This study evaluated transepithelial transport mechanisms of Ile-Gln-Pro (IQP) and Val-Glu-Pro (VEP), two ACE-inhibitory peptides derived from Spirulina platensis, using human intestinal Caco-2 cell monolayers. IQP and VEP were absorbed intact through Caco-2 cell monolayers with Papp values of 7.48 ± 0.58 × 10-6 and 5.05 ± 0.74 × 10-6 cm/s, respectively. The transport of IQP and VEP were affected neither by Gly-Pro nor by wortmannin, indicating that they were not PepT1-mediated and did not involve endocytosis. However, transport of IQP and VEP were increased significantly by sodium deoxycholate, suggesting that the major transport mechanism was paracellular. In addition, the increased transport of VEP and IQP were followed with the addition of sodium azide, suggesting influence of energy to the process. The transport of VEP was also increased by verapamil, indicating an apical-to-basolateral flux mediated by P-gp. PRACTICAL APPLICATION Bioactive peptides derived from food proteins have been considered as potentially ideal products to reduce hypertension because of their safety and positive impacts on health. IQP and VEP are the 2 ACE inhibitory peptides derived from Spirulina platensis, a kind of edible cyanobacteria with rich nutrition and multiple physiological functions, and were demonstrated to inhibit ACE and lower blood pressure in spontaneously hypertensive rats. However, it is prerequisite that such bioactive peptides must be absorbed intact across the intestinal epithelium, so as to exert antihypertensive effects in vivo. This study evaluated transepithelial transport mechanisms of IQP and VEP. It contributes to the study of Spirulina in lowering blood pressure and supports the development of bioactive peptide products.

中文翻译：

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源自螺旋藻的 ACE 抑制肽 Ile-Gln-Pro 和 Val-Glu-Pro 跨 Caco-2 单层的转运

本研究使用人肠道 Caco-2 细胞单层评估了 Ile-Gln-Pro (IQP) 和 Val-Glu-Pro (VEP) 这两种源自 Spirulina platensis 的 ACE 抑制肽的跨上皮转运机制。IQP 和 VEP 通过 Caco-2 细胞单层被完整吸收，Papp 值分别为 7.48 ± 0.58 × 10-6 和 5.05 ± 0.74 × 10-6 cm/s。IQP 和 VEP 的转运不受 Gly-Pro 和 wortmannin 的影响，表明它们不是 PepT1 介导的，也不涉及内吞作用。然而，去氧胆酸钠显着增加了 IQP 和 VEP 的转运，这表明主要的转运机制是细胞旁的。此外，随着叠氮化钠的添加，VEP 和 IQP 的传输增加，表明能量对过程的影响。维拉帕米也增加了 VEP 的转运，表明由 P-gp 介导的从顶端到基底外侧的通量。实际应用 源自食物蛋白的生物活性肽因其安全性和对健康的积极影响而被认为是降低高血压的潜在理想产品。IQP 和 VEP 是源自螺旋藻的 2 种 ACE 抑制肽，螺旋藻是一种营养丰富且具有多种生理功能的可食用蓝藻，被证明可抑制自发性高血压大鼠的 ACE 和降低血压。然而，前提条件是此类生物活性肽必须完整地被肠上皮吸收，才能在体内发挥抗高血压作用。本研究评估了 IQP 和 VEP 的跨上皮转运机制。