Chemical composition and immunomodulatory effects of enzymatic protein hydrolysates from common carp (Cyprinus carpio) egg

Gastrointestinal digestion of food proteins: Anticancer, antihypertensive, anti-obesity, and immunomodulatory mechanisms of the derived peptides

Food proteins and their peptides play a significant role in the important biological processes and physiological functions of the body. The peptides show diverse biological benefits ranging from anticancer to antihypertensive, anti-obesity, and immunomodulatory, among others. In this review, an overview of food protein digestion in the gastrointestinal tract and the mechanisms involved was presented. As some proteins remain resistant and undigested, the multifarious factors (e.g. protein type and structure, microbial composition, pH levels and redox potential, host factors, etc.) affecting their colonic fermentation, the derived peptides, and amino acids that evade intestinal digestion are thus considered. The section that follows focuses on the mechanisms of the peptides with anticancer, antihypertensive, anti-obesity, and immunomodulatory effects. As further considerations were made, it is concluded that clinical studies targeting a clear understanding of the gastrointestinal stability, bioavailability, and safety of food-based peptides are still warranted.

Purification and characterization of a novel immunoregulatory peptide from Sipunculus nudus L. protein

This study aimed to purify and characterize immunoregulatory peptides from Sipunculus nudus L. and to explore the underlying mechanisms. Ultrafiltration, gel filtration chromatography, and reverse phase high-performance liquid chromatography (RP-HPLC) were used to purify the peptide following enzymatic hydrolysis. Rates of lymphocyte proliferation and phagocytosis as well as nitric oxide (NO) production levels were used as indicators of immunoregulatory activity to screen the fractions. The amino acid sequence of the peptide, designated as SNLP, was identified as Arg-Val-Lys-Gly-Lys-Ile-Leu-Ala-Lys-Arg-Leu-Asn (RVKGKILAKRLN) by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Treatment with the synthetic SNLP increased the proliferation and phagocytosis of RAW 264.7 macrophages and promoted the secretion of tumor necrosis factor-ɑ (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β), and NO levels. The mRNA levels of these cytokines and iNOS were also increased by SNLP. Our results provide preliminary evidence suggesting that SNLP acts as a dual immunomodulatory peptide with immunostimulatory and anti-inflammatory activities. In summary, SNLP derived from Sipunculus nudus L. is a potent immunoregulatory peptide and represents a potential functional food or immunoregulatory drug.

Immune Enhancement of Clam Peptides on Immunosuppressed Mice Induced by Hydrocortisone

Clam peptides, marine-derived biological peptides, have been broadly investigated and applied as health foods, among which immunomodulation is one of their biological activities that cannot be ignored in vivo. In this study, we concentrated on exploring the effects of Ruditapes philippinarum peptides (RPPs) on immunomodulation and the balance of intestinal microbiota in hydrocortisone (HC)-induced immunosuppressed mice. The results revealed that RPPs could increase the thymus and spleen indices and number of white blood cells, promote the secretion level of cytokines (IL-2, IL-6, TNF-α, and INF-γ), repair the morphology of the spleen and thymus, and enhance the proliferation of T-lymphocyte subsets in immunosuppressed mice. Moreover, RPPs improved the abundance of beneficial bacteria and preserved the ecological equilibrium of the gut microbiota. In conclusion, RPPs have significant immunomodulatory effects on immunosuppressed mice and may be developed as immunomodulators or immune adjuvants in functional foods and drugs; they are also beneficial to the utilization of the high value of marine shellfish.

Use of fungal and bacterial protease preparations to enhance extraction of lipid from fish roe: effect on lipidomic profile of extracted oil

•

Lipid extraction of fish roe was evaluated after hydrolysis with HT, FP-II and Alcalase proteases.

•

Alcalase hydrolysis of fish roe protein was more extensive than that of HT and FP-II.

•

The highest total lipid yield was obtained following hydrolysis of fish roe with Alcalase.

•

Alcalase hydrolysis achieved the greatest degree of hydrolysis and yielded less oxidised lipid.

•

The yield of omega-3 fatty acids and phospholipids was highest after HT hydrolysis.

