Study of the Composition and Anti-Acetylcholinesterase Activity of Olive Leaf (Olea europea L.) Extracts Obtained in Subcritical Water

The paper presents a study of the content of secondary plant metabolites (the total amount of polyphenolic compounds and flavonoids) obtained in subcritical water (SubCW) and by traditional extraction in a water-alcohol mixture from olive (Olea europaea L.) leaves. Their anti-acetylcholinesterase (anti-AChE) activity is characterized by determining the IC50 value-the concentration of olive leaf extracts causing 50% inhibition of the acetylcholinesterase (AChE) enzyme activity. It is shown that the content of polyphenolic compounds and anti-AChE activity of the extracts depend on the extraction method applied. The SubCW extract obtained at 220 degrees C from olive leaves contains the maximum amount of polyphenolic compounds and demonstrates the highest anti-AChE activity (IC50 = 0.4 mg/mL). The lowest activity in terms of the AChE enzyme inhibition is found in the extract obtained by traditional water-alcohol extraction (IC50 = 3.6 mg/mL). The results show the promise of subcritical water in preparation of extracts with a high content of polyphenols for the development of pharmaceutical products and food additives for the prevention and treatment of various neurodegenerative diseases, such as Alzheimer's disease, from olive oil waste (olive leaves).