Blood Erythrocytes—a Biological Model for Evaluating Antioxidant Activity of Chemical Compounds (A Review)

This review presents an analysis of literature, including our own work, on various aspects of using red blood cells (RBCs) as an in vitro model in the comprehensive evaluation of antioxidant activity of a wide range of natural and synthetic compounds, their mixtures, and plant extracts. The characteristics of the most commonly used initiators of oxidative stress in such studies, 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) and H2O2, as well as the mechanisms underlying the development of the hemolytic process are discussed. A critical analysis of methodological approaches to assessing the level of hemolysis is provided. The review further discusses the evaluation of erythrocyte survival under oxidative stress conditions and the ability of the tested compounds to act as membrane protectors. The review considers the criteria for a comprehensive assessment of erythrocytes, facilitating the study of cellular, and molecular mechanisms underlying antioxidant activity of a wide range of substances in a model of oxidative hemolysis of erythrocytes. Traditional methods include assessment of the intensity of membrane lipid peroxidation (LPO) processes through measurement of concentration of products that react with 2-thiobarbituric acid, as well assessment of relative content of oxidized forms of hemoglobin in erythrocytes. The use of modern fluorescent methods is another promising approach. In particular, the fluorescence of heme degradation products, the decrease in intensity of which can indicate antioxidant activity in the investigated compounds, is a sensitive marker of oxidative stress in erythrocytes. Another prominent fluorescent method is the assessment of oxidative stress level by measuring the intracellular concentration of ROS in erythrocytes. Analysis of our own and literature data allows us to recommend to use the method of oxidative hemolysis of erythrocytes to screen newly developed compounds in order to select the most interesting candidates for further in-depth studies. This method is appropriate for establishing the structure-activity relationship and developing a strategy for the targeted synthesis of new biologically active compounds combining high hemocompatibility and antioxidant activity, which are promising for biomedical applications.