Peptide isolated from Japanese flounder skin gelatin protects against cellular oxidative damage

Antioxidant Marine Hydrolysates Isolated from Tuna Mixed Byproducts: An Example of Fishery Side Streams Upcycling

The aim of this research is to propose simple and scalable processes to obtain bioactive peptides extensively hydrolyzed starting from a tuna mixed biomass. The upcycling of this powdered biomass is challenging since it comes from the unsorted industrial side streams of the tuna canning process (cooked residues from fillet trimming) after a patented mild dehydration useful for preventing its degradation until its exploitation. Two different protocols were proposed, with and without the inclusion of an exogenous enzyme (Enzymatic-Assisted Extraction, EAE), with no relevant differences in yields (24% vs. 22%) and a comparable amino acid composition. Nevertheless, the former protocol (with EAE) provided peptides with an average molecular weight of 1.3 kDa, and the second one (without EAE) provided peptides with an average molecular weight of 2.2 kDa. The two corresponding types of tuna protein hydrolysates (Enzymatic Hydrolysates (EH) and Non-Enzymatic Hydrolysates (NEH)) were characterized by proximate compositions, pH, color profile, amino acid analysis, FTIR spectra, and molecular weight distribution. In addition, several biological analyses were performed to assess their potential use as nutraceutical supplements: special attention has been paid to antioxidant activity using three different methods to quantify it. EH showed the most promising antioxidant activity which could be exploited also in other fields (e.g., biomaterials, cosmetics).

Isolation, purification, and antiosteoporosis activity of donkey bone collagen from discarded bone and its antioxidant peptides

Oxidative stress plays a crucial role in the development of osteoporosis. In this study, it was observed that donkey bone collagen (DC) at a concentration of 500 μg/mL scavenged 17.89 % of 1,1-Diphenyl-2-picrylhydrazyl (DPPH) free radicals, indicating its antioxidant properties. Additionally, when an oxidative damage osteoblast model was created using H2O2, 100 μg/mL DC demonstrated the ability to enhance cell survival by 27.31 %. Furthermore, 50 μg/mL DC increased the intracellular differentiation marker alkaline phosphatase (ALP) level by 62.65 %. Additionally, the study revealed that DC significantly increased the expression of osteoporosis-related factors in serum and effectively restored the abnormal structure of spongy bone in mice osteoporosis model. Peptides (GGWFL, ANLGPA, and GWFK) isolated from DC through gastrointestinal digestion and subsequent enzymatic purification in vitro demonstrated the ability to safeguard osteoblasts from H2O2-induced damage by reducing intracellular reactive oxygen species (ROS). This protection resulted in enhanced cell survival and promoted osteoblast differentiation. This investigation underscores that DC can shield oxidative damage osteoblast model from oxidative stress, ameliorate osteoporosis, and enhance bone density in mice osteoporosis model. These findings suggest various DC applications in the food and medicine industries.

The Peptide Fractions of Cheddar Cheese Made with Lactobacillus helveticus 1.0612 Play Protective Effects in H2O2-Induced Oxidative-Damaged Caco-2 Cells Models

In this study, water-soluble peptide (WSP) fractions of cheddar cheese made with Lactobacillus helveticus 1.0612 were purified into WSP-Ⅰ (<3 kDa), WSP-Ⅱ (3-10 kDa), and WSP-Ⅲ (>10 kDa). The protective effects of WSP, WSP-Ⅰ, WSP-Ⅱ, and WSP-Ⅲ fractions against oxidative stress in Caco-2 cells were assayed, and the cytoprotective mechanism of WSP-Ⅰ on cells oxidative damage was elucidated via metabolomics. The results showed that all four peptide fractions were able to attenuate the decrease in cell viability caused by oxidative stress and also could reduce the production of reactive oxygen species and malondialdehyde caused by oxidative stress, and increased cellular catalase and superoxide dismutase activities, thereby enhancing cellular antioxidant capacity. The WSP-Ⅰ fraction with the highest protective effect was used for metabolomics analysis, and 15 significantly different metabolites were screened. Functional pathway analysis revealed that the protective effect of the WSP-I fraction was related with nine metabolic pathways and weakened the metabolic disorders caused by H₂O₂ via regulating energy metabolism and amino acid metabolism. All in all, peptide fractions of cheddar cheese showed a cytoprotective effect through improved cellular metabolism.

Isolation, structures and biological activities of medicinal glycoproteins from natural resources: A review

In recent years, natural resources have proven to be tremendous sources of glycoproteins. As biological macromolecules, glycoproteins are essential to the growth and development of organisms, and have attracted increasing attention around the world. This review summarized and discussed the development of glycoproteins from natural resources, including isolation methods, purification processes, structural features and biological activities. Generally, the vast majority of glycoproteins can be isolated by hot water extraction followed by purification through gel filtration chromatography. Combined with component analysis, the physicochemical properties of glycoproteins are studied by using several spectroscopic techniques such as ultraviolet-visible (UV-Visible), Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR). Moreover, natural glycoproteins possess various remarkable biological activities, including anti-tumor, anti-oxidant, anti-coagulant and anti-microbial activities. The content of this review will provide a theoretical basis for the research on related glycoproteins and give a perspective on the use of these medical resources.

