Milk Protein-derived Bioactive Peptides Research Articles

Dairy Milk Protein-Derived Bioactive Peptides: Avengers Against Metabolic Syndrome.

Metabolic syndrome is continuously increasing among the world's populations. Metabolic syndrome is a medical condition in which individuals suffer from high blood pressure, high blood glucose levels, and obesity. The in vitro and in vivo bioactivities of dairy milk protein-derived peptides (MPDP) have proven their potential as an excellent natural alternative to the current medical treatment for metabolic syndrome. In this context, the review discussed the major protein source of dairy milk and provides current knowledge on the novel and integrated approach to MPDP production. A detailed comprehensive discussion is provided on the current state of knowledge regarding the in vitro and in vivo bioactivities of MPDP against metabolic syndrome. In addition, the most important aspect of digestive stability, allergenicity, and further directions for MPDP application is provided. The major proteins found in milk are casein and whey, while a minor portion of serum albumin and transferrin are reported. Upon gastrointestinal digestion or enzymatic hydrolysis, these proteins produce peptides with various biological activities including antioxidative, antiinflammatory, antihypertensive, antidiabetic, and antihypercholesterolemic, which could help in ameliorating metabolic syndrome. Bioactive MPDP has the potential to curtail metabolic syndrome and potentially act as a safe replacement for chemical drugs with fewer side effects.

A novel human milk protein-derived peptide BCCY-1 exerts immunomodulatory effects on monocytes through NF-κB and MAPK signaling pathways

Abstract Protective effects of breastfeeding in reducing childhood infection have been reported. Human breast milk contains diverse bioactive compounds with direct and indirect antimicrobial activities as well as molecules that modulate the immune system. Although some of the molecules involved in human milk’s beneficial effects on development of immune function have been studied, the role of specific milk component in immunomodulation is not yet clear. Milk protein-derived bioactive peptides have been identified with various health-promoting functions icluding immunoregulation. In the present study, we found that a peptide derived from human milk protein β-casein (BCCY-1) enhance the migration of monocytes without affecting cell proliferation and apoptosis. In addition, BCCY-1 induced the chemokine production via activition of NF-κB and MAPK signaling pathways, which could be blocked by specific inhibitors of NF-κB and MAPK. Moreover, the relative intensity of peptide BCCY-1 as well as a cluster of β-casein derived peptides comprising a fragment of BCCY-1 were decreased in the preterm breast milk compared with the term breast milk, indicating a potential role of BCCY-1 and the similar sequences under physiological condition. Identification of those peptides and their physiological functions are necessary to transfer their potent functional properties into food or potential applications in health-care. This study highlight the important role of β-casein derived peptides in the immunomodulatory effects of human breast milk and suggest a promising way to develop novel dietary supplements, foods and even pharmaceutical agents.

Application of in silico approaches for the generation of milk protein-derived bioactive peptides

Abstract Milk protein derived peptides have numerous well-documented bioactive properties. The conventional approach for the generation, identification and validation of bioactive peptides (BAPs) has involved (i) protein hydrolysis, (ii) bioactivity screening and (iii) validation in vivo. The low potency (in comparison to conventional drugs), susceptibility to breakdown during gastrointestinal transit and low intestinal permeability are key challenges in the development of highly bioactive food protein hydrolysates/peptides. However, the generation of potent and effective health enhancing hydrolysates/peptides can benefit from a range of in silico techniques including the application of structure bioactivity relationship modelling (e.g., quantitative structure activity relationship (QSAR) modelling), molecular docking and design of experiments (DOE) approaches to optimise BAP production and identification. Some examples of how these approaches have been employed in BAP discovery and generation will be outlined.

