Theophyllinemethyldithiolan and theophyllinemethyldithianyl derivates, a method for their preparation and pharmaceutical compositions in which they are included

Abstract: New derivatives of theophylline are described, which have the general formula: in which R is selected from the group consisting of 2′-­ (1′-oxy-1′, 3′-dithiolanyl), 2′-(1′, 3′-dithiolanyl) and 2′-(1′,3′-dithianyl), possibly substituted in position 4′. The derivatives have high antibronchospastic, antitussive and mucolytic activities.

Description: The present invention relates to new derivatives of theophylline substituted in position 7, which have antibroncospastic and antitussive activities and are usable in the treatment of disorders of the respiratory system. U.S. Patent US-A-4,187,308 in the name of the Applicant describes the antibronchospastic and antitussive activity of the compound 7-[2'-(1'-3'-dioxolanyl)-methyl]-theophylline and its use in the therapeutic treatment of bronchospasms, bronchial asthma and chronic bronchitis. FR-A-2 480 286, also in the name of the Applicant, describes a class of variously substituted theophyllinemethyldioxolan derivatives characterised by antitussive and antibronchospastic activity. EP-A-0 171 005 describes xanthinylmethylthiazolidines which are useful as mucus regulating, bronchodilators and antitussive agents. In continuing his research into the production of new theophylline derivatives with greater antibronchospastic and antitussive activity than known compounds, the Applicant has succeeded in identifying a new class of compounds. Thus a subject of the present invention is constituted by new theophyllinemethyldithiolan and theophyllinemethyldithianyl derivatives having the general formula: in which R is selected from the group consisting of , and their pharmaceutically acceptable salts. Surprisingly, the compounds covered by the general formula defined above have mucolytic activity as well as antibronchospastic and antitussive activity. The compounds indicated above, are more particularly, the following: Compound 1: 7-[2'-(1',3'-dithiolanyl)-methyl]-theophylline, melting point 125-127°C. Compound 2: 7-[2'-(1',3'-dithianyl)-methyl]-theophylline, melting point 151-153°C. Compound 3: 7-[2'-(1',3'-dithiolanyl)-methyl]-theophylline sulphoxide, melting point: 200-202°C and Compound 4: 7-[2'-(1',3'-dithiolanyl)-methyl]-theophylline sulphoxide, the diastereoisomer of compound 3, melting point 201-203°C. In particular, the aforementioned compounds (1) - (4) do not cause side effects or habituation at therapeutic doses, even with prolonged treatment and have negligible toxicity. All these compounds have shown bronchomyorelaxing activity and simultaneous mucolytic action; Compound (1) is the one which has the most favourable therapeutic index. A further subject of the present invention is constituted by the methods for the preparation of the aforementioned compounds. In particular, the method for the preparation of the derivatives of formula (I), in which R is constituted by the radicals (II) and (III) given above, includes the step of reacting 7-theophylline-acetaldehyde with a dithiol selected from the group consisting of ethanedithiol and 1, 3-propanedithiol. The synthesis is preferably carried out in ethereal solution at a temperature no higher than 75°C in the presence of acid catalysts of the Lewis acid type, anhydrous halogen hydracids, or sulphuric acid. The solvent is removed and the product of the synthesis is then purified preferably in a chloroform solution, by basic washing and subsequent chromotography on silica gel. The general method for the synthesis of the compounds (3) and (4) comprises the reaction of the dithiolan derivative with hydrogen peroxide. The dithiolan derivative is preferably dissolved in glacial acetic acid and the reaction is carried out with hydrogen peroxide preferably 35% hydrogen peroxide at room temperature. Upon completion of the reaction, the product is precipitated with ethyl ether and the compound obtained is collected in a Buckner funnel. The diastereoisomeric derivatives (3) and (4) are separated and purified in a column of silica. In the preparative tests carried out, the IR, NMR and mass spectra confirmed the structures shown above. Example 1 Preparation of compound (1): 7-[2′-(1′,3′-dithiolanyl)-methyl]-theophylline. 