Thionate versus Oxon: Comparison of Stability, Uptake, and Cell Toxicity of ((CH3O)-C-14)(2)-Labeled Methyl Parathion and Methyl Paraoxon with SH-SY5Y Cells

Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, MT 59812, USA.
Journal of Agricultural and Food Chemistry (Impact Factor: 3.11). 07/2010; 58(14):8460-6. DOI: 10.1021/jf100976v
Source: PubMed

ABSTRACT The stability, hydrolysis, and uptake of the organophosphates methyl parathion and methyl paraoxon were investigated in SH-SY5Y cells. The stabilities of ((14)CH(3)O)(2)-methyl parathion ((14)C-MPS) and ((14)CH(3)O)(2)-methyl paraoxon ((14)C-MPO) at 1 microM in culture media had similar half-lives of 91.7 and 101.9 h, respectively. However, 100 microM MPO caused >95% cytotoxicity at 24 h, whereas 100 microM MPS caused 4-5% cytotoxicity at 24 h ( approximately 60% cytotoxicity at 48 h). Greater radioactivity was detected inside cells treated with MPO as compared to MPS, although >80% of the total MPO uptake was primarily dimethyl phosphate (DMP). Maximum uptake was reached after 48 h of (14)C-MPS or (14)C-MPO exposure with total uptakes of 1.19 and 1.76 nM/10(6) cells for MPS and MPO, respectively. The amounts of MPS and MPO detected in the cytosol after 48 h of exposure time were 0.54 and 0.37 nM/10(6) cells, respectively.

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May 16, 2014