Angiotensin-I converting enzyme inhibitory and antioxidant activity of bioactive peptides produced by enzymatic hydrolysis of skin from grass carp (Ctenopharyngodon idella)

Novel Peptide Sequences with ACE-Inhibitory and Antioxidant Activities Derived from the Heads and Bones of Hybrid Groupers (Epinephelus lanceolatus × Epinephelus fuscoguttatus)

The heads and bones of hybrid groupers are potential precursors for angiotensin-converting enzyme (ACE)-inhibitory and antioxidant peptides. The aim of this study was to isolate the dual-action peptides from the Alcalase-treated head and bone hydrolysate of hybrid groupers followed by identification of the novel peptides. The stability of these peptides against stimulated in vitro gastrointestinal digestion (SGID) was also determined. Fraction HB-IV (less than 1 kDa) obtained from ultrafiltration showed the strongest ACE-inhibition ability (IC50: 0.28 mg/mL), which was comparable to the potency of the commercial supplement, PeptACE (IC50: 0.22 mg/mL). This fraction also demonstrated the highest hydroxyl radical scavenging and metal-chelating activities. However, further fractionation of HB-IV by a series of chromatography resulted in peptide fractions of reduced ACE-inhibitory and antioxidant activities. The hydroxyl radical scavenging and reduction potential of HB-IV were enhanced, whereas ACE-inhibitory and metal-chelating activities were reduced following SGID. A total of 145 peptide sequences were identified from HB-IV, of which 137 peptides were novel to the BIOPEP database. The results suggested that the bioactive peptides isolated from the heads and bones of hybrid groupers could be used as functional foods/ingredients with potential ACE-inhibitory and antioxidant effects.

Extraction optimization and screening of antioxidant peptides from grass carp meat and synergistic-antagonistic effect

Grass carp (Ctenopharyngodon idellus) is one of the three most cultivated freshwater fish around the world, but it is mainly consumed afresh, so only a small part of them are processed into salted fish or snack food. This research was performed to prepare and screen antioxidant peptides from grass carp muscle to promote its high‐value utilization. The parameters of double‐enzyme two‐step hydrolysis were optimized, the peptides with the highest ABTS.⁺ scavenging ability were enriched and identified by Sephadex G‐25 and LC‐Q‐Orbitrap‐MS/MS. The synergistic–antagonistic effect among identified peptides was also investigated. The optimized conditions were hydrolyzed with protamex (10,000 U/g) at pH 8.0, 50°C for 3 h, followed by hydrolysis with alcalase (6,000 U/g) at pH 9.0, 50 °C for 2 h, and the protein–liquid ratio was 4%. The hydrolysates were further fractionated to obtain five fractions, in which fraction 3 (F3) exhibited the strongest ABTS.⁺ and O2·‐ scavenging ability with the IC₅₀ values of 0.11 and 0.47 mg/ml, respectively. Twelve novel antioxidant peptides were identified, in which VAGW possessed the highest activity (139.77 μmol GSH/g). Significantly synergistic effects were observed on the two and three peptides’ combination among VAGW, APPAMW, LFGY, FYYGK, and LLLYK, while the C‐terminal tryptophan (Trp) played an important role in the synergism. This study found that grass carp muscle hydrolysates can be potential natural antioxidants in functional products. The synergistic effects among peptides may provide a perspective for the combined application of peptides.

Effect of Fish Bone Bioactive Peptides on Oxidative, Inflammatory and Pigmentation Processes Triggered by UVB Irradiation in Skin Cells