An Analysis of the Plant- and Animal-Based Hydrocolloids as Byproducts of the Food Industry

Hydrocolloids are naturally occurring polysaccharides or proteins, which are used to gelatinize, modify texture, and thicken food products, and are also utilized in edible films and drug capsule production. Moreover, several hydrocolloids are known to have a positive impact on human health, including prebiotics rich in bioactive compounds. In this paper, plant-derived hydrocolloids from arrowroot (Maranta arundinacea), kuzu (Pueraria montana var lobata), Sassafras tree (Sassafras albidum) leaves, sugarcane, acorn, and animal-derived gelatin have been reviewed. Hydrocolloid processing, utilization, physicochemical activities, composition, and health benefits have been described. The food industry generates waste such as plant parts, fibers, residue, scales, bones, fins, feathers, or skin, which are often discarded back into the environment, polluting it or into landfills, where they provide no use and generate transport and storage costs. Food industry waste frequently contains useful compounds, which can yield additional income if acquired, thus decreasing the environmental pollution. Despite conventional manufacturing, the aforementioned hydrocolloids can be recycled as byproducts, which not only minimizes waste, lowers transportation and storage expenses, and boosts revenue, but also enables the production of novel, functional, and healthy food additives for the food industry worldwide.

Potential Cosmetic Active Ingredients Derived from Marine By-Products

The market demand for marine-based cosmetics has shown a tremendous growth rate in the last decade. Marine resources represent a promising source of novel bioactive compounds for new cosmetic ingredient development. However, concern about sustainability also becomes an issue that should be considered in developing cosmetic ingredients. The fisheries industry (e.g., fishing, farming, and processing) generates large amounts of leftovers containing valuable substances, which are potent sources of cosmeceutical ingredients. Several bioactive substances could be extracted from the marine by-product that can be utilized as a potent ingredient to develop cosmetics products. Those bioactive substances (e.g., collagen from fish waste and chitin from crustacean waste) could be utilized as anti-photoaging, anti-wrinkle, skin barrier, and hair care products. From this perspective, this review aims to approach the potential active ingredients derived from marine by-products for cosmetics and discuss the possible activity of those active ingredients in promoting human beauty. In addition, this review also covers the prospect and challenge of using marine by-products toward the emerging concept of sustainable blue cosmetics.

Redox state associated with antitumor and immunomodulatory peptides in cancer

Cancer, a major public health problem, is the fourth cause of death in the world. While cancer mortality has decreased in recent decades due to more effective treatments, mostly based on improving antitumor immunity, some forms of cancer are resistant to these immunotherapies. A promising approach for cancer treatment involves the administration of antitumor and immunomodulatory peptides. Immunomodulatory peptides have been proved to exert antitumor and immunomodulatory effects by activating immune cells such as cytotoxic T cells, with fewer side-effects. A process closely related to the regulation of the immune system by immunomodulatory antitumor peptides is the modulation of the redox state, which has been poorly studied. This review focuses on the redox state regulated by antitumor and immunomodulatory peptides in cancer development, and on the potential of redox state as a therapy associated with these peptides in cancer treatment.

A Novel Fermented Rapeseed Meal, Inoculated with Selected Protease-Assisting Screened B. subtilis YY-4 and L. plantarum 6026, Showed High Availability and Strong Antioxidant and Immunomodulation Potential Capacity

A study was conducted to investigate the yield of small peptides from rapeseed meal (RSM) by solid-state fermentation (SSF) with acid-protease-assisting B. subtilis YY-4 and L. plantarum CICC6026 (FRSMP). This study explored the availability, antioxidant capacity and immunomodulation activity. The objective of this study was to develop a novel functional food ingredient to contribute to health improvement. The results showed that the concentrations of soluble peptides and free amino acids significantly increased after fermentation (p < 0.001), and the concentration of small molecular peptides (molecular weight < 1 KDa) significantly increased (p < 0.001). The dense surface microstructure of the RSM after fermentation was changed to be loose and porous. The FRSMP exhibited high availability and high antioxidant activity, and it displayed high immunomodulation activity. The novel fermentation was effective for improving the nutritional and biological properties, which provided a feasible method of enhancing the added value.

Physiological and Clinical Aspects of Bioactive Peptides from Marine Animals

Biological molecules in nutraceuticals and functional foods have proven physiological properties to treat human chronic diseases. These molecules contribute to applications in the food and pharmaceutical industries by preventing food spoilage and cellular injury. Technological advancement in the screening and characterization of bioactive peptides has enabled scientists to understand the associated molecules. Consistent collaboration among nutritionists, pharmacists, food scientists, and bioengineers to find new bioactive compounds with higher therapeutic potential against nutrition-related diseases highlights the potential of the bioactive peptides for food and pharmaceutic industries. Among the popular dietary supplements, marine animals have always been considered imperative due to their rich nutritional values and byproduct use in the food and pharmaceutical industries. The bioactive peptides isolated from marine animals are well-known for their higher bioactivities against human diseases. The physiological properties of fish-based hydrolyzed proteins and peptides have been claimed through in vitro, in vivo, and clinical trials. However, systematic study on the physiological and clinical significance of these bioactive peptides is scarce. In this review, we not only discuss the physiological and clinical significance of antioxidant and anticancer peptides derived from marine animals, but we also compare their biological activities through existing in vitro and in vivo studies.

