Maria Hayes

Bioactive peptides from meat muscle and by-products: generation, functionality and application as functional ingredients.

Bioactive peptides are sequences of between 2-30 amino acids in length that impart a positive health effect to the consumer when ingested. They have been identified from a range of foods, including milk and muscle sources including beef, chicken, pork and marine muscles. The myriad of peptides identified from these sources have known antihypertensive, opioid, antioxidant, antithrombotic and other bioactivities. Indeed, bioactive peptides could play a role in the prevention of diseases associated with the development of metabolic syndrome and mental health diseases. The aim of this work is to present an overview of the bioactive peptides identified in muscle proteins and by-products generated during the processing of meat. The paper looks at the isolation, enrichment and characterisation strategies that have been employed to date to generate bioactive peptides and the potential future applications of these peptides in functional foods for the prevention of heart and mental health problems and obesity.

A review of antihypertensive and antioxidant activities in macroalgae.

Abstract There has been a significant increase in the occurrence of chronic diseases caused by oxidative stress and hypertension in recent decades. Hypertension is a sustained increase in blood pressure and is a controllable risk factor in the development of a number of cardiovascular diseases such as stroke and coronary infarction. As a result, the number of investigations aimed at identification of dietary compounds from natural sources that can be effective in preventing such diseases has increased. Macroalgae, also known as seaweeds or sea vegetables, have been traditionally incorporated into Pacific and Asian foods for hundreds of years and have recently become a popular addition to some Western diets. Macroalgae are classified into three higher taxa according to their pigmentation: brown (Class Phaeophyceae), green (Phylum Chlorophyta) and red (Phylum Rhodophyta). Owing to the harsh environments in which many macroalgae exist, they have developed effective defence mechanisms and, as a result, are a rich source of bioactive compounds, including polysaccharides, polyphenols, fatty acids and peptides, with different structures and activities from those found in terrestrial plants. This review explores the potential use of macroalgal species as bioactive ingredients that could be incorporated into functional foods for use in the prevention and/or treatment of hypertension and oxidative stress-related diseases.

Heart Health Peptides from Macroalgae and Their Potential Use in Functional Foods

Macroalgae have for centuries been consumed whole among the East Asian populations of China, Korea, and Japan. Due to the environment in which they grow, macroalgae produce unique and interesting biologically active compounds. Protein can account for up to 47% of the dry weight of macroalgae depending on species and time of cultivation and harvest. Peptides derived from marcoalgae are proven to have hypotensive effects in the human circulatory system. Hypertension is one of the major, yet controllable, risk factors in cardiovascular disease (CVD). CVD is the main cause of death in Europe, accounting for over 4.3 million deaths each year. In the United States it affects one in three individuals. Hypotensive peptides derived from marine and other sources have already been incorporated into functional foods such as beverages and soups. The purpose of this review is to highlight the potential of heart health peptides from macroalgae and to discuss the feasibility of expanding the variety of foods these peptides may be used in.

Isolation and Characterization of Bioactive Pro-Peptides with in Vitro Renin Inhibitory Activities from the Macroalga Palmaria palmata

Renin is the initial rate limiting step in the renin angiotensinogen system (RAS). To combat hypertension, various stages of the RAS can be positively affected. The aim of this study was to isolate and characterize renin inhibitory peptides from the red seaweed P. palmata for use in functional foods. Palmaria palmata protein was extracted and hydrolyzed with the food grade enzyme Papain to generate renin inhibitory peptides. Following proteolytic hydrolysis of P. palmata protein, reverse phase-high performance liquid chromatography (RP-HPLC) was employed to enrich for peptides with renin inhibitory activities. Fraction 25 (Fr-25) inhibited renin activities by 58.97% (±1.26) at a concentration of 1 mg/mL. This fraction was further characterized using nano-electrospray ionization quadropole/time-of-flight mass spectrometry (ESI-Q/TOF MS). A number of novel peptide sequences were elucidated, and the parent protein from which they were derived was determined using MS in tandem with protein database searches. All sequences were confirmed using de novo sequencing. The renin inhibitory peptide Ile-Arg-Leu-Ile-Ile-Val-Leu-Met-Pro-Ile-Leu-Met-Ala (IRLIIVLMPILMA) was chemically synthesized and its bioactivity confirmed using the renin inhibitory assay. Other stages of the RAS have recently been inhibited by bioactive peptides sourced from macroalgae, but this is the first study to isolate and characterize renin inhibitory peptides from the macroalgae.

