Oxidative Stability of Common Kilka (Clupeonella cultriventris caspia) Oil Supplemented with Microwave Extracted Ghure (Unripe Grape) Marc Extract

The objective of this study was to evaluate the effect of microwave extracted Ghure (unripe grape) marc extract on common kilka (Clupeonella cultriventris caspia) oil oxidation during accelerated storage. The antioxidant activity of Ghure marc extract was compared with those of α-tocopherol and BHT. The Ghure marc extract significantly reduced the peroxide and p-anisidine value of kilka oil. Even though the effect of Ghure marc extract on reducing the oxidation of kilka oil was similar to the effect of BHT, it was functionally more effective than α-tocopherol. Generally, Ghure marc extract could be considered as a potential source of natural antioxidants, with inexpensive costs, for improving the oxidative stability of kilka oil.

Abbreviations: AA, Antioxidant activity; AOP, Antioxidant power; AV, p-Anisidine value; CUPRAC, Cupric ion reducing antioxidant capacity; DHA, Docosahexaenoic acid; EPA, Eicosapentaenoic acid; FIC, Ferrous ion chelating; GME, Ghure marc extract; FRAP, Ferrous ion reducing antioxidant power; KO, Kilka oil; IP, Induction period; MAE, Microwave-assisted extraction; MUFA, Monounsaturated fatty acid; PUFA, Polyunsaturated fatty acid; PV, peroxide value; PF, Protection factor; RSA, Radical scavenging activity; SFA, Saturated fatty acids; TFC, Total flavonoid content; TPC, total phenolic content TV, totox value.     

Antioxidant Properties of Protein Hydrolysate Obtained from Oyster Saccostrea cucullata (Born, 1778)

The antioxidant activities of enzymatically hydrolyzed (protease from Bacillus cereus SU12) oyster (Saccostrea cucullata) protein were studied. The hydrolysate exhibited a strong antioxidant potential in 1, 1-diphenyl-2-picrylhydrazyl (DPPH, 85.7 ± 0.37%), followed by hydrogen peroxide radical scavenging activity (81.6 ± 0.3%), hydroxyl radical scavenging activity (79.32 ± 0.6%), and reducing power assay (2.63 ± 0.2 OD at 700 nm) at a concentration of 1 mg/mL. Due to the high antioxidant potential, the hydrolysate was purified in Sephadex G-25 gel filtration chromatography. The active peptide fraction was identified by DPPH and reducing power assay. The amino acid content of the purified active peptide fraction was analyzed by high performance liquid chromatography. The active fraction contained a good quantity of both essential and nonessential amino acids. The present study revealed that oyster (S. cucullata) protein hydrolysate is a potential source for natural antioxidants.     

Antioxidant Potential of Water Hyacinth (Eichornia crassipes): In Vitro Antioxidant Activity and Phenolic Composition

The aims of the present study were (a) to extract and quantify the main phenolic acids and tocopherols from the petiole, leaves, and flowers of Eichornia crassipes; (b) to evaluate the antioxidant capacity of the extracts in four in vitro systems (1,1-diphenyl-2-pycryl-hydrazyl [DPPH] radical scavenging ability, iron chelating activity, reducing power, and prevention of oxidation in a liposome model system); and (c) its effectiveness in retarding lipid peroxidation in fish oil by accelerated stability test. Significant differences were observed in total and individual phenolic contents and in the antioxidant activities of extracts from the various parts of E. crassipes. Out of the 11 phenolic acids analyzed, ethanolic extracts contained high amounts of gallic, protocatechuic, gentisic, and p-hydroxybenzoic acid, whereas, water extracts contained less amounts of a varied number of phenolic acids. Ethanolic extracts of flower, which contained the highest total phenolic content, were found to have high DPPH radical scavenging activity and reducing power. However, ethanolic extracts of leaf exerted a high Fe²⁺ chelating activity and also inhibited lipid peroxidation process both in liposomes and fish oil. Our results demonstrate that E. crassipes, an underutilized aquatic weed, could be a potential natural antioxidant source for food, feed, and pharmaceutical applications.     

