Key words: subcritical water, extracts of Ginkgo biloba leaves (Ginkgo biloba L.), polyphenols, flavonoids, inhibitory AChE-activity, Alzheimer’s disease
The extracts of Ginkgo biloba (GB) leaves obtained in a medium of subcritical water (SBW) in the temperature range of 100 °C—220 °C were studied for the first time in order to assess the prospects for the use of GB leaf extracts for the prevention and treatment of neurodegenerative disorders, such as, for example, Alzheimer’s disease. The relationship of the activity of inhibition of the enzyme acetylcholinesterase (AChE) with the content of polyphenols and flavonoids was studied. The inhibitory activity of GB leafn extracts was expressed as IC50 values (an extract concentration that inhibits the AChE enzyme by 50 %), determined by dose-effect curves. It is shown that the content of polyphenols and flavonoids in the extracts obtained, and the inhibition activity of AChE extracts depends on the extraction method: if the traditional aqueous-ethanol extract has an anti-AChE-activity of IC50 = 3.57 mg/ml, then SBW- extracts are more effective inhibitors of AChE. At the same time, the maximum inhibitory activity of AChE, in a number of extracts obtained, was demonstrated by an extract obtained in the medium of SBW at 220 °C (IC50 = 0.74 mg/ml). At the same time, the AChE-activity of the obtained extracts of GB leaves correlates with the quantitative content of the sum of polyphenols and flavonoids, respectively. The total content of polyphenol (the sum of polyphenols per gallic acid or rutin) was highest in the extract obtained in medium of SBW at 220 °C, whereas the extract obtained at 100 °C in SBW was the lowest in content of polyphenols. The total content of flavonoids (in terms of rutin) was highest in extracts obtained in medium of SBW at 200—220 °C (24.6 mg equivalent to rutin/g dry weight of raw materials), and the lowest content in GB leaf extract obtained in SBW at 120 °C (10.6 mg rutin equivalent/g dry weight).
doi:10.34984/SCFTP.2021.16.4.007