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.

Identification of novel dipeptidyl peptidase-IV and angiotensin-I-converting enzyme inhibitory peptides from meat proteins using in silico analysis

Angiotensin-I-converting enzyme (ACE-I, EC 3.4.15.1), renin (EC 3.4.23.15), and dipeptidyl peptidase-IV (DPP-IV, EC 3.4.14.5) play key roles in the control of hypertension and the development of type-2 diabetes and other diseases associated with metabolic syndrome. The aim of this work was to utilize known in silico methodologies, peptide databases and software including ProtParam (http://web.expasy.org/protparam/), Basic Local Alignment Tool (BLAST), ExPASy PeptideCutter (http://web.expasy.org/peptide_cutter/) and BIOPEP (http://www.uwm.edu.pl/biochemia/index.php/pl/biopep) to assess the release of potentially bioactive DPP-IV, renin and ACE-I inhibitory peptides from bovine and porcine meat proteins including hemoglobin, collagen and serum albumin. These proteins were chosen as they are found commonly in meat by-products such as bone, blood and low-value meat cuts. In addition, the bioactivities of identified peptides were confirmed using chemical synthesis and in vitro bioassays. The concentration of peptide required to inhibit the activity of ACE-I and DPP-IV by 50% was determined for selected, active peptides. Novel ACE-I and DPP-IV inhibitory peptides were identified in this study using both in silico analysis and a literature search to streamline enzyme selection for peptide production. These novel peptides included the ACE-I inhibitory tri-peptide Ile-Ile-Tyr and the DPP-IV inhibitory tri-peptide Pro-Pro-Leu corresponding to sequences f (182-184) and f (326-328) of both porcine and bovine serum albumin which can be released following hydrolysis with the enzymes papain and pepsin, respectively. This work demonstrates that meat proteins are a suitable resource for the generation of bioactive peptides and further demonstrates the usefulness of in silico methodologies to streamline identification and generation of bioactive peptides.

Assessment of the angiotensin-I-converting enzyme (ACE-I) inhibitory and antioxidant activities of hydrolysates of bovine brisket sarcoplasmic proteins produced by papain and characterisation of associated bioactive peptidic fractions.

The main objective was to investigate the angiotensin-I-converting enzyme (ACE-I) inhibitory and antioxidant activities of sarcoplasmic proteins isolated from the brisket muscle (Pectoralis profundus) of 3 (Bos taurus) cattle and hydrolysed with papain for 24 h at 37°C. Sarcoplasmic protein hydrolysates were ultra-filtered using molecular weight cut off (MWCO) membranes and 10-kDa and 3-kDa filtrates were obtained. The total sarcoplasmic protein extracts and the 3-kDa filtrates were tested for angiotensin I-converting enzyme inhibitory (ACE-I) activities. The total hydrolysates, 10-kDa and 3-kDa filtrates were also tested for their associated antioxidant activities using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity assay, the ferric ion reducing antioxidant power (FRAP) assay and the Fe(2+) metal chelating ability assay. The peptidic content of the total hydrolysates, the 10-kDa and the 3-kDa filtrates were analysed using an ORBITRAP mass spectrometer, and mass spectral data obtained were analysed using TurboSEQUEST. Eleven peptides were characterised from the total hydrolysates, fifteen from the 10-kDa filtrate fractions, whilst nine peptides were characterised from the 3-kDa filtrate fractions. Similarities between the amino acid sequences of the peptides identified in this study and previously identified antioxidant and ACE-I inhibitory peptides detailed in the BIOPEP database were outlined.

