Patent Application
20050124648
The present invention relates to adenosine A3 receptor ligands of the general formula (I), within those preferably antagonists, as well as their salts, solvates and isomers, and the pharmaceutical compositions containing them, to the use of the compounds of the general formula (I), as well as their salts, solvates and isomers, to the preparation of the compounds of the general formula (I) and their salts, solvates and isomers, furthermore to the new intermediates of the general formulae (II) and to the preparation thereof.
Adenosine is a well-known component of several endogenous molecules (ATP, NAD+, nucleic acids). Besides, it plays an important regulatory role in many physiological processes. The effect of adenosine on heart function was discovered already in 1929 (Drury and Szentgyörgyi, J Physiol 68:213, 1929). The identification of an increasing number of physiological functions mediated by adenosine and the discovery of new adenosine receptor subtypes give possibilities for therapeutic application of specific ligands (Poulse, S. A. and Quinn, R. J. Bioorganic and Medicinal Chemistry 6:619, 1998).
To date, the receptors for adenosine have been classified into three main classes: A1, A2 and A3. The A1 subtype is partly responsible for inhibiting the adenylate cyclase by coupling to Gi membrane protein, partly influences other second messenger systems. The A2 receptor subtype can be subdivided into two further subtypes—A2a and A2b—, which receptors stimulate the adenylate cyclase activity. The sequence of adenosine A3 receptors has been recently identified from rat testis cDNA library. Later it was proved that it corresponds to a novel, functional adenosine receptor. The activation of the A3 receptors is connected also with several second-messenger systems: e.g. inhibiting of adenylate cyclase, and stimulating of phospholipase C and D.
The adenosine receptors are found in several organs and regulate their functions. Both A1 and A2a receptors play important roles in the central nervous system and cardiovascular system. In the CNS, the adenosine inhibits the release of synaptic transmitters which effect is mediated by A1 receptors. In the heart, also the A1 receptors mediate the negative inotropic, chronotropic and dromotropic effects of adenosine. The adenosine A2a receptors located relatively in a higher amount in the striatum, display a functional interaction with dopamine receptors in regulating the synaptic transmission. The A2a adenosine receptors on endothelial and smooth muscle cells are responsible for adenosine-induced vasodilation.
On the basis of mRNA identification, the A2b adenosine receptors are widely distributed in different tissues. They have been identified almost in every cell type, but its expression is the highest in the intestine and the bladder. This subtype probably also has important regulatory function in the regulation of the vascular tone and plays a role in the function of mast cells.
Contrary to A1 and A2a receptors, where the tissue distribution was detected on the protein level, the presence of A2b and A3 receptors was detected on the basis of their mRNA level. Expression levels for A3 adenosine receptors are rather low comparing to other subtypes and highly species dependent. A3 adenosine receptors are expressed primarily in the central nervous system, testis, immune system and appear to be involved in the modulation of mediator release from mast cells in immediate hypersensitivity reaction.
The A3 antagonists published so far in the literature belong to the groups of flavonoides, 1,4-dihydropyridine derivatives, triazoloquinazolines, thiazolonaphthyridines and thiazolopyrimidines. The present invention relates to a novel type of effective A3 antagonists, which have the triazolo-quinolin structure.
For therapeutic use it is essential to ensure that the molecule does not bind, or bind only in the case of very high concentration to the A1, A2a and A2b sub-types of the adenosine receptor. Our present invention relates to the compounds of the general formula (I) as well as their salts, solvates and isomers which have great selectivity for the A3 sub-type of the adenosine receptor.
Our aim was to prepare A3 ligands first of all with triazolo-quinolin structure, and within those preferably antagonists, which have strong antagonistic effect and show high selectivity for the A3 receptor, i.e. they inhibit the A3 receptor in much lower concentration than they inhibit the A1, A2a and A2b receptors. Further aims were to have stability, bioavailability, therapeutic index and toxicity data which make possible to develope the new compounds into drug substances and that due to their favourable enteral absorbtion the compounds can be applied orally.
