Association of human serum paraoxonase‐1 with some respiratory drugs

In this study, we investigated the effects of certain respiratory drugs, which are mainly used on human serum paraoxonase‐1 (hPON1; EC 3.1.8.1). hPON1 was purified from human serum, with 354.91 fold and 45% yield by using two simple step procedures including, first, ammonium sulfate precipitation, then, Sepharose‐4B‐l ‐tyrosine‐1‐naphthylamine hydrophobic interaction chromatography. SDS‐polyacrylamide gel electrophoresis showed a single protein band belonging to hPON1 with 43 kDa. All the pharmaceutical compounds inhibited the PON1 enzyme highly at the micromolar level. The obtained IC₅₀ values for nine different pharmaceutics ranged from 0.219 μM (salbutamol sulfate) to 67.205 μM (montelukast sodium). So, all drugs could be considered as potent hPON1 inhibitors. K_i values and inhibition types were determined by Lineweaver‐Burk graphs. While varenicline tartrate and moxifloxacin hydrochloride inhibited the enzyme in a noncompetitive manner, others inhibited it in a mixed manner.