Food Protein-Derived Antioxidant Peptides: Molecular Mechanism, Stability and Bioavailability

Abstract

The antioxidant activity of protein-derived peptides was one of the first to be revealed among the more than 50 known peptide bioactivities to date. The exploitation value associated with food-derived antioxidant peptides is mainly attributed to their natural properties and effectiveness as food preservatives and in disease prevention, management, and treatment. An increasing number of antioxidant active peptides have been identified from a variety of renewable sources, including terrestrial and aquatic organisms and their processing by-products. This has important implications for alleviating population pressure, avoiding environmental problems, and promoting a sustainable shift in consumption. To identify such opportunities, we conducted a systematic literature review of recent research advances in food-derived antioxidant peptides, with particular reference to their biological effects, mechanisms, digestive stability, and bioaccessibility. In this review, 515 potentially relevant papers were identified from a preliminary search of the academic databases PubMed, Google Scholar, and Scopus. After removing non-thematic articles, articles without full text, and other quality-related factors, 52 review articles and 122 full research papers remained for analysis and reference. The findings highlighted chemical and biological evidence for a wide range of edible species as a source of precursor proteins for antioxidant-active peptides. Food-derived antioxidant peptides reduce the production of reactive oxygen species, besides activating endogenous antioxidant defense systems in cellular and animal models. The intestinal absorption and metabolism of such peptides were elucidated by using cellular models. Protein hydrolysates (peptides) are promising ingredients with enhanced nutritional, functional, and organoleptic properties of foods, not only as a natural alternative to synthetic antioxidants.

Keywords: antioxidant activity; bioactive peptides; food applications; food sources; molecular mechanism; stability and bioavailability.

Figure 1

The main food-based sources of antioxidant active peptides.

Figure 2

Schematic showing the regulatory mechanism of the Keap1-Nrf2-ARE pathway. Under normal physiological conditions, the Keap1 dimer binds to two binding motifs, called DLG and ETGE, in a specific domain of Nrf2, allowing Nrf2 to be sequestered in the cell membrane and maintained at low levels by Keap1-dependent ubiquitination and proteasomal degradation. Under oxidative stress, such as the presence of reactive oxygen species (ROS), the conformation of Keap1 changes, resulting in the release of Nrf2 from Keap1-directed degradation, which translocates in the nucleus and forms a dimer in sMAF. The polymer formed leads to the induction of ARE-dependent genes such as Sod, Cat, Gpx, and Gcl. These gene products subsequently exert cytoprotection against ROS. Ub, ubiquitin.

Figure 3

Underlying mechanisms of transcortical transport of peptides with diverse sizes. (1) H+-coupled PepT1 and 2; (2) Na+-coupled SOPT1 and 2; (3) paracellular; (4) transcytosis. Pep, peptide.