Spooren A A, Evelo C T
Department of Pharmacology (toxicology section), University Maastricht, The Netherlands.
Arch Toxicol. 1997;71(5):299-305. doi: 10.1007/s002040050390.
Hydroxylamine (HYAM, HONH2) and some of its derivatives are known to cause erythrotoxic effects both in vitro and in vivo. Previous studies have shown that the primary in vitro effect of HYAM and O-ethyl hydroxylamine (OEH) is methaemoglobin formation, leading to liberation of free radicals which cause lipid peroxidation, enzyme inhibitions and glutathione depletion. By contrast, N-substituted N,O-dimethyl hydroxylamine (NODMH), primarily induces impairment of glucose 6-phosphate dehydrogenase (G6PDH) and glutathione reductase (GR). The oxidative potency of HYAM and the O-derivative was larger than the potency of the N,O-derivative. This seemed to indicate that attachment of an alkyl group to the nitrogen atom of hydroxylamine leads to decreased reactivity. To achieve a better understanding of the structure activity relationship for hydroxylamines three methylated derivatives were tested: N-methyl hydroxylamine (NMH). N-dimethyl hydroxylamine (NDMH) and O-methyl hydroxylamine (OMH). We were also interested in the erythrotoxic potency of OMH which recently entered industrial production. Methaemoglobin formation, high release of lipid peroxidation products, inhibition of NADPH methaemoglobin reductase and glutathione S-transferase (GST) and depletion of total glutathione (GT) were seen for OMH. The reducing enzymes G6PDH and GR were not impaired by OMH. These findings for OMH are consistent with the proposed mechanism for O-derivatives. Since both the effects caused by OMH and its potency are comparable to those of HYAM and OEH this indicates that possible occupational exposure to this compound may be approached similarly to HYAM and OEH. NMH only inhibited G6PDH and GR activity, which is fully in accord with the proposed mechanism for N-substituted derivatives of HYAM. However, NDMH a double N-substituted compound, caused a strikingly different scheme of reactivity inhibition of G6PDH but not of GR, severe methaemoglobin formation, only little lipid peroxidation and some impairment of NADPH methaemoglobin reductase. This study confirms that O-derivatives of HYAM are potent haemoglobin oxidators, leading to other oxidative effects. The main effect was confirmed for single N-derivatives as inhibition of the two protective enzymes G6PDH and GR. However, the results for NDMH indicate that this simple classification of O-derivatives and N-derivatives has to be extended for double N-substituted compounds which give a mixture of effects.
已知羟胺（HYAM，HONH₂）及其一些衍生物在体外和体内均会产生红细胞毒性作用。先前的研究表明，HYAM和O - 乙基羟胺（OEH）在体外的主要作用是形成高铁血红蛋白，导致自由基的释放，进而引起脂质过氧化、酶抑制和谷胱甘肽耗竭。相比之下，N - 取代的N，O - 二甲基羟胺（NODMH）主要诱导葡萄糖6 - 磷酸脱氢酶（G6PDH）和谷胱甘肽还原酶（GR）的损伤。HYAM及其O - 衍生物的氧化能力大于N，O - 衍生物的能力。这似乎表明在羟胺的氮原子上连接烷基会导致反应性降低。为了更好地理解羟胺的构效关系，测试了三种甲基化衍生物：N - 甲基羟胺（NMH）、N，N - 二甲基羟胺（NDMH）和O - 甲基羟胺（OMH）。我们还对最近进入工业生产的OMH的红细胞毒性效力感兴趣。OMH可导致高铁血红蛋白形成、脂质过氧化产物的大量释放、NADPH高铁血红蛋白还原酶和谷胱甘肽S - 转移酶（GST）的抑制以及总谷胱甘肽（GT）的耗竭。还原酶G6PDH和GR未受到OMH的损伤。OMH的这些发现与所提出的O - 衍生物机制一致。由于OMH引起的效应及其效力与HYAM和OEH相当，这表明对该化合物可能的职业暴露的处理方式可类似于HYAM和OEH。NMH仅抑制G6PDH和GR活性，这完全符合所提出的HYAM的N - 取代衍生物机制。然而，NDMH这种双N - 取代化合物，对G6PDH的反应性抑制模式显著不同，但对GR无抑制，会导致严重的高铁血红蛋白形成、仅少量的脂质过氧化以及NADPH高铁血红蛋白还原酶的一些损伤。本研究证实，HYAM的O - 衍生物是有效的血红蛋白氧化剂，会导致其他氧化效应。对于单一N - 衍生物，主要效应被确认为对两种保护酶G6PDH和GR的抑制。然而，NDMH的结果表明，对于产生混合效应的双N - 取代化合物，这种O - 衍生物和N - 衍生物的简单分类必须扩展。
