Abstract:
New Pyrimidinetrione derivatives represented by formula (I), wherein R 1  and R 2  are defined in the description, composition thereof, and methods of preparation are described. The compounds are useful in the treatment of disease involving metalloproteinases.

Description:
[0001]     The present invention relates to new pyrimidinetrione derivatives, to their method of preparation, to compositions comprising the compounds, to the compounds for use as medicament and their use in therapy e.g. in preparation of medicament for the treatment of inflammation, cancer and other disorders.  
       BACKGROUND OF THE INVENTION  
       [0002]     Pyrimidinetrione derivatives are inhibitors of zinc metalloendopeptidases, especially those belonging to the class of matrix metalloproteinases (MMP).  
         [0003]     Matrix metalloproteinases (MMPs) are a family of about 24 homologous proteins sharing the capacity to cleave peptidic bounds of many of the structural proteins of the extra-cellular matrix.  
         [0004]     They have a structure-conserved active site in which a zinc atom plays an essential role.  
         [0005]     The minimum structure configuration of MMPs is a catalytic domain and a pro peptide which is hiding the catalytic site in the inactivated, pro-forms of the enzymes. Activation is obtained by catalytic cleavage of the pro-domain. Most of the MMPs have an additional hemopexin domain linked to the C-terminal end of the catalytic domain through a so-called hinge peptide. This hemopexin (PEX) domain has the ability to interact with numerous proteic/sugar substrates, which affects the net activity of the enzyme. All the MMPs are secreted in the interstitial medium, but 6 MMPs are anchored to the cell membrane (MT1-6-MMP).  
         [0006]     MMPs are classified either following their structure or based on their substrate specificity. The following sub-families have thus been defined: collagenases (MMP1, 8, 13, 18), stromelysins (MMP 3, 10, 11), metalloelastase (MMP12), gelatinases (MMP2, 9), MT-MMPs (MMP 14, 15, 16, 24, 25).  
         [0007]     The MMPs are known for their role in numerous physiological processes such as wound healing, ovulation, endometrial cycle, embryo development, trophoblast implantation and bone and cartilage remodelling.  
         [0008]     They are also playing a major role in many pathologies, i.e. arthritis, tumour growth, progression and invasion, osteoporosis, ocular abnormal angiogenesis, multiple sclerosis, asthma, atherosclerosis, corneal ulceration, periodontal disease and the like.  
         [0009]     Pyrimidinetrione derivatives are already known in the art. WO 01/25217 described pyrimidine-2,4,6-trione derivatives as inhibitors of matrix metalloproteinases but such compounds have in general a low solubility in water and therefore a bad oral biodisponibility. Toxicity by photosensitization of some of them is wellknown.  
         [0010]     We have now found new pyrimidinetrione derivatives with improved activity as matrix metallo-proteinase inhibitors over the compounds described in WO01/25217, putatively lower toxicity by photosensitization and better solubility in water. 
     
    
     DESCRIPTION OF THE INVENTION  
       [0011]     The present invention concerns new pyrimidinetriones of general formula I:  
                         
