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首页> 外文期刊>Journal of mass spectrometry: JMS >Structure and antioxidant activity of brominated flavonols and flavanones
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Structure and antioxidant activity of brominated flavonols and flavanones

机译：溴化黄酮醇和黄烷酮的结构和抗氧化活性

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摘要

Hypobromous acid (HOBr) produced by both eosinophil peroxidase (EPO) and myeloperoxidase (MPO) is a stronger oxidant than HOCl, and is also essential for optimal and efficient microbial killing. Considering the potential cytotoxic effect of HOBr, if it is formed outside the phagosome, it should be useful to scavenge it in order to protect the nearby tissues. In this study the ability of selected flavonoids to protect against HOBr mediated oxidation reactions was performed through a competitive reaction, and the resulting products identified by high performance liquid chromatography (HPLC) and electrospray ionization tandem mass spectrometry(ESI-MS/MS). Several structural features were found to be important to confer high antioxidant activity to flavonoids towards HOBr: the C2 = C3 double bond and the 3-OH group in the C-ring, and the presence of both 5-OH and 7-OH groups in the A-ring. The MS results showed that flavonoids are dibrominated in the A-ring, suggesting that (except for fisetin) bromination occurs at C6 and C8 positions, through an electrophilic aromatic substitution reaction. The chemical modifications achieved by bromination of flavonoids have changed their biological properties, presenting their brominated derivatives higher antioxidant activity, as radical scavengers, and higher lipophilicity, than the parent flavonoids. Brominated flavonoids may then diffuse easily through membranes increasing the intracellular concentration of the compounds. These locally formed metabolites may also interact with signaling cascades involving cytokines and regulatory transcription factors, thus playing a role in inflammation and in the regulation of immune response.
机译：嗜酸性粒细胞过氧化物酶（EPO）和髓过氧化物酶（MPO）产生的次溴酸（HOBr）是比HOCl更强的氧化剂，对于最佳和有效地杀灭微生物也是必不可少的。考虑到HOBr的潜在细胞毒性作用，如果它在吞噬体外部形成，则清除它应该是有用的，以保护附近的组织。在这项研究中，通过竞争性反应来研究所选黄酮类化合物防御HOBr介导的氧化反应的能力，并通过高效液相色谱（HPLC）和电喷雾电离串联质谱（ESI-MS / MS）鉴定所得产物。发现一些结构特征对于赋予黄酮类化合物高抗HOBr活性很重要：C2 = C3双键和C环中的3-OH基团，以及在C-环中同时存在5-OH和7-OH基团。 A形圈。 MS结果表明，类黄酮在A环中被二溴化，这表明（非西汀除外）溴化发生在C6和C8位置，这是通过亲电子芳香取代反应引起的。通过黄酮类化合物的溴化而实现的化学修饰改变了它们的生物学特性，从而使其溴化衍生物比母体类黄酮具有更高的抗氧化剂活性（作为自由基清除剂）和更高的亲脂性。然后，溴化类黄酮可能会容易地通过膜扩散，从而增加化合物的细胞内浓度。这些局部形成的代谢物也可能与涉及细胞因子和调节转录因子的信号级联反应相互作用，从而在炎症和免疫应答调节中起作用。

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