Comparative efficiency of antioxidants upon the protection of bacterial plasma membrane from active forms of oxygen

The effect of hydroxyl radicals OH. generated by the decomposition of H2O2 by Fe2+ ions (Fenton reaction) on the barrier properties of plasma membrane s of Escherichia coli cells K-12 was studied by electroorientation spectros copy. It was found that the administration of hydrogen peroxide led to the disturbance of the barrier properties of plasma membranes only when the cel ls were preincubated with Fe2+ ions and their constant concentration in the system was maintained by ascorbate or dithiotreitol (150-500 muM) The exte nt of the toxic action on plasma membranes depended on the concentration of reacting elements and the substance used as a reducer Fe2+. The efficiency of protection of antioxidants of different classes (enzymic, SH-containing , and phenolic compounds) against the toxic action of hydroxyl radicals on plasmatic membranes was shown.