Interactions of flavonoids with iron and copper ions:: A mechanism for their antioxidant activity
Interactions of flavonoids with iron and copper ions:: A mechanism for their antioxidant activity
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DOI：
10.1080/1071576021000016463
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发表时间：
2002-11-01
影响因子：
3.3
通讯作者：
Jennings, KR
中科院分区：
文献类型：
--
作者：
Mira, L;Fernandez, MT;Jennings, KR
黄酮类化合物的金属螯合特性表明，它们可能在金属过载疾病和涉及过渡金属离子的所有氧化应激条件下发挥作用。本文详细研究了黄酮类化合物对铁(包括Fe3+)和铜离子的络合能力及其结构和pH的依赖关系。酸性介质在某些病理条件下可能是重要的。此外，还研究了黄酮类化合物还原铁离子和铜离子的能力及其活性与构效关系。为了实现这些目标，研究了黄酮类(芹菜素、木犀草素、山奈酚、槲皮素、杨梅素和芦丁)、异黄酮类(大豆苷元和染料木素)、黄烷酮类(紫杉林、柚皮苷和柚皮苷)和黄烷醇(儿茶素)。所研究的所有黄酮类化合物对铜离子的还原能力都高于对铁离子的还原能力。具有较好的还原Fe3+活性的黄酮类化合物具有2，3-双键，并且在B-环上同时具有邻苯二酚基团和3-羟基基团。铜的还原活性似乎在很大程度上取决于羟基的数目，用紫外光谱和电喷雾电离质谱仪对络合作用进行了研究。只有黄酮类和黄烷醇儿茶素与金属离子相互作用。在pH为7.4和5.5时，所研究的所有黄酮类化合物似乎都在相同的位置上与Cu2+发生螯合作用，可能是在5-羟基和4-氧基之间。然而，在pH 7.4时，杨梅素和栎素似乎在邻儿茶酚基团上额外螯合Cu2+，邻儿茶酚基团是儿茶素在pH 7.4时与Cu2+的螯合部位。只有在pH为5.5的条件下，才对Fe3+与类黄酮的络合作用进行了研究。在3位上，杨梅素和槲皮素与铁发生强烈的相互作用，5-羟基和4-氧基之间可能再次发生络合作用。它们的行为可以用它们在pH 5.5时还原Fe3+的能力来解释，这表明类黄酮类化合物在结合之前将Fe3+还原为Fe2+。
The metal chelating properties of flavonoids suggest that they may play a role in metal-overload diseases and in all oxidative stress conditions involving a transition metal ion. A detailed study has been made of the ability of flavonoids to chelate iron (including Fe3+) and copper ions and its dependence of structure and pH. The acid medium may be important in some pathological conditions. In addition, the ability of flavonoids to reduce iron and copper ions and their activity-structure relationships were also investigated. To fulfil these objectives, flavones (apigenin, luteolin, kaempferol, quercetin, myricetin and rutin), isoflavones (daidzein and genistein), flavanones (taxifolin, naringenin and naringin) and a flavanol (catechin) were investigated. All flavonoids studied show higher reducing capacity for copper ions than for iron ions. The flavonoids with better Fe3+ reducing activity are those with a 2,3-double bond and possessing both the catechol group in the B-ring and the 3-hydroxyl group. The copper reducing activity seems to depend largely on the number of hydroxyl groups, The chelation studies were carried out by means of ultraviolet spectroscopy and electrospray ionisation mass spectrometry. Only flavones and the flavanol catechin interact with metal ions. At pH 7.4 and pH 5.5 all flavones studied appear to chelate Cu2+ at the same site, probably between the 5-hydroxyl and the 4-oxo groups. Myricetin and quercetin, however, at pH 7.4, appear to chelate Cu2+ additionally at the ortho-catechol group, the chelating site for catechin with Cu2+ at pH 7.4. Chelation studies of Fe3+ to flavonoids were investigated only at pH 5.5. On 3 myricetin and quercetin interact strongly with Fe, complexation probably occurring again between the 5-hydroxyl and the 4-oxo groups. Their behaviour can be explained by their ability to reduce Fe3+ at pH 5.5, suggesting that flavonoids reduce Fe3+ to Fe2+ before association.