THE EFFECTS OF THE PLANT GROWTH REGULATORS ON ANTIOXIDANT ENZYMES

This study describes in vitro the effect of three plant growth regulators (PGRs) such as mepiquat chloride, beta-naphthoxyacetic acid and gibberellic acid on the human blood antioxidant enzyme activites of glucose-6-phosphate dehydrogenase, glutathione peroxidase, glutathione reductase, glutathione S-transferase, catalase and superoxide dismutase. Enzyme activities have determined spectrophotometrically. PGRs have different effects on antioxidant enzyme activities. I-50 values of PGRs on antioxidant enzymes were determined by means of PGR concentration-activity % graph. The activities of antioxidant enzymes were changed by different concentrations of PGRs. PGRs behaved as an inhibitor on the antioxidant enzymes. The inhibition power of PGRs was different from enzyme to enzyme. The most power inhibitor for all enzymes studied was gibberellic acid, followed by beta-naphthoxyacetic acid and mepiquat chloride. When I-50 values compared with the results of metal ions in literature, PGRs had more inhibition powder than the metal ions. PGR toxicity caused a significant decrease in the antioxidant enzyme activity.