A new approach to develop a standardized method for assessment of acetylcholinesterase inhibitory activity of different extracts using HPTLC and image analysis

Abstract

A new, validated, sensitive and cheap method for preliminary quantitative evaluation of acetylcholine esterase inhibitory activity is presented. The proposed method combines HPTLC with data analysis by means of image processing software. An in-situ TLC autobiographic method was employed in which regions of the TLC plate which contain acetylcholinesterase inhibitors show up as white spots against the yellow background. Bleaching of the yellow color, caused by substances with acetylcholinesterase inhibitory activity was observed and recorded using a digital camera. ImageJ, JustTLC and Sorbfil, three image processing programs were evaluated for quantitative measurements. For evaluation of the assay efficiency, acetylcholinesterase inhibitory activity of different Amaryllidaceae plant extracts was expressed as Standard Activity Coefficients (SACs), which are relative measures of the activity to the well known acetylcholinesterase inhibitor eserine. We attempted to validate the method according to the ICH guideline. Different statistical data revealed that all image analysis software are able to detect the acetylcholine esterase inhibitory activity at very low concentration levels with the ImageJ program being the best of all three tested software regarding sensitivity, linearity and precision.

Keywords: Acetylcholinesterase inhibitory activity; Autobiography; HPTLC; Image processing software; Quantitative..