Possible Mechanism of Detoxifying Effect of Selenium on the Toxicity of Mercury Compounds

Abstract

Co-administration of selenium compounds with mercuric mercury resulted in remarkable depression of acute toxicity of mercury through 1) reduction of mercury accumulation in the kidneys, a major target of acute toxicity of inorganic mercury, by forming high molecular weight complexes consisting of Hg, Se and proteins in the blood, which were hardly filtered through glomerulus; 2) elongation of retention of mercury and selenium as inert high molecular weight complexes in the blood, especially in the erythrocytes; 3) formation of stable and non-diffusible complexes of Hg and Se in various organs such as the liver and kidneys.

Methylmercury was found to form a complex with selenium, bis(methylmercuric) selenide (BMS), in various tissues on concurrent administration with selenite. However, the reduction of methylmercury toxicity by selenium as reported in numerous papers seems to be hardly explainable by the formation of BMS which showed a relatively low stability in the blood and other tissues.

Using the assay methods developed in the studies described above to detect interactions between selenium and other metals, we indicated that more than 18 metal ions might be subjected to interactions with selenium in animal body, showing important roles of this essential metalloid as a modifying factor of metal toxicity. Although, according to the experimental data so far obtained, selenium appears not to be clinically applicable as an antidote for mercury intoxication, we could develop a possible application of selenium for reducing dose-limiting toxicity of cis-platinum, a platinum complex most widely used in cancer chemotherapy, without compromising its anti-tumor activity.