Biochemical requirements of bioactive peptides for nutraceutical efficacy

The relationship between diet and health has drawn ever-growing interest. Bioactive peptides are involved in various biological activities, including control of cell proliferation, antimicrobial, antihypertensive, antioxidant, anticholesterolemic, and opioid activity. However, the peptide potential activity is quenched by some factors such as peptide digestion by proteases, cell membrane permeability, and clearance by kidney function. These obstacles to peptide bioavailability are increased for the nutraceutical use of peptides. The aim of this paper is to review the biochemical peculiarities that can improve the nutraceutical use of peptides. The involvement of amino acid sequence, N- and C-terminal groups, and internal chemical modifications of peptide are reported and discussed. In particular, the block of N-terminal group (N-acetylation, or presence of pyroGlu) or/and of C-terminal group (C-amidation), as well as the Ser/Thr/Tyr phosphorylation, prevent the peptide hydrolysis by digestive proteases and give them a better chance to enhance penetration of biological barriers.