 
 wherein 
 
         [0012]     R 1  is hydrogen; or R 1  forms with R 2  and the nitrogen atom a succinimide (pyrrolidinedione) cycle, a glutarimide (piperidinedione) cycle or a perhydroazepinedione cycle.  
         [0013]     R 2  is formyl, a straight or branched C 1-6 -acyl, a straight or branched carboxy-C 1-6 -alkylcarbonyl, a straight or branched C 1-6 -alkoxycarbonyl, a straight or branched C 1-6 -alkylaminocarbonyl;  
         [0000]     or R 2  forms with R 1  and the nitrogen atom a succinimide (pyrrolidinedione) cycle, a glutarimide (piperidinedione) cycle or a perhydroazepinedione cycle.  
         [0014]     The present invention also encompasses  
         [0000]     a pharmaceutical acceptable salt thereof with a pharmaceutically acceptable acid or base; an optical isomer thereof, a tautomeric form thereof, or a polymorphic form thereof.  
         [0015]     The salts include pharmaceutically acceptable acid addition salts, pharmaceutically acceptable metal salts, such as hydrochloric, hydrobromic, hydroiodic, phosphoric, sulfuric, trifluoroacetic, oxalic, maleic, pyruvic, malonic, succinic, citric, tartaric, fumaric, mandelic, benzoic, cinnamic, methanesulfonic, ethanesulfonic, picric and the like and include acids related to the pharmaceutically acceptable salts listed in Journal of Pharmaceutical Sciences 66, 2 (1977) and incorporated herein by reference, or lithium, sodium, potassium, magnesium and the like.  
         [0016]     The term “C 1-6 -alkyl” as used herein, alone or in combination, refers to a straight or branched hydrocarbon chain having 1-6 carbon atoms such as e.g. methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, hexyl, isobutyl, 1,2-dimethylpropyl and the like.  
         [0017]     The term “C 1-6 -acyl” as used herein refers to a monovalent substituent comprising a C 1-6 -alkyl group linked through a carbonyl group; such as e.g. acetyl, propionyl, butyryl, isobutyryl, pivaloyl, valeryl, and the like.  
         [0018]     The term “carboxy-C 1-6 -alkylcarbonyl” as used herein refers to a monovalent substituent comprising a carboxy group (—COOH) linked through a C 1-6 -alkyl group which in turn is linked through a carbonyl group; such as carboxyethylcarbonyl (or succinyl), carboxypropylcarbonyl (or glutaryl), carboxybutylcarbonyl, and the like.  
         [0019]     The term “C 1-6 -alkoxycarbonyl” as used herein refers to a monovalent substituent comprising a C 1-6 -alkoxy group linked through a carbonyl group; such as e.g. methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, sec-butoxycarbonyl, tert-butoxycarbonyl and the like.  
         [0020]     The term “C 1-6 -alkylaminocarbonyl” as used herein refers to a monovalent substituent comprising a C 1-6 -alkyl group linked through an aminocarbonyl group; such as e.g. methylaminocarbonyl, ethylaminocarbonyl, propylaminocarbonyl, sec-butylaminocarbonyl, tert-butylaminocarbonyl and the like.  
         [0021]     The term “pyrrolidinedione” as used herein refers to a saturated five-membered ring comprising one nitrogen atom and bearing two carbonyl groups in each ortho position of the nitrogen atom.  
         [0022]     The term “piperidinedione” as used herein refers to a saturated six-membered ring comprising one nitrogen atom and bearing two carbonyl groups in each ortho position of the nitrogen atom.  
         [0023]     The term “perhydroazepinedione” as used herein refers to a saturated seven-membered ring comprising one nitrogen atom and bearing two carbonyl groups in each ortho position of the nitrogen atom.  
         [0024]     Preferred compounds of the invention are selected from the group consisting of: 
    N-{4-[4-(5-(1,1′-biphenyl)-4-yl-2,4,6-trioxoperhydropyrimidin-5-yl)piperazin-1-yl]-phenyl}succinamic acid;     4-{4-[4-(5-(1,1′-biphenyl)-4-yl-2,4,6-trioxoperhydropyrimidin-5-yl)piperazin-1-yl]-phenylcarbamoyl}butyric acid;     5-(1,1′-biphenyl)-4-yl-5-{4-[4-(2,5-dioxopyrrolidin-1-yl)phenyl]piperazin-1-yl}pyrimidine-2,4,6(1H,3H,5H)-trione;     5-(1,1′-biphenyl)-4-yl-5-{4-[4-(2,5-dioxopiperidin-1-yl)phenyl]piperazin-1-yl}pyrimidine-2,4,6(1H,3H,5H)-trione;     N-{4-[4-(5-(1,1′-biphenyl)-4-yl-2,4,6-trioxoperhydropyrimidin-5-yl)piperazin-1-yl]-phenyl}acetamide;     N-{4-[4-(5-(1,1′-biphenyl)-4-yl-2,4,6-trioxoperhydropyrimidin-5-yl)-piperazin-1-yl]phenyl}formamide.    
 
