Bioactive peptides from shrimp shell processing discards: Antioxidant and biological activities

Release principle of peptides and amino acids during the autolysis of shrimp head from Litopenaeus vannamei after UV-C irradiation stress

UV-C irradiation can activate endogenous enzymes in the body of many aquatic animals. Autolysis kinetics of shrimp head after UV-C irradiation stress was investigated. During the first 5 hr of autolysis, the release of the autolysis products was in line with the first-order equations of the reaction rate: Y = 37.681e-0.173 t , Pe = -1.769Y + 74.156, and TP = -1.5117Y + 60.866. A good linear correlation was founded between the release of total protein and that of products with molecular weight of 3,000 Da after these products associated with residual total protein were autolyzed. In contrast to the inconsistent effect of substrate concentration on autolysis rate constants, the effects of pH and temperature on the autolysis rate constants of shrimp head showed a consistent pattern. An Arrhenius equation (lnKa = 8,090.2/T - 26.497) was established to validate the proposed autolysis kinetic equations. The autolysis rate of products with molecular weight < 3,000 Da increased rapidly from 0 hr to 3 hr. The aliphatic amino acids showed a higher amount release than that of other amino acids during the autolysis. The amounts of released heterocyclic amino acids (Trp and His) were also much more than that of other amino acids.

Isolation of Novel ACE-Inhibitory and Antioxidant Peptides from Quinoa Bran Albumin Assisted with an In Silico Approach: Characterization, In Vivo Antihypertension, and Molecular Docking

Albumin is the major fraction of quinoa protein that is characterized as having high nutritional value. However, until now, scant information is available on the bioactivity of quinoa albumin or its hydrolysates. To promote its usage, we extracted albumin in this study from quinoa bran assisted with cellulase and hemicellulose, and hydrolyzed it by alcalase and trypsin to produce bioactive peptides. The hydrolysates (QBAH) were purified by gel filtration and reversed-phase high-performance liquid chromatography (RP-HPLC), followed by identification using liquid chromatography–mass spectrometry (LC-MS/MS). Furthermore, based on in silico analysis, one angiotensin-I converting enzyme (ACE)-inhibitory and antioxidant peptide, RGQVIYVL (946.6 Da), and two antioxidant peptides, ASPKPSSA (743.8 Da), and QFLLAGR (803.5 Da), from QBAH were synthesized. RGQVIYVL showed a high ACE-inhibitory activity (IC₅₀ = 38.16 μM) with competitive mode of inhibition, and showed significant antihypertensive effect in spontaneously hypertensive rats at a concentration of 100–150 mg/kg body weight (bw). Molecular docking simulation showed that it could interact with the active ACE site via hydrogen bonds with high binding power. Moreover, RGQVIYVL, ASPKPSSA, and QFLLAGR all demonstrated high ·OH scavenging activity (IC₅₀ = 61.69–117.46 μM), ABTS⁺ scavenging activity (58.29–74.28%) and Fe²⁺ chelating ability (32.54–82.48% at 0.5 mg/mL). They could also retain activity after gastrointestinal enzyme digestion. These results indicate that quinoa albumin is a potential source of bioactive peptides possessing antioxidant and ACE-inhibitory activities.

Effect of extrusion on physicochemical properties, functional properties and antioxidant activities of shrimp shell wastes protein

Different conditions of extrusion variables (temperature and moisture content) were applied to shrimp shell wastes (SSW), and its effects on the physicochemical, functional properties and antioxidant activities of shrimp shell wastes protein (SSWP) were investigated. The results showed that extrusion caused marked improvements in the protein content and yields compared with the control, and it resulted in the changes of SSWP on the amino acids composition, functional properties, thermal properties and morphological properties. The protein from extruded SSW showed better antioxidant activities than the untreated one. When the six samples were compared by principal component analysis, the protein obtained at the conditions of 25% moisture content at 150 °C (T3M2) were observed to have the highest comprehensive principal component values. The results provided a better choice for SSW in extrusion processing, which would be helpful for the SSWP related products in the food industry.