In the present study, we evaluated for the first time the photoprotective effect of fish bone bioactive peptides (FBBP) preparation isolated from silver carp (Hypophthalmichthys molitrix) discarded tissue using in vitro experimental models of skin cells exposed to ultraviolet B (UVB) irradiation and stressing agents. FBBP preparation was obtained by papain treatment of minced bones and centrifugal ultrafiltration, and the molecular weight (MW) distribution was characterized by size exclusion and reversed-phase high performance liquid chromatography (RP-HPLC). In vitro assessment of the effect of FBBP pretreatment in UVB-irradiated L929 fibroblasts and HaCaT keratinocytes revealed their cytoprotective activity. Their capacity to efficiently reduce reactive oxygen species (ROS) production and lipid peroxidation varied in a dose-dependent manner, and it was greater in fibroblasts. A decrease of proinflammatory cytokines secretion, in particular of tumor necrosis factor alpha (TNF-α), was found after FBBP pretreatment of THP-1-derived inflamed macrophages. Melanin production and tyrosinase activity investigated in UVB-irradiated Mel-Juso cells were lowered in direct relation to FBBP concentrations. FBBP fractions with high radical scavenging activity were separated by ion exchange chromatography, and two collagenic sequences were identified. All these results offer new scientific data on aquaculture fish bone-derived peptides confirming their ability to control the antioxidant, anti-inflammatory and pigmentation processes developed during UV irradiation of skin cells and recommend their use as valuable natural ingredients of photoprotective cosmeceutical products.

Recently isolated food-derived antihypertensive hydrolysates and peptides: A review

Hypertension is a non-communicable disease characterized by elevated blood pressure, and a prominent metabolic syndrome of modern age. Food-borne bioactive peptides have shown considerable potencies as suitable therapeutic agents for hypertension. The peptide inhibition of the angiotensin I-converting enzyme (ACE) from its default biochemical conversion of Ang I to Ang II has been studied and more relatively adopted in several studies. This review offers an examination of the isolation of concomitant proteins in foods, their hydrolysis into peptides and the biofunctionality checks of those peptides based on their anti-hypertensive potentialities. Furthermore, critical but concise details about methodologies and analytical techniques used in the purification of such peptides are discussed. This review is a beneficial literature supplement for scholars and provides functional awareness material for the food-aligned alternative therapy for hypertension. In addition, it points researchers in the direction of adopting food materials and associated by-products as natural sources for the isolation biologically active peptides.

Use of Alcalase in the production of bioactive peptides: A review

This review aims to cover the uses of the commercially available protease Alcalase in the production of biologically active peptides since 2010. Immobilization of Alcalase has also been reviewed, as immobilization of the enzyme may improve the final reaction design enabling the use of more drastic conditions and the reuse of the biocatalyst. That way, this review presents the production, via Alcalase hydrolysis of different proteins, of peptides with antioxidant, angiotensin I-converting enzyme inhibitory, metal binding, antidiabetic, anti-inflammatory and antimicrobial activities (among other bioactivities) and peptides that improve the functional, sensory and nutritional properties of foods. Alcalase has proved to be among the most efficient proteases for this goal, using different protein sources, being especially interesting the use of the protein residues from food industry as feedstock, as this also solves nature pollution problems. Very interestingly, the bioactivities of the protein hydrolysates further improved when Alcalase is used in a combined way with other proteases both in a sequential way or in a simultaneous hydrolysis (something that could be related to the concept of combi-enzymes), as the combination of proteases with different selectivities and specificities enable the production of a larger amount of peptides and of a smaller size.

Shelf-life extension of whole shrimp using an active coating containing fish skin gelatin hydrolysates produced by a natural protease

This study was focused on shelf-life extension of whole shrimp (Penaeus merguiensis) using an active coating containing gelatin hydrolysates. Gelatin extracted from Scomberomorus commerson skin was hydrolyzed using actinidin extracted from kiwifruit. Some important physicochemical characteristics of fish skin gelatin including viscosity, gelling and melting points, and temperatures were examined. The whole shrimp was coated with four coating agents including fish skin gelatin (FG), commercial gelatin (CG), fish skin gelatin containing 1 mg/ml fish gelatin hydrolysates (FG + GH), and commercial bovine gelatin containing 1 mg/ml fish gelatin hydrolysates (CG + GH). Chemical, microbial, and sensorial properties of samples were monitored for 12 days at 4°C with 3-day intervals (0-12 days). The pH value of samples coated with FG + GH and CG + GH showed the lowest changes during 12 days of storage (1.68 ± 0.00 and 1.70 ± 0.09, respectively). The free fatty acid content (FFA), total volatile base nitrogen (TVB-N), lipid oxidation, and carbonyl content of samples coated with FG + GH and CG + GH were significantly lower than that of control, CG, and FG samples. The results of this study showed that the gelatin hydrolysates could be used as a preservative costing agent for whole shrimp.

