Introduction

Pyrrolizidine alkaloids (PAs) are found in many plant species as secondary metabolites which affect humans via contaminated food sources, herbal medicines and dietary supplements. Hundreds of compounds belonging to PAs have been identified. PAs undergo hepatic metabolism, after which they can induce hepatotoxicity and carcinogenicity. Many aspects of their mechanism of carcinogenicity are still unclear and it is important for human risk assessment to investigate this class of compounds further.

Material and methods

Human hepatoma cells HepG2 were used to investigate the genotoxicity of different chemical structural classes of PAs, namely europine, lycopsamine, retrorsine, riddelliine, seneciphylline, echimidine and lasiocarpine, in the cytokinesis-block micronucleus (CBMN) assay. The different ester type PAs europine, seneciphylline, and lasiocarpine were also tested in human hepatoma Huh6 cells. Six different PAs were investigated in a crosslink comet assay in HepG2 cells.

Results

The maximal increase of micronucleus formation was for all PAs in the range of 1.64–2.0 fold. The lowest concentrations at which significant induction of micronuclei were found were 3.2 μM for lasiocarpine and riddelliine, 32 μM for retrorsine and echimidine, and 100 μM for seneciphylline, europine and lycopsamine. Significant induction of micronuclei by lasiocarpine, seneciphylline, and europine were achieved in Huh6 cells at similar concentrations. Reduced tail formation after hydrogen peroxide treatment was found in the crosslink comet assay for all diester type PAs, while an equimolar concentration of the monoesters europine and lycopsamine did not significantly reduce DNA migration.

Conclusion

The widely available human hepatoma cell lines HepG2 and Huh6 were suitable for the assessment of PA-induced genotoxicity. Selected PAs confirmed previously published potency rankings in the micronucleus assay. In HepG2 cells, the crosslinking activity was related to the ester type, which is a first report of PA mediated effects in the comet assay.

中文翻译：

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选定的吡咯里西啶生物碱在人肝癌细胞系 HepG2 和 Huh6 中的遗传毒性

介绍

吡咯里西啶生物碱 (PA) 作为次生代谢物存在于许多植物物种中，它们通过受污染的食物来源、草药和膳食补充剂影响人类。已经鉴定了数百种属于 PA 的化合物。PAs 经历肝脏代谢，之后它们可以诱导肝毒性和致癌性。其致癌机制的许多方面仍不清楚，进一步研究此类化合物对于人类风险评估很重要。

材料与方法

在胞质分裂阻断微核 (CBMN) 试验中，人类肝癌细胞 HepG2 用于研究不同化学结构类别的 PAs，即欧品碱、番茄红素、逆转录酶、瑞德林碱、seneciphylline、echimidine 和 lasiocarpine 的遗传毒性。还在人肝癌 Huh6 细胞中测试了不同的酯类 PAs 欧品碱、seneciphylline 和 lasiocarpine。在 HepG2 细胞中的交联彗星试验中研究了六种不同的 PA。

结果

对于所有 PA，微核形成的最大增加范围为 1.64-2.0 倍。发现显着诱导微核的最低浓度是 lasiocarpine 和riddelliine 的 3.2 μM，逆曲辛和 echimidine 的 32 μM，以及 seneciphylline、europine 和 lycopsamine 的 100 μM。在类似浓度的 Huh6 细胞中，海果碱、千叶茶碱和欧品碱显着诱导微核。在所有二酯型 PA 的交联彗星试验中发现过氧化氢处理后尾部形成减少，而等摩尔浓度的单酯欧洲碱和番茄红素并未显着减少 DNA 迁移。

结论

广泛可用的人肝癌细胞系 HepG2 和 Huh6 适用于评估 PA 诱导的基因毒性。选定的 PA 证实了先前公布的微核试验中的效力排名。在 HepG2 细胞中，交联活性与酯类型有关，这是彗星试验中 PA 介导效应的首次报道。