Abstract
The effect of collagen peptides (CPs) in intestinal mucosal protection has been approved in both cell and animal models. However, its structure–activity relationship and efficient peptide sequences are unclear, which hinders the in-depth study of its action mechanism and relative nutraceuticals and pharmaceuticals development. In this work, size exclusion chromatography, cation-exchange chromatography, and RP-HPLC were used to separate Alaska pollock skin-derived collagen hydrolysates based on their molecular weight, charge property, and hydrophobicity. The intestinal epithelial barrier function (IEBF) protective effect of separated peptide fractions were evaluated by tumor necrosis factor (TNF)-α-induced Caco-2 cell model. Results indicated that lower molecular weight (500–1000 Da) and higher hydrophilicity of CPs were related to better IEBF protective effect. Two high-efficiency IEBF protective peptide sequences, GPSGPQGSR and GPSGLLGPK with the corresponding molecular weights of 841.41 Da and 824.38 Da, were subsequently identified by UPLC-QToF-MS/MS. Their IEBF protective ability are comparable or even better than the currently used intestinal health supplements glutamine and arginine. The present findings suggested that the hydrophilic CPs, with molecular weight between 500 Da to 1000 Da, should be preferred in IEBF protective peptides preparation. GPSGPQGSR and GPSGLLGPK might have the potential of being IEBF protective ingredients used in intestinal health supplements and drugs.
Highlights
The intestine is a specialized organ in which dynamic interactions between host cells and the complex environment occur in addition to food digestion and absorption [1]
We have previously discovered that Alaska pollock skin-derived collagen peptides supplementation could reverse intestinal mucosa dysfunction and correspondingly diminish intestinal and systemic inflammation based on its protective effects on intestinal epithelial tight junction integrity in burned mice model [17]
Trans-epithelial electrical resistance (TEER) and 4 kDa fluorescein isothiocyanate-conjugated dextran (4 kDa FITC-dextran, fluorescein isothiocyanate-conjugated dextran 4 kDa (FD-4)) permeability are two common parameters to indicate the integrity and permeability of cell monolayers, which can be used to appraise the protective effect of collagen peptides on IBEF [24]
Summary
The intestine is a specialized organ in which dynamic interactions between host cells and the complex environment occur in addition to food digestion and absorption [1]. As the first physical barrier, the intestinal epithelial cell layer performs a vital role in against external factors and maintaining intestinal homeostasis, together with the commensal bacteria, the chemical barrier of the mucosal layer, and the cellular immune system [2]. The term “intestinal epithelial barrier function (IEBF)” is used here to refer to the ability of intestinal epithelial cells as a protective barrier that restrict noxious molecules permeation form. Mar. Drugs 2019, 17, 450; doi:10.3390/md17080450 www.mdpi.com/journal/marinedrugs. Mar. Drugs 2019, 17, 450 intestinal lumen to the underlying tissues, while supporting nutrients and water transport.
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