Food, Nutrition, and Health Program, Faculty of Land and Food Systems , The University of British Columbia , 2205 East Mall , Vancouver , British Columbia V6T 1Z4 , Canada.
J Agric Food Chem. 2018 Oct 24;66(42):11008-11017. doi: 10.1021/acs.jafc.8b03983. Epub 2018 Oct 15.
Understanding the potential effects of chlorogenic acid (CGA) isomers on the intestinal epithelium is important because coffee intake exposes consumers to the six major CGA isomers: 3-caffeoylquinic acid (3-CQA), 4-caffeoylquinic acid (4-CQA), 5-caffeoylquinic acid (5-CQA), 3,4-dicaffeoylquinic acid (3,4-diCQA), 3,5-dicaffeoylquinic acid (3,5-diCQA), and 4,5-dicaffeoylquinic acid (4,5-diCQA). The present study determined the relative effects of CGA isomers on the antioxidant status of inflamed Caco-2 intestinal cells by investigating the oxidative-stress-responsive pathway and nuclear-factor-erythroid-derived-2-like 2 (Nrf2) signaling. Differentiated Caco-2 cells were challenged with the inflammatory mediators PMA and IFNγ, as a model of intestinal inflammation in vitro. Significant redox ( p < 0.05) responses to these mediators were assessed by indirect measurement of induced generation of reactive oxygen species (ROS), as well as the expression of reduced (GSH) and oxidized (GSSG) glutathione. This translated to a 40% reduction in the GSH/GSSG ratio. We found that responses in these parameters were associated with increased Nrf2 activation ( p < 0.05). ROS generation and increased IL-8 secretion were found in challenged cells, indicating an association between induced oxidation and inflammatory status. Oxidative stress was ameliorated by CGA isomers, which scavenged intracellular ROS, increased GSH, and activated Nrf2 signaling. diCQA isomers were relatively more effective at reducing IL-8 ( p < 0.05). The observed increase in Nrf2 signaling led to upregulated expression of some Nrf2 target genes ( GPX2, KEAP1, and NFE2L2) in Caco-2 cells and activated the Nrf2-Keap1-ARE-signaling pathway. These findings indicate that CGA isomers present in coffee have bioactivity toward alleviating oxidative stress associated with intestinal inflammation.
了解绿原酸(CGA)异构体对肠上皮的潜在影响很重要,因为咖啡的摄入会使消费者接触到六种主要的 CGA 异构体:3-咖啡酰奎尼酸(3-CQA)、4-咖啡酰奎尼酸(4-CQA)、5-咖啡酰奎尼酸(5-CQA)、3,4-二咖啡酰奎尼酸(3,4-diCQA)、3,5-二咖啡酰奎尼酸(3,5-diCQA)和 4,5-二咖啡酰奎尼酸(4,5-diCQA)。本研究通过研究氧化应激反应途径和核因子红细胞衍生 2 样 2(Nrf2)信号,确定了 CGA 异构体对炎症 Caco-2 肠细胞抗氧化状态的相对影响。分化的 Caco-2 细胞受到炎症介质 PMA 和 IFNγ的挑战,作为体外肠道炎症模型。通过间接测量诱导产生的活性氧(ROS)以及还原(GSH)和氧化(GSSG)谷胱甘肽的表达来评估这些介质的显著氧化还原(p<0.05)反应。这导致 GSH/GSSG 比降低了 40%。我们发现这些参数的反应与 Nrf2 激活增加(p<0.05)有关。在受挑战的细胞中发现 ROS 的产生和 IL-8 的分泌增加,表明诱导氧化与炎症状态之间存在关联。CGA 异构体减轻了氧化应激,清除了细胞内的 ROS,增加了 GSH,并激活了 Nrf2 信号。diCQA 异构体在降低 IL-8 方面相对更有效(p<0.05)。观察到的 Nrf2 信号的增加导致 Caco-2 细胞中一些 Nrf2 靶基因(GPX2、KEAP1 和 NFE2L2)的表达上调,并激活了 Nrf2-Keap1-ARE 信号通路。这些发现表明咖啡中存在的 CGA 异构体具有缓解与肠道炎症相关的氧化应激的生物活性。
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