Characterisation of the lipid fractions obtained by proteolytic and chemical extractions from rainbow trout (Oncorhynchus mykiss) roe

Inhibitory effects of Oncorhynchus mykiss lipids in LPS-induced RAW264.7 cells via suppression of NF-κB and MAPK pathways

Oncorhynchus mykiss, a significant aquaculture species, possesses compounds with numerous biological and pharmacological functions, including antioxidant, anticancer, anti-microbial, and anti-obesity effects. However, possible anti-inflammatory effects of lipids extracted from O. mykiss eggs on RAW264.7 cells induced by LPS have not been elucidated yet. The current study identified 13 fatty acids in lipids extracted from O. mykiss eggs that contained high amounts (51.92% of total fatty acids) of polyunsaturated fatty acids (PUFAs), especially DHA (33.66%) and EPA (7.77%). These O. mykiss lipids (100-400 μg/mL) showed significant anti-inflammatory effects by inhibiting NO and iNOS expression in LPS-stimulated RAW264.7 cells. They also inhibited expression of pro-inflammatory cytokines IL-1β, IL-6, and TNF-α, while upregulating anti-inflammatory cytokines IL-10, IL-11, and TGF-β. These lipids from O. mykiss effectively inhibited LPS-induced expression CD86 as a surface biomarker on RAW264.7 cells. Additionally, O. mykiss lipids suppressed phosphorylation of p38, JNK, and ERK1/2 and the expression of phosphorylated NF-κB subunit p65. These findings indicate that O. mykiss lipids possess anti-inflammatory properties by inhibiting NF-κB and MAPK signaling pathways.

Anti-inflammatory properties of neutral lipids, glycolipids, and phospholipids isolated from Ammodytes personatus eggs in LPS-stimulated RAW264.7 cells

In the present study, total lipids were extracted from Ammodytes personatus eggs and separated into neutral lipids, glycolipids, and phospholipids. The anti-inflammatory activity of the neutral lipids, glycolipids, and phospholipids was investigated in macrophages, as well as the fatty acid profiles of the lipids. Palmitic acid, oleic acid, docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA) were the primary fatty acids in the three fractionated lipids. Among the lipids, the phospholipids contained the highest concentration of polyunsaturated fatty acids (PUFAs), particularly DHA and EPA (31.89 and 16.93% of the total fatty acids, respectively). The anti-inflammatory effects of the three lipids isolated from A. personatus eggs were analyzed in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. The three lipids significantly reduced nitric oxide (NO) production and the mRNA expression of immune-associated genes in a dose-dependent manner. All lipids down-regulated the protein expression of phosphorylated NF-κB-p65 and MAPK (p38, JNK, and ERK1/2) signaling pathways, suggesting that they could inhibit cell signaling pathways by activating NF-κB and MAPK. The expression of CD40 and CD86 in LPS-stimulated RAW264.7 cells was also significantly decreased by A. personatus lipids. Consequently, the neutral lipids, glycolipids, and phospholipids from A. personatus eggs could serve as anti-inflammatory agents.

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

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

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

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

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

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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.

Comparison of the Nutritional Composition of Bullfrog Meat from Different Parts of the Animal

The objective of this study was to evaluate the nutritional content of bullfrog meat from different parts of the animal, including fore-chest, thigh and calf. Bullfrog meat was found to be a rich source of proteins, essential amino acids and minerals, but with a low fat content, compared with other aquatic meat products. There was no significant difference (p>0.05) between thigh and calf in mineral content (K, P, Na, Mg, Ca, Zn, Fe, Cu, and Mn), but the contents of K, P, and Mg were higher in thigh and calf than in the fore-chest (p<0.05). The salt-soluble, water-soluble and insoluble protein bands in sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) electrophoresis, from fore-chest, thigh and calf were similar, with the most abundant bands being 35 kDa (salt-soluble protein), 35–48 kDa (water-soluble protein) and 48 kDa (insoluble protein). The results showed that the insoluble protein content in the fore-chest meat was higher than that in the thigh meat and calf meat, but the salt-soluble protein fraction was the most abundant in thigh meat. These results showed that the nutrients in different parts of bullfrog meat were different.