Twelve Antioxidant Peptides From Protein Hydrolysate of Skipjack Tuna (Katsuwonus pelamis) Roe Prepared by Flavourzyme: Purification, Sequence Identification, and Activity Evaluation

For using aquatic by-products to manufacture high-value products, Skipjack tuna (Katsuwonus pelamis) roes were degreased, pretreated with microwave, and hydrolyzed using five proteases. The protein hydrolysate (TRPH) generated using Flavourzyme displayed the strongest 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. Twelve antioxidative peptides were prepared from TRPH by ultrafiltration and chromatography methods and determined to be SGE, VDTR, AEM, QDHKA, TVM, QEAE, YEA, VEP, AEHNH, QEP, QAEP, and YVM with molecular weights of 291.24, 489.50, 349.41, 597.59, 349.44, 475.42, 381.36, 343.37, 606.58, 372.35, 443.42, and 411.49 Da, respectively. AEM, QDHKA, YEA, AEHNH, and YVM presented the strongest scavenging activity on DPPH radical (EC₅₀ values of 0.250±0.035, 0.279±0.017, 0.233±0.012, 0.334±0.011, and 0.288±0.015 mg/ml, respectively), hydroxyl radical (EC₅₀ values of 0.456±0.015, 0.536±0.021, 0.476 ± 0.051, 0.369 ± 0.052, and 0.413 ± 0.019 mg/ml, respectively), and superoxide anion free radical (EC₅₀ values of 0.348 ± 0.018, 0.281 ± 0.013, 0.305 ± 0.022, 0.198 ± 0.011, and 0.425 ± 0.021 mg/ml, respectively). Moreover, AEM, QDHKA, YEA, AEHNH, and YVM presented high lipid peroxidation inhibition ability, Ferric-reducing power, and significant protective function on H₂O₂-induced Chang liver cells. Therefore, AEM, QDHKA, YEA, AEHNH, and YVM could be natural antioxidant ingredients used in pharmaceutical and functional products.

Protective effects of crude chalaza hydrolysates against liver fibrogenesis via antioxidation, anti-inflammation/anti-fibrogenesis, and apoptosis promotion of damaged hepatocytes

Four-hundred metric-ton chalazae are produced annually from the liquid-egg processing and always cause a heavy burden due to handling cost in Taiwan. After chalazae were hydrolyzed by protease A, the amounts of hydrophobic, aromatic, and branched-chain amino acids, as well as anserine were dramatically increased. This study was to understand the antifibrogenic effects of protease A-digested crude chalaza hydrolysates (CCH-As) on livers of thioacetamide (TAA) treated rats. CCH-As improved (P< 0.05) growth performance, serum liver damage indices, histopathological liver inflammation, and liver collagen deposition in TAA-treated rats. The antifibrogenic effects of CCH-As were due to decreased (P < 0.05) inflammatory/fibrogenic cytokine contents, α-smooth-muscle-actin (α-SMA) protein expression, and matrix metallopeptidase (MMP)-2 and -9 activities, as well as increased (P < 0.05) the antioxidant capacity in livers. CCH-As also increased (P < 0.05) cleaved caspase-3 and cleaved poly ADP-ribose polymerase protein levels in livers of TAA-treated rats which accelerating cell renewal. Thus, this study does not only reveal a novel nutraceutical ingredient, CCH-As, against liver fibrogenesis, but also offer an alternative way to expand the utilization of poultry byproducts.

Recent Advances in Marine-Based Nutraceuticals and Their Health Benefits

The oceans have been the Earth's most valuable source of food. They have now also become a valuable and versatile source of bioactive compounds. The significance of marine organisms as a natural source of new substances that may contribute to the food sector and the overall health of humans are expanding. This review is an update on the recent studies of functional seafood compounds (chitin and chitosan, pigments from algae, fish lipids and omega-3 fatty acids, essential amino acids and bioactive proteins/peptides, polysaccharides, phenolic compounds, and minerals) focusing on their potential use as nutraceuticals and health benefits.

