Antioxidant activity of a peptide isolated from Alaska pollack (Theragra chalcogramma) frame protein hydrolysate

Valorisation of smooth hound (Mustelus mustelus) waste biomass through recovery of functional, antioxidative and antihypertensive bioactive peptides

Concerns over the environmental and waste disposal problems created by the large amounts of by-products generated from fish processing industries are increasing worldwide. The bioconversion of those marine waste by-products through the enzymatic hydrolysis of their protein content offers the possibility for the development of bioactive peptides for use in various biotechnological applications. The present study aimed to investigate and evaluate the biological and functional properties of smooth hound (Mustelus mustelus) protein hydrolysates (SHPHs) obtained by treatment with intestinal and gastric enzyme preparations from M. mustelus viscera and porcine pancreatin. The results revealed that the SHPHs exhibited different degrees of hydrolysis and antioxidant activity. The hydrolysate produced by the intestinal crude extract presented the highest rate of antioxidative activity, showing an IC50 value of 1.47 ± 0.07 mg/mL in 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging assays. The alkaline protease extract from the intestine of M. mustelus produced hydrolysate with the highest angiotensin I-converting enzyme (ACE) inhibitory activity (82 ± 1.52% at 2 mg/mL). All the protein hydrolysates showed excellent solubility and interfacial properties that were governed by pH. The major amino acids detected in SHPHs were glutamic acid/glutamine, aspartic acid/asparagine, histidine and arginine, followed by methionine, phenylalanine, serine, valine and leucine. Overall, the results indicated that smooth hound by-products can be used to generate high value-added products, thus offering a valuable source of bioactive peptides for application in wide range of biotechnological and functional food applications.

A hexameric peptide purified from Styela plicata protects against free radical-induced oxidative stress in cells and zebrafish model

To prepare antioxidative peptide from Styela plicata, nine proteases were employed for enzymatic hydrolysis, and the antioxidative activities of the hydrolysates were investigated using an electron spin resonance (ESR) spectrometer.

Antioxidant activities of rice bran protein hydrolysates in bulk oil and oil-in-water emulsion

BACKGROUND

Recently, utilization of natural antioxidants in food processing has been of growing interest, owing to the concerns of health hazards of synthetic agents. Protein hydrolysates are a potent candidate for this purpose. In this work, rice bran protein hydrolysates (RBPH) with various degrees of hydrolysis (DH) were prepared, and their antioxidant activities in soybean oil and oil-in-water (O/W) emulsion were examined.

RESULTS

With increasing DH, RBPH showed increasing antioxidant activities, as evidenced by the increases in DPPH radical scavenging activity, reducing power and ferrous chelating activity (P < 0.05). The improved activity was associated with increasing surface hydrophobicity (SoANS). After hydrolysis for 60 min, the content of hydrophobic amino acids was increased. When RBPH with various DH were incorporated into bulk soybean oil and O/W emulsion stored at 37 °C for up to 15 days, lipid oxidation was successfully retarded, especially when DH increased. The efficiency in prevention of oxidation was dose dependent (0-10 g L(-1)), as indicated by the lower peroxide value and thiobarbituric reactive substances.

CONCLUSION

The present work suggests that RBPH might be potently employed as a natural antioxidant in both bulk oil and emulsion models.

Purification and characterization of four antibacterial peptides from protamex hydrolysate of Atlantic mackerel (Scomber scombrus) by-products

Proteins from fish by-product sources are valuable source of bioactive peptides and show promise as functional foods ingredients. The objective of the present study was to isolate and characterize antibacterial peptides from protamex hydrolysates of Atlantic mackerel (Scomber scombrus) by-products. Four sequences SIFIQRFTT (P4), RKSGDPLGR (P8.1), AKPGDGAGSGPR (P8.2) and GLPGPLGPAGPK (P11) were identified in peptide fractions separated using RP-HPLC. At 200 μg mL(-1), while peptides P8.1, P8.2 and P11 exhibited partial inhibition, P4 totally inhibited tested Gram-positive (Listeria innocua) and Gram-negative (Escherichia coli) bacterial strains. These results suggest that the protein hydrolysate derived from mackerel by-products could be used as an antimicrobial ingredient in both functional food and nutraceutical applications.

