Palmen N G, Evelo C T
Department of Pharmacology and Toxicology, Universiteit Maastricht, The Netherlands.
Arch Toxicol. 1998 Apr;72(5):270-6. doi: 10.1007/s002040050501.
Both oximes and hydroxylamine (HYAM) are compounds with known oxidative capacity. We tested in vitro whether acetaldoxime (AAO), cyclohexanone oxime (CHO), methyl ethyl ketoxime (MEKO) or HYAM affect haemoglobin oxidation (into HbFe3+), formation of thiobarbituric acid reactive substances (TBARS), and glutathione (GT) depletion in human haemolysate, erythrocytes or blood. All these parameters are known to be related to oxidative stress. Glutathione S-transferase (GST) activity was measured as it may be affected by oxygen radicals. All three oximes caused a low degree of HbFe3+ accumulation in erythrocytes. This was higher in haemolysates indicating that membrane transport may be limiting or that protective mechanisms within erythrocytes are more effective. HbFe3+ accumulation was lower for the oximes than for HYAM. AAO and HYAM caused TBARS formation in blood. For HYAM this was expected as free radicals are known to be generated during HbFe3+ formation. Free radical generation by AAO and HYAM in erythrocytes was confirmed by the inhibition of GST. For the other two oximes (CHO and MEKO) some special effects were found. CHO did inhibit erythrocyte GST while it did not cause TBARS formation. MEKO was the least potent oxime as it caused no TBARS formation, little HbFe3+ accumulation and little GST inhibition in erythrocytes. However, GT depletion was more pronounced for MEKO than for the other oximes, indicating that glutathione conjugation occurs. TBARS formation, GT depletion and GST modulation caused by the oximes and HYAM were also tested in rat hepatocytes. However, no effects were found in hepatocytes. This suggests that a factor present in erythrocytes is necessary for free radical formation. Studies with proposed metabolites of the oximes (i.e. cyclohexanone, acetaldehyde or methylethyl ketone) and addition of rat liver preparations to the erythrocyte incubations with oximes, suggest that metabolism is not a limiting factor in erythrocyte toxicity.
肟类化合物和羟胺（HYAM）都是具有已知氧化能力的化合物。我们在体外测试了乙醛肟（AAO）、环己酮肟（CHO）、甲乙酮肟（MEKO）或HYAM是否会影响人溶血产物、红细胞或血液中血红蛋白的氧化（生成高铁血红蛋白HbFe3+）、硫代巴比妥酸反应性物质（TBARS）的形成以及谷胱甘肽（GT）的消耗。所有这些参数都已知与氧化应激有关。由于谷胱甘肽S-转移酶（GST）活性可能会受到氧自由基的影响，因此对其进行了测定。所有三种肟类化合物都会导致红细胞中高铁血红蛋白HbFe3+的积累程度较低。在溶血产物中这种积累程度更高，这表明膜转运可能具有限制作用，或者红细胞内的保护机制更有效。肟类化合物导致的高铁血红蛋白HbFe3+积累低于HYAM。AAO和HYAM会导致血液中TBARS的形成。对于HYAM来说，这是可以预料的，因为已知在高铁血红蛋白HbFe3+形成过程中会产生自由基。通过抑制GST证实了AAO和HYAM在红细胞中会产生自由基。对于另外两种肟类化合物（CHO和MEKO），发现了一些特殊作用。CHO确实会抑制红细胞GST，但不会导致TBARS形成。MEKO是活性最低的肟类化合物，因为它不会导致TBARS形成，红细胞中高铁血红蛋白HbFe3+的积累很少，对GST的抑制作用也很小。然而，MEKO导致的GT消耗比其他肟类化合物更明显，这表明发生了谷胱甘肽结合反应。肟类化合物和HYAM导致的TBARS形成、GT消耗和GST调节也在大鼠肝细胞中进行了测试。然而，在肝细胞中未发现任何影响。这表明红细胞中存在的一种因子对于自由基的形成是必需的。对肟类化合物的假定代谢产物（即环己酮、乙醛或甲乙酮）进行的研究，以及在含有肟类化合物的红细胞孵育体系中添加大鼠肝脏制剂的研究表明，代谢不是红细胞毒性的限制因素。
