SUBCRITICAL WATER AS A TOOL FOR OBTAINING PRODUCTS WITH HIGH ANTIOXIDANT ACTIVITY FROM PRODUCTION WASTE ON THE EXAMPLE OF OLIVE LEAVES (OLEA EUROPAEA L.)

Abstract

Recently, “green chemistry” methods have been increasingly used to process agricultural waste in order to obtain products with high added value. In the presented work, the medium of subcritical water (SBW) was used to obtain (in the temperature range from 100 to 220 °C) extracts from the leaves of the olive (LO) of Olea europaea L. enriched with polyphenols and to assess their antioxidant activity (AOA). The use of medium of SBW for extraction processes allows not only to increase the extraction of secondary plant metabolites (SPM) from the plant matrix, but also to achieve a change in the phytochemical profile of extracts obtained in SBW. The dependence of the content of secondary plant metabolites (the sum of polyphenolic compounds and flavonoids) and AOA of extracts obtained at different temperatures in SBW and traditional aqueous-alcoholic extraction from olive leaves was studied. It was shown that the content of polyphenolic compounds and the AOA activity of the extracts depend on the extraction conditions. It has been demonstrated that the obtained extract from LO in medium of SBW at 220 °C contains the maximum amount of polyphenolic compounds and demonstrates the maximum AOA (EC50=26.9 μg/ml). The presented results demonstrate the promise of using SBW for obtaining extracts from LO with a high content of polyphenols for the development of pharmaceuticals and food additives with high AOA.