# Patent

## Title
Use of tetrahydropteridine derivatives as no synthase inhibitors

## Abstract

The present invention relates to the use of pteridine derivatives of the formula I 




in which X is O or NH and R4, for example, is hydrogen, phenyl or the radical R4a—CH2— and R4a, for example, is hydrogen, (C1-C4)-alkylmercapto, the radical —NR11R12 or the radical —OR13, and in which R1, R2, R3, R5, R6, R7, R11, R12 and R13 have the meanings given in claim 1, which are nitric oxide synthase inhibitors, for the treatment of diseases which are caused by an increased nitric oxide level.

## Background
This is a continuation of application Ser. No. 08/750,011, filed Nov. 21, 1996, abn. which is a U.S. National Phase Application of PCT/EP95/01785, filed May 11, 1995, all of which are incorporated herein by reference.


The present invention relates to pteridine derivatives of the formula I 




which on account of their ability to modulate endogenous nitric oxide production are useful pharmaceuticals for the prevention and control of states which are characterized by a disturbed nitric oxide level.

Nitric oxide (NO) plays an important part in all sorts of physiological processes (see, for example, R. Henning, Nachr. Chem. Tech. Lab. 41 (1993), 413; H. H. H. W. Schmidt et al., Biochim. Biophys. Acta 1178 (1993), 153).
It has, for example, a relaxing effect on the smooth vascular musculature and in this way is substantially involved in the regulation of blood pressure. It controls blood clotting via inhibition of platelet aggregation, and it is involved, for example, as a neurotransmitter in the brain in the building up of long-term memory. NO also functions as a messenger substance in the NANC nerves of the peripheral nervous system. The cytotoxic action of NO is utilized by macrophages for defense against infection.
Endogenous NO is formed from arginine with the aid of at least three different NO synthase isoenzymes (see, for example, J. F. Kerwin, Jr., M. Heller, Med. Res. Rev. 14 (1994), 23). They differ with respect to their localization in the body, their regulability by Ca2+/calmodulin and their inducibility by endotoxins and cytokines. The constitutive, calcium-dependent NO synthases are found, for example, in endothelium (Type III) and in the brain (Type I) and are involved there in the regulation of blood pressure and coagulation and in the conduction process. The cytokine-inducible, calcium-independent isoform (Type II) occurs in macrophages, smooth muscle cells and hepatocytes. It is able, over the long term, to produce relatively large amounts of NO and is held responsible for inflammatory processes and the cytotoxic activity of the macrophages.
A disturbed NO balance results in serious disorders and damage. Thus excessive formation of NO in septic or hemorrhagic shock leads to massive pathological blood pressure decreases. Excess NO production is involved in the formation of type I diabetes and atherosclerosis and also appears to be responsible for glutamate-induced neurotoxicity after cerebral ischemia. High NO concentrations can moreover lead to DNA damage as a result of deamination of cytosine. Examples of disorders which are caused indirectly or directly by a lack of endogenous NO are arterial high blood pressure, hemostasis disorders, coronary heart disease and erectile dysfunction.
The attempt to use modulation of NO production for the treatment of these syndromes has until now only been realized with the aid of arginine analogs (GB-A-2240041; WO-A-93/13055). Further potential NO synthase inhibitors discussed in the literature are N-iminoethylornithine (McCall et al., Br.J.Pharmacol. 102 (1991), 234), amino-guanidine (T. P. Misko et al., Eur.J.Pharmacol. 233 (1993), 119; EP-A-547588) and 7-nitroindazole (P. K. Moore et al., Br.J.Pharmacol. 108 (1993), 296).
Various pteridine derivatives occur in nature, and uses of pteridine derivatives as pharmaceutical active compounds have also been described. Thus EP-B-108 890 relates to the use of pteridine derivatives for the treatment of diseases which can be attributed to a catecholamine deficiency, such as, for example, Parkinson's disease, and the use of pteridines for the treatment of phenylketonuria (see also E. C. Bigham et al., Chemistry and Biology of Pteridines (1986) S.111, Walter de Gruyter & Co., Berlin, N.Y.); these also include certain compounds of the formula I in which X is oxygen and R1, R2, R3 and R7 are simultaneously hydrogen. The action of the naturally occurring 5,6,7,8-tetrahydrobiopterin and of analogs of this substance on NO production was studied, for example, by Kwon et al. (J.Biol.Chem. 264 (1989), 20496) or Giovanelli et al. (Proc.Natl.Acad.Sci. USA 88 (1991), 7091). Accordingly, tetrahydrobiopterin stimulates NO production and is a cofactor of NO synthases. Stimulation of NO production was also found for 7,8-dihydrobiopterin. According to Overfeld et al. (Br.J.Pharmacol. 107 (1992), 1008), 5,6,7,8-tetrahydrobiopterin, however, can also have an inhibitory effect on NO production. The effect is concentration-dependent.
Hevel and Marletta (Biochemistry 31 (1992), 7160) reports on an increase in NO synthase activity due to 6-methyl-5,6,7,8-tetrahydropterin. This was only observed at relatively high concentrations by Giovanelli et al. (loc. cit.). Various other petals derivatives showed no significant effects in these studies.
Surprisingly, it has now been found that pteridine derivatives of the formula I, in particular, have an inhibiting modulatory effect on endogenous NO production and are thus suitable as pharmaceuticals in diseases which are characterized by an excessive NO level.
The present invention relates to the use of pteridine derivatives of the formula I 




in which

    
    
        X is O or NH;
        R1 is hydrogen, methyl, (C1-C5)-alkanoyl, nicotinoyl or (1-methyl-3-pyridinio)carbonyl;
        R2 is hydrogen or methyl;
        R3 is hydrogen, methyl, ethyl, benzyl, (C1-C5)-alkanoyl, unsubstituted benzoyl, substituted benzoyl, pyridoyl, thienylcarbonyl, one of the radicals 




         the radical R9R9aN—CO—, the radical R9R9aN—CS—, phenoxycarbonyl or benzyloxycarbonyl;
        R4 is hydrogen, (C2-C5)-alkyl, unsubstituted phenyl, substituted phenyl or the radical R4a—CH2—;
        R4a is hydrogen, (C1-C4)-alkylmercapto, the radial —S(O)mR10, where m is the numbers 1 or 2, the radical NR11R12 or the radical —OR13, or
        R3 and R4a together are the group —CO—O—, its carbonyl carbon atom being bonded to the 5-position of the pteridine molecule;
        R5 is hydrogen, methyl or phenyl;
        R6 is hydrogen or methyl;
        R7 is hydrogen or methyl;
        R8 is (C1-C10)-alkyl or benzyl;
        R9 is hydrogen, (C1-C6)-alkyl, cyclohexyl, phenyl or benzoyl;
        R9a is hydrogen, methyl or ethyl;
        R10 is methyl;
        R11 and R12 independently of one another are hydrogen or methyl;
        R13 is hydrogen, (C1-C10)-alkyl, 2-methoxyethyl, phenyl, 3-phenylpropyl, 3-cyclohexylpropyl, (C1-C5)-alkanoyl, hydroxyacetyl, 2-amino-(C2-C6)-alkanoyl which is unsubstituted or substituted in the alkyl moiety by a phenyl radical, or ((C1-C2)-alkoxy)carbonyl;
        A⊖ is a pharmacologically tolerable anion;

and their tautomeric forms and their pharmacologically tolerable salts for the prevention and treatment of diseases which are caused by an increased nitric oxide level.

