LETHAL HYDROXYL RADICAL PRODUCTION IN PARAQUAT-TREATED PLANTS
LETHAL HYDROXYL RADICAL PRODUCTION IN PARAQUAT-TREATED PLANTS
复制标题
DOI：
10.1104/pp.90.4.1267
复制
发表时间：
1989-08-01
期刊：
影响因子：
7.4
通讯作者：
COOLBAUGH, RC
中科院分区：
文献类型：
--
作者：
BABBS, CF;PHAM, JA;COOLBAUGH, RC
联吡啶类除草剂，包括百草枯和diquat，被认为是通过在处理过的植物暴露在阳光下时在叶绿体中产生高活性的氧中心自由基来起作用的。这个假设还没有被特定自由基的直接化学测量所证实。研究人员利用二甲亚砜（DMSO）作为分子探针，对百草枯处理植物的高活性和有害羟基自由基（HO*）的形成进行了检测和量化。DMSO被HO*氧化生成稳定的非自由基化合物甲烷亚磺酸，该化合物可以很容易地从植物组织中提取并用分光光度法测定。最初的实验显示，暴露在阳光下、经过百草枯+二甲二甲砜处理的植物形成了数量惊人的羟基自由基，至少相当于每克新鲜组织在10,000拉德的伽马辐射下产生的HO*自由基的累积数量。这似乎是迄今为止在生物系统中观察到的最大的羟基自由基产生，这足以解释百草枯处理过的植物的顶端生长迅速死亡。
Bipyridinium herbicides, including paraquat and diquat, are believed to act by generating highly reactive, oxygen-centered free radicals within chloroplasts when treated plants are exposed to sunlight. This hypothesis has not yet been confirmed by direct chemical measurements of specific free radicals. We studied paraquat-treated plants using a new method able to detect and quantify formation of highly reactive and deleterius hydroxyl radicals (HO*), in which dimethyl sulfoxide (DMSO) is used as a molecular probe. DMSO is oxidized by HO* to form the stable, nonradical compound, methane sulfinic acid, which can be easily extracted from plant tissue and measured spectrophotometrically. Initial experiments revealed formation of extraordinary numbers of hydroxyl radicals in light-exposed, paraquat + DMSO-treated plants, equivalent at least to the cumulative number of HO* radicals per gram of fresh tissue that would be produced by 10,000 rads of gamma irradiation. This appears to be the greatest production of hydroxyl radicals yet observed in a biological system and is quite sufficient to explain the rapid death of top growth in paraquat-treated plants.