Effects of okra (Abelmoschus esculentus L.) leaves, fruits and seeds extracts on European sea bass (Dicentrarchus labrax) leukocytes, and their cytotoxic, bactericidal and antioxidant properties.

Okra, Abelmoschus esculentus L., is a popular vegetable crop with many bioactive compounds. The in vitro immunostimulant, cytotoxic, bactericidal and antioxidant activities of ethanolic extracts obtained from different parts of okra (leaves, fruits, and seeds) were studied. Phytochemical screening of hydroalcoholic extracts of okra leaves, fruits and seeds revealed a significant content of total phenols and flavonoids. Notable effects on the activities of leukocytes in the head kidney of European sea bass (Dicentrarchus labrax) (viability, phagocytic ability and capacity, and respiratory burst), as well as on peroxidase leukocyte contents were detected after incubation for 24 h with different concentrations (0.01-1 mg mL-1) of the extracts. The mean concentrations (0.1 and 0.5 mg mL-1) of the different extracts increased the phagocytic ability and respiratory activity of head kidney leukocytes. However, the mean concentrations (0.1 mg mL-1) of leaf and fruit extracts significantly decreased the peroxidase activity of leukocytes. In addition, all ethanolic okra extracts at higher concentrations (1 mg mL-1) produced a marked reduction in the viability of the DLB-1 cell line compared to the viability recorded in the control samples. In addition, ethanolic extracts used at 0.5 and 1 mg mL-1 had a significant cytotoxic effect on the viability of PLHC-1 cells. Finally, all doses of seed and leaf extracts at higher concentrations (0.5 and 1 mg mL-1) showed significant bactericidal activity on two fish pathogenic bacteria, Vibrio anguillarum and V. harveyi strains. Finally, a remarkable antioxidant activity was detected on the ethanolic extracts. All these results point to their possible use as an alternative to chemical compounds in farmed fish.

Skin mucus metabolomics provides insights into the interplay between diet and wound in gilthead seabream (Sparus aurata).

The molecular processes underlying skin wound healing in several fish species have been elucidated in the last years, however, metabolomic insights are scarce. Here we report the skin mucus metabolome of wounded and non-wounded gilthead seabream (Sparus aurata) fed with silk fibroin microparticles, a functional additive considered to accelerate the wound healing process. The three experimental diets (commercial diet enriched with 0 mg (control), 50 mg or 100 mg of silk fibroin microparticles Kg-1) were administered for 30 days and thereafter, a skin wound was inflicted. Skin mucus was collected on day 30 of feeding and 7 days post-wounding and subjected to metabolomic analysis by Ultra Performance Liquid Chromatography coupled with a high-resolution quadrupole-orbitrap mass spectrometry. The most enriched metabolite class was amino acids and derivatives, followed by nucleotides, nucleosides and analogues and carbohydrates and their derivatives. Metabolomic profiles revealed that the diet had a more profound effect than wounding in skin mucus. Metabolic pathway analysis of significantly affected metabolites revealed perturbations in the aminoacyl t-RNA biosynthesis in the skin. In particular, skin wound resulted in a decreased methionine level in mucus. Further, silk fibroin supplementation increased methionine level in skin mucus, which correlated with several wound morphometric parameters that characterized the epithelial healing capacity in seabream. The results provided new insight into the physiological consequences of skin wounds and how these processes could be influenced by dietary manipulation.

Phytochemical compounds, antiradical capacity, and in vitro inhibitory effect against fish pathogenic bacteria of okra fruits (Abelmoschus esculentus L.) at different maturity stages.

Background: Abelmoschus esculentus L., okra, has been known as a healthy plant and classically employed in food and folk medicine for several human and animal diseases. Aim: The in vitro antioxidant and antibacterial capacities, in addition to the phytochemical compounds of the okra fruit extracts gathered at three maturity stages, were the objectives of this study. Methods: This study examined the modifications in total phenolic content (TPC), total flavonoid content (TFC), and antioxidant and antibacterial capacities of three okra fruit hydroalcoholic extracts during three comestible maturity stages. The different maturity stages of okra pods were demonstrated as early-stage, mid-stage, and late-stage maturation. Results: The mid-stage of okra fruit maturity had the highest TPC (43.27 ± 2.029 mg GAE g-1), TFC (29.96 ± 0.19 mg RE g-1), and antioxidant capacity (75.64% ± 0.79%). Moreover, at mid-stage maturity, okra fruit extracts exhibited a major antibacterial effect against Vibrio anguillarum. The phenolic content was significantly increased at the mid-stage maturity, while the flavonoid level and the antioxidant activity were greatly decreased at the end of fruit maturity. Conclusion: The results confirmed that A. esculentus L. fruits at mid-stage maturity are an excellent source of biomolecules with high antiradical and bactericidal activities, which could be used as functional foods and as an option for chemical compounds for fish farming to prevent and treat numerous marine animal diseases.

Solid Lipid Nanoparticles Administering Antioxidant Grape Seed-Derived Polyphenol Compounds: A Potential Application in Aquaculture.

