Protective effects of N-acetylcysteine and its amide derivative against toxic metals in vitro: Potential alternatives/adjuncts to traditional chelators.

The protective efficacies of N-acetylcysteine (NAC) and N-acetylcysteine amide (NACA) against the toxicity of compounds containing arsenic, cadmium, cobalt, chromium and mercury, were compared to those of dimercaprol, dimercaptosuccinic acid, 2,3-dimercaptopropanesulphonate, D-penicillamine, and derivatives of ethylenediamine tetraacetic acid and diethylenetriaminepentaacetic in CHO-K1 cells. Both NAC and NACA were found to confer protection against these metals, with comparable or better efficacy than many of the test chelators. Results from studies using the glutathione synthesis inhibitor buthionine sulphoximine were consistent with NAC/NACA protection being mediated through both GSH up-regulation and chelation. Given NAC's activity against metal toxicity, widespread clinical use, parenteral or oral routes of administration, high clinical safety, low cost and ease of accessibility, it should be given consideration as a broad-spectrum protectant against toxic metal poisoning as a treatment or adjunct/combination treatment. Its more lipophilic derivative NACA, also warrants attention, especially in those cases where brain toxicity is a concern.