Studies on Paraoxonase-1 Isolated from Amniotic Fluid and its Effect Against Cisplatin-Induced Hepatotoxicity and Cardiotoxicity in Rats

Paraoxonase-1 (PON1) was isolated from the amniotic fluid of normal pregnancies at last week of gestation. One proteinous band had been isolated by gel filtration sephadex )G-50) from the protein precipitate produced by ammonium sulfate saturation (67%) after dialysis. The product from (G-50) gave two bands by sephadex (G-100). It was found that the first peak (Peak A) had higher activity for (PON1). The apparent molecular weights of the isolated PON1 using gel filtration chromatography and SDS-PAGE was (43873 + 350) and (43682 + 278) Dalton respectively. The results also showed that the optimum conditions of PON1 was obtained at (80 µg/ml) of protein as a source of the enzyme using (10 mmol/l) of paraoxon as a substrate, Tris-HCl buffer (0.14 mol/l) as a buffer at pH (8.0) and incubation for (7) minutes at (45C). Using lineweaver–Burk plot, the values of maximum velocity (Vmax) and Michaelis constant (Km) were (80.0 µmol/ min) and (3.79 mmol/l) respectively. The protective effect of PON1 against cisplatin-induced hepatotoxicity and cardiotoxicity by intraperitoneal injection of (10mg/kg) cisplatin were evaluated in 35 male albino white rats classified into 5 groups. The rats were treated with 0.5mg/kg/day or 1mg/kg/day of isolated PON1 injected intraperitonealy for 5 successive days before and 5 successive days after induction of toxicity. The results showed a significant reduction in the levels of alkaline phosphatase (ALP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), creatine kinase (CK), total bilirubin(TB) and malondialdehyde(MDA) in comparison with the cisplatin treated animals. It was concluded that (PON1) protects the liver and heart against the toxicity induced by this cytotoxic drug.