Preparation, receptors, bioactivity and bioavailability of γ-glutamyl peptides: A comprehensive review

The γ-glutamyl peptides refer to a series of bioactive peptides containing γ-glutamyl residues. The unique γ-glutamyl linkage endows γ-glutamyl peptides with higher in vivo stability and longer half-life, which contributes to their potent physiological functions. Recently, γ-glutamyl peptides have become the focus of researchers due to the unique Kokumi taste and various potential bioactivities mediated through activation of the calcium-sensing receptor (CaSR). However, review articles on the emerging bioactivities and potential mechanisms responsible for intestinal absorption of γ-glutamyl peptides are very scanty. This article aimed to discuss the significance and role of γ-glutamyl peptides in human health. The present review systematically summarizes the available scientific information on the preparation, CaSR, bioactivity and bioavailability of food-derived γ-glutamyl peptides. Furthermore, the current scientific challenges and future research directions are also discussed. γ-Glutamyl peptides have been reported to exhibit diverse bioactivities, including anti-inflammatory, hypoglycemic and appetite-suppressing effects as well as the ameliorating effect on colon health, which are attributed to CaSR activation. Moreover, due to the high resistance towards gastrointestinal digestion, γ-glutamyl peptides can play a key role in the gastrointestinal tract and also be transported across the intestinal epithelium mainly via peptide transporter 1 (PepT1) or paracellular routes to exhibit various in vivo activities. In addition, further and intensive investigations are urgently required to address the current challenges pertaining to the effective preparation, novel physiological functions and exact absorption mechanisms of γ-glutamyl peptides. This review contributes to a better understanding of γ-glutamyl peptides in terms of their cellular receptor, bioactivity and bioavailability.