We have found that the compounds of the general formula (I)—wherein
Detailed meanings of the above listed substituents are as follows:
By a straight or branched C1-4 alkyl group we mean methyl-, ethyl-, propyl-, isopropyl-, butyl-, isobutyl-, secondary-butyl-, terciary-butyl-, preferably ethyl- or methyl group.
By a straight or branched C1-4 alkoxy group we mean methoxy-, ethoxy-, propoxy-, isopropoxy-, butoxy-, isobutoxy-, secondary-butoxy-, terciary-butoxy-, preferably ethoxy- or methoxy group.
The heteroaromatic ring containing one or two or three nitrogen atoms means pyrrol, imidazole, pyrazole, 1,2,3-triazole, 1,2,4-triazole, pyridine, pyrimidine, pyridazine, pyrazine and 1,3,4-triazine ring. The ring is optionally substituted by a C1-4 alkyl group.
The heteroaromatic ring containing one nitrogen atom and one oxygen or sulphur atom means oxazole, isoxazole, thiazole, isothiazole ring. The ring is optionally substituted by a C1-4 alkyl group.
Salts of the compounds of the general formula (I) mean salts given with inorganic and organic acids and bases. Preferred salts are those given with pharmaceutically accepted acids as for instance hydrochloric acid, sulphuric acid, ethanesulphonic acid, tartaric acid, succinic acid, fumaric acid, malic acid, citric acid.
Solvates mean solvates given with various solvents, as for instance with water or ethanol.
The compounds of the general formula (I) show geometric and optical isomerism, therefore the invention also relates to mixtures of the geometric isomers, to racemic or optically active geometric isomers, as well as to their salts and solvates.
A favourable group of the compounds of the general formula (I) is formed by the compounds of the general formula (Ia), wherein
Especially favourable are the following compounds complying with the above criteria:
According to another of its aspects, the present invention also relates to pharmaceutical compositions containing as active principles the compounds of the general formula (I) or their isomers, salts and solvates, which are preferably oral compositions, but inhalable, parenteral and transdermal formulations are also subjects of the invention. The above pharmaceutical compositions may be solids or liquides, such as tablets, pellets, capsules, patches, solutions, suspensions or emulsions. The solid compositions, first of all tablets and capsules are the preferred pharmaceutical forms.
The above pharmaceutical compositions are prepared by applying usual pharmaceutical excipients and by using standard methods.
The compounds of the general formula (I) can be used in treating pathologies, in the development of which A3 receptor plays a role.
The compounds of the present invention having selective activity on the A3 receptor can be used in the therapeutic and/or preventive treatment of disfunctions of the heart, kidney, respiratory system, central nervous system. They inhibit the protective effect of adenosine in growing tumor cells, prevent mast cell degranulation, inhibit the cytokine production, reduce the inraocular pressure, inhibit the TNFα release, inhibit the migration of eosinophils, neutrophils and other immune cells, inhibit the bronchoconstriction and plasma extravasation.
Based on these effects, adenosine A3 receptor antagonists of the present invention may be therapeutically useful as antiinflammatory, antiasthmatic, antiischemic, antidepressant, antiarrhytmic, renal protective, antitumor, antiparkinson and cognitive enhancing drugs. They also may be useful in the treatment or prevention of miocardial reperfusion injury, chronic obstructive pulmonary disease (COPD) and adult respiratory distress syndrome (ARDS) including chronic bronchitis, pulmonary emphysema or dyspnea, allergic reactions (e.g. rhinitis, poison ivy induced responses, urticaria, scleroderma, arthritis) other autoimmune diseases, inflammatory bowel disease, Addison's disease, Crohn's disease, psoriasis, rheumatism, hypertension, neurogical function disorders, glaucoma and diabetes (K. N. Klotz, Naunyn-Schmiedberg's Arch. Pharmacol. 362:382, 2000; P. G. Baraldi és P. A. Borea, TiPS 21:456, 2000).
