A novel glutathione-S-transferase-based biosensor for pyrethroid insecticides: From inhibition study to detection

Abstract

In this study, the inhibitory potential of four pyrethroid compounds on glutathione S-transferase (GST) by using molecular docking and in vitro assays was evaluated. Docking simulations of the pyrethroid ligands (bifenthrin, deltamethrin, lambda-cyhalothrin and tetramethrin) on the active site of GST were performed using Molegro Virtual Docker-MVD, according to the re-docking protocol. All tested compounds had a negative binding energy corresponding to a MolDock score ranging from -100.9 to -84.6. In the colorimetric in vitro assays, inhibition constants, Ki, varying from 0.29 to 20.0 µmol L−1 and IC50 values varying from 1.3 to 3.3 mg L−1 were obtained. These preliminary results indicated the great affinity of the selected compounds to the catalytic site of the GST enzyme, allowing thus the development of a GST-based screen-printed electrochemical biosensor modified with Meldola's blue-Reinecke's salt (MBRS) mediator. High sensitivity (LOD of 0.9, 1.6, 3.6 and 9.5 μg L−1, for tetramethrin, bifenthrin, λ-cyhalothrin, and deltamethrin, respectively), and also good accuracy (recoveries into the acceptable range) were observed for the selected pesticides. The electrochemical device developed herein proved to be suitable for assessing pyrethroid compounds in water and agricultural crops, and displayed good reproducibility and stability over time.

Keywords

• Pyrethroid insecticides
• GST inhibition
• Molecular docking
• Novel GST-based biosensor