    
    


Alkyl groups can be straight-chain or branched. This also applies if they occur in other groups, for example in alkoxy, alkylmercapto, alkoxycarbonyl or alkanoyl groups. Examples of alkyl groups which can occur in the compounds of the formula I to be used according to the invention as such, i.e. as (C1-C4-, (C2-C5)-, (C1-C6)- or (C1-C10)-alkyl, or in other groups, are methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, tert-butyl, n-pentyl, 3-methylbutyl, 2,2-dimethylpropyl, n-hexyl, n-heptyl, n-octyl, n-nonyl or n-decyl. Examples especially of (C1-C5)-alkanoyl are formyl, acetyl, propionyl, n-butyryl, i-butyryl, n-valeroyl, 3-methyl-n-butyryl or 2,2-dimethylpropionyl. Examples of (C1-C2)-alkoxy are methoxy and ethoxy. Examples of 2-amino-(C2-C6)-alkanoyl which is unsubstituted or substituted in the alkyl moiety by a phenyl radical are the corresponding radicals of the amino acids glycine, alanine, valine, leucine, isoleucine, norvaline, norleucine, phenylglycine or phenylalanine.
Substituted phenyl groups and benzoyl groups can be mono- or polysubstituted, preferably they are mono- to trisubstituted. The substituents can be located in any desired positions, an individual substituent, for example, in the ortho-, meta- or para-position. In the case of multiple substitution, the substituents can be identical or different. Substituents which can be present, for example, are (C1-C4)-alkyl, (C1-C4)-alkoxy, amino, (C1-C4)-alkylamino, di-((C1-C4)-alkyl)amino, (C1-C5)-alkanoylamino, nitro or halogen, where only up to two nitro groups can be present. Halogen is, for example, fluorine, chlorine, bromine or iodine.
Pyridoyl can be 2-, 3- or 4-pyridoyl, 3-pyridoyl (=nicotinoyl) being preferred. Thienylcarbonyl can be 2- or 3-thienylcarbonyl.
Examples of acids of the formula HA whose anion can be present in the compounds of the formula I to be used according to the invention are hydrochloric acid, hydrobromic acid, hydriodic acid, sulfuric acid, phosphoric acid, nitric acid, methanesulfonic acid, toluenesulfonic acid, acetic acid, propionic acid, benzoic acid, lactic acid, tartaric acid, citric acid, maleic acid and fumaric acid. A⊖, however, can also be an anion of another inorganic or organic acid which is suitable from pharmacological and pharmaceutical points of view and can, if the compound of the formula I is present in the form of an acid addition salt, correspond to the anion introduced by this salt formation or differ therefrom.
The compounds of the formula I can be present in various tautomeric forms and in various stereoisomeric forms. The present invention comprises not only the use of all tautomeric forms, but also that of all stereoisomeric forms, i.e., for example, that of pure enantiomers, of enantiomer mixtures and racemates, of pure diastereomers and diastereomer mixtures or of cis/trans isomers.
X is preferably oxygen.
Preferably, R1 and R2 are simultaneously hydrogen or simultaneously methyl, or R2 is hydrogen and R1 is simultaneously (C1-C5)-alkanoyl, in particular acetyl, i-butyryl or pivaloyl, or nicotinoyl or (1-methyl-3-pyridinio)carbonyl. Particularly preferably, R1 and R2 are simultaneously hydrogen or R2 is hydrogen and R1 is simultaneously i-butyryl.
R3 is preferably hydrogen or an acyl radical or a (thio)carbamoyl radical. Acyl radicals are in this case preferably understood as meaning (C1-C5)-alkanoyl, in particular formyl, acetyl and pivaloyl, unsubstituted or mono-, di- or trisubstituted benzoyl, thienylcarbonyl, as well as nicotinoyl and the radicals 




where R8 is preferably methyl, n-octyl or benzyl and preferred substituents in substituted benzoyl groups are halogen and methoxy. In the carbamoyl radicals R9R9aN—CO—, R9 is preferably hydrogen, (C1-C4)-alkyl, in particular tert-butyl, as well as cyclohexyl and phenyl and R9a is simultaneously hydrogen, or R9 and R9a are simultaneously methyl. In the thiocarbamoyl radicals R9R9aN—CS—, R9 is preferably hydrogen, (C1-C4)-alkyl, in particular methyl or ethyl, as well as phenyl and benzoyl and R9a is simultaneously hydrogen. Particularly preferably, R3 is hydrogen, the N-phenylthiocarbamoyl radical, the unsubstituted benzoyl radical, the niclotinoyl radical or a 3-pyridinocarbonyl radical derived from the latter by alkylation or benzylation on the nicotinoyl nitrogen or a 1,4-dihydro-3-pyridylcarbonyl radical alkylated or benzylated in the 1-position of the pyridine ring.

R4 is preferably hydrogen, phenyl, phenyl substituted by an acetylamino group, in particular by a para-acetylamino group, or the radical R4a—CH2—.
R4a is preferably hydrogen or the radical —OR13. If R4 is hydrogen or R4a is hydrogen, it is particularly preferred if R3 is simultaneously an acyl radical or a (thio)carbamoyl radical.
R5 is preferably hydrogen.
R7 is preferably hydrogen.
R9a is preferably hydrogen.
R13 is preferably hydrogen, (C1-C10)-alkyl or an acyl radical, in particular (C1-C5)-alkanoyl or 2-amino-(C2-C6)-alkanoyl which is unsubstituted or substituted in the alkyl moiety by a phenyl radical. Particularly preferably, R13 is C1-C10)-alkyl or (C1-C5)-alkanoyl, especially acetyl. If R13 is (C1-C10)-alkyl, n-alkyl radicals as well as i-propyl, i-butyl and tert-butyl are preferred.
Use of compounds of the formula I is preferred in which one or more substituents have preferred meanings. Use of pteridine derivatives of the formula Ia is furthermore preferred 




in which

    
    
        X is O or NH;
        R1 is hydrogen, methyl, (C1-C5)-alkanoyl, nicotinoyl or (1-methyl-3-pyridinio)carbonyl;
        R2 is hydrogen or methyl;
        R3 is hydrogen, methyl, ethyl, benzyl, (C1-C5)-alkanoyl, benzoyl, nicotinoyl, one of the radicals 




         the radical R9NH—CO—, the radical R9NH—CS— or benzyloxycarbonyl;
        R4a is hydrogen, (C1-C4)-alkylmercapto, the radical —S(O)mR10, where m is the numbers 1 or 2, the radical —NR11R12 or the radical —OR13, or
        R3 and R4a together are the group —CO—O—, its carbonyl carbon atom being bonded to the 5-position of the pteridine molecule;
        R5 and R6 independently of one another are hydrogen or methyl;
        R7 is hydrogen or methyl;
        R8 is (C1-C10)-alkyl or benzyl;
        R9 is hydrogen, (C1-C6)-alkyl, cyclohexyl, phenyl or benzoyl;
        R10 is methyl;
        R11 and R12 independently of one another are hydrogen or methyl;
        R13 is hydrogen, (C1-C10)-alkyl, 2-methoxyethyl, phenyl, 3-phenylpropyl, 3-cyclohexylpropyl, (C1-C5)-alkanoyl, hydroxyacetyl, 2-amino-(C2-C6)-alkanoyl which is unsubstituted or substituted in the alkyl moiety by a phenyl radical, or ((C1-C2)-alkoxy)carbonyl;
        A⊖ is a pharmacologically tolerable anion;

and their tautomeric forms and also their pharmacologically tolerable salts for the prevention and treatment of diseases which are caused by an increased nitric oxide level.

