Abstract
Recent studies have shown that soybean protein and its peptides have cholesterol-lowering activities. However, it is not clear whether these peptides could overcome physiological barriers, such as phase II metabolism in gastrointestinal tract and poor permeability, to reach the blood stream in its intact form. Therefore, the transepithelial transport characteristics of soybean peptide Trp-Gly-Ala-Pro-Ser-Leu (WGAPSL) with cholesterol- lowering activity were investigated in Caco-2 cells. In this study; the transepithelial absorption of WGAPSL was studied using human intestinal Caco-2 cell monolayers. The results showed that WGAPSL had good stability (83.9% ±1.98%) after simulated gastric and intestinal digestion. During the apical (AP) side to basolateral (BL) side transport, WGAPSL was absorbed intact through Caco-2 cell monolayers with apparent permeability coefficient (Papp) values of 4.4 × 10−8 to 1.2 × 10−8 cm/s. Cytochalasin D loosened the tight junctions of Caco-2 cell monolayers and significantly (p < 0.05) improved the transport process. Sodium azide, wortmannin, and Gly-Pro had minimal effects on transport, demonstrating that the major transport route of WGAPVL was paracellular via tight junctions. Finally, LC-MS analysis showed that Gly-Ala-Pro (GAP) was the important part for the intact absorption of WGAPVL and Trp (W) was the most unstable amino acid residue.
Highlights
After oral administration, food-derived peptides need to overcome two important physiological barriers to be absorbed intact into blood circulation—extensive phase II metabolism in the gastrointestinal tract and poor permeability through the intestinal epithelium [1]
The Cell Counting Kit-8 (CCK-8) assay demonstrated that the WGAPSL peptide was non-toxic for Cytotoxicity in Caco-2 Cells
Caco-2 cells during transport were analyzed by liquid chromatography–mass spectrometry (LC-MS)
Summary
Food-derived peptides need to overcome two important physiological barriers to be absorbed intact into blood circulation—extensive phase II metabolism in the gastrointestinal tract and poor permeability through the intestinal epithelium [1]. A β-casein (193–209) peptide resisted the digestion of brush border membrane peptidases, and its main transport route was transcytosis via internalized vesicles on Caco-2 cell monolayers [8]. Ovomucin had an apparently greater bile acid binding ability than casein which were transported by human H+⁄peptide cotransporters (hPepT1), a main transport system for in Caco-2 cell di-peptides monolayers [16]. The present study investigated hydrolysates (Degree of Hydrolysis18%) were confirmed in a high fat diet mice model [17], while the the sensitivitysequence of WGAPSL to hydrolysis by brush borderusing enzymes and its transepithelial transport of bioactive peptide, WGAPSL, was determined liquid chromatography–mass spectrometry (LC-MS) and reverse phase–high-performance LC (RP-HPLC) [18]. The study investigated the sensitivity of WGAPSL to hydrolysis by brush border enzymes and its
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