INFLUENCE OF PRESERVATION METHOD ON ANTIOXIDANT POTENTIAL OF EXTRACTS BASED ON ARONIA MELANOCARPA FRUITS

Background. To study the antioxidant properties of plant extracts, photometric and luminescent methods of analysis are most often used in practice, despite their inherent shortcomings. It was of interest to investigate the prospects of using an electrochemical method for assessing the antioxidant activity of phytoextracts - coulometric titration with electrogenerated bromine, as well as a biological method rarely used in practice - the biotesting method. This will make it possible not only to assess the consistency of the results on the antioxidant potential of the studied phytoextracts obtained by various methods of analysis, but also to answer the question about the ratio of water-soluble and water-insoluble biologically active substances with antioxidant activity in a given plant material. Purpose. The purpose of the work was to assess the antioxidant potential of aqueous and alcoholic extracts based on natural, frozen and dried chokeberry fruits (Aronia melanocarpa). Materials and methods. The object of the study is aqueous and ethanol extracts based on freshly picked, dried and frozen fruits of chokeberry (Aronia melanocarpa) variety "Chernookaya", which is one of the most common large-fruited varieties characterized by high yield and frost resistance. The fruits of the studied chokeberry variety were collected during the ripening period (end of August-September) on the territory of the Republic of Tatarstan Zelenodolsk region (garden plot). Phytoextracts were obtained by single maceration with stirring using distilled water and 96% ethanol as extractants. The integrated antioxidant activity of aqueous and ethanol extracts was measured by coulometric titration with electrogenerated bromine, using rutin as a standard. Antiradical activity was determined by a colorimetric method using the 2,2-diphenyl-1-picrylhydrazyl reagent. During biotesting, the stimulating or inhibitory effect of the studied phytoextracts on a biological model (Paramecium caudatum) was assessed by determining its stress resistance to hydrogen peroxide. Results. The conducted studies showed good agreement between the experimental results obtained by the methods of biotesting and coulometric titration with electrogenerated bromine, which confirmed the promise and feasibility of using the latter to evaluate the antioxidant activity of phytoextracts. The fruits of chokeberry, growing on the territory of the Republic of Tatarstan, are characterized by high antioxidant properties. At the same time, the antioxidant potential of alcoholic extracts is significantly higher than aqueous extracts, on average by 15.5%, which is probably due to the higher content of antioxidants of various natures soluble in ethanol. The study of the antiradical properties of the extracts under study revealed a slight excess of the antiradical characteristics of aqueous phytoextracts compared to alcoholic ones. The tendency of increasing stress resistance of paramecium with increasing concentration of extracts, in the range of the latter from 0.036 to 0.07 mg/ml, is more pronounced for aqueous extracts characterized by higher anti-radical activity. Conclusion. Thus, the results obtained confirm the high antioxidant potential of chokeberry fruits growing on the territory of the Republic of Tatarstan, as well as the preference for freezing the studied phytoraw materials as a promising method of preservation for the targeted production of aqueous biologically active preparations.