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.

Radical scavenging and amino acid profiling of wedge clam, Donax cuneatus (Linnaeus) protein hydrolysates

Body, foot and viscera of Donax cuneatus (Linnaeus) were hydrolyzed using commercial proteases (pepsin, trypsin and papain) and tested for their antioxidant activity by DPPH scavenging ability and reducing power assays. In comparison between all the hydrolysates, papain viscera (28.513 ± 0.165 & 0.186 ± 0.008) and foot (33.567 ± 0.132 & 0.166 ± 0.013) hydrolysates showed highest DPPH and reducing power ability respectively. The active hydrolysates were purified with DEAE- cellulose followed by Sephadex G-25 columns connected to FPLC. Further, the isolated active fractions were loaded onto HPLC for their amino acid profiling and found with the presence of potential amino acids viz., histidine, cysteine, alanine etc. These results suggest that the isolated antioxidant peptide from viscera and foot hydrolysate of D. cuneatus can be used in treating human diseases where free radicals and oxidative damage are involved.

Transcriptomic and peptidomic analysis of protein hydrolysates from the white shrimp (L. vannamei)

An RNAseq approach associated to mass spectrometry was conducted to assess the composition, molecular mass distribution and primary sequence of hydrolytic peptides issued from hydrolysates of white shrimp (Litopenaeus vannamei) by-products. High performance size exclusion chromatography (HPSEC) analyses indicated that 69.2% of the 214-nm-absorbing components had apparent molecular masses below 1000 Da, and 88.3% below 2000 Da. OFFGEL-nLC-MALDI-TOF/TOF and nLC-ESI-MS/MS analyses led to the identification of 808 peptides based on the NCBI EST databank (161,397 entries) completed by the new L. vannamei databank (58,508 entries) that we created from the RNAs of tissues used for hydrolysate production. Whereas most of hydrolytic peptides have a MW below 2000 Da, preliminary investigations of antimicrobial properties revealed three antibacterial fractions that demonstrate functional activities. The abundance of small peptides as well as the biological activities detected could imply very interesting applications for shrimp hydrolysate in the field of aquaculture feeding.

Preparation of Antioxidant Hydrolysates from Round Scad (Decapterus maruadsi) Protein by Composite Enzymatic Hydrolysis

Round scad (Decapterus maruadsi) was hydrolyzed by composite enzymatic hydrolysis to obtain the hydrolysates possessing high antioxidant activity. The optimum conditions of antioxidant hydrolysates preparation by composite enzymatic hydrolysis were investigated. The results demonstrated that superior antioxidant activities (low IC50 values of radical scavenging activity and high reducing power) were obtained at an enzyme (a mixture of neutral protease and trypsin, 1:1 w/w) to substrate ratio of 0.3%, an incubation time of 5 h and an incubation temperature of 50 °C. Under the conditions, the recovery ratio of protein was 75.24% and the degree of hydrolysis was 25.86%

The influence of the extent of enzymatic hydrolysis on antioxidative properties and ACE-inhibitory activities of protein hydrolysates from goby (Zosterisessor ophiocephalus) muscle

Antioxidant properties and angiotensin-converting enzyme (ACE) inhibitory activities of protein hydrolysates from goby (Zosterisessor ophiocephalus) muscle, with different degrees of hydrolysis (DH) from 5 to 25%, prepared by treatment with crude proteases extract from smooth hound intestines, were investigated. Goby protein hydrolysates (GPHs) are rich in Gly and Thr, which accounted for 14.1-15% and 11.6-13.2% of the total amino acids, respectively. The antioxidant activities of GPHs were investigated by using several in vitro assay systems. All GPHs exhibited significant metal chelating activity and DPPH free radical-scavenging activity, and inhibited linoleic acid peroxidation. For the ACE-inhibitory activity, as the DH increased, the activity of GPHs increased. The obtained results revealed that antioxidant and ACE-inhibitory activities of GPHs were influenced by the degree of hydrolysis. A medium degree of enzymatic hydrolysis was appropriate to obtain GPHs with good antioxidant activity, while small peptides were essential to obtain high ACE inhibitory activity.