The present study investigated the hydrolysis of protein in hoki roe homogenate using a HT (bacterial), a FP-II (fungal) protease preparations and Alcalase (bacterial) to enhance lipid yield extraction. The degree of hydrolysis was determined at various pH, temperature and time using casein and hoki roe. Total lipid extraction and lipidomic analysis was carried out following proteolysis of hoki roe homogenate. The degree of hydrolysis and SDS-PAGE revealed that the hydrolytic capability of Alcalase was better than HT and FPII. The total extracted lipid yield was better following hydrolysis with Alcalase (19.29 %), compared to HT (18.29 %) and FPII (18.33 %). However, the total phospholipid (PL) and n-3 fatty acid yields were better from HT hydrolysed hoki roe homogenate (PL = 30.7 μmol/g; n-3 = 10.5 %), compared to Alcalase (PL = 22 μmol/g; n-3 = 5.95 %). Overall, this study indicates that HT protease preparation hydrolysis of fish roe homogenate can both enhance lipid extraction and retain lipid quality.

Purification, Identification and Molecular Docking of Immunomodulatory Peptides from the Heads of Litopenaeus vannamei

In order to realize the high-value utilization of Litopenaeus vannamei (L. vannamei) heads, immunomodulatory peptides were prepared from the enzymatic hydrolysate of L. vannamei heads, and the action mechanism of immunomodulatory peptides was determined by molecular docking. The results showed that six proteases were used to hydrolyze L. vannamei head proteins, with the animal protease hydrolysate exhibiting the highest macrophage relative proliferation rate (MRPR). The enzymatic products were then sequentially purified by ultrafiltration, Sephadex G-15 gel chromatography, identified by liquid chromatography-mass spectrometry (LC-MS/MS), and finally selected for six immunomodulatory peptides (PSPFPYFT, SAGFPEGF, GPQGPPGH, QGF, PGMR, and WQR). These peptides maintained good immune activity under heat treatment, pH treatment, and in vitro gastrointestinal digestion. Molecular docking analysis indicated that these peptides showed great binding to both toll-like receptor 2 and 4 (TLR2 and TLR4/MD-2), leading to immunomodulation. The discarded L. vannamei heads in this article are considered to be promising food-borne immunomodulators that contribute to enhancing the immune function of the body.

Effect of milk protein hydrolysate supplementation on protein energy malnutrition-induced gut dysbiosis

Dairy proteins in the diet are beneficial for the growth of probiotics; however, what is unknown is the gut-mediated immune responses under protein energy malnutrition (PEM) and if dairy protein hydrolysates can be effective as dietary interventions. This study compares the composition of the gut microbiota of rats with moderate protein deficiency (M.PEM) and severe protein deficiency (S.PEM) induced by feeding 5% and 1% hypoprotein diets, followed by replenishment with buffalo and whey protein hydrolysates. Fecal samples were collected, and the composition of the gut bacteria was analyzed by whole genome sequencing using long-read sequencing. Gene expression studies of the immunomodulatory cytokines involved and quantification of sIgA were carried out. IL-6 and IFN-γ were downregulated by about 0.17 ± 0.06 and 0.12 ± 0.10 fold when supplemented with whey protein hydrolysate in SP-RWC rats and by about 0.02 ± 0.06 and 0.35 ± 0.12 fold when using buffalo milk hydrolysate. The percentage of Firmicutes decreased in M.PEM and S.PEM rats (33.57%, 28.83 versus 47.73% of control at 3 weeks) but increased upon protein replenishment for all three protein sources at the end of nine weeks. The percentage of Bacteroidetes increased to 31.03% in S.PEM-induced rats as against 28.17% in control rats. The relative abundance of Lactobacillus sp. decreased in M.PEM and S.PEM rats while it showed the opposite effect upon protein replenishment. Gut microbiota modulated the pathogenesis of PEM differentially based on protein intervention along with a significant increase in the relative abundance of the keystone Lactobacillus genus.

Aqueous Extracts of Fish Roe as a Source of Several Bioactive Compounds

Regular consumption of seafood and, in particular, fish has been associated with important health benefits. A fish product that has been increasingly included in the human nutrition is roe. Despite its nutritional value has been established (fatty acid profile and protein content), the knowledge of the composition of its aqueous extracts is still limited. This work describes the bioactive compounds profile in the roe-derived aqueous extracts of three different marine species (sardine, horse mackerel and sea bass) using a method based on liquid chromatography coupled to high-resolution mass spectrometry with an electrospray ionisation source (LC-ESI/HRMS). The presence of substances with well-known nutritional and functional properties (e.g., antioxidant and anti-inflammatory properties) was demonstrated, namely essential amino acids (e.g., taurine), peptides (e.g., anserine and carnosine), B-group vitamins (e.g., nicotinamide) and gadusol. Therefore, roe-derived aqueous extracts are excellent sources of bioactive compounds and may be used as a font of functional components for several medical and veterinary applications.