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.

Hydrolyzed collagen from porcine lipase-defatted seabass skin: Antioxidant, fibroblast cell proliferation, and collagen production activities

Defatting of seabass skins using porcine pancreas lipase (PPL) at 25 or 50 units/g dry matter) for 1-3 hr at 30ºC was investigated. Treatment of seabass skin with PPL (25 unit/g dry matter) for 3 hr removed 83.81% lipids when compared to 57.27% using isopropanol. Hydrolysis of PPL-treated skin by papain (0.3 unit/g dry matter) (PPL-papain-3 process) at 40ºC for 90 min provided hydrolyzed collagen (HC) with higher yield, α-amino group content, ferric-reducing antioxidant power, and metal chelating activity than other treatments (p < 0.05). There was no difference in fishy odor between HC from PPL-papain-2 and PPL-papain-3 processes (p > 0.05). All the HC (50-250 µg/ml) samples stimulated L929 fibroblast cell proliferation and also induced collagen production in a dose-dependent manner. Also, all HC contained peptides with molecular weight of 406-11,860 Da. Gly and imino acids were dominant amino acids in HC prepared with PPL-papain-3 process. PRACTICAL APPLICATIONS: Seabass skin is a potential raw material for the production of hydrolyzed collagen (HC). However, seabass skin contains a large amount of lipids, including polyunsaturated fatty acids. These unsaturated lipids are oxidized during processing, particularly during hydrolysis at high temperature. This leads to the development of undesirable odor, especially fishy odor. Therefore, seabass skin defatting is an important step for improving the quality of the resulting HC. The use of lipase is an alternative method that can be used to remove lipids in skins without using solvents. HC from defatted skins will contain bioactive peptides and therefore, can be used as a food supplement or for skin nourishment.

Antihypertensive and anticoagulant properties of glycosaminoglycans extracted from the sturgeon (Acipenser persicus) cartilage

Large amounts of valuable waste are produced during sea food processing. This has a great potential for conversion to biologically active proteins and polysaccharides. Among these compounds, sulfated polysaccharides have been considered due to their many biological properties.

The present work was conducted to study anticoagulant activities and angiotensin-I converting enzyme (ACE) inhibitory effects of glycosaminoglycans (GAGs) extracted from the cartilage of sturgeon (Acipenser persicus). The enzymatic extraction of sturgeon cartilage was performed in the presence of cetylpyridinium chloride salt. The structure was characterized via electron microscope and Fourier transform infrared spectroscopy (FTIR) analysis. Herein, ACE inhibitory and anticoagulant properties of extracted GAGs were determined.

The amount of GAGs was 6.8±1.3% of cartilage dry weight. GAGs showed good activity in ACE inhibitory – with a highest level of 85.7%. The derived anticoagulant activity indexes, APPT (activated partial thromboplastin time) and TT (Thrombin time) of the extracted polysaccharide showed a prolonging of clotting time, compare to control.

The results of this study revealed that the cartilage extracted GAGs possess promising ACE inhibitory properties and anticoagulant effects. Thus, the product can be substituted for blood reducing drugs and antithrombotic agents at least in laboratory conditions.

Whole-grain oats (Avena sativa L.) as a carrier of lactic acid bacteria and a supplement rich in angiotensin I-converting enzyme inhibitory peptides through solid-state fermentation

