Reactive oxygen species are integral to many physiological processes. Although their roles are still being elucidated, they seem to be linked to a variety of disorders and may represent promising drug targets. Mimics of superoxide dismutases, which catalyse the decomposition of O₂^•− to H₂O₂ and O₂, have traditionally used redox-active metals, which are toxic outside of a tightly coordinating ligand. Purely organic antioxidants have also been investigated but generally require stoichiometric, rather than catalytic, doses. Here, we show that a complex of the redox-inactive metal zinc(ii) with a hexadentate ligand containing a redox-active quinol can catalytically degrade superoxide, as demonstrated by both reactivity assays and stopped-flow kinetics studies of direct reactions with O₂^•− and the zinc(ii) complex. The observed superoxide dismutase catalysis has an important advantage over previously reported work in that it is hastened, rather than impeded, by the presence of phosphate, the concentration of which is high under physiological conditions.

活性氧是许多生理过程必不可少的。尽管仍未阐明其作用，但它们似乎与多种疾病有关，可能代表有希望的药物靶标。传统上，超氧化物歧化酶的模拟物催化O ₂ ^•-分解为H ₂ O ₂和O ₂，它们使用的氧化还原活性金属在紧密配位的配体之外是有毒的。也已经研究了纯有机抗氧化剂，但通常需要化学计量剂量，而不是催化剂量。在这里，我们显示了氧化还原惰性金属锌（ii）与含氧化还原活性的奎诺尔的六齿配体可以催化降解超氧化物，如反应性测定和与O ₂ ^{• -}和锌（ii）配合物直接反应的停流动力学研究所证明。与先前报道的工作相比，观察到的超氧化物歧化酶催化具有重要的优势，因为它的存在促进了磷酸盐的存在，而不是阻碍了磷酸盐的存在，磷酸盐的浓度在生理条件下很高。