Identification of bioactive peptide from Oreochromis niloticus skin gelatin

Marine Bioactive Peptides: Anti-Photoaging Mechanisms and Potential Skin Protective Effects

Skin photoaging, resulting from prolonged exposure to ultraviolet radiation, is a form of exogenous aging that not only impacts the aesthetic aspect of the skin but also exhibits a strong correlation with the onset of skin cancer. Nonetheless, the safety profile of non-natural anti-photoaging medications and the underlying physiological alterations during the process of photoaging remain inadequately elucidated. Consequently, there exists a pressing necessity to devise more secure interventions involving anti-photoaging drugs. Multiple studies have demonstrated the noteworthy significance of marine biomolecules in addressing safety concerns related to anti-photoaging and safeguarding the skin. Notably, bioactive peptides have gained considerable attention in anti-photoaging research due to their capacity to mitigate the physiological alterations associated with photoaging, including oxidative stress; inflammatory response; the abnormal expression of matrix metalloproteinase, hyaluronidase, and elastase; and excessive melanin synthesis. This review provides a systematic description of the research progress on the anti-photoaging and skin protection mechanism of marine bioactive peptides. The focus is on the utilization of marine bioactive peptides as anti-photoaging agents, aiming to offer theoretical references for the development of novel anti-photoaging drugs and methodologies. Additionally, the future prospects of anti-aging drugs are discussed, providing an initial reference for further research in this field.

The current research status and strategies employed to modify food-derived bioactive peptides

The ability of bioactive peptides to exert biological functions has mainly contributed to their exploitation. The exploitation and utilization of these peptides have grown tremendously over the past two decades. Food-derived peptides from sources such as plant, animal, and marine proteins and their byproducts constitute a more significant portion of the naturally-occurring peptides that have been documented. Due to their high specificity and biocompatibility, these peptides serve as a suitable alternative to pharmacological drugs for treating non-communicable diseases (such as cardiovascular diseases, obesity, and cancer). They are helpful as food preservatives, ingredients in functional foods, and dietary supplements in the food sector. Despite their unique features, the application of these peptides in the clinical and food sector is to some extent hindered by their inherent drawbacks such as toxicity, bitterness, instability, and susceptibility to enzymatic degradation in the gastrointestinal tract. Several strategies have been employed to eliminate or reduce the disadvantages of peptides, thus enhancing the peptide bioactivity and broadening the opportunities for their applications. This review article focuses on the current research status of various bioactive peptides and the strategies that have been implemented to overcome their disadvantages. It will also highlight future perspectives regarding the possible improvements to be made for the development of bioactive peptides with practical uses and their commercialization.

Integration of Molecular Docking Analysis and Molecular Dynamics Simulations for Studying Food Proteins and Bioactive Peptides

In silico tools, such as molecular docking, are widely applied to study interactions and binding affinity of biological activity of proteins and peptides. However, restricted sampling of both ligand and receptor conformations and use of approximated scoring functions can produce results that do not correlate with actual experimental binding affinities. Molecular dynamics simulations (MDS) can provide valuable information in deciphering functional mechanisms of proteins/peptides and other biomolecules, overcoming the rigid sampling limitations in docking analysis. This review will discuss the information related to the traditional use of in silico models, such as molecular docking, and its application for studying food proteins and bioactive peptides, followed by an in-depth introduction to the theory of MDS and description of why these molecular simulation techniques are important in the theoretical prediction of structural and functional dynamics of food proteins and bioactive peptides. Applications, limitations, and future prospects of MDS will also be discussed.

