Background. The oxygen is the ultimate electron acceptor in the electron flow system that produces energy. Problems appears when the electron flow becomes uncoupled thus, generating free radicals. While the majority of processes require oxygen, the last is a highly reactive molecule that can damage cells by producing reactive oxygen species, such as hydroxyl radical, superoxide radical, hydrogen peroxide and hypochlorous acid, all together defined as triggers of oxidative stress. The last is involved in many types of pathologies, such as cancer, atherosclerosis and rheumatic arthritis. Antioxidants can stop formation of free radical by giving hydrogen atoms or scavenging them. The antioxidant can be defined any molecule capable of preventing or blocking oxidation of lipids, proteins and nucleic acids. The reduced glutathione (GSH), as well enzymes, glutathione peroxidase (GPO), glutathione reductase (GR) and glutathione S-transferase (GST) represent antioxidants which prevent the formation of new free radicals, converting them into less harmful molecules. The present study was conducted to assess the antioxidant activity of Taraxacum officinale (TO) ethanolic extracts with different bioactive contents. This experiment was conducted with extracts prepared from dandelion (Taraxacum officinale F. H. Wigg) leaves. A series (10%, 20%, 25%, 40%, 50% and 80%) of ethanolic extracts were made. The influence of TO extracts on RBC’s GPO, GR, GST, glutathione (GSSG, GSH and total-GSH) and thiols (native and total) was evaluated by measuring absorbance spectrophotometrically. Conclusions. Taraxacum officinale ethanolic extracts exhibit a strong antioxidant activity. This plant is capable of preventing damage of cells during oxidative stress process, by using different targets of glutathione system. But, this activity depends of ethanol concentrations, maybe due to different bioactive content.

The administration of new Schiff heterocyclic bases and their copper (II) complexes, thiosemicarbazide derivatives induces various influences on the activity of glutathione-dependent enzymes in splenic tissue. The selective action of the studied compounds on the expression of glutathione enzymes is evident, which is manifested by a tendency of insignificant decrease of glutathione reductase (GR) and glutathione peroxidase (GPO), insignificant increase of glutathione-S-transferase (GST) and marked depression of glutaredoxin levels. The slight increase of GST under the action of the studied compounds can be considered as a protective reaction aimed at stagnating the intensity of peroxide processes and supporting the activity of the glutathione cycle, and decreased the activity of glutaredoxin denotes their antiproliferative, cytostatic effect. Further studies are needed to evaluate the mechanisms of action of the investigated compounds on the activity of glutathione-dependent enzymes in other biosystems and animal experiments, to assess the practical importance of the obtained results.

Background: Currently, there is a growing interest in new copper (Cu2+) heterocyclic coordination compounds (CC), isothiosemicarbazide derivates, which demonstrated multiple beneficial properties, but their effect on reactions with free radicals such as the superoxide radical has not been investigated. Material and methods: The action of new micromolecular complexes of copper (Cu2+) chloride and bromide with methyl n- (prop-2-en-1-yl) -2- (pyridin2-ylmethylidene) hydrazine carbimidothioate on capturing activity of the superoxide radical was determined by the spectrophotometric method in vitro experiments. Results: It was established that the micromolecular complexes of copper (II) chloride and bromide with methyl n-(prop-2-en-1-yl)-2-(pyridin-2- ylmethylidene) hydrazine carbimidothioate have been found to possess strong superoxide radical inhibitor properties when interacting with a superoxide radical. In addition to this, the IC50 of the studied compounds depends on the nature of the acid-ligand in the internal sphere of the complex and increases in the following sequence: Cl- –Br- . Conclusions: The established property of mentioned compounds is new, because their use as micromolecular inhibitors of superoxide radicals has not been described so far. The synthesized CC expand the arsenal of superoxide radical inhibitors with high biological activity. Their possible significance for the development of new treatment strategies for diseases associated with the overproduction of superoxide radicals is discussed.

Introduction. Identification, study and testing of new remedies for treatment approaches of diseases, resulting from imbalance between oxidants and antioxidants in favor of oxidants, with potentially destructive potential and pathogenesis in liver disorders is of particular interest due to the increase in incidence and severity of these pathologies. Material and methods. The action of novel local copper coordination compounds, thiosemicarbazide derivatives - CMD-4, CMJ-33 and CMT-67, was evaluated in experiments on white rats after subcutaneous administration in two different doses (0.1 and 1.0 µM/kg) 3 times a week for 30 days. The main indices of oxidative stress were evaluated: the level of malonic dialdehyde (MDA), nitric oxide derivatives (NO), S-nitrosothiols, advanced glycation end products (AGEs), advanced oxidation protein products (AOPP) and ischemia-modified proteins (IMP), and antioxidant system: - superoxidismutase (SOD) and catalase activity (CAT), the level of histidine (His) and total antioxidant activity (TAA) in liver tissue of white rats. Results. The administration of CC resulted in the reduction of oxidative stress indices - MDA, AGEs and S-nitrosothiols, which denotes the antioxidant effect of the studied compounds. The level of NO and AOPP derivatives does not change substantially. When administering CMD-4 (1 µM/kg), SOD activity and catalase function decreased markedly. Changes in the content of His and TAA have been shown to be inconclusive, maintaining within the limits of the values recorded in the control group. Conclusions. The elucidation of the modifications of the free radicals processes in liver tissues, which are the basis of the CC action, broadens the theoretical knowledge about the biological properties of a number of chemical compounds; as well provide new possibilities to explore perspective objects in order to obtain new efficient drug preparations

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