Abstract: The invention relates to cyclic bioisosteres of derivatives of a purine system having a general structural formula where R?Li, Na, K, R1?—H, —NH2, —Br, —Cl, —OH, —COOH, B?—N?, —CH?, Z=-CH?, —N?, A=-N? at B?—N?, Z=-CH—, A=-CH? at B?—N?, Z=-CH—, A=-CH? at B?—N?, Z=-N?, A=-CH? at B?—CH?, Z=-CH?, A=-CH? at B?—CH?, Z=-N?, and their pharmacologically acceptable salts having a normalizing effect on endocellular processes, in particular, it is capable eliminating endocellular metabolic acidosis and capable of binding excessively formed free radicals, in particular, free-radical forms of oxygen, capable of normalizing the nitrergic mechanisms of the cells, and also capable of interreacting with adenosine-sensitive receptors on the membrane of non-nuclear cells and in nuclei-containing cells to decrease the aggregation of thrombocytes. The compounds according to the invention have hepatoprotective effect and can be used for producing pharmaceutical compositions on their base.