Ultimate carcinogenetic compound of arsenic : the chemical structure and the toxicity

我们之前的研究发现，长期口服二甲基larsinic acid （DMAV）的大鼠在尿液和粪便中检测到不明代谢物M1、M2和M3。此外，我们报道了大肠杆菌A3-6将DMAV转化为M-2和M-3，并将氧化三甲基larsin （TMAO）转化为M1，大肠杆菌A3-6将DMAV转化为M2和M-3需要半胱氨酸（Cys）。在这项研究中，我们在体外和体内研究了这些未知代谢物的产生机制。在体外实验中，DMAV在Cys和A3-6存在的情况下转化为M2，并进一步转化为M3。TMAO迅速转化为M1。M2浓度在Cys/DMA比为2时达到最大值，M3浓度在Cys/DMA比大于3时达到最大值。体内试验结果表明，饲料中添加Cys和大肠杆菌影响了M2和M3的产量。此外，我们还通过LC- icp -MS和LC/MS检测了M-2的化学性质。M2被过氧化氢氧化为DMAV，表明M2可能是DMA复合物。M2与代谢亚硫酸盐-硫代硫酸盐试剂的DMAV反应物一致。M-2分子量为154，是一种含硫代谢物。研究了未识别代谢物的细胞毒性。M2对V79细胞的细胞毒性大于DMAV、M1和M3。加入超氧化物歧化酶后，M2在HL-60细胞中的细胞毒性降低，提示M2的细胞毒性可能与活性氧的产生有关。

Our previous study revealed that unidentified metabolites, M1, M2, and M3, were detected in urine and feces after long-term oral administration of dimethylarsinic acid (DMAV) to rats. In addition, we reported that the E.coli A3-6 converted DMAV to M-2 and M-3 and converted Trimethylarsine oxide (TMAO) to M1, and the conversion of DMAV to M2 and M-3 by E.coli A3-6 required cysteine (Cys). In this study we examined the mechanism of production of these unknown metabolites in vitro and in vivo. In vitro study, DMAV was converted to M2 and further to M3 in the presence of Cys and A3-6. TMAO was rapidly converted to M1. The maximum concentration of M2 was observed at a Cys/DMA ratio of 2, and the maximum of M3 was observed when the ratio exceeded 3. In vivo experiment, the results indicated that dietary Cys and E.coli affected the production of M2 and M3. In addition, we examined the chemical properties of M-2 by LC-ICP-MS and LC/MS. M2 was oxidized to DMAV by hydrogen peroxide, suggesting that M2 may be a DMA complex. M2 was consistent with the reactant of DMAV with metabisulfite-thiosulfate reagent. The molecular weight of M-2 was 154 and M-2 was a sulfur-containing metabolite.The cytotoxicity of the unidentified metabolites was investigated. M2 was more cytotoxic than DMAV, M1, and M3 in V79 cells. Cytotoxicity of M2 in HL-60 cells was decreased by the addition of superoxide dismutase, suggesting that the cytotoxicity of M2 might be due to the production of reactive oxygen species.