Antioxidant and Angiotensin-Converting Enzyme Inhibitory Activities of Protein Hydrolysates Prepared from Threadfin Bream (Nemipterus spp.) Surimi By-products

Solid wastes from threadfin bream (Nemipterus spp.) surimi production composed of head and frame were hydrolyzed by various commercial proteases (Alcalase, Flavourzyme, Neutrase, Protamex, papain, and pepsin) to produce protein hydrolysates with bioactive properties. An Alcalase-hydrolyzed sample at 24.4% degree of hydrolysis (DH) displayed the highest antioxidant activity based on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, ferric reducing antioxidant power (FRAP) assay, and potassium ferricyanide method. In addition, it showed an inhibitory activity toward angiotensin-converting enzyme (ACE) of 25.5%. Antioxidant activity of threadfin bream by-product hydrolysates increased with hydrolysis time and reached the highest DPPH activity after 6 h, while that hydrolyzed for 3 h showed the highest reducing power based on FRAP and potassium ferricyanide assays. In addition, ACE inhibitory activity was found to be at an optimum after 3 h of hydrolysis. The hydrolysates (1 mg/mL) also retarded oxidation of a linoleic acid emulsion system to a similar extent as 0.1 mg/mL 3-tert-butyl-4-hydroxy anisole (BHA), indicating a potential use in the food system. Protein hydrolysates from threadfin bream surimi by-products could be tailor-made to possess both antioxidant and ACE inhibitory activity through controlling DH of Alcalase-catalyzed reactions.     

Optimization of Antioxidant Peptides Production from the Mantle of Cuttlefish (Sepia pharaonis) Using RSM and Fractionation

Persian Gulf cuttlefish mantles were hydrolyzed (CPH) using alcalase, and the optimal hydrolysis parameters were obtained for the highest degree of hydrolysis (DH) and strongest antioxidant (based on their ability to quench 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals) activity using response surface methodology (RSM). The predicted optimal parameters of DH and quenching DPPH radicals was: pH of 7.88, 50.2°C, 150 min, and enzyme to substrate ratio of 1.5%. The reducing power (RP) and ability of optimized peptides to quench ABTS radicals in a gastro-intestinal track model system increased during the intestinal stage, while scavenging ability against DPPH radicals dropped (P < 0.05). The oxidation of lipid was retarded in a lecithin-liposome model added with optimized CPH in a concentration dependent response. Ultrafiltration of optimized CPH showed that the 3–10 KDa fraction had the greatest DPPH radical scavenging activity, the 10–30 KDa fraction had the highest reducing power, and the <3 KDa fraction had the greatest ABTS radical scavenging activity.     

Purification and Identification of an Antioxidative Peptide from Digestive Enzyme Hydrolysis of Cutlassfish Muscle

ABSTRACT

The major objective of this study was to investigate the pepsin digests of cutlassfish muscle for their antioxidant activity. The peptide isolated after 3 h of pepsin hydrolysis demonstrated the highest scavenging activity for both 1,1-Diphenyl-2-picrylhydrazyl (DPPH) and alkyl radicals. It also had the highest yield of the isolates with the highest protein content, which was likely related to its higher degree of hydrolysis than the other hydrolysates. The antioxidant peptide purified from the 3 h pepsin hydrolysate indicated the amino acid sequence, Phe-Ser-Gly-Gly-Glu. This study suggests that cutlassfish muscle is an excellent antioxidant source and could be effectively used as a food ingredient and in pharmaceuticals.     

Antioxidant Properties of Seven Cultivated and Natural Edible Seaweed Extracts from Taiwan

Seven species of cultivated and edible seaweeds found in Southern Taiwan—including Enteromorpha intestinalis, Monostorma nitidum, Ulva lactuca, Dictyopteris undulata, Sargassum hemiphyllum var. chinense, Laurencia intermedia, and Porphyra dentate—were used to determine their antioxidant activity by different extraction methods. All seaweeds were extracted using water at 90°C, sterilization at 121°C, homogenization, or enzymatic hydrolysis. Extracts were evaluated for their free radical-scavenging capacity using 1,1-diphenyl-2-pricrylhydrazyl (DPPH), their reducing power, and their superoxide anion scavenging activity. The DPPH-scavenging capacity of S. hemiphyllum var. chinense extracts produced by sterilization (98.59%), homogenization (94.72%), and carbohydrate-degrading enzyme treatment was higher than that of protease extracts, except for U. lactuca. The reducing power of S. hemiphyllum var. chinense water extracts and M. nitidum Viscozyme extracts was better than that of a commercial antioxidant. S. hemiphyllum var. chinense exhibited higher superoxide anion scavenging activity than the other species. The results demonstrate that different extracts of some of the seaweeds showed remarkable antioxidant activity in different assays. The results also provide important information for the marine food industry and suggest that seaweed might be a valuable source of natural antioxidants.     

