BACKGROUNDThe Maillard reaction involves the interaction of various amino acids and reducing sugars, resulting in food browning. It often produces appealing aromas and flavors. The complexities of the reaction are such that it can be challenging to identify the often numerous and frequently volatile products formed by it. In the present study, we sought to identify and evaluate an unusual product with anti‐oxidant activity arising from a fructose‐histidine Maillard reaction model. The anti‐oxidant profile of this product was assessed by computational means.RESULTSThe fructose‐histidine Maillard reaction products (FH‐MRPs) were generated by heating a 2:1 mixture of the sugar and the amino acid at 140 °C for 2 h. Chromatographically separable fractions, labelled DM‐1 to DM‐8, were obtained using silica gel as the stationary phase and dichloromethane/methanol (DCM/MeOH) mixtures as the mobile one. Fraction DM‐5 exhibited the highest 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging activity, and further bio‐assay guided fractionation led to isolation and identification of 1‐(1H‐imidazo[4,5‐c]pyridin‐4‐yl)ethenone (IMPE) as the active principal, the structure of which was established by nuclear magnetic resonance (NMR) spectroscopic and mass spectral techniques. A mechanism for the formation of IMPE from its precursors is proposed. Density functional theory (DFT) calculations suggest this novel heterocyclic compound exerts its anti‐oxidant effects by interacting with DPPH and 2,2'‐Azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) (ABTS) radicals. Essentially, IMPE was non‐toxic below 300 ug mL−1, showing a concentration‐dependent free radical clearance capacity and reducing power within the 100–1000 μg mL−1 range, and moreover, exhibiting significant Fe2+ chelating abilities wihin the 50‐200 μg mL−1 range.CONCLUSIONThis study identified the unique FH‐MRP, IMPE, and found that it acts as food antioxidant through the chelation of metal ions. © 2024 Society of Chemical Industry.

中文翻译：

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1-(1H-咪唑并[4,5-c]吡啶-4-基)乙烯酮（一种源自果糖和组氨酸的美拉德反应产物）的抗氧化活性


背景美拉德反应涉及多种氨基酸和还原糖的相互作用，导致食物褐变。它通常会产生诱人的香气和味道。该反应非常复杂，因此识别由其形成的数量众多且经常挥发的产物可能具有挑战性。在本研究中，我们试图识别和评估果糖-组氨酸美拉德反应模型产生的具有抗氧化活性的不寻常产品。通过计算方法评估了该产品的抗氧化特性。 结果果糖-组氨酸美拉德反应产物（FH-MRP）是通过将糖和氨基酸的2:1混合物在140°C下加热2小时生成的。使用硅胶作为固定相，使用二氯甲烷/甲醇 (DCM/MeOH) 混合物作为流动相，获得了标记为 DM-1 至 DM-8 的色谱可分离馏分。馏分 DM-5 表现出最高的 2,2-二苯基-1-三硝基苯肼 (DPPH) 自由基清除活性，进一步的生物测定指导分级分离导致了 1-(1 H ‐咪唑并[4,5‐ c ]吡啶-4-基）乙烯酮（IMPE）作为活性主体，其结构是通过核磁共振（NMR）光谱和质谱技术确定的。提出了一种从其前体形成 IMPE 的机制。密度泛函理论 (DFT) 计算表明，这种新型杂环化合物通过与 DPPH 和 2,2'-Azino-bis(3-乙基苯并噻唑啉-6-磺酸) (ABTS) 自由基相互作用发挥抗氧化作用。 本质上，低于 300 ug mL 的 IMPE 是无毒的−1 ，在 100–1000 μg/mL 范围内显示出浓度依赖性的自由基清除能力和还原能力−1范围，而且，表现出显着的铁2+螯合能力在 50-200 μg/mL 范围内−1结论本研究鉴定出了独特的FH-MRP、IMPE，并发现它通过金属离子的螯合作用作为食品抗氧化剂。 © 2024 化学工业协会。