The supply of nutrients, such as antioxidant agents, to fish cells still represents a challenge in aquaculture. In this context, we investigated solid lipid nanoparticles (SLN) composed of a combination of Gelucire® 50/13 and Precirol® ATO5 to administer a grape seed extract (GSE) mixture containing several antioxidant compounds. The combination of the two lipids for the SLN formation resulted in colloids exhibiting mean particle sizes in the range 139-283 nm and zeta potential values in the range +25.6-43.4 mV. Raman spectra and X-ray diffraction evidenced structural differences between the free GSE and GSE-loaded SLN, leading to the conclusion that GSE alters the structure of the lipid nanocarriers. From a biological viewpoint, cell lines from gilthead seabream and European sea bass were exposed to different concentrations of GSE-SLN for 24 h. In general, at appropriate concentrations, GSE-SLN increased the viability of the fish cells. Furthermore, regarding the gene expression in those cells, the expression of antioxidant genes was upregulated, whereas the expression of hsp70 and other genes related to the cytoskeleton was downregulated. Hence, an SLN formulation containing Gelucire® 50/13/Precirol® ATO5 and GSE may represent a compelling platform for improving the viability and antioxidant properties of fish cells.

A Bioactive Extract Rich in Triterpenic Acid and Polyphenols from Olea europaea Promotes Systemic Immunity and Protects Atlantic Salmon Smolts Against Furunculosis.

In the present study, the modulation of the transcriptional immune response (microarray analysis) in the head kidney (HK) of the anadromous fish Atlantic salmon (Salmo salar) fed a diet supplemented with an olive fruit extract (AQUOLIVE®) was evaluated. At the end of the trial (133 days), in order to investigate the immunomodulatory properties of the phytogenic tested against a bacterial infection, an in vivo challenge with Aeromonas salmonicida was performed. A total number of 1,027 differentially expressed genes (DEGs) (805 up- and 222 downregulated) were found when comparing the transcriptomic profiling of the HK from fish fed the control and AQUOLIVE® diets. The HK transcripteractome revealed an expression profile that mainly favored biological processes related to immunity. Particularly, the signaling of i-kappa B kinase/NF-kappa and the activation of leukocytes, such as granulocytes and neutrophils degranulation, were suggested to be the primary actors of the innate immune response promoted by the tested functional feed additive in the HK. Moreover, the bacterial challenge with A. salmonicida that lasted 12 days showed that the cumulative survival was higher in fish fed the AQUOLIVE® diet (96.9 ± 6.4%) than the control group (60.7 ± 13.5%). These results indicate that the dietary supplementation of AQUOLIVE® at the level of 0.15% enhanced the systemic immune response and reduced the A. salmonicida cumulative mortality in Atlantic salmon smolts.

Dietary administration effects of exopolysaccharide from potential probiotic strains on immune and antioxidant status and nutritional value of European sea bass (Dicentrarchus labrax L.).

The use of biological immunostimulants is considered a valuable practice to improve culture conditions in aquaculture sector that may help to increase production and maintain healthy environment. We undertook this study in order to evaluate the potential effect of the administration of two exopolysaccharides (EPS) "EPLB" and "EPB" derived from potential probiotic strains on immune and antioxidant status of European sea bass (Dicentrarchus labrax L.) larvae. In order to find out if the EPSs have an effect on the biochemical composition during the trial period, the nutritional value has been evaluated. The results revealed that expression levels of immune-relevant genes (infg, Il1b, Il8, Il6 and tcr-ß) in the gut and head kidney and the scavenging enzymes (cat, sod, gr) genes in the liver were modulated. In fact, the dietary supplementation with the tested EPSs, significantly enhances the expression of immune-associated genes in the head-kidney, particularly infg and tcrß, as well as catalase gene in liver. During the period of study, EPSs administration did not affect the fatty acid profiles of larvae, which is balanced. This is confirmed by the Docosahexaenoic acid / Eicosapentaenoic acid ratio and demonstrates that EPLB and EPB can be administrated without any negative effect on biochemical composition of European sea bass. The present findings provided evidence that the tested EPSs with antibacterial and antioxidant activities can enhance immune response without negative effect on the biochemical composition. The used EPSs can be considered as a good source of natural functional aquafeed ingredients for European sea bass.

Effects of long-term ingestion of white tea on oxidation produced by aging and acute oxidative damage in rats.

The infusion tea extracted from the leaves of the plant Camellia sinensis can be used in the prevention of cancer, cardiovascular and neurodegenerative diseases, and aging, while adriamycin (ADR) is an anticancer drug that increases oxidative stress in cells. The present study evaluated the protective effect of the long-term consumption of white tea used at two different doses against the oxidative stress produced by aging and acute oxidation caused ADR treatment. At wearing, rats received distilled water (control), or 0.15 (dose 1) or 0.45 mg (dose 2) of solid tea extract/kilogram body weight in their drink. At 12 months, about half of the rats of each group were injected with a bolus of ADR, and six rats of the control group with an injection of saline solution and sacrificed. The rest of the animals continued in their cages until 24 months of age, when they were sacrificed. Lipid and protein oxidation of liver and brain microsomes was analyzed by measuring hydroperoxide and carbonyl levels. White tea consumption for 12 months at a non-pharmacological dose was seen to reverse the oxidative damage caused by ADR in both liver and brain, while the consumption of white tea for 20 months at a non-pharmacological dose had no effect on carbonyl or hydroperoxides in these tissues. The long-term ingestion of white tea protected tissues from acute oxidative stress but did not affect chronic oxidative agents such aging.