This study explored a novel strategy to develop solid-state whole-grain oats as a novel carrier of lactic acid bacteria and a nutraceutical supplement rich in ACE inhibitory peptides. Oats were fermented by Lactobacillus plantarum B1-6, Rhizopus oryzae, or a combination of L. plantarum B1-6 and R. oryzae. L. plantarum showed a much better growth performance in oats when it was combined with R. oryzae than when it was cultured alone, as evidenced by an increase in viable cell count to 9.70 log cfu g-1 after 72 h of fermentation. The coinoculated fermented oats (CFO) and the R. oryzae-fermented oats (RFO) were then selected for investigations on protein hydrolysis and on the functional properties of the released bioactive peptides. The results showed that the soluble protein contents changed from 7.05 mg g-1 to 14.43 and 10.21 mg g-1 for CFO and RFO, respectively. However, the degree of hydrolysis and the content of peptides with molecular masses less than 10 000 Da indicated that the CFO proteins can be degraded to a greater degree. As analyzed by electrophoresis and reversed-phase high-performance liquid chromatography, the protein and peptide profiles of CFO and RFO demonstrated that the proteins from CFO were more obviously hydrolyzed and more small peptides were obtained. In addition, both CFO and RFO presented higher ACE inhibitory activities than unfermented oats, whereas the protein extracts from CFO exerted a lower IC50 value of 0.42 mg protein per mL compared with the protein extracts from the other samples. This research has broadened our knowledge on the development of whole-grain oat products as a probiotic carrier and on the difference between mixed solid-state fermentation (SSF) and fungi SSF in terms of protein degradation and the capacity to release ACE inhibitory peptides. Our approach could be used to obtain probiotic food products and probably to develop oats as a potential therapeutic ingredient targeting hypertension.

Isolation and Evaluation of Bioactive Protein and Peptide from Domestic Animals' Bone Marrow

In this work, proteins and peptides were isolated from four kinds of animal bone marrow and characterized by sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and liquid chromatography-mass spectrometry (LC/MS). The antimicrobial and antioxidant activity of these proteins were investigated in vitro. The nutritional value was evaluated by analyzing their free amino acid composition. The results indicates that all of the extracts appeared two bands at SDS-PAGE, the peptide band at 4.1⁻10 kDa and protein band at 66 kDa, these data are consistent with LC/MS results. FT-IR analysis showed that the secondary structure of protein mainly consists of α-helix. SEM micrographs revealed that the fractions have different morphological characteristics. Horse bone marrow protein (HBMP) showed the highest antioxidant activity to DPPH free radical, IC₅₀ value was 0.573 mg/mL. Most of the obtained fractions showed antimicrobial activities towards Escherichiacoli (EC) and Candida albicans (CA). Total free amino acid content ranged between 5.15⁻49.60 mg/g, and among them, HBMP displayed the highest abundance, 49.7 mg/g, which amino acid composition ratio approached the Food and Agriculture Organization/World Health Organization (FAO/WHO) ideal amino acid pattern recommendation. This study provides fundamental knowledge and a basic study method for the research into and development of animal bone marrow proteins and peptides as functional food and drug resources.

Bioinformatics and peptidomics approaches to the discovery and analysis of food-derived bioactive peptides

There are emerging advancements in the strategies used for the discovery and development of food-derived bioactive peptides because of their multiple food and health applications. Bioinformatics and peptidomics are two computational and analytical techniques that have the potential to speed up the development of bioactive peptides from bench to market. Structure-activity relationships observed in peptides form the basis for bioinformatics and in silico prediction of bioactive sequences encrypted in food proteins. Peptidomics, on the other hand, relies on "hyphenated" (liquid chromatography-mass spectrometry-based) techniques for the detection, profiling, and quantitation of peptides. Together, bioinformatics and peptidomics approaches provide a low-cost and effective means of predicting, profiling, and screening bioactive protein hydrolysates and peptides from food. This article discuses the basis, strengths, and limitations of bioinformatics and peptidomics approaches currently used for the discovery and analysis of food-derived bioactive peptides.

Intracellular antioxidant effect of vanillin, 4-methylguaiacol and 4-ethylguaiacol: three components in Chinese Baijiu

Vanillin, 4-methylguaiacol, and 4-ethylguaiacol can improve AAPH-induced alterations in oxidative stress biomarkers and antioxidant enzymes in HepG2 cells.