Protective Effects of Small-Molecule Oligopeptides Isolated from Tilapia Fish Scale on Ethanol-Induced Gastroduodenal Injury in Rats

Peptic ulcer has a serious impact on people’s health around the world, and traditional medicines can cause adverse reactions. This study investigated the protective effects of tilapia collagen oligopeptides (TCOPs) on gastroduodenal injury. Seventy-two specific pathogen-free (SPF) male Sprague Dawley (SD) rats were randomly divided into six groups according to body weight: normal control group, ethanol group, whey protein group (500 mg/kg BW), and three TCOPs dose groups (250, 500, 1000 mg/kg BW). After intragastric administration for 30 days, the acute gastroduodenal injury was induced by anhydrous ethanol (5 mL/kg, intragastrically) in all groups except the normal control group. Biomarkers in gastric and duodenal tissue and serum were measured. Furthermore, western blot was used to detect the expression of apoptosis-related proteins. The results showed that the administration with TCOPs significantly reduced gastric and duodenal ulcer index, increased gastric juice pH, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities, along with the reduction of malondialdehyde (MDA) contents. TCOPs decreased tumor Necrosis Factor-α (TNF-α), interleukin-1β (IL-1β), and myeloperoxidase (MPO) levels, while interleukin– 10 (IL-10) levels were increased. Furthermore, pepsinogens 1 (PG1), pepsinogens 2 (PG2), gastrin (GAS), and the pepsinogen ratio (PGR) were decreased, the prostaglandin E2 (PGE2) and NO contents were increased after TCOPs intervention. Moreover, TCOPs up-regulated the expression of Bcl-2 and inhibited the expression of Bax and Caspase-3. In conclusion, TCOPs have protective effects on ethanol-induced gastroduodenal injury through gastrointestinal mucosal microcirculation promotion, antioxidation, anti-inflammation, and anti-apoptosis mechanisms.

Structure-function engineering of novel fish gelatin-derived multifunctional peptides using high-resolution peptidomics and bioinformatics

The multifunctional properties of fish gelatin hydrolysates have not been completely elucidated. Here, the biological characterization of these peptides was performed to engineer multifunctional peptides. Bioactive peptides were produced from mackerel byproducts via successive enzymatic hydrolysis reactions using subtilisin A and actinidin as microbial and herbal proteases. The antibacterial activity against both gram-negative and -positive food-borne pathogens, including Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Klebsiella pneumoniae, as well as the inhibitory potential of angiotensin-converting enzyme (ACE) and dipeptidyl peptidase IV (DPP-IV), was accessed in vitro. The synthesized peptides demonstrated multifunctional properties, which were further confirmed by in silico protocols. The ACE and DPP-IV inhibitory (IC₅₀) values of P1, P2, and P3 were 0.92 and 0.87, 0.51 and 0.93, 0.78 and 1.16 mg mL⁻¹, respectively. Moreover, the binding energy was sufficient for all three peptides to inhibit both ACE and DPP-IV enzymes with excellent three-dimensional conformation (RMSD = 0.000) for all six docking mechanisms.

Comparison of alcalase- and pepsin-treated oilseed protein hydrolysates - Experimental validation of predicted antioxidant, antihypertensive and antidiabetic properties

There is emerging evidence on the importance of food-derived bioactive peptides to promote human health. Compared with animal derived proteins, plant proteins, in particular oilseed proteins, are considered as affordable and sustainable sources of bioactive peptides. Based on our previous bioinformatic analysis, five oilseed proteins (flaxseed, rapeseed, sunflower, sesame and soybean) were enzymatically hydrolysed using alcalase and pepsin (pH 1.3 and pH 2.1). Further, low molecular weight (Mw ​< ​3 ​kDa) fractions were generated using ultrafiltration. The protein hydrolysates and their low Mw fractions were evaluated for their in vitro antioxidant, antihypertensive and antidiabetic capabilities, in comparison with samples obtained from two dairy proteins (whey and casein). Apart from dipeptidyl-peptidase IV inhibition, significantly stronger bioactivities were detected for the low Mw fractions. In partial agreement with in silico predictions, most oilseed hydrolysates exerted comparable angiotensin-converting enzyme inhibitory capability to dairy proteins, whilst whey protein was the most promising source of dipeptidyl-peptidase IV inhibitors. Apart from alcalase-treated soybean, dairy proteins were more efficient in releasing antioxidant peptides as compared to oilseed proteins. On the other hand, soybean protein hydrolysates showed the highest α-glucosidase inhibitory activity amongst all protein sources. Overall, there was limited correlation between in silico predictions and in vitro experimental results. Nevertheless, our results indicate that oilseed proteins have potential as bioactive peptide sources, and they might therefore be suitable replacers for dairy proteins as well as good sources for development of functional foods.

