Key Laboratory of Dairy Science, Ministry of Education, Northeast Agricultural University, Harbin, PR China.
Key Laboratory of Dairy Science, Ministry of Education, Northeast Agricultural University, Harbin, PR China; School of Biology and Food Engineering, Guangdong University of Petrochemical Technology, Maoming, PR China.
J Nutr Biochem. 2021 Jan;87:108517. doi: 10.1016/j.jnutbio.2020.108517. Epub 2020 Oct 2.
Flavonols are bioactive substances in plant foods. In this study, two flavonols galangin and kaempferol were heated at 100°C for 30 min prior to assessing their effects on barrier function of rat intestinal epithelial (IEC-6) cells. Both heated and unheated flavonols (2.5-20 µmol/L dosages) were nontoxic to the cells up to 48 h post-treatment, and could promote cell viability values to 102.2-141.2% of control. By treatment with 5 µmol/L flavonols for 24 and 48 h, the treated cells time-dependently showed better improved physical and biological barrier functions than the control cells without any flavonol treatment, including higher transepithelial electrical resistance and antibacterial effect but reduced paracellular permeability and bacterial translocation. The results from real-time PCR and western-blot assays indicated that the cells treated with heated and unheated flavonols of 5 µmol/L dosage had up-regulated mRNA (1.13-1.81 folds) and protein (1.15-5.11 folds) expression for zonula occluden-1, occludin, and claudin-1 that are vital to the tight junctions of the cells. Moreover, protein expression of RhoA and ROCK were down-regulated into 0.41-0.98 and 0.40-0.92 folds, respectively, demonstrating a Rho inactivation that led to enhanced cell barrier integrity via the RhoA/ROCK pathway. Overall, galangin was more active than kaempferol to perform three biofunctions like improving cell barrier function, up-regulating tight junctions protein expression, and down-regulating RhoA/ROCK expression. Moreover, the heated flavonols were less effective than the unheated counterparts to perform these biofunctions. It is concluded that this heat treatment of galangin and kaempferol could inhibit their benefits to improve barrier function of IEC-6 cells.
类黄酮是植物性食物中的生物活性物质。在这项研究中，在评估加热 30 分钟前后的两种类黄酮（高良姜素和山柰酚）对大鼠肠上皮（IEC-6）细胞屏障功能的影响之前，将它们加热至 100°C。加热和未加热的类黄酮（2.5-20 µmol/L 剂量）在处理后 48 小时内对细胞均无毒性，可将细胞活力值提高到对照的 102.2-141.2%。用 5 µmol/L 类黄酮处理 24 和 48 小时后，与未用任何类黄酮处理的对照细胞相比，处理过的细胞时间依赖性地显示出更好的改善物理和生物屏障功能，包括更高的跨上皮电阻和抗菌作用，但降低了细胞旁通透性和细菌易位。实时 PCR 和 Western blot 分析的结果表明，用 5 µmol/L 剂量的加热和未加热的类黄酮处理的细胞上调了细胞间紧密连接至关重要的 zonula occluden-1、occludin 和 claudin-1 的 mRNA（1.13-1.81 倍）和蛋白（1.15-5.11 倍）表达。此外，RhoA 和 ROCK 的蛋白表达分别下调至 0.41-0.98 和 0.40-0.92 倍，表明 Rho 失活通过 RhoA/ROCK 通路增强了细胞屏障完整性。总的来说，高良姜素比山柰酚更活跃，能发挥改善细胞屏障功能、上调紧密连接蛋白表达和下调 RhoA/ROCK 表达等三种生物功能。此外，加热的类黄酮在发挥这些生物功能方面的效果不如未加热的类黄酮。结论是，这种对高良姜素和山柰酚的热处理可能会抑制它们改善 IEC-6 细胞屏障功能的益处。
