-2,4,5-trioxoimidazolidine-1-acetic acid [Compound 48]. Melting point: 265.0-268.0°C (decomp.) MS(EI,70eV): 355(M + ( 37 Cl),21), 353(M + ( 35 Cl),59), 224(44), 196(20), 182(19), 169(64), 56(100) IR(KBr): 3006(OH), 1782(C=O), 1741(C=O), 1429, 1351, 1213, 1120, 886, 799, 758 cm -1 1 H-NMR(DMSO-d 6 ): 4.36(s,2H,N-CH 2 -CO 2 ), 5.26(s,2H,CH 2 -Ar), 7.52(dd,J=8.6,2.0Hz,1H,Ar), 8.10(d,J=2.0Hz,1H,Ar), 8.16(d,J=8.6Hz,1H,Ar), 13.45(brs,1H,OH) Elementary analysis (C 13 H 8 ClN 3 O 5 S): Calculated (C=44.14, H=2.28, N=11.88), Found (C=44.20, H=2.46, N=11.80) 3-[2-(6-chlorobenzothiazolyl)methyl]-2,4,5-trioxoimidazolidine-1-acetic acid [Compound 49]. Melting point: 265.0-266.0°C MS(EI,70eV): 355(M + ( 37 Cl),32), 353(M + ( 35 Cl),59) 226(20), 224(52), 196(23), 182(25), 171(28), 169(76), 56(100) IR(KBr): 3000(OH), 1746(C=O), 1734(C=O), 1435, 1398, 1345, 1143, 1117, 757 cm -1 1 H-NMR(DMSO-d 6 ): 4.36(s,2H,N-CH 2 -CO 2 ), 5.25(s,2H,CH 2 -Ar), 7.56(d,J=8.7Hz,1H,Ar), 7.99(d,J=8.7Hz,1H,Ar), 8.29(s, 1H,Ar), 13.45(brs.1H,OH) Elementary analysis (C 13 H 8 ClN 3 O 5 S): Calculated (C=44.14, H=2.28, N=11.88), Found (C=43.98, H=2.27, N=11.89) 3-[2-(4-chlorobenzothiazolyl)methyl]-2,4,5-trioxoimidazolidine-1-acetic acid [Compound 50]. Melting point: 238.0-240.0°C MS(EI,70eV): 355(M + ( 37 Cl),32), 353(M + ( 35 Cl),82), 226(16), 224(41), 196(17), 182(17), 171(24), 169(64), 56(100) IR(KBr): 2900(OH), 1732(C=O), 1442, 1401, 1201, 1146, 778, 762, 607 cm -1 1 H-NMR(DMSO-d 6 ): 4.35(s,2H,N-CH 2 -CO 2 ), 5.27(s,2H,CH 2 -Ar), 7.47(dd,J=8.0,8.0Hz,1H,Ar), 7.63(d,J=8.0Hz,1H,Ar), 8.11(d,J=8.0Hz,1H,Ar), 13.41(brs,1H,OH) Elementary analysis (C 13 H 8 ClN 3 O 5 S): Calculated (C=44.14, H=2.28, N=11.88), Found (C=44.32, H=2.47, N-11.56) 3-[2-(6-fluorobenzothiazolyl)methyl]-2,4,5-trioxoimidazolidine-1-acetic acid [Compound 51]. Melting point: 261.0-262.0°C MS(EI,70eV): 337(M + ,72) 208(57), 180(30), 166(34), 153(100) IR(KBr): 2900(OH), 1744(C=O), 1721(C=O), 1521, 1439, 1406, 1204, 1154, 1116, 769, 631 cm -1 1 H-NMR(DMSO-d 6 ): 4.34(s,2H,N-CH 2 -CO 2 ), 5.22 (s,2H,CH 2 -Ar), 7.34-7.41(m,1H,Ar), 7.97-8.06(m,2H,Ar), 13.43(brs,1H,OH) Elementary analysis (C 13 H 8 FN 3 O 5 S): Calculated (C=46.29, H=2.39, N=12.46), Found (C=46.59, H=2.59, N=12.68) 3-[2-(6-methoxybenzothiazolyl)methyl]-2,4,5-trioxoimidazolidine-1-acetic acid [Compound 52]. Melting point: 270.0-271.0°C MS(EI,70eV): 349(M + ,100), 220(47), 192(28), 178(28), 165(74), 56(53) IR(KBr): 3000(OH), 1734(C=O), 1443, 1421, 1223, 1149 cm -1 1 H-NMR(DMSO-d 6 ): 3.83(s,3H,O-CH 3 ), 4.34(s,2H,N-CH 2 -CO 2 ), 5.18(s,2H,CH 2 -Ar), 7.11(dd,J=8.9,2.4Hz,1H,Ar), 7.67(d, J=2.4Hz,1H,Ar), 7.87(d,J-8.9Hz,1H,Ar) Elementary analysis (C 14 H 11 N 3 O 6 0.1H 2 O): Calculated (C=47.89, H=3.22, N=12.97), Found (C=47.87, H=3.10 N=11.53) 3-[2-(5-bromobenzothiazolyl)methyl]-2,4,5-trioxoimidazolidine-1-acetic acid [Compound 53]. Melting point: 272.0-273.0°C (decomp.) MS(EI,70eV) m/z: 293(M + ,10), 275(4), 157(100), 136(36), 120(28), 90(54), 74(47), 56(43) IR(KBr): 3000(OH), 1740(C=O), 1428, 1400, 1211 cm -1 1 H-NMR(DMSO-d 6 ): 4.34 (s,2H,N-CH 2 -CO), 5.26(s,2H,CH 2 -Ar), 7.64(dd,J=8.6,1.6Hz,1H,Ar-H), 8.11(d,J=8.6Hz,1H,Ar-H), 8.23(d,J=1.6Hz,1H,Ar-H), 13.20(brs,1H,COOH) Elementary analysis (C 13 H 8 BrN 3 O 5 S): Calculated (C=39.21, H=2.03, N=10.55), Found (C=39.41, H=1.86, N=10.12) Pharmacological action of the compounds of the present invention will be mentioned as follows. (1) Action of inhibiting an aldose reductase. Action of the compounds of the present invention for inhibiting an aldose reductase was investigated using