    
    


Particularly preferred compounds of the formula I to be used according to the invention are those in which R1, R2, R3, R5, R6 and R7 simultaneously are hydrogen and R4 is the radical R4a—CH2— and, in this, R4a is an amino group, a methylamino group, a dimethylamino group, a (C1-C10)-alkyloxy group or an acetoxy group. Compounds particularly preferably to be used are furthermore those in which R2, R4, R5, R6 and R7 are simultaneously hydrogen, R1 is hydrogen or isobutyryl and R3 is an acyl radical or a (thio)carbamoyl radical. A further group of compounds of the formula I particularly preferably to be used are those in which R2, R6 and R7 are simultaneously hydrogen, R1 is hydrogen or isobutyryl, R3 is an acyl radical, R4 is phenyl or phenyl substituted by an acetylamino group, in particular a para-acetylamino group, and R5 is hydrogen or phenyl.
The compounds of the formula I are known and can be prepared according to or analogously to known processes. Known synthesis methods for pteridine derivatives of the formula I are, for example, the method of Gabriel-Isay or the Taylor method (see, for example, D. J. Brown, Fused Pyrimidines III, Pteridines (E. C. Taylor and A. Weissberger (Ed.), Wiley & Sons, New York)). In detail, the preparation of compounds of the formula I is described, for example, in EP-A-108 890, in the thesis of Hermann Michael Traub (Dissertation der Universität Konstanz, Deutschland (1987)), or in J. Med. Chem. 30 (1987), 40.
The compounds of the formula I to be used according to the invention can form salts with inorganic or organic acids. Suitable acids for the formation of pharmacologically acceptable acid addition salts are, for example: hydrochloric acid, hydrobromic acid, naphthalenedisulfonic acids, in particular 1,5-naphthalenedisulfonic acid, or phosphoric, nitric, sulfuric, oxalic, lactic, tartaric, acetic, salicylic, benzoic, formic, propionic, pivalic, diethylacetic, malonic, succinic, pimelic, fumaric, maleic, malic, sulfamic, phenylpropionic, gluconic, ascorbic, isonicotinic, methanesulfonic, p-toluenesulfonic, citric or adipic acid. The compounds of the formula I can add one or more, e.g. two or three, in particular two, acid equivalents. The acid addition salts can be prepared in the customary manner by combination of the components, expediently in a suitable solzent or diluent. Acid addition salts can be converted into one another by anion exchange. A⊖ can likewise be an anion of one of the acids mentioned. Compounds of the formula I which can contain acidic groups can form salts with inorganic or organic bases. Examples of such salts are, for example, alkali metal salts, in particular sodium and potassium salts, or ammonium salts, in particular those with organic radicals on the ammonium nitrogen.
The inhibition of NO release by the compounds of the formula I can be determined by an activity assay based on the studies of Bredt and Snyder and also Schmidt et al. (see D. S. Bredt and S. S. Snyder, Isolation of nitric oxide synthase, a calmodulin-requiring enzyme, Proc. Natl. Acad. Sci. USA 87 (1990), 682; H. H. H. W. Schmidt et al., Purification of a soluble isoform of guanylyl cyclase-activating factor synthase, Proc. Natl. Acad. Sci. USA 88 (1991), 365). In this assay for purified NO synthase (NOS) the coproduct L-citrulline obtained during NO formation is determined quantitatively. This is carried out by the use of 3H-radiolabelled L-arginine as a substrate of the enzyme reaction, which is reacted to give 3H-L-citrulline and NO. After the enzyme incubation is complete, resulting L-citrulline is removed from unused L-arginine by means of ion-exchange chromatography of the reaction mixture; the 3H-activity determined by liquid scintillation measurement then corresponds to the amount of L-citrulline. Details of the procedure are given further below.
Diseases which arise due to an increased NO level and which can thus be treated according to the invention with the compounds of the formula I or which can be prevented using these, are, in particular, pathological blood pressure decreases, such as occur in septic or hemorrhagic shock, in tumor or cancer therapy with cytokines or in cirrhosis of the liver. In addition, inflammatory disorders, such as rheumatoid arthritis and in particular ulcerative colitis, as well as insulin-dependent diabetes mellitus and transplant rejection reactions.
However, the following disorders are also connected with increased production of nitric oxide and can be treated or prevented according to the invention. In the cardiovascular field, these are arteriosclerosis, post-ischemic tissue damage and infarct damage, reperfusion damage, myocarditis based on a Coxsackie virus infection and cardiomyopathy; in the nervous system/central nervous system field they are neuritides of varying etiogeneses (forms of neuritis), encephalomyelitides, viral neurodegenerative disorders, Alzheimer's disease, hyperalgesia, epilepsy andmigraine; in the kidney field they are acute kidney failure and nephritides of varying etiogeneses, especially glomerulonephritis.
Additionally, treatments in the stomach and the uterus/placenta field and also affecting sperm motility are also fields of use for the compounds of the formula I.
The compounds of the formula I and their pharmacologically acceptable salts can be employed in research and in diagnostic processes as auxiliaries in biochemical and pharmacological studies, and they can be administered to animals, preferably to mammals, and in particular to humans as therapeutics per se, as mixtures with one another or in the form of pharmaceutical preparations which allow enteral or parenteral use and which as active constituent contain an effective dose of at least one compound of the formula I or a salt thereof, in addition to customary pharmaceutically innocuous excipients and additives.
The therapeutics can be administered orally, e.g. in the form of pills, tablets, lacquered tablets, coated tablets, hard and soft gelatin capsules, solutions, syprups, emulsions or suspensions or aerosol mixtures. Administration, however, can also be carried out rectally, e.g. in the form of suppositories, or parenterally, e.g. in the form of injection solutions or infusion solutions, or percutaneously, e.g. in the form of ointments or tinctures.
In addition to the active compounds and excipients, the pharmaceutical preparations can also contain additives, such as, for example, fillers, extenders, disintegrants, binders, glidants, wetting agents, stabilizers, emulsifiers, preservatives, sweetening agents, colorants, flavorings or aromatizers, buffer substances, and further solvents or solubilizers or agents for achieving a depot effect, as well as salts for changing the osmotic pressure, coating agents or antioxidants. They can also contain two or more compounds of the formula I or their pharmacologically acceptable salts and also other therapeutically active substances.
Other therapeutically active substances of this type are, for example: β-receptor blockers, such as, for example, propranolol, pindolol, metoprolol; vasodilators, such as, for example, carbocromene; tranquillizers, such as, for example, barbituric acid derivatives, 1,4-benzodiazepines and meprobamate; diuretics, such as, for example, chlorothiazide; cardiotonic agents, such as, for example, digitalis preparations; hypotensive agents, such as, for example, hydralazine, dihydralazine, ramipril, prazosin, clonidine, Rauwolfia alkaloids; agents which lower the fatty acid level in the blood, such as, for example, bezafibrate, fenofibrate; agents for thrombosis prophylaxis, such as, for example, phenprocoumon; anti-inflammatory substances, such as, for example, cortico-steroids, salicylates or propionic acid derivatives, such as, for example, ibuprofen; antibiotics, such as, for example, penicillins or cephalosporins; NO donors, such as, for example, organic nitrates or sydnone imines or furoxanes.
The dose can vary within wide limits and is to be suited to the individual conditions in each individual case. In general, a daily dose of approximately 0.5 to 100 mg; preferably 1 to 20 mg, per human individual is appropriate in the case of oral administration. In the case of other administration forms too, the daily dose is in similar ranges of amounts, i.e. in general likewise at 0.5 to 100 mg/person. The daily dose can be divided into several, e.g. 2 to 4, part administrations.
To prepare the pharmaceutical preparations, pharmaceutically inert inorganic or organic excipients can be used. To prepare pills, tablets, coated tablets and hard gelatin capsules, for example, lactose, corn starch or derivatives thereof, talc, stearic acid or its salts, etc. can be used. Excipients for soft gelatin capsules and suppositories are, for example, fats, waxes, semi-solid and liquid polyols, natural or hardened oils etc. Suitable excipients for the production of solutions and syrups are, for example, water, sucrose, invert sugar, glucose, polyols etc. Suitable excipients for the production of injection solutions are, for example, water, alcohols, glycerol, polyols or vegetable oils.
Until now, no pharmacological effects or medicinal uses were known for various pteridine derivatives of the formula I. For such compounds, the present invention gives the first medicinal indication. The present invention also relates to pteridine derivatives of the formula I 