The compounds of the present invention may be preferable used for the treatment of diseases such as asthma, COPD and ARDS, glaucoma, tumor, allergic and inflammatory diseases, ischemia, hypoxia, arrythmia and renal diseases.
According to another of its aspects, the present invention relates to the use of the compounds of the general formula (I) in the treatment of the above pathologies. Suggested daily dose is 0,1-1000 mg active ingredient depending on the nature and severeness of the disease and on sex, weight etc. of the patient.
Further subject of the invention is the preparation of the compounds of the general formula (I) and of the intermediates of the general formulae (II), (I), and (IV).
The intermediates of the general formula (II) are novel. Substituents of the general formulae (II), (III), and (IV) have the meanings as defined above.
In the process according to our invention an 1,2-diamino-azinium salt of the general formula (II) is reacted with a compound of the general Formula (VII), wherein R7 is defined above and Y stands for hydrogen atom, halogen atom or a C1-4 alkoxy group, preferable with the suitable acid halogenide or ester (D. W. Robertson, J. Med. Chem., 28, 717, (1985)) and the compound of the general formula (I) thus obtained is, if desired, transformed into its salts, solvates or, liberated from its salt, solvate and separated into its geometric or optical isomers.
The ring closure can be carried out in the presence of triethylamine in dimethylformamide or of other compounds known as catalysts for ring closures similar type.
The ring closure can be carried out within wide temperature range, preferable within 20° C. and 150° C.
Substituents of the compounds of the general formula (I) may be transformed into each other by known methods.
The compounds of the general formula (II)—wherein the meanings of R1, R2, R3, R4, R5, R6, X and n are as defined above—can be obtained by several known methods, among them the one demonstrated in Scheme 1., by N-amination of the compounds of the formula (III), using N-amination processes known in the organic chemistry (E. E. Glover, R. T. Rowbotton, J. Chem. Soc. Perkin. Trans I., 376, (1976), G. Timári, Gy. Hajós, S. Bátori és A. Messmer, Chem. Ber., 125, 929 (1992)). For N-amination agent preferably O-tosyl-hydroxylamine can be applied, but other agents known for N-amination can also be used.
The compounds of the general formula (III)—wherein the meanings of R1, R2, R3, R4, R5, R6, X and n are as defined above—can be prepared from the compounds of the formula (IV)—by using methods known per se (Nan Zhang, Bioorg. and Med. Chem. Lett., 10, 2825, (2000)).
The compounds of the general formula (IV)—wherein the meanings of R4, R5, R6 are as defined above—can be prepared from the compounds of the formula (V), by using methods known per se (D. L. Leysen, J. Heterocyclic Chem., 24, 1611, (1987)).
The compounds of the general formula (V)—wherein the meanings of R4, R5, R6 are as defined above—can be prepared by using methods known per se (Pfizer (Inc) U.S. Pat. No. 4,175,193).
The compounds of the invention, of the general formulae (I), (II), (III) and (IV)), their preparation and biological activity are demonstrated in the following Examples, without limiting the scope of claims to the Examples.
In general formula (I) R1 and R2 stand for hydrogen atoms, R3 for phenyl group, R4 and R5 form together a 1,3-butadienyl group, R6 stands for cyano group, R7 stands for 4-methoxyphenyl group, the meaning of X is —NH group, n is 1.
The mixture of 10 g of 2-amino-3-cyano-4-hydroxyquinolin and 15 ml of phosphoryl chloride is heated under stirring at 110° C. The reaction mixture is cooled down, poured onto 100 ml of ice-water and neutralized with 60 ml of 10% sodium hydroxide solution. The resulting yellow precipitate is filtered off, washed with 50 ml of water. After drying 7.5 g of the title compound is obtained, mp.: 210° C.
