Angiotensin-I converting enzyme inhibitory peptides from antihypertensive skate (Okamejei kenojei) skin gelatin hydrolysate in spontaneously hypertensive rats

Peptide identification in a salmon gelatin hydrolysate with antihypertensive, dipeptidyl peptidase IV inhibitory and antioxidant activities

Salmon gelatin (Salmo salar, SG) enzymatic hydrolysates were generated using Alcalase 2.4L, Alcalase 2.4L in combination with Flavourzyme 500L, Corolase PP, Promod 144MG and Brewer's Clarex. The hydrolysate generated with Corolase PP for 1h (SG-C1) had the highest angiotensin converting enzyme (ACE, IC₅₀=0.13±0.05mgmL^-1) and dipeptidyl peptidase IV (DPP-IV, IC₅₀=0.08±0.01mgmL^-1) inhibitory activities, and oxygen radical absorbance capacity (ORAC, 540.94±9.57μmolTEg^-1d.w.). The in vitro bioactivities of SG-C1 were retained following simulated gastrointestinal digestion. Administration of SG and SG-C1 (50mgkg^-1 body weight) to spontaneously hypertensive rats (SHR) lowered heart rate along with systolic, diastolic and mean arterial blood pressure. The SG-C1 hydrolysate was fractionated using semi-preparative RP-HPLC and the fraction with highest overall in vitro bioactivity (fraction 25) was analysed by UPLC-MS/MS. Four peptide sequences (Gly-Gly-Pro-Ala-Gly-Pro-Ala-Val, Gly-Pro-Val-Ala, Pro-Pro and Gly-Phe) and two free amino acids (Arg and Tyr) were identified in this fraction. These peptides and free amino acids had potent ACE and DPP-IV inhibitory, and ORAC activities. The results show that SG hydrolysates have potential as multifunctional food ingredients particularly for the management of hypertension.

Bioactive Peptide of Marine Origin for the Prevention and Treatment of Non-Communicable Diseases

Non-communicable diseases (NCD) are the leading cause of death and disability worldwide. The four main leading causes of NCD are cardiovascular diseases, cancers, respiratory diseases and diabetes. Recognizing the devastating impact of NCD, novel prevention and treatment strategies are extensively sought. Marine organisms are considered as an important source of bioactive peptides that can exert biological functions to prevent and treatment of NCD. Recent pharmacological investigations reported cardio protective, anticancer, antioxidative, anti-diabetic, and anti-obesity effects of marine-derived bioactive peptides. Moreover, there is available evidence supporting the utilization of marine organisms and its bioactive peptides to alleviate NCD. Marine-derived bioactive peptides are alternative sources for synthetic ingredients that can contribute to a consumer's well-being, as a part of nutraceuticals and functional foods. This contribution focus on the bioactive peptides derived from marine organisms and elaborates its possible prevention and therapeutic roles in NCD.

Antihypertensive peptides from animal products, marine organisms, and plants

Bioactive peptides from food proteins exert beneficial effects on human health, such as angiotensin-converting enzyme (ACE) inhibition and antihypertensive activity. Several studies have reported that ACE-inhibitory peptides can come from animal products, marine organisms, and plants-derived by hydrolyzing enzymes such as pepsin, chymotrypsin, and trypsin-and microbial enzymes such as alcalase, thermolysin, flavourzyme, and proteinase K. Different ACE-inhibitory effects are closely related with different peptide sequences and molecular weights. Sequences of ACE-inhibitory peptides are composed of hydrophobic (proline) and aliphatic amino acids (isoleucine and leucine) at the N-terminus. As result of this review, we assume that low molecular weight peptides have a greater ACE inhibition because lower molecular weight peptides have a higher absorbency in the body. Therefore, the ACE-inhibitory effect is closely related with the degree of enzymatic hydrolysis and the composition of the peptide sequence.

STRUCTURAL CHARACTERISTICS AND ANTIHYPERTENSIVE EFFECTS OF ANGIOTENSIN-I-CONVERTING ENZYME INHIBITORY PEPTIDES IN THE RENIN-ANGIOTENSIN AND KALLIKREIN KININ SYSTEMS

BACKGROUND

The commercially available synthetic angiotensin-I-converting enzyme (ACE) inhibitors are known to exert negative side effects which have driven many research groups globally to discover the novel ACE inhibitors.

METHOD

Literature search was performed within the PubMed, ScienceDirect.com and Google Scholar.

RESULTS

The presence of proline at the C-terminal tripeptide of ACE inhibitor can competitively inhibit the ACE activity. The effects of other amino acids are less studied leading to difficulties in predicting potent peptide sequences. The broad specificity of the enzyme may be due to the dual active sites observed on the somatic ACE. The inhibitors may not necessarily competitively inhibit the enzyme which explains why some reported inhibitors do not have the common ACE inhibitor characteristics. Finally, the in vivo assay has to be carried out before the peptides as the antihypertensive agents can be claimed. The peptides must be absorbed into circulation without being degraded, which will affect their bioavailability and potency. Thus, peptides with strong in vitro IC50 values do not necessarily have the same effect in vivo and vice versa.

