In Vitro Effects of Dexamethasone on Human Serum Paraoxonase-I PON1 Activity

Abstract

Dexamethasone has successfully been used for treatment of some inflammatory diseases. Here, we evaluated the in vitro effects of dexamethasone on the activity of human serum paraoxonase hPON1 . PON1 enzyme was purified using simple chromatographic methods: DEAE-Sephadex anion exchanger and Sephadex G 200 gel filtration chromatography from human serum. hPON1 was purified approx. 225-fold with a final specific activity of 4867.3 U x mg-1 proteins and with a purity up to 39.8%. Dexamethasone dose-dependently decreased in vitro hPON1 activity. IC50 value for dexamethasone was determined as 1.106. Inhibition constant Ki was estimated as 3.284 ± 0.394 mM from Lineweaver-Burk graph. Inhibition type of dexamethasone was determined as noncompetitive. Our results show that dexamethasone inhibits hPON1 activity under in vitro conditions.