Evaluation of different extraction techniques for the assay of anti - acetylcholinesterase activity of olive leaves (Olea europaea)

Abstract

The total phenol content and the anti-acetylcholinesterase activity were compared in olive leaf (OL) extracts obtained using both subcritical water extraction (SbWE) and conventional solvent extraction (ethanol-water). The method proposed by Ellman (in vitro) was used to study the inhibitory activity of acetylcholinesterase (AChE). The total content of phenolic compounds and AChE activities of OL extracts varied depending on the used extraction method. Thus, the extract obtained using the subcritical water technique (220 °C) showed the highest amounts of total phenolic components, expressed as gallic acid equivalents, (70.4 mg/g raw material) and the highest inhibitory AChE-activity (IC50 = 0.35 mg/ml). The obtained values of the anti-AChE activity of the extracts of OL demonstrated that the inhibitory activity for SbW-extract 120 °C (IC50 = 2.92 mg/ml) and SbW-extract 180 °C (IC50 = 0.8 mg/ml) is higher than that of the traditional extract (IC50 = 3.6 mg/ml), respectively. These results indicate a great potential of the subcritical water technique to develop the techniques to produce commercial extracts of OL, and these results could encourage improved utilization of the OL. The collected data on the anti - acetylcholinesterase activity of olive leaves clearly demonstrate the prospects for use of OL extracts in the development of novel pharmaceutical substances and nutraceuticals for the prevention and/or the treatment of Alzheimer's disease as well as some other neurodegenerative diseases.