In this work, four derivatives of arginine with biologically active acids: acetylsalicylic, butyric, nicotinic, and succinic acids were obtained and characterized using UV-visible, IR, 1H NMR, and 13C NMR spectroscopy. In addition to spectroscopic analyses, DFT calculations were applied to predict the physicochemical properties of the studied compounds. The IR and NMR parameters were evaluated and compared with those experimental results obtained in the spectra. Moreover, the electronic transitions in the UV-Vis region of the electromagnetic spectrum were studied through the visualization of FMOs as well a calculation of energy gap values and TD-DFT calculations. It was found that the compounds maximally absorb the electromagnetic radiation at a wavelength range of 156.78–181.54 nm which can be due to π–π* and n–π* electronic transitions. Finally, QTAIM topological analysis showed that inter-molecular hydrogen bonds have a key role in the formation of arginine derivatives.

Compounds that contain an indole cycle in their structure have biological activity and are a source for the development of new medicinal products. N-acetyl-3-indolinones are actively used as incoming substance for their organic synthesis. Preparative methods for the obtaining of N-acetyl-3-indolinones, used as incoming substances for the synthesis of condensed indole derivatives with high therapeutic activity, have been developed. Synthesis of N-acetyl-3-indolinone was performed by deacetylation and cyclization of N-(2-carboxyphenyl) glycine and its 4-bromo-derivative to form N,O-diacetylindoxyls followed by hydrolysis of the obtained compounds to target indolinones. It was established that brominated derivatives have increased stability as compared with the analogues which do not contain bromine on the benzene ring of the indole nucleus, resulting in the increase in the yield of desired products in the reaction.

The synthesis of L-ornithine L-aspartate that involved basic hydrolysis of L-arginine by barium hydroxide, precipitation of barium cations as barium carbonate, addition of L-aspartic acid, and direct precipitation of L-ornithine L-aspartate was described. The obtained compound could be used as a hepatoprotective drug.

Описан синтез L-орнитина L-аспартата, включающий щелочной гидролиз L-аргинина при действии бария гидроксида, осаждение катионов бария в виде карбоната, присоединение L-аспарагиновой кислоты и осаждение продукта реакции. Полученный продукт может быть использован в качестве активного вещества для лекарственного средства гепатопротекторного действия.

L-Ornithine plays an important role in metabolism. Ornithine in addition to arginine and citrulline is involved in the (Krebs) ornithine cycle, a cyclic enzymatic process of sequential transformations leading to the deactivation and elimination of toxic ammonia and urea synthesis in vivo in humans, animals, and also certain plant and microorganism species. L-Ornithine L-aspartate is the salt of L-aspartic acid and L-ornithine that is used as the substance for manufacturing the hepatoprotective drugs Hepatil (Poland) and Hepa-Merz (Germany). They are used to reduce the ammonia level in vivo upon manifestation of hepatic insufficiency. Liver diseases are very common among the population of developed countries. This is related to increased alcohol consumption, poor diet, diabetes mellitus, and the use of toxic medicines for treatment of certain diseases and is also a consequence of transmitted viral hepatitis. L-Ornithine base, which has limited stability, must be used to prepare L-ornithine L-aspartate. In industry, L-ornithine is prepared by enzymatic synthesis via the action of arginase on L-arginine or L-glutamic acid. For this, L-ornithine is usually isolated as the more stable sulfate or chloride salts. These salts are processed beforehand on strong-acid cation-exchange resins in order to isolate L-ornithine base, which is necessary for manufacture of the substance [1 – 3]. These processes are lengthy and costly. The problem of developing simple routes to L-ornithine through classical synthetic organic methods remains critical, despite biotechnology successes in the manufacture of this amino acid. Studies in which citrulline and ornithine were prepared via basic hydrolysis of arginine were reported [4, 5]. It was found that the hydrolysis occurred with the formation of racemic products if strong bases were used. The preparation of L-ornithine hydrochloride via basic hydrolysis of L-arginine hydrochloride using Ba(OH) 2 was described [5]. The barium cations were precipitated at the end of the process by adding H 2 SO 4 . The product was isolated as L-ornithine hydrochloride mixed with citrulline. The goal of the present work was to develop a simple method for preparing L-ornithine L-aspartate from L-arginine subjected to basic hydrolysis. A chemical scheme according to which L-ornithine L-aspartate was prepared in three main steps was developed: 1. Hydrolysis of L-arginine to form L-citrulline and conversion of it to L-ornithine via coupled deamination and decarboxylation reactions.

N-acetyl derivatives of L-glutamine, L-proline, and 4-hydroxy-L-proline were synthesized in aqueous solutions with acetic anhydride as the acetylating agent. The resulting compounds were used as medicinal substances.

N-acetyl derivatives of L-glutamine, L-proline, and 4-hydroxy-L-proline were synthesized in aqueous solutions with acetic anhydride as the acetylating agent. The resulting compounds were used as medicinal substances.

Methods of synthesis of N-acetylderivatives of α-Amino Acids (L-glutamine, L-proline and 4-hydroxy-L-proline) using acetic anhydride as an acetylating agent have been developed. N-acetyl-L-glutamine and N-acetyl-L-proline have been used as parent substances for the preparation of drugs.

Taurine (2-aminoethanesulfonic acid) has been synthesized via reaction of 2-aminoethylsulfuric acid (prepared from monoethanolamine and sulfuric acid) with sodium sulfite. The target compound was separated from the excess of sodium sulfite by extraction with conc. aqueous ammonia (25%).

The synthesis of iron(II) di-DL-aspartate is described. Tests on rabbits with a model of acute and chronic anemia showed that the administration of the synthesized compound led to an increase in the hemoglobin level and in the numbers of erythrocytes and thrombocytes.

A series of selenium-containing complex salts of L-lysine and L-arginine has been synthesized. Some physicochemical characteristics of selenium-containing amino acids are reported.

A series of selenium-containing complex salts of L-lysine and L-arginine have been synthesized. Some physicochemical characteristics of selenium-containing amino acids are reported.