         [0031]     The compounds of the present invention inhibit metalloproteinases which make them useful in the treatment of various diseases. Indeed, MMPs are playing a major role in many pathologies, i.e. arthritis, tumour growth, progression and invasion, osteoporosis, ocular abnormal angiogenesis, multiple sclerosis, asthma, atherosclerosis and the like.  
         [0032]     Accordingly, in another aspect the invention relates to a compound of the general formula I or a pharmaceutically acceptable salt thereof for therapeutic use, particularly for therapeutic use in the treatment of diseases involving metalloproteinases such as arthritis, tumour growth, progression and invasion, osteoporosis, ocular abnormal angiogenesis, multiple sclerosis, asthma, atherosclerosis and the like.  
         [0033]     The invention also relates to the use of a compound of the general formula I, a pharmaceutical acceptable salt thereof with a pharmaceutically acceptable acid or base, an optical isomer thereof, a tautomeric form thereof, or a polymorphic form thereof for preparing a medicament, particularly for the treatment of diseases involving metalloproteinases.  
         [0034]     The treatment of diseases involving metalloproteinases comprises administering to a patient an amount of one or more compounds of the invention. As used herein, the term treatment is intended to refer to prevention, amelioration, or reduction in severity of a symptom involving metalloproteinases.  
         [0035]     The compounds of the invention may be administered singly or in combination. Typically the compounds of the invention are administered as a dose in an amount of 0.05 mg to 1000 mg per day, preferably from 0.1 mg to 500 mg per day and most preferably from 0.1 mg to 200 mg per day. However, other amounts, including substantially lower or higher amounts, may also be administered. The compounds of the invention may be administered to a human subject intramuscularly, subcutaneously, intravenously or by any other route of administration.  
         [0036]     In yet another aspect, the present invention also relates to methods of preparing the compounds of the present invention.  
         [0037]     A first method comprises a step of: 
 
 a) reacting a compound of formula II:  
                         
 
 which is obtained as described by Daniewski et al., Organic Research &amp; Development 2004, 8, 411-414 and incorporated herein by reference, with a compound of formula III:  
                         
 
 wherein R 1  and R 2  are defined as above, to form a compound of the general formula I. 
 
         [0038]     The compound of formula III can be obtained as described in scheme 1, wherein tert-butyl 4-(4-aminophenyl)piperazine-1-carboxylate (IV) obtained as described by Koshio et al., Bioorg. Med. Chem. 2004, 12, 2179-2191 and incorporated herein by reference, is reacted in step i with an appropriate anhydride ((R′CO) 2 O or HCOOCOCH 3 ), chloroformiate (R′OCOCl) or isocyanate (R′NCO) wherein R′ is a straight or branched C 1-6  alkyl chain to give an intermediate of general formula V. When succinic anhydride or glutaric anhydride is used, ring closure occurred by using carbonyldiimidazole in presence of triethylamine. Deprotection in step ii by trifluoroacetic acid afforded compound of the general formula III.  
                         
 
         [0039]     A second method comprises a step of: 
 
 b) reacting a compound of formula VI:  
                         
 
 which is obtained from reduction of the corresponding nitro derivative (synthesized as described by Daniewski et al. in Organic Research &amp; Development 2004, 8, 411-414) by catalytic hydrogenation, with an appropriate chloroformiate (R′OCOCl), isocyanate (R′NCO) or anhydride selected from the group consisting of (R′CO) 2 O, HCOOCOCH 3 , succinic anhydride, glutaric anhydride or perhydrooxepine-2,7-dione, wherein R′ is a straight or branched C 1-6  alkyl chain, optionally followed by a ring closure, as reported on scheme 1 (step i.2), to form a compound of the general formula I. 
 
         [0040]     A third method of preparing the compounds according to the invention comprises a step of 
 
 c) reacting a compound of formula II, which is obtained as described by Daniewski et al. in Organic Research &amp; Development 2004, 8, 411-414 and incorporated herein by reference  
                         
 
 with a compound such as VII, commercially available  
                         
 
 to obtain the compound of formula VI, which is reacted with an appropriate chloroformiate (R′OCOCl), isocyanate (R′NCO) or anhydride selected from the group consisting of (R′CO) 2 O, HCOOCOCH 3 , succinic anhydride, glutaric anhydride or perhydrooxepine-2,7-dione, wherein R′ is a straight or branched C 1-6  alkyl chain, optionally followed by a ring closure, as reported on scheme 1 (step i.2), to form a compound of the general formula I. 
 