Immunomodulatory Activities of Ammodytes personatus Egg Lipid in RAW264.7 Cells

Ammodytes personatus, known as the Pacific sand lance, thrives in cold areas of the North Pacific. In this study, the total lipid was extracted from A. personatus eggs and the fatty acid composition was determined using gas chromatography (GC)-flame ionization detection (FID). The results showed that the extracted lipid contained high content of polyunsaturated fatty acids (PUFAs). The immunomodulatory activities of the A. personatus lipid were investigated using rodent macrophages. First, immune enhancement was analyzed, and the A. personatus lipid significantly and dose-dependently increased the NO production in RAW264.7 cells, and this lipid also regulated the transcription of immune-associated genes in RAW264.7 cells by activating the NF-κB and MAPK pathways. Additionally, flow cytometry revealed that this lipid stimulated phagocytosis. Conversely, the anti-inflammatory activity of the A. personatus lipid was also analyzed and the results showed significantly decreased NO production and gene expression in a dose-dependent manner in LPS-stimulated RAW264.7 cells. In addition, the A. personatus lipid suppressed the LPS-induced phosphorylation of proteins related to the NF-κB and MAPK pathways in LPS-stimulated RAW264.7 cells. Further, flow cytometry demonstrated the lipid-regulated anti-inflammatory activity via inhibition of CD86 expression. The results indicate that A. personatus egg lipid is a potential source of immunomodulation.

Accelerated Solvent Extraction and Pulsed Electric Fields for Valorization of Rainbow Trout (Oncorhynchus mykiss) and Sole (Dover sole) By-Products: Protein Content, Molecular Weight Distribution and Antioxidant Potential of the Extracts

Fishery by-products are rich in biologically active substances and the use of green and efficient extraction methods to recover these high-added-value compounds is of particular importance. In this study, head, skin and viscera of rainbow trout and sole were used as the target matrices and accelerated solvent extraction (ASE) (45–55 °C, 15 min, pH 5.2–6.8, 103.4 bars) and pulsed electric fields (PEF) (1–3 kV/cm, 123–300 kJ/kg, 15–24 h) were applied as extraction technologies. The results showed that ASE and PEF significantly increased the protein extract efficiency of the fish by-products (p < 0.05) by up to 80%. SDS-PAGE results showed that ASE and PEF treatments changed the molecular size distribution of the protein in the extracts, which was specifically expressed as the change in the area or number of bands between 5 and 250 kDa. The antioxidant capacity of the extracts was evaluated by oxygen radical absorbance capacity (ORAC) and total antioxidant capacity (ABTS) assays. The results showed that both ASE and PEF treatments significantly increased the antioxidant capacity of rainbow trout and sole skin and head extracts (p < 0.05). ASE and PEF extraction processes can be used as new technologies to extract high-added-value compounds from fish by-products.

Neutral Lipids, Glycolipids, and Phospholipids, Isolated from Sandfish (Arctoscopus japonicus) Eggs, Exhibit Anti-Inflammatory Activity in LPS-Stimulated RAW264.7 Cells through NF-κB and MAPKs Pathways

Total lipids were extracted from sandfish (Arctoscopus japonicus), and then they were separated into the following three lipid fractions: neutral lipids, glycolipids, and phospholipids. In this study, we analyzed the lipid fractions of A. japonicus eggs and we determined their anti-inflammatory activity in RAW264.7 macrophage cells. In these three lipid-fractions, the main fatty acids were as follows: palmitic acid (16:0), oleic acid (18:1n-9), docosahexaenoic acid (DHA, 22:6n-3), and eicosapentaenoic acid (EPA, 20:5n-3). Among the lipid fractions, phospholipids showed the highest concentration of DHA and EPA (21.70 ± 1.92 and 18.96 ± 1.27, respectively). The three lipid fractions of A. japonicus significantly suppressed the production of NO in macrophages. Moreover, they also significantly inhibited the expression of iNOS, COX-2, IL-6, IL-1β, and TNF-α, in a dose-dependent manner. Furthermore, the lipid fractions of A. japonicus suppressed the nuclear translocation of NF-κB p65 subunits in a dose-dependent manner. In addition, they attenuated the activation of MAPKs (p38, ERK1/2, and JNK) phosphorylation in LPS-stimulated RAW264.7 cells. These results indicate that all the lipid fractions of A. japonicus exert anti-inflammatory activity by suppressing the activation of NF-κB and MAPK pathways. Therefore, the lipid fractions of A. japonicus might be potentially used as anti-inflammatory agents.

