Biomaterial Database

Modification of methylmercury toxicity and metabolism by selenium and vitamin E: possible mechanisms. 1978

H E Ganther

Selenium and vitamin E exert powerful effects in reducing acute or chronic methylmercury toxicity. Levels of selenium normally found in foods (below 1 ppm) delay the onset of toxic signs caused by much higher levels of methylmercury. Tissue levels of mercury in selenium-supplemented animals equal or exceed those found in animals given methylmercury alone. Selenium does not appear to act by simply modifying intake, absorption, excretion, or distribution of methylmercury, and direct effects of both selenium and vitamin E have been observed in vitro when methylmercury was added to cultured nervous tissue cells. The only established functions for selenium and vitamin E in animals are related to the prevention of oxidative damage in tissues. To encompass the protective effects of selenium and vitamin E and to explain other toxicological aspects of methylmercury and other alkylmetals, a new hypothesis is proposed: The toxicity of the alkylmetals is not caused soley by the intact molecule, but also involves free radicals formed by homolytic fission of the carbon-metal bond.

UI	MeSH Term	Description	Entries
D008767	Methylmercury Compounds	Organic compounds in which mercury is attached to a methyl group.	Methyl Mercury Compounds,Compounds, Methyl Mercury,Compounds, Methylmercury,Mercury Compounds, Methyl
D005609	Free Radicals	Highly reactive molecules with an unsatisfied electron valence pair. Free radicals are produced in both normal and pathological processes. Free radicals include reactive oxygen and nitrogen species (RONS). They are proven or suspected agents of tissue damage in a wide variety of circumstances including radiation, damage from environment chemicals, and aging. Natural and pharmacological prevention of free radical damage is being actively investigated.	Free Radical
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D012643	Selenium	An element with the atomic symbol Se, atomic number 34, and atomic weight 78.97. It is an essential micronutrient for mammals and other animals but is toxic in large amounts. Selenium protects intracellular structures against oxidative damage. It is an essential component of GLUTATHIONE PEROXIDASE.	Selenium-80,Selenium 80
D014810	Vitamin E	A generic descriptor for all TOCOPHEROLS and TOCOTRIENOLS that exhibit ALPHA-TOCOPHEROL activity. By virtue of the phenolic hydrogen on the 2H-1-benzopyran-6-ol nucleus, these compounds exhibit varying degree of antioxidant activity, depending on the site and number of methyl groups and the type of ISOPRENOIDS.