Comparison of physicochemical properties of different tissues from China climbing perch Anabas testudineus and crucian carp Carassius auratus

This study aimed to investigate nutrition in climbing perch Anabas testudineus which is an important nutritious economic freshwater fish in Asia and compare with Carassius auratus (crucian carp). Three kinds of tissues, including muscle, livers, and eggs, were isolated, respectively. Physicochemical properties including moisture, ash, protein, amino acids, fat, vitamins, and calcium contents in those tissues were determined. The results showed climbing perch muscle and liver contained less moisture, but more protein, amino acids, and vitamins than crucian carp muscle and liver. While moisture, ash, protein, and total amino acids contents of climbing perch egg were lower than those of crucian carp egg. Climbing perch egg had more fat, vitamins, and calcium than crucian carp egg. The amino acid profile was also performed, and 16 amino acids were identified and quantified in muscle, liver, and egg. Among tissues, the highest and lowest concentration of total amino acid content was found in crucian carp eggs and livers, respectively. Glutamic acid (Glu) and histidine (His) were the most and least amino acids in climbing perch and crucian carp tissues, respectively. Sixteen amino acids in climbing perch egg were less than those in crucian carp egg while it is an opposite case in muscle and liver, which amino acids of climbing perch tissues were more than those of crucian carp muscle and liver. Vitamin A of climbing perch was more than crucian carp in all three tissues, but vitamin E content in climbing perch liver was lower than that of crucian carp liver. Calcium content of muscle had no difference between two species. The abovementioned comparison of physicochemical properties of different tissues from China climbing perch and crucian carp will provide a necessary supplementary of freshwater muscle nutrition research, also was helpful for application of climbing perch.

Influence of the extent of enzymatic hydrolysis on the functional properties of protein hydrolysates from visceral waste of Labeo rohita

The study aimed to evaluate the extent of hydrolysis on the functional properties of fish protein hydrolysates from fish wastes. Fish protein hydrolysate (FPH) was prepared from the visceral waste of Rohu (Labeo rohita) using Alcalase^®. Independent variables of the hydrolysis conditions, namely, time, temperature and enzyme-substrate ratio were optimized through response surface methodology using a completely randomized factorial design. Functional properties of FPH, such as antioxidant activity, metal chelating activity, emulsifying and foaming capacity were studied. Pre-heating of the raw viscera resulted 83% reduction of lipid content in the FPH. The DH was found to be significantly influenced by the hydrolysis conditions studied. The gel electrophoretic study showed that FPH contained peptides in the range of < 10-25 kDa. Optimum degree of hydrolysis (DH) was obtained as 34.7% at 87.5 min, 48.64 °C and enzyme concentration of 0.99%. The results demonstrated that the antioxidant and metal chelating properties of FPH increased with the increase of DH. The surface active properties like emulsifying and foaming capacity were found to be decreased with the increased levels of hydrolysis. These results suggest that hydrolysates from visceral waste of Rohu could find potential use as supplement in animal feed.

Fish protein hydrolysates as a health-promoting ingredient-recent update

Dietary habits and lifestyle-related diseases indicate that food has a direct impact on individual health. Hence, a diet containing essential nutrients is important for healthy living. Fish and fish products are important in diets worldwide because of their nutritional value, especially their easily digestible proteins with essential amino acids. Similarly, fish protein hydrolysate (FPH) obtained from fish muscle and by-products has been reported to exhibit various biological activities and to have functional properties, which make FPH a suitable nutraceutical candidate. This review focuses on the health-promoting ability of FPH in terms of skin health, bone and cartilage health, blood lipid profile, and body-weight management studied in rats and human model systems. The absorption and bioavailability of FPH in humans is discussed, and challenges and obstacles of FPH as a functional food ingredient are outlined.

