Comparative Methylation Chemistry of Platinum,Palladium,Lead,and Manganese.

摘要

A study was carried out to evaluate the potential for platinum,palladium,lead,and manganese salts and oxides to be biochemically methylated. Methylation is an important,well recognized,determinant of metal toxicity;the striking example being the extreme health hazard of methylated mercury. The possible biological methylation of the metals which are associated with emissions arising from the use of automotive fuels,fuel additives,and catalytic control devices is of special concern to the Environmental Protection Agency's Catalyst Research Program. Salts of platinum,palladium,and lead,and oxides of lead all containing the metal in a +4valence were observed to demethylate methylcobalamin, a biologically active form of vitamin B-12. Inorganic salts and oxides of manganese were unreactive. No evidence for a stable monomethyl-metal derivative was found using palladium and lead compounds as reactants. However,salts of platinum +4do result in the formation of stable methylation products. The reaction product formed from methylcobalamin and hexachloroplatinate was shown definitively to be a monomethyl-platinum compound. It is sufficiently stable in aqueous solutions under a variety of conditions to exist in freshwater ecosystems and to exhibit toxic effects on mammalian cells.