Synthesis and activity against HBV of novel Tetra-seconucleoside analogues of dyphlline having the acyclic chains of ACV and HBG.

Selective alkylation of dyphylline (1) with (2-acetoxyethoxy)methyl bromide (2a) or 4-acetoxybutyl bromide (2b) afforded 3'-O-[(acetoxyethoxy)methyl]dyphylline (3a) and 3'-O-(4-acetoxybutyl)-dyphylline (3b), respectively. A trans esterification process rather than alkylation of the dihydroxy-propyl side chain in 1 had taken place during the reaction with 2-p-toluoyloxy)ethyl chloride (5) to afford the respective 3'-toluoyloxy derivative 7 and not the anticipated 3'-O-[(p-toluoyloxy)ethyl]-dyphylline (6). Deacylation of 3a,b and 7 afforded 4a,b and 1, respectively. Viral screening of selected compounds against HBV has been investigated.

Convulsant effects of some xanthine derivatives in genetically epilepsy-prone rats.

The behavioural and electrocorticographic (ECoG) convulsant effects of several xanthine derivatives injected intraperitoneally (i.p.) were studied in genetically-epilepsy prone rats. The aim of the study was to evaluate the relationship among convulsant potency, molecular structure and lipophilicity of some xanthines. Animals were injected i.p. with various doses (250-1000 micromol/kg) and a different convulsant potency was observed among the various xanthines tested. IBMX (3-isobutyl-1-methylxanthine), theophylline (1,3-dimethylxanthine) and caffeine (1,3,7-trimethylxanthine) induced an epileptogenic pattern that consisted in an initial phase characterized by wet-dog shakes followed by head tremor, nodding, clonic convulsion and they appeared to be the most potent xanthines among those studied. During seizures, the electrocortical activity was usually characterized by single or multiple sharp- or spike-wave episodes followed by polyspike discharges. After the highest doses of IBMX, theophylline and caffeine, the animals react with falling down, transient tonic clonic seizures, escape response and generalized seizures followed by post-ictal period. Equimolar doses of 8-chlorotheophylline and theobromine (3,7-dimethylxanthine) produced less evident epileptic responses in comparison to previous compounds, whereas no epileptic signs were observed following the administration of enprofylline (3-propylxanthine), etofylline [7-(2-hydroxyethyl)theophylline], diprophylline [7-(2,3-dihydroxy-propyl)theophylline] and doxofylline [7-(1,3-dioxolan-2-ylmethyl) theophylline]. Lipophylicity of the compounds was determined, but no convincing correlations were found between the rank order of lipophilicities and the convulsant potencies of the compounds studied. On the other hand, structure-activity relationship was also investigated. We suggest that the substitution pattern on the xanthine nucleus may explain, in part, the different convulsant potency of the compounds studied. Furthermore, a selective antagonism of adenosine subtype receptors should be considered.

The inhibitory effect of theophylline on cell cycle kinetics of human lymphocytes in vitro.

The effect of theophylline (TF) on proliferation of lymphocytes in phytohaemagglutinin (PHA), concanavalin A (Con A) and pokeweed mitogen (PWM) freshly stimulated 3-4 days cultures or of 14-days cultured lymphoblasts was studied. Proliferation was estimated by measurement of incorporation of tritiated thymidine (3H-TdR), and by microscopic analysis of cellular divisions progression up to the 4th generation of cells cultured in presence of 5-bromodeoxyuridine (BrdUrd). The strongest inhibition of proliferation was observed when TF was added at the beginning of the cultures. However, when TF was added for the last 20 h of the cultures, a significant decrease in number of the third (M3) and fourth (M4) generation cells was noted and M3/M4 ratio increased from 6.4 up to 19.1. TF inhibited also incorporation of 3H-TdR into cultured lymphoblasts. The obtained data indicate an inhibitory effect of TF both an activation and cell cycle progression of lymphocytes.

Probenecid inhibition of the renal excretion of dyphylline in chicken, rat and man.

