CIGMH, Department of Genetics, Faculty of Medical Sciences, Universidade Nova de Lisboa, R. da Junqueira 100, P 1349-008 Lisboa, Portugal.
Institute of Cancer Research, Brookes Lawley Building, Cotswold Road, Sutton SM2 5NG, UK.
Mutat Res. 2012 Aug 30;747(1):86-92. doi: 10.1016/j.mrgentox.2012.04.009. Epub 2012 May 3.
We evaluated the genotoxicity of the food-flavouring agent estragole in V79 cells using the sister chromatid exchange (SCE) assay and the alkaline comet assay. Unexpectedly, we observed an increase in SCE without an exogenous biotransformation system (S9) and a decrease in its presence. Positive results were also observed in the alkaline comet assay without S9, indicating DNA strand breakage. To ascertain repair of damage, we performed the comet assay in V79 cells after two hours of recovery, and observed a reduction of the genotoxic response. Estragole did not produce strand breaks in plasmid DNA in vitro. We then evaluated the formation of DNA adducts in V79 cells by use of the (32)P-postlabelling assay and detected a dose-dependent formation of DNA adducts, which may be responsible for its genotoxicity. We then assayed estragole in the comet assay with two CHO cell lines, a parental AA8 cell line, and an XRCC1-deficient cell line, EM9. Results confirmed the genotoxicity of estragole without biotransformation in both cell lines, although the genotoxicity in EM9 cells compared with that in AA8 cells was not significantly different, suggesting that the XRCC1 protein is not involved in the repair of estragole-induced lesions. Estragole induces apoptosis, but only with high doses (2000μM), and after long treatment periods (24h). Overall, our results suggest that estragole, besides being metabolized to genotoxic metabolites, is a weak direct-acting genotoxin that forms DNA adducts.
我们使用姐妹染色单体交换（SCE）试验和碱性彗星试验评估了调味剂 Estragole 的遗传毒性。出乎意料的是，我们观察到在没有外源性生物转化系统（S9）的情况下 SCE 增加，而在存在 S9 的情况下 SCE 减少。在没有 S9 的碱性彗星试验中也观察到了阳性结果，表明 DNA 链断裂。为了确定损伤的修复，我们在 V79 细胞恢复两小时后进行彗星试验，观察到遗传毒性反应的降低。Estragole 不会在体外质粒 DNA 中产生链断裂。然后，我们使用（32）P-后标记试验评估了 V79 细胞中 DNA 加合物的形成，并检测到 DNA 加合物的剂量依赖性形成，这可能是其遗传毒性的原因。然后，我们在彗星试验中用两种 CHO 细胞系，即亲本 AA8 细胞系和 XRCC1 缺陷细胞系 EM9 检测了 Estragole。结果证实了 Estragole 在没有生物转化的情况下在两种细胞系中均具有遗传毒性，尽管 EM9 细胞中的遗传毒性与 AA8 细胞中的遗传毒性没有显著差异，这表明 XRCC1 蛋白不参与 Estragole 诱导损伤的修复。Estragole 诱导细胞凋亡，但仅在高剂量（2000μM）和长时间处理（24 小时）后才会发生。总的来说，我们的结果表明，Estragole 除了被代谢为遗传毒性代谢物外，还是一种较弱的直接作用遗传毒物，可形成 DNA 加合物。