Purification and Identification of Novel Antioxidant Peptides from Enzymatically Hydrolysed Samia ricini Pupae

The emergence of excessive free radicals leads to the destruction of various systems within the body. These free radicals also affect nutritional values, color, taste, and emit an odor akin to rancid food. Most food industries use synthetic antioxidants, such as BHT (butylated hydroxytoluene) or BHA (butylated hydroxy anisole). However, high doses of these can be harmful to our health. Therefore, an antioxidant compounds, such as bioactive peptides from edible animals or plants, have emerged to be a very promising alternative as they reduce potential side effects. This study focused on the purification and identification of antioxidant peptides from protein hydrolysates of wild silkworm pupae (Samia ricini). Antioxidant peptides were purified from the hydrolysate by ultrafiltration and RP-HPLC. The results showed that protein hydrolysate from S. ricini pupae by trypsin with a molecular weight lower than 3 kDa and highly hydrophobic property, exhibited strong DPPH radical scavenging activity and chelating activity. Further identification of peptides from the fraction with the highest antioxidant activity was carried out using LC-MS/MS. Three novel peptides, i.e., Met-Ley-Ile-Ile-Ile-Met-Arg, Leu-Asn-Lys-Asp-Leu-Met-Arg, and Glu-Asn-Ile-Ile-Leu-Phe-Arg, were identified. The results of this study indicated that the protein hydrolysate from S. ricini pupae possessed potent biological activity, and the novel antioxidant peptides could be utilized to develop health-related antioxidants in food industry.

The impact of caseinate oligochitosan-glycation by transglutaminase on amino acid compositions and immune-promoting activity in BALB/c mice of the tryptic caseinate hydrolysate

Caseinate was glycated with oligochitosan via transglutaminase (TGase) action and then hydrolyzed by trypsin to generate glycated caseinate hydrolysate (GCNH) that was investigated for in vivo immune-promoting activity. Caseinate hydrolysate (CNH) containing glucosamine of 5.7 g/kg had amino acid compositions similar to GCNH. In normal BALB/c mice, GCNH at 100-400 mg/(kg d) showed higher immune-promoting activity than CNH via increasing serum IgM, IgA, and IgG by 1.5-24.5%, enhancing spleen and thymus indices by 9.7-26.2%, or increasing splenocyte lymphocyte proliferation and natural killer (NK) cell activity by 1.2-11.5%. GCNH also exerted higher activity than CNH in the suppressed BALB/c mice through increasing serum IgM, IgA, and IgG by 2.6-10.5%, enhancing spleen and thymus indices by 0.4-50.1%, or increasing splenocyte lymphocyte proliferation and NK cell activity by 3.4-18.9%. The results highlight that this TGase-type oligochitosan-glycation is potential to generate functional protein ingredients that possess improved immune-promoting activity once hydrolyzed by trypsin.

Pseudosciaena crocea roe protein-stabilized emulsions for oral delivery systems: In vitro digestion and in situ intestinal perfusion study

Benzyl isothiocyanate (BITC) was encapsulated in oil-in-water emulsions stabilized by Pseudosciaena crocea roe protein isolate (PRPI). The stability, lipid digestion, BITC bioavailability, and retention rate of the emulsions were characterized using a simulated gastrointestinal tract model. Tween-corn and PRPI-medium-chain triglycerides (MCT) emulsions were used as controls. The membrane permeability and BITC absorption from these emulsions were investigated by in situ single-pass intestinal perfusion. The results showed that the PRPI-stabilized emulsions were stable under nonacidic environment conditions. Moreover, the PRPI-corn emulsion had more obvious protective effects than PRPI-MCT and Tween-corn emulsions. Atomic force and confocal laser scanning microscopy images showed that the protein hydrolyzed and oil droplets aggregated during simulated gastric phase digestion. Following the exposure of oil droplets in the small intestine phase, the PRPI-corn emulsion had a high rate of free fatty acid release (99.13 ± 2.49%), and the retention rate and bioavailability of BITC from the PRPI-corn emulsion were 75.93 ± 7.17% and 77.32 ± 5.36%, respectively, which were significantly higher than those measured for the other emulsions (P < 0.05). Moreover, the K_a and P_eff of the PRPI-corn emulsion reached the maximum value at 45 min and then decreased slowly. These results suggest that the PRPI-corn emulsion delivery system is effective in encapsulating, delivering, and protecting BITC. PRACTICAL APPLICATION: This study provides some useful information for the food industry to develop a Pseudosciaena crocea roe protein isolate (PRPI) emulsion that could be successfully used to construct a BITC delivery system and improve benzyl isothiocyanate (BITC) bioavailability. The protective effect on BITC assessed in vitro simulated gastrointestinal tract and in situ single-pass intestinal perfusion are discussed.