The effect of probenecid on the renal excretion of dyphylline was studied in chicken, rat and man. Dyphylline was found to be actively excreted when measured by the Sperber preparation in hens, the isolated perfused kidney of the rat and clearance studies in man. In each study probenecid significantly decreased dyphylline excretion demonstrating that dyphylline occupied the renal organic anion transport system. This same drug interaction, at the level of the renal excretory system, in these three species occurred at comparable concentrations of dyphylline and probenecid.

Theophylline and dyphylline pharmacokinetics in the horse.

The pharmacokinetics of theophylline and dyphylline were determined after IV administration in horses. In a preliminary experiment, the usual human dosage (milligram per kilogram) of each drug was given to 1 horse. Results were used to calculate dosages for a cross-over study, using 6 horses for each drug. Theophylline plasma concentrations decreased triexponentially in 5 of 6 healthy horses after IV infusion of 10 mg of aminophylline/kg of body weight for 16 to 32 minutes. In the 6 horses, total body elimination rate constants were variable, and the half-life of theophylline was 9.7 to 19.3 hours. Clearance was 42.3 to 69.2 ml/hr/kg. The initial distribution phase was rapid (t1/2 approx 3.5 to 4 minutes); a 2nd distribution phase was slower (t1/2 approx 1.5 to 2 hours). Plasma concentrations of theophylline were in the assumed effective range (10 to 20 micrograms/ml) from 15 minutes until 40 minutes after time zero. The mean apparent volume of distribution was 1.02 L/kg. After bolus IV injection of dyphylline (20 mg/kg), pharmacokinetics were best described by a 2-compartment open model in 2 horses and by a 3-compartment open model in 4 horses. In the 6 horses, elimination half-life of dyphylline was 1.9 to 2.9 hours, and clearance was 200 to 320 ml/hr/kg. Plasma concentrations (approx 50 micrograms/ml) were observed at 10 minutes after injection without adverse effects. Concentrations greater than 10 micrograms/ml were observed from time zero to about 1.5 hours after injection. Theophylline induced significant increases in heart rate, but dyphylline did not affect heart rate significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

[Effects of diprophylline on pulmonary hypertension in patients with chronic pulmonary disease].

The present study was undertaken to evaluate the short-term effects of diprophylline on hemodynamic and gases exchange in 10 patients in stable condition with chronic pulmonary disease. Diprophylline decreased the pulmonary vascular resistance by markedly reducing the mean pulmonary arterial pressure but didn't change cardiac output significantly. Diprophylline also caused a significant decrease in arterial carbon dioxide tension, but there was no significant difference between the level of PaO2, SaO2 and A-aDo2 before and after the administration of diprophylline.

[Hypolipidemic effect of the new diprophylline derivative, [2-hydroxy-3-(theophylline-7-ol] propyl ester of 4-benzylhydroxybenzoic acid]. / Gipolipidemicheskoe deistvie novogo proizvodnogo diprofillina [2-gidroksi-3-(teofillin-7-il)] propilovogo éfira 4-benziloksibenzoinoi kisloty.

A new derivative of diprophylline--[2-hydroxy-3(theophylline-7-ol)] propyl ester 4-benzyloxybenzoic acid was shown to decrease the content of cholesterol and of atherogenic lipoproteins in blood serum of hyperlipidemic guinea pigs. In blood serum of rabbits the new substance studied decreased cholesterol, free fatty acids and malonic dialdehyde concentrations.

Screening-based discovery of drug-like O-GlcNAcase inhibitor scaffolds.

O-GlcNAcylation is an essential posttranslational modification in metazoa. Modulation of O-GlcNAc levels with small molecule inhibitors of O-GlcNAc hydrolase (OGA) is a useful strategy to probe the role of this modification in a range of cellular processes. Here we report the discovery of novel, low molecular weight and drug-like O-GlcNAcase inhibitor scaffolds by high-throughput screening. Kinetic and X-ray crystallographic analyses of the binding modes with human/bacterial O-GlcNAcases identify some of these as competitive inhibitors. Comparative kinetic experiments with the mechanistically related human lysosomal hexosaminidases reveal that three of the inhibitor scaffolds show selectivity towards human OGA. These scaffolds provide attractive starting points for the development of non-carbohydrate, drug-like OGA inhibitors.