Bioactive peptides from food fermentation: A comprehensive review of their sources, bioactivities, applications, and future development

Bioactive peptides (BPs) are specific protein fragments that exert various beneficial effects on human bodies and ultimately influence health, depending on their structural properties and amino acid composition and sequences. By offering promising solutions to solve diverse health issues, the production, characterization, and applications of food-derived BPs have drawn great interest in the current literature and are of particular interest to the food and pharmaceutical industries. The microbial fermentation of protein from various sources is indubitably a novel way to produce BPs with numerous beneficial health effects. Apart from its lower cost as compared to enzymes, the BPs produced from microbial fermentation can be purified without further hydrolysis. Despite these features, current literature shows dearth of information on the BPs produced from food via microbial fermentation. Hence, there is a strong necessity to explore the BPs obtained from food fermentation for the development of commercial nutraceuticals and functional foods. As such, this review focuses on the production of BPs from different food sources, including the extensively studied milk and milk products, with emphasis on microbial fermentation. The structure-activity (antihypertensive, antioxidant, antimicrobial, opiate-like, anti-inflammatory, anticancer/antiproliferative, antithrombotic, hypolipidemic, hypocholesterolemic, and mineral binding) relationship, potential applications, future development, and challenges of BPs obtained from food fermentation are also discussed.

Purification and characterization of antioxidant peptides from yak (Bos grunniens) bone hydrolysates and evaluation of cellular antioxidant activity

In this study, papain and alcalase were used to generate antioxidant peptides from yak bone protein. The antioxidant activities of hydrolysates in vitro were evaluated by 2,2'-azinobios-(3-ethylbenzothiazoline-6-sulphonic acid) radical scavenging activity, total reducing power, ferrous ion chelating ability and hydroxyl radical scavenging activity. The hydrolysates generated by alcalase possessed the best antioxidant activity among unhydrolyzed protein and samples treated by papain, but the antioxidant activity decreased after simulated gastrointestinal digestion in vitro. The products of simulated gastrointestinal digestion were separated by ultrafiltration and high performance liquid chromatography, and the amino acid sequences of peptides were identified by mass spectrometry. The digestion sites within peptides were predicted by a bioinformatics strategy, and ten peptides were selected for synthesis. Among 10 synthetic peptides, Gly-Phe-Hyp-Gly-Ala-Asp-Gly-Val-Ala, Gly-Gly-Pro-Gln-Gly-Pro-Arg and Gly-Ser-Gln-Gly-Ser-Gln-Gly-Pro-Ala possessed strong antioxidant activities, among which Gly-Phe-Hyp-Gly-Ala-Asp-Gly-Val-Ala had a significant cytoprotective effect in Caco-2 cells under oxidative stress induced by H₂O₂, which reduced the formation of reactive oxygen species and malondialdehyde, and improved the activity of antioxidant enzymes in cells. These results showed that yak bone peptides exhibited strong antioxidant activity and have a potential value as a new type of natural antioxidant.

Identification and characterization of novel antioxidant peptides from mackerel (Scomber japonicus) muscle protein hydrolysates

Antioxidant peptides are commonly used as functional ingredient in the pharmaceutical industries. Here, we characterized the antioxidant peptides from mackerel muscle protein hydrolysates (MPHs). MPHs showing higher bioactivities were separated into seven groups by FPLC. MPH-3 which exhibited significantly higher (p < 0.05) DPPH scavenging activity (32.12 ± 3.01%) was fractionated using RP-HPLC to obtain purified fractions A and B, which were further subjected to MALDI-TOF/TOF-MS for mass fingerprinting. Fraction A exhibited the highest (p < 0.05) DPPH scavenging activity (34.11 ± 1.52%), and it contained 21 peptides characterized by LC-MS/MS-. Ten peptides were synthesized, and their antioxidant activities were evaluated; one of the peptides, ALSTWTLQLGSTSFSASPM, showed the highest (p < 0.05) DPPH scavenging activity (36.34 ± 4.64%) and another peptide, LGTLLFIAIPI, exhibited the highest (p < 0.05) SOD-like activity (28.94 ± 4.19%). The results of this study indicate that MPHs could serve as a suitable source of antioxidant peptides.

Alternative extraction techniques to obtain, isolate and purify proteins and bioactive from aquaculture and by-products

Oceans cover more than 70% of the earth's surface and provide a great ecosystem for habitat of a large divers of marine species. The marine species are rich sources of bioactive compound that can be applied in medicine, pharmacology and food industry. Besides the marine species, fish processing industry also produces substantial volumes of by-products that can be used for a variety of purposes. Thus, it is important to find approaches to access to these valuable compounds. Nowadays, more factors have been considered in selecting an appropriate method for extraction of bioactive compounds such as consume less time and solvent, to be fast and ecofriendly. Concerns regarding entering the pollutions to the environment resulted to invest on the methods practicable with less chemical solvents and even green ones, however, implementation of stricter regulations and policies is required to encourage researchers to set up the procedures with reduced toxic agents to guarantee the environmental safety. In the current chapter the most common marine derived compounds and innovative methods for their extraction will be discussed.

