Inhibitory effects of selected pesticides on peroxidases purified by affinity chromatography

The objective of this study was to determine the in vitro inhibition effects of seven commonly used pesticides including 2,4-d-acid dimethylamine, fenoxaprop-p-ethyl, glyphosate isopropylamine, haloxyfop-p-methyl, cypermethrin, λ-cyhalothrin, and dichlorvos on the peroxidase purified from turnip (Brassica rapa L.) and black radish (Raphanus sativus L.) using 4-amino benzohydrazide affinity column chromatography. The purification factors for the turnip and black radish peroxidases were found to be 263.29-fold (with a yield of 12.89%) and 36.20-fold (with a yield of 6.90%), respectively. Among these compounds, λ-cyhalothrin showed the strongest inhibitory effect against turnip peroxidase (Ki: 1.23 × 10−2 ± 0.21 × 10−2 mM) as noncompetitive inhibition. On the other hand, cypermethrin demonstrated the highest inhibition effect against black radish peroxidase (Ki: 2.14 × 10−2 ± 0.08 × 10−2 mM) as competitive inhibition.