Evaluation of the Antioxidant and Antimicrobial Activity of Protein Hydrolysates and Peptide Fractions Derived from Colossoma macropomum and Their Effect on Ground Beef Lipid Oxidation

The objective of this study was to obtain protein hydrolysate from the mechanically separated meat of blackfin pacu to evaluate the influence by ultrafiltration in the antioxidant and antimicrobial activities of the peptide fractions obtained and to apply in ground beef to evaluate the lipid stability. The enzymatic hydrolysis was performed using the enzyme Protamex (pH 7.0, 60°C) for 240 min. The protein hydrolysate was fractionated by ultrafiltration. Then, the antioxidant capacity of the protein hydrolysate and the peptide fractions were evaluated in vitro by the methods of 2,2’-azinobis (3-ethylbenzothiazoline sulfonic acid) radical capture, 2,2-diphenyl-1-picrylhydrazyl radical-scavenging assay, reducing power, and hydroxyl radical scavenging activity. The antimicrobial activity of the samples was evaluated by disc-diffusion against Staphylococcus aureus and Escherichia coli. After evaluation, the peptide fractions did not present higher bioactivities than that shown for the hydrolysate. The protein hydrolysate was applied to ground beef, where the substances reactive to thiobarbituric acid and color were evaluated during 7 days of storage at 4°C. Lipid oxidation was reduced up to 60.9% and there was no modification of the natural coloration. Thus, the protein hydrolysate can be used as an alternative source of antioxidant for the preservation of refrigerated meats.     

Effect of Degree of Hydrolysis and Protease Type on the Antioxidant Activity of Protein Hydrolysates From Cuttlefish (Sepia officinalis) By-Products

We have investigated the antioxidant activities of eight hydrolysates from cuttlefish by-products obtained by treatment with various gastrointestinal proteases (chymotrypsin, trypsin, and crude alkaline enzyme extracts from cuttlefish and sardinelle) and bacterial proteases (Alcalase and crude enzymes from Bacillus pumilus A1, Bacillus mojavensis A21, and Bacillus cereus BG1). The antioxidant activities of the cuttlefish by-products protein hydrolysates (CPHs) were evaluated using various in vitro antioxidant assays, such as 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity, reducing power, and total antioxidant capacity. All hydrolysates showed different degrees of hydrolysis (DH) and varying degrees of antioxidant activity. Among the different hydrolysates, cuttlefish crude enzyme hydrolysate exhibited the highest antioxidant activity, followed by sardinelle crude enzyme and Alcalase hydrolysates. Further, CPHs with different degrees of hydrolysis were prepared by treatment with proteolytic enzymes from cuttlefish, sardinelle, and B. mojavensis A21. All hydrolysates showed a greater antioxidative activity as indicated by all the methods considered. In addition, antioxidant activity in hydrolysates was positively correlated with the increase of DH. The results of this study indicated that CPHs might be a good candidate for further investigation in developing new antioxidants.     

Chemical Compositions and Antioxidant Activities of a Specialty Aquatic Vegetable Nymphoides hydrophylla in Taiwan

Nymphoides hydrophylla (NH), a lesser known aquatic vegetable, is a popular dish among the Hakka community in Taiwan. This study aimed to examine the proximate and polyphenolic compositions of NH and evaluate its antioxidant activities using various antioxidant assays. Results showed that the moisture, crude protein, crude fat, carbohydrate (crude fiber), and ash contents of fresh NH were 89.46, 0.46, 0.47, 4.11 (3.65), and 5.50%, respectively. In the antioxidant studies, the NH ethanolic extract (NH-E) exhibited higher antioxidant activities than the aqueous extract (NH-H) in the antilipid peroxidation, reducing power, metal chelation, and 2,2?-azino-bis(3-ethylbenthiazoline-6-sulfonic acid) or ABTS radical scavenging assays, while NH-H possessed more potent activity in the superoxide and 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays. Compared with NH-H (6.86 mg/g for total flavonoids and 48.83 mg/g for total phenolics), NH-E showed a higher content of total flavonoids (197.21 mg/g) and total phenolics (79.43 mg/g). High-performance liquid chromatography (HPLC) analysis showed that the main difference between NH-H and NH-E polyphenolic contents was derived from the concentrations of kaempferol and quercetin.     