NMR, δH (400 MHz, DMSO-d6): 7.21 ppm, (s, 2H, NH2), 7.35-7.40 ppm, (dd, 1H, 6-H), 7.53-7.57 ppm, (d, 1H, 5-H), 7.70-7.75 ppm, (dd, 1H, 7-H), 7.93-7.98 ppm, (d, 1H, 8-H)
5 g of 2-amino-3-cyano-4-chloroquinolin and 11 ml of benzylamine are heated under stirring at 130° C. The reaction mixture is poured onto 50 ml of water, the resulting precipitate is filtered off, washed with 50 ml of water. The pale-yellow precipitate is recrystallized from dimethylformamide to obtain 5.2 g of the title compound. Mp.: 206° C.
NMR, δH (400 MHz, DMSO-d6): 5.02-5.03 ppm, (d, 2H, N—CH2), 6.22 ppm, (s, 2H, NH2), 7.14-7.16 ppm, (dd, 1H, 6-H), 7.24-7.26 ppm, (dd, 1H, 5-H), 7.30 ppm, (s, 5H, Ph), 7.50-7.52 ppm, (dd, 1H, 7-H), 8.16-8.19 ppm, (d, 1H, 8-H), 8.30-8.33 ppm, (t, 1H, NH)
To the solution of 2.0 g of 2-amino-3-cyano-4-benzylaminoquinolin in 30 ml of dimethylformamide 1.78 g O-tozyl-hydroxylamine in 20 ml dichloromethane are dropped at 20° C. within 15 minutes. The reaction mixture is stirred for 5 hour, than the precipitate is filtered off. The resulting white crystalline material is recrystallized from acetonitrile to give 3.1 g of the title compound, mp.: 207° C.
To the mixture of 2.0 g. 1,2-diamino-3-cyano-4-benzylamino-quinolinium-tozylate and 15 ml pyridine 2 g of aniseacid chloride are added. The reaction mixture is stirred for 8 hour at 100° C. The mixture is poured onto 50 ml of water, the cristalls precipitated are filtered off and recrystallised from acetonitrile to give 1.1 g of the title compound. Mp.: 237C.
NMR, δH (400 MHz, DMSO-d6): 8.78 ppm (t,1H), 8.58 (d,1H), 8.38 (d,1H), 8.10 (d,2H), 7.98 (t,1H), 7.39 (m, 5H), 7.07 (d,2H), 5.14 (d,2H), 3.82 (s,3H).
In the general formula (1) the meaning of R1 and R2 is hydrogen atom, R3 is 2-furyl group, R4 and R5 form together an 1,3-butadienyl group, R6 stands for cyano group, R7 stands for 2-furyl group, X means —NH-group, n is 1.
5 g of 2-amino-3-cyano-4-chloroquinolin and 1 ml of furylmethylamine (furfurylamine) are heated under stirring at 130° C. The reaction mixture is poured onto 50 ml of water, the resulting precipitate is filtered off, washed with 50 ml of water. The pale-yellow precipitate is recrystallized from 20 ml ethanol to obtain 4.8 g of the title compound. Mp.: 208° C.
To the solution of 2.0 g of 2-amino-3-cyano-4-(2-furylmethylamino)-quinolin in 30 ml dimethylformamide 1.78 g O-tozyl-hydroxylamine in 20 ml dichloromethane are dropped at 20° C. within 15 minutes. The reaction mixture is stirred for 5 hour, than the precipitated white cristalline material is filtered off and recrystallized from acetonitrile to give 2.1 g of the title compound, mp.: 211° C.
To the mixture of 2.0 g. 1,2-diamino-3-cyano-4-(2-furylmethylamino)-quinolinium-tozylate and 15 ml pyridine 2 g of furan-2-carboxylic-acid-chloride are added. The reaction mixture is stirred for 8 hour at 100° C. The mixture is poured onto 50 ml of water, the cristalls precipitated are filtered off and recrystallised from acetonitrile to give 1.1 g of the title compound. Mp.: 203C.