in which

    
    
        X is O or NH;
        R1 is hydrogen, methyl, (C1-C5)-alkanoyl, nicotinoyl or (1-methyl-3-pyridinio)carbonyl;
        R2 is hydrogen or methyl;
        R3 is hydrogen, methyl, ethyl, benzyl, (C1-C5)-alkanoyl, unsubstituted benzoyl, substituted benzoyl, pyridoyl, thienylcarbonyl, one of the radicals 




         the radical R9R9aN—CO—, the radical R9R9aN—CS—, phenoxycarbonyl or benzyloxycarbonyl;
        R4 is hydrogen, (C2-C5)-alkyl, unsubstituted phenyl, substituted phenyl or the radical R4a—CH2—;
        R4a is hydrogen (C1-C4)-alkylmercapto, the radical —S(O)mR10, where m is the numbers 1 or 2, the radical —NR11R12 or the radical —OR13 or
        R3 and R4a together are the group —CO—O—, its carbonyl carbon atom being bonded to the 5-position of the pteridine molecule;
        R5 is hydrogen, methyl or phenyl;
        R6 is hydrogen or methyl;
        R7 is hydrogen or methyl;
        R8 is (C1-C10)-alkyl or benzyl;
        R9 is hydrogen, (C1-C6)-alkyl, cyclohexyl, phenyl or benzoyl;
        R9a is hydrogen, methyl or ethyl;
        R10 is methyl;
        R11 and R12 independently of one another are hydrogen or methyl;
        R13 is hydrogen, (C1-C10)-alkyl, 2-methoxyethyl, phenyl, 3-phenylpropyl, 3-cyclohexylpropyl, (C1-C5)-alkanoyl, hydroxyacetyl, 2-amino-(C2-C6)-alkanoyl which is unsubstituted or substituted in the alkyl moiety by a phenyl radical, or ((C1-C2)-alkoxy)carbonyl;
        A⊖ is a pharmacologically tolerable anion;

and their tautomeric forms and also their pharmacologically tolerable salts where, however, if X is oxygen and at the same time R4 is the radical R4a—CH2—, at least one of the substituents R1, R2, R3 and R7 has a meaning other than hydrogen, as pharmacological active compounds.

    
    


The following examples give compounds of the formula I which can be employed according to the invention. In the column “salts” is indicated how many moles of acid and how many moles of water of crystallization, if appropriate, were present per mole of active compound in the pteridine derivatives of the formula I. In the examples, the following abbreviations are used:

    
    
        Me=methyl
        Et=ethyl
        iPr=isopropyl
        iBu=isobutyl
        tBu=tert-butyl
        Ph=phenyl
        Py=3-pyridyl 




    
    




EXAMPLE 1


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=H
        R7=H
        R3=H
        R4=Me
    
    


EXAMPLE 2


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=Me
        R3=H
        R4=Me
    
    


EXAMPLE 3


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=Me
        R3=CHO
        R4=Me
    
    


EXAMPLE 4


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=H
        R7=Me
        R3=CHO
        R4=Me
    
    


EXAMPLE 5


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=H
        R7=H
        R3=CONH2 
        R4=Me
        Salt: 0.5H2O
        m.p. 257° C.
    
    


EXAMPLE 6


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=H
        R7=H
        R3=CSNHMe
        R4=Me
        Salt: 1.5H2O
        m.p. 195° C.
    
    


EXAMPLE 7


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=H
        R7=H
        R3=CSNHPh
        R4=Me
        Salt: 2H2O
        m.p. 239° C.
    
    


EXAMPLE 8


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=H
        R7=H
        R3=CSNHEt
        R4=Me
        Salt: 2H2O
        m.p. 202° C.
    
    


EXAMPLE 9


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=H
        R7=H
        R3=CSNHCOPh
        R4=Me
        Salt: 0.5 H2O
        m.p. 229° C.
    
    


EXAMPLE 10


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=H
        R7=H
        R3=CONHPh
        R4=Me
        Salt: 1H2O
        m.p. 197° C. (dec.)
    
    


EXAMPLE 11


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=H
        R7=H
        R3=CONHtBu
        R4=Me
        Salt: 1H2O
        m.p. 260° C. (dec.)
    
    


EXAMPLE 12


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=H
        R7=H
        R3=CONH-cyclohexyl
        R4=Me
        Salt: 1H2O
        m.p. 242° C.
    
    


EXAMPLE 13


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=H
        R7=H
        R3=COPh
        R4=Me
        m.p. >320° C.
    
    


EXAMPLE 14


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=H
        R7=H
        R3=COPy
        R4=Me
        m.p. 295° C.
    
    


EXAMPLE 15


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=H
        R7=H
        R3=Ra 
        R4=Me
        Salt: 0.5H2O
        m.p. 275° C.
    
    


EXAMPLE 16


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=H
        R7=H
        R3=Rb 
        R4=Me
        m.p. 255° C.
    