Antioxidative Properties of Squid Protein Hydrolysates Prepared Using Seer Fish Visceral Enzymes in Comparison with Commercial Enzymes

ABSTRACT

In the present study, antioxidative potential of squid protein hydrolysates (SPH) prepared using endogenous pepsin and trypsin prepared from the stomach and pyloric ceca of seer fish respectively was evaluated, in comparison with commercial enzymes. Degree of hydrolysis (DH) of the pepsin SPH ranged between 8–11% and trypsin SPH between 12–14% after 150 min of hydrolysis. SPH prepared with endogenous enzymes had significantly higher DH than commercial enzymes. Pepsinogen SPH expressed more DH than pepsin SPH. Trypsin SPH exhibited good metal chelating ability (98%), which was equivalent to EDTA at 130 ppm. Pepsin SPH showed higher super oxide anion scavenging activity (75%). Trypsin and pepsin SPH also had high DPPH radical scavenging (85%), ABTS radical scavenging (93%) and ferric reducing (Abs700 = 1.2) abilities. Thus, metal chelating and superoxide anion radical scavenging activities of SPH are dependent on enzymes rather than DH.     

Assessment of Bioactive Potential of Aqueous Protein Extracts from Diatoms Nitzschia laevis,Spirulina platensis,and Chlorella vulgaris

The bioactivities of protein extracts from Nitzschia laevis, Spirulina platensis, and Chlorella vulgaris were evaluated in vitro. Free radical scavenging potential, reducing power, oxygen radical absorbance capacity, superoxide anion radical, xanthine oxidase inhibition, and potential to inhibit angiotensin 1-converting enzyme (ACE) and acetylcholinesterase enzyme (AChE) were studied. Nitzschia protein extracts showed the highest 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activities, reducing power, and ACE inhibitory activity. Spirulina’s proteins showed the highest 2,2′-Azino-bis (3 ethylbenzothiazoline-6-sulfonic acid) (ABTS) scavenging activity, xanthine oxidase, and AChE inhibition activities. Aqueous protein extracts from Nitzschia, Spirulina, and Chlorella showed in vitro antioxidant, anti-ACE, and anti-AChE activities, suggesting possible new sources of bioactive proteins of different phyla with nutraceutical and pharmaceutical potentials.     

Autolysis of Anchovy (Engraulis japonicus) Protein: Evaluation of Antioxidant Properties and Nutritional Quality of Resulting Hydrolysates

Protein hydrolysis of underutilized marine organisms is a method to improve added value. In the present article, anchovy protein was autolyzed at pH 8.5 and 50°C. After autolysis processing for 24 h, total nitrogen recovery reached 92.1%. The protein hydrolysates had antioxidant properties on reducing power, 1, 1-diphenyl-2-picryhydrazyl radical, and hydroxyl radical scavenging activity. More than 79% of the peptides in the hydrolysates had a molecular weight of lower than 3 kDa. Protein hydrolysates had balanced amino acid compositions, and total content of essential amino acids had no significant difference after hydrolysis. Protein hydrolysates from anchovy autolysis have potential in nutritional and functional foods.     

The extracts of Angelica sinensis inhibit lipid oxidation in fish erythrocytes and improve growth,digestive, absorptive and antioxidant capacity in juvenile Jian carp (Cyprinus carpio var. Jian)