Fish Waste: From Problem to Valuable Resource

Following the growth of the global population and the subsequent rapid increase in urbanization and industrialization, the fisheries and aquaculture production has seen a massive increase driven mainly by the development of fishing technologies. Accordingly, a remarkable increase in the amount of fish waste has been produced around the world; it has been estimated that about two-thirds of the total amount of fish is discarded as waste, creating huge economic and environmental concerns. For this reason, the disposal and recycling of these wastes has become a key issue to be resolved. With the growing attention of the circular economy, the exploitation of underused or discarded marine material can represent a sustainable strategy for the realization of a circular bioeconomy, with the production of materials with high added value. In this study, we underline the enormous role that fish waste can have in the socio-economic sector. This review presents the different compounds with high commercial value obtained by fish byproducts, including collagen, enzymes, and bioactive peptides, and lists their possible applications in different fields.

Identification and characterization of novel antioxidant peptides from crucian carp (Carassius auratus) cooking juice released in simulated gastrointestinal digestion by UPLC-MS/MS and in silico analysis

The objective of this work was to separate, identify and assess antioxidant peptides from the simulated gastrointestinal (GI) digestion of crucian carp (Carassius auratus) cooking juice (CCCJ), which has been previously found with this activity. The CCCJ after simulated GI digestion treatment was separated gradually by ultrafiltration and RP-HPLC. Five novel antioxidant peptides with 10-13 amino acid residues were identified by UPLC-MS/MS. Their in silico assessments showed amphiphilic nature, good sensory quality and different target sites in the human body. Meanwhile, their three-dimensional structure predictions exhibited at least one β-turn, β-sheet and/or α-helix with partial hydrophobic and/or net-charged residues exposed to the external medium, which was good evidence for high antioxidant activity. Ultimately, four novel peptides with high antioxidant activity were found, among which IREADIDGDGQVN (1401 Da), PEILPDGDHD (1107 Da) and ASDEQDSVRL (1119 Da) exerted the highest DPPH radical scavenging activity with IC₅₀ of 1.78, 1.18 and 1.45 mM, respectively, while APLEEPSSPH (1063 Da) showed the highest Fe²⁺ chelating ability with IC₅₀ of 0.09 mM. This work could help understand the mechanism of CCCJ on human health promotion and improve the economic value of the crucian carp processing industry.

Preventive Effect of YGDEY from Tilapia Fish Skin Gelatin Hydrolysates against Alcohol-Induced Damage in HepG2 Cells through ROS-Mediated Signaling Pathways

According to a previous study, YGDEY from tilapia fish skin gelatin hydrolysates has strong free radical scavenging activity. In the present study, the protective effect of YGDEY against oxidative stress induced by ethanol in HepG2 cells was investigated. First, cells were incubated with YGDEY (10, 20, 50, and 100 μM) to assess cytotoxicity, and there was no significant change in cell viability. Next, it was established that YGDEY decreased the production of reactive oxygen species (ROS). Western blot results indicated that YGDEY increased the levels of superoxide dismutase (SOD) and glutathione (GSH) and decreased the expression of gamma-glutamyltransferase (GGT) in HepG2 cells. It was then revealed that YGDEY markedly reduced the expressions of bax and cleaved-caspase-3 (c-caspase-3); inhibited phosphorylation of Akt, IκB-α, p65, and p38; and increased the level of bcl-2. Moreover, the comet assay showed that YGDEY effectively decreased the amount of ethanol-induced DNA damage. Thus, YGDEY protected HepG2 cells from alcohol-induced injury by inhibiting oxidative stress, and this may be associated with the Akt/nuclear factor-κB (NF-κB)/mitogen-activated protein kinase (MAPK) signal transduction pathways. These results demonstrate that YGDEY from tilapia fish skin gelatin hydrolysates protects HepG2 cells from oxidative stress, making it a potential functional food ingredient.