       EXAMPLES  
       [0041]     The methods to prepare the compounds of formula I are illustrated in the following examples which, however are not to be construed as limiting.  
       Example 1  
       [0042]     Two ways for the preparation of product (VI) as intermediate product in method 2 and 3 of the present invention.  
       5-[4-(4-Aminophenyl)piperazin-1-yl]-5-[1,1′-biphenyl]-4-ylpyrimidine-2,4,6(1H,3H,5H)-trione (above product VI)  
       [0000]     Method A:  
         [0043]     5-[1,1′-Biphenyl]-4-yl-5-[4-(4-nitrophenyl)-1-piperazin-1-yl]-pyrimidine-2,4,6(1H,3H,5H)-trione (500 mg) was dissolved in hot ethanol (100 ml). 10% Pd/C (50 mg) was added to the solution. The mixture was placed in a Paar apparatus for 2 hours under 4 bars hydrogen pressure at 50° C. After hydrogenation, ethanol was removed under reduced pressure. The residue was dissolved in acetone (250 ml). The 10% Pd/C was removed by filtration over a double 602H filter. 5-[1,1′-Biphenyl]-4-yl-5-[4-(4-aminophenyl)-1-piperazinyl]-pyrimidine-2,4,6(1H,3H,5H)-trione was precipitated by addition of water. The precipitate was collected by filtration. The title compound was dried in a vacuum system (containing NaOH pellets) at room temperature: melting point: 268-269° C.; IR: 3372, 3201, 2965, 2843, 1702, 1626, 1582, 1515, 1454, 1341, 1230.  
         [0000]     Method B:  
         [0044]     5-[1,1′-Biphenyl]-4-yl-5-bromopyrimidine-2,4,6(1H,3H,5H)-trione (100 mg) was dissolved in methanol (4 ml) under nitrogen. 1-(4-Aminophenyl)piperazine (50 mg) and potassium carbonate (40 mg) was added to the solution. The mixture was refluxed for 2 hours. After filtration and elimination of the solvent, the crude product was purified by column chromatography using EtOAc/MeOH 18:2 as the eluent. The compound was found to be identical to that obtained by method A (melting point and IR).  
       Example 2  
     Preparation of  
     N-{4-[4-(5-(1,1′-Biphenyl)-4-yl-2,4,6-trioxoperhydropyrimidin-5-yl)piperazin-1-yl]-phenyl}succinamic acid  
       [0045]     Succinic anhydride (200 mg) was dissolved in dimethylformamide (5 ml). 5-[4-(4-Aminophenyl)piperazin-1-yl]-5-[1,1′-biphenyl]-4-ylpyrimidine-2,4,6(1H,3H,5H)-trione (500 mg) was added to the solution. The mixture was stirred at room temperature for 2 hours. The solvent was removed under reduced pressure. The resulting oily residue was triturated with ethyl acetate (15 ml). The precipitate obtained was stirred under reflux in ethyl acetate (15 ml) for 15 minutes and finally collected by filtration, washed with ethyl acetate and dried; melting point: 246-247° C.; IR: 3349, 2832, 1728, 1670, 1610, 1517, 1403, 1330, 1309, 1260, 1230, 1178 cm −1 ;  1 H-NMR (DMSO d 6 ) δ (ppm) 2.50 (m, 4H), 2.80 (m, 4H), 3.10 (m, 4H), 6.85 (d, 2H), 7.35-7.50 (m, 5H), 7.55 (d, 2H), 7.70 (d, 2H), 7.75 (d, 2H), 9.70 (s, 1H), 11.70 (s, 2H), 12.10 (s, 1H).  
       Example 3  
     Preparation Of  
     4-{4-[4-(5-(1,1′-Biphenyl)-4-yl-2,4,6-trioxoperhydropyrimidin-5-yl)piperazin-1-yl]-phenylcarbamoyl}butyric acid  
       [0046]     Glutaric anhydride (200 mg) was dissolved in dimethylformamide (5 ml). 5-[4-(4-Aminophenyl)piperazin-1-yl]-5-[1,1′-biphenyl]-4-ylpyrimidine-2,4,6(1H,3H,5H)-trione (500 mg) was added to the solution. The mixture was stirred at room temperature for 2 hours. The solvent was removed under reduced pressure. The resulting oily residue was triturated with ethyl acetate (15 ml). The precipitate obtained was stirred under reflux in ethyl acetate (15 ml) for 15 minutes and finally collected by filtration, washed with ethyl acetate and dried: melting point: 268-269° C.; IR: 3343, 3191, 3079, 2968, 2836, 1722, 1654, 1603, 1540, 1515, 1335, 1312, 1226 cm −1 ;  1 H-NMR (DMSO d 6 ) δ (ppm) 1.80 (m, 2H), 2.25 (m, 4H), 2.80 (m, 4H), 3.10 (m, 4H), 6.85 (d, 2H), 7.35-7.50 (m, 5H), 7.55 (d, 2H), 7.70 (d, 2H), 7.75 (d, 2H), 9.70 (s, 1H), 11.70 (s, 2H), 12.05 (s, 1H).  
