Proteins, peptides, and protein hydrolysates as immunomodulatory and antioxidant agents for the formulation of functional foods

Inflammation is the body’s immune response to nonlethal injury involving production of proinflammatory mediators. The inflammatory response can be acute or chronic. An acute response is temporary and is followed by healing while a chronic response is ongoing and may be permanent. However, the production of mediators in an uncontrolled way and in excessive amounts often leads to chronic diseases like atherosclerosis, type 2 diabetes, arthritis, inflammatory bowel disease, and cardiovascular diseases. Despite the significance of chronic inflammation, few drugs have been developed to treat it. Additionally, reactive oxygen species are highly reactive molecules and their production by the body is part of the innate immune reactions and can eliminate invading microorganisms, induce apoptosis in damaged cells, and regulate mediators in cell signaling pathways, making them beneficial in low concentration. However, if uncontrolled, they may have destructive effects on macromolecules such as lipids, proteins and DNA and they may increase the risk for various noncommunicable diseases. Proteins play an important role from a nutritional point of view providing amino acids for protein synthesis. They are also rich sources of bioactive peptides that can be released from the parent protein through hydrolysis. During gastrointestinal digestion or in in vitro hydrolysis, the proteins are hydrolyzed into peptides (and free amino acids) which have high potential to exert multifunctional bioactivities. Depending on their amino acid sequence, bioactive peptides and peptide-rich protein hydrolysates derived from food proteins have shown to exert various health beneficial effects, including antiinflammatory and antioxidant properties. The main objective of this book chapter is to review food-derived bioactive peptides demonstrating these properties. More specifically, their sources, production, structural characteristics, and their mechanisms of action in modulating inflammation and oxidative stress, as well as how these may be applied as potential ingredients for the formulation of functional foods are reviewed.