Microbiological and Chemical Exposure Assessment Research Division, National Exposure Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, OH 45268, United States.
Chem Res Toxicol. 2011 Apr 18;24(4):475-7. doi: 10.1021/tx200040w. Epub 2011 Mar 9.
The conventional scheme for arsenic methylation accounts for methylated oxyarsenical production but not for thioarsenical formation. Here, we report that in vitro anaerobic microbiota of mouse cecum converts arsenate into oxy- and thio- arsenicals. Besides methylarsonic acid (MMA(V)), arsenate was transformed into six unique metabolites: mono-, di-, and trithio-arsenic acid, monomethyldithio- and monomethyltrithio-arsonic acid, and dimethyldithioarsonic acid. Thioarsenicals were found in soluble and particulate fractions of reaction mixtures, suggesting interactions with anaerobic microbiota. Metabolism of ingested arsenate to oxy- and thio-arsenicals before absorption across the gastrointestinal barrier could affect bioavailability, systemic distribution, and resulting toxicity.
传统的砷甲基化方案可以解释甲基氧砷酸的生成，但不能解释硫代砷酸的形成。在这里，我们报告说，来自小鼠盲肠的体外厌氧微生物群落可将砷酸盐转化为氧代和硫代砷酸。除了甲基砷酸（MMA(V)）外，砷酸盐还转化为六种独特的代谢物：单、二和三硫代砷酸，单甲基二硫代和单甲基三硫代砷酸，以及二甲基二硫代砷酸。硫代砷酸存在于反应混合物的可溶和颗粒部分中，这表明与厌氧微生物群落相互作用。在通过胃肠道屏障吸收之前，将摄入的砷酸盐代谢为氧代和硫代砷酸，可能会影响生物利用度、系统分布和由此产生的毒性。