       Example 4  
     Preparation of  
     5-(1,1′-Biphenyl)-4-yl-5-{4-[4-(2,5-dioxopyrrolidin-1-yl)phenyl]piperazin-1-yl}pyrimidine-2,4,6(1H,3H,5H)-trione  
       [0047]     N-{4-[4-(5-(1,1′-Biphenyl)-4-yl-2,4,6-trioxoperhydropyrimidin-5-yl)piperazin-1-yl]-phenyl}succinamic acid (500 mg) was dissolved in anhydrous tetrahydrofuran (20 ml). 1,1′-Carbonyldiimidazole (250 mg) was added to the solution. The mixture was stirred at room temperature for 2 hours. Triethylamine (0.1 ml) was added to the solution. The mixture was stirred at room temperature for 2 hours. The solvent was removed under reduced pressure. Ethyl acetate (20 ml) was added to the residue. A solution of sodium bicarbonate 1% (w/w) was added to the mixture. The mixture was stirred at room temperature for 2 hours. The solid was collected by filtration. The organic layer was dried with anhydrous MgSO 4 . Ethyl acetate was removed under reduced pressure. The solids were put together. The compound was stirred in water for 1 hour and then collected by filtration and dried in a vacuum system (containing NaOH pellets) at room temperature: melting point: 310-311° C.; IR: 3202, 3099, 2987, 2849, 1715, 1610, 1450, 1377, 1332, 1315, 1242, 1164 cm −1 ;  1 H-NMR (DMSO d 6 ) δ (ppm) 2.75 (s, 4H), 2.80 (m, 4H), 3.20 (m, 4H), 7.00 (d, 2H), 7.05 (d, 2H), 7.40 (t, 1H), 7.50 (t, 2H), 7.55 (d, 2H), 7.70 (d, 2H), 7.75 (d, 2H), 11.70 (s, 2H).  
       Example 5  
     Preparation of  
     5-(1,1′-Biphenyl)-4-yl-5-{4-[4-(2,5-dioxopiperidin-1-yl)phenyl]piperazin-1-yl}pyrimidine-2,4,6(1H,3H,5H)-trione  
       [0048]     4-{4-[4-(5-(1,1′-Biphenyl)-4-yl-2,4,6-trioxoperhydropyrimidin-5-yl)piperazin-1-yl]phenylcarbamoyl}butyric acid (500 mg) was dissolved in anhydrous tetrahydrofuran (20 ml). 1,1′-Carbonyldiimidazole (250 mg) was added to the solution. The mixture was stirred at room temperature for 2 hours. Triethylamine (0.1 ml) was added to the solution. The mixture was stirred at room temperature for 2 hours. The solvent was removed under reduced pressure. Ethyl acetate (20 ml) was added to the residue. A solution of sodium bicarbonate 1% (w/w) was added to the mixture. The mixture was stirred at room temperature for 2 hours. The solid was collected by filtration. The organic layer was dried with anhydrous MgSO 4 . Ethyl acetate was removed under reduced pressure. The solids were put together. The compound was stirred in water for 1 hour and then collected by filtration and dried in a vacuum system (containing NaOH pellets) at room temperature: melting point: 300-301° C.; IR: 3212, 2842, 1738, 1698, 1516, 1401, 1373, 1343, 1238, 1177, 1140 cm −1 ;  1 H-NMR (DMSO d 6 ) δ (ppm) 1.95 (m, 2H), 2.70 (m, 4H), 2.80 (m, 4H), 3.15 (m, 4H), 6.90 (s, 4H), 7.40 (t, 1H), 7.50 (t, 2H), 7.50 (t, 2H), 7.55 (d, 2H), 7.70 (d, 2H), 7.75 (d, 2H), 11.70 (s, 2H).  
       Example 6  
     Preparation of  
     N-{ 4 -[4-(5-(1,1′-Biphenyl)-4-yl-2,4,6-trioxoperhydropyrimidin-5-yl)piperazin-1-yl]-phenyl)}acetamide  
       [0049]     Acetonitrile (1.2 ml) and acetic anhydride (1.2 ml) were added to 5-[1,1′-biphenyl]-4-yl-5-[4-(4-aminophenyl)piperazin-1-yl]pyrimidine-2,4,6(1H,3H,5H)-trione (70 mg). The mixture was stirred at room temperature for 30 minutes. The title compound was precipitated by addition of water (5 ml). The precipitate was collected by filtration and washed with water. The compound was dried in a vacuum system (containing P 2 O 5 ) at room temperature: melting point: 267-268° C.; IR: 3385, 2992, 2832, 1703, 1662, 1600, 1539, 1513, 1413, 1339, 1319, 1222 cm −1 .  
       Example 7  
     Preparation of  
     N-{4-[4-(5-(1,1′-Biphenyl)-4-yl-2,4,6-trioxoperhydropyrimidin-5-yl)-piperazin-1-yl]phenyl}formamide  
