Inhibition of Plant Growth Regulators on Paraoxonase Activity

Abstract

The purpose of this study was to investigate the in vitro effects of four commonly used plant growth regulators (PGRs) (indole-3-acetic acid, indole-3-butyric acid, gibberellic acid and kinetin) on human serum paraoxonase (PON). Serum paraoxonase is an esterase that plays a key role in organophosphate detoxification and in prevention of atherosclerosis. Serum paraoxonase from humans was purified using ammonium sulfate precipitation and Sepharose-4B-L-tyrosine-1-napthylamine hydrophobic gel. IC50 values of the chemicals that cause inhibition were determined by means of activity percentage diagrams. The plant growth regulators used in this study affected the PON activity from human serum to various degrees. The concentrations of indole-3-acetic acid, indole-3-butyric acid and gibberellic acid that inhibited 50% of the enzymatic activity were 63.86 mu M, 45.48 mu M and 14.4mM, respectively. Conversely, the enzyme activity was increased by kinetin.