Influence of newly-synthetized xanthine derivatives on phosphodiesterase with high Km in homogenates of different organs and on lipolysis in vivo.

Six newly-synthetized 7-N-basically substituted xanthine derivatives were studied for inhibitory action on phosphodiesterase with high Km in homogenates from brain, lung and epididymal fatty tissue. Theophylline is used for comparative purposes. The effect of part of the compounds on lipolysis in vivo is also studied. Some of the newly-synthetized compounds are found to manifest a marked ability to inhibit the enzyme studied in brain and lung homogenates, and compound with code V has equal action to that of theophylline. The newly-synthetized compounds are poor inhibitors of the enzyme in epididymal fatty tissue, unlike theophylline which demonstrates the same inhibitory capacity as in the other homogenates. These data correlate with the results obtained when studying lipolysis. Theophylline in a dose of 50 mg/kg i. p. increases twice the serum content of the free fatty acids, while the newly-synthetized compounds have no effect on it, even when applied in high doses.