Identification and characterization of the peptides with calcium-binding capacity from tilapia (Oreochromis niloticus) skin gelatin enzymatic hydrolysates

The aim of this study was to isolate and identify the peptides with calcium-binding capacity from the different tilapia skin gelatin enzymatic hydrolysates. The complex protease was selected and its hydrolysates were further separated using gel filtration chromatography (Sephadex G-25) and reverse phase high-performance liquid chromatography. Two purified peptides with strong calcium-binding capacity were identified as Tyr-Gly-Thr-Gly-Leu (YGTGL, 509.25 Da) and Leu-Val-Phe-Leu (LVFL, 490.32 Da). The calcium-binding capacities of YGTGL and LVFL reached 76.03 and 79.50 µg/mg, respectively. The structures of the complex of purified peptides and calcium (YGTGL-Ca and LVFL-Ca) were characterized by ultraviolet-visible spectroscopy (UV-VIS), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and mass spectrometry (LC-MS/MS). The results of UV-VIS, SEM, and XRD indicated that YGTGL-Ca and LVFL-Ca were formed as new compounds. The results of FTIR and LC-MS/MS indicated the nitrogen atom of the amino group and the oxygen atom of the carboxyl group in terminates of the peptides provided primary binding sites. Moreover, the hydrophobic amino acids in purified peptides could provide more chelating spaces. This study was of great significance for the development of calcium supplement foods. PRACTICAL APPLICATION: Compared with inorganic calcium and organic calcium, the bioactive gelatin peptide chelated calcium has the characteristics of high utilization rate, high solubility, and high absorption rate. The raw materials are extracted from the tilapia processed waste, which reduce the cost, make full use of resources, and improve the bioavailability. The tilapia skin gelatin peptide calcium chelate can be directly absorbed by the human body, and the absorption efficiency is high, further improving the resource utilization rate and having high economic benefits, which is a comprehensive supplement that can also be used as a functional food.

Antioxidant Peptides from the Protein Hydrolysate of Spanish Mackerel (Scomberomorous niphonius) Muscle by in Vitro Gastrointestinal Digestion and Their In Vitro Activities

For the full use of Spanish mackerel (Scomberomorous niphonius) muscle to produce antioxidant peptides, the proteins of Spanish mackerel muscle were separately hydrolyzed under five kinds of enzymes and in vitro gastrointestinal digestion, and antioxidant peptides were isolated from the protein hydrolysate using ultrafiltration and multiple chromatography methods. The results showed that the hydrolysate (SMPH) prepared using in vitro GI digestion showed the highest degree of hydrolysis (27.45 ± 1.76%) and DPPH radical scavenging activity (52.58 ± 2.68%) at the concentration of 10 mg protein/mL among the six protein hydrolysates, and 12 peptides (SMP-1 to SMP-12) were prepared from SMPH. Among them, SMP-3, SMP-7, SMP-10, and SMP-11 showed the higher DPPH radical scavenging activities and were identified as Pro-Glu-Leu-Asp-Trp (PELDW), Trp-Pro-Asp-His-Trp (WPDHW), and Phe-Gly-Tyr-Asp-Trp-Trp (FGYDWW), and Tyr-Leu-His-Phe-Trp (YLHFW), respectively. PELDW, WPDHW, FGYDWW, and YLHFW showed high scavenging activities on DPPH radical (EC₅₀ 1.53, 0.70, 0.53, and 0.97 mg/mL, respectively), hydroxyl radical (EC₅₀ 1.12, 0.38, 0.26, and 0.67 mg/mL, respectively), and superoxide anion radical (EC₅₀ 0.85, 0.49, 0.34, and 1.37 mg/mL, respectively). Moreover, PELDW, WPDHW, FGYDWW, and YLHFW could dose-dependently inhibit lipid peroxidation in the linoleic acid model system and protect plasmid DNA (pBR322DNA) against oxidative damage induced by H₂O₂ in the tested model systems. In addition, PELDW, WPDHW, FGYDWW, and YLHFW could retain their high activities when they were treated under a low temperature (<60 °C) and a moderate pH environment (pH 5–9). These present results indicate that the protein hydrolysate, fractions, and isolated peptides from Spanish mackerel muscle have strong antioxidant activity and might have the potential to be used in health food products.

Preparation and Evaluation of Peptides with Potential Antioxidant Activity by Microwave Assisted Enzymatic Hydrolysis of Collagen from Sea Cucumber Acaudina Molpadioides Obtained from Zhejiang Province in China

The present study was focused on the preparation and characterization of the antioxidant peptides by microwave-assisted enzymatic hydrolysis of collagen from sea cucumber Acaudina molpadioides (ASC-Am) obtained from Zhejiang Province in China. The results exhibited the effects of microwave irradiation on hydrolysis of ASC-Am with different protease. Neutrase was selected from the four common proteases (papain, pepsin, trypsin, and neutrase) based on the highest content and DPPH scavenging activity of hydrolysate Fa (Molecular weight < 1 kDa). The content and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity of Fa obtained by hydrolysis of neutrase increased by 100% and 109% respectively at a microwave power of 300 W compared with no microwave irradiation. Five subfractions were obtained after performing the gel filtration chromatography, and the Fa.2 exhibited the highest DPPH scavenging activity. The amino acid analysis showed that the contents of Glutamic acid, Alanine, Tyrosine, and Phenylalanine in fraction Fa.2 increased significantly, but an obvious decrease in the content of Glycine was observed compared to Fa. Four peptides (Fa.2-A, Fa.2-B, Fa.2-C, and Fa.2-D) were purified from Fa.2 by high performance liquid chromatography, and Fa.2-C showed the highest DPPH scavenging activity. The sequence of Fa.2-C was identified as Phenylalanine-Leucine- Alanine-Proline with a half elimination ratio (EC₅₀) of 0.385 mg/mL. The antioxidant activity of Fa.2-C was probably attributed to the small molecular sizes and the presence of hydrophobic amino acid residues in its sequence. This report provided a promising method for the preparation of antioxidant peptides from collagen for food and medicinal purposes.