Exoenzyme-producing halophilic bacteria from the former Lake Texcoco: identification and production of n-butyl oleate and bioactive peptides

Halophilic bacterias from saline soil from former Lake Texcoco were isolated, identified based on 16 rRNA and tested to produce glucolytic, nucleolytic, proteolytic and lipolytic exoenzymes. The Bacillus, Virgibacillus, Kocuria, Salinicoccus, Gracilibacillus, Halobacillus, Tenuibacillus and Nesterekonia genera where identified. Lipase/eserases and proteases from Nesterenkonia sp. and Nesterenkonia aethiopica showed halotolerant characteristics and were selected to synthesize the oleochemical n-butyl oleate and antioxidant peptides from muscle protein of common carp (Cyprinus carpio), respectively. In organic media (2,2,4-Trimethylpentane), the lipase/esterases from Nesterenkonia sp. (0.6 U/mL) and N. aethiopica (1.2 U/mL) achieved a 62.7% and 53.2% of n-butyl oleate conversion, respectively. The protein hydrolysis from muscle of common carp (C. carpio) showed a degree of hydrolysis of 4.5 ± 0.2% and 2.8 ± 0.1% when proteases from Nesterenkonia sp. and N. aethiopica were used, respectively. Three peptidic fractions ranging molecular masses between 254 and 1002 Da [M + H] show antioxidant scavenging activity, and the principal fraction with a peptide of 547.3 Da [M + H] showed an inhibition of 37.7 ± 1.8% and 16.3 ± 0.6%, when 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) were used, respectively. These findings showed that the enzymatic battery of the halophilic bacteria from former lake Texcoco can be used in hydrolysis and synthesis of molecules with applications in different fields as food technology or bioenergy.

Effect of Peptides from Alaska Pollock on Intestinal Mucosal Immunity Function and Purification of Active Fragments

The intestinal mucosal barrier plays an important role in systemic immune functions. This study aimed to find the mechanism of peptide from Alaska Pollock (APP) on intestinal mucosal immunity in mice induced by cyclophosphamide (Cy). Cy-induced decreases of body weight and index of immune organ were significantly improved by APP as compared with Cy group (p < 0.05). APP could promote the secretion of SIgA and IgA on intestinal mucosa (p < 0.05) and mainly had an impact on the final differentiation of IgA⁺ B cell, thereby promoting the secretion of plasma cells, which can be corroborated by the increases of IL-6 and IL-10 (p < 0.05). APP with high immune activity was separated and two peptides were purified and identified as Gly–Val–Ile–Lys and Ala–Cys–Asn–Gly–Arg. Therefore, APP can be considered as beneficial ingredients to protect the intestinal barrier disruption induced by Cy.

Bioactivities of enzymatic protein hydrolysates derived from Chlorella sorokiniana

Chlorella sorokiniana protein isolates were enzymatically hydrolyzed using pepsin, bromelain, and thermolysin, with their molecular characteristics and bioactivities determined. Thermolysin hydrolysates exhibited the highest degree of hydrolysis (18.08% ± 1.13%). The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) results showed that peptides with molecular weights <10 kDa were found in the hydrolysates compared to the protein isolates. Bioactivity assays revealed that pepsin peptide fraction <5 kDa showed the highest angiotensin-converting enzyme (ACE)-inhibitory (34.29% ± 3.45%) and DPPH radical scavenging activities (48.86% ± 1.95%), while pepsin peptide fraction <10 kDa demonstrated the highest reducing power with 0.2101% ± 0.02% absorbance. Moreover, antibacterial assessment revealed that pepsin hydrolysate and peptide fractions displayed inhibition to the test microorganisms. Overall, the present findings suggest that C. sorokiniana protein hydrolysates can be valuable bio-ingredients with pharmaceutical and nutraceutical application potentials.

