Quinclorac ester toxicity and metabolism in leafy spurge (Euphorbia esula) soil systems:: Effects of foliar vs soil applications'
Quinclorac ester toxicity and metabolism in leafy spurge (Euphorbia esula) soil systems:: Effects of foliar vs soil applications'
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DOI：
10.1006/pest.1998.2357
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发表时间：
1998-09-01
影响因子：
4.7
通讯作者：
Lamoureux, GL
中科院分区：
文献类型：
--
作者：
Rusness, DG;Huwe, JK;Lamoureux, GL
二氯喹啉酸和13种合成酯在叶面和土壤处理的多叶大戟植物中的毒性进行了监测。用二氯喹啉酸以0.5 μ mol/株进行叶面处理导致100%死亡率，而用酯以2 μ mol/株进行处理显示初始毒性症状，但植物随时间（24周）恢复。叶片毒性症状和死亡率增加，在整个24周后，土壤处理在0.4 μ mol/株高分子量酯（C5-C16），然而，毒性症状减少，植物恢复后，二氯喹啉酸或低分子量酯处理。还对[C-14]二氯喹啉酸酯类进行了监测，以确定毒性数据是否与酯类迁移率和/或代谢有关。叶面施用表现出挥发性损失与低分子量酯;酯的完全代谢发生在处理的叶内的7天，但很少或没有观察到二氯喹啉酸的结果;和很少的放射性标记迁移的叶子。土壤应用表明，酯代谢的土壤微生物通过一系列的ω-和P-氧化，而不是简单的酯水解。通过MS和NMR分析鉴定了这些中间代谢物。C6和C8酯在转化为二氯喹啉酸之前在土壤中代谢为4-羟基丁酸的二氯喹啉酸酯作为主要中间体。从各种酯中释放二氯喹啉酸的罕见性取决于酯侧链中奇数碳与偶数碳的数量; C7、C5和C8酯分别以16、3.2和1的相对速率代谢为二氯喹啉酸。土壤中的二氯喹啉酸易被水淋溶，而C8酯则被吸附。随着时间的推移，较高MW的酯在土壤中释放二氯喹啉酸，同时，用这些酯处理后的叶大戟的毒性也增加，并且在24周后上级优于二氯喹啉酸。从这些酯的ω/β-氧化中缓慢释放二氯喹啉酸似乎增加了在土壤处理的多叶大戟中的功效。
Quinclorac and 13 synthesized esters were monitored for toxicity in foliar- and soil-treated leafy spurge plants. Foliar treatment at 0.5 mu mol/plant with quinclorac resulted with 100% mortality, whereas treatment with esters at 2 mu mol/plant showed initial toxicity symptoms, but the plants recovered with time (24 weeks). Foliar toxicity symptoms and mortality increased throughout 24 weeks after soil treatment at 0.4 mu mol/plant with the higher MW esters (C5-C16); however, toxicity symptoms decreased and plants recovered after quinclorac or low MW ester treatments. [C-14]Quinclorac esters also were monitored to ascertain if toxicity data could be related to ester mobility and/or metabolism. Foliar application showed volatile losses with the low MW esters; complete metabolism of esters occurred inside the treated leaves by 7 days, but little or no quinclorac was observed as a result; and little radiolabel migrated from the leaves. Soil application showed that the esters were metabolized by soil microorganisms through a series of omega- and P-oxidations and not by simple ester hydrolysis. These intermediate metabolites were identified by MS and NMR analyses. The C6 and C8 esters were metabolized to the quinclorac ester of 4-hydroxybutryic acid as a major intermediate in soil before conversion to quinclorac. The rare of quinclorac release from the various esters was dependent on the number of odd vs even carbons in the ester side chain; the C7, C5, and C8 esters were metabolized to quinclorac at relative rates of 16, 3.2, and 1, respectively. Quinclorac acid was leached readily from soil with water, but the C8 ester was adsorbed. As the higher MW esters released quinclorac in soil over time, concomitantly, the toxicity of leafy spurge after treatment with these esters also increased and was superior to quinclorac after 24 weeks. The slow release of quinclorac from the omega/beta-oxidations of these esters appeared to increase efficacy in soil-treated leafy spurge.