Disposable Electrochemical Biosensor Based on Acetylcholinesterase for Inhibition Assays Using a Natural Substance and Plants Extracts

Abstract

In general, insects are considered pests in agricultural areas and their control is essential for the high productivity of cultivated areas. The control of these insects can be achieved by the inhibition of enzymes present in the insect´s organism. The enzyme acetylcholinesterase (AChE) is present in the neuromuscular junctions of vertebrates and invertebrates, and it is an important target for pest control. Herein, we present the development of a disposable electrochemical biosensor based on AChE (Bio-AChE) to rapidly evaluate the presence of new potential inhibitors in crude extract of plants. Bio-AChE was constructed by modifying disposable screen-printed carbon electrode (SPCE) with glutathione-decorated gold nanoparticles which AChE was covalently immobilized. Electrochemical studies confirm the effective immobilization of the enzyme, and the Bio-AChE was applied to assess the inhibitory activity of azadirachtin obtained from Azadirachta indica that is a well-know AChE inhibitor. The biosensor proposed showed excellent results demonstrating the inhibition activity of the azadirachtin against AChE. The crude extracts of Picramnia riedelli, Picramnia ciliata, and Toona ciliata were evaluated with the Bio-AChE and all showed values of percentage of inhibition of around 50%. The extracts were evaluated by 1H NMR spectra that identify classes of natural compounds that could be responsible for the inhibition activity. The disposable Bio-AChE proposed showed to be a reliable method for simple and rapid screening of new inhibitors in plant extracts opening an avenue for screening of new natural products with potential for pest control.