Chelation in metal intoxication. XIX. alpha-Mercapto-beta-aryl acrylic acid as antidotes to nickel and lead toxicity

Chelation in metal intoxication. XXXIV. Mixed ligand chelation in lead poisoning

The effectiveness of alpha-mercapto-beta-(2-furyl)acrylic acid (MFA) and N-benzyl-N-dithiocarboxy-D-glucamine (NaB), used in combination, in the mobilization and excretion of lead was investigated in rats. Male Wistar rats received 10 mg Pb/kg as lead acetate intragastrically daily for 6 weeks. The lead-exposed rats were treated with either MFA or NaB or both 200 mumol/kg i.p., each, daily for 3 days. Both chelating agents provoked significant urinary and faecal excretion and lowered the soft-organ lead burden. However, combined therapy did not elicit any additive or synergistic response.

Chelation in metal intoxication XXX: Alpha-mercapto-beta-aryl acrylic acids as antidotes to cadmium toxicity

alpha-Mercapto-beta-(2-furyl) acrylic acid (MFA), alpha-mercapto-beta-(2-hydroxyphenyl) acrylic acid (MHA), beta-1,2-phenylene di-alpha-mercaptoacrylic acid (1,2-PDMA) and beta-1,4-phenylene di-alpha-mercapto acrylic acid (1,4-PDMA) were compared to sodium N-benzyl-D-glucamine dithiocarbamate (NBG-DTC) an effective cadmium chelator, for their ability to mobilize Cd and influence the Cd induced tissue metallothionein (MT) in rats administered 109CdCl2, 72 hr earlier. MFA was almost as effective as NBG-DTC but more effective than MHA in enhancing urinary and faecal excretion of Cd, reducing tissue and blood levels of Cd and in lowering Cd induced increase in hepatic and renal MT contents. 1,2-PDMA and 1,4-PDMA were effective only in reducing the hepatic burden of Cd. The resuls do not indicate any direct relationship between the efficacy of alpha-mercapto-beta-aryl acrylic acids to decorporate body Cd and their lipophilic-hydrophilic character or number-arrangement of their sulfhydryl groups.

Influence of thiamine and ascorbic acid supplementation on the antidotal efficacy of thiol chelators in experimental lead intoxication

The influence of the administration of thiamine (vitamin B1), ascorbic acid (vitamin C) or their combination on the efficacy of two thiol metal chelators, viz. alpha-mercapto-beta-(2-furyl) acrylic acid (MFA) and 2,3-dimercaptosuccinic acid (DMS), in counteracting lead (Pb) toxicity was investigated in rats. Ascorbic acid or its combination with thiamine enhanced the urinary elimination of Pb, reduced the hepatic and renal burden of Pb, and reversed the Pb-induced inhibition of the activity of blood delta-aminolevulinic acid dehydratase (delta-ALA-D). All these effects were more evident in DMS- than in MFA-treated rats. The combination of MFA and DMS treatments further improved the performance of the animals in enhancing urinary Pb excretion and in reducing Pb hepatic levels.

Chelation in metal intoxication. XXVII: Chelating agents containing vicinal thioether groups as antidotes of lead toxicity

The chelating agents containing vicinal thioether groups viz. 4,5-dicarboxy-3,6-dithiaoctanedioic acid (DMSA), disodium-3,6-dithia - 1,8-octanediol-4,5 dicarboxylate (DMES) and 2,9 diamino- 5,6 dicarboxy-4,7 dithiadecanedioic acid (DCSA) were about equally effective but far more effective than pounds-mercapto- beta -(2-thienyl) acrylic acid (MTA) in enhancing excretion of lead, reversing certain Pb induced biochemical alterations and mobilizing tissue Pb in poisoned rats. The results indicate that vicinal thioether groups participate in chelation of Pb. However, none of them could decrease brain Pb. Owing to their water solubility, low toxicity and ability to chelate toxic metals, the chelators with vicinal thioether groups appear as promising antidotes of Pb intoxication.