Effect of Milk Protein Hydrolysate on Some Hematological Parameters of Type II Diabetic Rats

Milk protein-derived bioactive peptides could be used in human nutrition in both newborns and adults, since they are claimed to be health-improving components that can be used to reduce the risk of disease or to enhance certain physiological functions. This study investigated the effect of oral intake of milk protein concentrate (MPC) and milk protein concentrate hydrolysate (MPCH) on body weight, organ relative weight, and hematological parameters in alloxan-induced diabetes rats. The animals were divided into six major groups after stabilization of diabetes for one week. Diabetic and non-diabetic rats groups were received intra-gastric dose of MPC or MPCH (150mg/kg B.W) for six weeks. Feed treatment by MPC and MPCH significantly (<i>P</i><0.05) increased the final body weight of normal rats and improved the body weight of diabetic rats and significantly protective (<i>P</i><0.05) the liver, kidney, heart and lung of normal rats and reduced the fallers of these organs in diabetic rats. The diabetes groups treated by MPCH showed improvement in RBC, Hb, Ht and PLT values. Meanwhile WBC not affected. The oral intake of MPCH protected the normal range of Lymphocytes and S. Nutrophils in healthy and diabetic rats. The oral intake of MPCH caused significant (<i>P</i><0.05) decrease of Monocytes in diabetic and non-diabetic rats, while the oral intake of MPC had no affected on Monocytes of diabetic and non-diabetic rats. MPC and MPCH reduced the harmful effect of T2D on body weight, organs weights of rats, and improvement most hematological parameters of normal and diabetes rats.

Lactotripeptide ingestion increases cerebral blood flow velocity in middle-aged and older adults

The age-related decrease in cerebral blood flow velocity increases the risk of cerebrovascular disease. Milk protein-derived bioactive peptides, e.g., lactotripeptide (LTP), have been shown to inhibit angiotensin converting enzyme activities and increase vasodilator production. We hypothesized that LTP ingestion increases cerebral blood flow velocity in middle-aged and older adults. In a randomized, placebo-controlled, double-blind design, 15 healthy middle-aged and older adults were assigned to either a LTP group or a placebo group. The subjects ingested LTP or placebo orally for 8 weeks. Before and after intervention, middle cerebral blood flow velocity was measured using transcranial Doppler ultrasonography. The baseline middle cerebral blood flow velocity and most other key dependent variables did not differ between the groups. LTP ingestion significantly increased middle cerebral blood flow velocity, but there was no such improvement in the placebo groups. We concluded that 8 weeks of LTP ingestion increased middle cerebral blood flow velocity in middle-aged and older adults.

Enhancing bioactive peptide release and identification using targeted enzymatic hydrolysis of milk proteins.

Milk proteins have been extensively studied for their ability to yield a range of bioactive peptides following enzymatic hydrolysis/digestion. However, many hurdles still exist regarding the widespread utilization of milk protein-derived bioactive peptides as health enhancing agents for humans. These mostly arise from the fact that most milk protein-derived bioactive peptides are not highly potent. In addition, they may be degraded during gastrointestinal digestion and/or have a low intestinal permeability. The targeted release of bioactive peptides during the enzymatic hydrolysis of milk proteins may allow the generation of particularly potent bioactive hydrolysates and peptides. Therefore, the development of milk protein hydrolysates capable of improving human health requires, in the first instance, optimized targeted release of specific bioactive peptides. The targeted hydrolysis of milk proteins has been aided by a range of in silico tools. These include peptide cutters and predictive modeling linking bioactivity to peptide structure [i.e., molecular docking, quantitative structure activity relationship (QSAR)], or hydrolysis parameters [design of experiments (DOE)]. Different targeted enzymatic release strategies employed during the generation of milk protein hydrolysates are reviewed herein and their limitations are outlined. In addition, specific examples are provided to demonstrate how in silico tools may help in the identification and discovery of potent milk protein-derived peptides. It is anticipated that the development of novel strategies employing a range of in silico tools may help in the generation of milk protein hydrolysates containing potent and bioavailable peptides, which in turn may be used to validate their health promoting effects in humans. Graphical abstract The targeted enzymatic hydrolysis of milk proteins may allow the generation of highly potent and bioavailable bioactive peptides.

