Corn Husk Phenolics Modulate Hepatic Antioxidant Response in Nile Tilapia (Oreochromis niloticus) Exposed to Hypoxia.

The hypoxia conditions in intensive farming systems generate oxidative stress related to oxidative damage and mortality of fish. Corn husk meal (CHM), as a source of antioxidants, might modulate the antioxidant response and prevent the damage elicited by hypoxia. This study evaluated CHM's ability to modulate a hepatic response in Nile tilapia exposed to hypoxia. A control and a test diet supplemented with 25 g CHM/kg feed were formulated. Ninety Nile tilapias (5.09 ± 0.55 g initial weight) were fed for 36 days to evaluate growth, feed efficiency, and hepatic antioxidant response (CAT, catalase; SOD, superoxide dismutase, and GPx, glutathione peroxidase) in normal oxygen conditions (normoxia). After the feeding trial (36 days), fish were exposed to hypoxia (1.5 ± 0.2 mg/L dissolved oxygen), and the hepatic antioxidant response was determined. There was no significant effect of CHM on growth and feed efficiency. The CAT activity was significantly increased in tilapias exposed to hypoxia and fed the test diet compared to the control group exposed to hypoxia. The SOD and GPx activities were unchanged in tilapias in normoxia and hypoxia conditions. Results suggest that CHM dietary supplementation promotes the antioxidant response in Nile tilapia exposed to hypoxia through CAT modulation.

Polyphenolic Extracts from Spent Coffee Grounds Prevent H2O2-Induced Oxidative Stress in Centropomus viridis Brain Cells.

Oxidative stress in aquatic organisms might suppress the immune system and propagate infectious diseases. This study aimed to investigate the protective effect of polyphenolic extracts from spent coffee grounds (SCG) against oxidative stress, induced by H2O2, in C. viridis brain cells, through an in vitro model. Hydrophilic extracts from SCG are rich in quinic, ferulic and caffeic acids and showed antioxidant capacity in DPPH, ORAC and FRAP assays. Furthermore, pretreatment of C. viridis brain cells with the polyphenolic extracts from SCG (230 and 460 µg/mL) for 24 h prior to 100 µM H2O2 exposure (1 h) significantly increased antioxidant enzymes activity (superoxide dismutase and catalase) and reduced lipid peroxidation (measured by MDA levels). These results suggest that polyphenols found in SCG extracts exert an antioxidative protective effect against oxidative stress in C. viridis brain cells by stimulating the activity of SOD and CAT.

Production of Protein Hydrolysates Using Marine Catfish Bagre panamensis Muscle or Casein as Substrates: Effect of Enzymatic Source and Degree of Hydrolysis on Antioxidant and Biochemical Properties.

Protein hydrolysates from fishery byproducts have resulted to be nutraceutical ingredients with potential to be applied in human nutrition; however, critical quality attributes are dependent on some process parameters such as enzyme source and degree of hydrolysis. This study analyzed the biochemical properties and in vitro antioxidant activity (using DPPH, ABTS, and FRAP assays), of protein hydrolysates at 10, 20, and 30% degree of hydrolysis (DH), measured by pH-STAT and prepared from sea catfish (Bagre panamensis) muscle and casein as protein sources by treatment with alcalase (ALC) and a semi-purified protease extract (SPE) from B. panamensis intestinal tissues as enzyme sources. With SPE, the DH was reached faster than ALC regardless of the protein substrate used. Sea catfish muscle (MUSC) hydrolysate made with SPE at 30% DH showed the highest antioxidant activity (DPPH: 118.8 µmoles TE/mg; ABTS: EC50 of 1.5 mg/mL). In FRAP assay, the MUSC hydrolysates produced with SPE or ALC at 20% DH showed the higher activity (0.38 and 0.40 µmoles TE/mg, respectively). MUSC hydrolysates made with SPE contained the highest proportion of peptides with MW < 1.35 kDa and had a high protein content (72 to 78%), and almost 50% of the amino acids were essential. These results suggest that intestinal proteases and muscle of marine catfish represent a potential source to elaborate antioxidant protein hydrolysates. Our results promote the full utilization of this fish species and offer a biotechnological strategy for the management and valorization of its byproducts.

Exploitation of Agro-Industrial Waste as Potential Source of Bioactive Compounds for Aquaculture.

