RESUMO
BACKGROUND/AIMS: Bovine milk whey, which mainly includes beta-lactoglobulin (58%), alpha-lactalbumin (22%) and immunoglobulin G (IgG; 11%), is a source of a wide range of proteins with a useful nutritional and physiological function. We previously demonstrated antiperoxidative effects of whey-derived alpha-lactalbumin and beta-lactoglobulin in rats. The aim of the present study was to investigate the role of the IgG in antiperoxidative properties. METHODS: Four-week-old, male Sprague-Dawley rats were fed a vitamin E-deficient diet (control) or a diet supplemented with 2.5% of an IgG-rich fraction for 4 weeks. Different antiperoxidative parameters were measured in blood and liver from the rats. RESULTS: In comparison to the rats fed the control diet, those fed the IgG-containing diet were resistant to peroxidation stress. The IgG diet resulted in a decreased concentration of thiobarbituric acid-reactive substances in red blood cells (RBC) and plasma, and increased activities of catalase, superoxide dismutase and glutathione peroxidase in the RBC and liver. The plasma density (d) < 1.063 g/ml lipoproteins from the IgG group were more resistant against the induced lipid peroxidation. CONCLUSION: These results demonstrate antiperoxidative properties of IgG. The underlying mechanism(s) remain to be determined.