10g of 7-theophylline-acetaldehyde (molecular weight 222) are dissolved in 350ml of anhydrous dioxan and heated to a temperature of between 60 and 70°C. 10ml of ethane-1,2-dithiol and 12.5ml of boron trifluoride etherate are added. The mixture is left to react for 5 hours, while the above temperature is maintained. The dioxan is removed under vacuum and the residue is taken up with 300ml of chloroform. The chloroform solution is washed with a 5% NaOH solution and then with a saturated NaCl solution. The solvent is removed and the product is purified in a column of silica with a CH₂Cl₂/ethanol (99:1) eluent. Yield: 70%. Recrystallised from methanol, the compound has a melting point of 125-127°C. The mass, IR and NMR spectra confirm the structure of compound (1). The compounds according to the invention and their pharmaceutically-acceptable salts may be administered in conventional pharmaceutical forms, such as tablets, capsules, suspensions, granules, and suppositories, together with conventional excipients, carriers, colouring agents and sweeteners, particularly for the treatment of bronchospasms, bronchial asthma, and chronic obstructive bronchitis associated with mucous and spastic coughing. By way of example, the compositions of preferred pharmaceutical forms are shown below. Pharmaceutical forms Tablets and capsules having the following composition: Dithiolan 0.200 g mannitol 0.070 g microcrystalline cellulose 0.052 g colloidal silica 0.026 g talc 0.024 g P.V.P. 0.020 g magnesium stearate 0.008 g 400mg tablets and capsules Dithiolan 0.400 g mannitol 0.100 g microcrystalline cellulose 0.052 g colloidal silica 0.026 g talc 0.050 g P.V.P. 0.030 g magnesium stearate 0.010 g 500 mg retarded tablets with the following composition: Dithiolan 500 mg sucrose 240 mg maize starch 50 mg magnesium stearate 10 mg microcrystalline cellulose 100 mg diffulac 100 mg 2.5% oral suspension The suspension contains per 100 g: Dithiolan 2.50 g sorbitol, 70% 50.00 g levilite 4.00 g emulsional 1.20 g soluble extract of orange 1.00 g methyl p-hydroxybenzoate 0.13 g distilled water qs. up to 100 g effervescent granules each packet contains: neonatalogical use paediatric use Dithiolan 0.050 g 0.100 g lyophylised citrus fruit 0.5 g 1 g fructose 1.25 g 2.5 g citric acid 0.25 g 0.5 g sodium bicarbonate 0.35 g 0.7 g suppositories for paediatric use Dithiolan 200 mg semisynthetic glycerides qs. up to 1.5 g suppositories for adult use Dithiolan 400 mg semisynthetic glycerides qs. up to 2.5 g Pharmacological activity The pharmacological activity of the preferred compounds according to the invention was tested in comparison with the activity of known compounds such as doxophylline (7-[2'-(1',3'-dioxolanyl)-methyl]-theophylline) and aminophylline by means of a series of tests in vitro and in vivo . Tests in vitro a) Activity of compounds (1), (2), (3), (4) according to the invention, doxophylline and aminophylline on completely-removed guinea-pig tracheas. Thirty white guinea-pigs were used, from which the tracheas were removed, after they had been killed by ethereal anaesthesia. The tracheas were placed in a 50ml bath of Krebs solution, suitably oxygenated and thermoregulated at a temperature of 37°C. The lower end of the trachea was closed while the upper end was connected to a polythene tube connected to a transducer for measuring volume differences connected to a polygraph, according to D. Jamieson's method 1962, Brit. J. Pharmacol. and Chemiotherapy, 19 , 286, partially modified. Both the trachea and the polythene tube were filled with Krebs solution. The responses of the tracheas thus prepared to acetylcholine and histamine were investigated before and after the addition of the product to the bath. The results obtained are shown in Table I and in figure 1. EFFECTS OF COMPOUNDS 1, 2, 3, 4, DOXOPHYLLINE AND AMINOPHYLLINE ON THE CONSTRICTIVE ACTION OF HISTAMINE DI-HYDROCHLORIDE (5 microg/ml) ON COMPLETELY-REMOVED GUINEA-PIG TRACHEAS (see figure 1). *---* COMPOUND 1 ED 50 = 126.119 C.L. 95% = 52.3643 - 303.757 C.L. 99% = 25.1208 - 633.179 X---X COMPOUND 2 ED 50 = 837.153 C.L. 95% = 268.149 - 2613.56 C.L. 99% = 103.565 - 6767 0---0 COMPOUND 3 ED 50 = 530 C.L. 95% = 164.287 - 1524.25 C.L. 99% = 76.2289 - 3684.96 $---$ DOXOPHYLLINE ED 50 = 177.161 C.L. 95% = 165.656 - 189.465 C.L. 99% = 156.616 - 200.401 £---£ AMINOPHYLLINE ED 50 = 206.105 C.L. 95% = 116.876 - 363.458 C.L. 99% = 72.7532 - 583.883 . --- . COMPOUND 4 ED 50 = 2241.84 C.L. 95% = 424.242 - 11846.7 C.L. 99% = 105.549 - 47616.2 C.L. = Confidence Level The tests in vivo were only conducted on compound (1), which, on the basis of the results obtained in vitro , was the most active. a) Comparative activity of compound (1) (7-[2′-1′,3′ dithiolanyl)-methyl]-theophylline), doxophylline and aminophylline on bronchospasm by acetylcholine chloride (0.075 mg/kg i.v.), in guinea-pigs . For these tests, Konzett and Roesler's method (1940) Arch. Exp. Path. Pharmak, 191 , 71, was used with some of the modifications of Collier H.O.J. (1960), Brit. J. Pharmcol. 