Novel Bioactive Peptides from Meretrix meretrix Protect Caenorhabditis elegans against Free Radical-Induced Oxidative Stress through the Stress Response Factor DAF-16/FOXO

The hard clam Meretrix meretrix, which has been traditionally used as medicine and seafood, was used in this study to isolate antioxidant peptides. First, a peptide-rich extract was tested for its protective effect against paraquat-induced oxidative stress using the nematode model Caenorhabditis elegans. Then, three novel antioxidant peptides; MmP4 (LSDRLEETGGASS), MmP11 (KEGCREPETEKGHR) and MmP19 (IVTNWDDMEK), were identified and were found to increase the resistance of nematodes against paraquat. Circular dichroism spectroscopy revealed that MmP4 was predominantly in beta-sheet conformation, while MmP11 and MmP19 were primarily in random coil conformation. Using transgenic nematode models, the peptides were shown to promote nuclear translocation of the DAF-16/FOXO transcription factor, a pivotal regulator of stress response and lifespan, and induce the expression of superoxide dismutase 3 (SOD-3), an antioxidant enzyme. Analysis of DAF-16 target genes by real-time PCR reveals that sod-3 was up-regulated by MmP4, MmP11 and MmP19 while ctl-1 and ctl-2 were also up-regulated by MmP4. Further examination of daf-16 using RNA interference suggests that the peptide-increased resistance of C. elegans to oxidative stress was DAF-16 dependent. Taken together, these data demonstrate the antioxidant activity of M. meretrix peptides, which are associated with activation of the stress response factor DAF-16 and regulation of the antioxidant enzyme genes.

Bioactive properties: enhancement of hepatoprotective, antioxidant and DNA damage protective effects of golden grey mullet protein hydrolysates against paracetamol toxicity

This study was undertaken to examine the hepatoprotective, antioxidant, and DNA damage protective effects of protein hydrolysates from Liza aurata, against paracetamol overdose induced liver injury in Wistar rats. L. aurata protein hydrolysates (LAPHs) were mainly constituted by glutamic acid (Glu) and glutamine (Gln) and lysine (Lys). In addition, they contained high amounts of proline (Pro), leucine (Leu) and glycine (Gly). The molecular weight distribution of the hydrolysates was determined by size exclusion chromatography, which analyzed a representative hydrolysate type with a weight range of 3-20 kDa. The hepatoprotective effect of LAPHs against paracetamol liver toxicity was investigated by in vivo assay. Rats received LAPHs daily by gavage, for 45 days. Paracetamol was administrated to rats during the last five days of treatment by intraperitoneal injection. Paracetamol overdose induced marked liver damage in rats was noted by a significant increase in the activities of serum aspartate amino transferase (AST) and alanine amino transferase (ALT), and oxidative stress which was evident from decreased activity of the enzymatic antioxidants (superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx)), and level of glutathione (GSH), and increased concentration of lipid peroxidation products (MDA). Furthermore, paracetamol increased the DNA damage with liver histopathological changes. LAPH pretreatment significantly attenuated paracetamol-induced hepatotoxic effects, including oxidative damage, histopathological lesions, and apoptotic changes in the liver tissue. Interestingly, LAPHs restored the activities of antioxidant enzymes and the level of GSH, ameliorated histological and molecular aspects of liver cells. The present data suggest that paracetamol high-dose plays a crucial role in the oxidative damage and genotoxicity of the liver and therefore, some antioxidants such us LAPHs might be safe as hepatoprotectors. Altogether, our studies provide consistent evidence of the beneficial effect of LAPHs on animals treated with a toxic dose of paracetamol and might encourage clinical trials.

Antioxidative study of Cerium Oxide nanoparticle functionalised PCL-Gelatin electrospun fibers for wound healing application

Skin wound healing involves a coordinated cellular response to achieve complete reepithelialisation. Elevated levels of reactive oxygen species (ROS) in the wound environment often pose a hindrance in wound healing resulting in impaired wound healing process. Cerium oxide nanoparticles (CeNPs) have the ability to protect the cells from oxidative damage by actively scavenging the ROS. Furthermore, matrices like nanofibers have also been explored for enhancing wound healing. In the current study CeNP functionalised polycaprolactone (PCL)-gelatin nanofiber (PGNPNF) mesh was fabricated by electrospinning and evaluated for its antioxidative potential. Wide angle XRD analysis of randomly oriented nanofibers revealed ∼2.6 times reduced crystallinity than pristine PCL which aided in rapid degradation of nanofibers and release of CeNP. However, bioactive composite made between nanoparticles and PCL-gelatin maintained the fibrous morphology of PGNPNF upto 14 days. The PGNPNF mesh exhibited a superoxide dismutase (SOD) mimetic activity due to the incorporated CeNPs. The PGNPNF mesh enhanced proliferation of 3T3-L1 cells by ∼48% as confirmed by alamar blue assay and SEM micrographs of cells grown on the nanofibrous mesh. Furthermore, the PGNPNF mesh scavenged ROS, which was measured by relative DCF intensity and fluorescence microscopy; and subsequently increased the viability and proliferation of cells by three folds as it alleviated the oxidative stress. Overall, the results of this study suggest the potential of CeNP functionalised PCL-gelatin nanofibrous mesh for wound healing applications.

