Chelation in Metal Intoxication XXV

β-1,2-Phenylene di-α-mercaptoacrylic acid (1,2-PDMA), β-1,4-phenylene di-α-mercaptoacrylic acid (1,4-PDMA) and α-mercapto-β- (2-hydroxyphenyl) acrylic acid (MHA) were synthesized and compared with 2,3-dimercaptopropane-1-sulfonate (DMPS) for their ability to counteract toxic effects of lead and nickel in rats. 1,2-PDMA and DMPS were most effective in enhancing the excretion of metals, restoring most of the metal induced biochemical alterations and reducing the body burden of the metals; These observations confirm that the chelating agents with two adjacent sulfhydryl groups are better than those with nonadjacent SH groups as metal antidotes. The success of MHA in mobilizing the tissue metals and increasing their urinary excretion indicates participation of the hydroxy group on the benzene nucleus besides the SH group of the MHA molecule, in chelation of the metals.