BIOLOGY OF PARAQUAT, FREE RADICALS & TRACE METALS

百草枯的生物学，自由基

• 批准号: 3252351
• 负责人: MORDECHAI CHEVION
• 金额: $ 25.95万
• 依托单位: OKLAHOMA MEDICAL RESEARCH FOUNDATION
• 依托单位国家: 美国
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-05-01 至 1990-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3252351
• 关键词: DNA repair; Escherichia coli; biological models; chromosome aberrations; copper; cytolysis; electron microscopy; electron probe spectrometry; electron spin resonance spectroscopy; environmental contamination; environmental toxicology; free radicals; high performance liquid chromatography; hydroquinones; hydroxyl group; iron; oxidation reduction reaction; paraquat; pesticide biological effect; salicylate; superoxides; trace elements

This proposal is focused on the mechanism of the tissue injury caused by exposure to the herbicide, paraquat. Because of its inherent chemical stability, paraquat may pose a serious problem in the environment, as a consequence of its accumulation in soil and crops. Subsequently, it may enter into the water supply and food chain and eventually into the human body. Paraquat in vivo undergoes an enzyme-catalyzed cyclic one-electron reduction and reoxidation which results in the formation of superoxide radicals. Tissue injury caused by paraquat is believed to be associated with molecular oxygen production. The molecular oxygen-induced tissue injury had been often observed to be greatly enhanced by traces of transition metals. An obligatory role for traces of Cu and Fe in the mediation of tissue injury caused by paraquat has been recently demonstrated in a bacterial model and in mice. The experiments proposed in this application are designed to a) determine the degree of correlation between the dose of paraquat, the cellular level of transition metals, and the observed intensity of in vivo production of free radicals, and b) determine the degree of correlation between the dose of paraquat, the cellular level of transition metals, and the observed severity of injury to the organism. An evaluation of the results of studies described in a) and b) should provide insights into the relationship between the level of in vivo free radical production and the degree of biological damage. The dose of paraquat will be varied and the cellular level of transition metals will be manipulated in order to determine how these parameter affect both free radical production and cellular injury. Two biological models will be used: E. coli and mice. In studying each model we will employ three recently developed methods for monitoring the in vivo production of free radicals: 1) HPLC combined with electrochemical detection (HPLC-ECD) of 8-OH-2-deoxyguanosine in DNA, as a measure of .OH attack on chromosomes and subsequent damage to DNA structure, 2) HPLC-EDC analyses of the conversion of salicylate into dihydroxybenzoate as a reporter of the production of .OH radicals in the cytoplasm of cells, and 3) electron paramagnetic resonance (EPR) determination of spin adducts formed from a variety of oxygen- and carbon-centered free radicals as a measure of free radical production in cell membranes. This proposal offers a unique approach for critical evaluation of the role of free radicals in tissue injury in vivo.

该建议的重点是组织损伤的机制， 接触除草剂百草枯。由于其固有的化学性质 稳定性，百草枯可能会对环境造成严重问题， 其在土壤和作物中的积累。随后，它可能 进入水供应和食物链，并最终进入人类 身体 百草枯在体内经历酶催化的环状单电子 还原和再氧化，导致形成超氧化物 根的 百草枯引起的组织损伤被认为与 分子氧的产生。 分子氧诱导的组织 经常观察到， 过渡金属微量的Cu和Fe在植物生长过程中的必然作用 最近， 在细菌模型和小鼠中得到证实。 实验中提出的 该应用被设计为a）确定相关度 百草枯剂量、过渡金属的细胞水平， 观察到的体内自由基产生的强度，和B） 确定百草枯剂量、 过渡金属的细胞水平，以及观察到的损伤严重程度， 有机体 对a）和b）中所述研究结果的评价 B）应提供有关信息水平与 体内自由基的产生和生物损伤的程度。 剂量 百草枯的浓度将有所不同，过渡金属的细胞水平将 为了确定这些参数如何影响自由 自由基产生和细胞损伤。 两个生物模型将被 所用材料：E.大肠杆菌和小鼠。 在研究每个模型时，我们将使用三个 最近开发的用于监测体内游离 自由基：1）HPLC结合电化学检测（HPLC-ECD）， DNA中的8-OH-2-脱氧鸟苷，作为.OH攻击染色体的量度， 随后对DNA结构的损伤，2）转化的HPLC-EDC分析 水杨酸转化为二羟基苯甲酸酯作为.OH产生的报告物 自由基在细胞质中，和3）电子顺磁共振 (EPR)测定各种氧-和 以碳为中心的自由基作为自由基产生的衡量标准， 细胞膜 该提案为关键问题提供了一种独特的方法 评价自由基在体内组织损伤中的作用。