The study explored the effects of ethyl ether extract, ethyl acetate extract (EAE), acetone extract, ethanol extract and aqueous extract of Angelica sinensis (EAs) and ethoxyquin (EQ) on lipid oxidation in erythrocytes and growth, digestive, absorptive and antioxidant capacity in carp (Cyprinus carpio var. Jian). The results indicated that EAs and EQ respectively at the concentrations of 0.5 and 0.25 mg/ml suppressed lipid oxidation by decreasing the generation of ROS and restoring the activities of antioxidants in hydroxyl radical‐treated erythrocytes. Of all of the examined EAs, EAE showed the strongest protective effects against lipid oxidation in carp erythrocytes. The antioxidant effects of EQ at the concentration of 0.25 mg/ml were stronger than that of EAE at the concentration of 0.5 mg/ml in fish erythrocytes. The antioxidative activities of EAs in carp erythrocytes were positively correlated with their phenols content. Moreover, dietary EAE raised growth performance in fish. The appropriate concentration of EAE for the growth of fish was estimated to be 3.544 g/kg diet. Dietary EAE increased digestive and absorptive capacity in carp and improved antioxidant capacity in copper‐treated carp. So, EAE could be used as a potential natural antioxidant and inhibitor of copper stress in fish.     

Anti-Inflammatory,Antioxidant, and Antimicrobial Effects of Underutilized Fish Protein Hydrolysate

Antimicrobial, anti-inflammatory, and antioxidant activities of protein hydrolysates from Argentine croaker (Umbrina canosai) protein isolate (CPI) or Argentine croaker myofibrillar protein with different degrees of hydrolysis (DH: 10–20%) prepared using Alcalase or Protamex were determined. Results showed that an increase in the DH resulted in higher content of hydrophobic and aromatic amino acids (AAAs) and in a decrease in molecular weight (MW) distribution for all hydrolysates obtained. Furthermore, the enzyme and raw material used influenced the amino acid content and MW determined. Hydrolysates from CPI with a 20% DH by Alcalase had higher 2,2?-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical scavenging activity, metal chelation, and ferric-reducing antioxidant power (p < 0.05). All hydrolysate samples decreased the pro-inflammatory capacity. In all the evaluated microorganisms, only seven were inhibited, most being Gram-positive. Alcalase was found to exert a considerable influence on antibacterial activity. These hydrolysates are an alternative as natural antimicrobials, anti-inflammatory, and antioxidant compounds.     

Antioxidant Assessment of Schizochytrium Meal Protein Enzymatic Hydrolysate and Its Potential Application

Schizochytrium meal protein (SMP) extracted from Schizochytrium meal was hydrolyzed by flavourzyme. Response surface methodology (RSM) was used to optimize the extraction conditions for the protein extraction yield from Schizochytrium meal. 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (DRSA) was used to evaluate the antioxidant activity of hydrolysates. The orthogonal test was used to investigate the effects of three independent variables, namely protease dosage, hydrolysis time, and pH. The optimum conditions obtained were as follows: protease dosage of 7%, hydrolysis time of 1.5 h, pH of 6, under which, DRSA at the concentration of 2 mg/mL was 89.38%. Aspartic and glutamic acid constituted approximately 26.32% of the total amino acids, and glutamic acid was the most abundant amino acid of Schizochytrium meal protein hydrolysate (SMPH) by amino acid composition analysis, which may have contributed to the scavenging activity of SMPH. Moreover, SMPH was made into chewable tablets with suitable formula and high humidity stability. These findings indicate that Schizochytrium meal can be reused as a raw material for preparation of antioxidant peptides.     

Improvement of Antioxidant Activity of Grass Carp (Ctenopharyngodon idella) Protein Hydrolysate by Washing and Membrane Removal Pretreatments and Ultrasonic Treatment

To improve the antioxidant activity of grass carp hydrolysate, washing and membrane removal pretreatments and ultrasonic treatment were applied in this study. Various pretreatment methods (washing methods and membrane removal methods) for removing the prooxidants and phospholipid in minced fish were evaluated. The effects of ultrasonic treatment prior to enzyme hydrolysis on the antioxidant activities of minced carp hydrolysate were investigated. The minced carp subjected to washing with 0.4% NaCl solution and subsequent membrane removal with CaCl₂ and citric acid solution had the lowest content of prooxidants and phospholipid remaining in the minced fish. The hydrolysate produced from washing/membrane removal pretreated carp with ultrasonic treatment for 20 min had the highest ferric reducing antioxidant power and scavenging activities against 1,1-diphenyl-2-picrylhydrazyl and 2,2?-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radicals. This suggested that the combination approach of washing/membrane removal pretreatment and ultrasonic treatment could improve the antioxidant activity of carp hydrolysate, and this hydrolysate could be a potential antioxidant ingredient for functional foods.     