NMR, δH (400 MHz, DMSO-d6): 8.74 ppm (t,1H), 8.52 (d,1H), 8.32 (d,1H), 7.90 (m,3H), 7.63 (m,2H), 7.14 (m,1H), 6.68 (m,1H), 6.44 (m,2H), 5.11 (d,2H).
In the general formula (1) the meaning of R1 and R2 is hydrogen atom, R3 is furyl group, R4 and R5 form together an 1,3-butadienyl group, R6 stands for cyano group, R7 stands for 3,4 methylendioxyphenyl group, X means —NH-group, n is 1.
To the mixture of 2.0 g. 1,2-diamino-3-cyano-4-(2-furylmethylamino)-quinolinium-tozylate and 15 ml pyridine 2 g of 3,4-methylendioxy-benzoic-acid-chloride are added. The reaction mixture is stirred for 8 hour at 100° C. The mixture is poured onto 50 ml of water, the cristalls precipitated are filtered off and recrystallised from acetonitrile to give 1.4 g of the title compound. Mp.: 185C.
NMR, δH (400 MHz, DMSO-d6): 8.55 ppm (m,1H), 8.51 (d,1H), 8.31 (d,1H), 7.93 (t,1H), 7.57-7.70 (m,3H), 7.05 (d,1H), 6.44 (m,2H), 6.11 (s,2H), 5.08 (d,2H).
In the general formula (I) the meaning of R1 and R2 is hydrogen atom, R3 is 2-tienyl group, R4 and R5 form together an 1,3-butadienyl group, R6 stands for cyano group, R7 stands for 3-pyridyl group, X means —NH-group, n is 1.
5 g of 2-amino-3-cyano-4-chloroquinolin and 11 ml of tienylmethylamine are heated under stirring at 130° C. The reaction mixture is poured onto 50 ml of water, the resulting precipitate is filtered off, washed with 50 ml of water. The pale-yellow precipitate is recrystallized from 25 ml ethanol to obtain 5.2 g of the title compound. Mp.: 208° C.
To the solution of 2.0 g of 2-amino-3-cyano-4-(2-tienylmethylamino)-quinolin in 30 ml dimethylformamide 1.78 g O-tozyl-hydroxylamine in 20 ml dichloromethane are dropped at 20° C. within 15 minutes. The reaction mixture is stirred for 5 hour, than the precipitated white cristalline material is filtered off and recrystallized from acetonitrile to give 2.1 g of the title compound, mp.: 198° C.
To the mixture of 2.0 g. 1,2-diamino-3-cyano-4-(2-tienylmethylamino)-quinolinium-tozylate and 20 ml dimethylformamide 4 ml of triethylamine and 4 g of pyridine-3-carboxaldehyde are added. The reaction mixture is stirred for 8 hour at 100° C. The mixture is poured onto 50 ml of water, the cristalls precipitated are filtered and recrystallised from acetonitrile to give 0.8 g of the title compound. Mp.: 249C.
NMR, δH (400 MHz, DMSO-d6): 9.25 ppm (s,1H), 8.71 (m,2H), 8.35 (m,3H), 7.86 (m,1H), 7.51 (m,3H), 7.17 (m,1H), 6.98 (m,1H), 5.25 (d,2H).
In the general formula (I) the meaning of R1 and R2 is hydrogen atom, R3 is 2-tienyl group, R4 and R5 form together an 1,3-butadienyl group, R6 stands for cyano group, R7 stands for 3-hydroxyphenyl group, X means —NH-group, n is 1.
To the mixture of 2.0 g. 1,2-diamino-3-cyano-4-(2-tienylmethylamino)-quinolinium-tozylate and 20 ml dimethylformamide 4 ml of triethylamine and 4 g of 3-hydroxy-benzaldehyde are added. The reaction mixture is stirred for 8 hour at 100° C. The mixture is poured onto 50 ml of water, the cristalls precipitated are filtered off and recrystallised from acetonitrile to give 0.9 g of the title compound. Mp.: 248C.