the aldose reductase which was prepared from lenses of rats. Thus, a compound was added to a reaction system comprising a phosphate buffer, NADPH and aldose reductase and, after confirming for several minutes that the absorbancies became stable, glyceraldehyde was added thereto and a decrease in the absorbance at 340 nm with a lapse of time was measured whereby the inhibitory action of the compound to the aldose reductase was determined. Examples of the results are given in Table 1 in which the inhibiting rate to the aldose reductase is the value when the concentration of the compound was 1 x 10 -7 M. Compound No. Inhibiting rate Compound No. Inhibiting rate Compound 32 58% Compound 47 33% Compound 41 42% Compound 48 71% Compound 42 27% Compound 49 58% Compound 43 42% Compound 50 83% Compound 44 26% Compound 51 63% Compound 45 60% Compound 53 32% Compound 46 48% It is clear from the above-mentioned results of the pharmacological tests, the parabanic acid derivatives of the present invention exhibit an excellent inhibitory action to aldose reductase with a low toxicity whereby they are very useful as therapeutic agents for diabetic complications. Thus, they are useful as drugs for therapy and prevention of various types of diabetic complications caused by an excessive accumulation of intracellular sorbitol such as diabetic neuropathy, diabetic cataract and retinopathy, diabetic nephropathy, diabetic dermopathy and other diabetic microangiopathy. In the meanwhile, an inhibitory action of the compounds of the present invention to an aldehyde reductase obtained from rat kidney was measured using the compounds at the concentration of 1 x 10 -4 M but the inhibition was hardly noted. Thus, the compounds of the inhibition was hardly noted. Thus, the compounds of the present invention having a high enzyme selectivity to aldose reductase participating in the production of sorbitol which induces diabetic complications are with low toxicity and high safety and, therefore, they are particularly useful for the therapy of the above-mentioned chronic diseases which require an administration of a drug for long period. The substance of the present invention can be made into pharmaceutical preparations by a combination with a suitable pharmaceutical carriers or diluents. They can be made into various types of preparations by common methods and are able to be made into solid, semisolid, liquid or aerosol formulations for administrations by oral or parenteral means. In preparing the preparations, the substance of the present invention may be used either solely or jointly together with other pharmaceutically-active components. In the case of the preparations for oral administration, the substance of the present invention as it is or together with commonly-used excipients such as a suitable additive (e.g. lactose, mannitol, corn starch, potato starch, etc.) is mixed with binders such as crystalline cellulose, cellulose derivatives, gum arabicum, corn starch, gelatin, etc., disintegrating agents such as corn starch, potato starch, potassium carboxymethylcellulose, etc., lubricating agents such as talc, magnesium stearate, etc. and others including bulking agents, moisturizing agents, buffers, preservatives, perfumes and the like to give tablets, diluted powders, granules or capsules. Alternatively, suppositories may be prepared by mixing with fatty/oily bases (e.g. cacao butter), emulsified bases, water-soluble bases (e.g. Macrogol), hydrophilic bases, etc. In the case of injections, it is possible to prepare the solutions or the