CONCLUSION

The relationship between peptide amino acid sequence and inhibitory activity, in vivo studies of the active peptides and bioavailability must be studied before the peptides as antihypertensive agents can be claimed.

Preclinical and Clinical Studies on Antioxidative, Antihypertensive and Cardioprotective Effect of Marine Proteins and Peptides-A Review

High seafood consumption has traditionally been linked to a reduced risk of cardiovascular diseases, mainly due to the lipid lowering effects of the long chained omega 3 fatty acids. However, fish and seafood are also excellent sources of good quality proteins and emerging documentation show that, upon digestion, these proteins are sources for bioactive peptides with documented favorable physiological effects such as antioxidative, antihypertensive and other cardioprotective effects. This documentation is mainly from in vitro studies, but also animal studies are arising. Evidence from human studies evaluating the positive health effects of marine proteins and peptides are scarce. In one study, a reduction in oxidative stress after intake of cod has been documented and a few human clinical trials have been performed evaluating the effect on blood pressure. The results are, however, inconclusive. The majority of the human clinical trials performed to investigate positive health effects of marine protein and lean fish intake, has focused on blood lipids. While some studies have documented a reduction in triglycerides after intake of lean fish, others have documented no effects.

ACE-Inhibitory and Antioxidant Activities of Peptide Fragments Obtained from Tomato Processing By-Products Fermented Using Bacillus subtilis: Effect of Amino Acid Composition and Peptides Molecular Mass Distribution

The effects of amino acid composition and peptide molecular mass on ACE-inhibitory and antioxidant activities of protein fragments obtained from tomato waste fermented using Bacillus subtilis were evaluated. The addition of B. subtilis increased the relative amounts of aromatic and positively-charged amino acids which have been described to influence the biological activities of peptide fragments. IC₅₀ values of hydrolysates for ACE-inhibitory and 2, 2'-diphenyl-1-picrylhydrazyl (DPPH) scavenging activities were found to be 1.5 and 8.2 mg/mL, respectively. Size-exclusion chromatography (SEC) pattern of the hydrolysate indicated the breakdown of parent proteins to smaller peptides with molecular weights mainly below 1400 Da. MALDI-TOF mass spectrometry analysis revealed that the highest ACE-inhibitory activity was due to peptides showing molecular mass range 500-800 Da, while the most active antioxidant peptides were found to be mainly at the two different peptide weight ranges 500-800 Da and 1200-1500 Da.

Hypolipidemic, antiobesity and cardioprotective effects of sardinelle meat flour and its hydrolysates in high-fat and fructose diet fed Wistar rats

AIMS

The present study aims to evaluate the antiobesity, hypolipidemic and cardioprotective effects of fermented sardinelle (Sardinella aurita) protein hydrolysates (FSPHs) produced with two proteolytic bacteria, Bacillus subtilis A26 (FSPH-A26) and Bacillus amyloliquefaciens An6 (FSPH-An6).

MAIN METHODS

Wistar rats were fed during 10weeks a standard laboratory diet, a high caloric diet (HCD) and a HCD coupled with the oral administration of sardinelle meat flour (SMF) or FSPHs.

KEY FINDINGS

HCD caused hyperlipidemia and increased body weight (BW). The daily oral administration of FSPHs or SMF reduced the total cholesterol (TC), triglycerides (TG) and low-density lipoprotein cholesterol (LDL-c) serum levels, and increased the level of high-density lipoprotein cholesterol (HDL-c). Nevertheless, FSPHs were found to be more efficient than SMF. FSPHs also lowered hepatic TC and TG content and decreased the pancreatic lipase activity. Further, the administration of FSPHs or SMF decreased the BW gain, the food intake and the relative epididymal adipose tissue weight. FSPHs exhibited a potent cardioprotective effect against heart attack, which was demonstrated by returning atherogenic indexes to their normal levels and the conservation of standard histological structure of the heart and aorta.

SIGNIFICANCE

The overall results indicate that FSPHs contained bioactive peptides which significantly attenuated hyperlipidemia, and might reduce the risk of cardiovascular disease (CVD) in rats fed HCD.

Biologically active peptides: Processes for their generation, purification and identification and applications as natural additives in the food and pharmaceutical industries

Recent technological advances have created great interest in the use of biologically active peptides. Bioactive peptides can be defined as specific portions of proteins with 2 to 20 amino acids that have desirable biological activities, including antioxidant, anti-hypertensive, antithrombotic, anti-adipogenic, antimicrobial and anti-inflammatory effects. Specific characteristics, including low toxicity and high specificity, make these molecules of particular interest to the food and pharmaceutical industries. This review focuses on the production of bioactive peptides, with special emphasis on fermentation and enzymatic hydrolysis. The combination of different technologies and the use of auxiliary processes are also addressed. A survey of isolation, purification and peptide characterization methods was conducted to identify the major techniques used to determine the structures of bioactive peptides. Finally, the antioxidant, antimicrobial, anti-hypertensive, anti-adipogenic activities and probiotic-bacterial growth-promoting aspects of various peptides are discussed.