The effect of lactic acid bacteria fermentation on the antioxidant activity of wheat gluten pancreatin hydrolysates

The antioxidant activities of the fermented wheat gluten hydrolysates with different fermentation times were investigated to elucidate the impact of lactic acid bacteria (LAB) fermentation on the wheat gluten hydrolysates. Prior to LAB fermentation, wheat gluten was deamidated by hydrochloric acid and then hydrolysed by pancreatin to 12 and 24 h, respectively. Results showed that LAB fermentation had significant impacts on the enzymatic efficiency and antioxidant activities of wheat gluten. The degree of hydrolysis and protein recovery of hydrolysates gradually increased and then reached maximum values, respectively, when fermenting with LAB for 36 h. The hydrolysis degree and protein recovery of fermented pancreatin 24‐h hydrolysates were larger than that of the fermented pancreatin 12‐h hydrolysates during the whole fermentation. The antioxidant activity analysis revealed a marked increase and improvement in the scavenging activities of 1,1‐Diphenyl‐2‐picrylhydrazyl·radicals, hydroxyl radicals and oxygen radical absorbance capacity, while the scavenging activities of ABTS+ radical decreased as the fermentation time extended. The antioxidant activities of pancreatin 24‐h hydrolysates were higher than that of the pancreatin 12‐h hydrolysates during the whole LAB fermentation.

Identification of inherently antioxidant regions in proteins with radical-directed dissociation mass spectrometry

Antioxidant peptides such as glutathione play critically important roles within cells by opposing the action of oxidative species. Similarly all proteins may, as a secondary function, potentially contribute to the antioxidant capacity of the cellular milieu, though this possibility has not been thoroughly explored previously. Herein it is demonstrated that, in addition to radical quenching solution-phase behavior, antioxidant peptides display an astonishing ability to sequester radicals in the gas phase. Compared to other peptides of similar sequence and size, radical antioxidant peptides exhibit very little radical-directed dissociation when subjected to collisional activation in the gas phase. Importantly, this property can be leveraged in highly sensitive and rapid mass spectrometry based experiments to identify antioxidant peptides. Examination of peptides derived from human serum albumin (HSA), which is a protein known to behave as an antioxidant, revealed three previously unknown peptide regions that exhibit antioxidant capacity. One of these peptides, VAHRFK, shows antioxidant capacity comparable to that of glutathione. It is likely that these peptide regions contribute to the overall antioxidant capacity of HSA. In comparison with previous methods, the present technique is significantly more sensitive and less time-consuming, which should enable more wide-scale examination of antioxidant peptides that are relevant to redox homeostasis, food chemistry, and disease.

Antioxidative activity of protein hydrolysate produced by alcalase hydrolysis from shrimp waste (Penaeus monodon and Penaeus indicus)

Protein hydrolysates prepared by hydrolysis of shrimp waste (Penaeus monodon and Penaeus indicus) for 90 min. using Alcalase enzyme following pH-stat method. Antioxidative activities of SWPH were assessed determining FRAP, ABTS and DPPH radical scavenging activities, which increased linearly with increasing concentration of protein hydrolysate upto 5 mg/ml maintaining good correlation. SWPH showed high stability over wide ranges of pH (2-11) and temperature (up to 100 °C for 150 min), in which the activity of more than 80% was retained. Protein hydrolysate solution with a concentration of 5 mg/ml significantly lowered TBA values of Croaker fish fillet and maintained yellowishness of skin colour compared to untreated control sample during 10 days of refrigerated storage at 4 °C. SWPH also restricted the increase of PV and FFA values in Croaker fish fillet within acceptable limit.