suspensions in an aqueous and nonaqueous solvents such as distilled water for injection, physiological saline solution, Ringer's solution, plant oil, synthetic fatty acid glycerides, higher fatty acid esters, propylene glycol, etc. In case of inhalations or aerosol preparations, the compound of the present invention in the form of a liquid or minute powder can be filled up in an aerosol container with gas or liquid spraying agent, and if desired, with conventional adjuvants such as humidifying agents or dispersing agent. They can also be used as pharmaceuticals for a non-pressurized preparation such as in a nebulizer or an atomizer. In order to make the compounds of the present invention into collyriums, they can be prepared as a solution or suspension together with an aqueous solvent such as sterile, purified water and physiologically saline solution, or a non-aqueous solvent for injection, if desired, with preservations, sterilizers, etc. It is also possible, depending upon the type of the disease, to prepare the pharmaceutical preparations which are other than those which were mentioned already and are suitable for the therapy such as, for example, ointments, poultices, etc. The preferred dose of the substance of the present invention may vary depending upon the object to be administered the patient, form of the preparation, method for the administration, term for the administration, etc. and, in order to achieve a desired effect, 10-3,000 mg per day, preferably 20-1,500 mg per day may be usually given to common adults by oral route. In the case of a parenteral administration such as by injection, it is preferred that, due to the influence of the absorption, etc., a level of from 1/3 to 1/10 of the above-given dose by oral route is administered.

Claims: A parabanic acid derivative represented by the general formula (I) or a pharmaceutically acceptable salt thereof, wherein: R is hydrogen, C 1-4 alkyl or benzyl; X is benzothiazolyl which may be substituted with C 1-3 alkyl, C 1-3 alkoxy, trifluoromethyl, nitro and/or halogen, naphthyl which may be substituted with nitro and/or halogen, anthraquinonyl, or phthalimide. A parabanic acid derivative according to Claim 1 or a pharmaceutically acceptable salt thereof for use as a medicament. A pharmaceutical composition comprising at least one parabanic acid derivative according to Claim 1 or a pharmaceutically acceptable salt thereof and a pharmacologically acceptable carrier. A method for preparing a parabanic acid derivative according to Claim 1, comprising the step of condensing a compound of the general formula (II) wherein R is hydrogen, C 1-4 alkyl or benzyl; with a compound represented by the general formula (III) X-CH 2 -R 1 wherein X is as defined in Claim 1 and R 1 is hydroxyl, halogen, C 1-3 alkyl-SO 2 -O- or phenyl-SO 2 -O- which may be substituted with C 1-3 alkyl, and optionally subjecting the condensation product to hydrolysis. The use of a parabanic acid according to Claim 1 or a pharmaceutically acceptable salt thereof for the manufacture of a medicament for the treatment of a diabetic complication.

Inventors: KOTANI TAKAYUKI, NAGAKI YASUHIRO, OKAMOTO KAORU, KOTANI, TAKAYUKI, NAGAKI, YASUHIRO, OKAMOTO, KAORU, Kotani, Takayuki, c/o Nippon Zoki Pharm. Co., Ltd., Nagaki, Yasuhiro, c/o Nippon Zoki Pharm. Co., Ltd., Okamoto, Kaoru, c/o Nippon Zoki Pharm. Co., Ltd.
Applicants: NIPPON ZOKI PHARMACEUTICAL CO, NIPPON ZOKI PHARMACEUTICAL CO., LTD.
Application year: 1995
Main classification: C07D233
IPC codes: C07D233, C07D409, C07D417, C07D403, C07D401