Fan Jing, Li Tie-Jing, Zhao Xin-Huai
Key Laboratory of Dairy Science, Ministry of Education, Northeast Agricultural University 150030 Harbin PR China
College of Light Industry, Liaoning University 110136 Shenyang PR China
RSC Adv. 2020 Jul 21;10(46):27249-27258. doi: 10.1039/d0ra04162a.
Polyphenols are beneficial to human health because of their bio-activities. In this study, two flavonols quercetin and myricetin with or without heat treatment at 100 °C for 30 min were assessed for their barrier-promoting efficiency in rat intestinal epithelial (IEC-6) cells. The results indicated that the heated and unheated flavonols at dose levels of 2.5-20 μmol L had a nontoxic effect on the cells treated for 24 and 48 h but enhanced the values of cell viability larger than 100% (especially at a dose level of 5 μmol L). Moreover, the cells exposed to these flavonols of 5 μmol L for 24 and 48 h had improved barrier integrity compared to the control cells without any flavonol treatment, reflected by enhanced transepithelial electrical resistance and anti-bacterial effect but decreased paracellular permeability and bacterial translocation. Moreover, the results from both mRNA and protein expression verified 1.1-3.4 fold up-regulation of zonula occludens-1, occludin, and claudin-1 that are critical to tight junctions and barrier function of cells. Furthermore, the expression of other two proteins RhoA and ROCK in the treated cells was also down-regulated, demonstrating suppressed Rho activation and consequently barrier promotion the RhoA/ROCK signaling pathway. Overall quercetin, due to its lower molecular polarity, mostly gave higher barrier-promoting efficiency than myricetin, while the heated flavonols were always less efficient than the unheated counterparts to promote barrier integrity of IEC-6 cells. It is thus highlighted that flavonols can provide barrier-promoting effects on intestinal epithelial cells with a promoting efficiency dependent on flavonol polarity; however, heat treatment especially excessive heat treatment of plant foods might lead to damaged flavonol activity.
多酚因其生物活性而对人体健康有益。在本研究中，评估了两种黄酮醇槲皮素和杨梅素在100℃热处理30分钟或未热处理的情况下，对大鼠肠上皮（IEC-6）细胞屏障促进效率的影响。结果表明，剂量水平为2.5-20μmol/L的加热和未加热黄酮醇对处理24小时和48小时的细胞无毒作用，但提高了细胞活力值，使其大于100%（尤其是在5μmol/L的剂量水平）。此外，与未用任何黄酮醇处理的对照细胞相比，暴露于5μmol/L这些黄酮醇24小时和48小时的细胞屏障完整性得到改善，表现为跨上皮电阻增强和抗菌作用，但细胞旁通透性降低和细菌易位减少。此外，mRNA和蛋白质表达结果均证实，对细胞紧密连接和屏障功能至关重要的闭合蛋白-1、闭合蛋白和紧密连接蛋白-1上调了1.1-3.4倍。此外，处理细胞中其他两种蛋白质RhoA和ROCK的表达也下调，表明Rho激活受到抑制，从而促进了RhoA/ROCK信号通路的屏障功能。总体而言，由于槲皮素分子极性较低，其屏障促进效率大多高于杨梅素，而加热的黄酮醇在促进IEC-6细胞屏障完整性方面总是比未加热的黄酮醇效率低。因此，突出显示黄酮醇可对肠上皮细胞提供屏障促进作用，促进效率取决于黄酮醇的极性；然而，植物性食物的热处理，尤其是过度热处理，可能会导致黄酮醇活性受损。