Efficacy of theophylline and its N-7-substituted derivatives in experimentally induced bronchial asthma in the guinea-pig.

A study has been made of the bronchospasmolytic actions of theophylline and some ot its N-7-substituted derivatives administered by i.v infusion in anaesthetized guinea pigs, in which experimental bronchial asthma was induced by i.v. administration of histamine, 5-hydroxytryptamine and bradykinin. Bronchoconstriction was measured as changes in tidal volume, airflow rate, intrapleural pressure fluctuations and respiratory frequency. Dynamic lung compliance and pulmonary resistance was computed and recorded simultaneously. In addition blood pressure and heart rate were recorded. Theophylline, proxyphylline, diprophylline and etophylline when given alone had hardly an effect on lung function; relatively high doses of the drugs caused a fall in blood pressure and an increase in heart rate. Acephylline infusion in relatively high doses produced a decrease of dynamic lung compliance and an increase of pulmonary resistance. Some animals died. Theophylline, proxyphylline, diprophylline and etophylline were effective in reducing the mediator-induced bronchoconstriction. Protective effects correlated considerably (R = 0.75-0.82) with the plasma concentrations. The magnitude of these protective effects increased with the plasma concentration. Effective doses of proxyphylline, diprophylline and etophylline were much higher than those of theophylline. Acephylline was completely inactive in reversing the mediator-induced bronchoconstriction. At relatively high doses it increased the bronchoconstrictive effects of the mediators. It is concluded that diprophylline, proxyphylline and etophylline, like theophylline, are highly effective bronchospasmolytics, but does of the individual drugs must be adjusted according to the derivative used. Theophylline is by far the most effective of the four compounds. On the basis of this study and recent pharmacokinetic data in man the therapeutic value of acephylline in asthmatics seems doubtful.

The effect of amino acid derivative of clofibric acid (WKLB-5), and theophylline monoester of nicotinic acid (ME1) on the development of experimental atherosclerosis in rabbits.

In order to determine the efficacy of new compounds--an amino acid derivative of clofibric acid (WKLB-5), and a theophylline monoester of nicotinic acid (ME1)--a high fat diet (HFD) was applied to rabbits for 3 months, with or without the above mentioned compounds. The HFO included coconut oil, cholesterol and cholic acid. A substantial hypolipemic activity of those compounds was demonstrated; however, the studied lipid fractions did not undergo normalization, except FFA whose level after ME1 administration was distinctly lower than in control animals. Sudanophilic changes were found on 83% of surface of the interior membrane of aorta in rabbits kept on the HFD only, on 35% of surface--in rabbits treated with the HFD + WKLB-5, and on 75% of surface--in rabbits treated with the HFD + ME1. Thus in those animals no parallelism between the hypolipemic and antiatherosclerotic activities was observed.

Xanthines inhibit 3T3 fibroblast proliferation.

It is believed that xanthines can inhibit cell proliferation by elevating intracellular cAMP. Therefore, these compounds can be useful in hyperproliferative disorders. Our aim was to assess the efficacy of theophylline, caffeine and dyphylline on 3T3 fibroblast proliferation. 3T3 subconfluent cultures were incubated for 3 days with the xanthine derivatives (1 mM-1 microM). At 1 and 0.1 mM the three derivatives exhibited marked inhibition of fibroblast proliferation. Theophylline and caffeine were more potent than dyphylline. At a concentration of 1 mM, the three xanthine derivatives also inhibited proliferation of psoriatic dermal fibroblast, albeit to a lower extent. Caffeine was the most active compound followed by theophylline and dyphylline. We conclude that xanthine derivatives are good candidates for use as fibroblast antiproliferative drugs. We also conclude that 3T3 fibroblasts appear to be a valid system for the pharmacological screening of fibroblast antiproliferative drugs.

Hypolipemic and potential antiatherosclerotic properties of diprophyllinyl-4-benzyloxybenzoate.