Milk bioactive peptide database: A comprehensive database of milk protein-derived bioactive peptides and novel visualization

During processing and digestion, milk proteins are disassembled into peptides with an array of biological functions, including antimicrobial, angiotensin-converting enzyme inhibition, antioxidant, opioid, and immunomodulation. These functions are summarized in numerous reviews, yet information on which peptides have which functions remains scattered across hundreds of research articles. We systematically searched the literature for all instances of bioactive peptides derived from milk proteins from any mammalian source. The data were compiled into a comprehensive database, which can be used to search for specific functions, peptides, or proteins (http://mbpdb.nws.oregonstate.edu). To review this large dataset, the bioactive peptides reported in the literature were visually mapped on the parent protein sequences, providing information on sites with highest abundance of bioactive peptides.

Bioavailability of milk protein-derived bioactive peptides: a glycaemic management perspective.

Milk protein-derived peptides have been reported to have potential benefits for reducing the risk of type 2 diabetes. However, what the active components are and whether intact peptides exert this bioactivity has received little investigation in human subjects. Furthermore, potentially useful bioactive peptides can be limited by low bioavailability. Various peptides have been identified in the gastrointestinal tract and bloodstream after milk-protein ingestion, providing valuable insights into their potential bioavailability. However, these studies are currently limited and the structure and sequence of milk peptides exerting bioactivity for glycaemic management has received little investigation in human subjects. The present article reviews the bioavailability of milk protein-derived peptides in human studies to date, and examines the evidence on milk proteins and glycaemic management, including potential mechanisms of action. Areas in need of advancement are identified. Only by establishing the bioavailability of milk protein-derived peptides, the active components and the mechanistic pathways involved can the benefits of milk proteins for the prevention or management of type 2 diabetes be fully realised in future.

Bioactive peptides released by in vitro digestion of standard and hydrolyzed infant formulas

Hydrolyzed infant formulas serve as appropriate nutritional sources for infants afflicted with cow’s milk allergy, and milk proteins in hydrolyzed formulas are industrially hydrolyzed extensively or partially. To investigate whether industrial hydrolysis may modulate the digestive trajectory of milk proteins, thereby releasing different profiles of bioactive peptides compared with standard formulas, both standard and hydrolyzed formulas were subjected to in vitro digestion and formation of bioactive peptides were compared. One standard, one extensively hydrolyzed, and one partially hydrolyzed infant formula were digested in vitro with pepsin and pancreatin, taking into account the higher gastric pH of infants, and the digesta were subjected to peptidomic analysis. The standard formula released a larger variety of bioactive peptides than from the hydrolyzed formulas, indicating that industrial hydrolysis of milk proteins may generally attenuate their indigenous bioactivities such as antibacterial, immuno-regulatory, and anti-oxidative activities. Conversely, industrial hydrolysis may facilitate the formation of bioactive peptides from hydrophobic proteins/regions such as β-LG and the “strategic zone” of β-CN, which encrypt bioactive peptides including a dipeptidyl dipeptidase-4-inhibitory, hypocholesterolemic, and opioid peptides. Infants fed hydrolyzed infant formulas may be influenced by milk protein-derived bioactive peptides in a manner different from those fed standard formula.

Bioactive peptides released from in vitro digestion of human milk with or without pasteurization.

Pasteurized donor human milk (HM) serves as the best alternative for breast-feeding when availability of mother's milk is limited. Pasteurization is also applied to mother's own milk for very low birth weight infants, who are vulnerable to microbial infection. Whether pasteurization affects protein digestibility and therefore modulates the profile of bioactive peptides released from HM proteins by gastrointestinal digestion, has not been examined to date. HM with and without pasteurization (62.5 °C for 30 min) were subjected to in vitro gastrointestinal digestion, followed by peptidomic analysis to compare the formation of bioactive peptides. Some of the bioactive peptides, such as caseinophosphopeptide homologues, a possible opioid peptide (or propeptide), and an antibacterial peptide, were present in undigested HM and showed resistance to in vitro digestion, suggesting that these peptides are likely to exert their bioactivities in the gastrointestinal lumen, or be stably transported to target organs. In vitro digestion of HM released a large variety of bioactive peptides such as angiotensin I-converting enzyme-inhibitory, antioxidative, and immunomodulatory peptides. Bioactive peptides were released largely in the same manner with and without pasteurization. Provision of pasteurized HM may be as beneficial as breast-feeding in terms of milk protein-derived bioactive peptides.