Evaluation of the potential use of a carp (Cyprinus carpio) skin gelatine hydrolysate as an antioxidant component

Gelatine hydrolysates are of increasing interest as potential ingredients used in various health-promoting functional foods. Cyprinus carpio skin gelatine hydrolysates can be a potential source of bioactive peptides with antioxidant properties. Therefore, the aim of this research was to evaluate the potential use of a carp skin gelatine hydrolysate with proven antioxidant properties as a bioactive compound in functional foods as well as its stability under various processing conditions. The analysis of the hydrolysate included its characterisation (ζ-potential, particle size distribution), solubility, antioxidant ability and stability (DPPH, FRAP, chelating properties) under various conditions (heating, pH and NaCl). Additionally, an analysis of residual environmental pollutants (heavy metals, dioxins and pesticides) was also conducted. The hydrolysate had high solubility over a range of pH values from 2 to 12 (84%-98%), and its antioxidant properties remained stable in low concentration NaCl solutions as well as after being heated at temperatures between 40 and 100 °C. The hydrolysate was not contaminated with heavy metals, dioxins or pesticides. According to our study, carp skin hydrolysates can be incorporated into food processing systems without significant loss of their antioxidant activities.

Antimicrobial and Immunomodulatory Properties and Applications of Marine-Derived Proteins and Peptides

Marine organisms provide an abundant source of potential medicines. Many of the marine-derived biomaterials have been shown to act as different mechanisms in immune responses, and in each case they can significantly control the immune system to produce effective reactions. Marine-derived proteins, peptides, and protein hydrolysates exhibit various physiologic functions, such as antimicrobial, anticancer, antioxidant, antihypertensive, and anti-inflammatory activities. Recently, the immunomodulatory properties of several antimicrobial peptides have been demonstrated. Some of these peptides directly kill bacteria and exhibit a variety of immunomodulatory activities that improve the host innate immune response and effectively eliminate infection. The properties of immunomodulatory proteins and peptides correlate with their amino acid composition, sequence, and length. Proteins and peptides with immunomodulatory properties have been tested in vitro and in vivo, and some of them have undergone different clinical and preclinical trials. This review provides a comprehensive overview of marine immunomodulatory proteins, peptides, and protein hydrolysates as well as their production, mechanisms of action, and applications in human therapy.

Kinetics of angiotensin -1 converting enzyme inhibition and antioxidative properties of Azadirachta indica seed protein hydrolysates

Neem (Azadirachta indica) seed protein hydrolysates were investigated for in vitro antioxidant and angiotensin 1-converting enzyme (ACE)-inhibitory activities. Neem seed proteins were hydrolysed using pepsin, trypsin and Alcalase. The degree of pepsin hydrolysis of neem seed protein was significantly higher (p < 0.05) than those of trypsin and Alcalase hydrolysis. Proteolytic hydrolysis of the isolate resulted in hydrolysates with improved Arg/Lys ratio, with pepsin hydrolysates still being able to maintain an acceptable level of essential amino acids comparable to that of the isolate. At 2.5 mg/mL, pepsin neem seed protein hydrolysate (NSPH) demonstrated the strongest antioxidant activity with 67.15 % and 50.07 % DPPH- and superoxide anion radical-scavenging activities, respectively, while trypsin NSPH had the highest ferric-reducing power. Using N-[3-(2-furyl)acryloyl]-L-phenylalanyl-glycyl-glycine (FAPGG) as substrate, NSPHs strongly inhibited ACE (69.20–80.39 %) in a concentration-dependent manner. Pepsin NSPH had higher ACE-inhibitory activity than trypsin and Alcalase NSPHs. Kinetic studies showed the mechanism of ACE inhibition to be mixed-type with Ki values of 0.62, 0.84, 1.5 for pepsin, trypsin and alcalase NSPH, respectively. These results suggest that NSPH can be used as a potential nutraceutical with antioxidant capacity and inhibitory activity against ACE.