To assess the hypolipemic and antiatherosclerotic activity of diprophyllinyl-4-benzyloxybenzoate guinea-pigs were kept on a high-lipid diet alone or with the tested compound for 21 days, and rabbits--for 3 months. It was found that diprophyllinyl-4-benzyloxybenzoate displays a distinct hypolipemic activity, particularly with respect to cholesterol, both in guinea-pigs and rabbits. It also depresses the cholesterol and the trigliceride content in liver homogenates and shows a tendency to normalize the low-density-lipoprotein fraction in guinea-pigs, as well as cholesterol of the high-density lipoprotein fraction, and malon dialdehyde in rabbits. The area of intima covered with atheromatous plaques was smaller in rabbits receiving the high-lipid diet with diprophyllinyl-4-benzyloxybenzoate than in those receiving that diet alone.

Influence of different methylxanthines on the anticonvulsant action of common antiepileptic drugs in mice.

The protective activity of carbamazepine (CBZ, 60 min before testing), phenobarbital (PB, 120 min), phenytoin (PHT, 120 min), and valproate (VPA, 30 min) alone or concurrent with methylxanthine derivatives was evaluated against maximal electroshock-induced seizures (MES) in male mice. All drugs were administered intraperitoneally (i.p.), and the protection offered by antiepileptic drugs (AEDs) was expressed as ED50 in mg/kg. Caffeine sodium benzoate in doses of 0.0595-0.476 mmol/kg (11.55-92.4 mg/kg) distinctly reduced the anticonvulsant efficacy of PB, in the highest dose tested with an increase in ED50 value from 19.5 to 38 mg/kg. This methylxanthine derivative in the dose range of 0.119-0.476 mmol/kg (23.1-92.4 mg/kg) also efficiently inhibited the protective action of PHT. When combined with caffeine (0.238 and 0.476 mmol/kg), the ED50 of PHT was raised from 12 to 17 and 24 mg/kg, respectively. In doses of 0.238 and 0.476 mmol/kg, caffeine also diminished the efficacy of CBZ and VPA, and at the highest dose tested the methylxanthine elevated the respective ED50s from 13 to 20.5 mg/kg and from 270 to 420 mg/kg. Generally caffeine sodium benzoate (up to 0.476 mmol/kg) did not affect the plasma levels of studied AEDs, and only at 0.476 mmol/kg did it significantly decrease the level of PHT. Among the other methylxanthines, pentoxifylline (0.238-0.476 mmol/kg; 66.3-132.5 mg/kg) and diprophylline (0.952 mmol/kg; 242.1 mg/kg) inhibited the protective potential of PHT and the respective ED50s were raised from 12 to 16.5, 15.5, and 14 mg/kg. No significant alterations in PHT plasma levels were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Overadditive synergism between theophylline, diprophylline and proxyphylline in tracheal smooth muscle relaxation.

The effects of theophylline, proxyphylline and diprophylline on cAMP-phosphodiesterase (PDE), tracheal smooth muscle tone and cAMP-levels were studied in guinea-pig tracheal preparations, and on contractile force in guinea-pig atria. Theophylline and proxyphylline inhibited tracheal PDE-activity to similar extents (I50 approximately 40 micrograms/ml) whereas diprophylline was about 5 times less effective. Half-maximum relaxation of tracheal smooth muscle was obtained with 25 micrograms/ml theophylline, 100 micrograms/ml proxyphylline and 250 micrograms/ml diprophylline. Marked rises in cAMP-levels were obtained with theophylline and, to a lesser extent with proxyphylline whereas diprophylline was almost ineffective. In combination, the relaxant effect of theophylline was over-additively enhanced by diprophylline plus proxyphylline (combination product of these three methylxanthines: Neobiphyllin) but its cAMP-increasing effect (at lower doses) was not, indicating that the potentiated relaxing action was not due to higher levels of cAMP. Diprophylline in contrast to theophylline or proxyphylline had almost no positive inotropic effect in guinea-pig atria which supports the assumption that the mechanism of tracheal smooth muscle relaxation of diprophylline is different from that of theophylline and proxyphylline and unrelated to cAMP. These findings agree with and explain the favourable anti-asthmatic effects obtained with a combination of theophylline, proxphylline and diprophylline.