Milk-derived bioactive peptides: From science to applications

Milk proteins have received increasing attention as potential ingredients of health-promoting functional foods targeted at diet-related chronic diseases, such as cardiovascular disease, diabetes type two and obesity. To this end, growing interest has been focused on physiologically active peptides derived from milk proteins. These peptides are inactive within the sequence of the parent protein molecule and can be liberated by gastrointestinal digestion of milk, fermentation of milk with proteolytic starter cultures or hydrolysis by proteolytic enzymes. Milk protein-derived peptides have been shown under in vitro and in vivo conditions to exert a number of activities affecting the digestive, endocrine, cardiovascular, immune and nervous systems. A great variety of naturally formed bioactive peptides have been found in fermented dairy products, such as yoghurt, sour milk and cheese. Recently, industrial-scale technologies suitable for the industrial production of bioactive milk peptides have been developed. In addition, a few commercial food products supplemented with milk protein-derived bioactive peptides have been launched on limited markets. Some of these products carry clinically documented benefits, in particular for reduction of mild hypertension. The multifunctional properties of milk peptides appear to offer considerable potential for the development of many similar products in the near future.

Multifunctional peptides encrypted in milk proteins

Many bioactivities of milk are latent in that they are inactive within the protein sequence, requiring enzymatic proteolysis for release of bioactive peptides from milk proteins precursors. Bioactivities of peptides encrypted in major milk proteins are latent until released and activated, e.g. during gastrointestinal digestion or food processing. Bioactive peptides can be produced in vivo following intake of milk proteins, and the proteolytic system of bacterial species used in the production of fermented milk products and cheese can contribute to the liberation of bioactive peptides or precursors thereof. Activated peptides are potential modulators of various regulatory processes in the living system: immunomodulatory peptides stimulate the activities of cells of the immune system and several cytomodulatory peptides inhibit cancer cell growth, antimicrobial peptides kill sensitive microorganisms, angiotensin-I-converting enzyme (ACE)-inhibitory peptides exert an hypotensive effect, opioid peptides are opioid receptor ligands which can modulate absorption processes in the intestinal tract, mineral binding peptides may function as carriers for different minerals, especially calcium. Many milk-derived peptides reveal multifunctional properties, i.e. specific peptide sequences having two or more different biological activities have been reported. Milk protein-derived bioactive peptides are claimed to be health enhancing components that can be used to reduce the risk of disease or to enhance a certain physiological function.

Overview on Milk Protein-derived Peptides

Abstract Milk protein-derived bioactive peptides include a variety of substances which are potential modulators of various regulatory processes in the body; many peptides reveal multifunctional bioactivities. Opioid peptides are opioid receptor ligands with agonistic or antagonistic activities. Angiotensin converting enzyme (ACE)-inhibitory peptides can exert an antihypertensive effect. Immunomodulating casein peptides stimulate proliferation of human lymphocytes and phagocytic activities of macrophages. Antimicrobial peptides kill sensitive microorganisms. Antithrombotic peptides inhibit fibrinogen binding to a specific receptor region on the platelet surface and also inhibit aggregation of platelets. Caseinophosphopeptides can form soluble organophosphate salts and may function as carriers for different minerals, especially calcium. In relation to their mode of action, bioactive peptides may reach target sites (e.g., receptors and enzymes) at the luminal side of the intestinal tract or, after absorption, in peripheral organs. Milk-derived peptides can be produced on an industrial scale and as a consequence these peptides have already been considered for application both as dietary supplements in ‘functional foods’ and as drugs. Hence, these peptides are claimed to be health enhancing nutraceuticals for food and pharmaceutical preparations.