    


EXAMPLE 17


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=Rb 
        R4=Me
        Salt: 1H2O
        m.p. 232° C.
    
    


EXAMPLE 18


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=H
        R7=H
        R3=Rc 
        R4=Me
        Salt: 0.5H2O
        m.p. 180° C.
    
    


EXAMPLE 19


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=COPy
        R4=Me
        Salt: 1H2O
        m.p. 265-270° C.
    
    


EXAMPLE 20


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=Rc 
        R4=Me
        m.p. 206-208° C.
    
    


EXAMPLE 21


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=H
        R7=H
        R3=Rd 
        R4=Me
        m.p. <200° C. (dec.)
    
    


EXAMPLE 22


    
    
        X=O
        R1=COiPr
        R2=H
        R5=Me
        R6=H
        R7=H
        R3=COPy
        R4=Me
        m.p. >300° C.
    
    


EXAMPLE 23


    
    
        X=O
        R1=COPy
        R2=H
        R5=Me
        R6=H
        R7=H
        R3=COPy
        R4=Me
        m.p. 325° C.
    
    


EXAMPLE 24


    
    
        X=O
        R1=Me
        R2=Me
        R5=Me
        R6=H
        R7=H
        R3=H
        R4=Me
        Salt: 2HCl
        m.p. >300° C.
    
    


EXAMPLE 25


    
    
        X=O
        R1=Me
        R2=Me
        R5=Me
        R6=H
        R7=H
        R3=COPy
        R4=Me
        m.p. 315° C. (dec.)
    
    


EXAMPLE 26


    
    
        X=O
        R1=Me
        R2=Me
        R5=Me
        R6=H
        R7=H
        R3=Re 
        R4=Me
        m.p. 238-240° C.
    
    


EXAMPLE 27


    
    
        X=O
        R1=Me
        R2=Me
        R5=Me
        R6=H
        R7=H
        R3=Ra 
        R4=Me
        Salt: 0.5H2O
        m.p. 271° C.
    
    


EXAMPLE 28


    
    
        X=O
        R1=Re 
        R2=H
        R5=Me
        R6=H
        R7=H
        R3=Re 
        R4=Me
        m.p. >250° C. (dec.)
    
    


EXAMPLE 29


    
    
        X=O
        R1=COiPr
        R2=H
        R5=Me
        R6=H
        R7=H
        R3=Ra 
        R4=Me
        Salt: 0.5H2O
        m.p. 251° C.
    
    


EXAMPLE 30


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2OH
        Salt: 2HCl+0.5H2O
        m.p. 238-240° C. (dec.)
    
    


EXAMPLE 31


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=COPh
        R4=CH2OH
        m.p. 246° C. (dec.)
    
    


EXAMPLE 32


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=Me
        R3=H
        R4=CH2OH
    
    


EXAMPLE 33


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=Me
        R3=CHO
        R4=CH2OH
    
    


EXAMPLE 34


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=Me
        R3=COMe
        R4=CH2OH
    
    


EXAMPLE 35


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2OMe
        Salt6: 2HCl
        m.p. 170° C. (dec.)
    
    


EXAMPLE 36


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2OEt
        Salt: 2HCl
        m.p. 165° C. (dec.)
    
    


EXAMPLE 37


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2OiPr
        Salt: 2HCl
        m.p. 219-221° C. (dec.)
    
    


EXAMPLE 38


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2OiBu
        Salt: 2HCl+0.5H2O
        m.p. 232-234° C. (dec.)
    
    


EXAMPLE 39


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2O-n-butyl
    
    


EXAMPLE 40


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2OtBu
    
    


EXAMPLE 41


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2O-n-pentyl
    
    


EXAMPLE 42


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2O-n-octyl
    
    


EXAMPLE 43


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2O-n-decyl
        Salt: 2HCl
        m.p. 180° C.
    
    


EXAMPLE 44


    
    
        X=O R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2OCH2CH2OMe
        Salt: 2HCl
        m.p. 221-222° C.
    
    


EXAMPLE 45


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2OPh
        Salt: 2HCl+0.25H2O
        m.p. 254-256° C. (dec.)
    
    


EXAMPLE 46


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=Me
        R7=H
        R3=H
        R4=CH2OH
    
    


EXAMPLE 47


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=Me
        R7=H
        R3=H
        R4=CH2OMe
    
    


EXAMPLE 48


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=Me
        R7=H
        R3=H
        R4=CH2OEt
    
    


EXAMPLE 49


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=Me
        R7=H
        R3=H
        R4=CH2O-n-propyl
    
    


EXAMPLE 50


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=Me
        R7=H
        R3=H
        R4=CH2OiPr
    
    


EXAMPLE 51


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=Me
        R7=H
        R3=H
        R4=CH2O-n-pentyl
    
    


EXAMPLE 52


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=Me
        R7=H
        R3=H
        R4=CH2O-n-octyl
    
    


EXAMPLE 53


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=Me
        R7=H
        R3=H
        R4=CH2O—CH2CH2CH(CH3)2 
    
    


EXAMPLE 54


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=Me
        R7=H
        R3=H
        R4=CH2O—(CH2)3Ph
    
    


EXAMPLE 55


    
    
        X=O
        R1=H
        R2=H
        R5=Me
        R6=Me
        R7=H
        R3=H
        R4=CH2O—(CH2)3-cyclohexyl
    
    


EXAMPLE 56


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=Me
        R3=CHO
        R4=CH2OCHO
    
    


EXAMPLE 57


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2OCOMe
        Salt: H2SO4+0.25H2O
        m.p. 230-232° C.
    
    


EXAMPLE 58


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=Me
        R3=COMe
        R4=CH2OCOMe
    
    


EXAMPLE 59


    
    
        X=O
        R1=COMe
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CH2Ph
        R4=CH2OCOMe
    
    


EXAMPLE 60


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2OCOCH2OH Salt: H2SO4 
        m.p. 220° C. (dec.)
    
    


EXAMPLE 61


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=COtBu
        R4=CH2OCOtBu
    
    


EXAMPLE 62


    
    
        X=O
        R1=COtBu
        R2=H
        R5=H
        R6=H
        R7=H
        R3=COOCH2Ph
        R4=CH2OCOtBu
    
    


EXAMPLE 63


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3H
        R4=CH2OCOOEt
        Salt: H2SO4 
        m.p. 214° C.
    
    


EXAMPLE 64


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2OCOCH(Me)(NH2) (L)
        Salt: 1.5H2SO4+0.25H2O
        m.p. 214° C. (dec.)
    
    


EXAMPLE 65


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2OCOCH(iPr)(NH2) (L)
        Salt: 1.5H2SO4+H2O
        m.p. 190° C. (dec.)
    
    


EXAMPLE 66


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2OCOCH(CH2Ph)(NH2) (DL)
        Salt: 2HCl+0.5H2O
        m.p. 205° C. (dec.)
    
    


EXAMPLE 67


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=Et
        R4=CH2SMe
        Salt: 2HCl+2/3H2O
        m.p. 195-196° C. (dec.)
    
    


EXAMPLE 68


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2S(O)2Me
        Salt: 2HCl
        m.p. 252-253° C.
    