Aquaculture and by-products: Challenges and opportunities in the use of alternative protein sources and bioactive compounds

There is a growing concern about chronic diseases such as obesity, diabetes, hypertension, hypercholesterolemia, cancer and cardiovascular diseases resulting from profound changes in the western lifestyle. Aquaculture by-products are generated in large quantities and they can be profitably recycled through their bioactive compounds used for health or food supplements. Improving waste utilization in the field of aquaculture is essential for a sustainable industry to prevent or minimize the environmental impact. In this sense fish by-products are a great source of protein and omega-3 polyunsaturated fatty acids which are particularly studied on Atlantic salmon or rainbow trout. Fish protein hydrolysate (FPH) obtained from chemical, enzymatical and microbial hydrolysis of processing by-products are being used as a source of amino acids and peptides with high digestibility, fast absorption and important biological activities. Omega-3 polyunsaturated fatty acids, eicosapentaenoic (EPA) and docosahexaenoic (DHA) from fish discards have been reported to decrease postprandial triacylglycerol levels, reduction of blood pressure, platelet aggregation and the inflammatory response. Crustacean by-products can also be used to produce chitosan with antioxidant and antimicrobial activity for food and pharmaceutical industries and carotenoids with important biological activity. Seaweeds are rich in bioactive compounds such as alginate, carrageenan, agar, carotenoids and polyphenols with different biological activities such as antioxidant, anticancer, antidiabetic, antimicrobial or anti-inflammatory activity. Finally, regarding harvest microalgae, during the past decades, they were mainly used in the healthy food market, with >75% of the annual microalgal biomass production, used for the manufacture of powders, tablets, capsules or pills. We will report and discuss the present and future role of aquaculture by-products as sources of biomolecules for the design and development of functional foods/beverages. This chapter will focus on the main bioactive compounds from aquaculture by-products as functional compounds in food and their applications in biomedicine for the prevention and treatment of diseases.

Identification and inhibitory activity against α-thrombin of a novel anticoagulant peptide derived from oyster (Crassostrea gigas) protein

A newly discovered anticoagulant peptide was isolated, purified and identified from the pepsin hydrolysate of oyster (Crassostrea gigas) which could potently prolong the activated partial thromboplastin time and the thrombin time. The anticoagulant peptide with a 1264.36 Da molecular mass was similar to the amino acid sequence of the C-terminal segment (DFEEIPEEYLQ) of hirudin (a potent thrombin inhibitor). The peptide specifically inhibited a vital blood coagulation factor: thrombin. The molecular docking energy scores of the anticoagulant peptide with the active site, exosite-I and exosite-II of thrombin were 132.355 kcal mol-1, 151.266 kcal mol-1 and 147.317 kcal mol-1, respectively. The anticoagulant peptide interacted with thrombin by competing with fibrinogen for an anion-binding exosite I. In the anticoagulant peptide-thrombin complex, there are seven hydrogen bonds and reciprocity exists between hydrogen atoms and oxygen atoms, and electrostatic and hydrophobic interactions are also involved. Such abundant interactions may be accountable for the high affinity and specificity of the anticoagulant peptide.

Antihypertensive activity of fish protein hydrolysates and its peptides

The rising interest to utilize nutritionally exorbitant fish proteins has instigated research activities in fish waste utilization. The development of newer technologies to utilize fish waste has fostered use of bioactive value-added products for specific health benefits. Enzymatically obtained Fish Protein Hydrolysate (FPH) is a rich source of biologically active peptides possessing anti-oxidant, anticancer, antimicrobial and anti-hypertensive activity. Isolating natural remedies to combat alarming negative consequences of synthetic drugs has been the new trend in current research promoting identification of antihypertensive peptides from FPH. In this review, we aim to culminate data available to produce antihypertensive peptides from FPH, its composition and potential to be used as a therapeutic agent. These purified peptides are known to be rich in arginine, valine and leucine. Reports reveal peptides with low molecular weight (<1 kDa) and shorter chain length (<20 amino acids) exhibited higher antihypertensive activity. As these peptides have proven Angiotensin Converting Enzyme - I inhibitory activity in vitro and in vivo, their potential to be used as antihypertensive drugs is outrageous. However, current focus on research in the field of molecular docking is necessary to have improved understanding of interaction of the peptides with the enzyme.