NMR, δH (400 MHz, DMSO-d6): 9.66 ppm (s,1H), 8.81 (m,1H), 8.52 (m,1H), 8.35 (m,1H), 796 (m,1H), 7.62 (m,3H), 7.44 (m,1H), 7.32 (m,1H), 7.18 (m,1H), 7.01 (m,1H), 6.88 (m,1H), 5.29 (d,2H);
Structure and physical characteristics of further compounds of general formula (I) prepared by the method described in Example 1 are shown in Table I.
Structure and physical characteristics of the intermediates of the general formula (III) prepared by the method described in Example 1. are shown in Table (II)
Structure and physical characteristics of the intermediates of the general formula (IV) prepared by the method described in Example 1. are shown in Table (III)
Tablets of the following composition are made by known methods used in the pharmaceutical industry
Biology
Methods
Human Adenosine A3 Receptor Binding
Preparing membrane suspension: collect CHO cells expressing hA3 receptors by washing three times with ice cold PBS; centrifugate at 1000×g 10 min, homegenize for 15 sec in buffer (50 mM Tris, 10 mM MgCl2, 1 mM EDTA, pH 8.0), centrifugate at 43.000×g for 10 min (Sigma 3K30), suspense the membrane preparation in the buffer mentioned above, store the aliquots at −80 C.
Binding protocol: incubate CHO-hA3 membrane preparation (2 μg protein content) in incubation buffer (50 mM Tris, 10 mM MgCl2, 1 mM EDTA, 3 U/mL adenosine deaminase, pH 8.0), in the presence of 0.5 nM [125I]AB-MECA (p-amino-benzyl-methylcarboxamido-adenosine) (100.000 cpm) and 100 μM R-PIA (N6-[L-2-phenylisopropyl]adenosine) to define non-specific binding or test compound in a total volume of 50 μL for 1 hr at room temperature. Filter over Whatman GF/B glass fibre filters (presoaked in 0.5% polyethylenimine for 3 hours), wash 4× with 1 mL ice-cold 50 mM Tris, 10 mM MgCl2, 1 mM EDTA (pH 8.0) on 96-well Brandel Cell Harvester. Detection of activity: in gamma-counter (1470 Wizard, Wallac). Inhibition [%]=100−((activity in the presence of test compound−non-specific activity)/(total activity−non-specific activity))*100
Human Adenosine A1 Receptor Binding
Preparing membrane suspension: collect CHO cells expressing hA1 receptors by washing three times with ice cold PBS, centrifugate at 1000×g 10 min, homogenize for 15 sec in buffer (50 mM Tris, pH 7.4), centrifugate at 43.000×g for 10 min (Sigma 3K30), suspense the membrane preparation in the buffer mentioned above, store the aliquots at −80 C.