Comparison of Chemical Composition and Safety Issues in Fish Roe Products: Application of Chemometrics to Chemical Data

Processed fish roes are acquiring considerable importance in the modern food market, entering more and more often as an ingredient in food preparation and as caviar substitutes. In this study, we defined quality, traceability and safety issues related to processed fish roe products from different species. The results obtained allowed to distinguish eggs originated from different fish species and to discriminate between fish roes and caviar samples obtained from four different sturgeons species. We observed that roes showed a trend of grouping according to ecological and reproductive habits of fish species. We highlighted the differences between eggs originated by farmed and freshwater fish, enriched in n6 polyunsaturated fatty acids (PUFAs), and all the others, in which n3 PUFAs were prevalent. In addition, we evaluated processed fish roes under a food safety point of view, combining microbiological analysis with the determination of organic acids, used in some products as authorized preservatives. Microbiological characterization has proved a general good hygienic level for these products. Organic acids determination showed values in compliance with European Union (EU) regulations in almost of samples; in some cases, we found a mismatch between the organic acids detected and what was reported in labels. Processed fish roes could be considered a safe product that can provide to human nutrition a valuable content of essential fatty acids.

Chemical composition and functional properties of roe concentrates from skipjack tuna (Katsuwonus pelamis) by cook-dried process

The objective of this study was to investigate physicochemical properties of protein concentrate from skipjack tuna roe by a cook-dried (boiled or steamed-dried) process, and to evaluate their food functional properties. The yields of boil-dried concentrate (BDC) and steam-dried concentrate (SDC) prepared from skipjack tuna roe were 22.4 for BDC and 24.4% for SDC. Their protein yields were 16.8 and 18.4%, respectively. In terms of major minerals of the BDC and SDC, sulfur (853.2 and 816.6 mg/100 g) exhibited the highest levels followed by potassium, sodium and phosphorus. The prominent amino acids of roe protein concentrates (RPCs) were Glu, Asp, Leu and Val. The BDC and SDC showed a higher buffer capacity than egg white (EW) at the pH-shift range. The pH-shift treatment significantly improved the water holding capacities of RPCs, except pH 6. But they had a low solubility across the pH-shift range. The foaming capacities (104%-119%) of BDC and SDC were significantly lower than those of EW (p < .05), and their foam stabilities were not observed. Emulsifying activity index (m2/g protein) of RPCs and EW was 2.3 for BDC, 11.1 for SDC and 18.0 for EW. RPCs in the food and seafood processing industries will be available as egg white alternative protein sources and will be available as ingredients of surimi-based products in particular.

Characterisation of hydrolysates prepared from engraved catfish (Nemapteryx caelata) roe by serial hydrolysis

Protein hydrolysates were prepared from defatted engraved catfish roe using alcalase enzyme by a two-stage serial hydrolysis process. The soluble hydrolysate formed after first stage of hydrolysis was removed (RH-1) and fresh enzyme was added at the same concentration to achieve further hydrolysis (RH-2). Further, compositional, surface-active and antioxidant properties of both hydrolysates were compared. The SDS-PAGE profile showed two distinct bands for RH-1, whereas no bands were visible for RH-2. On the other hand, gel filtration chromatography of the hydrolysates indicated 3-4 distinct fractions. Both the hydrolysates showed similar foam forming abilities, however, RH-1 exhibited poor foam stability. Emulsion properties of RH-1 were superior to that of RH-2. The major fractions eluted through gel filtration column were screened for antioxidant properties. Higher DPPH radical scavenging and metal chelating properties were observed for RH-1 second fragment, whereas FRAP and Fe(2+) reducing power was highest for second fragment of RH-2.