Synthesis, brain antihypoxic activity and cell neuroprotection of 1-substituted-3,7-dimethylxanthines.

Five newly synthesised original compounds were investigated for acute toxicity, influence on hexobarbital sleeping time, effect on the locomotor activity, and brain antihypoxic activity. Two of the compounds were tested in a model of glutamate induced neurotoxicity in the brain cell culture using a cell viability test. Our studies indicate that compounds 2a-c and 4 prolonged the survival time of mice in the model of anoxic hypoxia. Only compound 3 expressed antihypoxic activity in the model of circulatory hypoxia, evaluated with a statistical significant increase of the survival time. Compound 4 (1-[3-(2,3-dihydro-3-oxobenzisosulfonazol2-yl)-propyl]-3,7-dimethylxanthine) in concentration range 0.3-3 microM statistically significantly antagonised the glutamate induced neurotoxicity. Compound 4 is important for further investigations on in vivo models of brain dementia.

Biodegradable cross-linked prodrug of the bronchial dilator Vephylline. 2. Kinetics and quantum chemical studies on the release mechanism.

Experimental thermodynamics studies and quantum chemical reaction path calculations on the hydrolytic degradation of Poly-vephyllinemalate microspheres in acidic and basic media were performed. It was possible to make a conclusion on the release mechanism of free Vephylline as follows: a hydrolytic cleavage of the ester bonds between molecular fragments of R,S-malic acid takes place and leads to a soluble oligoester fraction. Then, further hydrolysis of the ester bonds between the xanthine fragment and R, S-malic acid leads to the release of Vephylline as free base. The hydrolytic process takes place in acidic solution with rapid degradation of the ester bonds between the malic acid monomers and by far slower degradation of the ester bonds between the malic acid and Vephylline. In basic solution both steps of the hydrolysis are fast processes leading to a complete release of free Vephylline within 1 h. The process of Vephylline release is under entropic control. The experimental results are well correlated to the results obtained after kinetics investigation and after AM1 quantum chemically calculated energy barriers in the reaction path leading to the tetrahedral intermediates of the hydrolytic reactions. This conclusion is in good accordance with an indirect study on the release mechanism of Vephylline from its polymeric prodrug, paying attention to the biological response, reported previously.

Synthesis, toxicological, pharmacological assessment, and in vitro bronchodilating activity of some 7-theophyllinylacetyloxyglycols.

The synthesis of four ester derivatives of 7-theophylline-acetic acid and glycols by DCC/DMAP-mediated esterification under mild conditions was studied. The structures of the synthesized compounds were proved by microanalyses, UV-, IR-, and 1H-NMR data. Acute toxicity assessment of the compounds in mice showed that compounds 2a-d are less toxic than aminophylline. It was shown by in vivo experiments that 2a-d had depressive action on CNS (increasing of hexobarbital sleeping time and decreasing of spontaneous locomotor activity), and they did not influence to a statistically significant extent the normal 24 hour diuresis of rats (except 2c). The results of cardiovascular screening in rats show that compounds 2a and 2c decreased the heart rate of rats. A pharmacological study of the in vitro broncholytic effect (IC50 and pD2 values) of the derivatives and aminophylline showed that 2c exhibited good broncholytic effect in vitro especially in acetylcholine and serotonin induced guinea pig tracheal contraction. It was demonstrated that compounds 2b,c exerted a stronger inhibitory effect on the enzymic activity of phosphodiesterase in concentration 2 x 10(-3) M than aminophylline.

Synthesis, toxicological, pharmacological, and bronchodilating activity in vitro of some xanthineacetic acid derivatives.

The possibility of the preparation of some ester derivatives of dimethylxanthines from 1-theobromine- and 7-theophylline acetic acids and 7-(2-hydroxyethyl)-theophylline by DCC/DMAP-mediated esterification under mild conditions was studied. The structures of the compounds synthesized and by products isolated were demonstrated by microanalyses, UV-, IR-, and 1H NMR data. Acute toxicity assessment of the compounds on mice showed that compounds 4, 5, 6, and 7 are less toxic than aminophylline. A pharmacological study of the in vitro broncholytic effect (IC50 and pD2 values) of the derivatives and aminophylline showed that the new compound 4 (1,2,3,6-tetrahydro-1,3-dimethyl-2,6-dioxo-7H-purine-7-acetic acid 2-(1,2,3,6-tetrahydro-1,3-dimethyl-2,6-dioxo-7H-purin-7-yl)ethyl ester) has a strong bronchodilating effect on serotonine- and acetylcholine-induced spasm in guinea pig trachea. The same compound does not influence barbiturate-induced hypnosis and locomotor activity, unlike to the effect of the aminophylline, used as a reference substance.