Miguel Fernanda, Augusto Amanda C, Gurgueira Sonia A
San Francisco University, Bragança Paulista, SP, Brazil.
Free Radic Res. 2009 Apr;43(4):340-7. doi: 10.1080/10715760902751894. Epub 2009 Feb 11.
H2O2 can freely crosses membranes and in the presence of Fe2+ (or Cu+) it is prone to participate in Fenton reaction. This study evaluated the concentration and time-dependent effects of H2O2-induced oxidative stress on MnSOD, Se:GPx and catalase and on aconitase. Acute and chronic H2O2 treatments were able to induce oxidative stress in HeLa cells as they significantly decreased aconitase activity and also caused a very significant decrease on antioxidant enzyme activities. The inhibition of enzyme activities was time- and concentration-dependent. Chronic treatment with 5 microM H2O2/h after 24 h was able to decrease all enzyme activities almost at the same level as the acute treatment. Acute and chronic treatments on antioxidant enzyme activities were prevented by cell treatment with ascorbic acid or N-acetylcysteine. These results indicate that antioxidant enzymes can also be affected by the same ROS they produce or neutralize if the time of exposure is long enough.
过氧化氢（H2O2）能够自由穿过细胞膜，并且在亚铁离子（Fe2+）（或铜离子（Cu+））存在的情况下，它易于参与芬顿反应。本研究评估了H2O2诱导的氧化应激对锰超氧化物歧化酶（MnSOD）、硒代谷胱甘肽过氧化物酶（Se:GPx）、过氧化氢酶以及乌头酸酶的浓度和时间依赖性影响。急性和慢性H2O2处理能够在HeLa细胞中诱导氧化应激，因为它们显著降低了乌头酸酶的活性，并且还导致抗氧化酶活性非常显著地下降。酶活性的抑制具有时间和浓度依赖性。在24小时后用5微摩尔/小时的H2O2进行慢性处理，几乎能够使所有酶活性降低到与急性处理相同的水平。用抗坏血酸或N-乙酰半胱氨酸处理细胞可防止急性和慢性处理对抗氧化酶活性的影响。这些结果表明，如果暴露时间足够长，抗氧化酶也会受到它们所产生或中和的相同活性氧的影响。
