Abstract

Mercury can exist in the environment as metal, as monovalent and divalent salts and as organomercurials, one of the most important of which is mercuric chloride (HgCl₂). It has been shown to induce oxidative stress in erythrocytes through the generation of free radicals and alteration of the cellular antioxidant defense system. The effect of simultaneous pretreatment with vitamins C and E on the toxicity of HgCl₂ in human erythrocytes was evaluated. We examined the effect of several different doses of HgCl₂ (1.052, 5.262, 10.524 μM), or HgCl₂ in combination with vitamin C (VC; 10 μM) and vitamin E (VE; 30 μM), on the levels of malondialdehyde (MDA) and superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities in human erythrocytes in vitro. Erythrocytes were incubated under various treatment conditions (HgCl₂ alone, vitamins alone, or HgCl₂ plus vitamin) at 37°C for 60 min and the levels of MDA and SOD, CAT and GPx activities, were determined. Treatment with HgCl₂ alone increased the levels of MDA and decreased SOD, CAT and GPx activities in erythrocytes (P < 0.05). VC and VE-pretreated erythrocytes showed a significant protection aganist the cytotoxic effects induced by HgCl₂ on the studied parameters. There were no statistical differences among VC+VE-treated erythrocytes, as compared to non-treated control cells. These results indicated that the presence of vitamins at concentrations that are similar to the levels found in plasma could be able to ameliorate HgCl₂-induced oxidative stress by decreasing lipid peroxidation and altering antioxidant defense system in erythrocytes.

Key words: Mercury chloride, vitamins C and E, oxidative stress, erythrocytes, in vitro.