Evaluation of Turmeric Extract as an Antioxidant for Frozen Streaked Prochilod (Prochilodus lineatus) Fillets

This study aimed to investigate the efficiency of turmeric (Curcuma longa L.) extract, applied as a marinade or glaze, as an antioxidant for frozen streaked prochilod (Prochilodus lineatus) fillets. The turmeric extract contained 5.5 ± 0.1 mg curcumin/mL, and the experiment was performed using a diluted extract with 100 µg curcumin/mL. Analysis of the antioxidant activity with 2,2-diphenyl-picrylhydrazyl (DPPH) and 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals confirmed the high antioxidant activity of curcumin. However, under the experimental conditions, curcumin extract presented no effectiveness for inhibiting lipid oxidation in frozen streaked prochilod fillets, as the concentration of thiobarbituric acid reactive substances did not differ (p > 0.05) between treated and control fillets. Sensory evaluation of the fillet appearance indicated that the change toward a more yellow color in treated fillets negatively affected its acceptance. However, the acceptability of the odor of raw and cooked fillets was similar for treated and control samples. These results may be explained by the fact that good in vitro performance of antioxidants is not always replicated in foodstuffs owing to the complexity of food matrices. Additionally, the low lipid content of the fish and the low amount of curcumin applied to the fillets may have contributed to the inefficiency of turmeric extract.     

Protein Hydrolysates and Ultrafiltration Fractions Obtained from Krill (Euphausia superba): Nutritional,Functional, Antioxidant,and ACE-Inhibitory Characterization

ABSTRACT

Krill (Euphausia superba) was hydrolyzed by proteolytic enzymes in order to produce multifunctional bioactive peptides, and their functional properties were evaluated. Krill protein hydrolysate (KPH) by pepsin with 4-h hydrolysis showed the highest 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging and angiotensin I converting enzyme (ACE) inhibitory activities. The solubility and foaming properties of KPH were higher than those of the unhydrolyzed krill protein at a wide range of pHs. KPH was further fractionated based on molecular weight. The 1- to 3-kDa peptide fraction exhibited the highest DPPH scavenging activity (IC₅₀ value of 0.5 mg/mL), oxygen radical absorbance capacity (497.39 ± 4.31 µM TE/mg fraction), 2,2-azino-bis(3-ethylbenzthiazoline)-6-sulfonic acid cation radical scavenging activity (48.41 ± 0.23 µM TE/mg fraction), and reducing power (110.40 ± 2.07 µM TE/mg fraction). However, the < 1-kDa peptide fraction exhibited a higher ACE inhibitory activity than that of other fractions. The 1- to 3- and < 1-kDa peptide fractions are rich in aromatic and hydrophobic amino acids, respectively.     

Evaluation of the Antioxidant Activity In Vitro and in Hippocampal HT-22 Cells System of Protein Hydrolysates of Common Carp (Cyprinus carpio) By-Product

Fish processing by-products may become more than 50% of the starting material. If mismanaged, these large quantities of discarded fish can create serious pollution problems and can also generate cost associated with their disposal. Enzymatic hydrolysis is one of the techniques that is currently being developed in order to recover and add value to these biomolecules. There is an increasing interest in natural antioxidants that are safer for consumers compared with synthetic antioxidants. In this study, common carp by-product was hydrolyzed using the enzymes Alcalase (A) and Protamex (P) to reach degrees of hydrolysis (DH) of 10 and 15%, respectively. Antioxidant capacity against peroxyl radicals (ACAP); 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging; and the measurement of intracellular reactive oxygen species (ROS) concentration after exposure to common carp protein hydrolysates were investigated. The results revealed that the hydrolysate A15 exhibited significantly (p < 0.05) higher antioxidant activity against the DPPH radical. A15 showed the highest in vitro antioxidant competence against peroxyl radicals, whereas P15 showed the lowest activity against peroxyl radicals (p < 0.05). Hydrolysates having the highest and the lowest in vitro antioxidant activity (A15 and P15, respectively) were selected for the determination of antioxidant activity in the HT-22 cells system. Measurement of intracellular ROS concentration revealed that P15 at the concentration of 1.25 mg/mL significantly (p < 0.05) reduced the intracellular ROS concentration. These results showed that common carp by-product protein hydrolysates are a source of antioxidant peptides with a high potential for food and pharmaceutical industries to develop new nutraceuticals and functional foods.