Department of Metabolism and Nutrition, Instituto del Frío-ICTAN, Consejo Superior de Investigaciones Científicas, José Antonio Novais 10, Ciudad Universitaria, 28040 Madrid, Spain.
J Nutr Biochem. 2011 Dec;22(12):1186-94. doi: 10.1016/j.jnutbio.2010.10.005. Epub 2011 Feb 21.
Humans are exposed to dietary acrylamide (AA) during their lifetime; it is therefore necessary to investigate the mechanisms associated with AA induced toxic effects. Accumulating evidence indicates that oxidative stress may contribute to AA cytotoxicity, but the link between oxidative stress and AA cytotoxicity in the gastrointestinal tract, the primary organ in contact with dietary AA, has not been described. In this study, we evaluate the alterations of the redox balance induced by AA in Caco-2 intestinal cells as well as the potential protective role of natural antioxidants such as a well-standardized cocoa polyphenolic extract (CPE) and its main polyphenol components epicatechin (EC) and procyanidin B2 (PB2). We found that AA-induced oxidative stress in Caco-2 cells is evidenced by glutathione (GSH) depletion and reactive oxygen species (ROS) overproduction. AA also activated the extracellular-regulated kinases and the c-Jun N-amino terminal kinases (JNKs) leading to an increase in caspase-3 activity and cell death. Studies with appropriate inhibitors confirmed the implication of oxidative stress and JNKs activation in AA-induced apoptosis. Additionally, AA cytotoxicity was counteracted by CPE or PB2 by inhibiting GSH consumption and ROS generation, increasing the levels of gamma-glutamyl cysteine synthase and glutathione-S-transferase and blocking the apoptotic pathways activated by AA. Therefore, AA-induced cytotoxicity and apoptosis are closely related to oxidative stress in Caco-2 cells. Interestingly, natural dietary antioxidant such as PB2 and CPE were able to suppress AA toxicity by improving the redox status of Caco-2 cells and by blocking the apoptotic pathway activated by AA.
人类在其一生中都会接触到膳食丙烯酰胺（AA）；因此，有必要研究与 AA 诱导的毒性作用相关的机制。越来越多的证据表明，氧化应激可能与 AA 的细胞毒性有关，但在与膳食 AA 接触的主要器官——胃肠道中，氧化应激与 AA 细胞毒性之间的联系尚未描述。在这项研究中，我们评估了 AA 在 Caco-2 肠细胞中引起的氧化还原平衡的改变，以及天然抗氧化剂（如标准化可可多酚提取物（CPE）及其主要多酚成分表儿茶素（EC）和原花青素 B2（PB2））的潜在保护作用。我们发现，AA 诱导的 Caco-2 细胞氧化应激表现为谷胱甘肽（GSH）耗竭和活性氧（ROS）过度产生。AA 还激活了细胞外调节激酶和 c-Jun N-末端激酶（JNKs），导致 caspase-3 活性增加和细胞死亡。适当抑制剂的研究证实了氧化应激和 JNKs 激活在 AA 诱导的细胞凋亡中的作用。此外，CPE 或 PB2 通过抑制 GSH 消耗和 ROS 生成、增加γ-谷氨酰半胱氨酸合成酶和谷胱甘肽-S-转移酶的水平以及阻断 AA 激活的凋亡途径，拮抗 AA 的细胞毒性。因此，AA 诱导的细胞毒性和凋亡与 Caco-2 细胞中的氧化应激密切相关。有趣的是，天然膳食抗氧化剂如 PB2 和 CPE 能够通过改善 Caco-2 细胞的氧化还原状态和阻断 AA 激活的凋亡途径来抑制 AA 的毒性。