15 , 290. Male guinea-pigs weighing 300-450g were used under urethane anaesthesia (1g/kg i.p.). The animals were suitably prepared by insertion of a cannula in the jugular vein for intravenous administrations while the trachea was connected to an artificial respiration pump (Palmer) adapted for small animals, which was operated at a frequency of approximately 70 insufflations per minute. The pneumogram was recorded by means of a transducer on a polygraph (Battaglia-Rangoni). Bronchospasm was induced in the guinea-pig by means of intravenous injection of acetylcholine at a dose of 0.075 mg/kg i.v. After two equal responses to the acetylcholine, the drugs under study were administered i.v. The results obtained are shown in Table II and Figure 2. EFFECT OF COMPOUND 1, DOXOPHYLLINE AND AMINOPHYLLINE ON BRONCHOSPASM, BY ACETYLCHOLINE CHLORIDE (0.075mg/kg i.v.) IN GUINEA-PIGS (figure 2). *---* COMPOUND 1 ED 50 = .996124 C.L. 95% = .104729 - 9.47454 C.L. 99% = 1.59445E-02 - 62.2324 X---X DOXOPHYLLINE ED50 = 2.01949 C.L. 95% = 1.18433 - 3.44359 C.L. 99% = .758225 - 5.37881 0---0 AMINOPHYLLINE ED50 = 4.97479 C.L. 95% = .300261 - 82.4231 C.L. 99% = 2.87493E-02 - 860.839 C.L. = Confidence Level The results given in the Table show that the antibronchospastic effect of compound (1), 7-[2′-(1′,3′-dithiolanyl)-methyl]-theophylline is approximately twice that of doxophylline and approximately five times that of aminophylline. b) Mucolytic activity of compound 1, doxophylline and bromohexyne hydrochloride For these tests the method described by Perry, W.F., Boyd, E.M., J. Pharmacol., 1941, 73 , 65 and suitably modified by us was used. New Zealand-type, male, white rabbits weighing 2.8 -3.5 kg. were used. Pre-operative preparation consisted of treatment with 9mg/kg i.m. of a non-stupefying central analgesic (tilidine) and local anaesthesia in the tracheal region with xylocaine (0.9 mg/kg - 1% solution). The surgical operation commenced 15-20 minutes after the pharmacological pre-treatment. The trachea was exposed and a hole approximately 5-6mm in diameter was made in its ventral side. The trachea was then introduced into the lower arm of a three-way polypropylene cannula, which had been cut suitably, longitudinally so as to connect the hole made in the trachea with the aperture of the third arm (vertical) of the cannula, and thus put it into communication with the outside. Thus, the cannula surrounded the outside of the trachea and was fixed " in loco " with sterile surgical silk thread. A polypropylene container was attached to the vertical arm of the cannula for collecting the mucous (capacity approximately 2ml), and the wound was then sutured. The tracheal mucous was collected for four hours before the oral administration of the substance under test and for four hours after the treatment. The results obtained are shown in Table III below. From these, it is clear that the compound (1) has a dose-related mucolytic activity: at a dose of 100 mg/kg it was more active than bromohexyne hydrochloride at a dose of 400 mg/kg; doxophylline, however, showed no mucolytic activity. Determination of acute toxicity Determination of the acute oral toxicity of compound (1) was carried out both in mice and in rats, with the use of doxophylline and aminophylline as reference products. The products were administered in a 0.5% aqueous suspension of carboxymethylcellulose at a concentration of 1 ml/100g of body weight. After treatment with the respective drugs, the animals were observed for 20 consecutive days, their general condition, behaviour and mortality being noted. The LD₅₀ values were calculated by Litchfield and Wilcoxon's statistical method (1949) J. Pharmacol. Exp. Therap. 96 , 99.

