Kashima M
Department of Endodontics, Nihon University School of Dentistry at Matsudo, Chiba, Japan.
Chem Pharm Bull (Tokyo). 1999 Feb;47(2):279-83. doi: 10.1248/cpb.47.279.
Superoxide (O2-.) was reduced by the addition of superoxide dismutase (SOD: O2-. scavenger) and catechins. In competitive reactions utilizing different concentrations of spin-trap agent, the IC50 values of each sample were changed. With regard to the Cu2+/H2O2 and Fe2+/H2O2 reaction systems, metal chelater, hydroxyl radical (.OH) scavenger and catechins eliminated the levels of .OH. For the Cu2+/H2O2 reaction systems, the IC50 for .OH scavenger changed, but that for metal chelater and catechins did not. However, for the Fe2+/H2O2 reaction system, the IC50 for .OH scavenger and catechins changed, whereas that for metal chelater did not. The ESR signal for free Cu2+ was changed by addition of metal chelater and catechins. In the spectrophotometer experiments, it was confirmed that the CuCl2 spectrum was changed by addition of metal chelater and catechins but not by .OH scavenger. Conversely, the FeSO4 spectrum was not changed by addition of .OH scavenger or catechins, but was altered by metal chelater. Lipid peroxidation was inhibited by catechins in a concentration-dependent manner. Therefore, it was suggested that the catechins did not scavenge directly the generated .OH from the Cu2+/H2O2 reaction system, but inhibited the generation of .OH by acting on the Cu2+/H2O2 reaction system. On the other hand, with respect to the .OH generated from the Fe2+/H2O2 reaction system, it was suggested that the catechins had a direct scavenging capacity of the .OH, but had little chelating activity of iron. It was confirmed that catechins have the ability to scavenge for O2-. as well as .OH and to inhibit the generation of .OH by chelation with metal ions.
通过添加超氧化物歧化酶（SOD：超氧阴离子清除剂）和儿茶素可使超氧阴离子（O2-.）减少。在使用不同浓度自旋捕获剂的竞争性反应中，每个样品的半数抑制浓度（IC50）值发生了变化。对于Cu2+/H2O2和Fe2+/H2O2反应体系，金属螯合剂、羟基自由基（.OH）清除剂和儿茶素可消除.OH的水平。对于Cu2+/H2O2反应体系，.OH清除剂的IC50发生了变化，但金属螯合剂和儿茶素的IC50未变。然而，对于Fe2+/H2O2反应体系，.OH清除剂和儿茶素的IC50发生了变化，而金属螯合剂的IC50未变。添加金属螯合剂和儿茶素可改变游离Cu2+的电子自旋共振（ESR）信号。在分光光度计实验中，证实添加金属螯合剂和儿茶素可改变CuCl2光谱，但.OH清除剂不会。相反，添加.OH清除剂或儿茶素不会改变FeSO4光谱，但金属螯合剂会改变其光谱。儿茶素以浓度依赖的方式抑制脂质过氧化。因此，提示儿茶素不会直接清除Cu2+/H2O2反应体系中产生的.OH，而是通过作用于Cu2+/H2O2反应体系来抑制.OH的产生。另一方面，对于Fe2+/H2O2反应体系产生的.OH，提示儿茶素具有直接清除.OH的能力，但对铁的螯合活性很小。证实儿茶素具有清除O2-.以及.OH的能力，并可通过与金属离子螯合来抑制.OH的产生。
