Editorial [Hot Topic: Food-Derived Bioactive Proteins and Peptides as Potential Components of Nutraceuticals (Executive Editor: H. Meisel)]

In the last two decades fundamental studies have opened a new field of research related to bioactive food components that not only help ensure adequate nutrition, but may provide specific health benefits [for review: 1]. Bioactive components of food origin can be defined as substances, both nutrient and non-nutrient, which may exert regulative activities in the human organism beyond basic nutrition. In particular, food-derived bioactive proteins and peptides are claimed to be health-enhancing components used to reduce the risk of disease or to enhance a certain physiological function. This issue as well as the previous Volume 13, Number 8, 2007, focuses on the advances being achieved in the research on the biochemical properties, physiological effects, production, safety and applications of different bioactive components, with emphasis on milk and egg protein-derived proteins and peptides. Bovine milk and avian eggs contain an array of bioactivities due to proteins and peptides present in active form, such as lysozyme, immunoglobulins, growth factors and hormones. In addition to these fully active components, many bioactivities are latent in that they are inactive within the protein sequence, requiring enzymatic proteolysis for release of bioactive peptides from protein precursors. Bovine milk is currently the main source of a range of bioactive peptides encrypted in major milk proteins [for review: 2]. Activated peptides may exert quite different bioactivities, such as opioid, ACE-inhibitory, immunomodulatory, antimicrobial, mineral binding, antimutagenic and cytomodulatory effects. In the first article, Mine [3] focuses on biological activities of proteins and peptides derived from avian egg, and review their applications in the food and pharmaceutical industries. Several biological activities have been associated with egg components, including anti-microbial, immunomodulatory, anti-cancer and anti-hypertensive activities, anti-adhesive and anti-oxidant properties, protease inhibitors, nutrient bioavailability and functional lipids. In the paper of Shimizu and Dong Ok Son [4] food-derived peptides and intestinal functions are discussed with very interesting considerations. Although dietary peptides are mostly hydrolyzed by digestive enzymes in the intestinal tract, some could be absorbed intact and act in their target organs. Moreover, the intestine is the main target site for functional peptides, i.e. intestine-modulatory peptides can express their functions in the intestinal tract or modulate intestinal epithelial cell functions. These modulatory peptides are showing promising functions in preventing intestinal diseases. The article of Hartmann and Coworkers [5] deals with the assessment of cytotoxic and allergenic potential of bioactive proteins and peptides. When evaluating cytotoxic proteins and peptides of plant and animal origin it is evident that some of these compounds seem to be most effective towards malignant cells leading to the assumption that a cancer protective effect could exist for such bioactive proteins and peptides. Some peptide fragments may conserve part of the allergenicity of the native protein and thus can also be considered as allergens. The data presented on the relationship between the structure of food proteins and peptides and their allergenicity shows the difficulty in trying to assess the “non-allergenicity” of products derived from an allergenic source, even if the process used involved extensive hydrolysis of the native protein. Finally, the paper of Martin and Meisel [6] reviews nucleoprotein-derived and naturally occurring free ribonucleosides as bioactive compounds, including their effects in human cell systems and their functions as marker molecules in cancer disease. Naturally occurring and chemically modified ribonucleosides have interesting bioactive effects, e.g. the ability to enhance gut growth and maturation, to increase iron absorption and to induce apoptosis in human cells. Chemically modified ribonucleosides have already found interesting applications as pharmaceutically active compounds in the treatment of different illnesses. Regarding therapeutic and pharmaceutical aspects, further studies are required to evaluate the bioactive efficacy of indigenous ribonucleosides........