Fuke C, Ameno K, Ameno S, Kiriu T, Shinohara T, Ijiri I
Department of Forensic Medicine, Kagawa Medical School, Japan.
Nihon Hoigaku Zasshi. 1993 Feb;47(1):33-45.
The metabolism of paraquat and diquat was studied in vitro using rat liver homogenates, and the resulting metabolites were identified. Rat liver was homogenized with three volumes of isotonic buffer, and aliquots of the homogenate were preheated in a boiling water bath for 5 min prior to use. One milliliter of a mixture including both paraquat and diquat in an isotonic buffer solution (10 micrograms ion/ml) was incubated with an equal volume of fresh or preheated homogenate for 1 to 60 min at 37 degrees C. Quantification of paraquat and diquat was carried out by high-performance liquid chromatography (HPLC). In the fresh homogenate, a gradual decrease of paraquat concentration (about a 30% decrease over 60 min of incubation) and a rapid decrease of diquat concentration (not detectable after 10 min of incubation) were observed, but the same phenomenon was not evident with the preheated homogenate. Analysis of the incubated mixture of fresh liver homogenate with paraquat and diquat revealed three unknown peaks on the HPLC chromatograms; these seemed to be breakdown products of paraquant and diquat. The products were isolated and purified from the mixture by Sep-Pak C18 cartridge extraction, HPLC, silica gel column chromatography and Sephadex LH-20 column chromatography. Analysis of the chemical structure of the purified compounds was performed by infrared spectroscopy, mass spectrometry and nuclear magnetic resonance spectroscopy. These analyses determined that paraquat-monopyridone (1',2'-dihydro-1,1'-dimethyl-2-oxo-4,4'-bipyridylium ion) was derived from paraquat, and that diquat-monopyridone (6,7-dihydro-4-oxodipyrido [1,2-a':2',1'-c] pyrazinium ion) and diquat-dipyridone (6,7-dihydrodipyrido [1,2-a:2',1'-c] pyrazine-4,9-dione) were derived from diquat. These results indicate that paraquat and diquat are metabolized by rat liver homogenate, diquat more readily so than paraquat. As the toxicity of these metabolites has been reported to be much lower than those of the parental compounds, it would seem that there is a system capable of detoxifying paraquat and diquat in rat liver.
利用大鼠肝脏匀浆在体外研究了百草枯和敌草快的代谢过程，并对产生的代谢产物进行了鉴定。将大鼠肝脏与三倍体积的等渗缓冲液匀浆，匀浆的等分试样在使用前于沸水浴中预热5分钟。将1毫升等渗缓冲溶液（10微克离子/毫升）中同时含有百草枯和敌草快的混合物与等体积的新鲜或预热匀浆在37℃下孵育1至60分钟。通过高效液相色谱法（HPLC）对百草枯和敌草快进行定量分析。在新鲜匀浆中，观察到百草枯浓度逐渐降低（孵育60分钟内约降低30%），敌草快浓度迅速降低（孵育10分钟后无法检测到），但预热匀浆中未出现相同现象。对新鲜肝脏匀浆与百草枯和敌草快的孵育混合物进行分析，在HPLC色谱图上发现了三个未知峰；这些似乎是百草枯和敌草快的分解产物。通过Sep-Pak C18柱萃取、HPLC、硅胶柱色谱和Sephadex LH-20柱色谱从混合物中分离并纯化这些产物。通过红外光谱、质谱和核磁共振光谱对纯化化合物的化学结构进行分析。这些分析确定百草枯单吡啶酮（1',2'-二氢-1,1'-二甲基-2-氧代-4,4'-联吡啶鎓离子）源自百草枯，敌草快单吡啶酮（6,7-二氢-4-氧代二吡啶并[1,2-a':2',1'-c]吡嗪鎓离子）和敌草快二吡啶酮（6,7-二氢二吡啶并[1,2-a:2',1'-c]吡嗪-4,9-二酮）源自敌草快。这些结果表明百草枯和敌草快可被大鼠肝脏匀浆代谢，敌草快比百草枯更容易代谢。由于据报道这些代谢产物的毒性远低于母体化合物，似乎大鼠肝脏中存在一个能够使百草枯和敌草快解毒的系统。