Tasar silk fiber waste sericin: New source for anti-elastase, anti-tyrosinase and anti-oxidant compounds

The present study investigates the properties of sericin extracted from tasar silk fiber waste (TSFW). The surface morphology of TSFW was observed by scanning electron microscope (SEM). SEM images revealed the removal of residual sericin over the surface of TSFW. The molecular weight distribution of sericin was examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The results suggested that TSFW sericin represented a family of proteins with wide-ranging molecular weight distribution (11-245 kDa). Structural determination by FTIR revealed the presence of both α-helical and β-sheet structures. The colour was studied by colorimeter indicating less brightness, more red and yellow colour intensities. The carbon: nitrogen ratio (C:N) was studied by CHNS element analyzer and the ratio is 5.15-7.85. Thermal properties of TSFW sericin have been studied by thermogravimetric analysis (TGA) method. TGA curve showed higher thermal stability and variable degradation profiles. Furthermore, TSFW sericin contains 17 amino acids where serine, aspartic acid and glycine are the more significant compounds (54.34-60.49%). In addition, sericin was found to inhibit tyrosinase, elastase and glutathione-S-transferase activity, and had apparent radical scavenging impacts on 2.2‑diphenyl‑1‑picryl‑hydrazil (DPPH), hydrogen peroxide and inhibition of lipid peroxidation. Result suggested that TSFW sericins might be a valuable ingredient for cosmoceutical products.

Transepithelial Transport of YWDHNNPQIR and Its Metabolic Fate with Cytoprotection against Oxidative Stress in Human Intestinal Caco-2 Cells

Studies on antioxidant peptides extracted from foodstuff sources have included not only experiments to elucidate their chemical characteristics but also to investigate their bioavailability and intracellular mechanisms. This study was designed to clarify the absorption and antioxidative activity of YWDHNNPQIR (named RAP), which is derived from rapeseed protein using a Caco-2 cell transwell model. Results showed that 0.8% RAP (C₀ = 0.2 mM, t = 90 min) could maintain the original structure across the Caco-2 cell monolayers via the intracellular transcytosis pathway, and the apparent drug absorption rate (P_app) was (6.6 ± 1.24) × 10^-7 cm/s. Three main fragments (WDHNNPQIR, DHNNPQIR, and YWDHNNPQ) and five modified peptides derived from RAP were found in both the apical and basolateral side of the Caco-2 cell transwell model. Among these new metabolites, WDHNNPQIR had the greatest antioxidative activity in Caco-2 cells apart from the DPPH assay. With a RAP concentration of 200 μM, there were significant differences in four antioxidative indicators (T-AOC, GSH-Px, SOD, and MDA) compared to the oxidative stress control (P < 0.05). In addition, RAP may also influence apoptosis of the Caco-2 cells, which was caused by AAPH-induced oxidative damage.

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.

Antioxidant activities of a peptide derived from chicken dark meat

Antioxidant activities against hypochlorite ions and peroxyl radicals of a chicken dark meat hydrolysate digested with pepsin were examined with the myoglobin method based on the structure change of myoglobin due to redox reaction with reactive oxygen species (ROS). A peptide that showed strong antioxidant activity against the peroxyl radical was isolated from the hydrolysate using HPLC equipped with a hydrophobic-interacting column. The sequence of the first five amino acid residues of the peptide was determined as YASGR (Tyr-Ala-Ser-Gly-Arg), and this sequence matched with the amino acid residues 143-147 of chicken β-actin (GenBank: CAA25004.1). The synthetic peptide YASGR showed very high antioxidant activity against the peroxyl radical. Antioxidant activities of the free amino acids, confirmed that the tyrosine residue of this peptide was possibly responsible for antioxidant activity.

Preventive effect of Nile tilapia hydrolysate against oxidative damage of HepG2 cells and DNA mediated by H2O2 and AAPH

Antioxidant activities of protein hydrolysate prepared from Nile tilapia protein isolate using Alcalase (HA), Alcalase followed by papain (HAPa) and their Sephadex G-25 fractions (FHA and FHAPa) were investigated in both chemical and cellular based models. Amongst all samples, FHAPa showed the highest chemical antioxidant activities, however it had no metal chelation activity. Cellular antioxidant ability of HA, HAPa and their fractions against H2O2 and AAPH induced oxidative damage of HepG2 cell and DNA were tested. When cells were pretreated with all hydrolysates or fractions at different concentrations (0.5-2 mg/mL) in the absence and presence of 50 μM Trolox, cell viability was in the range of 91.10-111.40 %. However, no difference in cell viability was observed among samples having various concentrations (P > 0.05). Cell reactive oxygen species (ROS) generation as mediated by H2O2 and AAPH decreased with treatment of hydrolysates or their fractions, especially in combination with 50 μM Trolox. FHAPa effectively inhibited H2O2 and peroxyl radical induced DNA scission in a dose dependent manner. Therefore, Nile tilapia protein hydrolysates could serve as a functional food ingredient.

