Zhao Yuling, Gao Zhonghong, Li Hailing, Xu Huibi
Department of Chemistry, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, PR China.
Biochim Biophys Acta. 2004 Nov 18;1675(1-3):105-12. doi: 10.1016/j.bbagen.2004.08.011.
Oxidative injury has been implicated in the pathogenesis of numerous neurodegenerative diseases. Recently, it has been found that with the existence of hydrogen peroxide and nitrite, hemin catalyzes protein nitration. We hypothesize under certain pathological conditions, hemin catalyzed protein nitration may happen in the brain. In this paper, the effects of three flavonoids, i.e. quercetin, catachin and baicalein on hemin/nitrite/H2O2 induced brain homogenate oxidation and nitration were studied. The results showed that hemin/nitrite/H2O2 system could effectively induce brain homogenate protein oxidation and nitration. Quercetin, catachin and baicalein dose-dependently inhibited hemin/nitrite/H2O2 system-induced protein nitration in a dose-dependent manner, the inhibition of protein nitration was in the order of quercetin>catachin>baicalein. These compounds also inhibited hemin/H2O2 system-induced lipid peroxidation, the inhibition order was baicalein >quercetin>catachin. However, these flavonoids showed marginal effect on hemin/nitrite/H2O2 system caused protein oxidation and thiol oxidation. The inhibition activities of flavonoids on hemin/nitrite/H2O2 system-induced protein nitration may closely relate to their radical scavenging activities, since the inhibition order of protein nitration is the same as the radical scavenging order. These results indicate hemin/nitrite/H2O2 system induces different types of oxidative assault on bio-molecules. Flavonoids could act as antioxidants inhibiting ROS and RNS caused brain damage.
氧化损伤与多种神经退行性疾病的发病机制有关。最近，人们发现，在过氧化氢和亚硝酸盐存在的情况下，血红素会催化蛋白质硝化反应。我们推测，在某些病理条件下，血红素催化的蛋白质硝化反应可能会在大脑中发生。本文研究了三种黄酮类化合物，即槲皮素、儿茶素和黄芩苷对血红素/亚硝酸盐/H2O2诱导的脑匀浆氧化和硝化反应的影响。结果表明，血红素/亚硝酸盐/H2O2体系能有效诱导脑匀浆蛋白质氧化和硝化反应。槲皮素、儿茶素和黄芩苷均呈剂量依赖性抑制血红素/亚硝酸盐/H2O2体系诱导的蛋白质硝化反应，对蛋白质硝化反应的抑制作用顺序为槲皮素>儿茶素>黄芩苷。这些化合物还抑制了血红素/H2O2体系诱导的脂质过氧化反应，抑制作用顺序为黄芩苷>槲皮素>儿茶素。然而，这些黄酮类化合物对血红素/亚硝酸盐/H2O2体系引起的蛋白质氧化和硫醇氧化作用甚微。黄酮类化合物对血红素/亚硝酸盐/H2O2体系诱导的蛋白质硝化反应的抑制活性可能与其自由基清除活性密切相关，因为蛋白质硝化反应的抑制顺序与自由基清除顺序相同。这些结果表明，血红素/亚硝酸盐/H2O2体系会对生物分子引发不同类型的氧化攻击。黄酮类化合物可作为抗氧化剂，抑制活性氧和活性氮对大脑造成的损伤。