Isolation, purification and characterization of antioxidant peptidic fractions from a bovine liver sarcoplasmic protein thermolysin hydrolyzate.

Sarcoplasmic proteins isolated from bovine livers were hydrolyzed using the enzyme thermolysin at 37°C for 2h. The hydrolyzates were filtered through molecular weight cut off membranes (MWCO) and filtrates were obtained. The water activity (a(w)) of unhydrolysed sarcoplasmic protein, full hydrolyzates, 10-kDa and 3-kDa filtrates were below the limit necessary for microbial growth. The antioxidant activities of both filtrates and fractions were assessed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity assay, the ferric ion reducing antioxidant power (FRAP) assay and the Fe(2+) chelating ability assay. RP-HPLC was used for purification of the full hydrolyzates, the 10-kDa and the 3-kDa filtrates. The peptidic content of the full hydrolyzates, the 10-kDa and the 3-kDa filtrates were assessed using the Dumas method and peptide contents of each fraction were characterized using electrospray quadrupole time-of-flight (ESI-Q-TOF) mass spectrometry with the resultant spectrum analysed using the software programmes Protein Lynx Global Server 2.4. and TurboSEQUEST. Similarities between the amino acid composition of characterized peptides from each fraction and previously reported antioxidant peptides were found. This study demonstrates that meat by-product such as liver can be utilised as raw material for the generation of bioactive peptides with demonstrated antioxidant activities in vitro using the enzyme thermolysin. It is significant as it presents a potential opportunity for meat processors to use their waste streams for the generation of bioactive peptides for potential functional food use.

Potential of a renin inhibitory peptide from the red seaweed Palmaria palmata as a functional food ingredient following confirmation and characterization of a hypotensive effect in spontaneously hypertensive rats.

This work examined the resistance of the renin inhibitory, tridecapeptide IRLIIVLMPILMA derived previously from a Palmaria palmata papain hydrolysate, during gastrointestinal (GI) transit. Following simulated GI digestion, breakdown products were identified using mass spectrometry analysis and the known renin and angiotensin I converting enzyme inhibitory dipeptide IR was identified. In vivo animal studies using spontaneously hypertensive rats (SHRs) were used to confirm the antihypertensive effects of both the tridecapeptide IRLIIVLMPILMA and the seaweed protein hydrolysate from which this peptide was isolated. After 24 h, the SHR group fed the P. palmata protein hydrolysate recorded a drop of 34 mm Hg in systolic blood pressure (SBP) from 187 (±0.25) to 153 (± 0.64) mm Hg SBP, while the group fed the tridecapeptide IRLIIVLMPLIMA presented a drop of 33 mm Hg in blood pressure from 187 (±0.95) to 154 (±0.94) mm Hg SBP compared to the SBP recorded at time zero. The results of this study indicate that the seaweed protein derived hydrolysate has potential for use as antihypertensive agents and that the tridecapeptide is cleaved and activated to the dipeptide IR when it travels through the GI tract. Both the hydrolysate and peptide reduced SHR blood pressure when administered orally over a 24 h period.

Algal Proteins: Extraction, Application, and Challenges Concerning Production

Population growth combined with increasingly limited resources of arable land and fresh water has resulted in a need for alternative protein sources. Macroalgae (seaweed) and microalgae are examples of under-exploited “crops”. Algae do not compete with traditional food crops for space and resources. This review details the characteristics of commonly consumed algae, as well as their potential for use as a protein source based on their protein quality, amino acid composition, and digestibility. Protein extraction methods applied to algae to date, including enzymatic hydrolysis, physical processes, and chemical extraction and novel methods such as ultrasound-assisted extraction, pulsed electric field, and microwave-assisted extraction are discussed. Moreover, existing protein enrichment methods used in the dairy industry and the potential of these methods to generate high value ingredients from algae, such as bioactive peptides and functional ingredients are discussed. Applications of algae in human nutrition, animal feed, and aquaculture are examined.