Antioxidant and prooxidant effects of ascorbate during iron-induced carbonyl formation in serum albumin

The aim of this study is to assess antioxidative and pro-oxidative efficacy of ascorbate on serum albumin during iron-induced oxidative stress. In this experimental study, albumin was placed in the oxidative system containing iron ions and different concentrations of ascorbate. To monitor albumin degradation, sodium dodecyl sulfate polyacrylamide gel electrophoresis was performed according to Laemmli procedure. Oxidative modification of albumin was demonstrated using a method for determination of carbonyl groups by 2,4-dinitrophenylhydrazine. By applying the carbonyl assay, ascorbate showed a dual effect: initial pro-oxidative effect on albumin changed to an antioxidant one in a dose-dependent manner. Our findings showed prooxidant effects for ascorbate in low concentrations (0-100 µM) and antioxidant effects in higher concentrations (100-300 µM). Also, electrophoretic pattern of plasma proteins showed significant protein aggregations in the range of 35 to 45 kDa of MW and protein degradations in the range of 115 to 180 kDa. Ascorbate can produce reactive oxygen species and can also inhibit the production of these oxidants in the presence of iron ions as well. These findings may be directly applicable to oxidative states during the administration of ascorbate and may be important in preventing oxidative modifications of proteins in blood circulation and other biological fluids.