The agroindustry generates a large amount of waste. In postharvest, food losses can reach up to 50%. This waste represents a source of contamination of soil, air, and bodies of water. This represents a problem for the environment as well as for public health. However, this waste is an important source of bioactive compounds, such as phenolic compounds, terpenes, and ß-glucans, among others. Several biological activities have been attributed to these compounds; for example, antioxidant, antimicrobial, gut microbiota, and immune system modulators. These properties have been associated with improvements in health. Recently, the approach of using these bioactive compounds as food additives for aquaculture have been addressed, where it is sought that organisms, in addition to growing, preserve their health and become disease resistant. The exploitation of agro-industrial waste as a source of bioactive compounds for aquaculture has a triple objective-to provide added value to production chains, reduce pollution, and improve the well-being of organisms through nutrition. However, to make use of the waste, it is necessary to revalue them, mainly by determining their biological effects in aquaculture organisms. The composition of bioactive compounds of agro-industrial wastes, their biological properties, and their application in aquaculture will be addressed here.

Overfeeding a High-Fat Diet Promotes Sex-Specific Alterations on the Gut Microbiota of the Zebrafish (Danio rerio).

Diet modulates the gut microbiota and is one of the main factors promoting obesity and overweight. In the present study, we investigated the effect of a high-fat diet (HFD) on the gut microbiota of the zebrafish (Danio rerio). Fish were separated into three groups and fed in different regimes: low fat, high fat, and high fat overfed; the experiments were performed on males and females separately. We analyzed more than 2.6 million sequences of variable region V3 of the 16S rRNA gene generated by the Illumina Miniseq platform, clustered to 97% similarity with vsearch and classified with the EzBioCloud database. The weight gain, condition factor (K), and body mass index were calculated as indicators of obesity. Multivariate analysis (PERMANOVA and ANOSIM) and diversity indices (Shannon and Dominance) revealed that overfeeding a HFD disturbs the gut microbiota differently in males and females suggesting that sex is a significant factor (p < 0.05) for the composition of the gut microbiota of zebrafish. The results also indicate that a HFD provided in a basal caloric regime does not promote obesity or alterations in the gut microbiota.

Propiedades antioxidantes e inmunoestimulantes de polifenoles en peces carnívoros de cultivo / Antioxidant and immunostimulant properties of polyphenols in carnivorous farmed fish

Resumen El cultivo intensivo de peces es una estrategia econòmicamente importante para producir alimento. Sin embargo, las prácticas de cultivo intensivo generan estrés oxidativo e inmunosupresión, lo que ocasiona pérdidas de la calidad del especimen y aumento en la mortalidad. Para contrarrestar estos efectos, se ha optado por la administración de vegetales como fuente de polifenoles con propiedades antioxidantes e inmunoestimulantes en peces carnívoros de cultivo. El objetivo de este trabajo fue describir los efectos de los polifenoles de origen vegetal como antioxidantes e inmunoestimulantes en peces carnívoros, y promover su uso como ingredientes funcionales en la acuicultura. Los vegetales como fuente de polifenoles tienen la capacidad de mejorar los sistemas de defensa inmune y antioxidante de las especies analizadas, con un tejido de mejor calidad nutricional y un mayor contenido endógeno de antioxidantes. No obstante, las propiedades biológicas de los polifenoles dependen del tipo y concentra ción en el vegetal, de la dosis y el tiempo de administración, así como de la matriz alimentaria, la cual determina la bioaccesibilidad y biodisponibilidad de los polifenoles en el organismo. Es la información generada sobre el efecto de los polifenoles en la calidad post mortem, por lo que se deben realizar más estudios.

Abstract Fish production by intensive aquaculture, is an economically important strategy to produce food. However, intensive fish farming generates oxidative stress and suppress the immune system, causing loss of product quality and increasing fish mortality rates. To diminish these effects, plants as a source of polyphenols with antioxidants and immunostimulant properties were administered to carnivorous farmed fish. The aim of this study was to describe the effects of plant polyphenols as antioxidants and immunostimulants on carnivorous fish, and to promote their use as functional ingredients in aquaculture. Plants as a source of polyphenols showed the ability to improve the immune and antioxidant defense systems of the analyzed species, resulting in a tissue of better nutritional quality and a higher endogenous antioxidant content. However, the biological properties of polyphenols are dependent on the type of plant and their concentration within it, the dose and the time of administration, as well as the food matrix, which determines their bioaccessibility and bioavailability in the organism. There is little information on the effec of polyphenols in post mortem quality; therefore, further studies should be conducted.