    


EXAMPLE 69


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2NH2 
        Salt: 3HCl
        m.p. 264-265° C. (dec.)
    
    


EXAMPLE 70


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2NHMe
        Salt: 3HCl
        m.p. 273-274° C. (dec.)
    
    


EXAMPLE 71


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2NMe2 
        Salt: 3HCl+0.5H2O
        m.p. 224-225° C.
    
    


EXAMPLE 72


    
    
        X=NH
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2OH
    
    


EXAMPLE 73


    
    
        X=NH
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2OEt
        Salt: 3HCl
        m.p. 130° C. (dec.)
    
    


EXAMPLE 74
A compound of the formula 




EXAMPLE 75


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2SEt
    
    


EXAMPLE 76


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2S-n-propyl
    
    


EXAMPLE 77


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=CH2S-n-butyl
    
    


EXAMPLE 78


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=Me
        R3=H
        R4=H
    
    


EXAMPLE 79


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=Me
        R3=CHO
        R4=H
    
    


EXAMPLE 80


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CSNHPh
        R4=H
        m.p. >300° C.
    
    


EXAMPLE 81


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CSNHCOPh
        R4=H
        m.p. >220° C. (dec.)
    
    


EXAMPLE 82


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=COPh
        R4=H
        m.p. >300° C.
    
    


EXAMPLE 83


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=COPy
        R4=CH2CH2CH3 
        m.p. 298° C.
    
    


EXAMPLE 84


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=Rf 
        R4=H
        m.p. >300° C.
    
    


EXAMPLE 85


    
    
        X=O
        R1=COtBu
        R2=H
        R5=Ph
        R6=H
        R7=H
        R3=Rb 
        R4=Ph
        m.p. 240° C. (dec.)
    
    


EXAMPLE 86


    
    
        X=O
        R1=COiPr
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CO-(2-chlorophenyl)
        R4=H
    
    


EXAMPLE 87


    
    
        X=O
        R1=COiPr
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CO-(3-chlorophenyl)
        R4=H
    
    


EXAMPLE 88


    
    
        X=O
        R1=COiPr
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CO-(4-chlorophenyl)
        R4=H
    
    


EXAMPLE 89


    
    
        X=O
        R1=COiPr
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CO-(2-fluorophenyl)
        R4=H
    
    


EXAMPLE 90


    
    
        X=O
        R1=COiPr
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CO-(3-fluorophenyl)
        R4=H
    
    


EXAMPLE 91


    
    
        X=O
        R1=COiPr
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CO-(4-fluorophenyl)
        R4=H
    
    


EXAMPLE 92


    
    
        X=O
        R1=COiPr
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CO-(4-iodophenyl)
        R4=H
    
    


EXAMPLE 93


    
    
        X=O
        R1=COiPr
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CO-(2,3,4-trimethoxyphenyl)
        R4=H
    
    


EXAMPLE 94


    
    
        X=O
        R1=COiPr
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CO-(2-methoxyphenyl)
        R4=H
    
    


EXAMPLE 95


    
    
        X=O
        R1=COiPr
        R2=H
        R5=H
        R6=H
        R7=H
        R3=COOPh
        R4=H
    
    


EXAMPLE 96


    
    
        X=O
        R1=COiPr
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CONMe2 
        R4=H
    
    


EXAMPLE 97


    
    
        X=O
        R1=COiPr
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CO-(2-thienyl)
        R4=H
    
    


EXAMPLE 98


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CO-(2-chlorophenyl)
        R4=H
    
    


EXAMPLE 99


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CO-(3-chlorophenyl)
        R4=H
    
    


EXAMPLE 100


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CO-(4-chlorophenyl)
        R4=H
    
    


EXAMPLE 101


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CO-(2-fluorophenyl)
        R4=H
    
    


EXAMPLE 102


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CO-(3-fluorophenyl)
        R4=H
    
    


EXAMPLE 103


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CO-(4-fluorophenyl)
        R4=H
    
    


EXAMPLE 104


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CO-(4-iodophenyl)
        R4=H
    
    


EXAMPLE 105


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CO-(2,3,4-trimethoxyphenyl)
        R4=H
    
    


EXAMPLE 106


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CO-(2-methoxyphenyl)
        R4=H
    
    


EXAMPLE 107


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=COOPh
        R4=H
    
    


EXAMPLE 108


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CONMe2 
        R4=H
    
    


EXAMPLE 109


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CO-(2-thienyl)
        R4=H
    
    


EXAMPLE 110


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=CO-(4-tert-butylphenyl)
        R4=H
    
    


EXAMPLE 111


    
    
        X=O
        R1=H
        R2=H
        R5=H
        R6=H
        R7=H
        R3=H
        R4=H
        Salt: 2HCl
    
    


EXAMPLE 112


    
    
        X=O
        R1=COiPr
        R2=H
        R5=H
        R6=H
        R7=H
        R3=COMe
        R4=4-acetylaminophenyl
    
    


EXAMPLE 113


    
    
        X=O
        R1=COiPr
        R2=H
        R5=H
        R6=H
        R7=H
        R3=COMe
        R4=Ph
    
    


Measurement of inhibition of the activity of purified nitric oxide synthase (NOS)
The coproduct L-citrulline obtained during the formation of NO by purified NOS is determined quantitatively in this activity assay. The substrate of the enzyme reaction employed is 3H-radiolabelled L-arginine, which is reacted to give 3H-L-citrulline and NO. After the enzyme incubation is complete, resulting L-citrulline is removed from unused L-arginine by means of ion-exchange chromatography of the reaction mixture; the 3H activity measured by liquid scintillation then corresponds to the amount of L-citrulline, which is a direct measure of the activity of NOS.
The base medium for carrying out the enzyme reaction is TE buffer (triethanolamine, EDTA, pH 7.0). The final volume of each incubation is 100 μl. The reaction mixture is obtained by mixing the following 6 components on ice:

    
    
        1. “REA mix” (pH 7.0), which contains triethanolamine, calcium chloride, magnesium chloride, EDTA, L-arginine, calmodulin and flavine adenine dinucleotide (FAD);
        2. freshly prepared stock solution of β-nicotinamide adenine dinucleotide phosphate, reduced form (NADPH);
        3. (6R)-5,6,7,8-tetrahydro-L-biopterin dihydrochloride stock solution (BH4) or—for experiments without BH4—TE buffer instead of this;
        4. purified NO synthase from pig cerebellum or from pig liver;
        5. L-[2,3,4,5-3H]-arginine hydrochloride stock solution (1.5-2.6 TBq/mmol);
        6. substance to be tested.
    
