The purpose of this study was to investigate the transepithelial transport and cytoprotective effect of Gln-Ile-Gly-Leu-Phe (QIGLF), an ACE-inhibitory peptide derived from egg white ovalbumin, in human intestinal Caco-2 cell monolayers. The results showed that QIGLF could be absorbed intact through Caco-2 cell monolayers with a P_app value of (9.11 ± 0.19) × 10^–7 cm/s (transport kinetic parameters: K_m, 32.37 ± 12.59 mM; V_max, 1.23 ± 0.49 μM/min cm²). The transport was not significantly decreased by sodium azide and Gly-Pro, an ATP synthesis inhibitor and a peptide transporter 1 (PepT1) substrate, respectively, suggesting that transport of QIGLF was not energy-dependent and carrier-mediated. In addition, wortmannin, a transcytosis inhibitor, had little effect on the transport, suggesting that endocytosis was not involved in the transport of QIGLF. However, the transport of QIGLF was increased significantly in the presence of cytochalasin D, a tight junction disruptor, suggesting that paracellular transport via tight junctions was the major transport mechanism for intact QIGLF across Caco-2 cell monolayers. Moreover, QIGLF was added to Caco-2 cells followed by addition of H₂O₂, and exhibited significant cytoprotective effect in Caco-2 cells against oxidative stress induced by H₂O₂.

中文翻译：

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蛋清ACE抑制肽Gln-Ile-Gly-Leu-Phe在具有细胞保护作用的人肠道Caco-2细胞单层中的运输

这项研究的目的是调查人卵白蛋白中的ACE抑制肽Gln-Ile-Gly-Leu-Phe（QIGLF）在人肠Caco-2细胞单层中的上皮运输和细胞保护作用。结果表明，QIGLF可以通过Caco-2细胞单层完整吸收，P _app值为（9.11±0.19）×10 ^–7 cm / s（传输动力学参数：K _m，32.37±12.59 mM；V _max，1.23 ±0.49μM/ min厘米²）。叠氮化钠和ATP合成抑制剂Gly-Pro和肽转运蛋白1（PepT1）底物的转运没有显着降低，这表明QIGLF的转运不是能量依赖性的，也不是载体介导的。此外，渥曼青霉素，一种胞吞作用抑制剂，对转运几乎没有影响，表明胞吞作用不参与QIGLF的转运。但是，在细胞松弛素D（紧密连接破坏者）的存在下，QIGLF的运输显着增加，这表明通过紧密连接的副细胞运输是完整QIGLF跨Caco-2细胞单层的主要运输机制。此外，将QIGLF加入Caco-2细胞，然后加入H ₂ O ₂，并在Caco-2细胞中对抗H ₂ O ₂诱导的氧化应激表现出显着的细胞保护作用。