Albano E, Tomasi A, Goria-Gatti L, Iannone A
Dipartimento di Medicina ed Oncologia Sperimentale, Università di Torino, Italy.
Free Radic Biol Med. 1989;6(1):3-8. doi: 10.1016/0891-5849(89)90152-4.
Isolated hepatocytes and liver microsomes incubated with monomethyl-1,1 dimethyl- and 1,2 dimethyl-hydrazines produced free radical intermediates which were detected by ESR spectroscopy by using 4-pyridyl-1-oxide-t-butyl nitrone (4-POBN) as spin trapping agent. The spectral features of the spin adducts derived from all three hydrazine derivatives corresponded to the values reported for the methyl free radical adduct of 4-POBN. In the microsomal preparations inhibitors of the mixed function oxidase system and the destruction of cytochrome P450 by pretreating the rats with CoCl2 all decreased the free radical formation. Methimazole, an inhibitor of FAD-containing monoxygenase system, similarly decreased the activation of 1,1 dimethyl-hydrazine, but not that of monomethyl- and 1,2 dimethyl-hydrazines. The addition to liver microsomes of physiological concentrations of glutathione (GSH) lowered by approx. 80% the intensities of the ESR signals. Consistently, incubation of isolated hepatocytes with methyl-hydrazines decreased the intracellular GSH content, suggesting that GSH can effectively scavenge the methyl free radicals. The results obtained suggest that methyl free radicals could be the alkylating species responsible for the toxic and/or carcinogenic effect of methyl-hydrazines.
将分离的肝细胞和肝微粒体与单甲基肼、1,1 - 二甲基肼和1,2 - 二甲基肼一起孵育，产生了自由基中间体，这些中间体通过电子自旋共振光谱法（ESR）检测，使用4 - 吡啶基 - 1 - 氧化物 - 叔丁基硝酮（4 - POBN）作为自旋捕获剂。源自所有三种肼衍生物的自旋加合物的光谱特征与报道的4 - POBN甲基自由基加合物的值一致。在微粒体制剂中，混合功能氧化酶系统的抑制剂以及通过用CoCl₂预处理大鼠破坏细胞色素P450均降低了自由基的形成。甲巯咪唑，一种含黄素单加氧酶系统的抑制剂，同样降低了1,1 - 二甲基肼的活化，但不降低单甲基肼和1,2 - 二甲基肼的活化。向肝微粒体中添加生理浓度的谷胱甘肽（GSH）使ESR信号强度降低了约80%。一致地，将分离的肝细胞与甲基肼一起孵育会降低细胞内GSH含量，表明GSH可以有效清除甲基自由基。所得结果表明，甲基自由基可能是导致甲基肼毒性和/或致癌作用的烷基化物质。