Binding protocol: incubate CHO-hA1 membrane preparation (50 μg protein content) in incubation buffer (50 mM Tris, 3 U/mL adenosine deaminase, pH 7.4), 10 nM [3H]CCPA (2-chloro-N6-cyclopenthyl-adenosine) (80.000 dpm) and 10 μM R-PIA N6-[L-2-phenylisopropyl]adenosine) to define the non-specific binding or test compound in a total volume of 100 μL for 3 hr at room temperature. Filter over Whatmnan GF/B glass fibre filters (presoaked in 0.5% polyethylenimine for 3 hours), wash 4× with 1 mL ice-cold 50 mM Tris (pH 7.4) on 96-well Brandel Cell Harvester. Detection of activity: in 96-well plate in the presence of HiSafe-3 coctail in beta-counter (1450 Microbeta, Wallac). Inhibition [%]=100−((activity in the presence of test compound−non-specific activity)/(total activity−non-specific activity))*100
Human Adenosine A2a Receptor Binding
Binding protocol: incubate 7 μg of membranes (human A2a adenosine receptors transfected into HEK-293 cells, source: Receptor Biology, Inc.), buffer (50 mM Tris-HCl, 10 mM MgCl2, 1 mM EDTA, 2 U/mL adenosine deaminase, pH 7.4), 20 nM [3H]CGS-21680 (2-[p-(2-carbonylethyl)phenylethylamino]-5′-N-ethylcarboxamido-adenosine) (200.000 dpm) and 50 μM NECA (5′-N-ethylcarboxamido-adenosine) to define the non-specific binding or test compound in a total volume of 100 μl for 90 min at room temperature. Filter over Whatman GF/B glass fibre filters (presoaked in 0.5% polyethylenimine), wash 4× with 1 mL ice-cold 50 mM Tris, 10 mM MgCl2, 1 mM EDTA, 0.9% NaCl, pH 7.4) on 96-well Brandel Cell Harvester. Detection of activity: in 96-well plate in the presence of HiSafe-3 coctail in beta-counter (1450 Microbeta, Wallac). Inhibition [%]=100−((activity in the presence of test compound−non-specific activity)/(total activity−non-specific activity))*100
Human Adenosine A2b Receptor Binding
Binding protocol: incubate 20.8 μg of membranes (human A2b adenosine receptors transfected into HEK-293 cells, source: Receptor Biology, Inc.), buffer (50 mM Tris-HCl, 10 mM MgCl2, 1 mM EDTA, 0.1 mM benzamidine, 2 U/mL adenosine deaminase, pH 6.5), 32.4 nM [3H]DPCPX (8-cyclopenthyl-1,3-dipropylxanthine) (800.000 dpm) and 100 μM NECA (5′-N-ethylcarboxamido-adenosine) to define non-specific binding or test compound in a total volume of 100 μL for 30 min at room temperature. Filter over Whatman GF/C glass fibre filters (presoaked in 0.5% polyethylenimine), wash 4× with 1 mL ice-50 mM Tris-HCl (pH 6.5) on 96-well Brandel Cell Harvester. Detection of activity: in 96-well plate in the presence of HiSafe-3 coctail in beta-counter (1450 Microbeta, Wallac). Inhibition [%]=100−((activity in the presence of test compound−non-specific activity)/(total activity−non-specific activity))*100
Results
We consider the compounds as biologically active ones if they inhibit the binding of the radioligand on human adenosine A3 receptors with an activity above 80% at 1 μM in our experimental conditions.
The dissociation constant (Kd) of [125I]-MECA on CHO-hA3 membrane preparation is determined by isotope saturation-studies with the help of Scatchard analysis. (G. Scatchard, Ann. N.Y. Acad. Sci. 51:660, 1949). The IC50 is converted to an affinity constant (Ki) by application of the Cheng-Prusoff equation (Y. J. Cheng and W. H. Prusoff, Biochem. Pharmacol. 22:3099, 1973).
Several compounds of the general formula (I), (II), (III) and (IV) display remarkable biological effects. The compounds of the general formula (IA), defined in claim 2, as a subgroup of the general formula (I), defined in claim 1, exert the most important activities. Except of 9 compounds, their Ki values are not higher than 20 nM. The compounds given as examples are especially advantageous. Their Ki values in human adenosine A3 receptor binding studies are between 3.5 and 0.78 nM. The Ki values of the most advantageous compounds are 0.82 and 0.78 nM.
The compounds possess proper bioviabilities and exert at least 1,000-fold selectivity in respect of human adenosine A1, A2a and A2b receptor subtypes.
Further, the duration of their action at intravenous and oral administration is long enough, their ED50 values are low, their toxicological and side-effect profiles are advantageous.
Data above make the compounds of the general formula (I) probable for therapeutic applications.
| Number | Date | Country | Kind |
|---|---|---|---|
| P0105407 | Dec 2001 | HU | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/HU02/00143 | 12/17/2002 | WO |
