Inhibitory effects and molecular interaction analysis of emergency cardiac drugs on human serum paraoxonase 1: an integrated <i>in vitro</i> and <i>in silico</i> approach

<b>Context</b>: Paraoxonase 1 (PON1) is a crucial antioxidant enzyme involved in the hydrolysis of organophosphates and the prevention of oxidative damage to lipoproteins. <b>Objective</b>: This study aimed to purify PON1 using a newly synthesised hydrophobic interaction chromatography gel and to investigate the inhibitory effects of selected emergency cardiac drugs on PON1 activity through in vitro and in silico approaches. <b>Materials and methods</b>: PON1 was purified using a Sepharose-4B-L-tyrosine-6-aminochrysene hydrophobic interaction chromatography gel. The inhibitory effects of deslanoside, digitoxin, esmolol, and adenosine were evaluated via kinetic inhibition assays, molecular docking, molecular dynamics simulations, and MMPBSA calculations. <b>Results</b>: Among the tested compounds, esmolol exhibited the strongest inhibition of PON1 activity (IC₅₀ = 0.131 ± 0.071 μM, <i>K_i</i> = 0.044 ± 0.009 μM) via a competitive mechanism. Molecular docking revealed strong binding affinity of esmolol to the PON1 active site, which was further supported by molecular dynamics simulations over 150 ns. <b>Discussion and conclusion</b>: The findings indicate a potential interaction between commonly used emergency cardiac drugs and PON1, highlighting the importance of evaluating off-target effects on critical metabolic enzymes in cardiovascular therapy.