Claims: Claims for the following Contracting States : AT, BE, CH, DE, FR, GB, IT, LI, NL, SE Theophyllinemethyldithiolan and theophyllinemethyldithianyl derivatives having the general formula: in which R is selected from the group consisting of: and their pharmaceutically acceptable salts. A compound according to claim 1 which is 7-[2'-(1',3'-dithiolanyl)-methyl]-theophylline. A compound according to claim 1 which is 7-[2'-(1',3'-dithianyl)-methyl]-theophylline. A compound according to claim 1 which is 7-[2'-(1',3'-dithiolanyl)-methyl]-theophylline. sulphoxide, and its diastereoisomer. Formula (I) derivatives according to claim 1 for use in the therapeutic treatment of disorders of the respiratory system. The use of derivatives of the general formula (I) according to claim 1 for the preparation of a medicament having antibronchospastic, antitussive and mucolytic activity. Pharmaceutical compositions having antibronchospastic, antitussive and mucolytic activity including at least one of the compounds according to Claims 1 to 4 as the active ingredient. A method for the preparation of theophylline derivatives according to claim 1 having the general formula (I) in which R is selected from the group consisting of: characterised in that it comprises the step of reacting 7-theophylline-acetaldehyde with a thiol selected from the group consisting of: in the presence of acid catalysts selected from the group consisting of Lewis acids, anhydrous halogen hydracids and sulphuric acid. A method according to Claim 8, characterised in that the reaction is carried out in an ethereal solution at a temperature no higher than 75°C. A method for the preparation of theophylline derivatives according to claim 1 having the general formula (I), in which R is characterised in that it includes the step of reacting the dithiolan derivative with hydrogen peroxide. Claims for the following Contracting States : ES, GR The use of theophyllinemethyldithiolan and theophyllinemethyl- dithianyl derivatives having the general formula: in which R is selected from the group consisting of: and their pharmaceutically acceptable salts for the preparation of a medicament for the treatment of spastic disorders of the respiratory system. Use according to Claim 1 wherein the derivative is 7-[2'-(1',3'-dithiolanyl)-methyl]-theophylline. Use according to Claim 1, wherein the derivative is 7-[2'-(1',3'-dithianyl)-methyl]-theophylline. Use according to Claim 1, wherein the derivative is 7-[2'-(1',3'-dithiolanyl)-methyl]-theophylline sulphoxide, and its diastereoisomer. The use of derivatives of the general formula (I) according to claim 1 for the preparation of a medicament having antibronchospastic, antitussive and/or mucolytic activity. A method for the preparation of theophylline derivatives having the general formula (I) according to claim 1 in which R is selected from the group consisting of: characterised in that it comprises the step of reacting 7-theophylline-acetaldehyde with a thiol selected from the group consisting of: in the presence of acid catalysts selected from the group consisting of Lewis acids, anhydrous halogen hydracids and sulphuric acid. A method according to Claim 6, characterised in that the reaction is carried out in an ethereal solution at a temperature no higher than 75°C. A method for the preparation of theophylline derivatives according to claim 1 having the general formula (I), in which R is characterised in that it includes the step of reacting the dithiolan derivative with hydrogen peroxide.

Inventors: DE VERCELLI SERGIO, FRANZONE JOSE SEBASTIAN, DE VERCELLI,SERGIO, FRANZONE, JOSE SEBASTIAN, Franzone, José Sebastian
Applicants: ABC IST BIOLOG CHEM SPA, ISTITUTO BIOLOGICO CHEMIOTERAPICO  "ABC" S.P.A.
Application year: 1987
Main classification: C07D473
IPC codes: C07D473, A61P11, A61K31