    


The final concentrations of the components in the incubation volume of 100 μl are: Triethanolamine 50 mM, EDTA 0.5 mM, CaCl2 226 μM, MgCl2 477 μM, L-arginine 50 μM, calmodulin 0.5 μM, FAD 5 μM, NADPH 1 mM, BH4 (if added) 2 μM, substance to be tested 100 μM. After mixing the components on ice the reaction mixture is immediately incubated in a water bath at 37° C. for 15 minutes. After this incubation time, the reaction is stopped by the addition of 900 μl of ice-cold “stop buffer” (20 mM sodium acetate, 2 mM EDTA, pH 5.5) and the mixture (total volume 1.0 ml) is placed on ice. To separate off the unreacted 3H-L-arginine, the mixture is added to an ion-exchange column with 0.8 ml of Dowex AG 50 WX-8 (100-200 mesh), which was previously rinsed and equilibrated with 2 ml of stop buffer. After the application of the sample, the column is eluted twice with 1 ml of water each time. The runnings of the sample and the eluate are collected in scintillation containers and purified (total volume 3 ml). 9 ml of scintillator solution are added to the 3 ml aqueous measuring solution and the homogeneous mixture is measured for 1 minute per sample in a Tricarb 2500 TR (Packard) liquid scintillation counter. The activity found with the substance to be tested is given in percent of the activity of the control. Each substance is tested for antagonistic action at a concentration of 100 μM in the presence of 2 μM tetrahydrobiopterin and for agonistic action on the NOS in the absence of tetrahydrobiopterin. All incubations are set up in triplicate. Each experiment is repeated three times with various enzyme preparations. Some results are given in the following table.












Compounds of

Citrullin formation


example
Enzyme from
(% of the control)

















57
pig cerebellum
66.3


69
pig cerebellum
52.3


70
pig cerebellum
42.5


71
pig cerebellum
46.2


73
pig cerebellum
0.0


74
pig cerebellum
42.6


80
pig cerebellum
1.5


82
pig cerebellum
6.7


85
pig cerebellum
0.0









The following examples relate to pharmaceutical preparation forms
EXAMPLE A
Gelatin soft capsules, comprising 100 mg of active compound per capsule:













per capsule



















Active compound
100 mg



Triglyceride mixture fractionated
400 mg



from coconut fat



Capsule contents
500 mg










EXAMPLE B
Injection solution, comprising 2.0 mg of active compound per ml:
















per ml





















Active compound
2.0
mg



Polyethylene glycol 400
5.0
mg



Sodium chloride
2.7
mg



Water for injection purposes
to 1
ml










EXAMPLE C
Emulsion, comprising 60 mg of active compound per 5 ml:
















per 100





ml of emulsion





















Active compound
1.2
g



Neutral oil

q.s.



Sodium carboxymethylcellulose
0.6
g



Polyoxyethylene stearate

q.s.



Glycerol, pure
0.2 to 2.0
g



Flavoring

q.s.



Water (demineralized or distilled)
to 100
ml










EXAMPLE D
Rectal pharmaceutical form, comprising 40 mg of active compound per suppository:
















per





sup-





pository





















Active compound
40
mg



Suppository base mass
to 2
g










EXAMPLE E
Tablets, comprising 40 mg of active compound per tablet:
















per tablet





















Active compound
40
mg



Lactose
600
mg



Corn starch
300
mg



Soluble starch
20
mg



Magnesium stearate
40
mg




1000
mg










EXAMPLE F
Coated tablets, comprising 50 mg of active compound per coated tablet:
















per coated





tablet





















Active compound
50
mg



Corn starch
100
mg



Lactose
60
mg



sec. calcium phosphate
30
mg



Soluble starch
5
mg



Magnesium stearate
10
mg



Colloidal silicic acid
5
mg




260
mg










EXAMPLE G
For the preparation of the contents of hard gelatin capsules, the following recipes are suitable:

















a)
Active compound
100 mg




Corn starch
300 mg





400 mg



b)
Active compound
140 mg




Milk sugar
180 mg




Corn starch
180 mg





500 mg










EXAMPLE H
Drops can be prepared according to the following recipe (100 mg of active compound in 1 ml=20 drops):

















Active compound
10
g



Methyl benzoate
0.07
g



Ethyl benzoate
0.03
g



Ethanol, 96% strength
5
ml



Demineralized water
to 100
ml

## Claims

1. A method for the inhibition of nitric oxide production in a mammal, comprising administering to a mammal in need of such inhibition an effective amount of a pteridine compound of the formula I 



X is O or NH; 
R1 is hydrogen, methyl, (C1-C5)-alkanoyl, nicotinoyl or (1-methyl-3-pyridinio)carbonyl; 
R2 is hydrogen or methyl; 
R3 is hydrogen, methyl, ethyl, benzyl, (C1-C5)-alkanoyl, unsubstituted benzoyl, substituted benzoyl, pyridoyl, thienylcarbonyl, one of the radicals 





the radical R9R9aN—CO—, the radical R9R9aN—CS—, phenoxycarbonyl or benzyloxycarbonyl, wherein when benzoyl is substituted with a halogen, the halogen is fluorine, chlorine, or bromine;
R4 is hydrogen, (C2-C5)-alkyl, unsubstituted phenyl, substituted phenyl or the radical R4a—CH2—, wherein when phenyl is substituted with a halogen, the halogen is fluorine, chlorine, or bromine; 
R4a is hydrogen, (C1-C4)-alkylmercapto, the radical —S(O)mR10, where m is the number 1 or 2, the radical —NR11R12 or the radical —OR13, or 
R3 and R4a together are the group —CO—O—, its carbonyl carbon atom being bonded to the 5-position of the pteridine molecule; 
R5 is hydrogen or phenyl; 
R6 is hydrogen; 
R7 is hydrogen or methyl; 
R8 is (C1-C10)-alkyl or benzyl; 
R9 is hydrogen, (C1-C6)-alkyl, cyclohexyl, phenyl or benzoyl; 
R9a is hydrogen, methyl or ethyl; 
R10 is methyl; 
R11 and R12 independently of one another are hydrogen or methyl; 
R13 is hydrogen, (C1-C10)-alkyl, 2-methoxyethyl, phenyl, 3-phenylpropyl, 3-cyclohexylpropyl, (C1-C5)-alkanoyl, hydroxyacetyl, 2-amino-(C2-C6)-alkanoyl which is unsubstituted or substituted in the alkyl moiety by a phenyl radical, or ((C1-C2)-alkoxy)carbonyl; 
A8 is a pharmacologically tolerable anion; 

or a tautomeric form or pharmacologically tolerable salt thereof with the proviso that said pteridine compound is not 6-methyltetrahydropterin or 2-amino-5,6,7,8-tetrahydro-4(1)-pterinidone.

