代谢
两只因喂食处理过的饲料而每日连续三天服用(嘧啶-2-(14)C)nicosulfuron,sp. act.,62.2 uCi/mg,放射化学纯度>95%,同位素纯度97%,和(吡啶-2-(14)C)nicosulfuron,sp. act.,62.9 uCi/mg,放射化学纯度>95%,同位素纯度>99%的#1号43公斤和#2号34公斤雌性山羊(分别为1.4和1.8毫克/公斤体重)。服用胶囊是用(14)C标记物、13C富集异构体(每个相应环的C2位置)和非放射性nicosulfuron制备的。在服用前,通过LSC对总(14)C活性和通过HPLC进行化学分析对这些胶囊进行了分析。这些胶囊被嵌入一个含有6克山羊饲料的大明胶胶囊中。#1号山羊在适应期住了9天,而#2号山羊则住了11天。两只山羊在服用前后及服用期间均表现出良好的健康和产奶情况。剂量代表基于平均饲料和干草消耗量为1公斤/天的日喂食水平约60 ppm。每天收集牛奶、胆汁、尿液和粪便样本,并通过燃烧/液态闪烁计数进行分析。研究中未使用对照山羊。在服用前至少一天收集牛奶、胆汁、尿液和粪便作为对照样本。...在山羊中nicosulfuron的拟定代谢途径主要显示三种机制:1).sulfonylurea桥的水解产生吡啶磺酰胺和嘧啶胺(两者都会发生进一步的代谢);2)N-脱甲基化随后失去二氧化硫导致环化化合物N2的形成;3)嘧啶环5位的氧化和结合。
Two female goats weighing 43 kg (#1) and 34 kg (#2) (1.4 and 1.8 mg/kg bodyweight respectively), were dosed daily for 3 consecutive days in feed rations treated with (pyrimidine2-(14)C)nicosulfuron, sp. act., 62.2 uCi/mg, radiochemical purity, >95%, isotopic purity, 97%, and (pyridine-2-(14)C)nicosulfuron, sp. act., 62.9 uCi/mg, radiochemical purity, >95%, isotopic purity, >99%, respectively. Dosing capsules were prepared with the (14)C-labeled materials, 13C-enriched isomers (C2 position of each respective ring), and nonradioactive nicosulfuron. The capsules were analyzed prior to dosing by LSC for total (14)C-activity and by HPLC for chemical analysis. These capsules were imbedded in a larger gelatin capsule containing 6 g of goat chow. Goat #1 was housed for a 9-day acclimation period, while goat #2 was kept for 11 days. Both goats showed good health and milk production before and during dosing. The dosage represents a daily feeding level of approximately 60 ppm based on the average feed and hay consumption of 1 kg/day. Samples of milk, bile, urine, and feces were collected daily and analyzed by combustion/liquid scintillation counting. A control goat was not used in the study. Milk, bile, urine, and feces were collected at least one day prior to dosing for use as control samples. ... The proposed metabolic pathway for nicosulfuron in the goat showed primarily three mechanisms: 1) hydrolysis of the sulfonylurea bridge to yield pyridine sulfonamide and pyrimidine amine (both of which undergo additional metabolism); 2) N-demethylation and subsequent loss of sulfur dioxide leading to the cyclized compound N2; and 3) oxidation and conjugation at the 5-position of the pyrimidine ring.
来源:Hazardous Substances Data Bank (HSDB)