Cadmium Mobilization by Monoaralkyl- and Monoalkyl Esters of meso-2,3-Dimercaptosuccinic Acid and by a Dithiocarbamate

Syntheses and relative cadmium mobilizing properties are described for three new monoaralkyl esters (HOOCCH(SH)CH(SH)COOR, where R = phenylethyl ((CH₂)₂C₆H₅), MPhEDMS; R = 3-phenylpropyl ((CH₂)₃C₆H₅), MPhPDMS; and R = 2-phenoxyethyl ((CH₂)₂OC₆H₅), MPhOEDMS) of meso-2,3-dimercaptusuccinic acid. These were prepared by the reaction of the corresponding alcohol with meso-2,3-dimercaptosuccinic acid (DMSA) in aqueous HCl. When administered intraperitoneally to cadmium-loaded mice at 0.50 mmol/kg/day for four consecutive days, all induced significant reductions in the whole body cadmium levels. MPhEDMS, 60%; MPhPDMS, 66%; and MPhOEDMS, 58% in comparison with control levels. At the same dosage monoisoamyl meso-2,3-dimercaptosuccinate (Mi-ADMS) and a dithiocarbamate, sodium N-benzyl-4-O-(β-D-galactopyranosyl)-d -glucamine-N-carbodithioate (BLDTC) induced reductions of 65% and 57%, respectively. Hepatic and renal cadmium were also depleted significantly, while brain cadmium levels were unchanged. These compounds induced a significant reduction in the cadmium levels of the spleen, and one, MPhOEDMS, produced a 10% decrease in pancreatic cadmium. The manner in which the later injections removed smaller fractions of the total body cadmium is consistent with a bodily distribution of these compounds by which they are concentrated primarily in the kidneys and the liver, with much smaller amounts reaching other organs. It is proposed that these compounds enter renal and hepatic cells through an anion transport system.