Fabrication and Physicochemical Characterization of Pseudosciaena crocea Roe Protein-Stabilized Emulsions as a Nutrient Delivery System

The aim of this study was to develop a protein emulsifier that can be used to construct a nutrient delivery system. Pseudosciaena crocea roe protein isolate (PRPI) was prepared and tested for its emulsifying properties. Benzyl isothiocyanate (BITC) was used as a model delivery nutrient in the constructed emulsions. The average particle size, zeta potential, and BITC retention rate of the emulsions were used as the main evaluation indexes, and confocal laser scanning microscopy was used to test the storage stability of the emulsions (composition: 5 mg/mL protein, 5% oil, 0 to 5 mg/mL BITC, pH 8). After storing at 20 °C for 7 days, the largest particle size of the emulsion at pH 8 increased from 274.27 to 280.82 nm. Storing at higher temperatures had a negative impact on the particle size and BITC retention rate. On the seventh day, the average particle size at 20 and 4 °C was 289.63 nm and 275.67 nm, respectively, and the BITC retention rate at 20 °C (83.30%) was found to be 15.50% lower than that at 4 °C (98.58%). These results demonstrate that the PRPI-based emulsion system is effective in protecting nutrients and has excellent stability at 4 °C. PRACTICAL APPLICATION: This study provides some useful information for the food industry to develop a nutrient delivery system emulsified with fish roe protein isolate. The properties of the isolated protein and its protective effect on nutrients are discussed.

An in vitro and in silico study on the antioxidant and cell culture-based study on the chemoprotective activities of fish muscle protein hydrolysates obtained from European seabass and gilthead seabream

European seabass (Dicentrarchus labrax, Linnaeus, 1758) (L) and gilthead seabream (Sparus aurata, Linnaeus, 1758) (C) muscles were hydrolysated by Alcalase (L_alc, C_alc) and Chymotrypsin (L_ch, C_ch) then hydrolysates were examined and their peptide profiles obtained. A total of 765, 794, 132 and 232 peptides were identified in C_alc, L_alc, C_ch and L_ch, respectively. Although, L_ch and C_ch were expected to have more antioxidant capacity because of their peptide profiles, Alcalase hydrolysates observed in vitro, were slightly higher (TEAC assay for C_alc: 848.11 ± 60.78 μmol TE/g protein). Maximum inhibition of oxidative stress was determined for L_alc (12.8% ± 4.5%) in MDCK1 cell lines. Highest proliferative capacity observed for C_alc (147.0% ± 3.1%) at MTT assay in MDCK1 cell culture. L_ch showed the highest chemopreventive effect with a 40-60% decrease for human colon adenocarcinoma cell line HT-29. This research points out the importance of aquatic sources as raw materials for peptide researches.

Immunomodulatory Protein Hydrolysates and Their Application

Immunomodulatory protein hydrolysate consumption may delay or prevent western immune-related diseases. In order to purposively develop protein hydrolysates with an optimal and reproducible immunomodulatory effect, knowledge is needed on which components in protein hydrolysates are responsible for the immune effects. Important advances have been made on this aspect. Also, knowledge on mechanisms underlying the immune modulating effects is indispensable. In this review, we discuss the most promising application possibilities for immunomodulatory protein hydrolysates. In order to do so, an overview is provided on reported in vivo immune effects of protein hydrolysates in both local intestinal and systemic organs, and the current insights in the underlying mechanisms of these effects. Furthermore, we discuss current knowledge and physicochemical approaches to identify the immune active protein sequence(s). We conclude that multiple hydrolysate compositions show specific immune effects. This knowledge can improve the efficacy of existing hydrolysate-containing products such as sports nutrition, clinical nutrition, and infant formula. We also provide arguments for why immunomodulatory protein hydrolysates could be applied to manage the immune response in the increasing number of individuals with a higher risk of immune dysfunction due to, for example, increasing age or stress.

Immunomodulating peptides for food allergy prevention and treatment

Among the most promising strategies currently assayed against IgE-mediated allergic diseases stands the possibility of using immunomodulating peptides to induce oral tolerance toward offending food allergens or even to prevent allergic sensitization. This review focuses on the beneficial effects of food derived immunomodulating peptides on food allergy, which can be directly exerted in the intestinal tract or once being absorbed through the intestinal epithelial barrier to interact with immune cells. Food peptides influence intestinal homeostasis by maintaining and reinforcing barrier function or affecting intestinal cell-signalling to nearby immune cells and mucus secretion. In addition, they can stimulate cells of the innate and adaptive immune system while supressing inflammatory responses. Peptides represent an attractive alternative to whole allergens to enhance the safety and efficacy of immunotherapy treatments. The conclusions drawn from curative and preventive experiments in murine models are promising, although there is a need for more pre-clinical studies to further explore the immunomodulating strategy and its mechanisms and for a deeper knowledge of the peptide sequence and structural requirements that determine the immunoregulatory function.

