Angiotensin-I-converting enzyme and prolyl endopeptidase inhibitory peptides from natural sources with a focus on marine processing by-products

Like many natural resource-based processing industries, the seafood processing sector gives rise to a significant volume of organic waste. Environmental issues, economic concerns and legal restrictions regarding the disposal of processing wastes have led to increased research in the discovery of alternative value-added products, such as bioactive peptides from these waste streams. Bioactive peptides have various physiological functionalities in the human body following consumption and these include antihypertensive, antiamnesiac, mineral-binding, immunodulatory, antioxidative and antithrombotic activities. The search for bioactive peptides from a variety of different sources has become a major area of research with potential for the functional foods sector. The isolation of bioactive peptides typically involves the hydrolysis of the protein of choice with different proteolytic enzymes, alone or in combination with Generally Recognised as Safe (GRAS) micro-organisms. This review details information on angiotensin I-converting enzyme (ACE) and prolyl endopeptidase (PEP) inhibitors derived from natural, marine and marine processing waste streams and their potential for use as high-value added bioactive peptides.