Skourti-Stathaki Eirini, Clauson-Kaas Frederik, Brandt Kristian Koefoed, Rasmussen Lars Holm, Hansen Hans Christian Bruun
Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C., Denmark.
Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C., Denmark.
Chemosphere. 2016 Dec;165:453-459. doi: 10.1016/j.chemosphere.2016.09.050. Epub 2016 Sep 30.
Bracken ferns (Pteridium spp.) are well-known for their carcinogenic properties, which are ascribed to the content of ptaquiloside and ptaquiloside-like substances. Ptaquiloside leach from the ferns and may cause contamination of drinking water. Pterosin B is formed by hydrolysis of ptaquiloside. In soil, Pterosin B is adsorbed more strongly and it is expected to have a slower turnover than ptaquiloside. We thus hypothesized that pterosin B may serve as an indicator for any past presence of ptaquiloside. Pterosin B degradation was studied in acid forest soils from bracken-covered and bracken-free areas. Soil samples were incubated with pterosin B at 3 and 8 μg g for 10 days, whereas sterile (autoclaved) samples were incubated for 23 days. Pterosin B showed unexpected fast degradation in soils with full degradation in topsoils in 2-5 days. Pterosin B dissipation followed the sum of two-first order reactions. The initial fast reaction with half-lives of 0.7-3.5 h contributed 11-59% of the total pterosin B degradation, while the slow reaction was 20-100 times slower than the fast reaction. Total dissipation half-lives were shorter for loamy sand (4 h) than for sandy loam soils (28 h). No degradation of pterosin B took place under sterile conditions assuming observed dissipation during the first 3 h could be attributed to irreversible sorption. Our results demonstrate that pterosin B is microbially degraded and that pterosin B is as unstable as ptaquiloside and hence cannot be used as an indicator for former presence of ptaquiloside in soil.
蕨菜（蕨属植物）以其致癌特性而闻名，这归因于其ptaquiloside和ptaquiloside类物质的含量。ptaquiloside从蕨菜中浸出，可能会污染饮用水。Pterosin B是由ptaquiloside水解形成的。在土壤中，Pterosin B的吸附更强，预计其周转速度比ptaquiloside慢。因此，我们假设Pterosin B可能作为过去存在ptaquiloside的指标。在蕨菜覆盖和无蕨菜区域的酸性森林土壤中研究了Pterosin B的降解情况。土壤样品与Pterosin B分别以3μg/g和8μg/g的浓度孵育10天，而无菌（高压灭菌）样品孵育23天。Pterosin B在土壤中显示出意想不到的快速降解，表土在2 - 5天内完全降解。Pterosin B的消散遵循两个一级反应的总和。初始快速反应的半衰期为0.7 - 3.5小时，占Pterosin B总降解量的11 - 59%，而慢速反应比快速反应慢20 - 100倍。壤质砂土（4小时）的总消散半衰期比砂壤土（28小时）短。在无菌条件下，Pterosin B没有发生降解，假设在前3小时观察到的消散可归因于不可逆吸附。我们的结果表明，Pterosin B被微生物降解，并且Pterosin B与ptaquiloside一样不稳定，因此不能用作土壤中先前存在ptaquiloside的指标。