       [0050]     Formic acid (1 ml) was mixed with acetic anhydride (2 ml). The mixture was stirred at 50° C. for 30 minutes (solution A).  
         [0051]     Acetonitrile (1 ml) and solution A (1 ml) were added to 5-[1,1′-biphenyl]-4-yl-5-[4-(4-aminophenyl)piperazin-1-yl]pyrimidine-2,4,6(1H,3H,5H)-trione (70 mg). The mixture was stirred at room temperature for 30 minutes. The solvent was evaporated under reduced pressure. The residue was dissolved in hot methanol. The solution was treated with charcoal and then filtered. The product was precipitated by addition of water, collected by filtration and washed with water and dried: melting point: 270-271° C.; IR: 3061, 2836, 1737, 1706, 1518, 1402, 1334, 1314, 1235 cm − .  
         [0000]     Pharmacological Results  
         [0052]     Two pharmacological in vitro tests were carried out.  
         [0000]     1. Test on Isolated Enzymes  
         [0053]     The matrix metalloproteinase (MMP) inhibitory activity has been evaluated in a classical biochemical assay using fluorigenic peptide substrates. Briefly, a peptide bearing 1) a fluorescent group and 2) a quenching group bound to another amino acid of the peptide is submitted to the proteolytic action of an MMP. The cleavage of peptide bounds due to the MMP results in a dequenching of the fluorescent group. There is a direct relationship between the observed fluorescence and the activity of the enzyme. The MMP inhibiting activity of a given substance can then be assessed using this assay.  
         [0054]     The compounds of the present invention have been assayed using this assay design with recombinant human MMP2, MMP14 and MMP16 and the peptide ZGly-Gly-ArgAMC, which is a well-known, commercially available substrate of MMPs.  
         [0055]     The following IC 50  values (inhibitor concentration required to inhibit 50% of the enzyme) have been obtained with the compounds prepared according to examples 2 to 5 and compared to a product of the state of the art, better known as Ro 28-2653. Ro 28-2653 is included in claim 1 of WO 01/25217.  
                                                           TABLE 1                           IC 50  (nM) values on isolated enzymes            —NR 1 R 2     MMP-2   MMP-16   MMP-14   compound                    —NO 2     246   91   96   Ro 28-2653       —NH—CO—   110   39   29   example 2       (CH 2 ) 2 —COOH       —NH—CO—   98   49   26   example 3       (CH 2 ) 3 —COOH                                             75   21   13   example 4                                             93   20   23   example 5                  
 
         [0056]     Table I illustrates the improvement in MMP inhibitory activity of the compounds of the present invention compared to the compound of the state of the art Ro 28-2653.  
         [0000]     2. Test on Aorta Ring:  
         [0057]     Compound 5-(1,1′-biphenyl)-4-yl-5-{4-[4-(2,5-dioxopyrrolidin-1-yl)phenyl]piperazin-1-yl}pyrimidine-2,4,6(1H,3H,5H)-trione prepared according to example 4 has also been assayed in an aorta ring angiogenesis assay.  
         [0058]     Briefly, in the aorta ring assay, fresh slices (ring) of aorta dissected from rat were embedded in collagen1 and then cultivated in Petri dishes after addition of culture medium (n=6). After 6-9 days in control conditions, microscopic examination of the slices showed an outgrowth of capillary vessels from the edges of the explants. The effect of the compound of example 4 (10 μM) on angiogenesis was evaluated by its potency to stimulate or to inhibit the outgrowth of the capillary vessels when it was added to the culture medium (n=6). The results yielded by cultivating aorta explants with the compound in the medium clearly showed that the molecule has the ability to severely inhibit the capillary vessel outgrowth and, hence, acts as a potent anti-angiogenesis factor.