SUBCRITICAL WATER AS A TOOL FOR OBTAINING EXTRACTS OF SECONDARY PLANT METABOLITES WITH HIGH ANTIOXIDANT ACTIVITY FROM GINKGO BILOBA L. LEAVES

Abstract

Extracts of secondary plant metabolites (SPM) with high antioxidant activity (AOA) are gaining more and more attention as biologically active additives. To obtain them, methods of "green chemistry" are increasingly being considered. In the present work, to obtain extracts with high antioxidant activity enriched of polyphenols from the leaves of Ginkgo biloba (GB), medium of a subcritical water (SCW) was used in the temperature range from 100 to 220 °C. The use medium of the SCW for extraction processes allows not only to increase the extraction of SPM from the plant matrix, but also to achieve a change in the phytochemical profile of the obtained extracts.
 The polyphenol profile of extracts leaf’s GB was studied by UV/Vis spectrophotometry, as well as the dependence of the content of SPM, in the form of the sum of polyphenolic compounds (including flavonoids) and AOA of extracts, on the extraction method: in medium of SCW or water-alcohol (traditional) extraction. It has been shown that the content of polyphenolic compounds and the AOA of extracts depend on the extraction conditions (temperature of SCW). It was demonstrated that the extract obtained from leaves of GB in SCW at 220 °C contains the highest amount of polyphenolic compounds and demonstrates the maximum AOA (EC50=34.7 μg/ml) among the obtained extracts. The presented results demonstrate the promise of using SCW to obtain extracts from leaves of GB with a high content of polyphenols for the development of pharmaceuticals and food supplements with high AOA.