Marine Peptides: Bioactivities and Applications

Peptides are important bioactive natural products which are present in many marine species. These marine peptides have high potential nutraceutical and medicinal values because of their broad spectra of bioactivities. Their antimicrobial, antiviral, antitumor, antioxidative, cardioprotective (antihypertensive, antiatherosclerotic and anticoagulant), immunomodulatory, analgesic, anxiolytic anti-diabetic, appetite suppressing and neuroprotective activities have attracted the attention of the pharmaceutical industry, which attempts to design them for use in the treatment or prevention of various diseases. Some marine peptides or their derivatives have high commercial values and had reached the pharmaceutical and nutraceutical markets. A large number of them are already in different phases of the clinical and preclinical pipeline. This review highlights the recent research in marine peptides and the trends and prospects for the future, with special emphasis on nutraceutical and pharmaceutical development into marketed products.

Influence of Amino Acid Compositions and Peptide Profiles on Antioxidant Capacities of Two Protein Hydrolysates from Skipjack Tuna (Katsuwonus pelamis) Dark Muscle

Influence of amino acid compositions and peptide profiles on antioxidant capacities of two protein hydrolysates from skipjack tuna (Katsuwonus pelamis) dark muscle was investigated. Dark muscles from skipjack tuna were hydrolyzed using five separate proteases, including pepsin, trypsin, Neutrase, papain and Alcalase. Two hydrolysates, ATH and NTH, prepared using Alcalase and Neutrase, respectively, showed the strongest antioxidant capacities and were further fractionated using ultrafiltration and gel filtration chromatography. Two fractions, Fr.A3 and Fr.B2, isolated from ATH and NTH, respectively, showed strong radical scavenging activities toward 2,2-diphenyl-1-picrylhydrazyl radicals (EC₅₀ 1.08% ± 0.08% and 0.98% ± 0.07%), hydroxyl radicals (EC₅₀ 0.22% ± 0.03% and 0.48% ± 0.05%), and superoxide anion radicals (EC₅₀ 1.31% ± 0.11% and 1.56% ± 1.03%) and effectively inhibited lipid peroxidation. Eighteen peptides from Fr.A3 and 13 peptides from Fr.B2 were isolated by reversed-phase high performance liquid chromatography, and their amino acid sequences were determined. The elevated antioxidant activity of Fr.A3 might be due to its high content of hydrophobic and aromatic amino acid residues (181.1 and 469.9 residues/1000 residues, respectively), small molecular sizes (3–6 peptides), low molecular weights (524.78 kDa), and amino acid sequences (antioxidant score 6.11). This study confirmed that a smaller molecular size, the presence of hydrophobic and aromatic amino acid residues, and the amino acid sequences were the key factors that determined the antioxidant activities of the proteins, hydrolysates and peptides. The results also demonstrated that the derived hydrolysates and fractions from skipjack tuna (K. pelamis) dark muscles could prevent oxidative reactions and might be useful for food preservation and medicinal purposes.

Identification and characterization of antioxidant peptides from enzymatic hydrolysates of duck meat

The objective of this study was to prepare antioxidant peptides from duck meat hydrolysate (DMH) using Protamex. The DPPH(•) scavenging activity, hydroxyl radical ((•)OH) scavenging activity, and Fe(2+)-chelating ability of DMH were investigated. DMH was separated into three groups, MWCO-1 (69.57%), MWCO-2 (9.53%), and MWCO-3 (8.21%), by ultrafiltration. MWCO-3 exhibited the highest DPPH(•) scavenging activity (83.17 ± 0.73%) and was subsequently fractionated by using gel filtration chromatography to obtain fraction B (40.90%). Fraction B5 (6.71%) obtained from ion exchange chromatography exhibited the highest DPPH(•) scavenging activity (93.63 ± 0.13%) and contained seven peptides which were characterized by LC-MS/MS. Among these peptides, LQAEVEELRAALE showed the highest DPPH(•) scavenging activity (93.36 ± 0.53%) and Fe(2+)-chelating ability (87.13 ± 0.47%) and IEDPFDQDDWGAWKK exhibited the highest (•)OH scavenging activity (46.51 ± 0.16%). The results presented here indicated that DMH could serve as a suitable source of antioxidant peptides.

Effect of tannic acid–fish scale gelatin hydrolysate hybrid nanoparticles on intestinal barrier function and α-amylase activity

Tannic acid/FSGH nanoparticles can ameliorate Cu²⁺ ion induced intestinal epithelial TJ dysfunction without severely inhibiting the activity of digestive enzymes.