Effects of Buffer Solutions and Chelators on the Generation of Hydroxyl Radical and the Lipid Peroxidation in the Fenton Reaction System.

Abstract

Oxygen free radicals, in particular the hydroxyl radical (·OH), which is readily formed by the Fenton reaction, are known to initiate lipid peroxidation. In this study the effects of several buffer solutions and chelators on the generation of ·OH and lipid peroxidation were examined. The generation of ·OH was decreased significantly in phosphate buffer solution, and slightly in Tris-HCl buffer solution, compared to that in HEPES or MOPS buffer solution, both of which have low affinity for iron ions. Phosphate and Tris-HCl buffer solutions also decreased the formation of lipid peroxides. The generation of ·OH varied by the addition of several kinds of chelators at different ratios of chelator/Fe(II), 1/10-10/1. And conflicting effects of EDTA or diethylenetriamine pentaacetic acid (DETAPAC) were observed in HEPES buffer and in phosphate buffer. At the concentration ratios of chelator/Fe(II) at which EDTA or DETAPAC inhibited ·OH generation in HEPES buffer, ·OH generation was promoted by EDTA or DETAPAC in phosphate buffer. On the other hand ADP slightly enhanced ·OH generation at the ratios of ADP/Fe(II) of 5/1 and 10/1 in HEPES buffer, but did not affect ·OH generation in phosphate buffer. Lipid peroxidation was completely inhibited by the addition of DETAPAC and EDTA, while ADP promoted ·OH generation at the chelator/Fe(II) ratios of 5/1 and 10/1.