2. A method for treating at least one of pathological blood pressure decreases, inflammatory disorders, infarct damage, reperfusion damage, transplant rejection reactions, Alzheimer's disease, epilepsy, migraines, neuritis, encephalomyelitis, viral neurodegenerative diseases, hyperalgesia, kidney failure, nephritides, myocarditis, cardiomyopathy, disease of the stomach, uterus or placenta, deficiencies in sperm mobility, type 1 diabetes or insulin-dependent diabetes mellitus, atherosclerosis, and glutamate-induced neurotoxicity after cerebral ischemia, which comprises administering to a mammal in need of such treatment, an effective amount of pteridine compound of the formula I 




in which
X is O or NH; 
R1 is hydrogen, methyl, (C1-C5)-alkanoyl, nicotinoyl or (1-methyl-3-pyridinio)carbonyl; 
R2 is hydrogen or methyl; 
R3 is hydrogen, methyl, ethyl, benzyl, (C1-C5)-alkanoyl, unsubstituted benzoyl, substituted benzoyl, pyridoyl, thienylcarbonyl, one of the radicals 





the radical R9R9aN—CO—, the radical R9R9aN—CS—, phenoxycarbonyl, or benzyloxycarbonyl;
R4 is hydrogen, (C2-C5)-alkyl, unsubstituted phenyl, substituted phenyl or the radical R4a—CH2—; 
R4a is hydrogen, (C1-C4)-alkylmercapto, the radical —S(O)mR10, where m is the number 1 or 2, the radical —NR11R12 or the radical —OR13, or 
R3 and R4a together are the group —CO—O—, its carbonyl carbon atom being bonded to the 5-position of the pteridine molecule; 
R5 is hydrogen or phenyl; 
R6 is hydrogen; 
R7 is hydrogen or methyl; 
R8 is (C1-C10)-alkyl or benzyl; 
R9 is hydrogen, (C1-C6)-alkyl, cyclohexyl, phenyl or benzoyl; 
R9a is hydrogen, methyl or ethyl; 
R10 is methyl; 
R11 and R12 independently of one another are hydrogen or methyl; 
R13 is hydrogen, (C1-C10)-alkyl, 2-methoxyethyl, phenyl, 3-phenylpropyl, 3-cyclohexylpropyl, (C1-C5)-alkanoyl, hydroxyacetyl, 2-amino-(C2-C6)-alkanoyl, which is unsubstituted or substituted in the alkyl moiety by a phenyl radical, or ((C1-C2)-alkoxy)carbonyl; 
A8 is a pharmacologically tolerable anion; 

or a tautomeric form or pharmacologically tolerable salt thereof with the proviso that said pteridine compound is not 6-methyltetrahydropterin or 2-amino-5,6,7,8-tetrahydro-4(1)-pterinidone.

3. A method as claimed in claim 2, wherein X is oxygen.

4. A method as claimed in claim 2, wherein R3 is hydrogen, (C1-C5)-alkanoyl, unsubstituted benzoyl, mono-, di- or trisubstituted benzoyl, thienylcarbonyl, nicotinoyl, one of the radicals 



or R9NH—CO—, R9NH—CS— or (CH3)2N—CO—.

5. A method as claimed in claim 2, wherein R4 is hydrogen, phenyl, phenyl substituted by acetylamino group or the radical R4a—CH2—.

6. The method according to claim 5, wherein R4a is hydrogen or the radical —OR13.

7. The method according to claim 5, wherein R13 is (C1-C10)-alkyl or (C1-C5)-alkanoyl.

8. A method as claimed in claim 2 for the treatment of disorders of the nervous system selected from the group consisting of Alzheimer's disease, epilepsy and migraine.

9. The method according to claim 2, wherein in formula I,
X is O, 
R1, R2, R3, R5, R6, and R7 are hydrogen, and 
R4 is CH2OCOMe.

10. The method according to claim 2, wherein in formula I,
X is O, 
R1, R2, R3, R5, R6, and R7 are hydrogen, and 
R4 is CH2NH2.

11. The method according to claim 2, wherein in formula I,
X is O, 
R1, R2, R3, R5, R6, and R7 are hydrogen, and 
R4 is CH2NHMe.

12. The method according to claim 2, wherein in formula I,
X is O, 
R1, R2, R3, R5, R6, and R7 are hydrogen, and 
R4 is CH2NMe2.

13. The method according to claim 2, wherein in formula I,
X is NH, 
R1, R2, R3, R5, R6, and R7 are hydrogen, and 
R4 is CH2OEt.

14. The method according to claim 2, wherein in the structure of formula I is

15. The method according to claim 2, wherein in formula I,
X is O, 
R1, R2, R4, R5, R6, and R7 are hydrogen, and 
R3 is CSNHPh.

16. The method according to claim 2, wherein in formula I,
X is O, 
R1, R2, R4, R5, R6, and R7 are hydrogen, and 
R3 is COPh.

17. The method according to claim 2, wherein in formula I,
X is O, 
R1 is COtBu, 
R2, R6 and R7 are hydrogen, 
R3 is 





and
R4 and R5 are phenyl.

18. The method according to claim 2, wherein the inflammatory disorder is rheumatoid arthritis.

19. A method for treating at least one of pathological blood pressure decreases, inflammatory disorders, infarct damage, reperfusion damage, and transplant rejection reactions, which comprises administering to a mammal in need of such treatment, an effective amount of a pteridine compound of the formula I 



in which 
X is O or NH; 
R1 is hydrogen, methyl, (C1-C5)-alkanoyl, nicotinoyl or (1-methyl-3-pyridinio)carbonyl; 
R2 is hydrogen or methyl; 
R3 is hydrogen, methyl, ethyl, benzyl, (C1-C5)-alkanoyl, unsubstituted benzoyl, substituted benzoyl, pyridoyl, thienylcarbonyl, one of the radicals 




the radical R9R9aN—CO—, the radical R9R9aN—CS—, phenoxycarbonyl, or benzyloxycarbonyl; 
R4 is hydrogen, (C2-C5)-alkyl, unsubstituted phenyl, substituted phenyl or the radical R4a—CH2—; 
R4a is hydrogen, (C1-C4)-alkylmercapto, the radical —S(O)mR10, where m is the number 1 or 2, the radical —NR11R12 or the radical —OR13, or 
R3 and R4a together are the group —CO—O—, its carbonyl carbon atom being bonded to the 5-position of the pteridine molecule; 
R5 is hydrogen or phenyl; 
R6 is hydrogen; 
R7 is hydrogen or methyl; 
R8 is (C1-C10)-alkyl or benzyl; 
R9 is hydrogen, (C1-C6)-alkyl, cyclohexyl, phenyl or benzoyl; 
R9a is hydrogen, methyl or ethyl; 
R10 is methyl; 
R11 and R12 independently of one another are hydrogen or methyl; 
R13 is hydrogen, (C1-C10)-alkyl, 2-methoxyethyl, phenyl, 3-phenylpropyl, 3-cyclohexylpropyl, (C1-C5)-alkanoyl, hydroxyacetyl, 2-amino-(C2-C6)-alkanoyl, which is unsubstituted or substituted in the alkyl moiety by a phenyl radical, or ((C1-C2)-alkoxy)carbonyl; 
A8 is a pharmacologically tolerable anion; 

or a tautomeric form or pharmacologically tolerable salt thereof with the proviso that said pteridine compound is not 6-methyltetrahydropterin or 2-amino-5,6,7,8-tetrahydro-4(1)-pterinidone.

20. The method according to claim 19, wherein the pathological blood pressure decrease is due to one of septic shock or hemorrhagic shock.

21. The method according to claim 19, wherein the pathological blood pressure decrease is due to tumor therapy with cytokines.

22. The method according to claim 19, wherein the inflammatory disorder is ulcerative colitis.

23. A method of claim 19, wherein the mammal treated is susceptible to the development or the reoccurrence of pathological blood pressure decreases, inflammatory disorders, infarct damage, reperfusion damage, or transplant rejection reactions.