Enzymatic Processes in Marine Biotechnology

In previous review articles the attention of the biocatalytically oriented scientific community towards the marine environment as a source of biocatalysts focused on the habitat-related properties of marine enzymes. Updates have already appeared in the literature, including marine examples of oxidoreductases, hydrolases, transferases, isomerases, ligases, and lyases ready for food and pharmaceutical applications. Here a new approach for searching the literature and presenting a more refined analysis is adopted with respect to previous surveys, centering the attention on the enzymatic process rather than on a single novel activity. Fields of applications are easily individuated: (i) the biorefinery value-chain, where the provision of biomass is one of the most important aspects, with aquaculture as the prominent sector; (ii) the food industry, where the interest in the marine domain is similarly developed to deal with the enzymatic procedures adopted in food manipulation; (iii) the selective and easy extraction/modification of structurally complex marine molecules, where enzymatic treatments are a recognized tool to improve efficiency and selectivity; and (iv) marine biomarkers and derived applications (bioremediation) in pollution monitoring are also included in that these studies could be of high significance for the appreciation of marine bioprocesses.

Immunomodulatory and Antioxidant Effects of Polysaccharides from Gynostemma pentaphyllum Makino in Immunosuppressed Mice

The immunomodulatory and antioxidant activities of crude polysaccharides extracted from Gynostemma pentaphyllum Makino (GPMPP) were investigated. GPMPP was composed of rhamnose, arabinose, xylose, mannose, glucose and galactose in the molar ratio of 1.39:3.76:1.00:1.64:4.98:5.88. In vivo studies showed GPMPP significantly increased the spleen and thymus indices, activated the macrophage phagocytosis and NK cells, and exhibited activity on none or Con A/LPS-stimulated splenocytes in a dose-dependent manner in C57BL/6 mice. Moreover, GPMPP elevated CD4⁺ T lymphocyte counts as well as the CD4⁺/CD8⁺ ratio dose-dependently, and it increased IL-2 level in the sera and spleen of Cy-immunosuppressed mice. Furthermore, GPMPP significantly increased the SOD, GSH-Px, T-AOC, GSH and CAT level, and decreased the MDA level. The results showed that GPMPP might play an important role in prevention of oxidative damage in immunological system. These findings indicate GPMPP has immunomodulatory activity in vivo and seems to be an effective natural immunomodulatory agent.

Food-derived immunomodulatory peptides

Food proteins contain specific amino acid sequences within their structures that may positively impact bodily functions and have multiple immunomodulatory effects. The functional properties of these specific sequences, also referred to as bioactive peptides, are revealed only after the degradation of native proteins during digestion processes. Currently, milk proteins have been the most explored source of bioactive peptides, which presents an interesting opportunity for the dairy industry. However, plant- and animal-derived proteins have also been shown to be important sources of bioactive peptides. This review summarizes the in vitro and in vivo evidence of the role of various food proteins as sources of immunomodulatory peptides and discusses the possible pathways involving these properties. © 2016 Society of Chemical Industry.

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.

Antioxidant activity and functional properties of enzymatic protein hydrolysates from common carp (Cyprinus carpio) roe (egg)

Previously, we have reported the composition, molecular mass distribution and in vivo immunomodulatory effects of common carp roe protein hydrolysates. In the current study, antioxidative activity and functional properties of common carp (Cyprinus carpio) roe (egg) protein hydrolysates, prepared by pepsin, trypsin and Alcalase, were evaluated. The three hydrolysates showed excellent antioxidant activities in a dose dependent manner in various in vitro models such as 2,2 diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, 2,2'-azino-bis(3-ethylbenzthiazoline-6)-sulfonic acid (ABTS(+)) radical scavenging activity, ferric reducing antioxidant power (FRAP) and ferrous ion (Fe(2+)) chelating ability. Enzymatic hydrolysis significantly increased protein solubility of the hydrolysates to above 62 % over a wide pH range (2-12). Carp roe hydrolysates exhibited good foaming and emulsification properties. The results suggest that bioactive carp roe protein hydrolysates (CRPHs) with good functional properties could be useful in health food/nutraceutical/pharmaceutical industry for various applications.