Antioxidant Activity of Proteins and Peptides

Abstract

Proteins can inhibit lipid oxidation by biologically designed mechanisms (e.g. antioxidant enzymes and iron-binding proteins) or by nonspecific mechanisms. Both of these types of antioxidative proteins contribute to the endogenous antioxidant capacity of foods. Proteins also have excellent potential as antioxidant additives in foods because they can inhibit lipid oxidation through multiple pathways including inactivation of reactive oxygen species, scavenging free radicals, chelation of prooxidative transition metals, reduction of hydroperoxides, and alteration of the physical properties of food systems. A protein's overall antioxidant activity can be increased by disruption of its tertiary structure to increase the solvent accessibility of amino acid residues that can scavenge free radicals and chelate prooxidative metals. The production of peptides through hydrolytic reactions seems to be the most promising technique to form proteinaceous antioxidants since peptides have substantially higher antioxidant activity than intact proteins. While proteins and peptides have excellent potential as food antioxidants, issues such as allergenicity and bitter off-flavors as well as their ability to alter food texture and color need to be addressed.

Tryptophan-containing milk protein-derived dipeptides inhibit xanthine oxidase

“…Our results showed no effect of the position of the Trp residue in the dipeptide on XO inhibition, suggesting that the N or C-terminal location of Trp does not affect its bioactivity. Amino acids have been reported to display a lower anti-oxidant activity compared to peptides as they have a lower radical scavenging activity [19]. In contrast, we found that Trp displayed a similar XO IC 50 inhibition has yet to be fully determined [79] No XO inhibition was observed with hydrolyzates of complex protein substrates such as WPI, WPI Ret and NaCN.…”

“…Certain amino acid structures have been correlated with high antioxidant properties. These include amino acids with sulfur residues (Cys and Met) and aromatic structures (Trp, Tyr, His and Phe) [19,48,60,73,75]. Phenol and indole groups in amino acids can act as potential hydrogen donors [70,73,75].…”

“…Milk proteins, peptide sequences encrypted within the primary structures of the milk proteins and amino acids have also been associated with the regulation of postprandial glycaemia and insulin secretion in normoglycaemic and type 2 diabetic subjects [24,26,56,57,61,72]. Different studies have demonstrated the anti-oxidative role of milk proteins and peptides [19,53,70,75,83]. A fraction from human milk enriched in Trp has been identified for its high scavenging activity in vitro [84].…”

Changes in antioxidant activities and physicochemical properties of Kapi, a fermented shrimp paste, during fermentation

“…Moreover, the proliferation of short chain peptides and amino acids generated from protein hydrolysis showed potential effects on inhibition of lipid oxidation via scavenging free radical and reduction of hydroperoxide (Elias et al 2008). …”

Radical scavenging and amino acid profiling of wedge clam, Donax cuneatus (Linnaeus) protein hydrolysates

“…On the other hand oxidative reactions in foods lead to the deterioration of quality attributes such as flavor, aroma, texture, and color (Park et al 2001). In lipid peroxidation, these reactions typically involve free radical pathways that result in the formation of lipid hydroperoxides, which are eventually decomposed to low molecular weight carbonyls in the presence of prooxidants (Elias et al 2008). A potent scavenger of these species may serve as a possible preventive intervention for free radical mediated diseases (Gutteridge and Halliwell 2010).…”