CHELATORS OF IRON IONS - DESFEROXAMINE AN D EDTA INHIBIT HYPOCHLORITE-INDUCED PEROXIDATION OF PHOSPHATIDILCHOLINE LIPOSOMES BY SCAVANGING OF HOCL OCL-/

The aim of the present paper was to study the influence of Iron ions c helators desferoxamine (DF) and EDTA on lipid peroxidation in egg yolk phosphatidylcholine liposomes induced by sodium hypochlorite (NaOCl). Lipid peroxidation products, as detected by 2-thiobarbituric acid rea ction, were accumulated in liposomes under incubation with NaOCl. Thei r accumulation was inhibited by DF and EDTA. 50% inhibition occurs at 2,5 mu M and 20 CIM of DF and EDTA, respectively. These values are 20- and 2,5-limes lower than NaOCl concentration. However, the chelation of contaminating Iron seems not cause these effects because the yield of peroxidation products was not changed by Fe2+ or Fe3+ previously ad ded to incubation medium. It was shown gy UV spectrophotometry that Na OCl directly interacts with DF and EDTA dissolved in 145 mM NaCl, 10 m M phosphate (pH 7,4) at molar ratios of approximately 10:1 and 2:1 wit h rate constants of 150 +/- 10 M(-1) s(-1) and 120 +/- 40 M(-1)s(-1), respectively. Unstable intermediates with a maximum absorption at 2;0 nm were formed. They were further converted with rate constants of 1,8 +/- 0,5 h(-1) and 2,3 +/- 0,6 h(-1). Our results reveal that both DF and EDTA are able to react with NaOCl at molar ratios higher than the equimolar ratio inhibiting NaOCl-induced lipid peroxidation.